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Sample records for molecular absorption spectrophotometry

  1. Measurement of uranium concentration by molecular absorption spectrophotometry by means optical fibers; Medicion continua de concentracion de uranio por espectrofotometria de absorcion molecular mediante fibras opticas

    Energy Technology Data Exchange (ETDEWEB)

    Gauna, Alberto C.; Pascale, Ariel A. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Centro Atomico Ezeiza. Agencia Minipost

    1996-07-01

    An on-line method for measuring the concentration of uranium in uranyl nitrate-nitric acid aqueous solutions is described. The method is based on molecular absorption spectrophotometry with transmission of light by means of optical fibers. It is ideally suited for control and processes development applications. (author)

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

    Science.gov (United States)

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

    2002-07-15

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

  3. Spectrophotometry of six broad absorption line QSOs

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. [Study on cadmium absorption in pumpkin by atomic absorption spectrophotometry].

    Science.gov (United States)

    Li, Zhen-Xia; Jing, Rui-Jun; Dong, Wei-Hua; Li, Xin-Zheng; Liu, Hong

    2006-08-01

    A study was carried out on the characteristic of cadmium absorption in pumpkin by atomic absorption spectrophotometer. The results show that the cadmium absorption amount in pumpkin increased with the increase in cadmium concentration. Meanwhile the cadmium absorption amount in pumpkin increased with time. Eight hours after being cultured in the liquid, the cadmium absorption amount became saturated. The cadmium absorption rate reached the peak after 2 hours, then the absorption rate gradually reduced. The cadmium absorption amount in pumpkin is less in acid or alkali compared with neutral condition. And the absorption amount became minimum in pH 3, while maximum in pH 7.

  6. Determination of Lead in Blood by Atomic Absorption Spectrophotometry1

    Science.gov (United States)

    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

  7. Determination of Lead in Urine by Atomic Absorption Spectrophotometry1

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  9. 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.

    Science.gov (United States)

    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 × 10(4), 1.162 × 10(5) 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  μ g/ml, resp.); linearity (5-70, 5-30, and 10-150  μ g/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  μ g/ml, resp.); linearity (5-70 and 10-150  μ g/ml, resp.); and correlation coefficients (0.9989 and 0.9997, resp.).

  10. Comparison of liposome entrapment parameters by optical and atomic absorption spectrophotometry.

    Science.gov (United States)

    Yoss, N L; Popescu, O; Pop, V I; Porutiu, D; Kummerow, F A; Benga, G

    1985-01-01

    Methods for the complete characterization of liposomes prepared by ether-injection are described in detail. The validity of atomic absorption spectrophotometry for measuring markers of trapped volume was checked by comparative determinations of markers with established optical spectrophotometrical methods. The favorable results using atomic absorption spectrophotometry to quantitate the marker Mn2+ are of particular relevance as manganese ion is also the paramagnetic probe in n.m.r. measurements of water permeability of liposomes; our results indicate that in such measurements no other marker need be incorporated.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2005-05-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  18. [Speciation analysis of trace elements Cu, Fe and Zn in serum by flame atomic absorption spectrophotometry].

    Science.gov (United States)

    Hu, Jun; Chang, Yao-Ming; Gao, Shuang-Bin; Hai, Chun-Xu; Li, Jin-Sheng; Xie, Xiao-Ping

    2008-03-01

    Since biological functions of the elements are generally different, depending on their chemical forms, chemical speciation analysis is really important in metallomics research. Thus, multielement analysis and chemical speciation of the elements in serum were carried out in the present work. A hyphenated technique was developed for high-throughput speciation analysis of the copper, iron and zinc in serum by molecular biology technology and flame atomic absorption spectrophotometry (AAS). Here, Cu, Fe and Zn in serum were classifyied as the forms of combination and non-combination. The serum protein was precipitated by 60% concentration of ethanol under hypothermy. The forms of combination of Cu, Fe and Zn in serum which combined with proteins were in precipitations, and the forms of non-combination of Cu, Fe and Zn in serum, which were free ions, were in supernatant. The total amount of Cu, Fe and Zn in serum and the amount of the forms of non-combination of Cu, Fe and Zn were analyzed by AAS. The amount of the forms of combination of Cu, Fe and Zn was obtained by calculation. The detection limit of Cu in serum by the method is around and 9.84 x 10(-3) microg x mL(-1). For Fe and Zn, the detection limit is about 2.76 x 10(-2) microg x mL(-1) and 1.06 x 10(-3) microg x mL(-1), respectively. The percentage recovery of trace elements Cu, Fe and Zn by the proposed procedure is in the range 95.0%-101.0%, 95.0%-102.0% and 95.0%-103.0%, respectively. The relative standard deviation (RSD) of trace elements Cu, Fe and Zn in the serum is in the range 1.88%-2.26%, 0.56%-1.59% and 0.34%-1.36%, respectively. Speciation of trace elements Cu, Fe and Zn in the serum of SD rat were analyzed by the method.

  19. Neutron activation analysis and atomic absorption spectrophotometry for the analysis of fresh, pasteurised and powder milk

    Energy Technology Data Exchange (ETDEWEB)

    Wasim, M.; Rehman, S.; Arif, M.; Fatima, I.; Zaidi, J.H. [Pakistan Inst. of Nuclear Science and Technology, Islamabad (Pakistan). Chemistry Div.

    2012-07-01

    This study shows the application of semi-absolute k{sub 0} instrumental neutron activation analysis (k{sub 0}-INAA), epithermal neutron activation analysis (ENAA) and atomic absorption spectrophotometry (AAS) for the determination of 21 elements (Br, Ca, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sc Sr, and Zn) in different types of milk samples. The ENAA was required for the determination of iodine, AAS for Cu, Ni and Pb and the rest of the elements were measured by k{sub 0}-INAA. Thirteen elements (Br, Ca, Cl, Cs, Cu, Fe, K, Mg, Na, P, Rb, Sr and Zn) were identified in all milk samples. Ni was detected in eleven and Pb in two samples. Concentrations of most of the elements were within the ranges of the world reported data. The data was further explored by principal component analysis to find relationships between samples and elements. (orig.)

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

    Science.gov (United States)

    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.

  1. [Determination of trace elements in Aloe barbadensis Miller irrigated with seawater by atomic absorption spectrophotometry].

    Science.gov (United States)

    Liu, Chun-Hui; Wang, Chang-Hai; Liu, Zhao-Pu

    2008-03-01

    The dry leaves of Aloe barbadensis Miller irrigated with seawater were dissolved in nitric acid and then oxygenated by perchloric acid. Nine kinds of trace elements in the samples were determined by atomic absorption spectrophotometry, including calcium, potassium, magnesium, sodium, manganese, zinc, iron, copper and lead, with added lanthanum chloride as releaser to eliminate the interference of co-existent ions. The recoveries were 96.58%-104.31%, and the relative standard deviations of sample determination (10 times) were less than 2%. This method is simple, sensitive and rapid with satisfactory results and good reproducibility. The results indicated that there were rich Ca, Mg, K and Na, and moderate Mn, Zn and Fe elements in the Aloe barbadensis Miller irrigated with seawater. However, the concentrations of Cu and Pb were low. Therefore, Aloe barbadensis Miller irrigated with seawater has officinal and economic values. These results provide data for further research on Aloe barbadensis Miller irrigated with seawater.

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

    Science.gov (United States)

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

    1984-11-01

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

  3. [Atomic absorption spectrophotometry study of copper ion release by copper-bearing intrauterine devices].

    Science.gov (United States)

    Berthou, J; Chrétien, F C; Driguez, P A

    1998-11-01

    Copper release from copper-bearing IUD's was studied in vitro and in vivo using atomic absorption spectrophotometry in deionized water, normal saline solution and normal ovulatory cervical mucus. In these media, copper release from a 375 mm2 DIU occurs without latency, showing comparable amounts for identical time intervals. Daily copper release was shown to be respectively 8 and 11 times higher in cervical mucus and normal saline solution than in deionized water. Although copper ions are detectable in ovulatory cervical mucus under physiological conditions, the copper content appears 5 to 6 times higher in women bearing a copper IUD. Obviously, the copper amount is dependent on the copper exposed surface: the daily in vitro release from a 250 mm2 IUD is 18% inferior to that observed from a 375 mm2 model. In vivo, the daily copper release in ovulatory mucus of 380 or 200 mm2 IUD users is respectively 5 and 3.5 times higher than in controls.

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

    Science.gov (United States)

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

    2007-07-01

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

  5. Comparative study of heavy metals in dried and fluid milk in Peshawar by atomic absorption spectrophotometry.

    Science.gov (United States)

    Lutfullah, Ghosia; Khan, Abid Ali; Amjad, Azra Yasmeen; Perveen, Sajida

    2014-01-01

    Various essential and toxic heavy metals (Ca, Mg, Cu, Zn, Fe, Mn, Pb, Cd, Cr, and Ni) contents in various types of dried (infant formula and powdered) and fluid (fresh and processed) cow milk were assessed by atomic absorption spectrophotometry. The milk samples were collected from local markets of different parts of Peshawar city, Pakistan. Heavy metal concentrations varied significantly depending upon the type of milk. The heavy metal concentrations in most of the samples were within normal and permissible ranges. It was observed that the samples contained considerable amounts of calcium, while magnesium levels were well above the required levels. The results also revealed that copper levels were slightly lower than the permissible limits. The concentration of zinc in dried milk samples was greater than the values for the liquid milk types. Infant milk formulae had higher iron levels as compared to other milk samples because of the added constituents. Significant differences were observed in the mean values of manganese and cadmium in different types of milk. The toxic metals were within the acceptable limits and did not show significant levels leading to toxicity.

  6. [The determination of chromium in feeds by flame atomic absorption spectrophotometry].

    Science.gov (United States)

    Wang, Jian; Jia, Bin; Guo, Li-ping; Lin, Qiu-ping

    2005-07-01

    Chromium in feeds is regulated by China Standard GB 13078-2001. A method of flame atomic absorption spectrophotometry for the determination of Cr in feeds has been developed in allusion to shortage of China standard method. Several acetylene flow-rate, burner-high and the additive of interference suppressor NH4Cl were studied respectively on the effect of sensitivities of Cr(III) and Cr(VI). The two sets analytical average results of Cr in feed sample determined by calibration curves of Cr(III) and Cr(VI) were tested by t test, no marked discrepancy was found. Optimum instrumental conditions of Cr(III) and Cr(VI) with same sensitivity were confirmed. Sensitivity was 0.014 microg x mL(-1) with detection limit 0.70 mg x kg(-1). The recoveries were 94.4%-104.9%. Relative standard deviation of sample determination (5-6 times) was 1.90%-4.08%. This method is simply, fast and exact, the detection limit was answered for Cr limit in feeds regulated by GB 13078-2001, it can be applied to the analysis of Cr in feeds.

  7. Assessment of provitamin A determination by open column chromatography/visible absorption spectrophotometry.

    Science.gov (United States)

    Rodriguez-Amaya, D B; Kimura, M; Godoy, H T; Arima, H K

    1988-12-01

    Determination of provitamin A content by open column chromatography/visible absorption spectrophotometry is assessed using food samples of varying carotenoid composition. A general method consisting of extraction with acetone, transfer to petroleum ether, saponification (optional), concentration, separation on activated MgO:Hyflo Supercel column developed with 1 to 15% acetone in petroleum ether, and quantitation of individual provitamins spectrophotometrically demonstrates repeatability comparable with that of high-performance liquid chromatographic (HPLC) methods. Overnight saponification (10% methanolic KOH, ambient temperature) does not degrade the provitamins and is unnecessary for kale, tomato, and squash; however, it is required for good separation of papaya carotenoids due to the presence of carotenol esters. The current Association of Official Analytical Chemists (AOAC) method is found to be inappropriate because (1) the volume of extracting solvent is not adjusted to the type of sample; (2) the less active alpha- and gamma-carotene, alpha- and beta-cryptoxanthin, and 5,6-monoepoxy-beta-cryptoxanthin (50% active) are quantified as beta-carotene (100% active); (3) inactive carotenoids such as xi-carotene and zeinoxanthin are also quantified as beta-carotene.

  8. Determination of calcium and magnesium in hydroethanolic extracts of propolis by atomic absorption flame spectrophotometry

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    E. Q. SANTANA

    2009-01-01

    Full Text Available

    Propolis is a natural product collected by honeybees and has a large range of pharmacological activity, including antimicrobial, antitumoral, antioxidant and anti-inflammatory. Its use as a popular medicine is increasing all over the world, creating a need for quality control of the commercial products. In this study the levels of calcium and magnesium in commercial hydroalcoholic propolis extracts from varios states of Brazil were determined by atomic absorption flame spectrophotometry and different values were obtained for northern and southern states. This study can be extended to the analysis of metals that are harmful to health. The results showed that the calibration curves were linear over a wide concentration range (0.5-4.0 µg.mL-1 for calcium and 0.05-0.4 µg.mL-1 for magnesium with good correlation coefficients (0.999 and 0.988, respectively. Good analytical recovery (94% was obtained. The proposed method showed adequate precision and relative standard deviation lower than 2 %. The method is accurate and precise as well as having advantages such as simplicity and speed. Keywords: hydroalcoholic propolis extract; mineralization; analysis; calcium; magnesium.

  9. Comparative Study of Heavy Metals in Dried and Fluid Milk in Peshawar by Atomic Absorption Spectrophotometry

    Science.gov (United States)

    Lutfullah, Ghosia; Khan, Abid Ali; Amjad, Azra Yasmeen; Perveen, Sajida

    2014-01-01

    Various essential and toxic heavy metals (Ca, Mg, Cu, Zn, Fe, Mn, Pb, Cd, Cr, and Ni) contents in various types of dried (infant formula and powdered) and fluid (fresh and processed) cow milk were assessed by atomic absorption spectrophotometry. The milk samples were collected from local markets of different parts of Peshawar city, Pakistan. Heavy metal concentrations varied significantly depending upon the type of milk. The heavy metal concentrations in most of the samples were within normal and permissible ranges. It was observed that the samples contained considerable amounts of calcium, while magnesium levels were well above the required levels. The results also revealed that copper levels were slightly lower than the permissible limits. The concentration of zinc in dried milk samples was greater than the values for the liquid milk types. Infant milk formulae had higher iron levels as compared to other milk samples because of the added constituents. Significant differences were observed in the mean values of manganese and cadmium in different types of milk. The toxic metals were within the acceptable limits and did not show significant levels leading to toxicity. PMID:24967439

  10. [Determination of thirteen metal elements in the plant Foeniculum vulgare Mill. by flame atomic absorption spectrophotometry].

    Science.gov (United States)

    Xue, Guo-qing; Liu, Qing; Han, Yu-qi; Wei, Hui-guang; Dong, Ting

    2006-10-01

    The objective of the paper is to determine the amount of metal elements of Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Co, Ni, Cd, Cr and Pb in the planted Foeniculum vulgare Mill. by flame atomic absorption spectrophotometry (FAAS), after the cinefaction and the digestion with HNO3-HClO4 (phi 4:1) at 90-95 degrees C and normal pressure. The optimum parameters of FAAS and the effects of solution medium on the results were investigated. The analytical results show that the amount of Na, K, Mg, Ca, Mn, Fe, Cu, Zn and Pb was 1508.7, 27653.0, 2036.0, 4848.1, 24.8, 323.5, 15.2, 23.7 and 10.8 microg x g(-1), respectively, and that of Co, Ni, Cd and Cr was not checked out in the samples. The recovery of standard addition is 97.45%-102.50%, the relative standard deviation (n=9) was 0.34%-2.77%. The characteristic method is quick, simple and convenient and the results are satisfactory.

  11. Determination of platinum, palladium, and lead in biological samples by atomic absorption spectrophotometry.

    Science.gov (United States)

    Tillery, J B; Johnson, D E

    1975-01-01

    A flameless atomic absorption method for the coextraction of platinum and palladium from biological and environmental samples by high molecular weight amine (HMWA) is given. Also, methods for lead determination in biological samples by use of extraction flameless analysis and direct aspiration-flame analysis are reported. A study of lead contamination of Vacutainer tubes is given. PMID:1227857

  12. [Determination of nine mineral elements in hulless barley by ultraviolet spectrophotometry and flame atomic absorption spectrometry].

    Science.gov (United States)

    Liu, Jin; Zhang, Huai-Gang

    2010-04-01

    The contents of nine mineral elements, including sulphur, zinc, calcium, magnesium, potassium, sodium, iron, copper and manganese in five hulless barley (Hordeum vulgare L. var. nudum Hook. f.) lines were determined by ultraviolet spectrophotometry and flames atomic absorption spectrometry (FAAS). For the determination of sulphur, the samples were dissolved by magnesia and anhydrous sodium carbonate at 250 degrees C for 0. 5 h and at 550 degrees C for 3 h in the muffle furnace, and then a certain amount of barium chloride was put into the sample solution for colorimetry of the UV-Vs spectrophotometer. For the determination of other eight mineral elements, all of the samples were dissolved by a kind of incinerating method: first, the sample was put into the muffle furnace at 250 degrees C for 0. 5 h and at 550 degrees C for 2.5 h, then two droplets of 50%HNO3 were distributed into each sample, and the last step was putting the sample into the muffle furnace at 550 degrees C for 0.5 h. And then all of the ash was dissolved by 50%HNO3 to 50 milliliter and determined by flames atomic absorption spectrometry. The precision, accuracy, repeatability and stability of the method were discussed too. The results showed that the relative standard deviations (RSD) were between 1.2% and 3.7%; The average recoveries were 97.44%-101.52% and the relative standard deviations (RSD) of sample determination were 1.3%-3.8%. The repeatability experiment showed that the relative standard deviations (RSD) were 2.6%-6.1%. And the content of each mineral element was the same after 24 hours; All these showed that the method has a good precision, accuracy, repeatability and stability. In all the hulless barley samples, the average contents were in the order of K > S > Mg > Ca > Fe > Na > Zn > Mn > Cu, and the contents of zinc, iron and manganese closely related to people's health were relatively higher than other crops. The data of the experiment could provide an accurate and credible evidence

  13. [Study on determination of eight metal elements in Hainan arecanut leaf by flame atomic absorption spectrophotometry].

    Science.gov (United States)

    Liu, Li-yun; Wang, Ping; Feng, Mei-li; Dong, Zhi-guo; Li, Jie

    2008-12-01

    Arecanut is a sort of palm that is important economic crop for the farmers in Hainan province of China, wherein there are many kinds of metal elements such as K, Ca, Na, Mg, Fe, Mn, Cu, Zn etc. These elements are important nutrition for the growth of arecanut. It is very valuable to study on the content of these metal elements in arecanut leaf in terms of plant nutriology of arecanut. The arecanut leaf in Wangling county, Hainan province of China was sampled by diagonal-field-sampling method. Refering to other plant sample determination by FAAS, the detailed studies are done with different digestion and determination methods. In the present paper the effects of mixed acid of HNO3-HClO4 digestion method on determining the amount of metal elements in the arecanut leaf by FAAS is reported, and another one is incineration digestion method. FAAS method was established for the determination of K, Ca, Mg, Na, Fe, Mn, Cu and Zn The samples were incinerated or heated with HNO3-HClO4 (4:1). In the meantime, the optimum parameters of FAAS and effects of different digestion methods on the results were discussed. The recovery rate of standard addition is 98.36%-102.38% in the first method; RSD is 0.42%-2.328% (n=6); The recovery rate of standard addition is 99.22%-103.72% in the second method; RSD is 0.58%-1.283 (n=6). The metal amount determined by the first method is lower than the second method, the ratio is 0.9703-0.9934. The two methods are satisfied, but the latter is better. It is precise enough to common experiment to use flame atomic absorption spectrophotometry with digestion by incineration If the especially precise experiment is required, the digestion methods with mixed acid of HNO3-HClO4 may be introduced. The paper introduced methods dependable for determination of some metal elements in order to study on some nutrient effects of these metal elements in arecanut.

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

    Science.gov (United States)

    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. Dosage du Zinc Sanguin et Plasmatique chez les Sujets Iraniens par Spectrophotometrie d'Absorption Atomique

    Directory of Open Access Journals (Sweden)

    Gh. MOHTAT

    1972-07-01

    Full Text Available The value of zinc in whole blood and plasma was determined in ? 16 Iranian subjects (121 women, and 95 men by atomic absorption spectrophotometry. In women, the mean value in whole blood was 71 8•+ ?12 p.g ' -L 100ml and in plasma was 91 --'- 37 ugfl OOml. In men, the mean va lue in whole blood was 775 ..:t 26? I'giiOOml and in plasma was 100 + 30 J1g!"OOml

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

    Science.gov (United States)

    Ejaz, M; Qureshi, M A

    1987-03-01

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

  17. Application of atomic absorption spectrophotometry to the rapid analysis of some elements in uranium; Application de la spectrophotometrie d'absorption atomique a l'analyse rapide de quelques elements dans l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Buffereau, M.; Robichet, J. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    After a brief review of the main conditions to analyse traces impurities in uranium, characteristics of the sample solution and analytical conditions in presence of uranium are studied. Some interferences are shown and comparative results are given. Limits of application of the method are discussed. (authors) [French] Apres avoir rapidement passe en revue les principales conditions d'application de la spectrophotometrie d'absorption atomique au dosage d'impurete dans l'uranium, on etudie les caracteristiques de la solution d'analyse et les conditions du dosage en presence d'uranium. On indique quelques interferences. Apres avoir mentionne quelques resultats comparatifs, on discute les limites d'application de la methode. (auteurs)

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

    Science.gov (United States)

    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…

  19. Analysis of Mercurial Preservatives in Bacterins, Vaccines, and Antisera by Atomic Absorption Spectrophotometry

    Science.gov (United States)

    Woodward, Paul W.; Pemberton, John R.

    1974-01-01

    A flameless atomic absorption method was developed for the determination of mercurial preservatives in biologicals. The assay was based on a quantitative determination of the mercury content of these preservatives. This method was used to analyze a variety of samples and yielded reproducible results with satisfactory recoveries. The procedure is presented in a simplified block diagram and described in detail relating its suitability for routine assay of large numbers of samples. PMID:4833363

  20. Interlaboratory bias in the determination of mercury concentrations in commercially available fish utilizing thermal decomposition/amalgamation atomic absorption spectrophotometry.

    Science.gov (United States)

    Butala, Steven J M; Scanlan, Larry P; Chaudhuri, Sanwat N; Perry, Deborah D; Taylor, Robert J

    2007-10-01

    Four commercially available fish fillets were freeze-dried, homogenized, and analyzed for mercury by the Texas A&M Trace Element Research Laboratory and the Utah Public Health Laboratory (UPHL) utilizing thermal decomposition/amalgamation atomic absorption spectrophotometry. Two-way analysis of variance detected bias in the data between the two laboratories. Some of the bias could be attributed to different calibration curve quantitation and near detection limit quantitation, albeit causal explanations could be confounded with other effects. Knowledge of analytical bias will aid interpretation of interlaboratory data. The swordfish mercury content, as determined by both laboratories, was about 1 ppm, while mercury content found in the Atlantic salmon was about 0.021 ppm. For the Alaskan halibut, the Texas A&M measured a mercury concentration of 0.155 ppm, while the UPHL measured a mercury concentration of 0.181 ppm for the same fish. The Texas A&M determined that the Canadian-raised salmon contained about 0.019 ppm of mercury, while the UPHL determined a mercury content of about 0.025 ppm for the same fish. The mercury found within the fish fillets did not exceed nationwide mercury mean values determined by the U.S. Food and Drug Administration.

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Science.gov (United States)

    Li, L; Zhang, J; Gao, C

    2001-08-01

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

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

    Science.gov (United States)

    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.

  4. Determination of Mecruy at Trace Level in Natural Water Samples by Hydride Generation Atomic Absorption Spectrophotometry after Cloud Point Extraction Preconcentration

    Institute of Scientific and Technical Information of China (English)

    Ji Ying SONG; Ming HOU; Li Xiang ZHANG

    2006-01-01

    A method for the determination of trace mercury in water samples by hydride generation atomic absorption spectrophotometry after cloud point extraction was proposed in the present work.The effects of pH, concentration of surfactant, and equilibration time on cloud point extraction were discussed. The enhancement factor of 20 and the detection limit of 0.039 μg/L were obtained for mercury with relative standard deviation of 4.8% (n = 11).

  5. 原子吸收法在酒类检测中的应用%Atomic Absorption Spectrophotometry in Wine Anlysis

    Institute of Scientific and Technical Information of China (English)

    马丽辉

    2014-01-01

    There are many kinds of metal elements in foods, atomic absorption spectrophotometry has the characteristics of simple, fast, accurate,highcostperformance,AAstechnologyiswidelyusedformetalsanalysisinwine.%食品中存在着多种金属元素,原子吸收法具有简捷、快速、准确、性价比高的特点,其检测技术在酒类检测中被广泛应用。

  6. A detailed study of thermal decomposition, amalgamation/ atomic absorption spectrophotometry methodology for the quantitative analysis of mercury in fish and hair.

    Science.gov (United States)

    Butala, Steven J M; Scanlan, Larry P; Chaudhuri, Sanwat N

    2006-11-01

    The analytical method for determining the concentration of mercury in fish by thermal decomposition, amalgamation/ atomic absorption spectrophotometry was thoroughly studied. Specific issues addressed were accurate modeling of instrumental response, the use of quartz and nickel boats, carryover effects, software limitations, and troubleshooting. The DMA-80 Direct Mercury Analyzer instrument was calibrated using a total of 22 points, and the resultant curves statistically analyzed. At minimum, second-order polynomials were required to adequately model the data. TORT-2 standard reference material was analyzed in both quartz and nickel boats and found to give equivalent performance in both types of vessels and well within the 95% confidence interval. DOLT-3 standard reference material also yielded values well within the 95% confidence interval, but the DORM-2 standard reference material did not. Carryover effects were found to be minimal with a new catalyst tube but increased with catalyst age. Blanks should be run after the analysis of high mercury content samples; however, when the catalyst has aged, two blanks are required to reduce apparent mercury signals to nominal blank values. Comparable results between thermal decomposition, amalgamation/atomic absorption spectrophotometry and cold-vapor atomic absorption spectrophotometry were demonstrated. The feasibility of using this instrument to analyze hair was also explored and found to be suitable. Software problems and limitations have been noted when attempting to implement a high-throughput methodology. Instrumental drift was found to be minimal when operated over long periods. Blank values can provide important diagnostic indicators.

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

    Science.gov (United States)

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

    1987-10-15

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

  8. Molecular absorption in transition region spectral lines

    CERN Document Server

    Schmit, Donald; Ayres, Thomas; Peter, Hardi; Curdt, Werner; Jaeggli, Sarah

    2014-01-01

    Aims: We present observations from the Interface Region Imaging Spectrograph (IRIS) of absorption features from a multitude of cool atomic and molecular lines within the profiles of Si IV transition region lines. Many of these spectral lines have not previously been detected in solar spectra. Methods: We examined spectra taken from deep exposures of plage on 12 October 2013. We observed unique absorption spectra over a magnetic element which is bright in transition region line emission and the ultraviolet continuum. We compared the absorption spectra with emission spectra that is likely related to fluorescence. Results: The absorption features require a population of sub-5000 K plasma to exist above the transition region. This peculiar stratification is an extreme deviation from the canonical structure of the chromosphere-corona boundary . The cool material is not associated with a filament or discernible coronal rain. This suggests that molecules may form in the upper solar atmosphere on small spatial scales...

  9. Increased plasma levels of lead in patients with amyotrophic lateral sclerosis compared with control subjects as determined by flameless atomic absorption spectrophotometry.

    Science.gov (United States)

    Conradi, S; Ronnevi, L O; Vesterberg, O

    1978-01-01

    The levels of lead in plasma were determined in 16 cases of amyotrophic lateral sclerosis (ALS) and 18 control subjects, using flameless atomic absorption spectrophotometry. The mean values were 0.52+/-0.22 microgram/100ml (ALS) and 0.37+/-0.13 microgram/100ml (controls), the difference is statistically significant (5% level). The values in both groups are lower than reported earlier for normal subjects. The findings are discussed against the background of the possible pathogenetic significance of retrograde axoplasmic flow in ALS. PMID:77896

  10. Determination of cations and metals in samples of beer and raw materials for beer production by ion chromatography (IC) and atomic absorption spectrophotometry (AAS) methods

    OpenAIRE

    Rajković, Miloš B.; Sredović-Ignjatović, Ivana; Ignjatović, Ljubiša; Nedović, Viktor; Prijić, Slobodan

    2015-01-01

    In order to control the quality of beer and raw materials for beer production, methods as ion chromatography (IC) and atomic absorption spectrophotometry (AAS) were applied. Water was analyzed as a raw material for beer production (urban, technological and demineralized water). Measurements of pH values indicated the increased pH values in the sample of tehnological water, but it had no impact on wort hopping, since the tested samples of wort, young beer and final product had a pH value in th...

  11. Quantum Entanglement Molecular Absorption Spectrum Simulator

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  13. Molecular hydrogen absorption systems in SDSS

    CERN Document Server

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

    2014-01-01

    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 Ly$\\alpha$ forest can effectively mimic H$_2$ 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 H$_2$ absorption systems can be confidently identified. We find that H$_2$ absorption systems with column densities $\\log {\\rm N_{H_2}} > 19$ can be detected in only less than 3% of SDSS quasar spectra. We estimate the upper limit on the detection rate of saturated H$_2$ absorption systems ($\\log {\\rm N_{H_2}} > 19$) in Damped Ly-$\\alpha$ (DLA) systems to be about 7%. We provide a sample of ...

  14. Aqueous complexation of citrate with neodymium(III) and americium(III): a study by potentiometry, absorption spectrophotometry, microcalorimetry, and XAFS.

    Science.gov (United States)

    Brown, M Alex; Kropf, A Jeremy; Paulenova, Alena; Gelis, Artem V

    2014-05-07

    The aqueous complexation of Nd(III) and Am(III) with anions of citrate was studied by potentiometry, absorption spectrophotometry, microcalorimetry, and X-ray absorption fine structure (XAFS). Using potentiometric titration data fitting the metal-ligand (L) complexes that were identified for Nd(III) were NdHL, NdL, NdHL2, and NdL2; a review of trivalent metal-citrate complexes is also included. Stability constants for these complexes were calculated from potentiometric and spectrophotometric titrations. Microcalorimetric results concluded that the entropy term of complex formation is much more dominant than the enthalpy. XAFS results showed a dependence in the Debye-Waller factor that indicated Nd(iii)-citrate complexation over the pH range of 1.56-6.12.

  15. 原子吸收法快速测定燃油中的铝%Rapid Determination of Aluminium in Fuel Oil by Atomic-absorption Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The determination of aluminium in fuel oil by means of the technique of direct dilution using a mixed-solvent system, inorganic aluminiun standard and atomic absorption spectrophotometry is researched. Good recoveries of aluminium added to fuel oil were demonstrated. Relative standard deviation of 3.6% was reached.%采用无机铝标准物和混合溶剂系统直接稀释-原子吸收法测定燃油中铝,回收率达92.4%,相对标准偏差为3.6%,特征质量浓度为0.85μg/mL.

  16. Assessment of the levels of some heavy metals in water in Alahsa Oasis farms, Saudi Arabia, with analysis by atomic absorption spectrophotometry

    Directory of Open Access Journals (Sweden)

    Fahad N. Assubaie

    2015-03-01

    Full Text Available For the first time, the levels of some heavy metals in water in Alahsa farms, Saudi Arabia were examined. Three types of water were analyzed including groundwater, mixed water and wastewater. The total contents of Mn, Fe, Cu, Zn, Cd and Pb were determined using graphite-furnace atomic absorption spectrophotometry. The results obtained were verified through the analysis of a certified reference material, the results of which are in good agreement with the certified consensus values. As recommended by the Food and Agriculture Organization, the level of heavy metals in groundwater and mixed water have been found to be suitable for irrigation purpose. However, the occurrence of some heavy metals that discharged directly from man-made activities without treatment could result in some environmental problems in the future. On the other hand, the spatial distribution of Mn and Fe has been found to increase from southeast to northwest.

  17. Molecular aspects of intestinal calcium absorption.

    Science.gov (United States)

    Diaz de Barboza, Gabriela; Guizzardi, Solange; Tolosa de Talamoni, Nori

    2015-06-21

    Intestinal Ca(2+) absorption is a crucial physiological process for maintaining bone mineralization and Ca(2+) homeostasis. It occurs through the transcellular and paracellular pathways. The first route comprises 3 steps: the entrance of Ca(2+) across the brush border membranes (BBM) of enterocytes through epithelial Ca(2+) channels TRPV6, TRPV5, and Cav1.3; Ca(2+) movement from the BBM to the basolateral membranes by binding proteins with high Ca(2+) affinity (such as CB9k); and Ca(2+) extrusion into the blood. Plasma membrane Ca(2+) ATPase (PMCA1b) and sodium calcium exchanger (NCX1) are mainly involved in the exit of Ca(2+) from enterocytes. A novel molecule, the 4.1R protein, seems to be a partner of PMCA1b, since both molecules co-localize and interact. The paracellular pathway consists of Ca(2+) transport through transmembrane proteins of tight junction structures, such as claudins 2, 12, and 15. There is evidence of crosstalk between the transcellular and paracellular pathways in intestinal Ca(2+) transport. When intestinal oxidative stress is triggered, there is a decrease in the expression of several molecules of both pathways that inhibit intestinal Ca(2+) absorption. Normalization of redox status in the intestine with drugs such as quercetin, ursodeoxycholic acid, or melatonin return intestinal Ca(2+) transport to control values. Calcitriol [1,25(OH)₂D₃] is the major controlling hormone of intestinal Ca(2+) transport. It increases the gene and protein expression of most of the molecules involved in both pathways. PTH, thyroid hormones, estrogens, prolactin, growth hormone, and glucocorticoids apparently also regulate Ca(2+) transport by direct action, indirect mechanism mediated by the increase of renal 1,25(OH)₂D₃ production, or both. Different physiological conditions, such as growth, pregnancy, lactation, and aging, adjust intestinal Ca(2+) absorption according to Ca(2+) demands. Better knowledge of the molecular details of intestinal Ca(2

  18. Molecular mechanisms involved in intestinal iron absorption

    Institute of Scientific and Technical Information of China (English)

    Paul Sharp; Surjit Kaila Srai

    2007-01-01

    Iron is an essential trace metal in the human diet due to its obligate role in a number of metabolic processes.In the diet, iron is present in a number of different forms, generally described as haem (from haemoglobin and myoglobin in animal tissue) and non-haem iron (including ferric oxides and salts, ferritin and lactoferrin).This review describes the molecular mechanisms that co-ordinate the absorption of iron from the diet and its release into the circulation. While many components of the iron transport pathway have been elucidated, a number of key issues still remain to be resolved. Future work in this area will provide a clearer picture regarding the transcellular flux of iron and its regulation by dietary and humoral factors.

  19. [Application of solid sampling graphite furnace atomic absorption spectrophotometry to mensuration of brain iron content in rats].

    Science.gov (United States)

    Zhang, Nan; Sheng, Qing-hai; Shi, Zhen-hua; Zhang, Zhi-guo; Duan, Xiang-lin; Chang, Yan-zhong

    2009-04-01

    In the present study, the authors performed the solid sampling and detected the iron levels in cortex, hippocampus and striatum of rat brain by GFAAS. The authors' results showed that there are no remarkable difference between the data obtained by solid sampling graphite furnace atomic absorption and liquid sampling graphite furnace atomic absorption. Compared to liquid sampling graphite furnace atomic absorption, the sample pre-treatment stage was obviously simplified, the cost was reduced significantly, and the time was shortened significantly in the solid sampling GFAAS. This study will be beneficial to the mensuration of iron content in micro-tissue of animal by solid sampling GFASS.

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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.

  2. Determination of β-lactam Antibiotics in Pharmaceutical Preparations by Uv-visible Spectrophotometry Atomic Absorption and High Performance Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    *A. J. Abdulghani

    2012-09-01

    Full Text Available The determination amoxicillin, ampicillin and cephalexin was studied by complexation of the antibiotics with Au(III and Hg(II ions in bulk and pharmaceutical preparations using uv-visible spectrophotometry, atomic absorption, and HPLC techniques. Optimum conditions for complex formation were fixed at pH 4 and (2-4 for Au(III and Hg(IIcomplexes respectively, heating temperature at (60 °C and heating time for (10 minute. All complexes were extracted from aqueous solution with benzyl alcohol prior to measurements except in the case of HPLC. The L:M ratios for all complexes were determined and stability constants were calculated using mole ratio method. The Beer's law was obeyed over the concentration range (5-60 and 5-50 µg/ml of antibiotics for Au(III and Hg(II complexes using colorimetric method and (1-25 µg/ml of Au(III for FAAS. The linearity for HPLC method was (10-110 and 10-120 µg/ml respectively. The correlation coefficients (r were (0.9981-0.9997. Generally, the highest sensitivity was recorded by FAAS.

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Science.gov (United States)

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

    2014-09-01

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

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

    Science.gov (United States)

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

    1990-07-01

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

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

    Science.gov (United States)

    Donaldson, E M

    1980-10-01

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

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

    Science.gov (United States)

    Donaldson, E M

    1980-06-01

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

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

    Science.gov (United States)

    Kashefiolasl, Sepide; Foerch, Christian; Pfeilschifter, Waltraud

    2013-02-15

    Intracerebral hemorrhage (ICH) accounts for 10% of all strokes and has a significantly higher mortality than cerebral ischemia. For decades, ICH has been neglected by experimental stroke researchers. Recently, however, clinical trials on acute blood pressure lowering or hyperacute supplementation of coagulation factors in ICH have spurred an interest to also design and improve translational animal models of spontaneous and anticoagulant-associated ICH. Hematoma volume is a substantial outcome parameter of most experimental ICH studies. We present graphite furnace atomic absorption spectrophotometric analysis (AAS) as a suitable method to precisely quantify hematoma volumes in rodent models of ICH. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Comparison determinations of gold in ore between atomic absorption spectrophotometry and hydroquinone volumetric method%原子吸收分光光度法与氢醌容量法测定矿石中金的比对

    Institute of Scientific and Technical Information of China (English)

    李玲

    2013-01-01

    Two kinds of analysis methods of gold in the ores are compared. The results show that, the atomic absorption spectrophotometry is better than the hydroquinone volumetric method.%本文对矿石中金的两种分析方法进行了比对。结果表明原子吸收分光光度法要优于氢醌容量法。

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

    Science.gov (United States)

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

    2000-01-01

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

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

    Science.gov (United States)

    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.

  12. [Ferric iron absorption in deltar p f F xoo, a gene deletion mutant of Xanthomonas oryzae pv. oryzae, assayed using atomic absorption spectrophotometry].

    Science.gov (United States)

    Sun, Lei; Wu, Mao-Sen; He, Chen-Yang

    2010-04-01

    The ferric iron absorption is one of the most important limiting factors of bacterial growth of Xanthomonas oryzae pv. oryzae. It has been previously speculated that r p f F xoo might be involved in the ferric iron metabolism of the pathogen. In the present study, deltar p f F xoo, a gene deletion mutant, was generated from the wild-type strain PXO99A of Xoo through the homologous recombination, and Fe content was assayed using flame atomic absorption in PXO99A and deltar p f F xoo. The results indicated that the recovery was 99.7% and the relative standard deviation was 1.89 under optimized AAS operating conditions. The increase in Fe absorption in PXO99A and deltar p f F xoo was observed with the increasing time. However, the ferric content of deltar p f F xoo was significantly lower than that of PXO99A (P < 0.05). It is suggested that r p f F xoo is involved in iron metabolism in Xanthomonas oryzae pv. oryzae.

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

    Science.gov (United States)

    Damrau, D.L.

    1993-01-01

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

  14. [Exploration of quality control of inorganic elements in Chinese herbal medicines for stimulating blood circulation and relaxing muscles and joints by atomic absorption spectrophotometry].

    Science.gov (United States)

    Zhang, Qi-feng; Fan, Mei-mei; Wang, Guan-min; Tu, Long-fei; Wang, Cheng

    2007-12-01

    Researches have shown the close relationships between inorganic elements and curative efficiencies of various Chinese herbal medicines. Yet, in studies of chemical composition and quality control of Chinese herbal medicines for stimulating blood circulation and relaxing muscles and joints, inorganic substances are often overlooked. In order to improve and reestablish the standard of quality control of Chinese herbal medicines, the authors attempted a method that would incorporate the composition of inorganic elements as part of the quality control. In the present study, the authors used atomic absorption spectrophotometry to measure the contents of fifteen inorganic elements, namely, Cu, Ca, Fe, K, Mg, Mo, Ni, Sr, V, Mn, Zn, Na, Cr, Cd, and Hg, in several Chinese herbal medicines, including Da Huo Luo Wan. The authors then discussed the relationship between these inorganic elements and curative efficiencies of these Chinese herbal medicines. By comparing the levels of inorganic elements found in Da Huo Luo Wan with those found in other Chinese herbal medicines used in the study, it was revealed that trace elements, Fe, Cu, Mn, and Zn, contribute to the curative efficiency of Da Huo Luo Wan. The authors' results showed that the amounts of trace elements Fe, Cu, Mn and Zn found in Chinese herbal medicine Da Huo Luo Wan are related to the following curative effects of Da Huo Luo Wan: relieving rheumatism, rectifying breathing and alleviating phlegm, stimulating blood circulation and relaxing muscles and joints. The measurement and analysis of inorganic elements in Da Huo Luo Wan will also provide evidences and references for the fingerprint establishment of Da Huo Luo Wan in the future.

  15. Intramolecular electron transfer versus substrate oxidation in lactoperoxidase: investigation of radical intermediates by stopped-flow absorption spectrophotometry and (9-285 GHz) electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Fielding, Alistair J; Singh, Rahul; Boscolo, Barbara; Loewen, Peter C; Ghibaudi, Elena M; Ivancich, Anabella

    2008-09-16

    We have combined the information obtained from rapid-scan electronic absorption spectrophotometry and multifrequency (9-295 GHz) electron paramagnetic resonance (EPR) spectroscopy to unequivocally determine the electronic nature of the intermediates in milk lactoperoxidase as a function of pH and to monitor their reactivity with organic substrates selected by their different accessibilities to the heme site. The aim was to address the question of the putative catalytic role of the protein-based radicals. This experimental approach allowed us to discriminate between the protein-based radical intermediates and [Fe(IV)=O] species, as well as to directly detect the oxidation products by EPR. The advantageous resolution of the g anisotropy of the Tyr (*) EPR spectrum at high fields showed that the tyrosine of the [Fe(IV)=O Tyr (*)] intermediate has an electropositive and pH-dependent microenvironment [g(x) value of 2.0077(0) at pH >or= 8.0 and 2.0066(2) at 4.0

  16. Giant absorption of light by molecular vibrations on a chip

    Science.gov (United States)

    Karabchevsky, A.; Kavokin, A. V.

    2016-01-01

    Vibrational overtone spectroscopy of molecules is a powerful tool for drawing information on molecular structure and dynamics. It relies on absorption of near infrared radiation (NIR) by molecular vibrations. Here we show the experimental evidence of giant enhancement of the absorption of light in solutions of organic molecules due to the switch from ballistic to diffusive propagation of light through a channel silicate glass waveguide. We also experimentally address a dynamics of absorption as a function of time of adsorption of the organic molecules on a waveguide. The observed enhancement in diffusion regime is by a factor of 300 in N-Methylaniline and by factor of 80 in Aniline compared to the expected values in the case of ballistic propagation of light in a waveguide. Our results underscore the importance of a guide surface modification and the disordered molecular nano-layer in enhancement of absorption by amines on engineered integrated system. PMID:26887658

  17. Giant absorption of light by molecular vibrations on a chip

    CERN Document Server

    Karabchvesky, A; Kavokin, A V; Zervas, M N; Wilkinson, J S; Lagoudakis, P G

    2015-01-01

    Vibrational overtone spectroscopy of molecules is a powerful tool for drawing information on molecular structure and dynamics. It relies on absorption of near infrared radiation (NIR) by molecular vibrations. Here we show the experimental evidence of giant enhancement of the absorption of light in solutions of organic molecules due to the switch from ballistic to diffusive propagation of light through a channel silicate glass waveguide. We also experimentally address a dynamics of absorption as a function of time of adsorption of the organic molecules on a waveguide. The observed enhancement in diffusion regime is by a factor of 300 in N-Methylaniline and by factor of 80 in Aniline compared to the expected values in the ballistic propagation of light in a waveguide. Our results underscore the importance of a guide surface modification and the disordered6 molecular nano-layer in enhancement of absorption by amines on engineered integrated system.

  18. Measuring cation transport by Na,K- and H,K-ATPase in Xenopus oocytes by atomic absorption spectrophotometry: an alternative to radioisotope assays.

    Science.gov (United States)

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

    2013-02-19

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

  19. Nonlinear Absorption and Refraction in Multilevel Organic Molecular System

    Institute of Scientific and Technical Information of China (English)

    LI Chun-Fei; DENG Xiao-Xu; WANG Yu-Xiao

    2000-01-01

    The nonlinear absorption and refraction in a multilevel organic molecular system is described by using the density matrix theory. The total absorptive coefficient of the system in the low-density case is equal to a linear sum of contributions from each energy level. Similarly, the total refractive index is equal to a linear sum of contributions from each energy level plus the refractive index of the vacuum. The absorption coefficient or refractive index due to each level is proportional to the population of that level, where the constant of proportionality is called the absorption cross-section or the refraction volume, respectively. The relation between the absorption cross-section and the refraction volume for each level is also given.

  20. Electronic absorption spectra and geometry of organic molecules an application of molecular orbital theory

    CERN Document Server

    Suzuki, Hiroshi

    1967-01-01

    Electronic Absorption Spectra and Geometry of Organic Molecules: An Application of Molecular Orbital Theory focuses on electronic absorption spectra of organic compounds and molecules. The book begins with the discussions on molecular spectra, electronic absorption spectra of organic compounds, and practical measures of absorption intensity. The text also focuses on molecular orbital theory and group theory. Molecular state functions; fundamental postulates of quantum theory; representation of symmetry groups; and symmetry operations and symmetry groups are described. The book also dis

  1. Molecular characterisation of non-absorptive and absorptive enterocytes in human small intestine

    DEFF Research Database (Denmark)

    Gassler, N; Newrzella, D; Böhm, C;

    2006-01-01

    BACKGROUND AND AIMS: Perturbation of differentiation of the crypt-villus axis of the human small intestine is associated with several intestinal disorders of clinical importance. At present, differentiation of small intestinal enterocytes in the crypt-villus axis is not well characterised. SUBJECTS...... genes, and vesicle/transport related genes was found. CONCLUSION: Two types of enterocytes were dissected at the molecular level, the non-absorptive enterocyte located in the upper part of crypts and the absorptive enterocyte found in the middle of villi. These data improve our knowledge about...... the physiology of the crypt-villus architecture in human small intestine and provide new insights into pathophysiological phenomena, such as villus atrophy, which is clinically important....

  2. Molecular absorption cryogenic cooler for liquid hydrogen propulsion systems

    Science.gov (United States)

    Klein, G. A.; Jones, J. A.

    1982-01-01

    A light weight, long life molecular absorption cryogenic cooler (MACC) system is described which can use low temperature waste heat to provide cooling for liquid hydrogen propellant tanks for interplanetary spacecraft. Detailed tradeoff studies were made to evaluate the refrigeration system component interactions in order to minimize the mass of the spacecraft cooler system. Based on this analysis a refrigerator system mass of 31 kg is required to provide the .48 watts of cooling required by a 2.3 meter diameter liquid hydrogen tank.

  3. Molecular absorption spectrometry in flames and furnaces: a review.

    Science.gov (United States)

    Butcher, David J

    2013-12-04

    Molecular absorption spectrometry (MAS), originally developed in the 1970s, is a technique to determine non-metals in flames and graphite furnaces by monitoring the absorbance of diatomic molecules. Early studies employed low resolution instruments designed for line source atomic absorption, which provided a limited choice of analytical wavelengths, insufficient spectral resolution, and spectral interferences. However, the development of high-resolution continuum source atomic absorption spectrometry (HR-CS AAS) instrumentation has allowed the analysis of challenging samples for non-metals as well as some difficult elements to determine by AAS, such as aluminum and phosphorus. In this review, theory and analytical considerations for MAS are discussed. The principles and limitations of low resolution MAS are described, along with its applications. HR-CS AAS instrumentation is reviewed, emphasizing performance characteristics most relevant for MAS. Applications of flame and HR-CS GFMAS are reviewed, highlighting the most significant work to date. The paper concludes with an evaluation of the enhanced analytical capabilities provided by HR-CS MAS. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Absorption from Diffuse Molecular Gas in the LMC

    Science.gov (United States)

    Welty, Dan; Murphy, Tara; Xue, Rui; Wong, Tony

    2011-04-01

    Observations of absorption from complex molecular species (e.g., HCO+, H2CO, HCN, C3H2, NH3) in the mm- and cm-wave spectra of extragalactic radio sources have revealed a surprisingly rich chemistry in relatively diffuse Galactic gas. Some of those same species have been detected, at redshifts z ~ 0.6-0.9, in similar spectra of several gravitationally lensed QSOs. It is not at all clear how such complex molecules are formed (and survive) in clouds characterized by such relatively low densities and extinctions. We propose to search for absorption from NH3 and C3H2 in the nearby, lower metallicity Large Magellanic Cloud, using ATCA/CABB observations of two of the brightest 20 GHz sources behind the main body of the LMC. Comparisons among the lowest NH3 inversion lines can yield estimates for the kinetic temperature in the gas; the ratio of linear- to cyclic-C3H2 can give an indication of the density. Via comparisons with existing observations of these species in our Galaxy and in several higher redshift systems, we aim to further understand (1) how complex molecules can be present in diffuse media, and (2) diffuse cloud chemistry and the atomic-to-molecular transition in lower metallicity systems.

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

    Science.gov (United States)

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

    1981-01-01

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

  6. DIFFUSE MOLECULAR CLOUD DENSITIES FROM UV MEASUREMENTS OF CO ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    Goldsmith, Paul F. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2013-09-10

    We use UV measurements of interstellar CO toward nearby stars to calculate the density in the diffuse molecular clouds containing the molecules responsible for the observed absorption. Chemical models and recent calculations of the excitation rate coefficients indicate that the regions in which CO is found have hydrogen predominantly in molecular form and that collisional excitation is by collisions with H{sub 2} molecules. We carry out statistical equilibrium calculations using CO-H{sub 2} collision rates to solve for the H{sub 2} density in the observed sources without including effects of radiative trapping. We have assumed kinetic temperatures of 50 K and 100 K, finding this choice to make relatively little difference to the lowest transition. For the sources having T{sup ex}{sub 10} only for which we could determine upper and lower density limits, we find (n(H{sub 2})) = 49 cm{sup -3}. While we can find a consistent density range for a good fraction of the sources having either two or three values of the excitation temperature, there is a suggestion that the higher-J transitions are sampling clouds or regions within diffuse molecular cloud material that have higher densities than the material sampled by the J = 1-0 transition. The assumed kinetic temperature and derived H{sub 2} density are anticorrelated when the J = 2-1 transition data, the J = 3-2 transition data, or both are included. For sources with either two or three values of the excitation temperature, we find average values of the midpoint of the density range that is consistent with all of the observations equal to 68 cm{sup -3} for T{sup k} = 100 K and 92 cm{sup -3} for T{sup k} = 50 K. The data for this set of sources imply that diffuse molecular clouds are characterized by an average thermal pressure between 4600 and 6800 K cm{sup -3}.

  7. Molecular Absorption in the Disk of GV Tau

    Science.gov (United States)

    Carr, John

    High resolution MIR spectroscopy with SOFIA offers the opportunity for unique insights into the chemical evolution of disks (e.g., the origin of prebiotic molecules) and planet formation processes. We propose to use EXES to measure molecular absorption in the edge-on protoplanetary disk of GV Tau N. The proposed observations will search for and characterize several molecules of astrobiological importance: water, formaldehyde (H2CO), and formic acid (HCOOH). The latter two simple molecules are potential chemical starting points for the synthesis of sugars, amino acids, and RNA. We will also search for SO2, which may be the dominant gas phase carrier of sulfur in disk atmospheres. Our observations will constrain the (poorly known) degree of sulfur depletion in disks, which bears on our understanding of the differentiation of the Earth's core. With the exception of water, little to nothing is known about these molecules in inner protoplanetary disks. Molecular column densities and relative abundances will be determined for comparison with chemical disk models and abundances in comets and the interstellar medium. In addition to lending new insights into the chemical evolution in the planet formation regions of protoplanetary disks, the observations will also serve as valuable pathfinder observations for JWST.

  8. Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs

    CERN Document Server

    Homeier, D; Allard, F; Hauschildt, P H; Schweitzer, A; Stancil, P C; Weck, P F; Homeier, Derek; Allard, Nicole F.; Allard, France; Hauschildt, Peter H.; Schweitzer, Andreas; Stancil, Phillip C.; Weck, Philippe F.

    2005-01-01

    Two peculiar stars showing an apparent extremely broadened and strong NaI D absorption have been discovered in surveys for cool white dwarfs by Oppenheimer et al. (2001) and Harris et al. (SDSS, 2003). We discuss the nature of these objects using PHOENIX atmosphere models for metal-poor brown dwarfs/very low mass stars, and new white dwarf LTE and NLTE models for hydrogen- and helium-dominated atmospheres with metals. These include complete molecular formation in chemical equilibrium and a model for the alkali resonance line broadening based on the damping profiles of Allard et al. (2003), as well as new molecular line opacities for metal hydrides. First results of our calculations indicate good agreement with a hydrogen-dominated WD atmosphere with a Na abundance roughly consistent with a state of high accretion. We analyse deviations of the abundances of Na, K, Mg and Ca from the cosmic pattern and comment on implications of these results for standard accretion scenarios.

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

    Donaldson, E M

    1981-07-01

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

  11. 石墨炉原子吸收光谱法测定植物油中砷%Determination of arsenic in vegetable oil by graphite furnace atomic absorption spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    俞涛; 蒋雪凤; 钟小伶

    2012-01-01

    Objective:To develop a method for the determination of arsenic in vegetable oil by graphite furnace a-tomic absorption spectrophotometry. Methods: After samples were digested with microwave, magnesium nitrate was added as matrix modifier and then determined by graphite furnace atomic absorption spectrometry. Results: The method had a linear relationship in the range of 0 μg/L ~ 20 μg/L ( r = 0. 9997) , and the detection limit was 0. 006 mg/kg, RSDs were between 2. 7% ~ 3. 2% ,the rate of recoveries were between 84. 7% ~99. 0% . Conclu-sion ; The method is simple, sensitive, reproducible and can be applicable to the determination of arsenic in vegeta-ble oil.%目的:建立检测植物油中砷含量的石墨炉原子吸收光谱方法.方法:样品经微波消化后,采用硝酸镁作为基体改进剂,石墨炉原子吸收光谱法测定.结果:方法线性范围为0 μg/L~ 20 μg/L,相关系数为0.9997,方法检出限为0.006 mg/kg,RSD为2.7%~3.2%,加标回收率为84.7%~99.0%.结论:本法简便、灵敏度高、重现性好,适用于植物油中砷的测定.

  12. Search for molecular absorptions with the Fourier Transform Spectrometer

    Science.gov (United States)

    Knacke, Roger F.

    1995-01-01

    The objective of this research was a search for water molecules in the gas phase in molecular clouds. Water should be among the most abundant gases in the clouds and is of fundamental importance in gas chemistry, cloud cooling, shock wave chemistry, and gas-grain interactions of interstellar dust. Detection of water in Comet Halley in the 2.7 micron v(3) band in 1986 had shown that airborne H2O observations are feasible (ground-based observations of H2O are impossible because of the massive water content of the atmosphere). We planned to observe the v(3) band in interstellar clouds where a number of lines of this band should be in absorption. The search for H2O commenced in 1988 with a two flight program on the KAO. this resulted in a detection of interstellar H2O with S/N of 2-4 in the v(3) 1(01)-2(02) line at 3801.42/cm. A subsequent flight series of two flights in 1989 resulted in confirmation to the 3801.42/cm line detection and the detection of altogether four strong lines in the 000-001 v(3) vibration-rotation band of H2O.

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

    Science.gov (United States)

    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.

  14. Determination of bismuth in ores, concentrates and non-ferrous alloys by atomic-absorption spectrophotometry after separation by diethyldithiocarbamate extraction or iron collection.

    Science.gov (United States)

    Donaldson, E M

    1979-12-01

    Two simple, reliable and moderately rapid atomic-absorption methods for determining trace and minor amounts of bismuth in copper, nickel, molybdenum, lead and zinc concentrates and ores, and in non-ferrous alloys, are described. These methods involve the separation of bismuth from matrix elements either by chloroform extraction of its diethyldithiocarbamate (DDTC) complex, at pH 11.5-12.0, from a sodium hydroxide medium containing citric acid, tartaric acid, EDTA and potassium cyanide as complexing agents, or by co-precipitation with hydrous ferric oxide from an ammoniacal medium. Bismuth is ultimately determined, at 223.1 nm after evaporation of the extract to dryness in the presence of nitric and petchloric acids and dissolution of the salts in 20% v/v hydrochloric acid, or by dissolution of the hydrous oxide precipitate with the same acid solution, respectively. Results obtained by both methods are compared with those obtained spectrophotometrically by the iodide method after the separation of bismuth by DDTC and xanthate extractions.

  15. 4-8 micron spectrophotometry of OH 0739-14

    Science.gov (United States)

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

    1981-01-01

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

  16. A novel lead imprinted polymer as the selective solid phase for extraction and trace detection of lead ions by flame atomic absorption spectrophotometry: Synthesis, characterization and analytical application

    Directory of Open Access Journals (Sweden)

    Homeira Ebrahimzadeh

    2017-05-01

    Full Text Available A novel ion imprinted polymer as the selective solid phase combined with flame atomic absorption spectrometry (FAAS was applied for preconcentration and determination of lead in real samples. In the first step, Pb(II-IIP was synthesized by copolymerization of 2-vinyl pyridine as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, 2,2-azobisisobutyronitrile as the initiator that imprinted with Pb(II as the template ion, 2-amino pyridine as the ligand. Subsequently, the imprinted Pb(II was completely removed by leaching the dried and powdered imprinted polymer with HCl (2 mol L−1. This polymer was characterized by Fourier Transform Infrared (FT-IR spectrometer. The effect of different variables on the extraction efficiency such as type and volume of eluent for extraction, solution’s pH for adsorption, sorption and desorption times was evaluated. Under the optimum conditions: type of eluent, HCl (2 mol L−1; volume of eluent, 5 mL; solution’s pH for sorption, 5; sorption time, 90 min; desorption time, 125 min and breakthrough volume of 750 mL were obtained. Preconcentration factor of the method was about 150. The limit of detection was obtained 0.75 μg L−1 and a dynamic linear range (DLR of 3–150 μg L−1 was found. The maximum sorption retention capacity of Pb(II ions on the imprinted polymer was 85.6 mg g−1. The prepared ion-imprinted polymer particles have an increased selectivity toward Pb(II ions over a range of competing metal ions with the same charge and similar ionic radius. Performance of the present method was evaluated for extraction and determination of Pb(II in water samples at microgram per liter concentration and satisfactory results were obtained (RSD = 2.7%.

  17. 石墨炉原子吸收光谱法测定胆固醇中镍的含量%Determination of nickel in cholesterol by graphite furnace atomic absorption spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    杨霞; 贺瑞玲; 闫中天; 杨锐; 栾琳; 王健; 林芷艺; 孙会敏

    2014-01-01

    目的:建立石墨炉原子吸收光谱法测定药用辅料胆固醇中镍的含量。方法:样品经硝酸-过氧化氢微波消解后用0.5%稀硝酸稀释,采用石墨炉原子吸收光谱法,以塞曼背景校正,标准曲线法测定。结果:该方法测定胆固醇中镍含量的线性范围20~100 mg · L -1,r=0.9973;检出限为0.4 mg · L -1;平均加样回收率为102.6%(n=9),RSD为3.9%。结论:方法快速、准确、可靠,适用于药用辅料胆固醇中镍含量的测定。%A method (graphite furnace atomic absorption spectrophotometry ,GFAAS ) for determina-tion of nickel in cholesterol was developed .The sample digested by microwave in nitric acid-hydrogen per-oxide and diluted by 0 .5% nitric acid .GFASS was used to analyze nickel in the sample ,corrected by Zee-man background and calculated by standard curve .The linear range was 20-100g · L -1 (r=0 .9973) .The detection limit of nickel was 0 .4mg · L -1 ,the average recovery was 102 .6% (n=9) ,and the relative stand-ard deviation(RSD) was 3 .9% .The method is rapid ,accurate ,reliable and suitable to determinen the nick-el in cholesterol .

  18. Determination of antimony in concentrates, ores and non-ferrous materials by atomic-absorption spectrophotometry after iron-lanthanum collection, or by the iodide method after further xanthate extraction.

    Science.gov (United States)

    Donaldson, E M

    1979-11-01

    Methods for determining trace and moderate amounts of antimony in copper, nickel, molybdenum, lead and zinc concentrates and in ores are described. Following sample decomposition, antimony is oxidized to antimony(V) with aqua regia, then reduced to antimony(III) with sodium metabisulphite in 6M hydrochloric acid medium and separated from most of the matrix elements by co-precipitation with hydrous ferric and lanthanum oxides. Antimony (>/= 100 mug/g) can subsequently be determined by atomic-absorption spectrophotometry, at 217.6 nm after dissolution of the precipitate in 3M hydrochloric acid. Alternatively, for the determination of antimony at levels of 1 mug/g or more, the precipitate is dissolved in 5M hydrochloric acid containing stannous chloride as a reluctant for iron(III) and thiourea as a complexing agent for copper. Then tin is complexed with hydrofluoric acid, and antimony is separated from iron, tin, lead and other co-precipitated elements, including lanthanum, by chloroform extraction of its xanthate. It is then determined spectrophotometrically, at 331 or 425 nm as the iodide. Interference from co-extracted bismuth is eliminated by washing the extract with hydrochloric acid of the same acid concentration as the medium used for extraction. Interference from co-extracted molybdenum, which causes high results at 331 nm, is avoided by measuring the absorbance at 425 nm. The proposed methods are also applicable to high-purity copper metal and copper- and lead-base alloys. In the spectrophotometric iodide method, the importance of the preliminary oxidation of all of the antimony to antimony(V), to avoid the formation of an unreactive species, is shown.

  19. Molecular shock response of explosives: electronic absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mcgrne, Shawn D [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory; Whitley, Von H [Los Alamos National Laboratory; Bolme, Cindy A [Los Alamos National Laboratory; Eakins, Daniel E [Los Alamos National Laboratory

    2009-01-01

    Electronic absorption spectroscopy in the range 400-800 nm was coupled to ultrafast laser generated shocks to begin addressing the question of the extent to which electronic excitations are involved in shock induced reactions. Data are presented on shocked polymethylmethacrylate (PMMA) thin films and single crystal pentaerythritol tetranitrate (PETN). Shocked PMMA exhibited thin film interference effects from the shock front. Shocked PETN exhibited interference from the shock front as well as broadband increased absorption. Relation to shock initiation hypotheses and the need for time dependent absorption data (future experiments) is briefly discussed.

  20. Determination of cadmiumcontent in honeysuckle by chemical atomizeratomic absorption spectrophotometry%化学原子化-原子吸收光谱法测定金银花中镉含量的方法研究

    Institute of Scientific and Technical Information of China (English)

    刘利敏; 罗亚虹; 李琦; 龚治湘

    2013-01-01

    目的:采用化学原子化-原子吸收光谱法,建立金银花中重金属镉的测定方法.方法:采用PE-AA400原子吸收分光光度计,MCA-201微型化学原子化器,波长228.8 nm,狭缝2.7 mm/1.35 mm,灯电流4mA,氩气流量为1.2 L.min-1.结果:镉浓度在0.1 ~8.0 μg·L-1范围内,具有良好的线性关系,校准方程为A =0.1356C +0.0117(r =0.9998);方法回收率(n=9)为95.5%.结论:化学原子化-原子吸收光谱法测定金银花中痕量镉,灵敏度高,无背景影响,操作简单快速,成本低廉.%Objective: To establish a chemical atomizeratomic absorption spectrophotometry(AAS)method for determination of cadmium content in honeysuckle. Methods: The contents of cadmium were measured by PE - AA400 a-tomic absorption spectrophotometer and Mini - chemical Atomizer MCA - 201 at the wavelength of 228. 8 nm. Entrance slit was 2. 7 mm/1. 35 mm,lamp current was 4 mA,and the flow of argon was 1. 2 L · min-1 . Results: A good linear relationship was observed when he cadmium concentration ranged in 0. 1 ~8. 0 μg · mL-1 ,with the calibrator equation A = 0. 1356C + 0. 0117( r = 0. 9998); The recovery ( n = 9 ) was 95. 5%. Conclusion: The established method has a high sensitivity with no influential background,it is also easy -to -operate and with low cost.

  1. Absorption enhancing effects of chitosan oligomers on the intestinal absorption of low molecular weight heparin in rats.

    Science.gov (United States)

    Zhang, Hailong; Mi, Jie; Huo, Yayu; Huang, Xiaoyan; Xing, Jianfeng; Yamamoto, Akira; Gao, Yang

    2014-05-15

    Absorption enhancing effects of chitosan oligomers with different type and varying concentration on the intestinal absorption of low molecular weight heparin (LMWH) were examined by an in situ closed loop method in different intestinal sections of rats. Chitosan hexamer with the optimal concentration of 0.5% (w/v) showed the highest absorption enhancing ability both in the small intestine and large intestine. The membrane toxicities of chitosan oligomers were evaluated by morphological observation and determining the biological markers including amount of protein and activity of lactate dehydrogenase (LDH) released from intestinal epithelium cells. There was no obvious change both in levels of protein and LDH and morphology in the intestinal membrane between control and various chitosan oligomers groups, suggesting that chitosan oligomers did not induce any significant membrane damage to the intestinal epithelium. In addition, zeta potentials became less negative and amount of free LMWH gradually decreased when various chitosan oligomers were added to LMWH solution, revealing that electrostatic interaction between positively charged chitosan oligomers and negative LMWH was included in the absorption enhancing mechanism of chitosan oligomers. In conclusion, chitosan oligomers, especially chitosan hexamer, are safe and efficient absorption enhancers and can be used promisingly to improve oral absorption of LMWH.

  2. Determination of Tetraethyl Lead in Water by Hydride Generation-Atomic Absorption Spectrophotometry%水中痕量铜的SBA-15修饰碳糊电极溶出伏安测定法

    Institute of Scientific and Technical Information of China (English)

    杨振兴

    2011-01-01

    Objective To establish a method for the determination of tetraethyl lead in water by hydride generation-atomic absorption spectrophotometry. Methods By solvent extraction of trichloromethane and low-temperature degradation,the best optimum experimental condition of optimal design of orthogonal test: wavelength was 217 nm, lamp current was 3.0 mA, band pass was 0.2 nm, supporting gas was argon GAS (99.99%), argon gas flux was 0.8 L/min, peak height measurement, oxidizing flame, 20 g/L NaBH4 solution,5 mi HNO3 (1.42 g/mi) solution, 1.5 ml HCl(1.19 g/ml) solution, 100 g/L K3Fe(CN)6 solution. Results The limit of detection was 0.049 μg/L,the average recovery rates were 89.7%-101.4% and RSDs were 3.3%-5.3%. Conclusion This method is simple, sensitive, accurate and applicable to the determination of the tetraethyl lead in water.%目的 建立介孔材料修饰碳糊电极测定水中痕量铜的方法.方法 制备SBA-15修饰碳糊电极,并在pH值为4.2的乙酸-乙酸钠缓冲溶液中,采用溶出伏安法对水中痕量铜进行测定.结果 优化实验条件下,相关系数达到0.997 3,测得Cu2+的线性范围和最低检出限分别为2.0×10-10~4.0×10-8mol/L和1.0×10-10mol/L,样品加标回收率为97.0%~101.8%.结论该方法简单、快速、灵敏,可用于实际水样中痕量铜的测定.

  3. Cuantificación de Cobre en Polifenoloxidasa de Frutas Tropicales por Espectrofotometría de Absorción Atómica Copper Quantification on Tropical Fruits by Atomic Absorption Spectrophotometry

    Directory of Open Access Journals (Sweden)

    María E Jiménez-Vieyra

    2011-01-01

    Full Text Available Este estudio cuantifica el contenido de cobre en aguacate y su pH en ciruela, fresa, kiwi, mamey, mango, manzana, pera y plátano. También cobre en la enzima polifenoloxidasa y velocidad de obscurecimiento. El cobre se determinó mediante espectrofotometría de absorción atómica en muestras digeridas por vía húmeda. El aguacate tuvo más cobre en enzimas (0.059 mg con mayor velocidad de obscurecimiento (0.751 s"¹; la fresa tuvo la menor cantidad de cobre (0.016 mg y la menor velocidad de reacción (0.115 s"¹. Las frutas con pH más ácido tuvieron contenido medio de cobre en la enzima y el menor obscurecimiento. La pera y el plátano tuvieron velocidad de reacción (0.3 y pH similares pero contenidos diferentes de cobre. Los resultados permiten establecer una correlación directa entre el contenido de cobre en enzimas y la velocidad obscurecimiento.This work quantifies the copper content in avocado and pH in, plum, strawberry, kiwi, mamey sapote, mango, apple, pear and banana. Copper and browning rate on enzymes of those fruits were also determined. Copper content was measured by atomic absorption spectrophotometry on samples digested by wet-chemical method. Avocados had the highest content of copper on enzymes (0.059 mg with the highest browning rate (0.751 s"¹ while strawberries had the lowest copper content (0.016 mg and the lowest browning rate (0.115 s"¹. Fruits with acid pH had acceptable copper content on the enzyme and a low browning rate. Pears and bananas had similar pH and browning rate (0.3 with different copper contents. The results do not allow establishing a direct relationship between copper content in enzymes and its browning rate.

  4. Porous carbon nanotubes: Molecular absorption, transport, and separation

    Science.gov (United States)

    Yzeiri, Irena; Patra, Niladri; Král, Petr

    2014-03-01

    We use classical molecular dynamics simulations to study nanofluidic properties of porous carbon nanotubes. We show that saturated water vapor condenses on the porous nanotubes, can be absorbed by them and transported in their interior. When these nanotubes are charged and placed in ionic solutions, they can selectively absorb ions in their interior and transport them. Porous carbon nanotubes can also be used as selective molecular sieves, as illustrated on a room temperature separation of benzene and ethanol.

  5. Determination of Calcium in Chinese Distillate Spirits Using Direct Sampling-Flame Atomic Absorption Spectrophotometry%直接进样火焰原子吸收光谱法测定白酒中的钙

    Institute of Scientific and Technical Information of China (English)

    刘全德; 陈尚龙; 李勇; 郑毅; 黄小冬; 王锋

    2011-01-01

    建立采用标准曲线法进行定量,火焰原子吸收光谱法(flame atomic absorption spectrophotometry,FAAS)直接进样测定白酒中钙的方法。探讨反应体系、释放剂浓度、乙炔流量以及燃烧器高度对吸光度的影响,比较两种定量方式对测定结果的影响。结果表明,利用体积分数50%乙醇溶液作为标准酒样可以有效地消除因匹配而产生的误差,因此,实验选择标准曲线法作为定量方式。在最佳的实验条件下,钙的线性范围为0.2~8μg/mL,检出限为0.17μg/mL,白酒中钙的质量浓度为9.73μg/mL,精密度为2.04%,加标平均回收率为101.5%,RSD为2.7 3%。该方法直接、快速、准确、稳定,具有较高的实用价值。%A flame atomic absorption spectrophotometric(FAAS) method to determine calcium in Chinese distillate spirits was presented without the need for sample pretreatment.The effects of reaction system composition,releasing agent concentration,acetylene flow rate and burner height on the absorbance at 422.7 nm of the reaction system were explored.Quantification methods such as standard curve method and standard addition method were compared for their effects on calcium quantification.Our results illustrated that the error caused by incompatibility could be eliminated by using 50% aqueous ethanol as standard sample.Therefore,the standard curve method was selected for calcium quantification.Under the optimal conditions,the linear range of quantification of the method was 0.2-8μg/mL,with a detection limit of 0.17μg/mL.The calcium content of a certain commercial sample was determined by the method to be 9.73μg/mL,and the precision RSD for 6 parallel determinations was 2.04%.The average spike recovery across three levels was 101.5% with a relative standard deviation of 2.73%.The method was direct,rapid,accurate and stable and had great value for practical applications.

  6. Effect of Pressure Broadening on Molecular Absorption Cross Sections in Exoplanetary Atmospheres

    CERN Document Server

    Hedges, Christina

    2016-01-01

    Spectroscopic observations of exoplanets are leading to unprecedented constraints on their atmospheric compositions. However, molecular abundances derived from spectra are degenerate with the absorption cross sections which form critical input data in atmospheric models. Therefore, it is important to quantify the uncertainties in molecular cross sections to reliably estimate the uncertainties in derived molecular abundances. However, converting line lists into cross sections via line broadening involves a series of prescriptions for which the uncertainties are not well understood. We investigate and quantify the effects of various factors involved in line broadening in exoplanetary atmospheres - the profile evaluation width, pressure versus thermal broadening, broadening agent, spectral resolution, and completeness of broadening parameters - on molecular absorption cross sections. We use H$_2$O as a case study as it has the most complete absorption line data. For low resolution spectra (R$\\lesssim$100) for re...

  7. Analysis of Nitrogen in Sodium by Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Sodium sample in which nitrogen exists in form of sodium nitride, lithium nitride and calcium nitrideis solved by distilled water and produce ammonia. Ammonia is relieved when solution is heated, then it isabsorbed by hydrochloric acid to produce ammnium chloride. In alkaline solution, ammonium chlorideconverts into ammonia. Ammonia reacts with hypochlorite and phenol that produces a blue indophenol.Nitrogen is determined by 751G type spectrophotometry at the absorption wavelength of 635 nm. The work condition of 751G type spectroscopy, colorimetric condition, smicture of the apparatus

  8. Quantification of the fluorine containing drug 5-fluorouracil in cancer cells by GaF molecular absorption via high-resolution continuum source molecular absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Magnus [Freie Universitaet Berlin, Institut fuer Pharmazie, Pharmazeutische Chemie, Koenigin-Luise-Str. 2-4, 14195 Berlin (Germany); Huang, Mao-Dong; Becker-Ross, Helmut; Florek, Stefan [Leibniz Institut fuer Analytische Wissenschaften, ISAS-e.V., Department Berlin, Albert-Einstein-Str. 9, 12489 Berlin (Germany); Ott, Ingo [Technische Universitaet Carolo Wilhelmina zu Braunschweig, Institut fuer Medizinische und Pharmazeutische Chemie, Beethovenstr. 55, 38106 Braunschweig (Germany); Gust, Ronald, E-mail: ronald.gust@uibk.ac.at [Universitaet Innsbruck, Institut fuer Pharmazie, Pharmazeutische Chemie, Innrain 80/82, 6020 Innsbruck (Austria)

    2012-03-15

    The development of high-resolution continuum source molecular absorption spectrometry made the quantification of fluorine feasible by measuring the molecular absorption as gallium monofluoride (GaF). Using this new technique, we developed on the example of 5-fluorouracil (5-FU) a graphite furnace method to quantify fluorine in organic molecules. The effect of 5-FU on the generation of the diatomic GaF molecule was investigated. The experimental conditions such as gallium nitrate amount, temperature program, interfering anions (represented as corresponding acids) and calibration for the determination of 5-FU in standard solution and in cellular matrix samples were investigated and optimized. The sample matrix showed no effect on the sensitivity of GaF molecular absorption. A simple calibration curve using an inorganic sodium fluoride solution can conveniently be used for the calibration. The described method is sensitive and the achievable limit of detection is 0.23 ng of 5-FU. In order to establish the concept of 'fluorine as a probe in medicinal chemistry' an exemplary application was selected, in which the developed method was successfully demonstrated by performing cellular uptake studies of the 5-FU in human colon carcinoma cells. - Highlights: Black-Right-Pointing-Pointer Development of HR-CS MAS for quantification of fluorine bound to organic molecules Black-Right-Pointing-Pointer Measuring as molecular absorption of gallium monofluoride Black-Right-Pointing-Pointer Quantification of organic-bound fluorine in biological material Black-Right-Pointing-Pointer The concept of 'fluorine as a probe in medicinal chemistry' could be established.

  9. Absorption of infra-red radiation by atmospheric molecular cluster-ions

    OpenAIRE

    Aplin, K. L.; R. A. McPheat

    2005-01-01

    Protonated water clusters are a common species of atmospheric molecular cluster-ion, produced by cosmic rays throughout the troposphere and stratosphere. Under clear-sky conditions or periods of increased atmospheric ionisation, such as solar proton events, the IR absorption by atmospheric ions may affect climate through the radiative balance. Fourier Transform Infrared Spectrometry in a long path cell, of path length 545m, has been used to detect IR absorption by corona-generated positive mo...

  10. Quantification of the fluorine containing drug 5-fluorouracil in cancer cells by GaF molecular absorption via high-resolution continuum source molecular absorption spectrometry

    Science.gov (United States)

    Krüger, Magnus; Huang, Mao-Dong; Becker-Roß, Helmut; Florek, Stefan; Ott, Ingo; Gust, Ronald

    The development of high-resolution continuum source molecular absorption spectrometry made the quantification of fluorine feasible by measuring the molecular absorption as gallium monofluoride (GaF). Using this new technique, we developed on the example of 5-fluorouracil (5-FU) a graphite furnace method to quantify fluorine in organic molecules. The effect of 5-FU on the generation of the diatomic GaF molecule was investigated. The experimental conditions such as gallium nitrate amount, temperature program, interfering anions (represented as corresponding acids) and calibration for the determination of 5-FU in standard solution and in cellular matrix samples were investigated and optimized. The sample matrix showed no effect on the sensitivity of GaF molecular absorption. A simple calibration curve using an inorganic sodium fluoride solution can conveniently be used for the calibration. The described method is sensitive and the achievable limit of detection is 0.23 ng of 5-FU. In order to establish the concept of "fluorine as a probe in medicinal chemistry" an exemplary application was selected, in which the developed method was successfully demonstrated by performing cellular uptake studies of the 5-FU in human colon carcinoma cells.

  11. Determination of Tetraethyl Lead in Water by Hydride Generation-Atomic Absorption Spectrophotometry%水中四乙基铅的氢化原子吸收测定法

    Institute of Scientific and Technical Information of China (English)

    公丕峰

    2011-01-01

    Objective To establish a method for the determination of tetraethyl lead in water by hydride generation-atomic absorption spectrophotometry. Methods By solvent extraction of trichloromethane and low-temperature degradation,the best optimum experimental condition of optimal design of orthogonal test: wavelength was 217 nm, lamp current was 3.0 mA, band pass was 0.2 nm, supporting gas was argon GAS (99.99%), argon gas flux was 0.8 L/min, peak height measurement, oxidizing flame, 20 g/L NaBH4 solution,5 ml HNO3 (1.42 g/ml) solution, 1.5 ml HCl(1.19 g/ml) solution, 100 g/L K3Fe(CN)6 solution. Results The limit of detection was 0.049 μg/L,the average recovery rates were 89.7%-101.4% and RSDs were 3.3%-5.3%. Conclusion This method is simple, sensitive, accurate and applicable to the determination of the tetraethyl lead in water.%目的 建立水中四乙基铅的氢化原子吸收测定方法.方法 样品经三氯甲烷萃取,低温消解后,采用氢化原子吸收法进行分析.经正交设计优化后的试验条件:波长为217.0 nm,灯电流为3.0 mA,光谱通带为0.2 nm;载气为99.99%氩气,载气流量为0.8 L/min,测量方式为峰高,氧化性蓝色焰,NaBH4溶液浓度为20g/L,1.42g/ml硝酸用量为5 ml,1.19g/ml盐酸用量为1.5 ml,K3Fe(CN)6溶液浓度为100g/L.结果 在0.049~100μg/L线性范围内,所得四乙基铅的标准曲线回归方程为γ=1.07×10-34+3.49×10-3x,相关系数为0.999 6.该方法的检出限为0.049 μg/L,平均回收率为89.7%~101.4%,RSD为3.3%~53%.结论该方法操作方便,所用试验装置价格低廉,灵敏度和准确度均较高,适合各级单位用于水中四乙基铅的测定.

  12. Speciation Analysis of Calcium in Milk by Flame Atomic Absorption Spectrophotometry%火焰原子吸收光谱法测定牛奶中不同化学形态的钙

    Institute of Scientific and Technical Information of China (English)

    宋慧; 陈尚龙; 李超; 巫永华; 王锋; 黄小冬; 陈华云

    2012-01-01

    建立火焰原子吸收光谱法测定牛奶中不同化学形态钙的方法。研究乙醇体积分数、离心温度、离心力和离心时间对蛋白沉淀效果的影响,确定最佳分离条件,即乙醇体积分数50%、离心温度2℃、离心力6000×g、离心时间6min,建立沉淀剂分离牛奶中元素结合态和非结合态的方法。探讨释放剂硝酸镧的质量浓度对吸光度的影响,确定最佳质量浓度为6.00mg/mL。在此条件下,测定牛奶中总钙的质量浓度为808.6μg/mL,其中结合态钙的质量浓度为641.8μg/mL,占总钙的质量分数为79.4%;非结合态钙的质量浓度为173.0μg/mL,占总钙的质量分数为21.4%。本法的精密度(RSD)小于3.3%,仪器检出限为0.11μg/mL,加标平均回收率为97.0%,RSD为1.7%。该方法准确、稳定,具有较高的实用价值。%An effective method was developed for speciation analysis of calcium in milk by flame atomic absorption spectrophotometry.The effects of ethanol concentration,centrifuge temperature,centrifugal force and centrifugation time on protein sedimentation were discussed.The best conditions for separating calcium from samples were found to be protein sedimentation with 50% and centrifugation at 2 ℃ and 6000 × g for 6 min.The best La(NO3)3 concentration for releasing bound calcium was 6.00 mg/mL as determined by analyzing the effect on absorbance.Under the optimized conditions,the total calcium concentration of milk was determined to be 808.6 μg/mL and the bound and free calcium concentrations were 641.8 μg/mL and 173.0 μg/mL,which accounted for 79.4% and 21.4% of the total calcium,respectively.The precision(RSD) of the developed method was less than 3.3%,and the limit of detection was 0.11 μg/mL.The average spike recoveries of calcium was 97.0% with a RSD of 1.7%.This method was accurate,stable and applicable.

  13. Spectral properties of molecular iodine absorption cells filled to saturation pressure

    Science.gov (United States)

    Hrabina, Jan; Sarbort, Martin; Cip, Ondrej; Lazar, Josef

    2014-05-01

    The absorption cells - optical frequencies references - represent the crucial part of setups for practical realization of the meter unit - highly stable laser standards, where varied laser sources are frequency locked to the selected absorption transitions. Furthermore, not only in the most precise laboratory instruments, but also in less demanding interferometric measuring setups the frequency stabilization of the lasers throught the absorption in suitable media ensure the direct traceability to the fundamental standard of length. We present the results of measurement and evaluation of spectral properties of molecular iodine absorption cells filled to saturation pressure of absorption media. A set of cells filled with different amounts of molecular iodine was prepared and an agreement between expected and resulting spectral properties of these cells was observed and evaluated. The cells made of borosilicate glass instead of common fused silica were tested for their spectral properties in greater detail with special care for the absorption media purity - the measured hyperfine transitions linewidths were compared to cells traditionally made of fused silica glass with well known iodine purity. The usage of borosilicate glass material represents easier manufacturing process and also significant costs reduction but a great care must be taken to control/avoid the risk of absorption media contamination. An approach relying on measurement of linewidth of the hyperfine transitions is proposed and discussed.

  14. Equilibrium Structures and Absorption Spectra for SixOy Molecular Clusters using Density Functional Theory

    Science.gov (United States)

    2017-05-05

    frequencies within the IR and UV - visible ranges. The absorption spectrum corresponding to excitation states of SixOy-nH2O molecular clusters consisting of...Energies and IR Spectra……………………….......................….4 DFT Calculation of UV -Vis Spectra………………………………………………………….……5 Conclusion...calculation of approximate UV -Vis absorption spectra for SixOy molecular clusters, which uses time-dependent density functional theory (TD-DFT) as

  15. An ALMA Early Science survey of molecular absorption lines toward PKS1830-211 -- Analysis of the absorption profiles

    CERN Document Server

    Muller, S; Guelin, M; Gerin, M; Aalto, S; Beelen, A; Black, J H; Curran, S J; Darling, J; Dinh-V-Trung,; Garcia-Burillo, S; Henkel, C; Horellou, C; Martin, S; Marti-Vidal, I; Menten, K M; Murphy, M T; Ott, J; Wiklind, T; Zwaan, M A

    2014-01-01

    We present the first results of an ALMA spectral survey of strong absorption lines for common interstellar species in the z=0.89 molecular absorber toward the lensed blazar PKS1830-211. The dataset brings essential information on the structure and composition of the absorbing gas in the foreground galaxy. In particular, we find absorption over large velocity intervals (gtrsim 100 km/s) toward both lensed images of the blazar. This suggests either that the galaxy inclination is intermediate and that we sample velocity gradients or streaming motions in the disk plane, that the molecular gas has a large vertical distribution or extraplanar components, or that the absorber is not a simple spiral galaxy but might be a merger system. The number of detected species is now reaching a total of 42 different species plus 14 different rare isotopologues toward the SW image, and 14 species toward the NE line-of-sight. The abundances of CH, H2O, HCO+, HCN, and NH3 relative to H2 are found to be comparable to those in the G...

  16. High-Sensitivity Spectrophotometry.

    Science.gov (United States)

    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.…

  17. Rapid amorphization of molecular crystals by absorption of solvent molecules in the presence of hydrophilic matrices

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, S., E-mail: nakayama@nara-m.co.j [Technofarm Axesz Co., Ltd., 3-45-4 Kamiishihara, Chofu, Tokyo 182-0035 (Japan); Nara Machinery Co., Ltd., 2-5-7 Jounan-jima, Tokyo 143-0002 (Japan); Watanabe, T. [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522 (Japan); Senna, M. [Technofarm Axesz Co., Ltd., 3-45-4 Kamiishihara, Chofu, Tokyo 182-0035 (Japan); Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522 (Japan)

    2009-08-26

    Two organic molecular crystalline species, ibuprophen (IB) and indomethacine (IM) were subjected to methanol absorption in the presence of hydrophilic organic matrix, hydroxypropyl methylcellulose (HPMC). While spraying of 8-10% methanol or water on the drug-matrix mixture decreased the subsequent milling time for amorphization, absorption of methanol in a closed container caused spontaneous amorphization of IB was observed to give a nanocomposites with macroscopic agglomerates up to 250 mum after methanol absorption for overnight. Gentle mechanical homogenization under saturated methanol vapor with a newly developed apparatus, a tandem rotation mill (TRM), brought about homogeneous grains of IB-HPMC nanocomposites with the average particle size, 30 mum. We observed amorphous particles of IB in 60 nm regime dispersed in HPMC matrix under a transmission electron microscope (TEM). In the case of IM, mechanical homogenization with TRM was indispensable to obtain similar nanocomposites with HPMC.

  18. On the dynamic and static manifestation of molecular absorption in thin films probed by a microcantilever

    Energy Technology Data Exchange (ETDEWEB)

    Finot, Eric [Institut CARNOT de Bourgogne; Fabre, Arnaud [French Atomic Energy Commission (CEA), Centre de Valduc, Is-sur-Tille; Passian, Ali [ORNL; Thundat, Thomas [University of Alberta, Edmonton, Canada

    2014-03-01

    Mechanical resonators shaped like microcantilevers have been demonstrated as a platform for very sensitive detection of chemical and biological analytes. However, its use as an analytical tool will require fundamental understanding of the molecular absorption-induced effects in the static and dynamic sensor response. The effect of absorption-induced surface stress on the microcantilever response is here investigated using palladium hydride formation. It is shown that the resonance and deformation states of the cantilever monitored simultaneously exhibit excellent correlation with the phase of the hydride formation. However, the associated frequency shifts and quasistatic bending are observed to be independent during solid solution phase. Importantly, absorption-induced changes in the elastic parameters of the palladium film are found to play a dominant role in the static and dynamic response. The presented results help in discerning the parameters that control the cantilever response as well as the relationships between these parameters.

  19. Determination of Pb Interference and Elimination in DCP Feed with Flame Atomic Absorption Spectrophotometry%火焰原子吸收分光光度法测定饲料磷酸氢钙中的Pb的干扰及其消除

    Institute of Scientific and Technical Information of China (English)

    龚联军; 胡必明; 金岚

    2013-01-01

    空气要乙炔火焰原子吸收分光光度法测定饲料磷酸氢钙中的Pb存在背景吸收干扰,背景干扰大小与分析测试条件密切相关,确定了背景吸收干扰主要是由水溶液中大量的Ca2+、Mg2+和H3PO4引起,探讨了非吸收线(Pb282.3nm、Pb280.1nm)和连续光源(氘灯)扣除背景吸收的情况;提出以实现标准溶液与待测样品溶液“基体一致”的方法,避免了测定背景吸收。此法测定饲料磷酸氢钙样品中的Pb,操作简便快速,适宜限量测定。%There is background absorption interference in the determination of Pb in DCP feed with air-acetylene flame atomic absorption spectrophotometry. The strength of background interference is closely related to the anlaysis condition, and this paper ensures that the background absorption interference is mainly caused by Ca2+,Mg2+and H3PO4 in water solution.This paper discusses the cases of non-absorption line (Pb282.3nm, Pb280.1nm) and continuous light source (deuterium lamp) offseting background absorption and put forwards the way to achieve the standard solution and the sample solution "matrix consistent" which avoids the determination of background absorption. This method is easy and fast to carry out Pb determination in the DCP feed and it is fit for limit determination.

  20. Absorption of infra-red radiation by atmospheric molecular cluster-ions

    CERN Document Server

    Aplin, K L

    2005-01-01

    Protonated water clusters are a common species of atmospheric molecular cluster-ion, produced by cosmic rays throughout the troposphere and stratosphere. Under clear-sky conditions or periods of increased atmospheric ionisation, such as solar proton events, the IR absorption by atmospheric ions may affect climate through the radiative balance. Fourier Transform Infrared Spectrometry in a long path cell, of path length 545m, has been used to detect IR absorption by corona-generated positive molecular cluster-ions. The column concentration of ions in the laboratory spectroscopy experiment was estimated to be ~10^13 m-2; the column concentration of protonated atmospheric ions estimated using a simple model is ~10^14 m-2. Two regions of absorption, at 12.3 and 9.1 um are associated with enhanced ion concentrations. After filtering of the measured spectra to compensate for spurious signals from neutral water vapour and residual carbon dioxide, the strongest absorption region is at 9.5 to 8.8 um (1050 to 1140 cm-1)...

  1. Molecular modeling of C 60:cobaltocene and nickelocene complexes, comparison with IR absorption

    Science.gov (United States)

    Byszewski, P.; Antonova, K.; Kowalska, E.; Radomska, J.; Baran, J.

    2000-06-01

    C 60 was reacted with cobaltocene and nickelocene. The samples of the composition C 60(Cocp 2) 3 and C 60Nicp 2 were obtained in the reaction. Their thermal stability was measured by Thermogravimetry and Differential Scanning Calorimetry and the vibrational spectrum was investigated by infrared absorption. Hydrocarbon groups may be evacuated from the reaction products by annealing, while metal atoms remain dispersed between fullerenes. The experiments are compared with the molecular modeling results obtained by applying the PM3 model.

  2. The far-IR spectrum of Sagittarius B2 region: Extended molecular absorption, photodissociation and photoionization

    OpenAIRE

    Goicoechea, J. R.; Rodriguez-Fernandez, N. J.; Cernicharo, J.

    2003-01-01

    We present large scale 9'x 27'(25 pc x 70 pc) far-IR observations around Sgr B2 using the Long-wavelength spectrometer (LWS) on board the Infrared Space Observatory (ISO). The spectra are dominated by the strong continuum emission of dust, the widespread molecular absorption of light hydrides (OH, CH and H2O) and the fine structure lines of [NII], [NIII], [OIII], [CII] and [OI]. The molecular richness in the outer layers of Sgr B2 is probed by the ISO-LWS Fabry-Perot (35 km s^-1) detections t...

  3. Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: a ubiquitous tracer of molecular gas

    CERN Document Server

    Sonnentrucker, P; Phillips, T G; Gerin, M; Lis, D C; De Luca, M; Goicoechea, J R; Black, J H; Bell, T A; Boulanger, F; Cernicharo, J; Coutens, A; Dartois, E; Kazmierczak, M; Encrenaz, P; Falgarone, E; Geballe, T R; Giesen, T; Godard, B; Goldsmith, P F; Gry, C; Gupta, H; Hennebelle, P; Herbst, E; Hily-Blant, P; Joblin, C; Kolos, R; Krelowski, J; Mart\\in-Pintado, J; Menten, K M; Monje, R; Mookerjea, B; Pearson, J; Perault, M; Persson, C M; Plume, R; Salez, M; Schlemmer, S; Schmidt, M; Stutzki, J; Teyssier, D; Vastel, C; Yu, S; Caux, E; Gusten, R; Hatch, W A; Klein, T; Mehdi, I; Morris, P; Ward, J S

    2010-01-01

    We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1 - 0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH)-N(H2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF abs...

  4. Molecular dynamics study of a CNT-buckyball-enabled energy absorption system.

    Science.gov (United States)

    Chen, Heng; Zhang, Liuyang; Becton, Matthew; Nie, Hong; Chen, Jinbao; Wang, Xianqiao

    2015-07-14

    An energy absorption system (EAS) composed of a carbon nanotube (CNT) with nested buckyballs is put forward for energy dissipation during impact owing to the outstanding mechanical properties of both CNTs and buckyballs. Here we implement a series of molecular dynamics (MD) simulations to investigate the energy absorption capabilities of several different EASs based on a variety of design parameters. For example, the effects of impact energy, the number of nested buckyballs, and of the size of the buckyballs are analyzed to optimize the energy absorption capability of the EASs by tuning the relevant design parameters. Simulation results indicate that the energy absorption capability of the EAS is closely associated with the deformation characteristics of the confined buckyballs. A low impact energy leads to recoverable deformation of the buckyballs and the dissipated energy is mainly converted to thermal energy. However, a high impact energy yields non-recoverable deformation of buckyballs and thus the energy dissipation is dominated by the strain energy of the EAS. The simulation results also reveal that there exists an optimal value of the number of buckyballs for an EAS under a certain impact energy. Larger buckyballs are able to deform to a larger degree yet also need less impact energy to induce plastic deformation, therefore performing with a better overall energy absorption ability. Overall, the EAS in this study shows a remarkably high energy absorption density of 2 kJ g(-1), it is a promising candidate for mitigating impact energy and sheds light on the research of buckyball-filled CNTs for other applications.

  5. A blind Green Bank Telescope millimetre-wave survey for redshifted molecular absorption

    CERN Document Server

    Kanekar, N; Carilli, C L; Stocke, J T; Willett, K W

    2013-01-01

    We present the methodology for ``blind'' millimetre-wave surveys for redshifted molecular absorption in the CO/HCO$^+$ rotational lines. The frequency range $30-50$ GHz appears optimal for such surveys, providing sensitivity to absorbers at $z \\gtrsim 0.85$. It is critical that the survey is ``blind'', i.e. based on a radio-selected sample, including sources without known redshifts. We also report results from the first large survey of this kind, using the Q-band receiver on the Green Bank Telescope (GBT) to search for molecular absorption towards 36 sources, 3 without known redshifts, over the frequency range $39.6 - 49.5$ GHz. The GBT survey has a total redshift path of $\\Delta z \\approx 24$, mostly at $0.81 < z < 1.91$, and a sensitivity sufficient to detect equivalent ${\\rm H_2}$ column densities $\\gtrsim 3 \\times 10^{21}$ cm$^{-2}$ in absorption at $5\\sigma$ significance (using the CO-to-${\\rm H_2}$ and HCO$^+$-to-${\\rm H_2}$ conversion factors of the Milky Way). The survey yielded no confirmed det...

  6. On the absence of molecular absorption in high redshift millimetre-band searches

    CERN Document Server

    Curran, S J; Combes, F; Kuno, N; Francis, P; Nakai, N; Webb, J K; Murphy, M T; Wiklind, T

    2011-01-01

    We have undertaken a search for millimetre-wave band absorption (through the CO and HCO+ rotational transitions) in the host galaxies of reddened radio sources (z = 0.405-1.802). Despite the colour selection (optical-near infrared colours of V - K > 5 in all but one source), no absorption was found in any of the eight quasars for which the background continuum flux was detected. On the basis of the previous (mostly intervening) H2 and OH detections, the limits reached here and in some previous surveys should be deep enough to detect molecular absorption according to their V - K colours. However, our survey makes the assumption that the reddening is associated with dust close to the emission redshift of the quasar and that the narrow millimetre component of this emission is intercepted by the compact molecular cores. By using the known millimetre absorbers to define the colour depth and comparing this with the ultra-violet luminosities of the sources, we find that, even if these assumptions are valid, only twe...

  7. A reduced density-matrix theory of absorption line shape of molecular aggregate.

    Science.gov (United States)

    Yang, Mino

    2005-09-22

    A theory for the absorption line shape of molecular aggregates in condensed phase is formulated based on a reduced density-matrix approach. Intermolecular couplings in the aggregates are assumed to be weak (Förster type of energy transfer mechanism). The spin-Boson model is employed to include the effect of electron-phonon coupling. Using the projection operator technique, we derive kinetic equations for the reduced electronic density matrix associated with the absorption spectrum. General expressions of time-dependent rate constants in the kinetic equations are derived by using the cumulant expansion technique. The resulting time-dependent kinetic equations are solved numerically. We illustrate the applicability of the present theory by calculating the line shape of a dimer (a pair of donor and acceptor of energy transfer). For a J-aggregate type of molecular pair (with excitonic redshift), a tail appears on the blue side of the absorption spectrum due to the existence of inhomogeneity in electronic state mixing which is originated from the electron-phonon coupling.

  8. Molecular Dynamics Investigation of Efficient SO₂ Absorption by Anion-Functionalized Ionic Liquids

    Indian Academy of Sciences (India)

    ANIRBAN MONDAL; SUNDARAM BALASUBRAMANIAN

    2017-07-01

    Ionic liquids are appropriate candidates for the absorption of acid gases such as SO₂. Six anion functionalized ionic liquids with different basicities have been studied for SO₂ absorption capacity by employing quantum chemical calculations and molecular dynamics (MD) simulations. Gas phase quantum calculations unveil that the high uptake of SO₂ in these ionic liquids originates from the basicity of the anions and the consequent enhanced anion-SO₂ interactions. MD simulations of SO₂–IL mixtures reveal the crucial role of both cations and anions in SO₂ dissolution. Multiple-site interactions of SO₂ with the anions have been identified. The calculated solvation free energy substantiates these observations. The order of computed Henry’s law constant values with change in the anion is in fair agreement with experimentally determined SO₂ solubility order.

  9. Randic and Schultz molecular topological indices and their correlation with some X-ray absorption parameters

    Science.gov (United States)

    Khatri, Sunil; Kekre, Pravin A.; Mishra, Ashutosh

    2016-10-01

    The properties of a molecular system are affected by the topology of molecule. Therefore many studies have been made where the various physic-chemical properties are correlated with the topological indices. These studies have shown a very good correlation demonstrating the utility of the graph theoretical approach. It is, therefore, very natural to expect that the various physical properties obtained by the X-ray absorption spectra may also show correlation with the topological indices. Some complexes were used to establish correlation between topological indices and some X-ray absorption parameters like chemical shift. The chemical shift is on the higher energy side of the metal edge in these complexes. The result obtained in these studies shows that the topological indices of organic molecule acting as a legands can be used for estimating edge shift theoretically.

  10. Determination of phosphorus using high-resolution diphosphorus molecular absorption spectra produced in the graphite furnace

    Science.gov (United States)

    Huang, Mao Dong; Becker-Ross, Helmut; Okruss, Michael; Geisler, Sebastian; Florek, Stefan

    2016-01-01

    Molecular absorption of diphosphorus was produced in a graphite furnace and evaluated in view of its suitability for phosphorus determination. Measurements were performed with two different high-resolution continuum source absorption spectrometers. The first system is a newly in-house developed simultaneous broad-range spectrograph, which was mainly used for recording overview absorption spectra of P2 between 193 nm and 245 nm. The region covers the main part of the C 1Σu+ ← X 1Σg+ electronic transition and shows a complex structure with many vibrational bands, each consisting of a multitude of sharp rotational lines. With the help of molecular data available for P2, an assignment of the vibrational bands was possible and the rotational structure could be compared with simulated spectra. The second system is a commercial sequential continuum source spectrometer, which was used for the basic analytical measurements. The P2 rotational line at 204.205 nm was selected and systematically evaluated with regard to phosphorus determination. The conditions for P2 generation were optimized and it was found that the combination of a ZrC modified graphite tube and borate as a chemical modifier were essential for a good production of P2. Serious interferences were found in the case of nitrate and sulfuric acid, although the nitrate interference can be eliminated by a higher pyrolysis temperature. The reliability of the method was proved by analysis of certified samples. Using standard tubes, a characteristic mass of 10 ng and a limit of detection of 7 ng were found. The values could further be improved by a factor of ten using a miniaturized tube with an internal diameter of 2 mm. Compared to the conventional method based on the phosphorus absorption line at 213.618 nm, the advantages of using P2 are the gentle temperature conditions and the potential of performing a simultaneous multi-line evaluation to further improve the limit of detection.

  11. Multi-filter spectrophotometry simulations

    Science.gov (United States)

    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.

  12. Kinetic and Diagnostic Studies of Molecular Plasmas Using Laser Absorption Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Welzel, S [INP-Greifswald, 17489 Greifswald, Felix-Hausdorff-Str. 2 (Germany); Rousseau, A [Laboratoire de Physique et Technologie des Plasmas, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Davies, P B [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Roepcke, J [INP-Greifswald, 17489 Greifswald, Felix-Hausdorff-Str. 2 (Germany)

    2007-10-15

    Within the last decade mid infrared absorption spectroscopy between 3 and 20 {mu}m, known as Infrared Laser Absorption Spectroscopy (IRLAS) and based on tuneable semiconductor lasers, namely lead salt diode lasers, often called tuneable diode lasers (TDL), and quantum cascade lasers (QCL) has progressed considerably as a powerful diagnostic technique for in situ studies of the fundamental physics and chemistry of molecular plasmas. The increasing interest in processing plasmas containing hydrocarbons, fluorocarbons, organo-silicon and boron compounds has lead to further applications of IRLAS because most of these compounds and their decomposition products are infrared active. IRLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which is of particular importance for the investigation of reaction kinetics. Information about gas temperature and population densities can also be derived from IRLAS measurements. A variety of free radicals and molecular ions have been detected, especially using TDLs. Since plasmas with molecular feed gases are used in many applications such as thin film deposition, semiconductor processing, surface activation and cleaning, and materials and waste treatment, this has stimulated the adaptation of infrared spectroscopic techniques to industrial requirements. The recent development of QCLs offers an attractive new option for the monitoring and control of industrial plasma processes as well as for highly time-resolved studies on the kinetics of plasma processes. The aim of the present article is threefold: (i) to review recent achievements in our understanding of molecular phenomena in plasmas (ii) to report on selected studies of the spectroscopic properties and kinetic behaviour of radicals, and (iii) to describe the current status of advanced instrumentation for TDLAS in the mid infrared.

  13. Engineered absorption enhancement and induced transparency in coupled molecular and plasmonic resonator systems.

    Science.gov (United States)

    Adato, Ronen; Artar, Alp; Erramilli, Shyamsunder; Altug, Hatice

    2013-06-12

    Coupled plasmonic resonators have become the subject of significant research interest in recent years as they provide a route to dramatically enhanced light-matter interactions. Often, the design of these coupled mode systems draws intuition and inspiration from analogies to atomic and molecular physics systems. In particular, they have been shown to mimic quantum interference effects, such as electromagnetically induced transparency (EIT) and Fano resonances. This analogy also been used to describe the surface-enhanced absorption effect where a plasmonic resonance is coupled to a weak molecular resonance. These important phenomena are typically described using simple driven harmonic (or linear) oscillators (i.e., mass-on-a-spring) coupled to each other. In this work, we demonstrate the importance of an essential interdependence between the rate at which the system can be driven by an external field and its damping rate through radiative loss. This link is required in systems exhibiting time-reversal symmetry and energy conservation. Not only does it ensure an accurate and physically consistent description of resonant systems but leads directly to interesting new effects. Significantly, we demonstrate this dependence to predict a transition between EIT and electromagnetically induced absorption that is solely a function of the ratio of the radiative to intrinsic loss rates in coupled resonator systems. Leveraging the temporal coupled mode theory, we introduce a unique and intuitive picture that accurately describes these effects in coupled plasmonic/molecular and fully plasmonic systems. We demonstrate our approach's key features and advantages analytically as well as experimentally through surface-enhanced absorption spectroscopy and plasmonic metamaterial applications.

  14. Solid phase microextraction of diclofenac using molecularly imprinted polymer sorbent in hollow fiber combined with fiber optic-linear array spectrophotometry.

    Science.gov (United States)

    Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh; Khodadoust, Saeid

    2015-08-05

    A simple solid phase microextraction method based on molecularly imprinted polymer sorbent in the hollow fiber (MIP-HF-SPME) combined with fiber optic-linear array spectrophotometer has been applied for the extraction and determination of diclofenac in environmental and biological samples. The effects of different parameters such as pH, times of extraction, type and volume of the organic solvent, stirring rate and donor phase volume on the extraction efficiency of the diclofenac were investigated and optimized. Under the optimal conditions, the calibration graph was linear (r(2)=0.998) in the range of 3.0-85.0 μg L(-1) with a detection limit of 0.7 μg L(-1) for preconcentration of 25.0 mL of the sample and the relative standard deviation (n=6) less than 5%. This method was applied successfully for the extraction and determination of diclofenac in different matrices (water, urine and plasma) and accuracy was examined through the recovery experiments.

  15. Solid phase microextraction of diclofenac using molecularly imprinted polymer sorbent in hollow fiber combined with fiber optic-linear array spectrophotometry

    Science.gov (United States)

    Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh; Khodadoust, Saeid

    2015-08-01

    A simple solid phase microextraction method based on molecularly imprinted polymer sorbent in the hollow fiber (MIP-HF-SPME) combined with fiber optic-linear array spectrophotometer has been applied for the extraction and determination of diclofenac in environmental and biological samples. The effects of different parameters such as pH, times of extraction, type and volume of the organic solvent, stirring rate and donor phase volume on the extraction efficiency of the diclofenac were investigated and optimized. Under the optimal conditions, the calibration graph was linear (r2 = 0.998) in the range of 3.0-85.0 μg L-1 with a detection limit of 0.7 μg L-1 for preconcentration of 25.0 mL of the sample and the relative standard deviation (n = 6) less than 5%. This method was applied successfully for the extraction and determination of diclofenac in different matrices (water, urine and plasma) and accuracy was examined through the recovery experiments.

  16. Absorption Coefficient, Molecular Composition, and Photodegradation of Different Types of Brown Carbon Aerosols

    Science.gov (United States)

    Lee, H. J.; Aiona, P. K.; Nizkorodov, S.; Laskin, J.; Laskin, A.

    2014-12-01

    Atmospheric aerosols that absorb solar radiation have a direct effect on climate. Brown carbon (BrC) represents the type of carbonaceous aerosols characterized by large absorption coefficients in the near-UV range of the spectrum. BrC can be either directly emitted into the atmosphere from combustion sources, or be formed in the atmosphere through multi-phase reactions, such as aging of secondary organic aerosols (SOA) mediated by ammonium sulfate (AS). Under the conditions of exposure to solar radiation, both primary and secondary BrC can potentially change their molecular composition and optical properties as a result of photodegradation of chromophoric compounds. This presentation will discuss the molecular level composition, the absorption and fluorescence spectra, and the mechanism of photodegradation among several representative types of BrC. The primary BrC samples include aerosol produced by smoldering wood combustion. The secondary BrC samples include AS aged products of chamber-generated SOA, products of reaction between methylglyoxal and AS, and SOA produced by the hogh-NOx photooxdiation of aromatic compounds, such as naphthalene. This presentation will also include preliminary data on the absorption and fluorescence spectra of photo-degraded bioaerosols. In all cases, absorption spectra of extracted bulk samples are measured during irradiation by a known flux of UV or visible light. The molecular level composition of the fresh and photobleached samples are characterized by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). Photobleaching of BrC is found to occur over a range of atmospherically relevant time scales. In many cases, the molecular level composition of photobleached BrC exhibits only subtle changes suggesting that the optical and fluorescence properties of BrC are controlled by a few compounds present in low quantities. The observed fluorescence from non-biological BrC indicates potential issues in using fluorescence

  17. X-ray absorption Debye-Waller factors from ab initio molecular dynamics

    Science.gov (United States)

    Vila, F. D.; Lindahl, V. E.; Rehr, J. J.

    2012-01-01

    An ab initio equation of motion method is introduced to calculate the temperature-dependent mean-square vibrational amplitudes σ2 which appear in the Debye-Waller factors in x-ray absorption, x-ray scattering, and related spectra. The approach avoids explicit calculations of phonon modes, and is based instead on calculations of the displacement-displacement time correlation function from ab initio density functional theory molecular dynamics simulations. The method also yields the vibrational density of states and thermal quantities such as the lattice free energy. Illustrations of the method are presented for a number of systems and compared with other methods and experiment.

  18. Multi-wavelength spectrophotometry of EX Hydrae

    CERN Document Server

    Eisenbart, S; Reinsch, K; Gänsicke, B T

    2002-01-01

    We present phase-resolved infrared and optical spectrophotometry of the intermediate polar EX Hya supplemented by archival ultraviolet data. The spin-modulated emission from the accretion funnel and the emission from the accretion disk or ring contain substantial optically thin components. The white dwarf dominates the unmodulated flux in the ultraviolet and is identified by numerous absorption lines. Metal absorption in the accretion curtain may add to the observed spectral features. The secondary star is of spectral type M4+-1 and is detected by its ellipsoidal modulation. We derive a distance of 65+-11 pc which makes EX Hydrae one of the closest cataclysmic variables with a known distance. The luminosity derived from the integrated overall spectral energy distribution is 3x10^32 erg/s. The accretion rate of 3x10^15 g/s (for an 0.6 Msun white dwarf) is in reasonable agreement with the rates expected from angular momentum loss by gravitational radiation and from the observed spin-up of the white dwarf

  19. Comparison of path integral molecular dynamics methods for the infrared absorption spectrum of liquid water

    Science.gov (United States)

    Habershon, Scott; Fanourgakis, George S.; Manolopoulos, David E.

    2008-08-01

    The ring polymer molecular dynamics (RPMD) and partially adiabatic centroid molecular dynamics (PA-CMD) methods are compared and contrasted in an application to the infrared absorption spectrum of a recently parametrized flexible, polarizable, Thole-type potential energy model for liquid water. Both methods predict very similar spectra in the low-frequency librational and intramolecular bending region at wavenumbers below 2500 cm-1. However, the RPMD spectrum is contaminated in the high-frequency O-H stretching region by contributions from the internal vibrational modes of the ring polymer. This problem is avoided in the PA-CMD method, which adjusts the elements of the Parrinello-Rahman mass matrix so as to shift the frequencies of these vibrational modes beyond the spectral range of interest. PA-CMD does not require any more computational effort than RPMD and it is clearly the better of the two methods for simulating vibrational spectra.

  20. Molecular clusters size of Puerariae thomsonii radix aqueous decoction and relevance to oral absorption.

    Science.gov (United States)

    Wang, Gong; Yang, Caimei; Zhang, Kuan; Hu, Juan; Pang, Wensheng

    2015-07-07

    The multi-component system of traditional Chinese medicine (TCM) is very complicated. The clusters are dynamic aggregates whose molecules are held together by hydrogen-bonded, Van der Waals forces or the opposite charges of particles attract each other. In this paper, field emission scanning electron microscopy proved that molecules form clusters in Pueraria thomsonii Benth (Fenge) water decoction. Four kinds of Fenge water decoction, 0.07 g∙mL-1 (F-1), 0.1 g∙mL-1 (F-2), 0.17 g∙mL-1 (F-3), 0.35 g∙mL-1 (F-4); F-1, average diameter of molecular was about 120 nm; F-2, 195 nm; F-3, 256 nm; and F-4, 480 nm. The molecular size was shown to depend on concentration. Rabbits were given equal does of 2.8 g∙kg-1, to perfuse F-1, F-2, F-3, F-4 in volume of 80 mL, 56 mL, 33 mL, 17 mL, respectively. At 0-180 min to collect 2 mL blood from the rabbit ears middle arteries for metabolism fingerprints, the results show the particle size of molecular is smaller, the absorption of drugs is better instead. The acute blood stasis model rats were treatment with Fenge decoction of 1.5 g∙kg-1 for 14 days, the concentrations of Ang II in plasma were significantly lower in F-1 and F-2 groups than those in model group (p 0.05). Despite the molecular aggregation is a common physical phenomenon, it influence on the kind and amount of molecule per unit volume. Molecules morphology influence on the absorption behavior of drugs in vivo therefore is to have an impact on pharmacological function.

  1. Determination of sulfur in food by high resolution continuum source flame molecular absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zambrzycka, Elżbieta; Godlewska-Żyłkiewicz, Beata, E-mail: bgodlew@uwb.edu.pl

    2014-11-01

    In the present work, a fast, simple and sensitive analytical method for determination of sulfur in food and beverages by high resolution continuum source flame molecular absorption spectrometry was developed. The determination was performed via molecular absorption of carbon monosulfide, CS. Different CS rotational lines (257.959 nm, 258.033 nm, 258.055 nm), number of pixels and types of standard solution of sulfur, namely: sulfuric acid, sodium sulfate, ammonium sulfate, sodium sulfite, sodium sulfide, DL-cysteine, and L-cystine, were studied in terms of sensitivity, repeatability of results as well as limit of detection and limit of quantification. The best results were obtained for measurements of absorption of the CS molecule at 258.055 nm at the wavelength range covering 3 pixels and DL-cysteine in 0.2 mol L{sup −1} HNO{sub 3} solution as a calibration standard. Under optimized conditions the limit of detection and the limit of quantification achieved for sulfur were 10.9 mg L{sup −1} and 36.4 mg L{sup −1}, respectively. The repeatability of the results expressed as relative standard deviation was typically < 5%. The accuracy of the method was tested by analysis of digested biological certified reference materials (soya bean flour, corn flour and herbs) and recovery experiment for beverage samples with added known amount of sulfur standard. The recovery of analyte from such samples was in the range of 93–105% with the repeatability in the range of 4.1–5.0%. The developed method was applied for the determination of sulfur in milk (194 ± 10 mg kg{sup −1}), egg white (2188 ± 29 mg kg{sup −1}), mineral water (31.0 ± 0.9 mg L{sup −1}), white wine (260 ± 4 mg L{sup −1}) and red wine (82 ± 2 mg L{sup −1}), as well as in sample rich in ions, such as bitter mineral water (6900 ± 100 mg L{sup −1}). - Highlights: • HR-CS FMAS technique was used for sulfur measurement via molecular absorption of carbon monosulfide, CS. • Organic DL

  2. Molecular Hydrogen Absorption from the Halo of a z~0.4 Galaxy

    CERN Document Server

    Muzahid, Sowgat; Charlton, Jane C; Churchill, Christopher W

    2016-01-01

    Lyman- and Werner-band absorption of molecular hydrogen (H2) is detected in ~50% of low redshift (z10^14.4 cm^-2. However the true origin(s) of the H2 bearing gas remain elusive. Here we report a new detection of an H2 absorber at z = 0.4298 in the HST/COS spectra of quasar PKS~2128--123. The total N(HI) of 10^{19.50\\pm0.15} cm^-2 classifies the absorber as a sub-DLA. H2 absorption is detected up to the J=3 rotational level with a total log N(H2)=16.36\\pm0.08 corresponding to a molecular fraction of log f(H2)=-2.84\\pm0.17. The excitation temperature of T_ex = 206\\pm6K indicates the presence of cold gas. Using detailed ionization modelling we obtain a near-solar metallicity (i.e., [O/H]= -0.26\\pm0.19) and a dust-to-gas ratio of log \\kappa ~ -0.45 for the H2 absorbing gas. The host-galaxy of the sub-DLA is detected at an impact parameter of \\rho ~ 48 kpc with an inclination angle of i~48 degree and an azimuthal angle of \\Phi ~ 15 degree with respect to the QSO sightline. We show that co-rotating gas in an exten...

  3. 金属滤筒吸收-红外分光光度法测定淬火油烟的浓度%Determination of Quenching Oil Fumes Concentration by Metal Filter Cylinder-Absorption and Infrared Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    衡兆祥

    2014-01-01

    Quenching oil fume in the heat treatment process was collected with automatic tracking method. Fiter which collected oil fumes was placed in teflon sleeve with lid. Ultrasonic cleaning was carried out in lab, cleaning liquid was moved in the volumetric flask, then oil content was determined by infrared spectrophotometry. In the range of 0.0-100 mg/L, standard oil concentration detection value was linear with standard value, the correlation coefficient r=0.999 6. The recovery was 85.9%-106.2%, the relative standard deviation was 1.05%-1.92%(n=6), and the detection limit was 0.25 mg/m3. The method is sensitive and accurate, it can be used for testing the effect of enterprises oil fume control, and environmental protection department supervision and monitoring in enterprises fume emission concentration.%用自动跟踪法采集热处理工艺中淬火油烟,将收集油烟的滤芯置于带盖的聚四氟乙烯套筒,用四氯化碳作溶剂进行超声清洗,清洗液移入容量瓶中定容,用红外分光光度法测定油烟含量。在0.0~100 mg/L范围内,标准淬火油质量浓度实测值与与标准值呈良好的线性,相关系数r=0.9996。加标回收率为85.9%~106.2%,相对标准偏差为1.05%~1.92%(n=6),检出限为0.25 mg/m3。该方法灵敏度高,测定结果准确,可用于企业油烟治理效果的验收检测及环保部门对企业淬火油烟排放浓度的监督监测。

  4. Formaldehyde in Absorption: Tracing Molecular Gas in Early-Type Galaxies

    Science.gov (United States)

    Dollhopf, Niklaus M.; Donovan Meyer, Jennifer

    2016-01-01

    Early-Type Galaxies (ETGs) have been long-classified as the red, ellipsoidal branch of the classic Hubble tuning fork diagram of galactic structure. In part with this classification, ETGs are thought to be molecular and atomic gas-poor with little to no recent star formation. However, recent efforts have questioned this ingrained classification. Most notably, the ATLAS3D survey of 260 ETGs within ~40 Mpc found 22% contain CO, a common tracer for molecular gas. The presence of cold molecular gas also implies the possibility for current star formation within these galaxies. Simulations do not accurately predict the recent observations and further studies are necessary to understand the mechanisms of ETGs.CO traces molecular gas starting at densities of ~102 cm-3, which makes it a good tracer of bulk molecular gas, but does little to constrain the possible locations of star formation within the cores of dense molecular gas clouds. Formaldehyde (H2CO) traces molecular gas on the order of ~104 cm-3, providing a further constraint on the location of star-forming gas, while being simple enough to possibly be abundant in gas-poor ETGs. In cold molecular clouds at or above ~104 cm-3 densities, the structure of formaldehyde enables a phenomenon in which rotational transitions have excitation temperatures driven below the temperature of the cosmic microwave background (CMB), ~2.7 K. Because the CMB radiates isotropically, formaldehyde can be observed in absorption, independent of distance, as a tracer of moderately-dense molecular clouds and star formation.This novel observation technique of formaldehyde was incorporated for observations of twelve CO-detected ETGs from the ATLAS3D sample, including NGC 4710 and PGC 8815, to investigate the presence of cold molecular gas, and possible star formation, in ETGs. We present images from the Very Large Array, used in its C-array configuration, of the J = 11,0 - 11,1 transition of formaldehyde towards these sources. We report our

  5. 利用土壤干燥箱主动干燥-微波消解-原子吸收分光光度法测定土壤中的重金属%Determination of Heavy Metal in Soil through Active Drying of Soil Drying Oven,Microwave Digestion and Atomic Absorption Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    张健美; 吴春妍; 许卫娟

    2012-01-01

    The heavy metal in a large amount of soil sample could be determined in a short time by drying the soil with M280685 soil drying oven,microwave digestion and atomic absorption spectrophotometry.The qualified rate of the parallel double-sample testing by this method and the quality-controlled samples can both reach the requirements of Technical Specification for Soil Environmental Monitoring(HJ/T166-2004).%利用M280685土壤干燥箱干燥土壤、微波消解、原子吸收分光光度法,在短时间内完成大量土壤样品中重金属的测定。利用该法测定土壤中的重金属平行双样测定合格率,质控样品均能达到土壤环境监测技术规范(HJ/T166-2004)相应的要求。

  6. Capturing a photoexcited molecular structure through time-domain x-ray absorption fine structure.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L. X.; Jaeger, W. J. H.; Jennings, G.; Gosztola, D. J.; Munkholm, A.; Hessler, J. P.

    2001-04-13

    The determination of the structure of transient molecules, such as photoexcited states, in disordered media (such as in solution) usually requires methods with high temporal resolution. The transient molecular structure of a reaction intermediate produced by photoexcitation of NiTPP-L{sub 2} (NiTPP, nickeltetraphenylporphyrin; L, piperidine) in solution was determined by x-ray absorption fine structure (XAFS) data obtained on a 14-nanosecond time scale from a third-generation synchrotron source. The XAFS measurements confirm that photoexcitation leads to the rapid removal of both axial ligands to produce a transient square-planar intermediate, NiTPP, with a lifetime of 28 nanoseconds. The transient structure of the photodissociated intermediate is nearly identical to that of the ground state NiTPP, suggesting that the intermediate adopts the same structure as the ground state in a noncoordinating solvent before it recombines with two ligands to form the more stable octahedrally coordinated NiTPP-L{sub 2}.

  7. kspectrum: an open-source code for high-resolution molecular absorption spectra production

    Science.gov (United States)

    Eymet, V.; Coustet, C.; Piaud, B.

    2016-01-01

    We present the kspectrum, scientific code that produces high-resolution synthetic absorption spectra from public molecular transition parameters databases. This code was originally required by the atmospheric and astrophysics communities, and its evolution is now driven by new scientific projects among the user community. Since it was designed without any optimization that would be specific to any particular application field, its use could also be extended to other domains. kspectrum produces spectral data that can subsequently be used either for high-resolution radiative transfer simulations, or for producing statistic spectral model parameters using additional tools. This is a open project that aims at providing an up-to-date tool that takes advantage of modern computational hardware and recent parallelization libraries. It is currently provided by Méso-Star (http://www.meso-star.com) under the CeCILL license, and benefits from regular updates and improvements.

  8. Isotopic ratios at z=0.68 from molecular absorption lines toward B 0218+357

    CERN Document Server

    Wallstrom, S H J; Guelin, M

    2016-01-01

    Isotopic ratios of heavy elements are a key signature of the nucleosynthesis processes in stellar interiors. The contribution of successive generations of stars to the metal enrichment of the Universe is imprinted on the evolution of isotopic ratios over time. We investigate the isotopic ratios of carbon, nitrogen, oxygen, and sulfur through millimeter molecular absorption lines arising in the z=0.68 absorber toward the blazar B 0218+357. We find that these ratios differ from those observed in the Galactic interstellar medium, but are remarkably close to those in the only other source at intermediate redshift for which isotopic ratios have been measured to date, the z=0.89 absorber in front of PKS1830-211. The isotopic ratios in these two absorbers should reflect enrichment mostly from massive stars, and they are indeed close to the values observed toward local starburst galaxies. Our measurements set constraints on nucleosynthesis and chemical evolution models.

  9. Anharmonic resonance absorption of short laser pulses in clusters: A molecular dynamics simulation study

    Science.gov (United States)

    Mahalik, S. S.; Kundu, M.

    2016-12-01

    Linear resonance (LR) absorption of an intense 800 nm laser light in a nano-cluster requires a long laser pulse >100 fs when Mie-plasma frequency ( ω M ) of electrons in the expanding cluster matches the laser frequency (ω). For a short duration of the pulse, the condition for LR is not satisfied. In this case, it was shown by a model and particle-in-cell (PIC) simulations [Phys. Rev. Lett. 96, 123401 (2006)] that electrons absorb laser energy by anharmonic resonance (AHR) when the position-dependent frequency Ω [ r ( t ) ] of an electron in the self-consistent anharmonic potential of the cluster satisfies Ω [ r ( t ) ] = ω . However, AHR remains to be a debate and still obscure in multi-particle plasma simulations. Here, we identify AHR mechanism in a laser driven cluster using molecular dynamics (MD) simulations. By analyzing the trajectory of each MD electron and extracting its Ω [ r ( t ) ] in the self-generated anharmonic plasma potential, it is found that electron is outer ionized only when AHR is met. An anharmonic oscillator model, introduced here, brings out most of the features of MD electrons while passing the AHR. Thus, we not only bridge the gap between PIC simulations, analytical models, and MD calculations for the first time but also unequivocally prove that AHR process is a universal dominant collisionless mechanism of absorption in the short pulse regime or in the early time of longer pulses in clusters.

  10. NARROW Na AND K ABSORPTION LINES TOWARD T TAURI STARS: TRACING THE ATOMIC ENVELOPE OF MOLECULAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Pascucci, I.; Simon, M. N. [Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Edwards, S. [Five College Astronomy Department, Smith College, Northampton, MA 01063 (United States); Heyer, M. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003-9305 (United States); Rigliaco, E. [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Hillenbrand, L. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Gorti, U.; Hollenbach, D., E-mail: pascucci@lpl.arizona.edu [SETI Institute, Mountain View, CA 94043 (United States)

    2015-11-20

    We present a detailed analysis of narrow Na i and K i absorption resonance lines toward nearly 40 T Tauri stars in Taurus with the goal of clarifying their origin. The Na i λ5889.95 line is detected toward all but one source, while the weaker K i λ7698.96 line is detected in about two-thirds of the sample. The similarity in their peak centroids and the significant positive correlation between their equivalent widths demonstrate that these transitions trace the same atomic gas. The absorption lines are present toward both disk and diskless young stellar objects, which excludes cold gas within the circumstellar disk as the absorbing material. A comparison of Na i and CO detections and peak centroids demonstrates that the atomic gas and molecular gas are not co-located, the atomic gas being more extended than the molecular gas. The width of the atomic lines corroborates this finding and points to atomic gas about an order of magnitude warmer than the molecular gas. The distribution of Na i radial velocities shows a clear spatial gradient along the length of the Taurus molecular cloud filaments. This suggests that absorption is associated with the Taurus molecular cloud. Assuming that the gradient is due to cloud rotation, the rotation of the atomic gas is consistent with differential galactic rotation, whereas the rotation of the molecular gas, although with the same rotation axis, is retrograde. Our analysis shows that narrow Na i and K i absorption resonance lines are useful tracers of the atomic envelope of molecular clouds. In line with recent findings from giant molecular clouds, our results demonstrate that the velocity fields of the atomic and molecular gas are misaligned. The angular momentum of a molecular cloud is not simply inherited from the rotating Galactic disk from which it formed but may be redistributed by cloud–cloud interactions.

  11. Molecular Clusters Size of Puerariae thomsonii Radix Aqueous Decoction and Relevance to Oral Absorption

    Directory of Open Access Journals (Sweden)

    Gong Wang

    2015-07-01

    Full Text Available The multi-component system of traditional Chinese medicine (TCM is very complicated. The clusters are dynamic aggregates whose molecules are held together by hydrogen-bonded, Van der Waals forces or the opposite charges of particles attract each other. In this paper, field emission scanning electron microscopy proved that molecules form clusters in Pueraria thomsonii Benth (Fenge water decoction. Four kinds of Fenge water decoction, 0.07 g∙mL−1 (F-1, 0.1 g∙mL−1 (F-2, 0.17 g∙mL−1 (F-3, 0.35 g∙mL−1 (F-4; F-1, average diameter of molecular was about 120 nm; F-2, 195 nm; F-3, 256 nm; and F-4, 480 nm. The molecular size was shown to depend on concentration. Rabbits were given equal does of 2.8 g∙kg−1, to perfuse F-1, F-2, F-3, F-4 in volume of 80 mL, 56 mL, 33 mL, 17 mL, respectively. At 0–180 min to collect 2 mL blood from the rabbit ears middle arteries for metabolism fingerprints, the results show the particle size of molecular is smaller, the absorption of drugs is better instead. The acute blood stasis model rats were treatment with Fenge decoction of 1.5 g∙kg−1 for 14 days, the concentrations of Ang II in plasma were significantly lower in F-1 and F-2 groups than those in model group (p < 0.01 or p < 0.05, but there were no significantly difference in F-3 and F-4 groups than those in model group (p > 0.05. Despite the molecular aggregation is a common physical phenomenon, it influence on the kind and amount of molecule per unit volume. Molecules morphology influence on the absorption behavior of drugs in vivo therefore is to have an impact on pharmacological function.

  12. Atomic Oxygen Abundance in Molecular Clouds: Absorption Toward Sagittarius B2

    Science.gov (United States)

    Lis, D. C.; Keene, Jocelyn; Phillips, T. G.; Schilke, P.; Werner, M. W.; Zmuidzinas, J.

    2001-01-01

    We have obtained high-resolution (approximately 35 km/s) spectra toward the molecular cloud Sgr B2 at 63 micrometers, the wavelength of the ground-state fine-structure line of atomic oxygen (O(I)), using the ISO-LWS instrument. Four separate velocity components are seen in the deconvolved spectrum, in absorption against the dust continuum emission of Sgr B2. Three of these components, corresponding to foreground clouds, are used to study the O(I) content of the cool molecular gas along the line of sight. In principle, the atomic oxygen that produces a particular velocity component could exist in any, or all, of three physically distinct regions: inside a dense molecular cloud, in the UV illuminated surface layer (PDR) of a cloud, and in an atomic (H(I)) gas halo. For each of the three foreground clouds, we estimate, and subtract from the observed O(I) column density, the oxygen content of the H(I) halo gas, by scaling from a published high-resolution 21 cm spectrum. We find that the remaining O(I) column density is correlated with the observed (13)CO column density. From the slope of this correlation, an average [O(I)]/[(13)CO] ratio of 270 +/- 120 (3-sigma) is derived, which corresponds to [O(I)]/[(13)CO] = 9 for a CO to (13)CO abundance ratio of 30. Assuming a (13)CO abundance of 1x10(exp -6) with respect to H nuclei, we derive an atomic oxygen abundance of 2.7x10(exp -4) in the dense gas phase, corresponding to a 15% oxygen depletion compared to the diffuse ISM in our Galactic neighborhood. The presence of multiple, spectrally resolved velocity components in the Sgr B2 absorption spectrum allows, for the first time, a direct determination of the PDR contribution to the O(I) column density. The PDR regions should contain O(I) but not (13)CO, and would thus be expected to produce an offset in the O(I)-(13)CO correlation. Our data do not show such an offset, suggesting that within our beam O(I) is spatially coexistent with the molecular gas, as traced by (13)CO

  13. Determination of Mercury in Air by Gold Film Adsorption-Cold Atomic Absorption Spectrophotometry%金膜吸附-冷原子吸收光谱法测定空气中的汞

    Institute of Scientific and Technical Information of China (English)

    范慧群

    2013-01-01

    The new type of gold film adsorption-cold atomic absorption spectrophotometric method was a-dopted to determine mercury in air .Good linearity was obtained within the concentration scope of 0 μg/L~100 μg/L, with the correlation coefficient 0.999 1.The detection limit come to be 1.6 ng/m3 , with the RSDs ranged from 0.5%to 2.7%.Relative errors were 6.1%and 3.2% respectively when two different concentra-tions of mercury standard samples were determined by the current method .Compared this method and the two kinds of the current national standard method ( Enrichment of sulfhydryl cotton and potassium permanganate solu-tion absorption method ) , this method needs less kinds of agents and is easy to handle .Meanwhile , this method show high adsorption efficiency and high spiked recoveries .%采用新型金膜吸附-冷原子吸收光谱法测定空气中的汞,在0μg/L~100μg/L范围内线性良好,相关系数为0.9991。方法检出限为1.6 ng/m3,RSD为0.5%~2.7%,测定两种不同浓度的汞标准样品,相对误差为6.1%和3.2%。与两种现行国标方法(巯基棉富集和高锰酸钾溶液吸附法)比较,该方法所需试剂种类少,操作简便、吸附效率好,加标回收率高。

  14. 原子吸收光谱法测定桃儿七中微量金属元素含量%Determination of micronutrient in sinopodophyllum emodi by atomic absorption spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    温普红; 赵卫星; 王艳

    2011-01-01

    目的:应用原子吸收光谱法测定桃儿七中微量金属元素.方法:采用原子发射光谱法进行定性分析,原子吸收光谱法进行定量分析.结果:桃儿七中微量元素的含量为:钙449.1 mg/kg;镁48.5 mg/kg;锌55.3 mg/kg;铜195.1 mg/kg;锰16.8 mg/kg;铁188.6 mg/kg,RSD≤0.8%,加样回收率为97.9%~102.1%.结论:该方法准确度较高,简便易行,处理一次样品可连续测定多种元素.%Objective: To determine the micronutfient in sinopodophyllum emodi by atomic absorption sepctrophotometry.Methods: The qualitative determination was carried out by atomic emission spectrometry (AES) method.On the basis of the resuhs, atomic absorption spectrometry (AAS) method was developed to determine micronutrient in sinopodophyllum emodi.Results: The micronutrient of Ca, Mg, Zn, Ca, Mn and Fe in sinopodophyllum emodi was respectively 449.1, 48.5, 55.3,195.1, 16.8, 188.6 mg/kg in the sample with RSD ≤0.8%, and the recoveries were 97.9%-102.1%.Conclusion: This method is exact and handy, and can be used in sequential determination of multi-elements in one sample solution.

  15. Molecular Hydrogen Absorption from the Halo of a z ˜ 0.4 Galaxy

    Science.gov (United States)

    Muzahid, Sowgat; Kacprzak, Glenn G.; Charlton, Jane C.; Churchill, Christopher W.

    2016-05-01

    Lyman- and Werner-band absorption of molecular hydrogen ({{{H}}}2) is detected in ˜50% of low-redshift (z\\lt 1) DLAs/sub-DLAs with N({{{H}}}2) \\gt {10}14.4 cm-2. However, the true origin(s) of the {{{H}}}2-bearing gas remain elusive. Here we report a new detection of an {{{H}}}2 absorber at {z}{{abs}} = 0.4298 in the Hubble Space Telescope (HST)/Cosmic Origins Spectrograph spectra of quasar PKS 2128-123. The total N({{H}} {{i}}) of {10}19.50+/- 0.15 cm-2 classifies the absorber as a sub-DLA. {{{H}}}2 absorption is detected up to the J = 3 rotational level with a total {log}N({{{H}}}2) = 16.36 ± 0.08, corresponding to a molecular fraction of {log}{f}{{{H}}2} = -2.84 ± 0.17. The excitation temperature of {T}{{ex}} = 206 ± 6 K indicates the presence of cold gas. Using detailed ionization modeling, we obtain a near-solar metallicity (i.e., [O/H] = -0.26 ± 0.19) and a dust-to-gas ratio of {log}κ ˜ -0.45 for the {{{H}}}2-absorbing gas. The host galaxy of the sub-DLA is detected at an impact parameter of ρ ˜ 48 kpc with an inclination angle of i ˜ 48° and an azimuthal angle of Φ ˜ 15° with respect to the QSO sightline. We show that corotating gas in an extended disk cannot explain the observed kinematics of Mg ii absorption. Moreover, the inferred high metallicity is not consistent with the scenario of gas accretion. An outflow from the central region of the host galaxy, on the other hand, would require a large opening angle (i.e., 2θ \\gt 150^\\circ ), much larger than the observed outflow opening angles in Seyfert galaxies, in order to intercept the QSO sightline. We thus favor a scenario in which the {{{H}}}2-bearing gas is stemming from a dwarf-satellite galaxy, presumably via tidal and/or ram pressure stripping. Detection of a dwarf galaxy candidate in the HST/WFPC2 image at an impact parameter of ˜12 kpc reinforces such an idea.

  16. Plasmon enhanced molecular absorption: A mixed quantum–classical description of supramolecular complexes attached to a metal nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Megow, Jörg, E-mail: megow@physik.hu-berlin.de; May, Volkhard, E-mail: may@physik.hu-berlin.de

    2014-01-15

    Highlights: • Enhancement of molecular absorption was shown for J-aggregate-like coupling between molecules and MNP. • A large number of molecules is required in order to observe the molecular absorption. • Pheos Qx-band coupling to the plasmon resonance is hardly observable in the spectrum. - Abstract: The application of a mixed quantum–classical methodology for an investigation of single pheophorbide-a molecules (Pheos) and respective supramolecular complexes is continued to effects caused by a nearby placed metal nanoparticle (MNP). Therefore, the classical simulation of the molecular nuclear degrees of freedom is combined with a uniform quantum description of the molecular electronic excitations coupled to those of the MNP. To account for the short MNP plasmon life time the quantum dynamics of the electronic degrees of freedom is formulated in the framework of a system-bath theory. Linear absorption spectra are calculated for a spherical 14 nm diameter Au–MNP decorated with isolated Pheos or with P{sub 16} complexes formed by 16 Pheos. The spectra are analyzed with respect to the molecular orientation at the MNP surface. While all studies on P{sub 16} only account for the Pheo Q{sub y}-transition we also present data on the MNP induced change of the single Pheo Q{sub x}-absorption.

  17. A new approach for fluorine determination by solid sampling graphite furnace molecular absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lisandro de Moraes Flores, Eder [Universidade Federal de Santa Maria, Departamento de Quimica, 97105-900, Santa Maria, RS (Brazil); Universidade Estadual do Estado do Rio Grande do Sul, 97573-011, Santana do Livramento, RS (Brazil); Smanioto Barin, Juliano [Universidade Federal de Santa Maria, Departamento de Quimica, 97105-900, Santa Maria, RS (Brazil); Universidade Regional Integrada do Alto Uruguai, 98400-000, Frederico Westphalen, RS (Brazil); Moraes Flores, Erico Marlon de [Universidade Federal de Santa Maria, Departamento de Quimica, 97105-900, Santa Maria, RS (Brazil); Dressler, Valderi Luiz [Universidade Federal de Santa Maria, Departamento de Quimica, 97105-900, Santa Maria, RS (Brazil)], E-mail: valdres@quimica.ufsm.br

    2007-09-15

    This work deals with the determination of fluorine by solid sampling graphite furnace molecular absorption spectrometry. The molecular absorbance of aluminum monofluoride (AlF), which is produced in the vapor phase in the presence of Al{sup 3+}, is measured at 227.5 nm, a non-resonant platinum line. A conventional graphite furnace program has been used with pyrolysis and vaporization temperatures of 800 and 2300 deg. C, respectively. Solutions of Ba{sup 2+} and Al{sup 3+} have been used to avoid fluorine losses during the pyrolysis stage and to produce AlF in the vaporization stage, respectively. Certified coal and alumina samples were analyzed using aqueous standards for calibration. The agreement between the found concentration and the certified value, or the value obtained by another method ranged from 92 to 105%, with a relative standard deviation less than 8.5%. The limit of detection and the characteristic mass was 0.17 {mu}g g{sup -1} and 205 pg, respectively.

  18. Molecular characterization of brominated persistent pollutants using extended X-ray absorption fine structure (EXAFS) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bergknut, Magnus; Skyllberg, Ulf [Swedish University of Agricultural Sciences (SLU), Department of Forest Ecology and Management, Umeaa (Sweden); Persson, Per [Umeaa University, Department of Chemistry, Umeaa (Sweden)

    2008-02-15

    X-ray absorption fine structure (EXAFS) spectroscopy spectra were collected for three brominated persistent pollutants: 6-bromo-2,4,5-trichlorophenol (BrTriClP), pentabromophenol (PentaBrP) and 3,3',5,5'-tetrabromobisphenol A (TBBA). The substances were selected to be symmetrical (BrTriClP and TBBA) or asymmetrical (PentaBrP) with respect to the atomic Br positions and to differ in the number of bromine and other halide atoms, as well as their relative positions. The asymmetrical PentaBrP was modelled with special detail as not all bromine atoms have identical coordination environments. The studied substances displayed unique EXAFS spectra, which could be used to determine the molecular structure in fair detail. We conclude that EXAFS spectroscopy is a suitable technique for molecular characterization of the comparatively complex molecules within the class of compounds of brominated organic persistent pollutants. A detailed understanding of the EXAFS spectra of the pure compounds opens up possibilities to study the interactions with soil and sediment matrices by means of EXAFS spectroscopy. (orig.)

  19. 火焰原子吸收法测定硝酸钍中微量钾和钠%Determination of Potassium and Sodium in Thorium Nitrate by Flame Atomic Absorption Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    李晓红; 王春叶; 郭国龙

    2015-01-01

    The thorium nitrate was dissolved in water .In acidic medium ,eliminating the disturbance of ionization by adding cesium chloride ,potassium and sodium in the thorium nitrate solution were determined by flame atomic absorption spectrometry .The results show that the detection limit of potassium and sodium are 0 .020 mg/L and 0 .004 mg/L ,respectively .The recovery rate and RSD of potassium are 102 .5% and 3% (n=6) ,the recovery rate and RSD of sodium are 97% and 2 .5% (n=6) .%硝酸钍样品经水溶解后,在酸性介质中加入氯化铯消除电离干扰,采用火焰原子吸收法测定钾、钠。结果表明:方法检出限为0.020 m g/L (钾)和0.004 m g/L (钠);钾回收率为102.5%,测定结果的相对标准偏差为3.0%(n=6);钠回收率为97.0%,测定结果的相对标准偏差为2.5%(n=6)。

  20. Trends in speciation analysis of some heavy metals in serum of patients with chronic hepatitis C and chronic hepatitis B using differential pulse adsorptive stripping voltammetric measurement and atomic absorption spectrophotometry.

    Science.gov (United States)

    Rashed, Mohamed Nageeb; Ahmed, Mahasen Mohamed; Al-Hossainy, Ahmed Farouk; Abd, Safaa Mahmoud

    2010-04-01

    The relationships between chronic liver diseases and trace heavy metal contents in blood are debatable and have not been understood clearly. The present study is undertaken to determine Co, Fe, and Ni concentrations in sera from viral hepatitis patients. In all eighty patients with chronic hepatitis (B, C) and 29 healthy individuals were chosen for this study. Donors were selected from different environmental areas, including Aswan, Kom Ombo, and Edfu as polluted areas, and Daraw as an unpolluted area. Co, Fe, and Ni concentrations in patient and healthy blood serum were measured by two different analytical techniques: differential pulse adsorptive stripping voltammetry (DPA(d)SV) and atomic absorption spectrophotometer (AAS). The results reveal that Fe is present in higher level in the blood serum of hepatitis patients than in the healthy control, whereas Co and Ni showed the opposite trend. Hepatitis patients from Edfu area exhibited higher Fe level in their serum than those from the other areas, while hepatitis patients and healthy control from Daraw area (free from pollution) exhibited the lowest metal values. Patients with hepatitis C show lower levels of Co, Ni, and Fe in their serum than those with hepatitis B. A comparative study was carried out between the results using DPA(d)SV and AAS techniques, which are in very good agreements. 2009 Elsevier GmbH. All rights reserved.

  1. Determination of molecular line parameters for acrolein (C(3)H(4)O) using infrared tunable diode laser absorption spectroscopy.

    Science.gov (United States)

    Harward, Charles N; Thweatt, W David; Baren, Randall E; Parrish, Milton E

    2006-04-01

    Acrolein (C(3)H(4)O) molecular line parameters, including infrared (IR) absorption positions, strengths, and nitrogen broadened half-widths, must be determined since they are not included in the high resolution transmission (HITRAN) molecular absorption database of spectral lines. These parameters are required for developing a quantitative analytical method for measuring acrolein in a single puff of cigarette smoke using tunable diode laser absorption spectroscopy (TDLAS). The task is complex since acrolein has many highly overlapping infrared absorption lines in the room temperature spectrum and the cigarette smoke matrix contains thousands of compounds. This work describes the procedure for estimating the molecular line parameters for these overlapping absorption lines in the wavenumber range (958.7-958.9 cm(-1)) using quantitative reference spectra taken with the infrared lead-salt TDLAS instrument at different pressures and concentrations. The nitrogen broadened half-width for acrolein is 0.0937 cm(-1)atm(-1) and to our knowledge, is the first time it has been reported in the literature.

  2. Signatures of Hot Molecular Hydrogen Absorption from Protoplanetary Disks. I. Non-thermal Populations

    Science.gov (United States)

    Hoadley, Keri; France, Kevin; Arulanantham, Nicole; Parke Loyd, R. O.; Kruczek, Nicholas

    2017-09-01

    The environment around protoplanetary disks (PPDs) regulates processes that drive the chemical and structural evolution of circumstellar material. We perform a detailed empirical survey of warm molecular hydrogen (H2) absorption observed against H i-Lyα (Lyα: λ1215.67) emission profiles for 22 PPDs, using archival Hubble Space Telescope ultraviolet (UV) spectra to identify H2 absorption signatures and quantify the column densities of H2 ground states in each sightline. We compare thermal equilibrium models of H2 to the observed H2 rovibrational level distributions. We find that, for the majority of targets, there is a clear deviation in high-energy states (T exc ≳ 20,000 K) away from thermal equilibrium populations (T(H2) ≳ 3500 K). We create a metric to estimate the total column density of non-thermal H2 (N(H2)nLTE) and find that the total column densities of thermal (N(H2)) and N(H2)nLTE correlate for transition disks and targets with detectable C iv-pumped H2 fluorescence. We compare N(H2) and N(H2)nLTE to circumstellar observables and find that N(H2)nLTE correlates with X-ray and far-UV luminosities, but no correlations are observed with the luminosities of discrete emission features (e.g., Lyα, C iv). Additionally, N(H2) and N(H2)nLTE are too low to account for the H2 fluorescence observed in PPDs, so we speculate that this H2 may instead be associated with a diffuse, hot, atomic halo surrounding the planet-forming disk. We create a simple photon-pumping model for each target to test this hypothesis and find that Lyα efficiently pumps H2 levels with T exc ≥ 10,000 K out of thermal equilibrium.

  3. Electronic absorption and resonance Raman spectroscopy from ab initio quantum molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Nun, M.; Martinez, T.J.

    1999-12-09

    The absorption and resonance Raman excitation profiles of ethylene following {pi} {yields} {pi}* excitation and taking full account of anharmonicity and Duschinsky rotation effects are calculated from first principles molecular dynamics using the ab initio multiple spawning (AIMS) method and a correlation function approach. The AIMS method solves the nuclear and electronic Schroedinger equations simultaneously and it associates a unique nuclear wave function with each electronic state. The compound absorption spectrum has a full width at half maximum of 9,800 and 1,300 cm{sup {minus}1} (in agreement with the experimental value, 9,500 cm{sup {minus}1}) and a high-frequency structure spaced by 800 and 10 cm{sup {minus}1}, attributed to C{double{underscore}bond}C stretching. The resonance Raman excitation profile exhibits fundamental activity in all totally symmetric modes with the C{double{underscore}bond}C stretching mode being the most dominant. In addition, overtone activity is observed in the torsional motion, out-of-plane wagging motions and the out-of-plane rocking motions. The activity is consistent with the observation that the first excited state is twisted and one of the CH{sub 2} groups is pyramidalized. The coordinate dependence of the electronic transition dipole is investigated, and they find that it depends very strongly on the torsional coordinate and less so on the pyramidalization and C{double{underscore}bond}C stretching coordinates. However, within the approximations used in this paper this dependence does not influence the spectra significantly and the Condon approximation is quite accurate.

  4. Probing autoionizing states of molecular oxygen with XUV transient absorption: Electronic symmetry dependent lineshapes and laser induced modification

    CERN Document Server

    Liao, Chen-Ting; Haxton, Daniel J; Rescigno, Thomas N; Lucchese, Robert R; McCurdy, C William; Sandhu, Arvinder

    2016-01-01

    The dynamics of autoionizing Rydberg states of oxygen are studied using attosecond transient absorption technique, where extreme ultraviolet (XUV) initiates molecular polarization and near infrared (NIR) pulse perturbs its evolution. Transient absorption spectra show positive optical density (OD) change in the case of $ns\\sigma_g$ and $nd\\pi_g$ autoionizing states of oxygen and negative OD change for $nd\\sigma_g$ states. Multiconfiguration time-dependent Hartree-Fock (MCTDHF) calculation are used to simulate the transient absorption spectra and their results agree with experimental observations. The time evolution of superexcited states is probed in electronically and vibrationally resolved fashion and we observe the dependence of decay lifetimes on effective quantum number of the Rydberg series. We model the effect of near-infrared (NIR) perturbation on molecular polarization and find that the laser induced phase shift model agrees with the experimental and MCTDHF results, while the laser induced attenuation...

  5. Solvent effect on the absorption spectra of coumarin 120 in water: A combined quantum mechanical and molecular mechanical study.

    Science.gov (United States)

    Sakata, Tetsuya; Kawashima, Yukio; Nakano, Haruyuki

    2011-01-07

    The solvent effect on the absorption spectra of coumarin 120 (C120) in water was studied utilizing the combined quantum mechanical∕molecular mechanical (QM∕MM) method. In molecular dynamics (MD) simulation, a new sampling scheme was introduced to provide enough samples for both solute and solvent molecules to obtain the average physical properties of the molecules in solution. We sampled the structure of the solute and solvent molecules separately. First, we executed a QM∕MM MD simulation, where we sampled the solute molecule in solution. Next, we chose random solute structures from this simulation and performed classical MD simulation for each chosen solute structure with its geometry fixed. This new scheme allowed us to sample the solute molecule quantum mechanically and sample many solvent structures classically. Excitation energy calculations using the selected samples were carried out by the generalized multiconfigurational perturbation theory. We succeeded in constructing the absorption spectra and realizing the red shift of the absorption spectra found in polar solvents. To understand the motion of C120 in water, we carried out principal component analysis and found that the motion of the methyl group made the largest contribution and the motion of the amino group the second largest. The solvent effect on the absorption spectrum was studied by decomposing it in two components: the effect from the distortion of the solute molecule and the field effect from the solvent molecules. The solvent effect from the solvent molecules shows large contribution to the solvent shift of the peak of the absorption spectrum, while the solvent effect from the solute molecule shows no contribution. The solvent effect from the solute molecule mainly contributes to the broadening of the absorption spectrum. In the solvent effect, the variation in C-C bond length has the largest contribution on the absorption spectrum from the solute molecule. For the solvent effect on the

  6. Determination of Titanium in Water by Graphite Furnace Atomic Absorption Spectrophotometry%石墨炉原子吸收分光光度法测定水中钛

    Institute of Scientific and Technical Information of China (English)

    杜青; 任兰

    2016-01-01

    The method for determination of soluble titanium and total titanium in water by graphite furnace atomic absorption spectrometry was established. Soluble titanium sample was filtered by 0.45μm microporous membrane and total titanium sample was digested by different regent–nitric acid,hydrogen peroxide,sulfuric aicd and their combination according to different type of sample. The optimal measurement parameters and graphite tube available were developed through experiments. Co-existent element interference was undetected in normal samples. The method was verified by six laboratories, the linear range was 0–250μg/L,the detection limit was 4.0μg/L for soluted titanium and 7.0μg/L for total titanium,the RSD of determination results was not more than 12%(n=6), and the recoveries ranged from 90.0%to 107%. The relative error of determination results of Ti standard material with this method ranged from–3.4%to 2.4%. This method is accurate and reliable with less interference and easy to be popularized and applied.%建立石墨炉原子吸收分光光度法测定水中痕量可溶性钛和总钛。测量可溶性钛的样品通过0.45μm水系微孔滤膜过滤后直接测定,测量总钛的样品根据不同类型采用硝酸、过氧化氢、硫酸的不同组合进行消解。通过试验确定了最佳石墨炉程序升温工作条件和热解涂层石墨管的应用。干扰试验表明水中常见共存离子不干扰钛的测定。本方法经6家实验室验证,在0~250μg/L范围内线性良好,方法检出限可溶性钛为4.0μg/L,总钛为7.0μg/L。测定结果的相对标准偏差不大于12%(n=6),加标回收率为90.0%~107%,该方法对钛标准物质测定结果的相对误差为–3.4%~2.4%。该方法准确、可靠,检出限低,干扰少,易于推广应用。

  7. Isotopic ratios at z = 0.68 from molecular absorption lines toward B 0218+357

    Science.gov (United States)

    Wallström, S. H. J.; Muller, S.; Guélin, M.

    2016-11-01

    Isotopic ratios of heavy elements are a key signature of the nucleosynthesis processes in stellar interiors. The contribution of successive generations of stars to the metal enrichment of the Universe is imprinted on the evolution of isotopic ratios over time. We investigate the isotopic ratios of carbon, nitrogen, oxygen, and sulfur through millimeter molecular absorption lines arising in the z = 0.68 absorber toward the blazar B 0218+357. We find that these ratios differ from those observed in the Galactic interstellar medium, but are remarkably close to those in the only other source at intermediate redshift for which isotopic ratios have been measured to date, the z = 0.89 absorber in front of PKS 1830-211. The isotopic ratios in these two absorbers should reflect enrichment mostly from massive stars, and they are indeed close to the values observed toward local starburst galaxies. Our measurements set constraints on nucleosynthesis and chemical evolution models. The reduced spectra 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/595/A96

  8. Molecular engineering of nanoscale quadrupolar chromophores for two-photon absorption

    Science.gov (United States)

    Porres, Laurent; Mongin, Olivier; Blanchard-Desce, Mireille H.; Ventelon, Lionel; Barzoukas, Marguerite; Moreaux, Laurent; Pons, Thomas; Mertz, Jerome

    2003-02-01

    Our aim has been the design of optimized NLO-phores with very high two-photon absorption (TPA) cross-sections (s2) in the red-NIR region, while maintaining high linear transparency and high fluorescence quantum yield. Our molecular engineering strategy is based on the push-push or pull-pull functionalization of semi-rigid nanoscale conjugated systems. The central building blocks were selected as rigid units that may assist quadrupolar intramolecular charge transfer by acting either as a (weak) donor or acceptor core. Quadrupolar molecules derived either from a phenyl unit, a rigidified biphenyl moiety or a fused bithiophene unit have been considered. Conjugated oligomers made of phenylene-vinylene and/or phenylene-ethynylene units were selected as connecting spacers between the core and the electroactive end groups to ensure effective electronic conjugation while maintaining suitable transparency/fluorescence. The TPA cross-sections were determined by investigating the two-photon-excited fluorescence properties using a Ti:sapphire laser delivering fs pulses. Both the nature of the end groups and of the core moiety play an important role in determining the TPA spectra. In addition, by adjusting the length and nature of the conjugated extensor, both amplification and spectral tuning of TPA cross-sections can be achieved. As a result, push-push fluorophores which demonstrate giant TPA cross-sections (up to 3000 GM) in the visible red, high fluorescence quantum yields and good transparency in the visible range have been obtained.

  9. Fluorine determination in coal using high-resolution graphite furnace molecular absorption spectrometry and direct solid sample analysis

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Patrícia M.; Morés, Silvane; Pereira, Éderson R. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Welz, Bernhard, E-mail: w.bernardo@terra.com.br [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil); Carasek, Eduardo [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Andrade, Jailson B. de [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil)

    2015-03-01

    The absorption of the calcium mono-fluoride (CaF) molecule has been employed in this study for the determination of fluorine in coal using direct solid sample analysis and high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS). The rotational line at 606.440 nm was used for measuring the molecular absorption in the gas phase. The pyrolysis and vaporization temperatures were 700 °C and 2100 °C, respectively. Different chemical modifiers have been studied, such as Pd and Ir as permanent modifiers, and Pd and the mixed Pd/Mg modifier in solution. The limit of detection and the characteristic mass were 0.3 and 0.1 ng F, respectively. One certified reference material (CRM) of coal (NIST 1635) and four CRMs with a non-certified value for F (SARM 18, SARM 20, BCR 40, BCR 180) were used to evaluate the accuracy and precision of the method, obtaining good agreement (104%) with the certified value and with the informed values (ranging from 90 to 103%). - Highlights: • High-resolution Graphite Furnace Molecular Absorption Spectrometry (HR-GF MAS) • Fluorine has been determined using HR-GF MAS of the CaF molecule. • The CaF molecule was generated in a graphite furnace at a temperature of 2100 °C • Coal samples have been analyzed using direct solid sample introduction. • Aqueous standard solutions have been used for calibration.

  10. Quantificação laboratorial de cobre sérico por espectrofotometria Vis comparável à espectrometria de absorção atômica com chama Laboratorial quantification of serum copper by Vis spectrophotometry in comparison to flame atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Angela Maria Moro

    2007-08-01

    Full Text Available INTRODUÇÃO: O cobre é um nutriente essencial para os humanos, e a manutenção dos seus níveis é importante, uma vez que seu metabolismo está envolvido com estresse oxidativo e patologias, como a Doença de Wilson. Neste trabalho, um método de espectrofotometria visível (espectrofotometria Vis foi validado, aplicado em indivíduos jovens e comparado com espectrometria de absorção atômica com chama (EAA-chama. MÉTODOS: Concentrações séricas de cobre foram medidas por EAA-chama e por espectrofotometria Vis, através da reação de cobre com batocuproína, l = 484 nm. Curvas analíticas em solução aquosa e com adição de padrão foram efetuadas para verificar linearidade, recuperação e precisão do método espectrofotométrico. Amostras de sangue de 12 indivíduos (média de idade 22 anos foram analisadas por ambos os métodos e comparadas entre si. Os resultados foram expressos em média ± desvio-padrão. RESULTADOS: As curvas com adição de padrão e aquosa (n = 5 apresentaram coeficientes de regressão superiores a 0,99 e de variação inter e intradia inferiores a 15%. Os valores de cobre sérico encontrados para o método espectrofotométrico foram 1,17 ± 0,39 e 0,73 ± 0,14 mg/l para mulheres e homens, respectivamente. Para EAA-chama foram encontrados 1,13 ± 0,43 e 0,59 ± 0,13 mg/l para mulheres e homens, respectivamente. Os resultados mostraram correlação de Pearson significativa (r = 0,946; p BACKGROUND: Copper is an essential nutrient for humans and maintenance of its adequate levels is important, since its metabolism is involved with oxidative stress and patolologies, such as Wilson's disease. In this work, a visible spectrophotometric method was validated, applied in young subjects and compared to flame atomic absorption spectrometry (FAAS in serum copper levels determination. METHODS: Serum copper concentrations were measured by FAAS and by spectrophotometry, through copper reaction with bathocuproine, l = 484

  11. Rototranslational collision-induced absorption and collision-induced light scattering spectra of molecular hydrogen using isotropic intermolecular potentials

    Science.gov (United States)

    El-Kader, M. S. A.; Maroulis, G.; Bich, E.

    2012-07-01

    Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures and of collision-induced light scattering (CILS) at room temperature are computed for gaseous molecular hydrogen using theoretical values for induced dipole moments and pair-polarizability trace and anisotropy as input. Comparison with measured spectra of absorption, isotropic and anisotropic light scattering shows satisfactory agreement, for which the uncertainty in measurement of its spectral moments is seen to be large. Empirical models of the dipole moment and pair-polarizability trace and anisotropy which reproduce the experimental spectra and the first three spectral moments more closely than the fundamental theory are also given. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when potential models which are constructed from the thermophysical, transport, total scattering cross-section and spectroscopic properties are used. Also, the use of the new potential in lattice dynamic calculations yields good results for several properties of solid hydrogen.

  12. The contribution of molecular relaxation in nitrogen to the absorption of sound in the atmosphere

    Science.gov (United States)

    Zuckerwar, A. J.; Meredith, R. W.

    1980-01-01

    Results and statistical analysis are presented for sound absorption in N2-H2O binary mixtures at room temperature. Experimental procedure, temperature effects, and preliminary results are presented for sound absorption in N2-H2O binary mixtures at elevated temperatures.

  13. The 9.7 and 18 um silicate absorption profiles towards diffuse and molecular cloud lines-of-sight

    CERN Document Server

    van Breemen, J M; Chiar, J E; Waters, L B F M; Kemper, F; Boogert, A C A; Cami, J; Decin, L; Knez, C; Sloan, G C; Tielens, A G G M

    2010-01-01

    Studying the composition of dust in the interstellar medium (ISM) is crucial in understanding the cycle of dust in our galaxy. The mid-infrared spectral signature of amorphous silicates, the most abundant dust species in the ISM, is studied in different lines-of-sight through the Galactic plane, thus probing different conditions in the ISM. We have analysed 10 spectra from the Spitzer archive, of which 6 lines-of-sight probe diffuse interstellar medium material and 4 probe molecular cloud material. The 9.7 um silicate absorption features in 7 of these spectra were studied in terms of their shape and strength. In addition, the shape of the 18 um silicate absorption features in 4 of the diffuse sightline spectra were analysed. The 9.7 um silicate absorption bands in the diffuse sightlines show a strikingly similar band shape. This is also the case for all but one of the 18 um silicate absorption bands observed in diffuse lines-of-sight. The 9.7 um bands in the 4 molecular sightlines show small variations in sha...

  14. Direct determination of fluorine in niobium oxide using slurry sampling electrothermal high-resolution continuum source molecular absorption spectrometry

    Science.gov (United States)

    Huang, Mao Dong; Becker-Ross, Helmut; Okruss, Michael; Geisler, Sebastian; Florek, Stefan; Richter, Silke; Meckelburg, Angela

    Aiming for a round-robin test, a new method for the direct determination of fluorine in niobium oxide has been developed. It is based on the use of high-resolution molecular absorption spectra of calcium mono-fluoride (CaF) generated in the graphite tube, combined with the slurry sampling technique. The absorption measurement was performed at the 606.44 nm CaF rotational line. By using graphite tubes with zirconium carbide (ZrC) modified platform, the molecular absorption sensitivity of CaF has been improved by a factor of 20, and no additional chemical modifier was necessary. Generally, non-spectral interferences were observed in the presence of HCl, H2SO4, and H3PO4. For HCl, additional spectral interference occurred due to an overlap of the absorption spectra of CaF and CaCl. However, due to the absence of these mentioned substances in the current material, such interferences do not exist for this application. The characteristic mass found for the CaF 606.44 nm line was 0.1 ng; the limit of detection was 5 mg fluorine per kg solid sample (3σ criterion). The results obtained by the method were within the range of certified values. Comparing to the classical method such as the pyrohydrolysis-photometric method, the developed new method showed clear advantages regarding sensitivity and specificity. The time requirement for one sample analysis was strongly shortened from several hours to only some minutes.

  15. Equilibrium Structures and Absorption Spectra for SixOy-nH2O Molecular Clusters using Density Functional Theory

    Science.gov (United States)

    2017-05-04

    College, City University of New York, New York, NY 10065 ONR Absorption spectra Density Functional Theory Molecular clusters Contents Introduction ...Clusters using Density Functional Theory May 4, 2017 Approved for public release; distribution is unlimited. L. Huang S.g. LambrakoS Center for...reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching

  16. A discrete interaction model/quantum mechanical method to describe the interaction of metal nanoparticles and molecular absorption.

    Science.gov (United States)

    Morton, Seth Michael; Jensen, Lasse

    2011-10-07

    A frequency-dependent quantum mechanics/molecular mechanics method for the calculation of response properties of molecules adsorbed on metal nanoparticles is presented. This discrete interaction model/quantum mechanics (DIM/QM) method represents the nanoparticle atomistically, thus accounting for the local environment of the nanoparticle surface on the optical properties of the adsorbed molecule. Using the DIM/QM method, we investigate the coupling between the absorption of a silver nanoparticle and of a substituted naphthoquinone. This system is chosen since it shows strong coupling due to a molecular absorption peak that overlaps with the plasmon excitation in the metal nanoparticle. We show that there is a strong dependence not only on the distance of the molecule from the metal nanoparticle but also on its orientation relative to the nanoparticle. We find that when the transition dipole moment of an excitation is oriented towards the nanoparticle there is a significant increase in the molecular absorption as a result of coupling to the metal nanoparticle. In contrast, we find that the molecular absorption is decreased when the transition dipole moment is oriented parallel to the metal nanoparticle. The coupling between the molecule and the metal nanoparticle is found to be surprisingly long range and important on a length scale comparable to the size of the metal nanoparticle. A simple analytical model that describes the molecule and the metal nanoparticle as two interacting point objects is found to be in excellent agreement with the full DIM/QM calculations over the entire range studied. The results presented here are important for understanding plasmon-exciton hybridization, plasmon enhanced photochemistry, and single-molecule surface-enhanced Raman scattering.

  17. The Far‐Infrared Spectrum of the Sagittarius B2 Region: Extended Molecular Absorption, Photodissociation, and Photoionization

    OpenAIRE

    Goicoechea, Javier R.; Nemesio J. Rodríguez-Fernández; Cernicharo, José

    2003-01-01

    We present large scale 9'x 27'(25 pc x 70 pc) far-IR observations around Sgr B2 using the Long-wavelength spectrometer (LWS) on board the Infrared Space Observatory (ISO). The spectra are dominated by the strong continuum emission of dust, the widespread molecular absorption of light hydrides (OH, CH and H2O) and the fine structure lines of [NII], [NIII], [OIII], [CII] and [OI]. The molecular richness in the outer layers of Sgr B2 is probed by the ISO-LWS Fabry-Perot (35 km s^-1) detections t...

  18. Simultaneous determination of cobalt and nickel in alloy steel by microwave digestion-dual wavelength equal absorption spectrophotometry%微波消解-双波长等吸收分光光度法同时测定合金钢中钴和镍

    Institute of Scientific and Technical Information of China (English)

    李丽华; 张金生; 尹学博; 高昌录

    2001-01-01

    研究并确定了微波消解合金钢的最佳条件,应用双波长等吸收方法解决了PAR-Co2+,Ni2+体系中Co2+,Ni2+同时测定问题。测定了标准合成样品中的Co2+和Ni2+,其回收率分别在98.2%~103.6%和97.9%~103.7%之间。对多种合金钢样品中Co2+和Ni2+进行测定,钴和镍的相对标准偏差分别≤1.00%和≤1.10%;相对误差分别≤±2.5%和≤±2.0%,均优于常压消解合金钢样品所得结果。采用本法测定合金钢中钴和镍,快速、准确、样品损失少、酸用量少,并大大降低环境污染。%In this paper, alloy steel samples are digested in the sealed vessel by the microwave digestion system. The optimum parameters for microwave digestion are studied and selected. Cobalt and nickel in the colored system of Co2+ and Ni2+ 4-(2-pyridylazo) resorcinol (PAR) can be determined simultaneously by dual-wavelength equal absorption spectrophotometry. The recoveries of Co2+ and Ni2+ in synthetic samples are within 98.2%-103.6% and within 97.9%-103.7%, respectively. The relative standard deviations of analytical results in alloy steel are less than 1.00% for Co2+ and less than 1.10% for Ni2+, and relative errors are less than ±2.5% for Co2+ and less than ±2.0% for Ni2+. These results are all less than those of digestion in atmosphere. The experimental results show that the method is rapid, precise, and less contaminative.

  19. Molecular design for improved photovoltaic efficiency: band gap and absorption coefficient engineering

    KAUST Repository

    Mondal, Rajib

    2009-01-01

    Removing the adjacent thiophene groups around the acceptor core in low band gap polymers significantly enhances solar cell efficiency through increasing the optical absorption and raising the ionization potential of the polymer. © 2009 The Royal Society of Chemistry.

  20. Mechanisms and Regulation of Intestinal Absorption of Water-soluble Vitamins: Cellular and Molecular Aspects

    DEFF Research Database (Denmark)

    Nexø, Ebba; Said, Hamid M

    2012-01-01

    The water-soluble vitamins represent a group of structurally and functionally unrelated compounds that share the common feature of being essential for normal cellular functions, growth, and development. With the exception of some endogenous production of niacin, human cells cannot synthesize...... or deficiency. An impaired absorptive function occurs in a variety of conditions including congenital defects in the digestive or absorptive processes, intestinal diseases, drug interaction, and chronic alcohol use....

  1. Mid-infrared absorption spectra of dimethyl methylphosphonate as molecular simulant of nerve agents

    Institute of Scientific and Technical Information of China (English)

    Yonggang Zhang; Zhenxing Cheng; Aizhen Li; Songlin Feng

    2006-01-01

    The fine mid-infrared absorption features of dimethyl methylphosphonate vapor have been characterized by using Fourier transforms infrared spectroscopy, and the nitrous oxide was used for calibration purpose. The results show that the main P-O-C and P=O bonds related absorption bands of dimethyl methylphosphonate vapor are peaked at 1050.01 and 1275.76 cm-1 respectively, those two bands show continuous characteristics at resolution of 0.125 cm-1.

  2. Highly specific spectroscopic photoacoustic molecular imaging of dynamic optical absorption shifts of an antibody-ICG contrast agent (Conference Presentation)

    Science.gov (United States)

    Wilson, Katheryne E.; Bachawal, Sunitha; Abou-Elkacem, Lotfi; Jensen, Kristen C.; Machtaler, Steven; Tian, Lu; Willmann, Juergen K.

    2017-03-01

    Improved techniques for breast cancer screening are critically needed as current methods lack diagnostic accuracy. Using spectroscopic photoacoustic (sPA) molecular imaging with a priori knowledge of optical absorption spectra allows suppression of endogenous background signal, increasing the overall sensitivity and specificity of the modality to exogenous contrast agents. Here, sPA imaging was used to monitor antibody-indocyanine green (ICG) conjugates as they undergo optical absorption spectrum shifts after cellular endocytosis and degradation to allow differentiation between normal murine mammary glands from breast cancer by enhancing molecular imaging signal from target (B7-H3)-bound antibody-ICG. First, B7-H3 was shown to have highly specific (AUC of 0.93) expression on both vascular endothelium and tumor stroma in malignant lesions through quantitative immunohistochemical staining of B7-H3 on 279 human samples (normal (n=53), benign lesions (11 subtypes, n=182), breast cancers (4 subtypes, n=97)), making B7-H3 a promising target for sPA imaging. Second, absorption spectra of intracellular and degraded B7-H3-ICG and Isotype control (Iso-ICG) were characterized through in vitro and in vivo experiments. Finally, a transgenic murine breast cancer model (FVB/N-Tg(MMTVPyMT)634Mul) was imaged, and sPA imaging in found a 3.01 (IQR 2.63, 3.38, Panimals (n=60), Iso-ICG (n=30), blocking B7-H3+B7-H3-ICG (n=20), and free ICG (n=20)) despite significant tumor accumulation of Iso-ICG, confirmed through ex vivo histology. Overall, leveraging anti-B7-H3 antibody-ICG contrast agents, which have dynamic optical absorption spectra representative of molecular interactions, allows for highly specific sPA imaging of murine breast cancer.

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

    Science.gov (United States)

    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.

  4. Evidence for strong electron correlations in graphene molecular fragments: Theory and experiments on two-photon absorptions

    Science.gov (United States)

    Aryanpour, Karan; Roberts, Adam; Sandhu, Arvinder; Shukla, Alok; Mazumdar, Sumit

    2013-03-01

    Historically, the occurrence of the lowest two-photon state below the optical one-photon state in linear polyenes, polyacetylenes and polydiacetylenes provided the strongest evidence for strong electron correlations in these linear π-conjugated systems. We demonstrate similar behavior in several molecular fragments of graphene with D6 h symmetry, theoretically and experimentally. Theoretically, we have calculated one versus two-photon absorptions in coronene, two different hexabenzocoronenes and circumcoronene, within the Pariser-Parr-Pople π-electron Hamiltonian using high order configuration interaction. Experimentally, we have performed z-scan measurements using a white light super-continuum source on coronene and hexa-peri-hexabenzocoronene to determine frequency-dependent two-photon absorption coefficients, for comparison to the ground state absorptions. Excellent agreement between experiment and theory in our work gives strong evidence for significant electron correlations between the π-electrons in the graphene molecular fragments. We particularly benchmark high order electron-hole excitations in graphene fragments as a key element behind the agreement between theory and experiment in this work. We acknowledge NSF-CHE-1151475 grant as our funding source.

  5. Conjugate spacer effect on molecular structures and absorption spectra of triphenylamine dyes for sensitized solar cells: density functional theory calculations.

    Science.gov (United States)

    Xu, Jie; Wang, Lei; Liang, Guijie; Bai, Zikui; Wang, Luoxin; Xu, Weilin; Shen, Xiaolin

    2011-01-01

    The molecular structures and absorption spectra of triphenylamine dyes containing variable thiophene units as the spacers (TPA1-TPA3) were investigated by density functional theory (DFT) and time-dependent DFT. The calculated results indicate that the strong conjugation is formed in the dyes and the length of conjugate bridge increases gradually with the increased thiophene spacers. The interfacial charge transfer between the TiO2 electrode and TPA1-TPA3 are electron injection processes from the excited dyes to the semiconductor conduction band. The simulated absorption bands are assigned to π→π* transitions, which exhibit appreciable red-shift with respect to the experimental bands due to the lack of direct solute-solvent interaction and the inherent approximations in TD-DFT. The effect of thiophene spacers on the molecular structures, absorption spectra and photovoltaic performance were comparatively discussed and points out that the choice of appropriate conjugate bridge is very important for the design of new dyes with improved performance.

  6. Fluorine determination in coal using high-resolution graphite furnace molecular absorption spectrometry and direct solid sample analysis

    Science.gov (United States)

    Machado, Patrícia M.; Morés, Silvane; Pereira, Éderson R.; Welz, Bernhard; Carasek, Eduardo; de Andrade, Jailson B.

    2015-03-01

    The absorption of the calcium mono-fluoride (CaF) molecule has been employed in this study for the determination of fluorine in coal using direct solid sample analysis and high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS). The rotational line at 606.440 nm was used for measuring the molecular absorption in the gas phase. The pyrolysis and vaporization temperatures were 700 °C and 2100 °C, respectively. Different chemical modifiers have been studied, such as Pd and Ir as permanent modifiers, and Pd and the mixed Pd/Mg modifier in solution. The limit of detection and the characteristic mass were 0.3 and 0.1 ng F, respectively. One certified reference material (CRM) of coal (NIST 1635) and four CRMs with a non-certified value for F (SARM 18, SARM 20, BCR 40, BCR 180) were used to evaluate the accuracy and precision of the method, obtaining good agreement (104%) with the certified value and with the informed values (ranging from 90 to 103%).

  7. Rototranslational collision-induced absorption and collision-induced light scattering spectra of molecular hydrogen using isotropic intermolecular potentials

    Energy Technology Data Exchange (ETDEWEB)

    El-Kader, M.S.A., E-mail: Mohamedsay68@hotmail.com [Department of Engineering Mathematics and Physics, Faculty of Engineering, Cairo University, Giza 12211 (Egypt); Maroulis, G. [Department of Chemistry, University of Patras, GR-26500 Patras (Greece); Bich, E. [Institut fuer Chemie, Universitaet Rostock Albert-Einstein-Strasse 3a, D-18059 Rostock (Germany)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer We have determined an isotropic intermolecular potential for the interaction of hydrogen. Black-Right-Pointing-Pointer The thermophysical and transport properties are calculated for this system. Black-Right-Pointing-Pointer The rovibrational energy levels and scattering cross-sections are determined. Black-Right-Pointing-Pointer We have adopted a model for the induced dipole moment {mu}(r) with adjustable parameters. Black-Right-Pointing-Pointer The quantum lineshapes of absorption and scattering are calculated. -- Abstract: Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures and of collision-induced light scattering (CILS) at room temperature are computed for gaseous molecular hydrogen using theoretical values for induced dipole moments and pair-polarizability trace and anisotropy as input. Comparison with measured spectra of absorption, isotropic and anisotropic light scattering shows satisfactory agreement, for which the uncertainty in measurement of its spectral moments is seen to be large. Empirical models of the dipole moment and pair-polarizability trace and anisotropy which reproduce the experimental spectra and the first three spectral moments more closely than the fundamental theory are also given. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when potential models which are constructed from the thermophysical, transport, total scattering cross-section and spectroscopic properties are used. Also, the use of the new potential in lattice dynamic calculations yields good results for several properties of solid hydrogen.

  8. Absorption and fluorescence of PRODAN in phospholipid bilayers: a combined quantum mechanics and classical molecular dynamics study.

    Science.gov (United States)

    Cwiklik, Lukasz; Aquino, Adelia J A; Vazdar, Mario; Jurkiewicz, Piotr; Pittner, Jiří; Hof, Martin; Lischka, Hans

    2011-10-20

    Absorption and fluorescence spectra of PRODAN (6-propionyl-2-dimethylaminonaphthalene) were studied by means of the time-dependent density functional theory and the algebraic diagrammatic construction method. The influence of environment, a phosphatidylcholine lipid bilayer and water, was taken into account employing a combination of quantum chemical calculations with empirical force-field molecular dynamics simulations. Additionally, experimental absorption and emission spectra of PRODAN were measured in cyclohexane, water, and lipid vesicles. Both planar and twisted configurations of the first excited state of PRODAN were taken into account. The twisted structure is stabilized in both water and a lipid bilayer, and should be considered as an emitting state in polar environments. Orientation of the excited dye in the lipid bilayer significantly depends on configuration. In the bilayer, the fluorescence spectrum can be regarded as a combination of emission from both planar and twisted structures.

  9. MSG-7: Molecular absorption processes related to the penetration of ultraviolet solar radiation into the middle atmosphere

    Science.gov (United States)

    Frederick, J. E.; Blake, A. J.; Freeman, D. E.; Nicholls, R. W.; Ogawa, T.; Simon, P. C.

    1983-01-01

    The information presently available on the absorption cross sections of O2 and O3 with attention to the application of these data in middle atmospheric science is reviewed. The cross sections values reported by different groups are intercompared in tabular form where feasible, and specific values are recommended when there is a basis for preferring a particular set of results over other available data. When no such basis exists, the differences among published cross sections then serve to indicate a range of uncertainty. In these cases the need for additional work is indicated. Specific topics addressed are the absorption of molecular oxygen at Lyman alpha, in the Schumann-Runge continuum, in the Schumann-Runge bands, and in the Herzberg continuum. For ozone, the Hartley and Huggins bands are considered.

  10. Direct correlation of charge transfer absorption with molecular donor:acceptor interfacial area via photothermal deflection spectroscopy

    KAUST Repository

    Domingo, Ester

    2015-04-09

    We show that the Charge Transfer (CT) absorption signal in bulk-heterojunction (BHJ) solar cell blends, measured by photothermal deflection spectroscopy (PDS), is directly proportional to the density of molecular donor/acceptor interfaces. Since the optical transitions from ground state to the interfacial CT state are weakly allowed at photon energies below the optical gap of both donor and acceptor, we can exploit the use of this sensitive linear absorption spectroscopy for such quantification. Moreover, we determine the absolute molar extinction coefficient of the CT transition for an archetypical polymer-fullerene interface. The latter is ~100 times lower than the extinction coefficient of the donor chromophore involved, allowing us to experimentally estimate the transition dipole moment (0.3 D) and the electronic coupling between ground state and CT state to be on the order of 30 meV.

  11. Duodenal calcium absorption in vitamin D receptor-knockout mice: functional and molecular aspects.

    NARCIS (Netherlands)

    Cromphaut, S.J. van; Dewerchin, M.; Hoenderop, J.G.J.; Stockmans, I.; Herck, E. van; Kato, S.; Bindels, R.J.M.; Collen, D.; Carmeliet, P.; Bouillon, R.; Carmeliet, G.

    2001-01-01

    Rickets and hyperparathyroidism caused by a defective vitamin D receptor (VDR) can be prevented in humans and animals by high calcium intake, suggesting that intestinal calcium absorption is critical for 1,25(OH)(2) vitamin D [1,25(OH)(2)D(3)] action on calcium homeostasis. We assessed the rate of s

  12. Determination of bimetallic architectures in nanometer-scale catalysts by combining molecular dynamics simulations with x-ray absorption spectroscopy

    Science.gov (United States)

    Timoshenko, Janis; Keller, Kayla R.; Frenkel, Anatoly I.

    2017-03-01

    Here we present an approach for the determination of an atomic structure of small bimetallic nanoparticles by combining extended X-ray absorption fine structure spectroscopy and classical molecular dynamics simulations based on the Sutton-Chen potential. The proposed approach is illustrated in the example of PdAu nanoparticles with ca 100 atoms and narrow size and compositional distributions. Using a direct modeling approach and no adjustable parameters, we were able to reproduce the size and shape of nanoparticles as well as the intra-particle distributions of atoms and metal mixing ratios and to explore the influence of these parameters on the local structure and dynamics in nanoparticles.

  13. Capturing molecular structural dynamics by 100 ps time-resolved X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Tokushi [Department of Materials Science, Tokyo Institute of Technology, 2-12-1-H61 Ohokayama, Meguro-ku, Tokyo 152-8551 (Japan); Non-Equilibrium Dynamics Project, ERATO, Japan Science and Technology Agency, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Nozawa, Shunsuke; Ichiyanagi, Kohei [Non-Equilibrium Dynamics Project, ERATO, Japan Science and Technology Agency, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Tomita, Ayana [Department of Materials Science, Tokyo Institute of Technology, 2-12-1-H61 Ohokayama, Meguro-ku, Tokyo 152-8551 (Japan); Non-Equilibrium Dynamics Project, ERATO, Japan Science and Technology Agency, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Chollet, Matthieu [Department of Materials Science, Tokyo Institute of Technology, 2-12-1-H61 Ohokayama, Meguro-ku, Tokyo 152-8551 (Japan); Ichikawa, Hirohiko [Non-Equilibrium Dynamics Project, ERATO, Japan Science and Technology Agency, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Fujii, Hiroshi [Institute for Molecular Science and Okazaki Institute for Integrative Bioscience, Myodaiji, Okazaki 444-8787 (Japan); Adachi, Shin-ichi [Non-Equilibrium Dynamics Project, ERATO, Japan Science and Technology Agency, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Koshihara, Shin-ya, E-mail: skoshi@cms.titech.ac.jp [Department of Materials Science, Tokyo Institute of Technology, 2-12-1-H61 Ohokayama, Meguro-ku, Tokyo 152-8551 (Japan); Non-Equilibrium Dynamics Project, ERATO, Japan Science and Technology Agency, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Frontier Research Center, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551 (Japan)

    2009-01-01

    An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. The X-ray positional active feedback to crystals in a monochromator combined with a figure-of-merit scan of the laser beam position has been utilized as an essential tool to stabilize the spatial overlap of the X-ray and laser beams at the sample position. As a typical example, a time-resolved XAFS measurement of a photo-induced spin crossover reaction of the tris(1,10-phenanthrorine)iron(II) complex in water is presented.

  14. Picosecond transient absorption spectrometer for dynamic investigation of molecular photophysical processes

    Science.gov (United States)

    Szymanski, M.; Balicki, M.; Pawlowska, E.; Kaczmarek, Franciszek K.; Maciejewski, Anthony A.; Binkowski, M.

    1995-03-01

    A new experimental double beam system for dynamic studies of absorption transitions from initially populated excited states is described. In this system a high power picosecond YAG:Nd3+ laser (Quantel YG 570 C) equipped with generators of second, third, and fourth harmonics serves as an excitation source. The fundamental ((lambda) equals 1064 nm) beam is used for generation of the picosecond continuum which serves as an analyzing light. The temporal relation between incident beams is determined using both variable and fixed delay lines. A M-532.22 translation stage (POLYTEC) is used for micropositioning of a movable cube-corner prism in the optical delay line. A photomultiplier or an OMA detector are applied for measurements of the transient absorption dynamics. A PC 286 microcomputer controls the sequence of operation of all elements of the system and also processes the experimental data. The results of initial tests of this system are presented.

  15. Molecular Dynamics Simulation Studies of Piperazine Activated MDEA Absorption Solution with Methane and Carbon Dioxide

    OpenAIRE

    2010-01-01

    Regenerative chemical absorption process is widely used in industry for removal of carbon dioxide from natural gas, with activated aqueous solutions of alkanolamines considered a beneficial blend. One of the most promising blends is the aqueous mixture of methyldiethanolamine (MDEA) activated by small amount of piperazine, due to the fairly high rate of reaction of piperazine as a cyclic diamine with carbon dioxide and the low heat of regeneration of MDEA as a te...

  16. Towards further understanding of stacking fault tetrahedron absorption and defect-free channels – A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Haidong, E-mail: haidongfan8@foxmail.com [Department of Mechanics, Sichuan University, Chengdu 610065 (China); Key Laboratory of Energy Engineering Safety and Disaster Mechanics, Ministry of Education, Chengdu 610065 (China); Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); El-Awady, Jaafar A. [Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Wang, Qingyuan, E-mail: wangqy@scu.edu.cn [Department of Mechanics, Sichuan University, Chengdu 610065 (China); Key Laboratory of Energy Engineering Safety and Disaster Mechanics, Ministry of Education, Chengdu 610065 (China)

    2015-03-15

    Highlights: • Stacking fault tetrahedron (SFT) is fully absorbed by screw dislocation. • Absorbed SFT becomes moveable with the aid of Lomer dislocations. • Finally SFT is removed from the specimen or from defect-free channels. • Two scenarios responsible for the formation of defect-free channels were proposed. - Abstract: The mechanisms leading to stacking fault tetrahedron (SFT) absorption via interactions with dislocations, and subsequent formation of plastic flow localization in defect-free channels, which were frequently observed in irradiated materials in transmission electron microscopy experiments, are still unclear. To address this, screw dislocation interactions with SFTs in copper were investigated using molecular dynamics (MD) simulations. The interaction details reveal that a screw dislocation can fully absorb an SFT through the thermally activated transformation of Lomer–Cottrell lock into Lomer dislocations. After absorption, almost all the vacancies in the SFT are transferred into Lomer dislocations, which are able to move transversely under complex loading conditions. As a result, SFTs can be removed from the material (for SFTs near surface) or from defect-free channels (for SFTs in the bulk) with the aid of Lomer dislocations. In addition, it was shown that this absorption process is favorable only at high temperature, low applied shear stress and/or high SFT density. These results are in good agreement with in situ TEM observations. The current simulations and analyses provide useful insights into the formation mechanisms of defect-free channels in irradiated materials.

  17. Collision-Induced Infrared Absorption by Molecular Hydrogen Pairs at Thousands of Kelvin

    Directory of Open Access Journals (Sweden)

    Xiaoping Li

    2010-01-01

    Full Text Available Collision-induced absorption by hydrogen and helium in the stellar atmospheres of cool white dwarfs causes the emission spectra to differ significantly from the expected blackbody spectra of the cores. For detailed modeling of radiative processes at temperatures up to 7000 K, the existing H2–H2 induced dipole and potential energy surfaces of high quality must be supplemented by calculations with the H2 bonds stretched or compressed far from the equilibrium length. In this work, we describe new dipole and energy surfaces, based on more than 20 000 ab initio calculations for H2–H2. Our results agree well with previous ab initio work (where those data exist; the calculated rototranslational absorption spectrum at 297.5 K matches experiment similarly well. We further report the calculated absorption spectra of H2–H2 for frequencies from the far infrared to 20 000 cm−1, at temperatures of 600 K, 1000 K, and 2000 K, for which there are no experimental data.

  18. Experimental determination of the lowest excited Xe2 molecular states from VUV absorption spectra

    Science.gov (United States)

    Castex, Marie-Claude

    1981-01-01

    A quantitative analysis of absorption by Xe2 pairs in the wings of the two first resonant lines (1469.6 and 1295.6 Å) is presented as a function of pressure (P<760 Torr) and temperature (130 Kabsorption measurements provide valuable information on the lowest 0u+ and 1u excited states, the 0g+ ground state potential being known from literature. In the near wing region (‖Δν‖<100 cm-1) the shape of the line wings is used as a probe of the asymptotic -2C3/R3-C60/R6 (0u+) and +C3/R3-C61/R6 (1u) potentials assuming at large R a constant oscillator strength, C3 and C6 excited constants are determined. Furthermore the dependence of absorption with temperature is used to derive additional information about the upper states and also to put in evidence some variation of transition moments, at shorter internuclear distances (3.7 Å

  19. Comparison of chromium determination in capsule shells by Zeeman flame and graphite furnace atomic absorption spectrophotometry%塞曼火焰原子吸收与石墨炉原子吸收法测定明胶空心胶囊壳中铬的方法比较

    Institute of Scientific and Technical Information of China (English)

    安代志; 王莉莉; 岳丽君; 戚红卷; 刘雪林

    2012-01-01

    Objective; To investigate effects of Zeeman flame atomic absorption spectrophotometry ( AAS) and graphite furnace AAS on the determination of chromium in capsule shells. Methods; Microwave digestion was adopted to digest the capsule shells. Zeeman effect was used in the background correction. The slit width was set at 1. 3 tun, lamp current 7. 5 mA, and the content of chromium was determined at a wavelength of 359. 3 nm by Zeeman flame AAS and graphite furnace AAS respectively. Results; For the Zeeman flame AAS method, the calibration curve was linear in the range of 0 - 1. 0 μg · mL-1 (r =0. 9998) ,the detection limit was 5. 26 ng · mL-1 ,RSD was 0. 68% - 1. 0% and the average recovery was 100. 0% - 116. 7%. For the graphite furnace AAS method,the calibration curve was linear in the range of 0 - 20 ng · mL -1 ( r = 0. 9999 ) , the detection limit was 0. 26 ng · mL -1, RSD was 1. 7% - 4. 9% and the average recovery was 98. 2% - 105. 6% . Conclusion: The Zeeman flame AAS method is simple, fast, and suitable for the preliminary determination of chromium in capsule shells in emergent cases ; the graphite furnace AAS method is sensitive, accurate, and suitable for the determination of chromium in capsule shells in any case.%目的:研究塞曼效应背景校正的火焰和石墨炉原子吸收法测定胶囊中铬的影响.方法:采用微波消解仪对胶囊壳样品进行消解,在波长359.3 nm下,灯电流7.5 mA;狭缝宽1.3 nm,塞曼背景校正,分别采用塞曼火焰原子吸收和石墨炉原子吸收法进行测定.结果:火焰原子吸收法:线性范围0.04~1.0 mg·mL-1;相关系数为0.9998,检测限5.26 ng· mL-1,RSD为0.68%~1.0%,加样回收率为100.0%~116.7%;石墨炉原子吸收法:线性范围为1~20 ng· mL-1,相关系数为0.9998,检测限为0.26 ng·mL-1,RSD为1.7%~4.9%,加样回收率为98.2% ~ 105.6%.结论:塞曼火焰原子吸收法简便、快捷,能满足大量样品筛选及企业内部质控筛选与

  20. Determination of trace concentrations of chlorine in aqueous solutions by high-resolution continuum source graphite furnace molecular absorption spectrometry

    Science.gov (United States)

    Machyňák, Ľubomír; Čacho, František; Němeček, Martin; Beinrohr, Ernest

    2016-11-01

    Trace concentrations of total chlorine were determined by means of molecular absorption of indium mono-chloride (InCl) at 267.217 nm using high-resolution continuum source graphite furnace molecular absorption spectrometry. The effects of chemical modifiers and the amount of In on the sensitivity and accuracy were investigated. The optimum pyrolysis and vaporization temperatures were 600 °C and 1400 °C, respectively. The limit of detection and characteristic mass were found to be 0.10 ng and 0.21 ng, respectively. Potential non-spectral and spectral interferences were tested for various metals and non-metals at concentrations up to 50 mg L- 1 and for phosphoric, sulphuric and nitric acids. No spectral interferences were observed. Significant non-spectral interferences were observed with F, Br, and I at concentrations higher than 1 mg L- 1, 5 mg L- 1 and 25 mg L- 1, respectively, which is probably caused by formation of competitive indium halogen molecules. Higher concentrations of mineral acids depressed the signal owing to the formation of volatile HCl. The calibration curve was linear in the range between 0.3 and 10 ng with a correlation coefficient of R = 0.993. The elaborated method was used for the chlorine determination in various waters and a drug sample.

  1. Determination of sulfur in coal and ash slurry by high-resolution continuum source electrothermal molecular absorption spectrometry

    Science.gov (United States)

    Nakadi, Flávio V.; Rosa, Lilian R.; da Veiga, Márcia A. M. S.

    2013-10-01

    We propose a procedure for the determination of sulfur in coal slurries by high resolution continuum source electrothermal molecular absorption spectrometry. The slurry, whose concentration is 1 mg mL- 1, was prepared by mixing 50 mg of the sample with 5% v/v nitric acid and 0.04% m/v Triton X-100 and was homogenized manually. It sustained good stability. The determination was performed via CS molecular absorption at 257.592 nm, and the optimized vaporization temperature was 2500 °C. The accuracy of the method was ensured by analysis of certified reference materials SRM 1632b (trace elements in coal) and SRM 1633b (coal fly ash) from the National Institute of Standards and Technology, using external calibration with aqueous standards prepared in the same medium and used as slurry. We achieved good agreement with the certified reference materials within 95% confidence interval, LOD of 0.01% w/w, and RSD of 6%, which confirms the potential of the proposed method.

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

    Science.gov (United States)

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

    1976-01-01

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

  3. Surface composition of Mercury from reflectance spectrophotometry

    Science.gov (United States)

    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.

  4. Electronic absorption spectra and nonlinear optical properties of CO2 molecular aggregates: A quantum chemical study

    Indian Academy of Sciences (India)

    Tarun K Mandal; Sudipta Dutta; Swapan K Pati

    2009-09-01

    We have investigated the structural aspects of several carbon dioxide molecular aggregates and their spectroscopic and nonlinear optical properties within the quantum chemical theory framework. We find that, although the single carbon dioxide molecule prefers to be in a linear geometry, the puckering of angles occur in oligomers because of the intermolecular interactions. The resulting dipole moments reflect in the electronic excitation spectra of the molecular assemblies. The observation of significant nonlinear optical properties suggests the potential application of the dense carbon dioxide phases in opto-electronic devices.

  5. Molecular pathways of cholesterol absorption regulation%调控胆固醇吸收的分子通路

    Institute of Scientific and Technical Information of China (English)

    邵翅; 杨林

    2015-01-01

    Cholesterol imbalance can cause a variety of diseases,such as high cholesterol,cardiovascular disease, while the cholesterol balance in body is maintained by synthesis, absorption, metabolism and circulation of cholesterol,and the absorption of cholesterol is a crucial step. Cholesterol absorption occurs mainly in the small intestine and proximal jejunum, and it is regulated by a number of proteins. Niemann⁃Pick C1⁃like 1 protein (NPC1L1) is responsible for the cholesterol uptake.ATP-binding cassette(ABC) G5/G8 inhibits the absorption of cholesterol. Acyl⁃coenzyme A( CoA):cholesterol acyltransferase( ACAT) catalyzes the cholesterol esterified reaction for raising cholesterol absorption.ATP⁃binding cassette transporters A1(ABCA1) transports cholesterol in peripheral tissues and these proteins are also affected by other regulatory factors. Parsing cholesterol absorption of molecular pathways has major directive significance the prevention and treatment of diseases related with cholesterol imbalance.Therefore, the molecular pathways of cholesterol absorption regulation were reviewed in this paper.%机体内的胆固醇失衡会引发多种疾病,如高胆固醇血症、心脑血管疾病等,而其平衡由胆固醇的合成、吸收、代谢和循环共同维持,其中胆固醇的吸收至关重要。胆固醇的吸收主要发生在小肠和近段空肠,受众多蛋白的调控。尼曼-匹克C1样蛋白1( NPC1L1)负责胆固醇的摄取;ATP 结合盒转运蛋白( ABCG5/ABCG8)则抑制胆固醇的吸收,酰基辅酶A-胆固醇酰基转移酶( ACAT)催化胆固醇脂化提高胆固醇吸收;ATP 结合盒转运蛋白A1( ABCA1)负责外周组织胆固醇的转运,而这些蛋白又受到其他调控因子的影响。解析胆固醇吸收的分子通路对胆固醇失衡相关疾病的预防及治疗具有重大指导意义。因此,本文就调控胆固醇吸收的分子通路进行综述。

  6. Photodissociation Exploration for Near-Visible UV Absorption of Molecular Bromine

    Institute of Scientific and Technical Information of China (English)

    Dong-fang Zhang; Bing Zhang

    2008-01-01

    The photodissociation of Br2 was investigated within the near-visible UV absorption band.Based on the potential curves for the ground and low-lying excited states,the optical cross-sections for the discrete transitions of C1∏u,B3+∏+0u,A3∏1u←X1∑+g and their total energy absorption spectrum are derived,and the quantum yield of(Br+Br*) channel are determined correspondingly.The one-dimensional Landau-Zener model is used to evaluate the behavior of curve crossing during photodissociation.The results indicate that the influence of nonadiabatic mechanism,which may be caused by the electronic-vibrational interplay between the B and C states,is negligibly small for the(Br+Br*) channel.From the Landau-Zener modeling of the observed product recoil parameter β(Br+Br),the best-fit value of the coupling matrix element or coupling strength between the diabatic B and C state potentials is obtained.

  7. Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption.

    Science.gov (United States)

    Li, Yongfang

    2012-05-15

    Bulk heterojunction (BHJ) polymer solar cells (PSCs) sandwich a blend layer of conjugated polymer donor and fullerene derivative acceptor between a transparent ITO positive electrode and a low work function metal negative electrode. In comparison with traditional inorganic semiconductor solar cells, PSCs offer a simpler device structure, easier fabrication, lower cost, and lighter weight, and these structures can be fabricated into flexible devices. But currently the power conversion efficiency (PCE) of the PSCs is not sufficient for future commercialization. The polymer donors and fullerene derivative acceptors are the key photovoltaic materials that will need to be optimized for high-performance PSCs. In this Account, I discuss the basic requirements and scientific issues in the molecular design of high efficiency photovoltaic molecules. I also summarize recent progress in electronic energy level engineering and absorption spectral broadening of the donor and acceptor photovoltaic materials by my research group and others. For high-efficiency conjugated polymer donors, key requirements are a narrower energy bandgap (E(g)) and broad absorption, relatively lower-lying HOMO (the highest occupied molecular orbital) level, and higher hole mobility. There are three strategies to meet these requirements: D-A copolymerization for narrower E(g) and lower-lying HOMO, substitution with electron-withdrawing groups for lower-lying HOMO, and two-dimensional conjugation for broad absorption and higher hole mobility. Moreover, better main chain planarity and less side chain steric hindrance could strengthen π-π stacking and increase hole mobility. Furthermore, the molecular weight of the polymers also influences their photovoltaic performance. To produce high efficiency photovoltaic polymers, researchers should attempt to increase molecular weight while maintaining solubility. High-efficiency D-A copolymers have been obtained by using benzodithiophene (BDT), dithienosilole

  8. 微波消解/AAS法测定分子筛中的镍含量%Determination of nickel in molecular sieve catalyst by microwave digestion-atomic absorption spectrometry

    Institute of Scientific and Technical Information of China (English)

    陈震; 贾隽涵; 王宸宸; 王永娟; 易玉峰; 丁福臣

    2016-01-01

    分子筛催化剂以及含有金属钨的催化剂在一般的微波消解体系下难以被消解。探索了以浓HCl、浓HCl+H2 O2、浓HNO3+H2 O2、王水、浓H2 SO4+H2 O2、浓H2 SO4+浓HNO3、浓H3 PO4为消解体系,消解含金属钨的分子筛催化剂。找到了一种能在短时间内既能消解分子筛催化剂又可以消解含金属钨的浓H3 PO4消解体系。并通过原子吸收光谱法和分光光度法对催化剂中的镍含量进行了测量。该方法样品用量少、省时、省酸、操作简单、环境污染小。%Molecular sieve catalysts and catalysts containing tungsten are difficult to be dissolved by mi -crowave in routine acidic digestion system .Acidic digestion system of concentrated hydrochloric acid ,con-centrated hydrochloric acid and hydrogen peroxide mixture ,concentrated nitric acid and hydrogen perox-ide mixture,nitrohydrochloric acid,concentrated sulphuric acid and hydrogen peroxide mixture ,concen-trated sulphuric acid and concentrated nitric acid mixture ,concentrated phosphoric acid were used to dis-solve molecular sieve catalysts containing tungsten by microwave .Concentrated phosphoric acid was found to be the suitable digestion system to dissolve the molecular sieve catalyst containing tungsten in a short period of time .The nickel content in the catalyst was measured by atomic absorption spectrometry and spectrophotometry.The method has the advantage of less sample needed ,high-speed,less acid needed, simplicity of operation and little of environmental pollution .

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

    Science.gov (United States)

    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.

  10. STUDY ON THE DETERMINATION OF TRACE Fe(Ⅲ) BY THIN LAYER RESIN PHASE SPECTROPHOTOMETRY

    Institute of Scientific and Technical Information of China (English)

    HOU Yanmin; YANG Yongsheng; XIE Jimin; HUANG Weihong

    2007-01-01

    A method to determine Fe(Ⅲ) by thin layer resin phase spectrophotometry has been developed in this paper. The colored complex formed by Fe(Ⅲ) and 1,2-benzendiol is concentrated on the 717# resin, then Fe(Ⅲ) can be determined directly by making thin layer. The method is sensitive with a apparent molar absorption of 4.8×104L/mol. cm, which is 16 times higher than that of liquid phase spectrophotometry, most coexisting ions do not influence the determination. The detection limit for Fe(Ⅲ) is 1.47μg/L with the precision of 3.3% [n=6, 7μg/50mL Fe(Ⅲ)]. The calibration curve is linear in the range of 0~25μg/50mL. The preposed method was applied to the determination of Fe(Ⅲ) in water sample with satisfactory results.

  11. STUDY ON THE DETERMINATION OF TRACE Fe(Ⅲ) BY THIN LAYER RESIN PHASE SPECTROPHOTOMETRY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A method to determine Fe(Ⅲ) by thin layer resin phase spectrophotometry has been developed in this paper. The colored complex formed by Fe(Ⅲ) and 1,2-benzendiol is concentrated on the 717# resin, then Fe(Ⅲ) can be determined directly by making thin layer. The method is sensitive with a apparent molar absorption of 4.8×104L/mol·cm, which is 16 times higher than that of liquid phase spectrophotometry, most coexisting ions do not influence the determination. The detection limit for Fe(Ⅲ) is 1.47μg/L with the precision of 3.3% [n=6, 7μg/50mL Fe(Ⅲ)]. The calibration curve is linear in the range of 0~25μg/50mL. The preposed method was applied to the determination of Fe(Ⅲ) in water sample with satisfactory results.

  12. Optical Absorption in Molecular Crystals from Time-Dependent Density Functional Theory

    Science.gov (United States)

    2017-04-23

    quantitatively and non-empirically within the framework of time-dependent density functional theory (TDDFT), using the recently-developed optimally-tuned...showing that fundamental gaps and optical spectra of molecular solids can be predicted quantitatively and non-empirically within the framework of...II. THEORETICAL AND COMPUTATIONAL APPROACH A. Optimally-tuned range-separated hybrid functionals In the range-separated hybrid (RSH) method, the

  13. Molecular dynamics and a spectroscopic study of sulfur dioxide absorption by an ionic liquid and its mixtures with PEO.

    Science.gov (United States)

    Hoher, Karina; Cardoso, Piercarlo F; Lepre, Luiz F; Ando, Rômulo A; Siqueira, Leonardo J A

    2016-10-19

    An investigation comprising experimental techniques (absorption capacity of SO2 and vibrational spectroscopy) and molecular simulations (thermodynamics, structure, and dynamics) has been performed for the polymer poly(ethylene oxide) (PEO), the ionic liquid butyltrimethylammonium bis(trifluoromethylsulfonyl)imide ([N4111][Tf2N]) and their mixtures as sulfur dioxide (SO2) absorbing materials. The polymer PEO has higher capacity to absorb SO2 than the neat ionic liquid, whereas the mixtures presented intermediary absorption capacities. The band assigned to the symmetric stretching band of SO2 at ca. 1140 cm(-1), which is considered a spectroscopic probe for the strength of SO2 interactions with its neighborhood, shifts to lower wavenumbers as more negative total interaction energy values of SO2 were evaluated from the simulations. The solvation free energy of SO2, ΔGsol, correlates linearly with the absorption capacity of SO2. The negative values of ΔGsol are due to negative and positive values of enthalpy and entropy, respectively. In the ionic liquid, SO2 weakens the cation-anion interactions, whereas in the mixture with a high content of PEO these interactions are slightly increased. Such effects were correlated with the relative population of cisoid and transoid conformers of Tf2N anions as revealed by Raman spectroscopy. Moreover, the presence of SO2 in the systems provokes the increase of diffusion coefficients of the absorbing species in comparison with the systems without the gas. Proper to the slow dynamics of the polymer, the diffusion coefficient of ions and SO2 diminishes with the increase of the PEO content.

  14. Self-corrected sensors based on atomic absorption spectroscopy for atom flux measurements in molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Du, Y., E-mail: yingge.du@pnnl.gov, E-mail: scott.chambers@pnnl.gov; Liyu, A. V. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Droubay, T. C.; Chambers, S. A., E-mail: yingge.du@pnnl.gov, E-mail: scott.chambers@pnnl.gov [Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Li, G. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    2014-04-21

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device detector in a double-beam configuration, we employ either a non-resonant line or a resonant line with low cross section from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

  15. Self-corrected Sensors Based On Atomic Absorption Spectroscopy For Atom Flux Measurements In Molecular Beam Epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Du, Yingge; Droubay, Timothy C.; Liyu, Andrey V.; Li, Guosheng; Chambers, Scott A.

    2014-04-24

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device (CCD) detector in a double-beam configuration, we employ a non-resonant line or a resonant line with lower absorbance from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

  16. Self-corrected sensors based on atomic absorption spectroscopy for atom flux measurements in molecular beam epitaxy

    Science.gov (United States)

    Du, Y.; Droubay, T. C.; Liyu, A. V.; Li, G.; Chambers, S. A.

    2014-04-01

    A high sensitivity atom flux sensor based on atomic absorption spectroscopy has been designed and implemented to control electron beam evaporators and effusion cells in a molecular beam epitaxy system. Using a high-resolution spectrometer and a two-dimensional charge coupled device detector in a double-beam configuration, we employ either a non-resonant line or a resonant line with low cross section from the same hollow cathode lamp as the reference for nearly perfect background correction and baseline drift removal. This setup also significantly shortens the warm-up time needed compared to other sensor technologies and drastically reduces the noise coming from the surrounding environment. In addition, the high-resolution spectrometer allows the most sensitive resonant line to be isolated and used to provide excellent signal-to-noise ratio.

  17. A Comparative Study of Molecular Structure, pKa, Lipophilicity, Solubility, Absorption and Polar Surface Area of Some Antiplatelet Drugs

    Directory of Open Access Journals (Sweden)

    Milan Remko

    2016-03-01

    Full Text Available Theoretical chemistry methods have been used to study the molecular properties of antiplatelet agents (ticlopidine, clopidogrel, prasugrel, elinogrel, ticagrelor and cangrelor and several thiol-containing active metabolites. The geometries and energies of most stable conformers of these drugs have been computed at the Becke3LYP/6-311++G(d,p level of density functional theory. Computed dissociation constants show that the active metabolites of prodrugs (ticlopidine, clopidogrel and prasugrel and drugs elinogrel and cangrelor are completely ionized at pH 7.4. Both ticagrelor and its active metabolite are present at pH = 7.4 in neutral undissociated form. The thienopyridine prodrugs ticlopidine, clopidogrel and prasugrel are lipophilic and insoluble in water. Their lipophilicity is very high (about 2.5–3.5 logP values. The polar surface area, with regard to the structurally-heterogeneous character of these antiplatelet drugs, is from very large interval of values of 3–255 Å2. Thienopyridine prodrugs, like ticlopidine, clopidogrel and prasugrel, with the lowest polar surface area (PSA values, exhibit the largest absorption. A high value of polar surface area (PSA of cangrelor (255 Å2 results in substantial worsening of the absorption in comparison with thienopyridine drugs.

  18. Determination of total sulfur in food samples by solid sampling high-resolution continuum source graphite furnace molecular absorption spectrometry.

    Science.gov (United States)

    Ozbek, Nil; Akman, Suleyman

    2013-05-22

    The determination of sulfur in food samples via the rotational molecular absorption of carbon monosulfide (CS) was performed using a solid sampling high-resolution continuum source electrothermal atomic absorption spectrophotometer (SS-HR-CS-ETAAS). In the presence of plenty of carbon in the graphite furnace as well as in food samples, CS was formed in the gas phase without the addition of any molecule forming element externally. The effects of the wavelength selected to detect CS, graphite furnace program, amount of sample, coating of the graphite tube and platform with Ir, and the use of a Pd modifier on the accuracy, precision, and sensitivity were investigated and optimized. Sulfur was determined in an iridium-coated graphite tube/platform at 258.056 nm by applying a pyrolysis temperature of 1000 °C and a molecule forming temperature of 2400 °C. The calibration curve prepared from Na2S was linear between 0.01 μg (LOQ) and 10 μg of S. The accuracy of the method was tested by analyzing certified reference spinach and milk powder samples by applying a linear calibration technique prepared from aqueous standard. The results were in good agreement with certified values. The limit of detection and characteristic mass of the method were 3.5 and 8.1 ng of S, respectively. By applying the optimized parameters, the concentrations of S in onion and garlic samples were determined.

  19. Changing of Bacteria Catalase Activity Under the Influence of Electro-Magnetic Radiation on a Frequency of Nitric Oxide Absorption and Radiation Molecular Spectrum

    Directory of Open Access Journals (Sweden)

    G.M. Shub

    2009-09-01

    Full Text Available The dynamics of catalase activity degree changing in Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa is described under the influence of electro-magnetic radiation on a frequency of nitric oxide absorption and radiation molecular spectrum. The panoramic spectrometric measuring complex, developed in Central Scientific Research Institute of measuring equipment Public corporation, Saratov, was used while carrying out the research. Electromagnetic vibrations of extremely high frequencies were stimulated in this complex imitating the structure of nitric oxide absorption and radiation molecular spectrum. The growth of activity of the mentioned enzyme of the strains under research was detected. The most significant changes were observed under 60-minutes exposure.

  20. DETECTION OF MOLECULAR ABSORPTION IN THE DAYSIDE OF EXOPLANET 51 PEGASI b?

    Energy Technology Data Exchange (ETDEWEB)

    Brogi, M.; Snellen, I. A. G.; Birkby, J. L. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); De Kok, R. J. [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Albrecht, S. [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); De Mooij, E. J. W., E-mail: brogi@strw.leidenuniv.nl [Department of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, ON M5S 3H4 (Canada)

    2013-04-10

    In this paper, we present ground-based high-resolution spectroscopy of 51 Pegasi using CRIRES at the Very Large Telescope. The system was observed for 3 Multiplication-Sign 5 hr at 2.3 {mu}m at a spectral resolution of R = 100,000, targeting potential signatures from carbon monoxide, water vapor, and methane in the planet's dayside spectrum. In the first 2 Multiplication-Sign 5 hr of data, we find a combined signal from carbon monoxide and water in absorption at a formal 5.9{sigma} confidence level, indicating a non-inverted atmosphere. We derive a planet mass of M{sub P} = (0.46 {+-} 0.02)M{sub Jup} and an orbital inclination i between 79. Degree-Sign 6 and 82. Degree-Sign 2, with the upper limit set by the non-detection of the planet transit in previous photometric monitoring. However, there is no trace of the signal in the final five hours of data. A statistical analysis indicates that the signal from the first two nights is robust, but we find no compelling explanation for its absence in the final night. The latter suffers from stronger noise residuals and greater instrumental instability than the first two nights, but these cannot fully account for the missing signal. It is possible that the integrated dayside emission from 51 Peg b is instead strongly affected by weather. However, more data are required before we can claim any time variability in the planet's atmosphere.

  1. Integração de técnicas analíticas e proposta de experimentos para cursos de graduação em análise instrumental: uso de espectrômetro de absorção atômica para medidas de absorção molecular Integration of analytical techniques and undergraduate laboratory in instrumental analysis: use of an atomic absorption spectrometer for molecular absorption measurements

    Directory of Open Access Journals (Sweden)

    Marcos S. Gomes

    2006-07-01

    Full Text Available Simple experiments are proposed for measuring molecular absorption of chromate and dichromate ions using an atomic absorption spectrometer. The experiments can help undergraduate students in instrumental analysis courses understand important aspects involving conceptual and instrumental similarities and differences between frequently used analytical techniques. Hollow cathode lamps were selected with wavelengths in the region of molecular absorption of chromate and dichromate. Calibration curves were obtained and the linear dynamic range was evaluated. Results were compared with those obtained in a molecular absorption spectrometer. The molar absorptivities obtained were also compared.

  2. Radioprotective Action of Low-Intensity Light into the Red Absorption Band of Endogenous Molecular Oxygen

    Science.gov (United States)

    Ivanov, A. V.; Mashalov, A. A.; Zakharov, S. D.

    2016-08-01

    Application of ionizing radiation in oncology (radiation therapy) is a widespread way to eliminate malignant tumors. Normal tissues are inevitable included in any radiation field, and their reliable protection is actual till now. All attempts to solve the problem are based on search of effective radioprotectors, i.e. chemical compounds of various classes, which should be entered into the patient. To date about 50,000 compounds with some radioprotection properties had been tested, but the most effective of them have been simultaneously the most toxic. Here the preliminary results of researches devoted to development of an optical technique on basis of the light-oxygen effect for the protection of women with breast cancer from side effects of the radiation therapy are presented. A low intensity emission of the semiconductor laser in a red spectral interval was used to excite a very small quantity of endogenous molecular oxygen in O2(1Δg) state. It is shown, that application of the method at occurrence of earliest signs of radiation injury allows notably reducing dangerous breaks in radiation therapy course.

  3. Molecular phonons and their absorption/emission spectra from the far IR to microwaves

    CERN Document Server

    Papoular, Renaud

    2015-01-01

    Together with their fingerprint modes, molecules carry coherent vibrations of all their atoms (phonons). Phonon spectra extend from $\\sim$20 to more than $10^{4}\\,\\mu$m, depending on molecular size. These spectra are discrete but large assemblies of molecules of the same family, differing only by minor structural details, will produce continua. As such assemblies are expected to exist in regions where dust accumulates, they are bound to contribute to the observed continua underlying the Unidentified Infrared Bands and the 21-mum band of planetary nebulae as well as to the diffuse galactic emission surveyed by the Planck astronomical satellite and other means. The purpose of this work is to determine, for carbon-rich molecules, the intensity of such continua and their extent into the millimetric range, and to evaluate their detectability in this range. The rules governing the spectral distributions of phonons are derived and shown to differ from those which obtain in the solid state. Their application allow th...

  4. Micro-lightguide spectrophotometry for tissue perfusion in ischemic limbs

    DEFF Research Database (Denmark)

    Jørgensen, Lise Pyndt; Schroeder, Torben V

    2012-01-01

    To validate micro-lightguide spectrophotometry (O2C) in patients with lower limb ischemia and to compare results with those obtained from toe blood pressure.......To validate micro-lightguide spectrophotometry (O2C) in patients with lower limb ischemia and to compare results with those obtained from toe blood pressure....

  5. HST/COS Spectra of DF Tau and V4046 SGR: First Detection of Molecular Hydrogen Absorption Against the Ly$\\alpha$ Emission Line

    CERN Document Server

    Yang, Hao; France, Kevin

    2011-01-01

    We report the first detection of molecular hydrogen (H$_{2}$) absorption in the Lyman-$\\alpha$ emission line profiles of two classical T Tauri stars (CTTSs), DF Tau and V4046 Sgr, observed by \\emph{HST}/COS. This absorption is the energy source for many of the Lyman-band H$_{2}$ fluorescent lines commonly seen in the far-ultraviolet spectra of CTTSs. We find that the absorbed energy in the H$_{2}$ pumping transitions from a portion of the Lyman-$\\alpha$ line significantly differ from the amount of energy in the resulting fluorescent emission. By assuming additional absorption in the H I Lyman-$\\alpha$ profile along our light of sight, we can correct the H$_{2}$ absorption/emission ratios so that they are close to unity. The required H I absorption for DF Tau is at a velocity close to the radial velocity of the star, consistent with H I absorption in the edge-on disk and interstellar medium. For V4046 Sgr, a nearly face-on system, the required absorption is between +100 km/s and +290 km/s, most likely resultin...

  6. Disorder-induced enhancement of indirect absorption in a GeSn photodetector grown by molecular beam epitaxy

    Science.gov (United States)

    Li, H.; Chang, C.; Cheng, H. H.; Sun, G.; Soref, R. A.

    2016-05-01

    We report an investigation on the absorption mechanism of a GeSn photodetector with 2.4% Sn composition in the active region. Responsivity is measured and absorption coefficient is calculated. Square root of absorption coefficient linearly depends on photon energy indicating an indirect transition. However, the absorption coefficient is found to be at least one order of magnitude higher than that of most other indirect materials, suggesting that the indirect optical absorption transition cannot be assisted only by phonon. Our analysis of absorption measurements by other groups on the same material system showed the values of absorption coefficient on the same order of magnitude. Our study reveals that the strong enhancement of absorption for the indirect optical transition is the result of alloy disorder from the incorporation of the much larger Sn atoms into the Ge lattice that are randomly distributed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Marcialis, R.L.; Lebofsky, L.A. (JPL, Pasadena, CA (USA) Arizona Univ., Tucson (USA))

    1991-02-01

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

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

    Science.gov (United States)

    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.

  9. The Simultaneous Determination of Five Components Including Acetaminophen by Ridge Regression Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ridge regression spectrophotometry (LHG) is used for the simultaneous determination of five components (acetaminophen, p-aminophenol, caffeine, chlorphenamine maleate and guaifenesin) in cough syrup. The computer program of LHG is based on VB language.The difficulties in overlapping of absorption spectrums of five compounds are overcome by this procedure. The experimental results show that the average recovery of each component is in the range from 97.9% to 103.3% and each component obtains satisfactory results without any pre-separation.

  10. Electronic absorption spectra of pyridine and nicotine in aqueous solution with a combined molecular dynamics and polarizable QM/MM approach.

    Science.gov (United States)

    Pagliai, Marco; Mancini, Giordano; Carnimeo, Ivan; De Mitri, Nicola; Barone, Vincenzo

    2017-03-05

    The electronic absorption spectra of pyridine and nicotine in aqueous solution have been computed using a multistep approach. The computational protocol consists in studying the solute solvation with accurate molecular dynamics simulations, characterizing the hydrogen bond interactions, and calculating electronic transitions for a series of configurations extracted from the molecular dynamics trajectories with a polarizable QM/MM scheme based on the fluctuating charge model. Molecular dynamics simulations and electronic transition calculations have been performed on both pyridine and nicotine. Furthermore, the contributions of solute vibrational effect on electronic absorption spectra have been taken into account in the so called vertical gradient approximation. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.

  11. The characterization of low energy molecular hydrogen ion—induced defects in synthetic diamond by optical absorption

    Institute of Scientific and Technical Information of China (English)

    MaZhong-Quan; AokiY; 等

    1998-01-01

    The results of optical absorption analysis of the synthetic diamonds(type Ib) which were implanted with 40 keV molecular hydrogen ions at doses of 1015-1017H/cm2(at 100K),showed that the increase of optical density(OD) of modified layer(-140nm) in UV-VIS region was dependent upon the damage level caused by ion implantation process.The range of relative optical band gap(Er.opt) around 2.0eV suggested that an amorphous carbon network structure like a-C film,which probably contains some localized subtetrabedral-coordinated clusters embedded in the fourflod(sp3) sites.was tentatively found in this layer,basing on the optical gap of carbon materials.The evolution of Er,opt with ion fluence indicated that no more hydrogenated carbon compositions were produced in as -implanted samples,while the increase of Er,opt with annealing temperature was very similar to that of hydrogen content dependence of Eopt in hydrogenately amorphous carbon(a-C:H):In addition the optical inhomogeneity of type Ib diamond has been revealed by a 2-dimension topograph in transmission mode at λ=430nm。

  12. Effects of nitrogen composition on fermentation performance of brewer's yeast and the absorption of peptides with different molecular weights.

    Science.gov (United States)

    Mo, Fen; Zhao, Haifeng; Lei, Hongjie; Zhao, Mouming

    2013-11-01

    Four kinds of worts with different nitrogen compositions were used to examine their effects on fermentation performance of brewer's yeast. The absorption pattern of peptides with different molecular weights (Mw) in yeast cells during wort fermentation was also investigated. Results showed that both the nitrogen composition and level had significant impacts on the yeast biomass accumulation, ethanol production, and free amino nitrogen and sugars consumption rates. Worts supplemented with wheat gluten hydrolysates increased 11.5% of the biomass, 5.9% of fermentability, and 0.6% of ethanol content and decreased 25.6% of residual sugar content during wort fermentation. Moreover, yeast cells assimilated peptides with various Mw differently during fermentation. Peptides with Mw below 1 kDa decreased quickly, and the rate of assimilation was more than 50% at the end of fermentation, while those with Mw above 10 kDa almost could not be assimilated by yeast. All these results further indicated that the level and composition of wort nitrogen had significant impacts on the growth and fermentation performances of brewer's yeast, and peptides with Mw below 1 kDa were one of preferred nitrogen sources for brewer's yeast.

  13. Optical imagery and spectrophotometry of CTB 80

    Science.gov (United States)

    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.

  14. Spectrophotometry of the shell around AG Carinae

    Science.gov (United States)

    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.

  15. OH concentration in an atmospheric-pressure methane-air flame from molecular-beam mass spectrometry and laser-absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cattolica, R.J.; Yoon, S.; Knuth, E.L.

    1980-12-01

    The concentration of the OH radical in a stoichiometric methane-air flat flame at atmospheric pressure was measured with both laser-absorption spectroscopy and molecular-beam mass spectrometry (MBMS). The nonequilibrium peak OH concentrations and the OH decay rate measured from the two techniques were in good agreement. The OH profile from the MBMS measurements, however, was shifted downstream from the absorption measurements by approximately 5 times the sampling-orifice diameter. A comparison of temperature profiles from thermocouple measurements and from a molecular-beam time-of-flight technique exhibited a similar downstream shift. The MBMS measurements effectively sampled the gas properties approximately five orifice diameters ahead of the sampling-probe tip. Perturbation of the OH concentration profile using various sampling probes indicate the importance of minimizing the length of the sampling-orifice channel to reduce composition relaxation during sampling.

  16. Near-infrared spectrophotometry of Titan

    Science.gov (United States)

    Trafton, L. M.

    1975-01-01

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

  17. Determination of guaiphenesin in anti-tussive pharmaceutical preparations containing dextromethorphan by first- and second-derivative ultraviolet spectrophotometry.

    Science.gov (United States)

    Lee, A R; Hu, T M

    1994-06-01

    Rapid, simple and direct assay procedures based on selective first (D1)- and second (D2)-derivative spectrophotometry, using a zero-crossing technique of measurement at 279.2 and 280.0 nm, respectively, have been developed for the specific determination of guaiphenesin in the presence of dextromethorphan, drugs with closely overlapping absorption spectra, in synthetic admixtures and in pharmaceutical dosage forms (tablets and syrups). The methods do not require extraction with organic solvents and are easier to perform than their conventional counterparts. Calibration graphs were linear (r = 0.99999 for D1 and 0.99969 for D2, respectively). Good selectivity, accuracy and precision were found. However, the performance of the analysis of guaiphenesin by the second-derivative mode deteriorated when the ratio of dextromethorphan to guaiphenesin was greater than one. Thus, the first-derivative spectrophotometry is the method of choice for the assay of tablets and syrups containing the two drugs.

  18. STUDY ON THE DETERMINATION OF TRACE BISMUTH(Ⅲ) BY THIN-LAYER RESIN PHASE SPECTROPHOTOMETRY

    Institute of Scientific and Technical Information of China (English)

    YAN Yongsheng; LU Xiaohua; FU Chengguang

    2003-01-01

    In this paper, a new thin-layer ion-exchange resin phase analytical method is introduced. It is based on that, the bismuthous cation can associate with iodic anions, so as to formed an anioncomplex [BiI-4] in a strong acidic environments. This anion complex can also exchanges with a weaker anions on the surface active site of anion exchange resin, so that a [R+] [BiI-4] solid phase binary associational system is produced. Owing to the solid system is a great many dispersive particulates, it can be pressed to a thin-layer by press tools of the so called "thin-layer resin phase"or "resin phase ", and using this solid association system spectrophotometry for the determination of trace metals. So it can increase the analytical sensitivity. This association system exhibits maximum absorbance at 460nm, and obeys Beer's law over the concentration range 0. 01ug/ml~1.20ug/ml of bismuthous(Ⅲ). It has a molar absorptivity of 7.1 ×105 [L/mol cm]. It indicated the resin phase spectrophotometry is a sensitive analytical method for trace bismuthous. It is 18 times higher than routine aqueous spectrophotometry. The relative standard deviations is 1.82% (n=6) for the measurements of 0. 5ug/ml Bi(Ⅲ). The detection limit of Bismuthous(Ⅲ) is 1.4 ×10-8mol/L. The method has applied to the analysis Bi(Ⅲ) in environmental water samples.

  19. Direct Computation on the Kinetic Spectrophotometry

    DEFF Research Database (Denmark)

    Hansen, Jørgen-Walther; Broen Pedersen, P.

    1974-01-01

    This report describes an analog computer designed for calculations of transient absorption from photographed recordings of the oscilloscope trace of the transmitted light intensity. The computer calculates the optical density OD, the natural logarithm of OD, and the natural logarithm of the diffe...

  20. Airborne infrared spectrophotometry of Mira variables

    Science.gov (United States)

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

    1978-01-01

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

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

    Science.gov (United States)

    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.

  2. Spectrophotometry of Kuiper Belt Objects and Centaurs

    Science.gov (United States)

    Lederer, S. M.; Vilas, F.

    2002-09-01

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

  3. VALIDATION OF CYCLAMATE ANALYSIS METHOD WITH SPECTROPHOTOMETRY AND TURBIDIMETRY

    Directory of Open Access Journals (Sweden)

    Regina Tutik Padmaningrum

    2016-04-01

    Full Text Available This research aims to validate methods of analysis by spectrophotometry and turbidimetry cyclamate in the sample drink mango-flavored jelly drink  by spectrophotometry with hypochlorite reagent, ultraviolet spectrophotometry (without reagent and turbidimetry. The object of research was the validity parameters spectrophotometric method were linearity, linear range, the limit of detection, limit of quantitation, precision, and accuracy. The calibration curve of standard solution of sodium cyclamate in the spectrophotometric method with hypochlorite reagent, UV spectrophotometry (without reagent, and turbidimetry are linear. Linear range each method respectively at a concentration were (211.36-747.08; (16.000-146.434; and (1.8521-6.1717 ppm. The detection limit of each method successively were 53.6028; 0.5833; and 0.2723 ppm. Limit of quantitation each method successively were 66.9948; 1.9443; and 0.8068 ppm. Spectrophotometric analysis method cyclamate with hypochlorite reagent had good precision and accuracy. Ultra violet  spectrophotometric analysis method of cyclamate have a good precision but the accuracy was not good. Turbidimetric methods  analysis of cyclamate had  precision and accuracy were not good. Keywords:   method validation, spectrophotometry, turbidimetry, cyclamate

  4. The Radio to Infrared Emission of Very High Redshift Gamma-Ray Bursts: Probing Early Star Formation through Molecular and Atomic Absorption Lines

    CERN Document Server

    Inoue, S; Ciardi, B; Inoue, Susumu; Omukai, Kazuyuki; Ciardi, Benedetta

    2005-01-01

    We evaluate the broadband afterglow emission of very high redshift gamma-ray bursts (GRBs) using standard relativistic blastwave models with both forward and reverse shock components. For a broad range of parameters, a generic property for GRBs at redshifts $z \\sim$ 5--30 is that the emission peaks in the millimeter to far-infrared bands with milli-Jansky flux levels, first at a few hours after the burst due to the reverse shock, and then again for several days afterwards with somewhat lower flux due to the forward shock. The radio, submillimeter and infrared continuum emission should be readily detectable out to $z \\ga 30$ by the Atacama Large Millimeter Array (ALMA), Extended Very Large Array (EVLA), Square Kilometer Array (SKA) and other facilities. For relatively bright bursts, spectroscopic measurements of molecular and atomic absorption lines due to ambient protostellar gas may be possible. Utilizing models of primordial protostellar clouds, we show that under certain conditions, appreciable absorption ...

  5. Determination of phospholipids in soybean lecithin samples via the phosphorus monoxide molecule by high-resolution continuum source graphite furnace molecular absorption spectrometry.

    Science.gov (United States)

    Pires, Laís N; Brandão, Geovani C; Teixeira, Leonardo S G

    2017-06-15

    This paper presents a method for determining phospholipids in soybean lecithin samples by phosphorus determination using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) via molecular absorption of phosphorus monoxide. Samples were diluted in methyl isobutyl ketone. The best conditions were found to be 213.561nm with a pyrolysis temperature of 1300°C, a volatilization temperature of 2300°C and Mg as a chemical modifier. To increase the analytical sensitivity, measurement of the absorbance signal was obtained by summing molecular transition lines for PO surrounding 213nm: 213.561, 213.526, 213.617 and 213.637nm. The limit of detection was 2.35mgg(-1) and the precision, evaluated as relative standard deviation (RSD), was 2.47% (n=10) for a sample containing 2.2% (w/v) phosphorus. The developed method was applied for the analysis of commercial samples of soybean lecithin. The determined concentrations of phospholipids in the samples varied between 38.1 and 45% (w/v). Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Simultaneous determination of ofloxacin and cefixime by first and ratio first derivative UV spectrophotometry

    Directory of Open Access Journals (Sweden)

    Mahesh Attimarad

    2011-01-01

    Full Text Available Aim: Derivative spectrophotometry offers a useful approach for the analysis of drugs in multicomponent mixtures. Objective of the current study was to develop simple and rapid simultaneous methods for the determination of ofloxacin (OFX and cefixime trihydrate (CEF in bulk and pharmaceutical formulations. Materials and Methods: Two UV spectroscopic methods were developed and assessed for their feasibility in the simultaneous estimation. The first method was based on the first derivative absorption at 282.8 nm for OFX (zero crossing for CEF and at 318.6 nm for CEF (zero crossing for OFX. The method was applied in the concentration of 2 ΅g/ml to 20 ΅g/ml. Alternatively, the ratio derivative spectrophotometry method was developed making use of amplitude in first derivative of corresponding ratio spectra at 337.2 nm (maxima and 317 nm (maxima to estimate OFX and CEF, respectively. Results: The results showed higher correlation coefficient (~0.999 in both the proposed methods. Further, the methods were validated for precision, accuracy and assessed the drug content in bulk drug and formulation. Moreover, the data observed indicated also suggest that no interference of excipients during the estimation. Conclusion: The study concludes that the proposed methods are simple, rapid, sensitive, accurate and reproducible and could be an alternative to the existing chromatographical methods for the simultaneous determination of OFX and CEF in pharmaceutical dosage forms and in dissolution studies.

  7. Evaluation of angiotensin-converting enzyme inhibitor's absorption with retention data of micellar thin-layer chromatography and suitable molecular descriptor.

    Science.gov (United States)

    Odovic, Jadranka; Markovic, Bojan; Vladimirov, Sote; Karljikovic-Rajic, Katarina

    2015-01-01

    Twelve angiotensin-converting enzyme (ACE) inhibitors were studied to evaluate correlation between their absorption (ABS) data available in the literature (22-96%) and hydrophobicity parameters (km and Pm/w) obtained in micellar thin-layer chromatography (MTLC) using Brij 35. The theoretical considerations showed that the geometric molecular descriptor-volume value (Vol) should be considered as an independent variable simultaneously with calculated hydrophobicity parameters in multiple linear regression analysis to obtain reliable correlation between ACE inhibitor's absorption and lipophilicity (calculated KOWWINlog P) and that captopril should be excluded from further correlations. The results of MTLC confirmed that between the two hydrophobicity parameters km and Pm/w, for absorption prediction of 11 ACE inhibitors, the micelle-water partition coefficient Pm/w provided higher correlation (R(2) = 0.756), while for the km parameter R(2) = 0.612 was obtained. The micelle-water partition coefficient Pm/w could be considered as analogous to hydrophobicity parameter C0 from reversed-phase thin-layer chromatography. Dissimilar retention behavior of lisinopril indicated its lowest non-polar interaction with micelle, because of its di-acid form. The proposed model which included ACE inhibitors on the opposite site of lipophilicity-lisinopril and fosinopril (KOWWINlog P = -0.96 and KOWWINlog P = 6.61, respectively), both with similar absorption values (25 and 36%, respectively), could indicate that absorption of investigated compounds occurs via two different mechanisms: active and passive transport. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. OH concentration in an atmospheric-pressure methane-air flame from molecular-beam mass spectrometry and laser-absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cattolica, R.J.; Yoon, S.; Knuth, E.L.

    1982-01-01

    In evaluating experimental techniques for studying premixed atmospheric-pressure methane-air flames, analysts demonstrated that the molecular-beam mass-spectrometry technique adequately measures OH concentration, given careful design of the sampling probe and appropriate consideration for possible mass interferences. Perturbation of the OH concentration profile using various sampling probes indicates the importance of minimizing the length of the sampling-orifice channel to reduce composition relaxation during sampling. The accuracy of the MBMS method was determined by comparing the results with those from a laser-absorption spectroscopy system.

  9. Determination of sulfur in bovine serum albumin and L-cysteine using high-resolution continuum source molecular absorption spectrometry of the CS molecule

    Science.gov (United States)

    Andrade-Carpente, Eva; Peña-Vázquez, Elena; Bermejo-Barrera, Pilar

    2016-08-01

    In this study, the content of sulfur in bovine serum albumin and L-cysteine was determined using high-resolution continuum source molecular absorption spectrometry of the CS molecule, generated in a reducing air-acetylene flame. Flame conditions (height above the burner, measurement time) were optimized using a 3.0% (v/v) sulfuric acid solution. A microwave lab station (Ethos Plus MW) was used for the digestion of both compounds. During the digestion step, sulfur was converted to sulfate previous to the determination. Good repeatability (4-10%) and analytical recovery (91-106%) was obtained.

  10. Communication: Systematic shifts of the lowest unoccupied molecular orbital peak in x-ray absorption for a series of 3d metal porphyrins

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; Cook, P. L.; Himpsel, F. J.

    2010-01-01

    Porphyrins are widely used as dye molecules in solar cells. Knowing the energies of their frontier orbitals is crucial for optimizing the energy level structure of solar cells. We use near edge x-ray absorption fine structure (NEXAFS) spectroscopy to obtain the energy of the lowest unoccupied...... molecular orbital (LUMO) with respect to the N-1s core level of the molecule. A systematic energy shift of the N-1s to LUMO transition is found along a series of 3d metal octaethylporphyrins and explained by density functional theory. It is mainly due to a shift of the N-1s level rather than a shift...

  11. Solvent dependence of the molecular order in ion-exchanged self-assembled dialkylammonium monolayers on mica studied with soft X-ray absorption.

    Science.gov (United States)

    Hähner, Georg; Zwahlen, Mathias; Caseri, Walter

    2005-11-01

    Dialkyldimethylammonium films on mica prepared via ion exchange from solution have been reported to be of high quality in terms of their density and molecular orientation. Different preparation procedures are described in the literature. The molecular order and the inclination of the alkyl chains, however, are often deduced from indirect experimental evidence such as the wettability and the film thickness. In the present study we employed near edge X-ray absorption fine structure spectroscopy (NEXAFS) to determine directly the order of the molecules adsorbed from different solvents (water, methanol, water/methanol 1:1, cyclohexanol, and chloroform). It was found that films prepared from different solvents are displaying large differences in the established surface coverage and orientation. In particular, NEXAFS disclosed that the orientation of the alkyl chains can differ significantly even when similar water contact angle values are observed.

  12. Saturated absorption in a rotational molecular transition at 2.5 THz using a quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Consolino, L., E-mail: luigi.consolino@ino.it; Campa, A.; Ravaro, M.; Mazzotti, D.; Bartalini, S.; De Natale, P. [INO, Istituto Nazionale di Ottica-CNR, Largo E. Fermi 6, Firenze I-50125 (Italy); LENS, European Laboratory for Non-Linear Spectroscopy, Via N. Carrara 1, Sesto Fiorentino, I-50019 (Italy); Vitiello, M. S. [NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa I-56127 (Italy)

    2015-01-12

    We report on the evidence of saturation effects in a rotational transition of CH{sub 3}OH around 2.5 THz, induced by a free-running continuous-wave quantum cascade laser (QCL). The QCL emission is used for direct-absorption spectroscopy experiments, allowing to study the dependence of the absorption coefficient on gas pressure and laser intensity. A saturation intensity of 25 μW/mm{sup 2}, for a gas pressure of 17 μbar, is measured. This result represents the initial step towards the implementation of a QCL-based high-resolution sub-Doppler THz spectroscopy, which is expected to improve by orders of magnitude the precision of THz spectrometers.

  13. Molecular gas in absorption and emission along the line of sight to W31C G10.62-0.38

    CERN Document Server

    Liszt, Harvey

    2015-01-01

    We used the ARO 12m antenna to observe emission from the J=1-0 lines of carbon monoxide, \\hcop\\ and HNC and the J=2-1 line of CS toward and around the continuum peak used for absorption studies and we compare them with CH, HNC, C\\p\\ and other absorption spectra from PRISMAS. We develop a kinematic analysis that allows a continuous description of the spectral properties and relates them to viewing geometry in the Galaxy. As for CH, HF, C\\p, \\hcop\\ and other species observed in absorption, mm-wave emission in CO, \\hcop, HNC and CS is continuous over the full velocity range expected for material between the Sun and W31 4.95 kpc away. CO emission is much stronger than average in the Galactic molecular ring and the mean \\HH\\ density derived from CH, $4 \\pccc \\la$ 2$$ $\\la 10 \\pccc$ at 4 $\\la$ R $\\la$ 6.4 kpc, is similarly elevated. The CO-\\HH\\ conversion factor falls in a narrow range \\XCO\\ $= 1-2\\times10^{20}~\\HH\\ \\pcc~({\\rm K}-\\kms)^{-1}$ if the emitting gas is mostly on the near side of the sub-central point, a...

  14. Moderate resolution spectrophotometry of high redshift quasars

    Science.gov (United States)

    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.

  15. Determination of arsenic in air particulates and diesel exhaust particulates by spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    S. M. Talebi; M. Abedi

    2005-01-01

    A method was developed for the determination of trace arsenic by spectrophotometry. The proposed method is rapid, simple,and inexpensive. This method can be used for sensitive determination of trace arsenic in environmental samples and especially in air particulates. The results obtained by this method as a proposed method were compared with those obtained by hydride generation atomic absorption spectrometry as a popular reported method for the determination of arsenic and an excellent agreement was found between them. The method was also used for determination of arsenic associated with airborne particulate matter and diesel exhaust particulates.The results showed that considerable amount of arsenic are associated with diesel engine particulates. The variation in concentration of arsenic was also investigated. The atmospheric concentration of arsenic was different in different sampling stations was dependent to the traffic density.

  16. Beyond the electric-dipole approximation: A formulation and implementation of molecular response theory for the description of absorption of electromagnetic field radiation

    Energy Technology Data Exchange (ETDEWEB)

    List, Nanna Holmgaard, E-mail: nhl@sdu.dk; Jensen, Hans Jørgen Aagaard [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Kauczor, Joanna; Norman, Patrick, E-mail: panor@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, Linköping SE 58183 (Sweden); Saue, Trond [Laboratoire de Chimie et Physique Quantiques, UMR 5626—CNRS/Université Toulouse III (Paul Sabatier), 118 route de Narbonne, F-31062 Toulouse Cedex (France)

    2015-06-28

    We present a formulation of molecular response theory for the description of a quantum mechanical molecular system in the presence of a weak, monochromatic, linearly polarized electromagnetic field without introducing truncated multipolar expansions. The presentation focuses on a description of linear absorption by adopting the energy-loss approach in combination with the complex polarization propagator formulation of response theory. Going beyond the electric-dipole approximation is essential whenever studying electric-dipole-forbidden transitions, and in general, non-dipolar effects become increasingly important when addressing spectroscopies involving higher-energy photons. These two aspects are examined by our study of the near K-edge X-ray absorption fine structure of the alkaline earth metals (Mg, Ca, Sr, Ba, and Ra) as well as the trans-polyenes. In following the series of alkaline earth metals, the sizes of non-dipolar effects are probed with respect to increasing photon energies and a detailed assessment of results is made in terms of studying the pertinent transition electron densities and in particular their spatial extension in comparison with the photon wavelength. Along the series of trans-polyenes, the sizes of non-dipolar effects are probed for X-ray spectroscopies on organic molecules with respect to the spatial extension of the chromophore.

  17. Speciation of zinc in low molecular weight proteins of breast milk and infant formulas by size exclusion chromatography/flame atomic absorption spectroscopy.

    Science.gov (United States)

    Bermejo, P; Peña, E M; Fompedriña, D; Domínguez, R; Bermejo, A; Cocho, J A; Fernández, J R; Fraga, J M

    2001-01-01

    Size exclusion chromatography (SEC) and flame atomic absorption spectroscopy (FAAS) were used for the separation of metal-containing species in milk whey. After milk ultracentrifugation, the sample was injected into a TSK-Gel G2000 glass column and eluted with 0.2M NH4NO3-NH3, pH 6.7. Low molecular weight proteins were fractionated, and the fractions were characterized by molecular weight. Zinc distributions were obtained by FAAS using a high performance nebulizer. The method was very sensitive (limit of detection = 2.6 x 10(-3) microg/mL; limit of quantitation = 8.9 x 10(-3) microg/mL) and precise (RSDs < or =10%). This method was applied to the determination of Zn in binding compounds in breast milk whey and in commercial cow's milk-based formulas. Distribution patterns were different. The presence of Zn in most fractions in breast milk was most significant, whereas in infant formulas Zn was detected only in fractions of molecular weight <5 kDa and in the highest molecular weight peak.

  18. An important improvement in Ferron-timed spectrophotometry

    NARCIS (Netherlands)

    Zhang, Jing; Chang, Fang; Ren, Yijin; Shi, Qiuyi

    Ferron dosage ([Ferron]) is key to ferron-timed spectrophotometry (ferron assay). In order to clarify some important questions, the following studies were conducted: (1) The effect of [Ferron] on the sensitivity of total aluminum (AlT) determination was experimentally investigated and ²⁷Al nuclear

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

    Science.gov (United States)

    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…

  20. An important improvement in Ferron-timed spectrophotometry

    NARCIS (Netherlands)

    Zhang, Jing; Chang, Fang; Ren, Yijin; Shi, Qiuyi

    2013-01-01

    Ferron dosage ([Ferron]) is key to ferron-timed spectrophotometry (ferron assay). In order to clarify some important questions, the following studies were conducted: (1) The effect of [Ferron] on the sensitivity of total aluminum (AlT) determination was experimentally investigated and ²⁷Al nuclear m

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

    Science.gov (United States)

    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)

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

    Science.gov (United States)

    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…

  3. A Computer-aided Learning Exercise in Spectrophotometry.

    Science.gov (United States)

    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)

  4. Applied Spectrophotometry: Analysis of a Biochemical Mixture

    Science.gov (United States)

    Trumbo, Toni A.; Schultz, Emeric; Borland, Michael G.; Pugh, Michael Eugene

    2013-01-01

    Spectrophotometric analysis is essential for determining biomolecule concentration of a solution and is employed ubiquitously in biochemistry and molecular biology. The application of the Beer-Lambert-Bouguer Lawis routinely used to determine the concentration of DNA, RNA or protein. There is however a significant difference in determining the…

  5. Determinação de cobre, ferro, manganês e zinco, num mesmo extrato de planta, por potometria de chama de absorção The determination of copper, iron, manganese and zinc in a bulk plant extract by atomic absorption spectrophotometry

    Directory of Open Access Journals (Sweden)

    J. Romano Gallo

    1971-05-01

    Full Text Available É apresentado um método de determinação, num mesmo extrato de planta, de ferro, manganês e zinco na fase aquosa, e de cobre, após sua extração em solvente orgânico. Para êsse estudo usou-se um analisador automático de absorção atômica Perkin-Elmer, modêlo 4A. Somente á silica, em certas concentrações, poderá constituir problema na determinação de manganês ou ferro, na ausência de cálcio. Na extração quantitativa do cobre é necessário conservar o pH abaixo de 2, para evitar interferência de ferro.A method was developed to determine quantitatively Cu, Fe, Mn and Zn in a bulk plant extract, using flame absorption photometry. The process measures Fe, Mn and Zn directly in the aqueous solution, but a concentration of the extract with organic solvents is required for copper determination. Essentially the process consists in obtaining the plant extract through digestion of 1.000 g of the ground dry samples, with HNO3 and later with HC10(4-H2S0(4 (7:1 v/v, then the solution is diluted to 50 ml with water. Thirty ml of this solution are transferred to a separatory funnel, where the copper is extracted by the ammonium pyrrolidine dithiocarbamate/ methyl isobutyl ketone system, and its amount determined. It is necessary to keep the pH below 2 to avoid interference of Fe on Cu determination. Mn, Fe and Zn are determined directly in the remaining 20 ml of plant extract. It has been noticed that silicon might cause some problems in the determination of Fe and Mn, in the absence of Ca. All the determinations were made in a Perkin-Elmer mod. 4A atomic absorption automatic analyser.

  6. Determination of chlorine via the CaCl molecule by high-resolution continuum source graphite furnace molecular absorption spectrometry and direct solid sample analysis.

    Science.gov (United States)

    Guarda, Ananda; Aramendía, Maite; Andrés, Irene; García-Ruiz, Esperanza; do Nascimento, Paulo Cícero; Resano, Martín

    2017-01-01

    This work investigates the possibilities of high-resolution continuum source graphite furnace molecular absorption spectrometry for the direct determination of Cl in solid samples via the CaCl molecule and measurement of its molecular absorption. The method proposed is based on addition of 400µg Ca as molecule-forming reagent and of 20µgPd as chemical modifier, which helps to stabilize the analyte and enhances sensitivity. The molecular spectrum for CaCl offers different lines with different limits of detection and linear ranges, which permitted to analyze solid samples with different Cl contents. The lowest limit of detection (0.75ng Cl, corresponding to 0.75µgg(-1) for a typical sample mass of 1mg) could be achieved by combination of three of the most sensitive lines in the vicinity of 620.862nm, while the amplest linear range (up to 860ng Cl) was achieved by selection of the less sensitive line at 377.501nm. The method developed enabled the direct determination of Cl in solid samples using simple external calibration with aqueous standards. Good precision (5-9% RSD) and accuracy was attained in a series of certified samples of very different nature (i.e. coal, iron oxide, polyethylene, human hair, pine needles, rice flour and milk) and with very different Cl contents, ranging from about 50µgg(-1) to 1% (w/w) Cl. The method appears as particularly useful for Cl determination in samples with elevated Ca contents, for which biased results with other diatomic molecules, such as AlCl or SrCl, may be obtained. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Kramers-Kronig analysis of molecular evanescent-wave absorption spectra obtained by multimode step-index optical fibers.

    Science.gov (United States)

    Potyrailo, R A; Ruddy, V P; Hieftje, G M

    1996-07-20

    Spectral distortions that arise in evanescent-wave absorption spectra obtained with multimode step-index optical fibers are analyzed both theoretically and experimentally. Theoretical analysis is performed by the application of Kramers-Kronig relations to the real and the imaginary parts of the complex refractive index of an absorbing external medium. It is demonstrated that even when the extinction coefficient of the external medium is small, anomalous dispersion of that medium in the vicinity of an absorption band must be considered. Deviations from Beer's law, band distortions, and shifts in peak position are quantified theoretically as a function of the refractive index and the extinction coefficient of the external medium; the effect of bandwidth for both Lorentzian and Gaussian bands is also evaluated. Numerical simulations are performed for two types of sensing sections in commonly used plastic-clad silica optical fibers. These sensors include an unclad fiber in contact with a lower-index absorbing liquid and a fiber with the original cladding modified with an absorbing species. The numerical results compare favorably with those found experimentally with these types of sensing sections.

  8. Strontium mono-chloride — A new molecule for the determination of chlorine using high-resolution graphite furnace molecular absorption spectrometry and direct solid sample analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Éderson R. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Welz, Bernhard, E-mail: w.bernardo@terra.com.br [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil); Lopez, Alfredo H.D.; Gois, Jefferson S. de; Caramori, Giovanni F. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Borges, Daniel L.G.; Carasek, Eduardo [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil); Andrade, Jailson B. de [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil)

    2014-12-01

    A new method has been developed for the determination of chlorine in biological reference materials using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) of the strontium mono-chloride (SrCl) molecule and direct solid sample analysis. The use of the SrCl molecule for high-temperature MAS was not described up to now in the literature. Preliminary time-dependent density functional theory calculations of the SrCl structure were carried out in order to obtain reasonable estimates of the absorption spectrum of the target molecule. The calculations, which were carried out at BHandHLyp/def2-QZVP level of theory, proved a very accurate and inexpensive way to get information about the spectrum of the SrCl molecule, which enabled us to perform the Cl determination with good sensitivity and specificity. The molecular absorption of the SrCl molecule has been measured using the wavelength at 635.862 nm, and zirconium and palladium have been evaluated as the chemical modifiers in order to increase the sensitivity of the gaseous SrCl molecule generated in the graphite furnace. The pyrolysis and vaporization temperatures were 600 °C and 2300 °C, respectively. Accuracy and precision of the method have been evaluated using biological certified reference materials of both animal and plant origins, showing good agreement with the informed and certified values. Limit of detection and characteristic mass were 1.0 and 2.2 ng, respectively. The results found using HR-CS GF MAS were in agreement (95% confidence level) compared to those obtained by electrothermal vaporization-inductively coupled plasma mass spectrometry. - Highlights: • The spectrum of the SrCl molecule was calculated on a theoretical basis and found very close to the predicted wavelength. • It is the first time that the spectrum of the SrCl molecule is described and used analytically for the determination of Cl. • No spectral interferences were observed as the

  9. The solvent shell structure of aqueous iodide: X-ray absorption spectroscopy and classical, hybrid QM/MM and full quantum molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pham, V.T. [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); Tavernelli, I. [Ecole Polytechnique Federale de Lausanne, Laboratoire de chimie et biochimie computationnelles, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); Milne, C.J.; van der Veen, R.M. [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); D' Angelo, P. [Dipartimento di Chimica, Universita di Roma ' La Sapienza' , Ple A. Moro 5, 00185 Roma (Italy); Bressler, Ch. [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); Chergui, M., E-mail: Majed.Chergui@epfl.ch [Ecole Polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland)

    2010-05-25

    Graphical abstract: The L{sub 3}-edge EXAFS spectra of aqueous iodide are compared to classical, QM/MM and DFT-based molecular dynamics simulations. The QM/MM simulations reproduce best the experimental data. An anisotropy of the solvation shell is also identified. - Abstract: The L{sub 3} X-ray absorption spectrum of aqueous iodide is reported, and its EXAFS is compared to theoretical spectra reconstructed from the radial distribution function of the iodide hydration obtained from classical, hybrid Quantum Mechanics Molecular Mechanics, (QM/MM) and full quantum (density functional theory, DFT) molecular dynamics simulations. Since EXAFS is mainly sensitive to short distances around the iodide ion, it is a direct probe of the local solvation structure. The comparison shows that QM/MM simulations deliver a satisfactory description of the EXAFS signal, while nonpolarizable classical simulations are somewhat less satisfactory and DFT-based simulations perform poorly. We also identify a weak anisotropy of the water solvation shell around iodide, which may be of importance in electron photoejection experiments.

  10. Optimization of fluorine determination via the molecular absorption of gallium mono-fluoride in a graphite furnace using a high-resolution continuum source spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Gleisner, Heike, E-mail: H.Gleisner@analytik-jena.d [Analytik Jena AG, Konrad-Zuse-Str. 1, 07745 Jena (Germany); Welz, Bernhard [Departamento de Quimica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis-SC (Brazil); Instituto Nacional de Ciencia e Tecnologia do CNPq-INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170 Salvador, BA (Brazil); Einax, Juergen W. [Department of Environmental Analysis, Institute of Inorganic und Analytical Chemistry, Friedrich Schiller University of Jena, Lessingstr. 8, 07743 Jena (Germany)

    2010-09-15

    The determination of fluorine using the molecular absorption of gallium mono-fluoride (GaF) at the 211.248 nm rotational line has been optimized using a commercially available high-resolution continuum source atomic absorption spectrometer with a transversely heated graphite tube furnace. The electron excitation spectrum of GaF was generated by adding 500 {mu}g Ga per injection into the graphite tube as molecule forming reagent. Best results were obtained by applying Zr as a permanent modifier and a mixed Pd/Zr modifier, thermally pretreated before each sample injection together with the Ga reagent at 1100 {sup o}C. The use of sodium acetate and Ru(III) nitrosyl nitrate as additional modifiers injected together with the sample further improved the performance. This way a maximum pyrolysis temperature of 550 {sup o}C could be used, and the optimum molecule forming temperature was 1550 {sup o}C. Several drinking water samples, a mineral water sample, and two certified reference materials were analyzed using the standard calibration technique; the absence of potential matrix effects was verified by measuring different dilutions and spiking with known fluorine mass. The results were in good agreement with the certified values and those measured by ion selective electrode; the recovery rate for the spiking experiments was between 97% and 106%. The results show that there was no matrix influence for that kind of samples containing relatively high concentrations of Ca, Mg and chloride, which are known to cause interference in GaF molecule absorption. The limit of detection and the characteristic mass of the method were 5.2 and 7.4 pg F, respectively, and were both about a factor of two better than recently published values.

  11. [The effect of electromagnetic waves of very high frequency of molecular spectra of radiation and absorption of nitric oxide on the functional activity of platelets].

    Science.gov (United States)

    Kirichuk, V F; Maĭborodin, A V; Volin, M V; Krenitskiĭ, A P; Tupikin, V D

    2001-01-01

    A study was made of the effect of electromagnetic EMI MMD-fluctuation on the frequencies of molecular spectra of radiation, and nitric oxide absorption under in vitro conditions on the functional activity of platelets in patients with unstable angina pectoris, with the help of a specially created generator. At amplitude-modulated and continuous modes of EMI MMD-irradiation of platelet-rich plasma for 5, 15 and 30 min the platelet functional activity decreases, which was shown up in reduction of their activation and fall of aggregative ability. The degree, to which platelet functional activity was inhibited, depended on the mode of irradiation and on duration of EMI MMD effect. The most obvious changes in platelet activation and in their readiness to aggregative response were observed at a continuous mode of irradiation within a 15 min interval.

  12. Determination of sulfur in human hair using high resolution continuum source graphite furnace molecular absorption spectrometry and its correlation with total protein and albumin

    Science.gov (United States)

    Ozbek, Nil; Baysal, Asli

    2017-04-01

    Human hair is a valuable contributor for biological monitoring. It is an information storage point to assess the effects of environmental, nutritional or occupational sources on the body. Human proteins, amino acids or other compounds are among the key components to find the sources of different effects or disorders in the human body. Sulfur is a significant one of these compounds, and it has great affinity to some metals and compounds. This property of the sulfur affects the human health positively or negatively. In this manuscript, sulfur was determined in hair samples of autistic and age-match control group children via molecular absorption of CS using a high-resolution continuum source graphite furnace atomic absorption spectrometer. For this purpose, hair samples were appropriately washed and dried at 75 °C. Then samples were dissolved in microwave digestion using HNO3 for sulfur determination. Extraction was performed with HCl hydrolysation by incubation for 24 h at 110 °C for total protein and albumin determination. The validity of the method for the sulfur determination was tested using hair standard reference materials. The results were in the uncertainty limits of the certified values at 95% confidence level. Finally correlation of sulfur levels of autistic children's hair with their total protein and albumin levels were done.

  13. Probing Lewis Acid-Base Interactions with Born-Oppenheimer Molecular Dynamics: The Electronic Absorption Spectrum of p-Nitroaniline in Supercritical CO2.

    Science.gov (United States)

    Cabral, Benedito J Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

    2015-07-02

    The structure and dynamics of p-nitroaniline (PNA) in supercritical CO2 (scCO2) at T = 315 K and ρ = 0.81 g cm(-3) are investigated by carrying out Born-Oppenheimer molecular dynamics, and the electronic absorption spectrum in scCO2 is determined by time dependent density functional theory. The structure of the PNA-scCO2 solution illustrates the role played by Lewis acid-base (LA-LB) interactions. In comparison with isolated PNA, the ν(N-O) symmetric and asymmetric stretching modes of PNA in scCO2 are red-shifted by -17 and -29 cm(-1), respectively. The maximum of the charge transfer (CT) absorption band of PNA in scSCO2 is at 3.9 eV, and the predicted red-shift of the π → π* electronic transition relative to the isolated gas-phase PNA molecule reproduces the experimental value of -0.35 eV. An analysis of the relationship between geometry distortions and excitation energies of PNA in scCO2 shows that the π → π* CT transition is very sensitive to changes of the N-O bond distance, strongly indicating a correlation between vibrational and electronic solvatochromism driven by LA-LB interactions. Despite the importance of LA-LB interactions to explain the solvation of PNA in scCO2, the red-shift of the CT band is mainly determined by electrostatic interactions.

  14. Solid sampling determination of total fluorine in baby food samples by high-resolution continuum source graphite furnace molecular absorption spectrometry.

    Science.gov (United States)

    Ozbek, Nil; Akman, Suleyman

    2016-11-15

    This study describes the applicability of solid sampling technique for the determination of fluorine in various baby foods via molecular absorption of calcium monofluoride generated in a graphite furnace of high-resolution continuum source atomic absorption spectrometry. Fluorine was determined at CaF wavelength, 606.440nm in a graphite tube applying a pyrolysis temperature of 1000°C and a molecule forming temperature of 2200°C. The limit of detection and characteristic mass of the method were 0.20ng and 0.17ng of fluorine, respectively. The fluorine concentrations determined in standard reference sample (bush branches and leaves) were in good agreement with the certified values. By applying the optimized parameters, the concentration of fluorine in various baby foods were determined. The fluorine concentrations were ranged from

  15. Absorption of CO2 in the ionic liquid 1-n-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([hmim][FEP]): a molecular view by computer simulations.

    Science.gov (United States)

    Zhang, Xiaochun; Huo, Feng; Liu, Zhiping; Wang, Wenchuan; Shi, Wei; Maginn, Edward J

    2009-05-28

    Using a computational screening methodology, we predicted (AIChE J. 2008, 54, 2717) that the anion tris(pentafluoroethyl)trifluorophosphate ([FEP]) should increase the solubility of CO2 in ionic liquids (ILs) relative to a wide range of conventional anions. This prediction was confirmed experimentally. In this work, we develop a united-atom force field for the [FEP] anion and use the continuous fractional component Monte Carlo (CFC MC) method to predict CO2 absorption isotherms in 1-n-hexyl-3-methylimidazolium ([hmim]) [FEP] at 298.2 and 323.2 K and pressures up to 20.0 bar. The simulated isotherms overestimate the solubility of CO2 by about 20% but capture the experimental trends quite well. Additional Monte Carlo (MC) and molecular dynamics (MD) simulations are performed to study the mechanisms of CO2 absorption in [hmim][FEP] and [hmim][PF6]. The site-site radial distribution functions (RDFs) show that CO2 is highly organized around the [PF6] anion due to its symmetry and smaller size, while less ordered distributions were found around [FEP] and [hmim]. However, more CO2 can be found in the first coordination shell of [FEP] compared with [PF6]. The structures of ILs, illustrated by P-P radial distribution functions, change very little upon the addition of as much as 50 mol % CO2. An energetic analysis shows that the van der Waals interactions between CO2 and ILs are generally larger than electrostatic interactions.

  16. Constraint on a varying proton-to-electron mass ratio from molecular hydrogen absorption toward quasar SDSS J123714.60+064759.5

    CERN Document Server

    Daprà, M; Murphy, M T; Ubachs, W

    2015-01-01

    Molecular hydrogen transitions in the sub-damped Lyman alpha absorber at redshift z = 2.69, toward the background quasar SDSS J123714.60+064759.5, were analyzed in order to search for a possible variation of the proton-to-electron mass ratio mu over a cosmological time-scale. The system is composed of three absorbing clouds where 137 H2 and HD absorption features were detected. The observations were taken with the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a signal-to-noise ratio of 32 per 2.5 km/s pixel, covering the wavelengths from 356.6 to 409.5 nm. A comprehensive fitting method was used to fit all the absorption features at once. Systematic effects of distortions to the wavelength calibrations were analyzed in detail from measurements of asteroid and `solar twin' spectra, and were corrected for. The final constraint on the relative variation in mu between the absorber and the current laboratory value is dmu/mu = (-5.4 \\pm 6.3 stat \\pm 4.0 syst) x 10^(-6), consistent with no va...

  17. Determination of Ammonia-nitrogen in the Dyeing Wastewater by the Gas-phase Molecular Absorption Spectrometry%气相分子吸收光谱法测定印染废水中的氨氮

    Institute of Scientific and Technical Information of China (English)

    徐运; 肖国起

    2011-01-01

    本文用气相分子吸收光谱法测定印染废水中的氨氮。气相分子吸收光谱法应用国内的气相分子吸收光谱仪测定印染废水中氨氮,与纳氏试剂法相比较,该方法快捷简单、受干扰小、分析精度高。%This paper introduced the gas-phase molecular absorption spectrometry for the ammonia-nitrogen in the dyeing wastewater.The gas-phase molecular absorption spectrometry applied the as-phase molecular absorption spectrophotometer device to analyze the ammonia-nitrogen in the dyeing wastewater.Compared with the Nesster's reagent colorimetric method,this method was fast,simple,less-disturbance and highly perceptive.

  18. Method development for the determination of bromine in coal using high-resolution continuum source graphite furnace molecular absorption spectrometry and direct solid sample analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Éderson R.; Castilho, Ivan N.B. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Welz, Bernhard, E-mail: w.bernardo@terra.com.br [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil); Gois, Jefferson S. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Borges, Daniel L.G. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil); Carasek, Eduardo [Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil); Andrade, Jailson B. de [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, 40170-115 Salvador, BA (Brazil)

    2014-06-01

    This work reports a simple approach for Br determination in coal using direct solid sample analysis in a graphite tube furnace and high-resolution continuum source molecular absorption spectrometry. The molecular absorbance of the calcium mono-bromide (CaBr) molecule has been measured using the rotational line at 625.315 nm. Different chemical modifiers (zirconium, ruthenium, palladium and a mixture of palladium and magnesium nitrates) have been evaluated in order to increase the sensitivity of the CaBr absorption, and Zr showed the best overall performance. The pyrolysis and vaporization temperatures were 800 °C and 2200 °C, respectively. Accuracy and precision of the method have been evaluated using certified coal reference materials (BCR 181, BCR 182, NIST 1630a, and NIST 1632b) with good agreement (between 98 and 103%) with the informed values for Br. The detection limit was around 4 ng Br, which corresponds to about 1.5 μg g{sup −1} Br in coal, based on a sample mass of 3 mg. In addition, the results were in agreement with those obtained using electrothermal vaporization inductively coupled plasma mass spectrometry, based on a Student t-test at a 95% confidence level. A mechanism for the formation of the CaBr molecule is proposed, which might be considered for other diatomic molecules as well. - Highlights: • Bromine has been determined in coal using direct solid sample analysis. • Calibration has been carried out against aqueous standard solutions. • The coal samples and the molecule-forming reagent have been separated in order to avoid interferences. • The results make possible to draw conclusions about the mechanisms of molecule formation.

  19. Enhancing the intestinal absorption of low molecular weight chondroitin sulfate by conjugation with α-linolenic acid and the transport mechanism of the conjugates.

    Science.gov (United States)

    Xiao, Yuliang; Li, Pingli; Cheng, Yanna; Zhang, Xinke; Sheng, Juzheng; Wang, Decai; Li, Juan; Zhang, Qian; Zhong, Chuanqing; Cao, Rui; Wang, Fengshan

    2014-04-25

    The purpose of this report was to demonstrate the effect of amphiphilic polysaccharides-based self-assembling micelles on enhancing the oral absorption of low molecular weight chondroitin sulfate (LMCS) in vitro and in vivo, and identify the transepithelial transport mechanism of LMCS micelles across the intestinal barrier. α-Linolenic acid-low molecular weight chondroitin sulfate polymers(α-LNA-LMCS) were successfully synthesized, and characterized by FTIR, (1)HNMR, TGA/DSC, TEM, laser light scattering and zeta potential. The significant oral absorption enhancement and elimination half-life (t₁/₂) extension of LNA-LMCS2 in rats were evidenced by intragastric administration in comparison with CS and LMCS. Caco-2 transport studies demonstrated that the apparent permeability coefficient (Papp) of LNA-LMCS2 was significantly higher than that of CS and LMCS (p<0.001), and no significant effects on the overall integrity of the monolayer were observed during the transport process. In addition, α-LNA-LMCS micelles accumulated around the cell membrane and intercellular space observed by confocal laser scanning microscope (CLSM). Furthermore, evident alterations in the F-actin cytoskeleton were detected by CLSM observation following the treatment of the cell monolayers with α-LNA-LMCS micelles, which further certified the capacity of α-LNA-LMCS micelles to open the intercellular tight junctions rather than disrupt the overall integrity of the monolayer. Therefore, LNA-LMCS2 with low cytotoxicity and high bioavailability might be a promising substitute for CS in clinical use, such as treating osteoarthritis, atherosclerosis, etc.

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

    Science.gov (United States)

    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.

  1. DEVELOPMENT OF THE TECHNIQUE OF QUANTITATIVE DEFINITION OF TRIAZAVIRIN IN WATER SOLUTIONS WITH USE OF THE SPECTROPHOTOMETRY METHOD

    OpenAIRE

    M. Yu. Kinev; O. A. Melnikova; A. Yu. Petro; D. V. Zaboyarkina

    2014-01-01

    Authors of article developed techniques of quantitative definition Triazavirin in water solutions with use of a method of a spectrophotometry. Three options of a method of a s spectrophotometry are used: direct spectrophotometry, spectrophotometry according to A.M. Firordt, a spectrophotometry with use of standard solution. For all techniques calculation of metrological characteristics is carried out. The developed techniques of quantitative definition were applicable for practical use in the...

  2. Local vibrational dynamics of hematite (α-Fe{sub 2}O{sub 3}) studied by extended x-ray absorption fine structure and molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: andrea.sanson@unipd.it [Dipartimento di Fisica e Astronomia - Università di Padova, Padova (Italy); Mathon, O.; Pascarelli, S. [ESRF - European Synchrotron Radiation Facility, Grenoble (France)

    2014-06-14

    The local vibrational dynamics of hematite (α-Fe{sub 2}O{sub 3}) has been investigated by temperature-dependent extended x-ray absorption fine structure spectroscopy and molecular dynamics simulations. The local dynamics of both the short and long nearest-neighbor Fe–O distances has been singled out, i.e., their local thermal expansion and the parallel and perpendicular mean-square relative atomic displacements have been determined, obtaining a partial agreement with molecular dynamics. No evidence of the Morin transition has been observed. More importantly, the strong anisotropy of relative thermal vibrations found for the short Fe–O distance has been related to its negative thermal expansion. The differences between the local dynamics of short and long Fe–O distances are discussed in terms of projection and correlation of atomic motion. As a result, we can conclude that the short Fe–O bond is stiffer to stretching and softer to bending than the long Fe–O bond.

  3. Investigation of chemical modifiers for sulfur determination in diesel fuel samples by high-resolution continuum source graphite furnace molecular absorption spectrometry using direct analysis

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Charles S. [Instituto Federal Sul-rio-grandense, Câmpus Pelotas, Pelotas, RS (Brazil); Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Vale, Maria Goreti R. [Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Welz, Bernhard [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Universidade Federal de Santa Catarina, Departamento de Química, Florianópolis, SC (Brazil); Andrade, Jailson B. [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Dessuy, Morgana B., E-mail: mbdessuy@ufrgs.br [Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil)

    2015-06-01

    High-resolution continuum source graphite furnace molecular absorption spectrometry has been applied for sulfur determination in diesel fuel. The sharp rotational lines of the carbon monosulfide molecule (formed during the vaporization step) were used to measure the absorbance. The analytical line at 258.056 nm was monitored using the sum of three pixels. Different chemical modifiers were investigated and the mixture of palladium and magnesium was used as chemical modifier in combination with iridium as permanent modifier. L-Cysteine was chosen as sulfur standard and the calibration was done against aqueous standard solutions. The proposed method was applied for the analyses of four diesel samples: two S10 samples and two S500 samples. The trueness of the method was checked with a certified reference material (CRM) of sulfur in diesel fuel (NIST 2724b). Accurate results, for samples and CRM, were achieved after a dilution with propan-1-ol. The following figures of merit were obtained: characteristic mass of 17 ± 3 ng, limit of detection and limit of quantification of 1.4 mg kg{sup −1} and 4.7 mg kg{sup −1}, respectively. - Highlights: • Ir, Ru and Zr were investigated as permanent modifiers. • Ca, Mg, Pd and Pd/Mg were investigated as modifiers in solution. • Indirect determination of sulfur monitoring the molecular absorbance of the CS • Direct analysis of diesel samples using a dilution in propan-1-ol.

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

    Science.gov (United States)

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

    2013-08-01

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

  5. Development of a Transnasal Delivery System for Recombinant Human Growth Hormone (rhGH): Effects of the Concentration and Molecular Weight of Poly-L-arginine on the Nasal Absorption of rhGH in Rats.

    Science.gov (United States)

    Kawashima, Ryo; Uchida, Masaki; Yamaki, Tsutomu; Ohtake, Kazuo; Hatanaka, Tomomi; Uchida, Hiroyuki; Ueda, Hideo; Kobayashi, Jun; Morimoto, Yasunori; Natsume, Hideshi

    2016-01-01

    A novel system for delivering recombinant human growth hormone (rhGH) that is noninvasive and has a simple method of administration is strongly desired to improve the compliance of children. The aim of this study was to investigate the potential for the intranasal (i.n.) co-administration of rhGH with poly-L-arginine (PLA) as a novel delivery system by evaluating the effects of the concentration and molecular weight of PLA on the nasal absorption of rhGH. The influence of the formation of insoluble aggregates and a soluble complex in the dosage formulation on nasal rhGH absorption was also evaluated by size-exclusion chromatography and ultrafiltration. PLA enhanced the nasal absorption of rhGH at each concentration and molecular weight examined. Nasal rhGH absorption increased dramatically when the PLA concentration was 1.0 % (w/v) due to the improved solubility of rhGH in the formulation. A delay in rhGH absorption was observed when the molecular weight of PLA was increased. This appeared to be because the increase in molecular weight caused the formation of a soluble complex. It seems that the PLA concentration affects the absorption-enhancing effect on rhGH, while the molecular weight of PLA affects the time when the maximum plasma rhGH concentration was reached (Tmax) of rhGH after i.n. administration, mainly because of the interactions among rhGH, PLA, and additives. Therefore, the transnasal rhGH delivery system using PLA is considered to be a promising alternative to subcutaneous (s.c.) injection if these interactions are sufficiently controlled.

  6. Elucidating the effects of cholesterol on the molecular packing of double-chained cationic lipid langmuir monolayers by infrared reflection-absorption spectroscopy.

    Science.gov (United States)

    Kuo, An-Tsung; Chang, Chien-Hsiang

    2015-01-01

    Cholesterol has been suggested to play a role in stable vesicle formation by adjusting the molecular packing of the vesicular bilayer. To explore the mechanisms involved in adjusting the bilayer structure by cholesterol, the molecular packing behavior in a mimic outer layer of cationic dialkyldimethylammonium bromide (DXDAB)/cholesterol vesicular bilayer was investigated by the Langmuir monolayer approach with infrared reflection-absorption spectroscopy (IRRAS). The results indicated that the addition of cholesterol in the DXDAB Langmuir monolayers not only restrained the desorption of the DXDAB with short hydrocarbon chains, such as ditetradecyldimethylammonium bromide or dihexadecyldimethylammonium bromide, into the aqueous phase but also induced a condensing effect on the DXDAB monolayers. At a liquid-expanded (LE) state, the ordering effect of cholesterol accompanying the condensing effect occurred in the mixed DXDAB/cholesterol monolayers due to the tendency of maximizing hydrocarbon chain contact between cholesterol and the neighboring hydrocarbon chains. However, for the mixed monolayers containing the DXDAB with long hydrocarbon chains, such as dioctadecyldimethylammonium bromide (DODAB), the disordering effect of cholesterol took place at a liquid-condensed (LC) state. This was related to the molecular structure of cholesterol and hydrocarbon chain length of DODAB. The rigid sterol ring of cholesterol hindered the portion of neighboring hydrocarbon chains from motion. However, the flexible alkyl side-chain of cholesterol along with the corresponding portion of neighboring hydrocarbon chains formed a fluidic region, counteracting the enhanced conformational order induced by the sterol ring of cholesterol. Furthermore, the long hydrocarbon chains of DODAB possessed a more pronounced motion freedom, resulting in a more disordered packing of the monolayers.

  7. Determination of olanzapine by spectrophotometry using permanganate

    Directory of Open Access Journals (Sweden)

    Nagaraju Rajendraprasad

    2009-09-01

    Full Text Available Two new spectrophotometric methods using permanganate as the oxidimetric reagent for the determination of olanzapine (OLP were developed and validated as per the current ICH guidelines. The methods involved the addition of known excess of permanganate to OLP in either acid or alkaline medium followed by the determination of unreacted permanganate at 550 nm (method A or bluish-green color of manganate at 610 nm (method B. The decrease in absorbance in method A or increase in absorbance in method B as a function of concentration of OLP was measured and related to OLP concentration. Under optimized conditions, Beer's law was obeyed over the ranges 2.0 to 20 and 1.0 to 10 μg mL-1 in method A and method B, respectively. The calculated molar absorptivity values were 1.34 x 10(4 and 2.54 x 10(4 l mol-1cm-1 for method A and method B respectively, and the respective Sandell sensitivities were 0.0233 and 0.0123 μg cm-2. The LOD and LOQ for method A were calculated to be 0.37 and 1.13 μg mL-1and the corresponding values for method B were 0.16 and 0.48 μg mL-1. Intermediate precision, expressed as RSD was in the range 0.51 to 2.66 %, and accuracy, expressed as relative error ranged from 0.79 to 2.24 %. The proposed methods were successfully applied to the assay of OLP in commercial tablets with mean percentage recoveries of 102 ±1.59 % (method A and 101 ±1.53 % (method B. The accuracy and reliability of the methods were further confirmed by performing recovery tests via standard addition procedure.Dois métodos espectrofotométricos novos, usando o permanganato como o reagente oxidimétrico para a determinação da olanzapina (OLP foram utilizados e validados de acordo com as diretrizes atuais do ICH. Os métodos envolveram a adição de excesso conhecido de permanganato à OLP em meio ácido ou alcalino, determinando-se o permanganato que não reagiu em 550 nm (método A, ou pela cor verde-azulada do manganato a 610 nm (método B. A diminuição da

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

    Science.gov (United States)

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

    1979-01-01

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

  9. Predicting absorption and dispersion in acoustics by direct simulation Monte Carlo: Quantum and classical models for molecular relaxation.

    Science.gov (United States)

    Hanford, Amanda D; O'Connor, Patrick D; Anderson, James B; Long, Lyle N

    2008-06-01

    In the current study, real gas effects in the propagation of sound waves are simulated using the direct simulation Monte Carlo method for a wide range of frequencies. This particle method allows for treatment of acoustic phenomena at high Knudsen numbers, corresponding to low densities and a high ratio of the molecular mean free path to wavelength. Different methods to model the internal degrees of freedom of diatomic molecules and the exchange of translational, rotational and vibrational energies in collisions are employed in the current simulations of a diatomic gas. One of these methods is the fully classical rigid-rotor/harmonic-oscillator model for rotation and vibration. A second method takes into account the discrete quantum energy levels for vibration with the closely spaced rotational levels classically treated. This method gives a more realistic representation of the internal structure of diatomic and polyatomic molecules. Applications of these methods are investigated in diatomic nitrogen gas in order to study the propagation of sound and its attenuation and dispersion along with their dependence on temperature. With the direct simulation method, significant deviations from continuum predictions are also observed for high Knudsen number flows.

  10. Excited state molecular structure determination in disordered media using laser pump/x-ray probe time-domain x-ray absorption spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L. X.; Chemistry

    2003-01-01

    Advances in X-ray technologies provide opportunities for solving structures of photoexcited state molecules with short lifetimes. Using X-ray pulses from a modern synchrotron source, the structure of a metal-to-ligand-charge-transfer (MLCT) excited state of CuI(dmp)2+ (dmp 1/4 2,9-dimethyl-1,10-phenanthroline) was investigated by laser pump/X-ray probe X-ray absorption fine structure (LPXP-XAFS) in fluid solution at room temperature on a nanosecond time scale. The experimental requirements for such pump-probe XAFS are described in terms of technical challenges: (1) conversion of optimal excited state population, (2) synchronization of the pump laser pulse and probe Xray pulse, and (3) timing of the detection. Using a laser pump pulse for the photoexcitation, a photoluminescent MLCT excited state of CuI(dmp)2(BArF), (dmp 1/4 2,9-dimethyl-1,10-phenanthroline), BArF 1/4 tetrakis(3,5-bis(trifluoromethylphenyl)borate) with a lifetime of 98{+-}5 ns was created. Probing the structure of this state at its optimal concentration using an X-ray pulse cluster with a total duration of 14.2 ns revealed that (1) a Cu{sup II} center was generated via a whole charge transfer; (2) the copper in the MLCT state bound an additional ligand to form a penta-coordinate complex with a likely trigonal bipyramidal geometry; and (3) the average Cu-N bond length increases in the MLCT excited state by 0.07 . In contrast to previously reported literature, the photoluminescence of this pentacoordinate MLCT state was not quenched upon ligation with the fifth ligand. On the basis of experimental results, we propose that the absorptive and emissive states have distinct geometries. The results represent X-ray characterization of a molecular excited state in fluid solution on a nanosecond time scale.

  11. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  12. Determination of fluorine in copper concentrate via high-resolution graphite furnace molecular absorption spectrometry and direct solid sample analysis - Comparison of three target molecules.

    Science.gov (United States)

    Cadorim, Heloisa R; de Gois, Jefferson S; Borges, Aline R; Vale, Maria Goreti R; Welz, Bernhard; Gleisner, Heike; Ott, Christina

    2018-01-01

    The chemical composition of complex inorganic materials, such as copper concentrate, may influence the economics of their further processing because most smelters, and particularly the producers of high-purity electrolyte copper, have strict limitations for the permissible concentration of impurities. These components might be harmful to the quality of the products, impair the production process and be hazardous to the environment. The goal of the present work is the development of a method for the determination of fluorine in copper concentrate using high-resolution graphite furnace molecular absorption spectrometry and direct solid sample analysis. The molecular absorption of the diatomic molecule CaF was measured at 606.440nm. The molecule CaF was generated by the addition of 200µg Ca as the molecule-forming reagent; the optimized pyrolysis and vaporization temperatures were 900°C and 2400°C, respectively. The characteristic mass and limit of detection were 0.5ng and 3ng, respectively. Calibration curves were established using aqueous standard solutions containing the major components Cu, Fe, S and the minor component Ag in optimized concentrations. The accuracy of the method was verified using certified reference materials. Fourteen copper concentrate samples from Chile and Australia were analyzed to confirm the applicability of the method to real samples; the concentration of fluorine ranged from 34 to 5676mgkg(-1). The samples were also analyzed independently at Analytik Jena by different operators, using the same equipment, but different target molecules, InF and GaF, and different operating conditions; but with a few exceptions, the results agreed quite well. The results obtained at Analytik Jena using the GaF molecule and our results obtained with CaF, with one exception, were also in agreement with the values informed by the supplier of the samples, which were obtained using ion selective electrode potentiometry after alkaline fusion. A comparison will

  13. 分子模拟活性炭的方法及其应用进展%Application of Molecular Simulation Methodology in Activated Carbon Absorption Properties

    Institute of Scientific and Technical Information of China (English)

    王国栋; 蒋剑春; 孙康

    2015-01-01

    介绍了分子模拟和传统吸附理论的关系,综述了使用巨正则蒙特卡洛模拟和密度泛函理论方法对活性炭结构的研究,归纳了近年来分子模拟技术在作为特殊吸附剂的活性炭的理论设计、吸附性能预测和指导表面基团改性方面应用过程中的研究进展。目前对活性炭微观孔结构的分子模拟研究,多停留于理论层面的模拟研究,而缺少对微观结构和宏观性质之间关系的分析。在实际应用中结合发挥分子模拟微观层面分析的优势,是分子模拟技术在活性炭研究中的重要发展方向。%Molecular simulation,a novel technology based on scientific computational method,is used in the research of absorption performance of activated carbon. The relation of molecular simulation and traditional adsorption was introduced. The application of grand canonical Monte Carlo ( MC) simulation and density functional theory ( DFT) in the structure analysis of activated carbon was reviewed in this article. The recent progress of designing specific activated carbon adsorbent, predicting the adsorption efficiency,and guiding the surface modification by molecular simulation were reviewed,too. Due to few research correlating the microscopic structure with macroscopic properties,recent simulation works of pore structure for activated carbon were in the stage of theoretical level. The technologies of molecular simulation is an important development trend in the field of activated carbon. This has advantages in simulating the microscopic structure.

  14. Identification of toxic and other matters in wines by the method of Atomic Absorption Spectrophotometry (AAS

    Directory of Open Access Journals (Sweden)

    Mr.Sc. Vlora Gashi

    2011-06-01

    Full Text Available Quality wines are produced in our country. The main objective of this paper was identification of toxic matter, heavy metals and minerals in wines as final produce, with a view of improving nutritional quality of our wines, produced in 2008-2009. Another important fact for this research was the determination of the presence of remnants from protective solutions containing toxic elements (Cu and Pb[1]. [1] Evgjini Papazisi Tonin Rjolli Dr. Abdul Sinani "Food Technology and Environ-mental Protection (Teknologji ushqimore dhe mbrojtje mjedisi1".

  15. DETERMINATION OF COPPER AND ZINC IN MINERAL WATERS BY ATOMIC ABSORPTION SPECTROPHOTOMETRY

    Directory of Open Access Journals (Sweden)

    Tatiana Mitina

    2011-12-01

    Full Text Available The content of copper and zinc in mineral waters were determined by atomic spectroscopy with preliminary extraction of metals. Validation of the technique was carried out by the method of standard additions and proved the reliability of analytical data.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. Low resolution ultraviolet and optical spectrophotometry of symbiotic stars

    Science.gov (United States)

    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.

  19. The expected performance of stellar parametrization with Gaia spectrophotometry

    CERN Document Server

    Liu, C; Sordo, R; Vallenari, A; Borrachero, R; Luri, X; Sartoretti, P

    2012-01-01

    Gaia will obtain astrometry and spectrophotometry for essentially all sources in the sky down to a broad band magnitude limit of G=20, an expected yield of 10^9 stars. Its main scientific objective is to reveal the formation and evolution of our Galaxy through chemo-dynamical analysis. In addition to inferring positions, parallaxes and proper motions from the astrometry, we must also infer the astrophysical parameters of the stars from the spectrophotometry, the BP/RP spectrum. Here we investigate the performance of three different algorithms (SVM, ILIUM, Aeneas) for estimating the effective temperature, line-of-sight interstellar extinction, metallicity and surface gravity of A-M stars over a wide range of these parameters and over the full magnitude range Gaia will observe (G=6-20mag). One of the algorithms, Aeneas, infers the posterior probability density function over all parameters, and can optionally take into account the parallax and the Hertzsprung-Russell diagram to improve the estimates. For all alg...

  20. Method development for the determination of fluorine in water samples via the molecular absorption of strontium monofluoride formed in an electrothermal atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Ozbek, Nil, E-mail: nil.ozbek@itu.edu.tr; Akman, Suleyman, E-mail: akmans@itu.edu.tr

    2012-03-15

    The presence of fluorine (F) was detected via the rotational molecular absorption line of diatomic strontium-monofluoride (SrF) generated in the gas phase at 651.187 nm using high-resolution continuum source electrothermal atomic absorption spectrometry. Upon the addition of excess strontium (Sr) as the nitrate, the fluorine in the sample was converted to SrF in the gas phase of a graphite furnace. The effects on the accuracy, precision and sensitivity of variables such as the SrF wavelength, graphite furnace program, amount of Sr, coating of the graphite tube and platform with Zr and Ir and the use of a modifier were investigated and optimized. It was determined that there was no need to use a modifier or to cover the platform/tubes with Zr or Ir. Fluorine concentrations in various water samples (certified waste water, tap water, drinking water and mineral water) were determined using 20 {mu}g of Sr as the molecule-forming reagent and applying a maximum pyrolysis temperature of 800 Degree-Sign C and a molecule-forming temperature of 2200 Degree-Sign C with a heating rate of 2000 Degree-Sign C s{sup -1}. Good linearity was maintained up to 0.1 {mu}g of F. The accuracy and precision of the method were tested by analyzing certified reference wastewater. The results were in good agreement with certified values, and the precision was satisfactory (RSD < 10%). The limit of detection and the characteristic mass for the method were 0.36 ng and 0.55 ng, respectively. Finally, the fluorine concentrations in several drinking water and mineral water samples taken from the market were determined. The results were in good agreement with the values supplied by the producers. No significant differences were found between the results from the linear calibration and standard addition techniques. The method was determined to be simple, fast, accurate and sensitive. - Highlights: Black-Right-Pointing-Pointer F is determined via MAS of SrF at 651.187 nm using HR-CS-ET AAS. Black

  1. Lunar absorption spectrophotometer for measuring atmospheric water vapor.

    Science.gov (United States)

    Querel, Richard R; Naylor, David A

    2011-02-01

    A novel instrument has been designed to measure the nighttime atmospheric water vapor column abundance by near-infrared absorption spectrophotometry of the Moon. The instrument provides a simple, effective, portable, and inexpensive means of rapidly measuring the water vapor content along the lunar line of sight. Moreover, the instrument is relatively insensitive to the atmospheric model used and, thus, serves to provide an independent calibration for other measures of precipitable water vapor from both ground- and space-based platforms.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Huo, Jing'e; Li, Quanmin

    2012-02-15

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

  4. Analysis of Astaxathin by Spectrophotometry%分光光度法测定虾青素

    Institute of Scientific and Technical Information of China (English)

    张泳; 厉妙沙; 吴嘉圣

    2015-01-01

    Establish a rapid determination of an analytical assay of astaxathin were desgned from chemi-cal synthesis by spectrophotometry. Using chloroform as extraction solution treated by hydroquinone,under 489nm wavelength determination of absorption.The spectrophotometric method of standard curve regression coefficient is 0.9999. the relative standard deviation is 0.36%, the standard addition recovery is 99.8%~102.5%, show that the analysis method of high accuracy, good repeatability, and is simple, rapid, and can be used as an enterprise with the determination of astaxanthin in mass production.%建立一种快速测定化学合成虾青素含量的分光光度分析方法。采用经氢醌处理的三氯甲烷做为提取溶液,在489 nm波长下测定吸光度,该分光光度法的标准曲线回归系数是0.9999,相对标准偏差为0.36%,加标回收率为99.8%~102.5%,表明该分析方法准确性高、重复性好,且简便、快速,可以作为企业大批量生产中虾青素的测定方法。

  5. Absorption intestinale des vitamines liposolubles

    OpenAIRE

    Reboul Emmanuelle

    2011-01-01

    The molecular mechanisms of fat-soluble vitamin intestinal absorption remain partly unknown, despite the fact that a better understanding of this process would certainly allow to improve their bioavailability. If their digestion-absorption process follows the fate of lipids globally, the recent discovery of membranes proteins involved in their absorption questioned the established dogmas. These new data should be taken into account to avoid dietary or drug interactions that may limit some fat...

  6. Absorption intestinale des vitamines liposolubles

    Directory of Open Access Journals (Sweden)

    Reboul Emmanuelle

    2011-03-01

    Full Text Available The molecular mechanisms of fat-soluble vitamin intestinal absorption remain partly unknown, despite the fact that a better understanding of this process would certainly allow to improve their bioavailability. If their digestion-absorption process follows the fate of lipids globally, the recent discovery of membranes proteins involved in their absorption questioned the established dogmas. These new data should be taken into account to avoid dietary or drug interactions that may limit some fatsoluble vitamin bioavailability.

  7. Analysis of pharmaceutical creams: a useful approach based on solid-phase extraction (SPE) and UV spectrophotometry.

    Science.gov (United States)

    Bonazzi, D; Andrisano, V; Gatti, R; Cavrini, V

    1995-10-01

    Solid-phase extraction (SPE) using C-18, diol and ion-exchange sorbents followed by UV spectrophotometric (conventional and derivative mode) assay was applied to the analysis of basic, acidic and neutral drugs commercially available in creams. A representative set of drugs (promethazine, chlorhexidine, benzydamine, ketoprofen, ibuprofen, fentiazac, piroxicam, fluorouracil, crotamiton and hydrocortisone acetate) was selected, and for each drug the appropriate SPE conditions (adsorption, washing and elution) were investigated to obtain a practical and reliable sample clean-up. It was shown that the developed SPE procedures were capable of removing interfering cream components (excipients including preservatives) allowing accurate spectrophotometric analyses to be performed. In some applications, derivative spectrophotometry was advantageous over the conventional absorption mode with respect to higher selectivity and versatility.

  8. Simultaneous quantitative resolution of atorvastatin calcium and fenofibrate in pharmaceutical preparation by using derivative ratio spectrophotometry and chemometric calibrations.

    Science.gov (United States)

    Nagaraj; Vipul, Kalamkar; Rajshree, Mashru

    2007-04-01

    In the present work, five different spectrophotometric techniques for simultaneous determination of formulations containing atorvastatin calcium (ATOR) and fenofibrate (FENO) in various combinations are described. In ratio spectra derivative spectrophotometry, analytical signals were measured at wavelengths corresponding to either maximums or minimums for both drugs in first derivative spectra of ratio spectra obtained by using either spectrum as divisor. For the remaining four methods using chemometric techniques, namely, classical least squares (CLS), inverse least squares (ILS), principal component regression (PCR) and partial least squares (PLS), the calibrations were constructed by using the absorption data matrix corresponding to the concentration data matrix, with measurements in the range of 231 - 310 nm (Deltalambda = 1 nm) in their zero-order spectra. The linearity range was found to be 4 - 22 and 2 - 20 microg/ml for ATOR and FENO, respectively. The validity of the proposed methods was successfully assessed for analyses of both drugs in laboratory-prepared mixtures and in commercial tablet formulations.

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

    Science.gov (United States)

    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%.

  10. A simple and fast method for assessment of the nitrogen–phosphorus–potassium rating of fertilizers using high-resolution continuum source atomic and molecular absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bechlin, Marcos André; Fortunato, Felipe Manfroi; Moutinho da Silva, Ricardo; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta, E-mail: anchieta@iq.unesp.br

    2014-11-01

    The determination of N, P, and K in fertilizers by high-resolution continuum source flame atomic and molecular absorption spectrometry is proposed. Under optimized conditions, measurements of the diatomic molecules NO and PO at 215.360 and 247.620 nm, respectively, and K using the wing of the alternative line at 404.722 nm allowed calibration curves to be constructed in the ranges 500–5000 mg L{sup −1} N (r = 0.9994), 100–2000 mg L{sup −1} P (r = 0.9946), and 100–2500 mg L{sup −1} K (r = 0.9995). Commercial fertilizers were analyzed by the proposed method and the concentrations of N, P, and K were found to be in agreement with those obtained by Kjeldahl, spectrophotometric, and flame atomic emission spectrometry methods, respectively, at a 95% confidence level (paired t-test). A phosphate rock certified reference material (CRM) was analyzed and the results for P and K were in agreement with the reference values. Recoveries from spiked CRM were in the ranges 97–105% (NO{sub 3}{sup −}-N), 95–103% (NH{sub 4}{sup +}-N), 93–103% (urea-N), 99–108% (P), and 99–102% (K). The relative standard deviations (n = 12) for N, P, and K were 6, 4, and 2%, respectively. - Highlights: • A single technique is proposed to analyze NPK fertilizer. • HR-CS FAAS is proposed for the first time for N, P and K determination in fertilizers. • The method employs the same sample preparation and dilution for the three analytes. • Addition of H{sub 2}O{sub 2} allows analysis of fertilizers with different nitrogen species. • Proposal provides advantages over traditional methods in terms of cost and time.

  11. Assessing the risk of pH-dependent absorption for new molecular entities: a novel in vitro dissolution test, physicochemical analysis, and risk assessment strategy.

    Science.gov (United States)

    Mathias, Neil R; Xu, Yan; Patel, Dhaval; Grass, Michael; Caldwell, Brett; Jager, Casey; Mullin, Jim; Hansen, Luke; Crison, John; Saari, Amy; Gesenberg, Christoph; Morrison, John; Vig, Balvinder; Raghavan, Krishnaswamy

    2013-11-04

    Weak base therapeutic agents can show reduced absorption or large pharmacokinetic variability when coadministered with pH-modifying agents, or in achlorhydria disease states, due to reduced dissolution rate and/or solubility at high gastric pH. This is often referred to as pH-effect. The goal of this study was to understand why some drugs exhibit a stronger pH-effect than others. To study this, an API-sparing, two-stage, in vitro microdissolution test was developed to generate drug dissolution, supersaturation, and precipitation kinetic data under conditions that mimic the dynamic pH changes in the gastrointestinal tract. In vitro dissolution was assessed for a chemically diverse set of compounds under high pH and low pH, analogous to elevated and normal gastric pH conditions observed in pH-modifier cotreated and untreated subjects, respectively. Represented as a ratio between the conditions, the in vitro pH-effect correlated linearly with clinical pH-effect based on the Cmax ratio and in a non-linear relationship based on AUC ratio. Additionally, several in silico approaches that use the in vitro dissolution data were found to be reasonably predictive of the clinical pH-effect. To explore the hypothesis that physicochemical properties are predictors of clinical pH-effect, statistical correlation analyses were conducted using linear sequential feature selection and partial least-squares regression. Physicochemical parameters did not show statistically significant linear correlations to clinical pH-effect for this data set, which highlights the complexity and poorly understood nature of the interplay between parameters. Finally, a strategy is proposed for implementation early in clinical development, to systematically assess the risk of clinical pH-effect for new molecular entities that integrates physicochemical analysis and in vitro, in vivo and in silico methods.

  12. Chemical Speciation of the System Cu(II-Indomethacin in Ethanol and Water by UV-Vis Spectrophotometry

    Directory of Open Access Journals (Sweden)

    Norma Rodríguez-Laguna

    2016-01-01

    Full Text Available It has been proposed that the metal-drug complexes could be in fact the active agents displaying therapeutic effects of drugs. The characterization of the global formation equilibrium of complexes formed between metal ions and species with biological activity such as nonsteroidal anti-inflammatory drugs provides essential information to understand the mechanism of action of drugs. Since equilibrium constants determine the relative predominance of species, they provide crucial information to identify what complexes are more likely to be present in the system being responsible for the therapeutic effects of the drug. In this paper, the systems formed between copper and Indomethacin of different concentrations in ethanol or water were studied by UV-Vis spectrophotometry. The stoichiometry of the complexes Cu(II–Indomethacin and their formation constants were investigated. Moreover, molecular structures of the Cu(II–Indomethacin complexes were explored by means of the molecular modeling within the frame of the density functional theory.

  13. The reaction of cardiovascular system and orbital vessels after THz irradiation of molecular spectrum of emission and absorption of 129.0 GHz atmospheric oxygen in healthy volunteers and in patients with involutional macular degeneration

    Directory of Open Access Journals (Sweden)

    Vyacheslav F. Kirichuk

    2013-11-01

    Full Text Available The study aims the influence of THz radiation on 129.0 GHz of atmospheric oxygen on blood pressure (BP and pulse, hemodynamic parameters of orbital arteries during the irradiation of biological active points of application in healthy volunteers and in patients with involutional macular degeneration (IMD. It had been noticed a decrease of systolic and diastolic components of arterial pressure and pulse; a normalization of systolic velocity of bloodstream (SVB and of resistance index (RI in orbital arteries in patients with IMD. The result of the research is: 1 the method of THz influence of on molecular spectrum of emission and absorption of 129.0 GHz atmospheric oxygen is safe and does not cause any negative side effects on common state in healthy volunteers and in patients with IMD; 2 single of THz influence of molecular spectrum of emission and absorption of 129.0 GHz atmospheric oxygen caused a statistical important improvement in vascular system of eyeball.

  14. Spectrophotometry of comets Giacobini-Zinner and Halley

    Science.gov (United States)

    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.

  15. 玻璃片—分光光度法测定玻璃中铁和亚铁%Determination of iron and ferrous in glass by sheet glass spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    刘小青; 谢峻林; 何峰; 方德

    2013-01-01

    利用紫外-可见分光光度计玻璃中三价铁含量与紫外吸收峰面积,二价铁含量与可见及近红外吸收峰面积的对应关系X射线荧光、湿化学—分光光度法和玻璃片—分光光度法相同玻璃中铁含量,玻璃片—分光光度法的准确性.结果显示,玻璃中三价铁含量和二价铁含量分别与单位厚度玻璃片在370~400 nm范围的紫外吸收峰面积和520~1i00 nm范围的可见及近红外吸收峰面积线性相关,可以用相应吸收峰面积计算玻璃中不同价态铁的含量.玻璃片—分光光度法的测试结果与X射线荧光和湿化学—分光光度法的测试结果相对误差均在士5%以内,利用玻璃片—分光光度法可以准确测定玻璃中的铁和亚铁含量.%To investigate a new method of fast determination of iron contents and ferrous iron contents in glasses by sheet glass spectrophotometry,UV-Vis spectrophotometer and wet-chemical spectrophotometry were used to study the relationships between ferric iron content and its UV absorption peak area,and between ferrous iron content and its Vis-NIR absorption peak area in unit thickness sheet glass.By using fluorescent X-ray spectrometry,wet-chemical spectrophotometry and sheet glass spectrophotometry methods on the determination of iron contents in identical glasses,the accuracy of sheet glass spectrophotometry was studied.The results showed that ferric iron contents in glasses have linear correlation with UV absorption peak areas of unit thickness sheet glasses in 370-400 nm region,ferrous iron contents in glasses have linear correlation with Vis-NIR absorption peak areas of unit thickness sheet glasses in 520-1100 nm region,the contents of different charge irons in glasses can be determinated by calculating corresponding absorption peak areas.The relative errors of determination results between sheet glass spectrophotometry and fluorescent X-ray spectrometry,and between sheet glass spectrophotometry and wet

  16. Spectrophotometry of Artemisia tridentata to quantitatively determine subspecies

    Science.gov (United States)

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

    2017-01-01

    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.

  17. Análise multicomponente simultânea por espectrofotometria de absorção molecular UV-VIS

    Directory of Open Access Journals (Sweden)

    Saldanha Teresa Cristina B.

    1999-01-01

    Full Text Available This review presents the evolution of simultaneous multicomponent analysis by absorption spectrophotometry in the ultraviolet and visual regions in terms of some qualitative and quantitative analysis techniques, otimization methods, as well as applications and modern trends.

  18. Análise multicomponente simultânea por espectrofotometria de absorção molecular UV-VIS

    OpenAIRE

    Saldanha Teresa Cristina B.; Araújo Mário César U. de; Barros Neto Benício de

    1999-01-01

    This review presents the evolution of simultaneous multicomponent analysis by absorption spectrophotometry in the ultraviolet and visual regions in terms of some qualitative and quantitative analysis techniques, otimization methods, as well as applications and modern trends.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hackmann, E.R.M.; Santos Gianotto, E.A. dos; Miritello Santoro, M.I.R. (Universidade de Sao Paulo (Brazil))

    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%. 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.

  20. Speciation and thermodynamic properties of zinc in sulfur-rich hydrothermal fluids: Insights from ab initio molecular dynamics simulations and X-ray absorption spectroscopy

    Science.gov (United States)

    Mei, Yuan; Etschmann, Barbara; Liu, Weihua; Sherman, David M.; Testemale, Denis; Brugger, Joël

    2016-04-01

    Chlorine and sulfur are the main elements involved in the complexing of metals in ore-forming fluids. The nature and thermodynamic properties of the Zn(II)-Cl complexes have been investigated by previous experimental and theoretical studies and are now well established up to high temperatures (600 °C). In contrast, the role of bisulfide complexes for zinc speciation in sulfur-bearing fluids remains poorly known, and a better understanding of Zn(II)-HS complexation is required for modeling zinc transport in magmatic and metamorphic fluids and for optimizing the hydrometallurgical processing of sulfide ores. We have conducted ab initio molecular dynamics (MD) simulations to calculate the speciation of Zn(II)-HS complexes from ambient to hydrothermal-magmatic conditions (25-600 °C, up to 2000 bar). These theoretical calculations were complemented by X-ray absorption spectroscopy (XAS) measurements of Zn(II) in HS--rich solutions at 200-500 °C and 600-1000 bar. The speciation and geometrical properties predicted by the ab initio MD simulations and the in situ XAS data are in excellent agreement. Upon heating from room temperature to 250 °C, Zn(II) speciation in HS--rich solutions shows a transition from the sixfold octahedral hexaaquo complex [Zn(H2O)6]2+ to fourfold tetrahedral [Zn(HS)n(H2O)4-n]2-n complexes (n = 1-4). Ab initio MD simulations also show that at temperatures > 250 °C, the threefold trigonal-planar [Zn(HS)3]- complex becomes increasingly stable, and predominates in S-rich solutions; in contrast, chloro-complexes display a tetrahedral geometry at 25-500 °C, while trigonal planar ZnCl3- predominates at temperatures > 500 °C. The stability constants of Zn(II)-HS complexes were calculated by thermodynamic integration of constrained ab initio MD simulations at 200, 350 and 600 °C. The stability constants generated from this study predict that zinc can be transported by HS- at high temperature in reduced, neutral to alkaline solutions, while Zn

  1. Biphasic drug absorption from the epidural space of the dog may limit the utility of a slow release medium molecular weight hyaluronic acid-lidocaine ionic complex formulation.

    Science.gov (United States)

    Doherty, M M; Hughes, P J; Charman, S A; Brock, K V; Korszniak, N V; Charman, W N

    1996-12-01

    Previous epidural studies conducted in rabbits have described a viscous lidocaine-hyaluronate formulation (L-HA) that prolonged the duration of sensory blockade twofold and decreased the rate of drug absorption fourfold relative to a solution formulation. As further evaluation of the L-HA formulation required studies in a larger animal that more closely reflected the characteristic absorption kinetics observed in humans, a conscious dog model was used to functionally and kinetically evaluate the viscous formulation relative to lidocaine solution. In terms of the measured pharmacodynamic end point (loss of weight-bearing ability in hind legs), epidural administration of the L-HA formulation did not prolong the duration of action relative to lidocaine solution in spite of a markedly altered pharmacokinetic profile. For example, administration of L-HA reduced the mean plasma lidocaine Cmax value approximately 50% and increased the Tmax value approximately fivefold relative to lidocaine solution. However, the viscous L-HA formulation did cause a significant prolongation in the latency of onset (P lidocaine solution. The dog exhibited "flip-flop" pharmacokinetics and absorption was biphasic after epidural administration of lidocaine solution (apparent t1/2 of the fast and slow absorption phases were 4 min and 131 min, respectively). The L-HA formulation markedly altered the absorption kinetics such that a single, slow absorption phase was evident (apparent t1/2 of 56 min), although this rate was more rapid than the slow phase observed after lidocaine solution. It is possible that the inability of the hyaluronate-based formulation to further reduce the magnitude of the slow absorption phase resulted in the failure to prolong the duration of action. These data highlight the need to carefully consider the absorption kinetics and pharmacokinetic characteristics of the animal models chosen to evaluate new formulation of epidurally administered local anesthetics.

  2. Magnetic Resonance Cell-Tracking Studies: Spectrophotometry-Based Method for the Quantification of Cellular Iron Content after Loading with Superparamagnetic Iron Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ingrid Böhm

    2011-07-01

    Full Text Available 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 Λpeak was determined at A720nm (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 T2-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.

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

    Directory of Open Access Journals (Sweden)

    Butnariu Monica

    2012-04-01

    Full Text Available Abstract 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.

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

    Science.gov (United States)

    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

  5. Study on New Sensitive Method of Determination of Phosphorus by Solid Phase Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The use of solid phase spectrophotometry for the determination of trace phosphorus in the system of phosphomolybdate-fructose is described. The adsorption of the system on anion-exchange resin is reported.

  6. Determination of Trace Amount of Yttrium with Bromopyrogallol Red by Solid-phase Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A simple and sensitive method for the determination of trace amount of yttrium by solid-phase spectrophotometry has been studied. Yttrium can form a 1∶1 complex with bromopyrogallol red (BPR) on resin, which was determined directly at 605 nm, pH=6.5. It has a highly sensitivity ( = 6.3€?06) which is 300-fold higher than the corresponding spectrophotometry in solution. The method was applied to the determination of yttrium in churchite.

  7. Liquid standards utilization for metrological ensuring of spectrophotometry

    Science.gov (United States)

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

    1993-12-01

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

  8. Aluminum complexation by catechol as determined by ultraviolet spectrophotometry

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-03-01

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

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

    Science.gov (United States)

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

    2009-01-15

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

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

    Science.gov (United States)

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

    1981-01-01

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

  11. Diagnosis of Smith-Lemli-Opitz syndrome by ultraviolet spectrophotometry

    Directory of Open Access Journals (Sweden)

    F.B. Scalco

    2003-10-01

    Full Text Available Smith-Lemli-Opitz syndrome (SLOS is an autosomal recessive disorder due to an inborn error of cholesterol metabolism, characterized by congenital malformations, dysmorphism of multiple organs, mental retardation and delayed neuropsychomotor development resulting from cholesterol biosynthesis deficiency. A defect in 3ß-hydroxysteroid-delta7-reductase (delta7-sterol-reductase, responsible for the conversion of 7-dehydrocholesterol (7-DHC to cholesterol, causes an increase in 7-DHC and frequently reduces plasma cholesterol levels. The clinical diagnosis of SLOS cannot always be conclusive because of the remarkable variability of clinical expression of the disorder. Thus, confirmation by the measurement of plasma 7-DHC levels is needed. In the present study, we used a simple, fast, and selective method based on ultraviolet spectrophotometry to measure 7-DHC in order to diagnose SLOS. 7-DHC was extracted serially from 200 µl plasma with ethanol and n-hexane and the absorbance at 234 and 282 nm was determined. The method was applied to negative control plasma samples from 23 normal individuals and from 6 cases of suspected SLOS. The method was adequate and reliable and 2 SLOS cases were diagnosed.

  12. The synthesis and UV-VIS-NIR spectrophotometry of Dmit complexes%Dmit配合物的合成及其UV-VIS-NIR光谱

    Institute of Scientific and Technical Information of China (English)

    许文

    2012-01-01

    选用二硫烯类配体Dmit首次合成了新配合物(MePyMe)2[Ni (dmit)2]和(MePyMe)[Ni( dmit)2],测定了二者在乙腈溶剂中的UV-VIS-NIR吸收光谱;并在I-3存在时测定了(MePyMe)2[Ni(dmit)2]在乙腈溶剂中的动态UV-VIS-NIR吸收光谱,对某些光谱峰做了指认.结果表明:阴离子的不同氧化态对吸收光谱影响较大,[Ni(dmit)2]2-无NIR吸收,而[Ni(dmit)2] -有强烈的NIR吸收,因此,后者[Ni(dmit)2] -可作为NIR激光染料.其NIR吸收应源自[Ni (dmit)2] -的小的LUMO与HOMO的π→π*跃迁.%Two new Dmit complexes, ( MePyMe ) 2 [ Ni ( dmit) 2 ] and ( MePyMe ) [ Ni ( drait) 2 ], have been prepared and their UV-VIS-NIR spectrophotometry in CH3CN have also been measured. During the course of oxidation of ( MePyMe ) 2 [ Ni ( dmit) 2 ] , by using I3- , UV-VIS-NIR spectrophotometry have been monitored online. Different valence states of anion have shown great influence on spectrum absorption. [Ni(dmit)2]2- has no NIR absorption, while [Ni(dmit)2] ~ exhibits a strong NIR absorption. So, [Ni(dmit)2] - can be to applied as NIR laser dyes. The NIR absorption is assigned to be Π->π* transition between LUMO and HOMO of [Ni(dmit)2] -.

  13. Influence of phosphorus and calcium on flame atomic absorption spectrophotometric determination of lead in canned fish products.

    Science.gov (United States)

    Serra, T M; Serrano, J F

    1984-01-01

    Lead was determined in the presence of whole multiples of the P/Ca ratio found in Portuguese canned fish by flame atomic absorption spectrophotometry with and without using an ashing aid. Under our experimental conditions, use of the ashing aid eliminates P and Ca interference. Results with real samples, spiked with 1, 2, 3, and 4 ppm lead, are presented and statistically treated.

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

    Science.gov (United States)

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

    2016-11-01

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

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

    Science.gov (United States)

    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.

  16. Nickel(II) Complexation with Nitrate in Dry [C4mim][Tf2N] Ionic Liquid: A Spectroscopic, Microcalorimetric, and Molecular Dynamics Study.

    Science.gov (United States)

    Melchior, Andrea; Gaillard, Clotilde; Gràcia Lanas, Sara; Tolazzi, Marilena; Billard, Isabelle; Georg, Sylvia; Sarrasin, Lola; Boltoeva, Maria

    2016-04-04

    The complex formation of nitrate ions with nickel(II) in dry [C4mim][Tf2N] ionic liquid (IL) was investigated by means of UV-visible spectrophotometry, isothermal titration calorimetry (ITC), extended X-ray absorption fine structure spectroscopy (EXAFS), and molecular dynamics (MD) simulations. EXAFS spectroscopy and MD simulations show that the solvated Ni(II) cation is initially coordinated by the oxygens of the [Tf2N](-) anion of IL, which can behave either as mono- or bidentate. Spectroscopic and thermodynamic data show that Ni(II) is able to form up to three stable mononuclear complexes with nitrate in this solvent. The stability constants for Ni(NO3)j complexes (j = 1-3) calculated from spectrophotometry and ITC experiments decrease in the order log K1 > log K2 > log K3. The formation of the first two species is enthalpy-driven, while the third species is entropy-stabilized. The UV-vis spectra of solutions containing different nitrate/Ni(II) ratios show that the metal ion retains the six-coordinate geometry. Furthermore, the EXAFS evidences that nitrate is always bidentate. Molecular dynamics simulations show that the [Tf2N](-) anions bind Ni(II) through the sulfonyl oxygen atoms and can coordinate either as monodentate or chelate. The analysis of the MD data shows that introduction of nitrates in the first coordination sphere of the metal ion results in remarkable structural rearrangement of the ionic liquid.

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

    Science.gov (United States)

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

    2013-01-01

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

  18. Speciation of Fe(II) and Fe(III) by the modified ferrozine method, FIA-spectrophotometry, and flame AAS after cloud-point extraction

    Energy Technology Data Exchange (ETDEWEB)

    Giokas, Dimosthenis L.; Paleologos, Evangelos K.; Karayannis, Miltiades I. [Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina (Greece)

    2002-07-01

    A method has been developed for the simultaneous determination of traces of Fe(III) and Fe(II) in water by on-line coupling of spectrophotometry with flame atomic absorption spectrometry (FAAS). The method involves cloud-point extraction (CPE) of both species with ammonium pyrrolidinecarbodithioate (APDC) under standard conditions, which facilitates the in situ complexation and extraction of both species. Differentiation of the oxidation states of iron is achieved by using mathematical equations to overcome the interference of Fe(III) in the spectrophotometric determination of Fe(II) when they are both present in the same solution. In this manner the time-consuming and labor-intensive steps of preoxidation of Fe(II) or reduction of Fe(III) are eliminated. By preconcentrating a 10-mL sample solution detection limits as low as 7 {mu}g L{sup -1}, were obtained after a single-step extraction procedure. The relative standard deviation (n=4, 30 {mu}g L{sup -1}) was 2.6 % and 1.8 % for spectrophotometry and FAAS, respectively. Recoveries in the range of 96-105 % were obtained by analysis of spiked real samples. The method was further verified by analyzing a certified reference material (IMEP-9); for this the recovery was 98.5 %. (orig.)

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

    Science.gov (United States)

    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.

  20. Methane absorption variations in the spectrum of Pluto

    Energy Technology Data Exchange (ETDEWEB)

    Buie, M.W.; Fink, U.

    1987-06-01

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

  1. C3 and infrared spectrophotometry of Y Canum Venaticorum

    Science.gov (United States)

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

    1978-01-01

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

  2. 3 micron spectrophotometry of Comet Halley - Evidence for water ice

    Science.gov (United States)

    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. Spectral lineshapes of collision-induced absorption (CIA) and collision-induced light scattering (CILS) for molecular nitrogen using isotropic intermolecular potential. New insights and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    El-Kader, M.S.A., E-mail: mohamedsay68@hotmail.com [Department of Engineering Mathematics and Physics, Faculty of Engineering, Giza 12211 (Egypt); Mostafa, S.I. [Department of Engineering Mathematics and Physics, Faculty of Engineering, Giza 12211 (Egypt); Bancewicz, T. [Faculty of Physics, Department of Nonlinear Optics, Umultowska 85, 61-614 Poznań (Poland); Maroulis, G. [Department of Chemistry, University of Patras, GR-26500 Patras (Greece)

    2014-08-31

    Highlights: • We have determined an isotropic intermolecular potential for the interaction of nitrogen. • The thermophysical and transport properties are calculated for this gas. • We have adopted a model for the induced dipole moment μ(r) with adjustable parameters. • The induced trace polarizability model are constructed for scattering. • The quantum lineshapes of absorption and scattering are calculated. - Abstract: The rototranslational collision-induced absorption (CIA) at different temperatures and collision-induced light scattering (CILS) at room temperature of nitrogen gas are analyzed in terms of new isotropic intermolecular potential, multipole-induced dipole functions and interaction-induced pair polarizability models, using quantum spectral lineshape computations. The irreducible spherical form for the induced operator of light scattering mechanisms was determined. The high frequency wings are discussed in terms of the collision-induced rotational Rayleigh effect and estimates for the dipole–octopole polarizability E{sub 4}, is obtained and checked with the ab initio theoretical value. The quality of the present potential has been checked by comparing between calculated and experimental thermo-physical and transport properties over a wide temperature range, which are found to be in good agreement.

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

    Science.gov (United States)

    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.

  5. STUDY ON DETERMINATION OF TRACE Fe BY Fe(Ⅱ)-VA THIN LAYER RESIN PHASE SPECTROPHOTOMETRY

    Institute of Scientific and Technical Information of China (English)

    SONG Huanyu; YAN Yongsheng; WANG Yun

    2006-01-01

    A new method for the determination of Fe by thin layer resin phase spectrophotometry in alkali condition was reported. The complex anion formed by Fe(Ⅱ) and VA was absorbed on the 717#resin and Fe was determined by making thin layer. This method had a high sensitivity (ε620=3.0×105 L/mol·cm), which was 15 times higher than that of liquid phase spectrophotometry. It had been proved a satisfactory precision (5.0μg Fe, n=6, RSD=1.8%). The trace Fe in natural water was determined and the recovery was 97%.

  6. Circadian Regulation of Macronutrient Absorption.

    Science.gov (United States)

    Hussain, M Mahmood; Pan, Xiaoyue

    2015-12-01

    Various intestinal functions exhibit circadian rhythmicity. Disruptions in these rhythms as in shift workers and transcontinental travelers are associated with intestinal discomfort. Circadian rhythms are controlled at the molecular level by core clock and clock-controlled genes. These clock genes are expressed in intestinal cells, suggesting that they might participate in the circadian regulation of intestinal functions. A major function of the intestine is nutrient absorption. Here, we will review absorption of proteins, carbohydrates, and lipids and circadian regulation of various transporters involved in their absorption. A better understanding of circadian regulation of intestinal absorption might help control several metabolic disorders and attenuate intestinal discomfort associated with disruptions in sleep-wake cycles.

  7. Spectral lineshapes of collision-induced absorption (CIA) and collision-induced light scattering (CILS) for molecular nitrogen using isotropic intermolecular potential. New insights and perspectives

    Science.gov (United States)

    El-Kader, M. S. A.; Mostafa, S. I.; Bancewicz, T.; Maroulis, G.

    2014-08-01

    The rototranslational collision-induced absorption (CIA) at different temperatures and collision-induced light scattering (CILS) at room temperature of nitrogen gas are analyzed in terms of new isotropic intermolecular potential, multipole-induced dipole functions and interaction-induced pair polarizability models, using quantum spectral lineshape computations. The irreducible spherical form for the induced operator of light scattering mechanisms was determined. The high frequency wings are discussed in terms of the collision-induced rotational Rayleigh effect and estimates for the dipole-octopole polarizability E4, is obtained and checked with the ab initio theoretical value. The quality of the present potential has been checked by comparing between calculated and experimental thermo-physical and transport properties over a wide temperature range, which are found to be in good agreement.

  8. Infrared absorption by molecular gases as a probe of nanoporous silica xerogel and molecule-surface collisions: Low-pressure results

    Science.gov (United States)

    Vander Auwera, J.; Ngo, N. H.; El Hamzaoui, H.; Capoen, B.; Bouazaoui, M.; Ausset, P.; Boulet, C.; Hartmann, J.-M.

    2013-10-01

    Transmission spectra of gases confined (but not adsorbed) within the pores of a 1.4-cm-thick silica xerogel sample have been recorded between 2.5 and 5 μm using a high-resolution Fourier transform spectrometer. This was done for pure CO, CO2, N2O, H2O, and CH4 at room temperature and pressures of a few hectopascals. Least-squares fits of measured absorption lines provide the optical-path lengths within the confined (LC) and free (LF) gas inside the absorption cell and the half width at half maximum ΓC of the lines of the confined gases. The values of LC and LF retrieved using numerous transitions of all studied species are very consistent. Furthermore, LC is in satisfactory agreement with values obtained from independent measurements, thus showing that reliable information on the open porosity volume can be retrieved from an optical experiment. The values of ΓC, here resulting from collisions of the molecules with the inner surfaces of the xerogel pores, are practically independent of the line for each gas and inversely proportional to the square root of the probed-molecule molar mass. This is a strong indication that, for the studied transitions, a single collision of a molecule with a pore surface is sufficient to change its rotational state. A previously proposed simple model, used for the prediction of the line shape, leads to satisfactory agreement with the observations. It also enables a determination of the average pore size, bringing information complementary to that obtained from nitrogen adsorption porosimetry.

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

    Science.gov (United States)

    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.

  10. Determination of fluoride content in toothpaste using spectrophotometry

    Directory of Open Access Journals (Sweden)

    Susanti Pudji Hastuti

    2013-09-01

    Full Text Available Background: Intake excessive fluoride in children’s teeth are generally marked with white and brown patches. Excessive fluoride of more than 4.0 mg/L can cause a person suffering from poisoning, fragility of the bones (osteoporosis, liver and kidney damage. Knowledge about the spectrophotometry for determination method of fluoride content in commercially available toothpaste is very few. Purpose: The purposes of study were to examine the suitable method for fluoride extraction and to determine out the accuracy, precision, linearity, and stability of the measurement method of fluoride content in toothpaste. Methods: The suitable F extraction method was determined by the comparison among 3 methods of extraction; e.g. the dried samples were immersed in (1 distilled water, (2 96% HCl, and (3 96% HNO3; and the validation methods of measurement were the maximum wavelength, standart curve, accuracy test, precision test, and stability test. Results: Result showed that the fluoride extraction by using the concentrated HNO3 was found to have the highest levels of fluoride, followed by hydrochloric acid dissolution (HCl and distilled water, while the method of validation showed that SPADNS revealed the acceptable accuracy. Precision has the RSD ≤ 2.00%. Furthermore the stability test result showed that the measurement of fluoride less than 2 hours was still reliable. Conclusion: The study suggested that the best result of fluoride extraction from toothpaste could be gained by using concentrate HNO3, and the spectrophotometer (UV-Vis Mini Shimadzu U-1240 and SPADNS have the acceptable accuracy.Latar Belakang: Pemasukan fluoride yang berlebihan pada gigi anak ditandai dengan bercak putih dan coklat. Fluoride lebih dari 4.0 mg / L dapat menyebabkan seseorang menderita keracunan , kerapuhan tulang (osteoporosis, kerusakan hati dan ginjal. Pengetahuan tentang spektrofotometri untuk metode penentuan kadar fluoride dalam pasta gigi yang tersedia secara

  11. Near-Infrared Spectrophotometry of Phobos and Deimos

    Science.gov (United States)

    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.

  12. Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

    NARCIS (Netherlands)

    M.R. Germans; P.C. de Witt Hamer; L.J. van Boven; K.A.H. Zwinderman; G.J. Bouma

    2010-01-01

    (1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of

  13. High resolution spectrophotometry for identification of chlorine dioxide in concentrated chlorine solutions.

    Science.gov (United States)

    Gauw, R D; Emmert, G L; Bubnis, B; Gordon, G

    1999-12-06

    Electrolyzed salt brine generators hold great promise for water disinfection in small communities and remote locations. Electrolysis cell liquors have been reported to contain chlorine, chlorine dioxide and ozone. High resolution spectrophotometry was used to observe the presence (or absence) of a unique spectral absorbance pattern present in solutions containing 1-2 mg/l chlorine dioxide.

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

    Science.gov (United States)

    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.…

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

    Science.gov (United States)

    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.…

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

    Science.gov (United States)

    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.

  17. Kombineret laser Doppler flowmetri og spectrophotometri som metode til vurdering af mikrocirculation

    DEFF Research Database (Denmark)

    Berggren Olsen, Mette; Sørensen, Hanne Birke; Houlind, Kim Christian

    Kombineret laser Doppler flowmetri og spectrophotometri som metode til vurdering af mikrocirculation Berggren, MB, reservelæge, Karkirurgisk Afdeling, Kolding, mette.marie.berggren.olsen@slb.regionsyddanmark.dk; Houlind, K, lektor, afdelingslæge, Ph.d., Karkirurgisk afdeling, Kolding, kim...

  18. Structure of Liquid Aluminum and Hydrogen Absorption

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; DAI Yongbing; WANG Jun; SHU Da; SUN Baode

    2011-01-01

    The hydrogen content in aluminum melts at different temperature was detected. The structure in aluminum melts was investigated by molecular dynamics simulation. The first peak position of pair correlation function, atomic coordination number and viscosity of aluminum melts were calculated and they changed abnormally in the same temperature range. The mechanism of hydrogen absorption has been discussed. From molecular dynamics calculations, the interdependence between melt structural properties and hydrogen absorption were obtained.

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

    Science.gov (United States)

    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.

  20. 大孔吸附树脂纯化黄精小分子糖的工艺研究%Purification of Low Molecular Weight Saccharide in Rhizoma Polygonati by Macroorous Absorption Resins

    Institute of Scientific and Technical Information of China (English)

    李晓坤; 董晶晶; 贺海花; 杨云

    2011-01-01

    Objective: To study the optimal conditions and parameters of purifying lnw molecular weight saccharide in Rhizoma polygonati with macroporous resins. Method; With the yield and purily as the indices,the absorption characteristics of four resins for low molecular weight saccharide purification were compared. The optimal conditions of the; purification technology were investigated. Result; The AB-8 resin was the best of the four resins and the optimum conditions were the following;solution concentration of 36. 32 mg·ml-1, sample volume of 4 times of resin volume, eluting cubage of 8 times of resin volume, distilled water as eluling solvent with eluting rate of 1.0 ml·min-1. The yield was 97. 56% ,and the purity reached 90. 93%. Conclusion: The process of macroporous absorption resins to purify low molecular weight saccharide is simple,feasible and suitable for industrial production.%目的:研究大孔树脂吸附纯化黄精小分子糖的最佳工艺条件及参数.方法:以小分子糖保留率和纯度为考察指标,比较四种大孔树脂对黄精小分子糖的吸附性能,考察上样浓度、上样量、洗脱流速和洗脱剂用量等因素对优选树脂纯化工艺的影响,确定最佳工艺参数.结果:最佳工艺条件为选用AB-8大孔吸附树脂,上样浓度36.32 mg·ml-1,最大上样量4倍柱床体积,以蒸馏水8倍柱床体积洗脱,洗脱流速为1.0 ml·min-1.通过本工艺纯化的黄精小分子糖保留率达97.56%,纯度达90.93%.结论:大孔吸附树脂对黄精小分子糖有较好的纯化作用,该工艺简单可行,适合干工业化生产.

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

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

    2014-04-01

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

  4. Evaluation of the use of partition coefficients and molecular surface properties as predictors of drug absorption: a provisional biopharmaceutical classification of the list of national essential medi

    Directory of Open Access Journals (Sweden)

    NU Rahman

    2011-05-01

    Full Text Available Background and the purpose of the study: Partition coefficients (log D and log P and molecular surface area (PSA are potential predictors of the intestinal permeability of drugs. The aim of this investigation was to evaluate and compare these intestinal permeability indicators.   Methods: Aqueous solubility data were obtained from literature or calculated using ACD/Labs and ALOGPS. Permeability data were predicted based on log P, log D at pH 6.0 (log D6.0, and PSA.  Results: Metoprolol's log P, log D6.0 and a PSA of <65 Å correctly predicted 55.9%, 50.8% and 54.2% of permeability classes, respectively. Labetalol's log P, log D6.0, and PSA correctly predicted 54.2%, 64.4% and 61% of permeability classes, respectively. Log D6.0 correlated well (81% with Caco-2 permeability (Papp. Of the list of national essential medicines, 135 orally administered drugs were classified into biopharmaceutical classification system (BCS. Of these, 57 (42.2%, 28 (20.7%, 44 (32.6%, and 6 (4.4% were class I, II, III and IV respectively. Conclusion: Log D6.0 showed better prediction capability than log P. Metoprolol as permeability internal standard was more conservative than labetalol.

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

    Science.gov (United States)

    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.

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

    Institute of Scientific and Technical Information of China (English)

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

    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.

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

    Science.gov (United States)

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

    2013-05-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  9. VALIDATION METHOD OF ULTRAVIOLET SPECTROPHOTOMETRY DETERMINATION OF CONTENT IN AMBROXOL HCl TABLET

    OpenAIRE

    Tedy Kurniawan Bakri; Fathur Rahman Harun; Misrahanum .; Sadli .

    2015-01-01

    Ambroxol Hydrochloride (Ambroxol HCI) is one of mucolytic drugs that is commonly used to dilute thesecretion within the respiratory tract. This process is completed by lowering the viscosity of mucopolysaccharides, in which its characteristic which is mucolytic within the respiratory tract. This research aims to conduct a validation of the UV spectrophotometry method in determining the level of ambroxol HCI in tablets. This methos is also used to obtain the level of amboxol HCI in tablets tha...

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

    Science.gov (United States)

    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.

  11. New Approach to Detecting Phenoxyl Free Radicals Generated in Enzyme Reaction by Stopped-flow Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    Jing XU; Lan Hua ZHAO; Xin Guo WU; Hong Mei WANG; Ru Xiu CAI

    2006-01-01

    A highly sensitive stopped-flow spectrophotometry kinetic method was proposed forquantification phenoxyl radicals based on their accelerating effect on the oxidation of nicotinamide adenine dinucleotide (NADH). Phenoxyl radicals generated from as low as 1×10-8 mol/L 2,4-DCP can be readily detected with the proposed method and the detecting limit was 2.5×10-9mol/L.

  12. Determination of sucrose in isatis-soot granules by fourier transform infrared spectrophotometry%板蓝根颗粒中蔗糖含量的红外光谱法测定

    Institute of Scientific and Technical Information of China (English)

    梁奇峰; 温欣荣; 彭梦侠; 郑李纯

    2009-01-01

    A method for rapid quantitative determination of sucrose in isatis-root granules by Fourier Transform Infrared Spectrophotometry(FTIR) was developed. Potassium ferricyanide was chosen as an inside mark material because it has only one strong absorption peak at 2117cm-1 and the peak was chosen as its quantitative peak. The peak at 1283cm-1 is the characteristic absorption of sucrose and was chosen as the quantitative peak of sucrose. The ratio of the two absorbances is I=Ai/As.K3[Fe(CN)6] and sucrose were mixed according to a certain mass ratio m=mi/ms to prepare standard samples. The curve of m versus I is the quantitative working curve. The linear range for sucrose is 5.0~23.0mg/g,the recovery is in the range of 91%~103%,the relative standard deviation is less than 5%.

  13. 有机小分子溶液的红外吸收光谱的分子动力学模拟%Molecular Dynamics Simulation of Infrared Absorption Spectrum of Small Organic Molecular Liquids

    Institute of Scientific and Technical Information of China (English)

    丁杨; 毛英臣; 许佩军; 宛素钰; 刘锐; 李贝贝

    2013-01-01

      在 AMOEBA 极化力场下对水、甲醇和乙醇溶液的红外吸收光谱进行了分子动力学模拟,与传统力场的计算结果相比,更好地符合了实验结果。这主要由于考虑了电多极矩效应和诱导偶极矩效应, AMOEBA力场对静电相互作用进行精确的描述,进而较好地模拟了化学键的弯曲振动和伸缩振动。%The aim of this paper is to study the infrared spectrum of water, methanol and ethanol liquids by molecular dynamics simulations. Compared with the results by the simulations based on the traditional force fields, the results from the simulations with the AMOEBA polarizable force field are more in line with the experiment results. The critical reason is that AMOEBA force field describes the electrostatic interaction much better than others force fields due to the electric multipole effects and the induced dipole effect considered in the field, and makes the bend vibration and the stretch vibration of molecular bonds more accurately determined in the simulation.

  14. Highly Selective Derivative Spectrophotometry for Determination of Nickel Using 1-(2-Pyridylazo)-2-naphthol in Tween 80 Micellar Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Eskandari, Habibollah [University of Mohaghegh Ardebili, Ardebil (Iran, Islamic Republic of)

    2004-08-15

    A spectrophotometric and first derivative spectrophotometric method was developed in aquatic Tween 80 micellar solutions for selective determination of nickel without using any pre-separation step. 1-(2-Pyridylazo)- 2-naphthol (PAN), as a sensitive chromogenic complexing agent formed a red-colored Ni(II)-PAN complex in Tween 80 media with satisfactory solubility and stability. Conditions such as pH, PAN concentration, type and concentration of micellizing agent were optimized. Molar absorptivity of Ni-PAN complex was found 4.62 x 10{sup 4} L cm{sup -1} mol{sup -1} at 569 nm, under the optimum condition. Calibration graphs were derived by zero, first and second derivative spectrophotometry at maximum wavelengths of 569, 578 and 571 nm with linear ranges of 30-1800, 20-2500 and 30-2000 ng mL{sup -1}, respectively. Precision as standard deviation as well as accuracy as recovery percent were in the range of 1-20 ng mL{sup -1} and 93.3-103.3%, respectively, for the entire of the linear ranges. Spectrophotometric detection limit was 3 ng mL{sup -1} and effects of diverse ions on the first derivative determination of nickel were studied to investigate selectivity of the method. Interferences of cobalt and copper on the nickel determination were prevented using o-phenanthroline as masking agent. The recommended procedures were applied to the various synthetic and stainless steel alloys, tea leaves and human hair, with satisfactory results.

  15. Assessment of the Halogen Content of Brazilian Inhalable Particulate Matter (PM10) Using High Resolution Molecular Absorption Spectrometry and Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry, with Direct Solid Sample Analysis.

    Science.gov (United States)

    de Gois, Jefferson S; Almeida, Tarcisio S; Alves, Jeferson C; Araujo, Rennan G O; Borges, Daniel L G

    2016-03-15

    Halogens in the atmosphere play an important role in climate change and also represent a potential health hazard. However, quantification of halogens is not a trivial task, and methods that require minimum sample preparation are interesting alternatives. Hence, the aim of this work was to evaluate the feasibility of direct solid sample analysis using high-resolution continuum source molecular absorption spectrometry (HR-CS MAS) for F determination and electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICP-MS) for simultaneous Cl, Br, and I determination in airborne inhalable particulate matter (PM10) collected in the metropolitan area of Aracaju, Sergipe, Brazil. Analysis using HR-CS MAS was accomplished by monitoring the CaF molecule, which was generated at high temperatures in the graphite furnace after the addition of Ca. Analysis using ETV-ICP-MS was carried out using Ca as chemical modifier/aerosol carrier in order to avoid losses of Cl, Br, and I during the pyrolysis step, with concomitant use of Pd as a permanent modifier. The direct analysis approach resulted in LODs that were proven adequate for halogen determination in PM10, using either standard addition calibration or calibration against a certified reference material. The method allowed the quantification of the halogens in 14 PM10 samples collected in a northeastern coastal city in Brazil. The results demonstrated variations of halogen content according to meteorological conditions, particularly related to rainfall, humidity, and sunlight irradiation.

  16. A comparison of laser ablation-inductively coupled plasma-mass spectrometry and high-resolution continuum source graphite furnace molecular absorption spectrometry for the direct determination of bromine in polymers

    Science.gov (United States)

    de Gois, Jefferson S.; Van Malderen, Stijn J. M.; Cadorim, Heloisa R.; Welz, Bernhard; Vanhaecke, Frank

    2017-06-01

    This work describes the development and comparison of two methods for the direct determination of Br in polymer samples via solid sampling, one using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and the other using high-resolution continuum source graphite furnace molecular absorption spectrometry with direct solid sample analysis (HR-CS SS-GF MAS). The methods were optimized and their accuracy was evaluated by comparing the results obtained for 6 polymeric certified reference materials (CRMs) with the corresponding certified values. For Br determination with LA-ICP-MS, the 79Br+ signal could be monitored interference-free. For Br determination via HR-CS SS-GF MAS, the CaBr molecule was monitored at 625.315 nm with integration of the central pixel ± 1. Bromine quantification by LA-ICP-MS was performed via external calibration against a single CRM while using the 12C+ signal as an internal standard. With HR-CS SS-GF MAS, Br quantification could be accomplished using external calibration against aqueous standard solutions. Except for one LA-ICP-MS result, the concentrations obtained with both techniques were in agreement with the certified values within the experimental uncertainty as evidenced using a t-test (95% confidence level). The limit of quantification was determined to be 100 μg g- 1 Br for LA-ICP-MS and 10 μg g- 1 Br for HR-CS SS-GF MAS.

  17. Organic sensitizers from D-π-A to D-A-π-A: effect of the internal electron-withdrawing units on molecular absorption, energy levels and photovoltaic performances.

    Science.gov (United States)

    Wu, Yongzhen; Zhu, Weihong

    2013-03-07

    The high performance and low cost of dye-sensitized solar cells (DSSCs) have drawn great interest from both academic and industrial circles. The research on exploring novel efficient sensitizers, especially on inexpensive metal-free pure organic dyes, has never been suspended. The donor-π bridge-acceptor (D-π-A) configuration is mainstream in the design of organic sensitizers due to its convenient modulation of the intramolecular charge-transfer nature. Recently, it has been found that incorporation of additional electron-withdrawing units (such as benzothiadiazole, benzotriazole, quinoxaline, phthalimide, diketopyrrolopyrrole, thienopyrazine, thiazole, triazine, cyanovinyl, cyano- and fluoro-substituted phenyl) into the π bridge as internal acceptors, termed the D-A-π-A configuration, displays several advantages such as tuning of the molecular energy levels, red-shift of the charge-transfer absorption band, and distinct improvement of photovoltaic performance and stability. We apply the D-A-π-A concept broadly to the organic sensitizers containing additional electron-withdrawing units between electron donors and acceptors. This review is projected to summarize the category of pure organic sensitizers on the basis of the D-A-π-A feature. By comparing the structure-property relationship of typical photovoltaic D-A-π-A dyes, the important guidelines in the design of such materials are highlighted.

  18. PAN-6S分光光度法测定钢铁中的铜%Spectrophotometry Determination of Copper in Steel by PAN-6S

    Institute of Scientific and Technical Information of China (English)

    葛传君

    2012-01-01

    Copper content in steel is determined by spectrophotometry using chromogenic reaction of PAN-6S and copper. 1:1 red complex is produced by reaction of PAN-6S and Cu2+ at pH=6-8, and the maximum absorption peak is at 545 rim. The copper content conform to Bill law in 0 - 30μg/25 mL and molar absorptivity is 3.12×104. Copper content can be determined directly after adding masking agent. The method can simplify operation process avoids organic solvent can reduces pollution.%采用分光光度法,利用PAN-6S与铜的显色反应,测定钢铁中的铜含量.在pH值为6-8内,PAN-6s与Cu2+生成1:1的红色配位化合物,最大吸收峰在545nm处,铜含量在0-30Mg/25mL时符合比尔定律,摩尔吸光系数为3.12×104.加入掩蔽剂后,可直接测定钢铁中铜的含量,能够简化操作过程,避免使用有机溶剂.减轻污染.

  19. Absorption and Scattering by Molecules and Particles

    Science.gov (United States)

    Lenoble, Jacqueline; Mishchenko, Michael I.; Herman, Maurice

    2013-01-01

    The Earth's atmosphere absorbs, scatters, and emits electromagnetic radiation. Although air molecules are the primary actors in these processes, aerosol particles are also present ubiquitously and modify the radiation field. In fact, this modification constitutes the very physical basis of aerosol remote sensing. Whenever clouds are present, they have a much larger influence on radiation which largely overshadows the aerosol impact. Therefore, in aerosol remote sensing, one often has to limit observations to cloudless conditions and screen cloudy pixels. In the solar part of the spectrum, molecular absorption is mostly limited to ultraviolet (UV; ozone) and near-infrared (near-IR; carbon dioxide, water vapor) wavelengths and is characterized by strong and narrow oxygen bands. A brief description of atmospheric molecular absorption is presented in Section 2.2. Shortwave aerosol remote sensing is usually performed outside the absorption bands, but some instruments also have channels capturing absorption bands with the objective of quantifying gaseous components.

  20. D-xylose absorption

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003606.htm D-xylose absorption To use the sharing features on this page, please enable JavaScript. D-xylose absorption is a laboratory test to determine ...

  1. Theory of absorption-induced transparency

    Science.gov (United States)

    Rodrigo, Sergio G.; Martín-Moreno, L.

    2014-09-01

    Absorption induced transparency consists in a transmission peak observed in holey metal films when a molecular dye is deposited on top of it [Hutchison et al., Angew. Chem. Int. Ed. 50, 2085 (2011)]. This transmission feature appears unexpectedly close to one of the absorption energies of the molecules, hence its name. Tentative explanations pointed to strong-coupling interactions between plasmons and molecules. However, we recently demonstrated the actual mechanism behind, which takes place through a strong modification of the propagation constant of holes. We also found that absorption induced transparency occurs in single holes and it is not restricted to the optical range.

  2. Oxygen Absorption in Cooling Flows.

    Science.gov (United States)

    Buote

    2000-04-01

    The inhomogeneous cooling flow scenario predicts the existence of large quantities of gas in massive elliptical galaxies, groups, and clusters that have cooled and dropped out of the flow. Using spatially resolved, deprojected X-ray spectra from the ROSAT PSPC, we have detected strong absorption over energies approximately 0.4-0.8 keV intrinsic to the central approximately 1&arcmin; of the galaxy NGC 1399, the group NGC 5044, and the cluster A1795. These systems have among the largest nearby cooling flows in their respective classes and low Galactic columns. Since no excess absorption is indicated for energies below approximately 0.4 keV, the most reasonable model for the absorber is warm, collisionally ionized gas with T=105-106 K in which ionized states of oxygen provide most of the absorption. Attributing the absorption only to ionized gas reconciles the large columns of cold H and He inferred from Einstein and ASCA with the lack of such columns inferred from ROSAT and also is consistent with the negligible atomic and molecular H inferred from H i and CO observations of cooling flows. The prediction of warm ionized gas as the product of mass dropout in these and other cooling flows can be verified by Chandra and X-Ray Multimirror Mission.

  3. The atomic structural dynamics of γ-Al2O3 supported Ir-Pt nanocluster catalysts prepared from a bimetallic molecular precursor: a study using aberration-corrected electron microscopy and X-ray absorption spectroscopy.

    Science.gov (United States)

    Small, Matthew W; Sanchez, Sergio I; Menard, Laurent D; Kang, Joo H; Frenkel, Anatoly I; Nuzzo, Ralph G

    2011-03-16

    This study describes a prototypical, bimetallic heterogeneous catalyst: compositionally well-defined Ir-Pt nanoclusters with sizes in the range of 1-2 nm supported on γ-Al(2)O(3). Deposition of the molecular bimetallic cluster [Ir(3)Pt(3)(μ-CO)(3)(CO)(3)(η-C(5)Me(5))(3)] on γ-Al(2)O(3), and its subsequent reduction with hydrogen, provides highly dispersed supported bimetallic Ir-Pt nanoparticles. Using spherical aberration-corrected scanning transmission electron microscopy (C(s)-STEM) and theoretical modeling of synchrotron-based X-ray absorption spectroscopy (XAS) measurements, our studies provide unambiguous structural assignments for this model catalytic system. The atomic resolution C(s)-STEM images reveal strong and specific lattice-directed strains in the clusters that follow local bonding configurations of the γ-Al(2)O(3) support. Combined nanobeam diffraction (NBD) and high-resolution transmission electron microscopy (HRTEM) data suggest the polycrystalline γ-Al(2)O(3) support material predominantly exposes (001) and (011) surface planes (ones commensurate with the zone axis orientations frequently exhibited by the bimetallic clusters). The data reveal that the supported bimetallic clusters exhibit complex patterns of structural dynamics, ones evidencing perturbations of an underlying oblate/hemispherical cuboctahedral cluster-core geometry with cores that are enriched in Ir (a result consistent with models based on surface energetics, which favor an ambient cluster termination by Pt) due to the dynamical responses of the M-M bonding to the specifics of the adsorbate and metal-support interactions. Taken together, the data demonstrate that strong temperature-dependent charge-transfer effects occur that are likely mediated variably by the cluster-support, cluster-adsorbate, and intermetallic bonding interactions.

  4. Docking mode of delvardine and its analogues into the p66 domain of HIV-1 reverse transcriptase: screening using molecular mechanics-generalized born/surface area and absorption, distribution, metabolism and excretion properties

    Indian Academy of Sciences (India)

    Dipankar Sengupta; Deeptak Verma; Pradeep K Naik

    2007-12-01

    Delvardine and its structural derivatives are important non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTIs). In this work, 15 delvardine analogues were studied. A free energy-of-binding (FEB) expression was developed in the form of an optimized linear combination of van der Waal (vdW), electrostatic, solvation and solvent-accessible surface area (SASA) energy terms. The solvation energy terms estimated by generalized born/surface area (GB/SA) play an important role in predicting the binding affinity of delvardine analogues. Out of 15 derivatives, substitution of CH3 with H at the Y and R positions, as well as substitution of SO2CH3 with only CH2 at the Z position in S2, S8 and S12 analogues, were found to be the most potent (glide score = –7.60, –8.06 and –7.44; pIC50 = 7.28, 7.37 and 7.64) in comparison with the template delvardine (which is used currently as the drug candidate). All the three analogues also passed the absorption, distribution, metabolism and excretion (ADME) screening and Lipinski’s rule of 5, and have the potential to be used for second-generation drug development. The work demonstrates that dock molecular mechanics-generalized born/surface area (MM–GB/SA–ADME) is a promising approach to predict the binding activity of ligands to the receptor and further screen for a successful candidate drug in a computer-aided rational drug design.

  5. Fluorine speciation analysis using reverse phase liquid chromatography coupled off-line to continuum source molecular absorption spectrometry (CS-MAS): identification and quantification of novel fluorinated organic compounds in environmental and biological samples.

    Science.gov (United States)

    Qin, Zhiwei; McNee, David; Gleisner, Heike; Raab, Andrea; Kyeremeh, Kwaku; Jaspars, Marcel; Krupp, Eva; Deng, Hai; Feldmann, Jörg

    2012-07-17

    Driven by increasing demand for the monitoring of industrial perfluorinated compounds (PFCs), the identification of novel fluorine containing compounds (FOCs) and the tracking of organofluorine drugs and their degradation products, there is a clear need for sensitive, fluorine-specific detection of unknown FOCs. Here we report the first ever direct fluorine-specific (speciation) method; capable of individually detecting untargeted FOCs in environmental and biological samples through the application of continuum source molecular absorption spectrometry (CS-MAS) using a commercial CS-AAS. Two model FOCs (2,4,6, trifluorobenzoic acid (TFBA) and 5-fluoroindol-5-carboxylic acid (FICA)) were used, achieving fluorine-specific detection across a range of 0.1 to 300 ng/mL fluorine, corresponding to a limit of detection of 4 pg F and 5.26 nM for both compounds. Both TFBA and FICA showed a similar response to CS-MAS detection, potentially enabling the quantification of fluorine content in novel FOCs without having molecular standards available. This paper also reports the use of reverse-phase high performance liquid chromatography (RP-HPLC) coupled off-line with CS-MAS for the identification of single organofluorines in a mixture of FOCs via fraction collection. The linear range of both FOCs was determined to be from 1 to 500 ng/mL. The limits of detection of those species were just above 1 ng/mL (100 pg) and can therefore compete with targeted analytical methods such as ESI-MS. Finally, as a proof of principle the analysis of a fluoride-containing groundwater sample from Ghana demonstrated that this method can be used in the detection of novel FOCs, with identification achieved through parallel ESI-MS. Coupled HPLC-CS-MAS/ESI-MS is the first analytical methodology capable of selectively detecting and identifying novel FOCs, making possible the quantification of all fluorine containing compounds in one sample. This is the necessary analytical requirement to perform

  6. Coordination nature of aluminum (oxy)hydroxides formed under the influence of low molecular weight organic acids and a soil humic acid studied by X-ray absorption spectroscopy

    Science.gov (United States)

    Xu, R. K.; Hu, Y. F.; Dynes, J. J.; Zhao, A. Z.; Blyth, R. I. R.; Kozak, L. M.; Huang, P. M.

    2010-11-01

    Organic ligands in the environment hinder the formation of crystalline Al precipitation products by perturbing the hydrolytic and polymeric reactions of Al resulting in the formation of short-range ordered (SRO) mineral colloids with varying degrees of crystallinity. However, the effect of these ligands on the mechanisms of their formation and nature of the transformation products of Al (oxy)hydroxides at the atomic and molecular levels is not well understood. In this study, the coordination structure of Al in Al (oxy)hydroxides formed under the influence of varying concentrations of low molecular weight (LMW) organic acids such as citric, malic, salicylic and acetic acids and a humic acid (HA) was investigated with X-ray absorption near edge structure (XANES) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis. The Al K- and L-edge XANES spectra showed that with increasing LMW organic acid concentration the coordination number of Al changed from 6-fold to a mixture of 4- and 6-fold, except for acetate as acetate was unable to perturb the formation of Al (oxy)hydroxides at the acetate/Al molar ratio (MR) = 0.1. The proportion of 4-fold to 6-fold coordinated Al in the Al precipitation products depended on the structure and functionality of the LMW organic acids. The incorporation of the LMW organic acid into the network structure of Al (oxy)hydroxides prevented the formation of sheets/inter-layer H-bonding that was required for the formation of crystalline Al (oxy)hydroxides. The HA used in this study only slightly perturbed the crystallization of the Al (oxy)hydroxides at the concentrations used. The Al K-edge data showed that Al coordination number had not been altered in the presence of HA. The findings obtained in the present study are of fundamental significance in understanding the physicochemical behavior of soils and sediments, and their relation to the accumulation and transport of nutrients and pollutants in the

  7. Determination of mancozeb in marigold( Tagetes erecta L.) by molecular absorption spectrometry%分子吸收光度法测定万寿菊中代森锰锌残留量

    Institute of Scientific and Technical Information of China (English)

    刘宏程; 何瑾; 黄兴富; 邵金良; 郑兵; 黎其万

    2012-01-01

    目的:采用分子吸收光度法测定万寿菊中代森锰锌残留.方法:通过蒸馏和溶液吸收实验装置,氯化亚锡催化,二乙基二硫代氨基甲酸钠分解定量产生二硫化碳气体,通过浓硫酸脱氧脱水,氢氧化钾的甲醇液吸收,用分光光度法在304 nm波长处测定其标准曲线.代森锰锌以平均相对分子质量333计,可通过平均相对分子质量计算出代谢锰锌的含量.结果:万寿菊中添加浓度为10 mg·kg-1和20mg· kg-1(以二硫化碳计)的回收率(n=5)分别为95.9%和93.2%,RSD分别为4.8%和3.7%;最低检测限为2 mg·kg-.结论:该方法操作简单,灵敏度高,适合大批量样品的检测.%Objective: To establish a convenient and fast method for determination of mancozeb residue level in marigold ( Tagetes erecta L. ). Methods: The method included distillation and absorption parts. Sodium diethyldi-thiocarbamate in SnCl2 catalyst was decomposed and released gas carbon disulfur quantitatively, passed through sulphuric acid solution,was absorbed by KOH/CH3OH solutions,then standard curve was determined by spectrometry with 304 nm wavelength. The meaning relative molecular mass of mancozeb was 333, so mancozeb content was calculated by the meaning relative molecular mass. Results: The recoveries ( n = 5 ) of mancozeb in marigold were 95. 9% ,93. 2% at added concentrations of 10 and 20 mg · kg-1 (carbon disulfide) ,with their RSDs of 4. 8% and 3. 7% .respectively. The detection limits were 2 mg · kg-1. Conclusion; The method is more selective and sensitive and suited for large samples analysis.

  8. Laser isotope separation by multiple photon absorption

    Science.gov (United States)

    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.

  9. The HI absorption "Zoo"

    Science.gov (United States)

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

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1) detections, which are associated with gas-rich mergers, we find three new cases of profiles with blueshifted broad wings (with FW20 ≳ 500 km s-1) in high radio power AGN. These detections are good candidates for being HI outflows. Together with the known cases of outflows already included in the sample (3C 293 and

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

    Science.gov (United States)

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

    2013-06-01

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

  11. 8- to 13-micron spectrophotometry of Comet IRAS-Araki-Alcock

    Science.gov (United States)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 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.

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

    Science.gov (United States)

    Warren, W. H., Jr.

    1982-01-01

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

  15. Determination of total flavonoids in three Sedum crude drugs by UV-Vis spectrophotometry

    Directory of Open Access Journals (Sweden)

    Yujie Chen

    2010-01-01

    Full Text Available A simple, rapid UV-Vis spectrophotometry method for the determination of total flavonoids in Sedum sarmentosum Bunge., S. lineare Thunb., and S. erythrostictum Migo. was developed, with a good linearity, precision, and stability. The detection wavelength was set at 500 nm, and an extraction solvent was optimized. Through the comparative study of multiple samples of the three plant drugs, their collected seasons and the habitats can be preliminarily ascertained, which may help to control the quality of the medicines to some extent.

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

    Science.gov (United States)

    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.

  17. A novel cyanide-selective colorimetric and fluorescent chemosensor: first molecular security keypad lock based on phosphotungstic acid and CN- inputs.

    Science.gov (United States)

    Tavallali, Hossein; Deilamy-Rad, Gohar; Parhami, Abolfath; Hasanli, Nahid

    2014-02-15

    Rhodamine B (RhB) an available dye has been developed as novel and efficient colorimetric and fluorometric chemosensor for cyanide ions in an absolutely aqueous media. The UV-vis absorption and fluorescent emission titrations experiments have been employed to study the sensing process. RhB could act as an efficient "ON-OFF" fluorescent response for phosphotungstic acid (H3PW12O40 or PTA) based on an ion associate process. Also (RhB(+))3 · PTA(3-) could operate as an "OFF-ON" fluorescent sensor for cyanide anions based on a ligand substitution process. It has been identified as highly sensitive probe for CN(-) which responds at 0.3 and 0.04 μmol L(-1) concentration levels by absorption and fluorescent method respectively. Depending upon the sequence of addition of PTA and CN(-) ions into the solution, RhB could be as a molecular security keypad lock with PTA and CN(-) inputs. The ionic inputs to new fluorophore have been mimicked as a superimposed electronic molecular keypad lock. The results were compared successfully (>96%) with the data of a spectrophotometry approved method (EPA 9014-1) for cyanide ions. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. 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.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-01-19

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

  20. Simultaneous determination of anthocyanoside and beta-carotene by third-derivative ultraviolet spectrophotometry

    Directory of Open Access Journals (Sweden)

    "Effat Souri

    2005-01-01

    Full Text Available Derivative spectrophotometry offers a useful approach for the analysis of drugs in multi-component mixtures. In this study a third-derivative spectrophotometry method was used for simultaneous determination of anthocyanoside and beta-carotene using the zero-crossing technique. The measurements were carried out at wavelengths of 625 and 540 nm for anthocyanoside and beta-carotene respectively. The method was found to be linear (r2>0.999 in the range of 125-750 µg/mL for anthocyanoside in the presence of 25 µg/mL beta-carotene at 625 nm. The same linear correlation was also obtained (r2>0.997 in the range of 6.25-37.50 µg/mL for beta-carotene in the presence of 500 µg/mL of anthocyanoside at 540 nm. The limit of determination was 125 and 6.25 µg/mL for anthocyanoside and beta-carotene respectively. The method was successfully applied for simultaneous determination of anthocyanoside and beta-carotene in pharmaceutical preparations without any interferences from excipients.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

    Science.gov (United States)

    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 Spectrophotometry has a higher correlation with clinical outcome and a better predictive value than other nonmeasurable, nonquantitative, dependent variables.

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

    Science.gov (United States)

    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.

  5. Feature selection versus feature compression in the building of calibration models from FTIR-spectrophotometry datasets.

    Science.gov (United States)

    Vergara, Alexander; Llobet, Eduard

    2012-01-15

    Undoubtedly, FTIR-spectrophotometry has become a standard in chemical industry for monitoring, on-the-fly, the different concentrations of reagents and by-products. However, representing chemical samples by FTIR spectra, which spectra are characterized by hundreds if not thousands of variables, conveys their own set of particular challenges because they necessitate to be analyzed in a high-dimensional feature space, where many of these features are likely to be highly correlated and many others surely affected by noise. Therefore, identifying a subset of features that preserves the classifier/regressor performance seems imperative prior any attempt to build an appropriate pattern recognition method. In this context, we investigate the benefit of utilizing two different dimensionality reduction methods, namely the minimum Redundancy-Maximum Relevance (mRMR) feature selection scheme and a new self-organized map (SOM) based feature compression, coupled to regression methods to quantitatively analyze two-component liquid samples utilizing FTIR spectrophotometry. Since these methods give us the possibility of selecting a small subset of relevant features from FTIR spectra preserving the statistical characteristics of the target variable being analyzed, we claim that expressing the FTIR spectra by these dimensionality-reduced set of features may be beneficial. We demonstrate the utility of these novel feature selection schemes in quantifying the distinct analytes within their binary mixtures utilizing a FTIR-spectrophotometer.

  6. THE STUDY OF INTERACTION OF SOLID—LIQUID ADSORPTION SYSTEM BY USING THE FLOW INJECTION—SPECTROPHOTOMETRY SYSTEM

    Institute of Scientific and Technical Information of China (English)

    HEGuangping; CHENBingren; 等

    2001-01-01

    The flow injection analysis was firatly used for studying a solid-liquid adsorption system,and the dynamics process in the adsorption of adyestuff with regenerable chitin was traced by an online method of flow injection-spectrophotometry,Experimental results indicate that there is a linearization between the tested signals and the height of peaks with reciprocity coefficient 0.9999 by using the flow injection-spectrophotometry system to study the dynamics adsorption process in solid-liquid system.The method shows a good stability and reproducibility.It provides a new method for the studies on adsorption dynamics in solid-liquid system.

  7. THE STUDY OF INTERACTION OF SOLID-LIQUID ADSORPTION SYSTEM BY USING THE FLOW INJECTION-SPECTROPHOTOMETRY SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The flow injection analysis was firstly used for studying a solid-liquid adsorption system,and the dynamics process in the adsorption of dyestuff with regenerable chitin was traced by an online method of flow injection-spectrophotometry. Experimental results indicate that there is a linearization between the tested signals and the height of peaks with reciprocity coefficient 0.9999by using the flow injection-spectrophotometry system to study the dynamics adsorption process in solid-liquid system. The method shows a good stability and reproducibility. It provides a new method for the studies on adsorption dynamics in solid- liquid system.

  8. Determination of ranitidine hydrochloride in pharmaceutical preparations by titrimetry and visible spectrophotometry using bromate and acid dyes.

    Science.gov (United States)

    Basavaiah, K; Nagegowda, P

    2004-02-01

    Four new methods using titrimetry and spectrophotometry are described for the determination of ranitidine hydrochloride (RNH) with potassium bromate as the oxidimetric reagent and acid dyes, methyl orange, indigo carmine and metanil yellow. In direct titrimetry (method A), the drug is titrated directly with bromate in acid medium and in the presence of excess of bromide using methyl orange indicator. In back titrimetry (method B), the drug is treated with a measured excess of bromate in the presence of bromide and acid, and the unreacted bromine is determined iodometrically. Both spectrophotometric methods are based on the oxidation of RNH by a known excess of bromate in acid medium and in the presence of excess of bromide followed by estimation of surplus oxidant by reacting with either indigo carmine (method C) or metanil yellow (method D), and measuring the absorbance at 610 or 530 nm. In methods B, C and D, reacted oxidant corresponds to the drug content. The experimental conditions are optimized. Titrimetric procedures are applicable over the ranges 1-10 mg (A) and 1-17 mg (B), and the reaction stoichiometry is found to be 1:1 (BrO(-)(3): RNH). In spectrophotometric methods, the absorbance is found to increase linearly with increasing concentration of RNH, which is corroborated by the calculated correlation coefficient (r) of 0.9984 (C) and 0.9976 (D). The systems obey Beer's law for 2-12 and 1-7 microg ml(-1), for methods C and D, respectively. Method D with a molar absorptivity of 9.82 x 10(4) l mol(-l) cm(-1) is found to be more sensitive than method C ( epsilon = 2.06 x l0(4) l mol(-1) cm(-1)). The limits of detection and quantification are reported for both the spectrophotometric methods. The proposed methods were applied successfully to the determination of RNH in tablets and injections. The reliability of the assay was established by parallel determination by the official method and by recovery studies.

  9. Absorption of Soluble Gases by Atmospheric Nanoaerosols

    CERN Document Server

    Elperin, Tov; Krasovitov, Boris; Lushnikov, Alexey

    2012-01-01

    We investigate mass transfer during absorption of atmospheric trace soluble gases by a single droplet whose size is comparable to the molecular mean free path in air at normal conditions. It is assumed that the trace reactant diffuses to the droplet surface and then reacts with the substances inside the droplet according to the first order rate law. Our analysis applies a flux-matching theory of transport processes in gases and assumes constant thermophysical properties of the gases and liquids. We derive an integral equation of Volterra type for the transient molecular flux density to a liquid droplet and solve it numerically. Numerical calculations are performed for absorption of sulfur dioxide (SO2), dinitrogen trioxide (N2O3) and chlorine (Cl2) by liquid nanoaerosols accompanied by chemical dissociation reaction. It is shown that during gas absorption by nanoaerosols the kinetic effects play significant role, and neglecting kinetic effects leads to significant overestimation of the soluble gas flux into a...

  10. Enhanced Gas Absorption in the Ionic Liquid 1-n-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide ([hmim][Tf{sub 2}N]) Confined in Silica Slit Pores: A Molecular Simulation Study

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Wei; Luebke, David R

    2013-05-07

    Two-dimensional NP{sub xy}T and isostress-osmotic (N{sub 2}P{sub xy}Tf{sub 1}) Monte Carlo simulations were used to compute the density and gas absorption properties of the ionic liquid (IL) 1-n-hexyl-3- methylimidazolium bis(Trifluoromethylsulfonyl)amide ([hmim][Tf{sub 2}N]) confined in silica slit pores (25-45 Å). Self-diffusivity values for both gas and IL were calculated from NVE molecular dynamics simulations using both smooth and atomistic potential models for the silica. Simulations show that the molar volume for [hmim][Tf{sub 2}N] confined in 25-45 Å silica slit pores are 12-31% larger than for the bulk IL at 313-573 K and 1 bar. The amounts of CO{sub 2}, H{sub 2}, and N{sub 2} absorbed in the confined IL are typically 1.1-3 times larger than in the bulk IL due to larger molar volumes for the confined IL compared to the bulk IL. The CO{sub 2}, N{sub 2}, and H{sub 2} molecules are generally absorbed close to the silica wall where the IL density is very low. This arrangement causes the self-diffusivities for these gases in the confined IL to be 2 to 8 times larger than in the bulk IL at 298-573 K. The solubility for water in the confined and bulk ILs are similar, which is likely due to strong water interactions with [hmim][Tf{sub 2}N] through hydrogen-bonding resulting in the confined IL molar volume playing a less important role in determining H{sub 2}O solubility. Water molecules were largely absorbed in the IL-rich region rather than close to the silica wall. The self-diffusivities for water correlate with the confined IL. The confined IL exhibits self-diffusivities larger than the bulk IL at lower temperatures, but smaller than the bulk IL at higher temperatures. The findings from simulations are consistent with available experimental data for similar confined IL systems.

  11. Enhanced Gas Absorption in the Ionic Liquid 1- n -Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide ([hmim][Tf 2 N]) Confined in Silica Slit Pores: A Molecular Simulation Study

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Wei; Luebke, David R.

    2013-05-07

    Two-dimensional NP{sub xy}T and isostress-osmotic (N{sub 2}P{sub xy}Tf{sub 1}) Monte Carlo simulations were used to compute the density and gas absorption properties of the ionic liquid (IL) 1-n-hexyl-3- methylimidazolium bis(Trifluoromethylsulfonyl)amide ([hmim][Tf{sub 2}N]) confined in silica slit pores (25-45 Å). Self-diffusivity values for both gas and IL were calculated from NVE molecular dynamics simulations using both smooth and atomistic potential models for the silica. Simulations show that the molar volume for [hmim][Tf{sub 2}N] confined in 25-45 Å silica slit pores are 12-31% larger than for the bulk IL at 313-573 K and 1 bar. The amounts of CO{sub 2}, H{sub 2}, and N{sub 2} absorbed in the confined IL are typically 1.1-3 times larger than in the bulk IL due to larger molar volumes for the confined IL compared to the bulk IL. The CO{sub 2}, N{sub 2}, and H{sub 2} molecules are generally absorbed close to the silica wall where the IL density is very low. This arrangement causes the self-diffusivities for these gases in the confined IL to be 2 to 8 times larger than in the bulk IL at 298-573 K. The solubility for water in the confined and bulk ILs are similar, which is likely due to strong water interactions with [hmim][Tf{sub 2}N] through hydrogen-bonding resulting in the confined IL molar volume playing a less important role in determining H{sub 2}O solubility. Water molecules were largely absorbed in the IL-rich region rather than close to the silica wall. The self-diffusivities for water correlate with the confined IL. The confined IL exhibits self-diffusivities larger than the bulk IL at lower temperatures, but smaller than the bulk IL at higher temperatures. The findings from simulations are consistent with available experimental data for similar confined IL systems.

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

    Science.gov (United States)

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

    2005-11-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  15. Spectrophotometry of asteroids 32 Pomona, 145 Adeona, 704 Interamnia, 779 Nina, 330825, and 2012 QG42 and laboratory study of possible analog samples

    CERN Document Server

    Busarev, Vladimir V; Rusakov, Vyacheslav S; Puzin, Vasiliy B; Kravtsov, Valery V

    2015-01-01

    Six asteroids including two NEAs, one of which is PHA, accessible for observation in September 2012 were investigated using a low-resolution spectrophotometry in the range 0.35-0.90 um with the aim to study features of their reflectance spectra. For the first time we discovered likely spectral signs (as a maximum at 0.4-0.6 um in reflectance spectra) of simultaneous sublimation activity and presence of a temporal coma on three primitive-type main-belt asteroids, Adeona, Interamnia, and Nina, being at perihelion distances or approaching to it. We suggest that such a cometary-like activity may be a common phenomenon at the highest subsolar surface temperatures for C and close type asteroids including considerable amounts of H2O and CO2 ices beneath the surface. However, excavation of fresh ice at recent impact event(s) could be an alternative explanation of the phenomenon. Similar absorption bands centered at 0.38, 0.44 and 0.67-0.71 um registered in the reflectance spectra of Adeona, Interamnia, and Nina clear...

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

    Science.gov (United States)

    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).

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

    Science.gov (United States)

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

    2015-01-02

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

  18. Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization

    Science.gov (United States)

    Zhu, Yue; Chen, Chia-Hsiu; Wilson, Zechariah; Savukov, Igor; Hilty, Christian

    2016-09-01

    Hyperpolarization methods offer a unique means of improving low signal strength obtained in low-field NMR. Here, simultaneous measurements of NMR at a field of 0.7 mT and laser optical absorption from samples hyperpolarized by dissolution dynamic nuclear polarization (D-DNP) are reported. The NMR measurement field closely corresponds to a typical field encountered during sample injection in a D-DNP experiment. The optical spectroscopy allows determination of the concentration of the free radical required for DNP. Correlation of radical concentration to NMR measurement of spin polarization and spin-lattice relaxation time allows determination of relaxivity and can be used for optimization of the D-DNP process. Further, the observation of the nuclear Overhauser effect originating from hyperpolarized spins is demonstrated. Signals from 1H and 19F in a mixture of trifluoroethanol and water are detected in a single spectrum, while different atoms of the same type are distinguished by J-coupling patterns. The resulting signal changes of individual peaks are indicative of molecular contact, suggesting a new application area of hyperpolarized low-field NMR for the determination of intermolecular interactions.

  19. The O2-Evolving Complex of Photosystem II: Recent Insights from Quantum Mechanics/Molecular Mechanics (QM/MM), Extended X-ray Absorption Fine Structure (EXAFS), and Femtosecond X-ray Crystallography Data.

    Science.gov (United States)

    Askerka, Mikhail; Brudvig, Gary W; Batista, Victor S

    2017-01-17

    Efficient photoelectrochemical water oxidation may open a way to produce energy from renewable solar power. In biology, generation of fuel due to water oxidation happens efficiently on an immense scale during the light reactions of photosynthesis. To oxidize water, photosynthetic organisms have evolved a highly conserved protein complex, Photosystem II. Within that complex, water oxidation happens at the CaMn4O5 inorganic catalytic cluster, the so-called oxygen-evolving complex (OEC), which cycles through storage "S" states as it accumulates oxidizing equivalents and produces molecular oxygen. In recent years, there has been significant progress in understanding the OEC as it evolves through the catalytic cycle. Studies have combined conventional and femtosecond X-ray crystallography with extended X-ray absorption fine structure (EXAFS) and quantum mechanics/molecular mechanics (QM/MM) methods and have addressed changes in protonation states of μ-oxo bridges and the coordination of substrate water through the analysis of ammonia binding as a chemical analog of water. These advances are thought to be critical to understanding the catalytic cycle since protonation states regulate the relative stability of different redox states and the geometry of the OEC. Therefore, establishing the mechanism for substrate water binding and the nature of protonation/redox state transitions in the OEC is essential for understanding the catalytic cycle of O2 evolution. The structure of the dark-stable S1 state has been a target for X-ray crystallography for the past 15 years. However, traditional X-ray crystallography has been hampered by radiation-induced reduction of the OEC. Very recently, a revolutionary X-ray free electron laser (XFEL) technique was applied to PSII to reveal atomic positions at 1.95 Å without radiation damage, which brought us closer than ever to establishing the ultimate structure of the OEC in the S1 state. However, the atom positions in this crystal

  20. The HI absorption "Zoo"

    NARCIS (Netherlands)

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

    2015-01-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis o

  1. Bioacoustic Absorption Spectroscopy

    Science.gov (United States)

    2016-06-07

    frequencies (Ching and Weston, 1971). RESULTS Measured resonance frequencies of absorption lines, which were attributed to adult (~ 1.3 khz) and juvenile ...of adult and juvenile sardines. These results suggest that bioacoustic absorption spectroscopy measurements permit isolation of juvenile from adult...from broadband tomographic transmission loss measurements over large areas . 2. Depths of sardines and contours of phytoplankton concentrations vs. time

  2. Nutrition and magnesium absorption.

    NARCIS (Netherlands)

    Brink, E.J.

    1992-01-01

    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true magnesium abs

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

    Science.gov (United States)

    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.

  4. Absorption of Flue-Gas Components by Ionic Liquids

    DEFF Research Database (Denmark)

    Kolding, Helene; Thomassen, Peter Langelund; Mossin, Susanne;

    2014-01-01

    for absorption of NOX, CO2 and SO2 are demonstrated and the possible mechanism of absorption described on the molecular level. Special focus regards the interaction of the ILs with water vapor, which is an important feature in envisaged application of flue gas cleaning in power plants, waste incineration plants...

  5. 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

    Energy Technology Data Exchange (ETDEWEB)

    Dadfarnia, Shayessteh, E-mail: sdadfarnia@yazd.ac.ir; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

    2013-12-15

    Graphical abstract: Pass the sample through the basic alumina column ⇒ elute retained uranium along with the cations ⇒ convert the uranium to its anionic benzoate complex ⇒ extract its ion pair with malachite green into small volume of chloroform by DLLME ⇒ measure its absorption at 621 nm using fiber optic-linear array detection spectrophotometry. -- Highlights: • By combination of SPE and DDLME a high preconcentration factor of 2500 was obtained. • Development of SPE-DDLME-Spectrophotometric method for det. of trace amounts of uranium. • Ultra trace amount of uranium in water samples was det. by the proposed method. • The detection limit of the proposed method is comparable to the most sensitive method. • The proposed method is a free interference spectrophotometric method for uranium det. -- Abstract: 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{sup −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{sup −1}, and a relative standard deviation of 4.1% (n = 6) at 400 ng L{sup −1} were obtained. The

  6. 纸层析-分光光度法检测茶氨酸%Determination of Theanine in Tea (Camellia sinensis L.) by Paper Chromatography-Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    马雪泷; 邹鹏飞; 王荡强; 曹顺利; 房江育; 王昶

    2012-01-01

    为了满足普通实验室对茶中茶氨酸测定的需要,研究了茶氨酸的纸层析-分光光度检测方法.结果表明,用茚三酮-乙醇水溶液做展层剂,对茶苗根.芽叶和茶叶的水浸提液进行纸层析,能够有效地将茶氨酸与其它氨基酸分离,紫色色斑清晰而均匀.用乙醇溶液洗脱色斑后用分光光度计在570 nm比色,在20~70 μL茶氨酸溶液点样量范围内其含量与吸光度呈线性关系.本方法检出限为0.0057 mg·mL-1,测定下限为0.0191 mg·mL-1,平均回收率90.28%~115.38%,平均相对标准差1.51%,具有安全、药品种类少和操作步骤简单等特点.%To meet the needs of ordinary laboratory determination of theanine, paper chromatographic-spectrophotometry was developed. The results showed that by paper chromatography, ninhydrin-ethanol water solution could effectively separate theanine from other amino acids extracted in the water from roots or shoots of tea seedling or from tea. The purple stains were clear and even. After the stains were eluted with ethanol solution, theanine content could be assayed with the spectrophotometer at 570 nm. The theanine content appeared a linera relationship with the absorption value when the solution was sported on the paper at the range of 20-70 uL. The detection limit was 0.0057 mg-mL"' and the lowest detection limit was 0.0191 mg-mL'1. The average recovery ranged from 90.28% to 115.38%, and the average relative standard deviation was 1.51%. The paper chromatography-spectrophotometry characterizes safety, fewer chemicals, and easy to operate.

  7. Simultaneous determination of phenol and mononitrophenol isomers using PLS regression and conventional and derivative spectrophotometry.

    Science.gov (United States)

    Shamsipur, Mojtaba; Ghavami, Raoof; Sharghi, Hashem; Hemmateenejad, Bahram

    2005-01-01

    The partial least squares regression method (PLS) was tested as a calibration procedure for the simultaneous determination of phenol, o-nitrophenol, m-nitrophenol and p-nitrophenol by both conventional and first derivative UV/Vis spectrophotometry. The experiments were conducted in the acidic, neutral and basic media. The results obtained by the application of the PLS procedure on the conventional and first derivative spectra in two solvent media were compared. It was found that the results obtained in the basic medium have better performance characteristics than those obtained in the acidic or neutral media. Comparable results were obtained in the case of both conventional and first derivative absorbance data. The proposed method was applied to the determination of the four phenol derivatives in natural spiked water samples at concentration levels between 1.0 and 10.0 microg ml(-1) with average recoveries in the range 96% - 99%.

  8. Measurement of vascular permeability in spinal cord using Evans Blue spectrophotometry and correction for turbidity.

    Science.gov (United States)

    Warnick, R E; Fike, J R; Chan, P H; Anderson, D K; Ross, G Y; Gutin, P H

    1995-05-01

    Vascular permeability can be visualized by Evans Blue (EB) extravasation and quantified by spectrophotometry after formamide extraction of the tissue. However, formamide extracts show significant turbidity, which may contribute to the total optical density at the wavelength of measurement (e.g., 620 lambda). We developed a simple method for estimating the component of the total optical density of a dyed specimen contributed by turbidity. Our method, which uses a determination of turbidity made at another point of the light spectrum (740 lambda), was more precise than two other EB quantification techniques. We therefore recommend it for individual correction of formamide extracts of spinal cord specimens. The application of this technique to the brain remains to be determined.

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

    Science.gov (United States)

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

    2012-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Valerio Pini

    2016-06-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

    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.

  13. Simultaneous Determination of Cobalt (II and Nickel (II By First Order Derivative Spectrophotometry in Micellar Media

    Directory of Open Access Journals (Sweden)

    Rajni Rohilla

    2012-01-01

    Full Text Available A first-derivative spectrophotometry method for the simultaneous determination of Co (II and Ni (II with Alizarin Red S in presence of Triton X-100 is described. Measurements were made at the zero-crossing wavelengths at 549.0 nm for Co (II and 546.0 nm for Ni (II. The linearity is obtained in the range of 0.291- 4.676 μg/ml of Ni (II and 0.293- 4.124 μg/ml of Co (II in the presence of each other by using first derivative spectrophotometric method. The possible interfering effects of various ions were studied. The validity of the method was examined by using synthetic mixtures of Co (II and Ni (II. The developed derivative procedure, using the zero crossing technique, has been successfully applied for the simultaneous analysis of Co (II and Ni (II in spiked water samples.

  14. Kinetics and Mechanism of the Oxidation of Glycol by Dihydroxyditelluratoargentate(Ⅲ) with Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The kinetics of the oxidation of glycol by dihydroxyditelluratoargentate (Ⅲ) complex(DDA) was studied in alkaline medium with spectrophotometry(in a temperature range of 16.6-40 ℃).The first-order rates with respect to glycol and Ag(Ⅲ) were all found.The rates increased with the increase in [OH-] and decreased with the increase in [TeO2-4].No effect was found with the addition of KNO3 and no free radical was detected.In view of this,the dihydroxymonotelluratoargentate(Ⅲ) species(DMA) is assumed to be the active species.A plausible mechanism involving a two-electron transfer is proposed,and the rate equation derived from the mechanism can explain all experimental observations.Activation parameters of the rate-determining step and constants are evaluated.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  17. Determination of Carbohydrazide and Kinetics of Condensation reaction of Carbohydrazide with Malachite Green by Spectrophotometry

    Institute of Scientific and Technical Information of China (English)

    伍涛; 张同来; 陈红艳; 张建国

    2005-01-01

    The kinetics of the condensation reaction of malachite green and carbohydrazide was studied by spectrophotometry in aqueous solution in the temperature range of 15.0-22.0℃. The reaction was found to be second-order overall, first-order with respect to each reactant. The effect of ionic strength on the reaction has negative salt effect in the range of 0.2-1.0 mol·L-1. A mechanism of the reaction between malachite green and carbohydrazide was proposed, and the rate equation derived from the mechanism can explain all experimental observations properly. Based on this reaction, a method of determining the content of carbohydrazide in the concentration range of (0.02-0.5) )<10-3 mol·L-1 was proposed.

  18. DETERMINATION OF POLYDATIN IN POLYGONUM CUSPIDTUM SIEB.ET ZUCC.BY TLC-FLUORESCENCE SPECTROPHOTOMETRY

    Institute of Scientific and Technical Information of China (English)

    许昭; 唐玉海; 李健军; 杨云

    2004-01-01

    Objective A method of TLC-fluorescence spectrophotometry was established to assay the content of polydatin in polygonum cuspidatum sieb. et zucc. Methods: Polydatin was extracted by methanol and separated with chloroform-acetone-formic acid-water (4∶4∶0.5∶0.2) by thin layer chromatography. The excitation wavelength and emission wavelength were 284nm and 384nm, respectively. Results The linear regression equation of the calibration graph was y=7.02179x+4.5143, a linear regression correlative coefficient r=0.9936. Conclusion This method was proved simple, stable and sensitive. It can be used in quality control of herbs.

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

    Science.gov (United States)

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

    2013-06-01

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

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

    Science.gov (United States)

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

    1979-01-01

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

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

    Science.gov (United States)

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

    1982-01-01

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

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

    Science.gov (United States)

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

    1981-01-01

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

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

    Science.gov (United States)

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

    2011-02-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2016-06-21

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

  6. Quasar Absorption Studies

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. Exciton absorption and intramolecular Penning ionisation in small molecular clusters. Pt. 1. (N/sub 2/O)/sub n/ and C/sub 6/H/sub 5/CN. (N/sub 2/O)/sub n/

    Energy Technology Data Exchange (ETDEWEB)

    Kamke, B.; Kamke, W.; Herrmann, R.; Hertel, I.V.

    1989-02-01

    Photoionisation efficiency (PIE)-spectra are measured for small (N/sub 2/O)/sub n/-clusters, n=2 ... 8, using synchrotron radiation from the electron storage ring BESSY at Berlin. Ionisation thresholds are reported. Resonances in the wavelength-range 97 ... 100 nm for n>2 are attributed to exciton absorption with N/sub 2/O-Rydberg levels, series I and II parentage. This interpretation is supported by measurements of the PIE of mixed benzonitrile x (N/sub 2/O)/sub n/ clusters where benzonitrile serves as a monitor for photon absorption in N/sub 2/O at energies above the ionisation limit of benzonitrile.

  9. Molecular Stirrers in Action

    NARCIS (Netherlands)

    Chen, Jiawen; Kistemaker, Jos C. M.; Robertus, Jort; Feringa, Ben L.

    2014-01-01

    A series of first-generation light-driven molecular motors with rigid substituents of varying length was synthesized to act as "molecular stirrers". Their rotary motion was studied by H-1 NMR and UV-vis absorption spectroscopy in a variety of solvents with different polarity and viscosity. Quantitat

  10. Soliton absorption spectroscopy

    CERN Document Server

    Kalashnikov, V L

    2010-01-01

    We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique.

  11. Absorption heat pump system

    Science.gov (United States)

    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.

  12. Zeeman atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hadeishi, T.; McLaughlin, R.

    1978-08-01

    The design and development of a Zeeman atomic absorption spectrometer for trace element analysis are described. An instruction manual is included which details the operation, adjustment, and maintenance. Specifications and circuit diagrams are given. (WHK)

  13. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...... learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning...

  14. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...... learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning...

  15. Record Multiphoton Absorption Cross-Sections by Dendrimer Organometalation.

    Science.gov (United States)

    Simpson, Peter V; Watson, Laurance A; Barlow, Adam; Wang, Genmiao; Cifuentes, Marie P; Humphrey, Mark G

    2016-02-12

    Large increases in molecular two-photon absorption, the onset of measurable molecular three-photon absorption, and record molecular four-photon absorption in organic π-delocalizable frameworks are achieved by incorporation of bis(diphosphine)ruthenium units with alkynyl linkages. The resultant ruthenium alkynyl-containing dendrimers exhibit strong multiphoton absorption activity through the biological and telecommunications windows in the near-infrared region. The ligated ruthenium units significantly enhance solubility and introduce fully reversible redox switchability to the optical properties. Increasing the ruthenium content leads to substantial increases in multiphoton absorption properties without any loss of optical transparency. This significant improvement in multiphoton absorption performance by incorporation of the organometallic units into the organic π-framework is maintained when the relevant parameters are scaled by molecular weights or number of delocalizable π-electrons. The four-photon absorption cross-section of the most metal-rich dendrimer is an order of magnitude greater than the previous record value.

  16. Rotational averaging of multiphoton absorption cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Friese, Daniel H., E-mail: daniel.h.friese@uit.no; Beerepoot, Maarten T. P.; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, University of Tromsø — The Arctic University of Norway, N-9037 Tromsø (Norway)

    2014-11-28

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  17. Rotational averaging of multiphoton absorption cross sections

    Science.gov (United States)

    Friese, Daniel H.; Beerepoot, Maarten T. P.; Ruud, Kenneth

    2014-11-01

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  18. Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption.

    Science.gov (United States)

    Tanaka, Akiko; Furubayashi, Tomoyuki; Matsushita, Akifumi; Inoue, Daisuke; Kimura, Shunsuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-01-01

    The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na) as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4) and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control) was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules.

  19. Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption

    Science.gov (United States)

    Tanaka, Akiko; Furubayashi, Tomoyuki; Matsushita, Akifumi; Inoue, Daisuke; Kimura, Shunsuke; Katsumi, Hidemasa; Sakane, Toshiyasu; Yamamoto, Akira

    2016-01-01

    The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na) as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4) and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control) was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules. PMID:27598527

  20. Central cooling: absorptive chillers

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.E.

    1977-08-01

    This technology evaluation covers commercially available single-effect, lithium-bromide absorption chillers ranging in nominal cooling capacities of 3 to 1,660 tons and double-effect lithium-bromide chillers from 385 to 1,060 tons. The nominal COP measured at operating conditions of 12 psig input steam for the single-effect machine, 85/sup 0/ entering condenser water, and 44/sup 0/F exiting chilled-water, ranges from 0.6 to 0.65. The nominal COP for the double-effect machine varies from 1.0 to 1.15 with 144 psig entering steam. Data are provided to estimate absorption-chiller performance at off-nominal operating conditions. The part-load performance curves along with cost estimating functions help the system design engineer select absorption equipment for a particular application based on life-cycle costs. Several suggestions are offered which may be useful for interfacing an absorption chiller with the remaining Integrated Community Energy System. The ammonia-water absorption chillers are not considered to be readily available technology for ICES application; therefore, performance and cost data on them are not included in this evaluation.

  1. Ultrafast transient absorption spectroscopy: principles and application to photosynthetic systems.

    Science.gov (United States)

    Berera, Rudi; van Grondelle, Rienk; Kennis, John T M

    2009-01-01

    The photophysical and photochemical reactions, after light absorption by a photosynthetic pigment-protein complex, are among the fastest events in biology, taking place on timescales ranging from tens of femtoseconds to a few nanoseconds. The advent of ultrafast laser systems that produce pulses with femtosecond duration opened up a new area of research and enabled investigation of these photophysical and photochemical reactions in real time. Here, we provide a basic description of the ultrafast transient absorption technique, the laser and wavelength-conversion equipment, the transient absorption setup, and the collection of transient absorption data. Recent applications of ultrafast transient absorption spectroscopy on systems with increasing degree of complexity, from biomimetic light-harvesting systems to natural light-harvesting antennas, are presented. In particular, we will discuss, in this educational review, how a molecular understanding of the light-harvesting and photoprotective functions of carotenoids in photosynthesis is accomplished through the application of ultrafast transient absorption spectroscopy.

  2. The use of derivative and least-squares methods to analyse a polypharmaceutical product by UV spectrophotometry.

    Science.gov (United States)

    Jones, R; Orchard, M J; Hall, K

    1985-01-01

    Derivative UV spectrophotometry is well established for analysing pharmaceutical products containing more than one drug. By contrast, the least-squares method for over-determined systems is rarely used, because it is assumed that measurements at a large number of wavelengths are needed to obtain good results. Both methods have advantages, and their use in combination is useful for analysing polypharmaceuticals. A combination of derivative and least-squares methods was used to analyse tablets containing pseudoephedrine hydrochloride, triprolidine hydrochloride and dextromethorphan hydrobromide. Pseudoephedrine was determined by derivative spectrophotometry. The other drugs were determined by the least-squares method at higher wavelengths where pseudoephedrine does not absorb. Satisfactory precision for the least-squares method was obtained with a manual spectrometer measuring at six wavelengths and calculating the results with a microcomputer.

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

    Science.gov (United States)

    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.

  4. STUDY ON DETERMINATION OF TRACE Cu(Ⅱ) BY DDCT CHELATING RESIN PRECONCENTRATION AND THIN LAYER RESIN PHASE SPECTROPHOTOMETRY

    Institute of Scientific and Technical Information of China (English)

    LI Chunxiang; YAN Yongsheng; SONG Huanyu; WANG Yun

    2006-01-01

    A new method for determination of Cu(Ⅱ) by DDCT chelating resin preconcentration and thin layer resin phase spectrophotometry was developed. The method has a high sensitivity (ε435 =3.6×105 L/mol· cm), which is 33 times higher than that of liquid phase spectrophotometry. It has a good selectivity (most coexisting ions could not influence determination) and an ideal precision [30μg Cu(Ⅱ), n=6, RSD= 1.67%]. The content of Cu(Ⅱ) in water, high purity rare earth and its oxide was determined. The detection limit of Cu(Ⅱ) is 5.3μg/L, and the linear range is 0~7.2 μg/ml. The result is satisfactory.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-12-01

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

  6. Excited-state nonlinear absorption and its description using density matrix theory

    Institute of Scientific and Technical Information of China (English)

    李淳飞; 司金海; 杨淼; 王瑞波; 张雷

    1995-01-01

    A density matrix theory with a ten-energy-level model in the molecular system irradiated bya pulsed laser at non-resonant wavelength is proposed. The reverse saturable absorption under ns and pspulses and the transformation from reverse saturable absorption to saturable absorption under strong ps pulses are described by this model. The correctness of the theoretical model is proved by experiments.

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2011-01-01

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

  9. Estratégias para aumento de sensibilidade em espectrofotometria UV-VIS Strategies to increase sensitivity in UV-VIS spectrophotometry

    Directory of Open Access Journals (Sweden)

    Fábio R. P. Rocha

    2004-10-01

    Full Text Available Spectrophotometry is one of the most widespread analytical techniques due to its simplicity, reliability, and low-cost instrumentation for both direct measurements and coupled to other techniques or processes such as chromatography, electrophoresis and flow analysis. However, the application is often limited by sensitivity. This article describes some advances that greatly improve the performance of spectrophotometric measurements, especially in order to increase sensitivity, including the employment of liquid-core waveguides and solid-phase spectrophotometry.

  10. Quantum-Spillover Enhanced Surface-Plasmonic Absorption at the Interface of Silver and High-Index Dielectrics

    CERN Document Server

    Jin, Dafei; Neuhauser, Daniel; von Cube, Felix; Yang, Yingyi; Sachan, Ritesh; Luk, Ting S; Bell, David C; Fang, Nicholas X

    2015-01-01

    We demonstrate an unexpectedly strong surface-plasmonic absorption at the interface of silver and high-index dielectrics. We show, from first-principles, that due to the lowered metal-to-dielectric work-function at such interface, conduction electrons display a drastic quantum spillover, causing the interfacial electron-hole pair production to become the predominant dissipation channel. The theoretical prediction is supported experimentally by the electron-energy loss spectroscopy and ultraviolet-visible spectrophotometry. This finding can be of fundamental importance in understanding and designing quantum nano-plasmonic devices, which utilize metal-high-index contacts.

  11. Absorption mode FTICR mass spectrometry imaging.

    Science.gov (United States)

    Smith, Donald F; Kilgour, David P A; Konijnenburg, Marco; O'Connor, Peter B; Heeren, Ron M A

    2013-12-03

    Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here, we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image, and then, these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode "Datacubes" for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.

  12. Determination of Benzoyl Peroxide Content in Wheat Flour Based on Spectrophotometry%分光光度法测定小麦面粉中过氧化苯甲酰含量

    Institute of Scientific and Technical Information of China (English)

    张建夫; 任凯; 赵小萍

    2011-01-01

    [目的]用分光光度法测定面粉及面制品中过氧化笨甲酰含量.[方法]在磷酸介质中,过氧化苯甲酰氧化碘化钾生成的碘与淀粉显色,在520 nm波长处有最大吸收峰,建立了淀粉碘化钾体系光度法间接测定微量过氧化苯甲酰的方法.[结果]面粉用无水乙醇溶解通过离心提取过氧化苯甲酰,过氧化苯甲酰的质量浓度在0.032 g/L以内呈线性.[结论]该方法应用于新制小麦面粉中过氧化苯甲酰的测定,回收率在94.3%以上,步骤简单,易操作,现象明显.%[ Objective ]The aim was to determine benzoyl peroxide content in wheat flour and flour products based on spectrophotometry. [ Method] In phosphoric acid medium,potassium iodide oxidized by benzoyl peroxide oxidation,then generated colored iodine and starch,there was maximum absorption peak in 585 nm wavelength,thereby,the starch potassium iodide system spectrophotometry was established to determine benzoyl peroxide. [ Result ] Flour dissolved by ethanol extraction through centrifugal benzoyl peroxid, benzoyl peroxide concentration in the 0.032 g/L or less linearly. [Conclusion]The new method has been applied to wheat flour produced in the determination of benzoyl peroxide,and the recovery is 94.3% and above. The experimental results show that the steps of the method is simple and easy to operate,the phenomenon is obvious.

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

    Science.gov (United States)

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

    1991-03-01

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

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

    Science.gov (United States)

    Khodadoust, Saeid; Ghaedi, Mehrorang

    2014-12-01

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

  15. Lead Quantification in Urine Samples of Athletes by Coupling DLLME with UV-Vis Spectrophotometry.

    Science.gov (United States)

    Faraji, Hakim; Helalizadeh, Masoumeh

    2017-04-01

    Urine lead level is one of the most employed measures of lead exposure and risk. The urine samples used in this study were obtained from ten healthy male cyclists. Dispersive liquid-liquid microextraction combined with ultraviolet and visible spectrophotometry was utilized for preconcentration, extraction, and determination of lead in urine samples. Optimization of the independent variables was carried out based on chemometric methods in three steps. According to the screening and optimization study, 133 μL of CCl4 (extracting solvent), 1.34 mL ethanol (dispersing solvent), pH 2.0, 0.00 % of salt, and 0.1 % O,O-diethyl dithiophosphoric (chelating agent) were used as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R (2) was 0.9991, and linearity range was 0.01-100 μg L(-1). Precision was evaluated in terms of repeatability and intermediate precision, with relative standard deviations being 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.

  16. Determination of Trace Mercury by Cloud Point Extraction Preconcentration Coupled with Spectrophotometry

    Science.gov (United States)

    Sohrabi, Mahmoud Reza; Farokhi, Elham; Adnani, Atena; Ziaian, Mona

    A new micell-mediated phase separation method for preconcentration of ultra-trace quantities of mercury as a prior step to its determination spectrophotometry has been developed. The method is based on the Cloud Point Extraction (CPE) of mercury with Triton X-100 in the absence of chelating agent. Mercury react with sodium diethyldithiocarbamate (DDTC) in a surfactant solution yielding a hydrophobic complex, which then is entrapped in surfactant micelles. Separation of the two phases was accomplished by centrifugation for 10 min at 4000 rpm. Under the optimum conditions i.e., pH 9.0, cloud point temperature 45°C, [DDTC] = 1.6x10-5 mol L-1, [Triton X-114] = 0.032%. Analytical graphs were rectilinear in the concentration range of 4-240 µg L-1 and relative standard deviation for five replicate determinations of Mercury at 8 (μg L-1) concentration level, were 1.9%, respectively (n = 5, c = 8 µg L-1).

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

    Science.gov (United States)

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

    2004-01-01

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

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

    Science.gov (United States)

    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.

  19. Catalytic Spectrophotometry for Vanadium Determination Based on Oxidation of Arsenazo Ⅲ by Bichromate

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A catalytic spectrophotometry for the determination of trace amount of vanadium was developed based on its catalytic effect on the oxidation of arsenazo Ⅲ by potassium bichromate in weak acidic medium. The optimized conditions for determinations are: cK2Cr2O7=3.0×10-5 mol·L-1, carsenazo Ⅲ=3.0×10-5 mol·L-1, pH=4.0, t=90℃. The calibration graph is linear for 0.02~0.2 μg·ml-1, and the detection limit is 0.02 μg·ml-1 V. The apparent active energy of this catalytic reaction is 21.72 kJ·mol-1. Most foreign ions do not interfere with the determination of vadadium, except for Fe(Ⅱ) and Co(Ⅱ), and their interferences could be eliminated by ion exchange. The present method has been used to make the determination of vanadium in human hair, tea, potato and wastewater, and the results were satisfactory.

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

    Science.gov (United States)

    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).

  1. A New Concept for Spectro-photometry of Exoplanets with Space-based Telescopes

    CERN Document Server

    Matsuo, Taro; Shibai, Hiroshi; Sumi, Takahiro; Yamamuro, Tomoyasu

    2015-01-01

    We propose a new concept for spectral characterization of transiting exoplanets with future space-based telescopes. This concept, called as densified pupil spectroscopy, allows us to perform high, stable spectrophotometry against telescope pointing jitter and deformation of the primary mirror instead of not having imaging capability. 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 acquire 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 the pointing...

  2. A New Concept for Spectrophotometry of Exoplanets with Space-borne Telescopes

    Science.gov (United States)

    Matsuo, Taro; Itoh, Satoshi; Shibai, Hiroshi; Sumi, Takahiro; Yamamuro, Tomoyasu

    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 acquire 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.

  3. The UV-VIS spectrophotometry applied to color and stability study in colored mortars

    Directory of Open Access Journals (Sweden)

    Alejandre, F. J.

    1999-06-01

    Full Text Available In the field of methodologies for color studying, a research of it has been done on colored mortars by applying uv-vis spectrophotometry, instrumental technique which can be used for solid materials works, and previously applied to building materials study. Results obtained show that the mentioned technique permits to evaluate quantitatively and qualitatively colors in an easy and objective way, besides nowadays advantages of the instrumental analysis: digital color register, computerized data processing, and precision and exactness increment in chromatic comparisons.

    Dentro de las metodologías existentes para el estudio del color, se ha realizado una investigación del mismo en morteros coloreados por medio de la espectrofotometría UV-VIS, técnica instrumental que es adaptable al trabajo con materiales sólidos, y que ha sido aplicada anteriormente en el estudio de diversos materiales de construcción. Los resultados obtenidos muestran cómo la citada técnica permite además de evaluar cualitativamente y cuantitativamente los colores de forma sencilla y objetiva, el disponer de las ventajas que conlleva actualmente el análisis instrumental: registro digital del color, tratamiento informatizado de datos y aumento de precisión y exactitud en las comparaciones cromáticas.

  4. A new atomic absorption spectral assay for the determination of trace IgG using immunonanogold.

    Science.gov (United States)

    Tang, Yafang; Jiang, Caina; Liang, Aihui; Li, Jishun; Jiang, Zhiliang

    2011-05-01

    Nanogold in size of 10 nm was used to label goat anti-human IgG (GIgG) to obtain an immunonanogold probe (AuGIgG) for IgG. In pH 6.8 phosphate buffer solution and in the presence of immunoprecipitator polyethylene glycol 6000 (PEG 6000), IgG reacted with the probe (AuGIgG) to form AuGIgG-IgG-PEG immunocomplex. After the centrifugation to remove the immunocomplex, AuGIgG in the supernatant can be measured by atomic absorption spectrophotometry at gold absorption line 242.8 nm. The results showed that the absorption value decreased as the concentration of IgG increased, and the decreased absorption value was linear to IgG concentration in the range 0.025-0.375 μg/mL, with a detection limit of 0.008 μg/mL. On this base, a new nanogold-labeled atomic absorption spectral assay for IgG was established. The assay was applied to determine IgG in human serum sample with satisfactory results.

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

    CERN Document Server

    Barnes, J R; Staab, D; Anglada-Escudé, G

    2016-01-01

    We have detected excess absorption in the emission cores of Ca II H & K during transits of HD 189733b for the first time. Using observations of three transits we investigate the origin of the absorption, which is also seen in H{\\alpha} and the Na I D lines. Applying differential spectrophotometry methods to the Ca II H and Ca II K lines combined, using respective passband widths of {\\Delta}{\\lambda} = 0.4 & 0.6 $\\AA$ yields excess absorption of t$_d$ = 0.0074 $\\pm$ 0.0044 (1.7{\\sigma}; Transit 1) and 0.0214 +/- 0.0022 (9.8{\\sigma}; Transit 2). Similarly, we detect excess H{\\alpha} absorption in a passband of width {\\Delta}{\\lambda} = 0.7 $\\AA$, with t$_d$ = 0.0084 $\\pm$ 0.0016 (5.2{\\sigma}) and 0.0121 $\\pm$ 0.0012 (9.9{\\sigma}). For both lines, Transit 2 is thus significantly deeper. Combining all three transits for the Na I D lines yields excess absorption of t$_d$ = 0.0041 $\\pm$ 0.0006 (6.5{\\sigma}). By considering the time series observations of each line, we find that the excess apparent absorptio...

  6. Chemical Absorption Materials

    DEFF Research Database (Denmark)

    Thomsen, Kaj

    2011-01-01

    Chemical absorption materials that potentially can be used for post combustion carbon dioxide capture are discussed. They fall into five groups, alkanolamines, alkali carbonates, ammonia, amino acid salts, and ionic liquids. The chemistry of the materials is discussed and advantages and drawbacks...... are mentioned. References to review papers, papers with experimental data, and papers describing the thermodynamic modelling of the systems are given....

  7. Determination of tylosin phosphate in feed premix by ultraviolet spectrophotometry%紫外分光光度法测定饲料预混剂中磷酸泰乐菌素的含量

    Institute of Scientific and Technical Information of China (English)

    牛纯青; 李振

    2013-01-01

    采用紫外分光光度法测定饲料预混剂中磷酸泰乐菌素的含量.试验结果表明,磷酸泰乐菌素的的最大吸收波长为289 nm,在此波长处,磷酸泰乐菌素的质量浓度在5.0~50.0μg/ml,其吸光度与质量浓度呈现良好的线性关系:A=0.026 9x+0.028 6,R2 =0.999 9(n=6).该方法操作简单快速,结果准确,可用于饲料预混剂中磷酸泰乐菌素含量的测定.%The tylosin phosphate in feed premix was determined by ultraviolet spectrophotometry. The experiment results showed that:the maximum absorption wavelength of tylosin phosphate was 289 nm,and the linearity of absorption was good with concentration in the range of 5. 0~50. 0 μg/ml. The regression equation was:A = 0. 026 9χ+0. 028 6,R2 =0. 999 9(n =6). The method was simple and quick, and accurate, which could be applied into quick determination of tylosin phosphate in feed premix.

  8. The molecular pathway to ZIF-7 microrods revealed by in situ time-resolved small- and wide-angle X-ray scattering, quick-scanning extended X-ray absorption spectroscopy, and DFT calculations.

    Science.gov (United States)

    Goesten, Maarten; Stavitski, Eli; Pidko, Evgeny A; Gücüyener, Canan; Boshuizen, Bart; Ehrlich, Steven N; Hensen, Emiel J M; Kapteijn, Freek; Gascon, Jorge

    2013-06-10

    We present an in situ small- and wide-angle X-ray scattering (SAXS/WAXS) and quick-scanning extended X-ray absorption fine-structure (QEXAFS) spectroscopy study on the crystallization of the metal-organic framework ZIF-7. In combination with DFT calculations, the self-assembly and growth of ZIF-7 microrods together with the chemical function of the crystal growth modulator (diethylamine) are revealed at all relevant length scales, from the atomic to the full crystal size.

  9. Carbohydrate-based switch-on molecular sensor for Cu(II) in buffer: absorption and fluorescence study of the selective recognition of Cu(II) ions by galactosyl derivatives in HEPES buffer.

    Science.gov (United States)

    Singhal, Nitin Kumar; Ramanujam, Balaji; Mariappanadar, Vairamani; Rao, Chebrolu Pulla

    2006-08-03

    [graph: see text] 1-(Beta-D-galactopyranosyl-1'-deoxy-1'-iminomethyl)-2-hydroxynaphthalene (L1), possessing an ONO binding core, was found to be selective for Cu2+ ions in N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid] buffer, at concentrations < or = 580 ppb, at physiological pH by eliciting switch-on behavior, whereas the other ions, viz., Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Zn2+, and Cd2+, caused no significant change in the fluorescence. Whereas the binding characteristics were ascertained by absorption spectroscopy, the species formed were shown by Q-TOF ES MS.

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

    Science.gov (United States)

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

    2016-10-01

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

  11. Acoustic absorption by sunspots

    Science.gov (United States)

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

    1987-01-01

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

  12. Chaotic systems with absorption

    CERN Document Server

    Altmann, Eduardo G; Tél, Tamás

    2013-01-01

    Motivated by applications in optics and acoustics we develop a dynamical-system approach to describe absorption in chaotic systems. We introduce an operator formalism from which we obtain (i) a general formula for the escape rate $\\kappa$ in terms of the natural conditionally-invariant measure of the system; (ii) an increased multifractality when compared to the spectrum of dimensions $D_q$ obtained without taking absorption and return times into account; and (iii) a generalization of the Kantz-Grassberger formula that expresses $D_1$ in terms of $\\kappa$, the positive Lyapunov exponent, the average return time, and a new quantity, the reflection rate. Simulations in the cardioid billiard confirm these results.

  13. FTIR (Fourier Transform Infrared) spectrophotometry for thin film monitors: Computer and equipment integration for enhanced capabilities

    Science.gov (United States)

    Cox, J. N.; Sedayao, J.; Shergill, G.; Villasol, R.; Haaland, D. M.

    Fourier transform infrared spectrophotometry (FTIR) is a valuable technique for monitoring thin films used in semiconductor device manufacture. Determinations of the constituent contents in borophosphosilicate (BPSG), phosphosilicate (PSG), silicon oxynitride (SiON:H,OH), and spin-on-glass (SOG) thin films are a few applications. Due to the nature of the technique, FTIR instrumentation is one of the most extensively computer-dependent pieces of equipment that is likely to be found in a microelectronics plant. In the role of fab monitor or reactor characterization tool, FTIR instruments can rapidly generate large amounts of data. By linking a local FTIR data station to a remote minicomputer its capabilities are greatly improved. We discuss three caused of enhancement. First, the FTIR in the fab area communicates and interacts in real time with the minicomputer: transferring data segments to it, instructing it to perform sophisticated processing, and returning the result to the operator in the fab. Characterizations of PSG thin films by this approach are discussed. Second, the spectra of large numbers of samples are processed locally. The large database is then transmitted to the minicomputer for study by statistical/graphics software. Results of CVD-reactor spatial profiling experiments for plasma SiON are presented. Third, processing of calibration spectra is performed on the minicomputer to optimize the accuracy and precision of a Partial Least Squares analysis mode. This model is then transferred to the data station in the fab. The analysis of BPSG thin films is discussed in this regard. The prospects for fully automated at-line monitoring and for real-time, in-situ monitoring will be discussed.

  14. FTIR (Fourier transform infrared) spectrophotometry for thin film monitors: Computer and equipment integration for enhanced capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Cox, J.N.; Sedayao, J.; Shergill, G.; Villasol, R. (Intel Corp., Santa Clara, CA (USA)); Haaland, D.M. (Sandia National Labs., Albuquerque, NM (USA))

    1990-01-01

    Fourier transform infrared spectrophotometry (FTIR) is a valuable technique for monitoring thin films used in semiconductor device manufacture. Determinations of the constituent contents in borophosphosilicate (BPSG), phosphosilicate (PSG), silicon oxynitride (SiON:H,OH), and spin-on-glass (SOG) thin films are a few applications. Due to the nature of the technique, FTIR instrumentation is one of the most extensively computer-dependent pieces of equipment that is likely to be found in a microelectronics plant. In the role of fab monitor or reactor characterization tool, FTIR instruments can rapidly generate large amounts of data. By linking a local FTIR data station to a remote minicomputer its capabilities are greatly improved. We discuss three caused of enhancement. First, the FTIR in the fab area communicates and interacts in real time with the minicomputer: transferring data segments to it, instructing it to perform sophisticated processing, and returning the result to the operator in the fab. Characterizations of PSG thin films by this approach are discussed. Second, the spectra of large numbers of samples are processed locally. The large database is then transmitted to the minicomputer for study by statistical/graphics software. Results of CVD-reactor spatial profiling experiments for plasma SiON are presented. Third, processing of calibration spectra is performed on the minicomputer to optimize the accuracy and precision of a Partial Least Squares'' analysis mode. This model is then transferred to the data station in the fab. The analysis of BPSG thin films is discussed in this regard. The prospects for fully automated at-line monitoring and for real-time, in-situ monitoring will be discussed. 10 refs., 4 figs.

  15. Spectrophotometry and the Development of Emissions for Comet Hyakutake 1996 B2

    Science.gov (United States)

    Hicks, M.; Fink, U.

    1996-09-01

    An analysis of our spectrophotometry of Comet Hyakutake 1996 B2 from 0.55 mu m to 1.05 mu m obtained between February 17 and April 17 1996 is presented. We derive Afrho values and production rates of H_2O, C_2, NH_2, and CN. In general we find the Haser model to be substantiated with no inconsistencies for different aperture sizes and different heliocentric and geocentric distances. Comet Hyakutake is the dustiest comet in our database of 39 comets (Fink and Hicks 1996) and both the dust and the H_2O production rates follow a heliocentric dependence of ~ r(-1.5) , lower than the ~ r(-2.5) dependence found for P/Halley (Fink 1994). The Afrho values and the H_2O production rates track the visual lightcurve quite well. Strong evidence for quenching of OI emissions close to the nucleus was observed during the March data due to the comet's small geocentric distance. While the CN production rate also has a dependence of ~ r(-1.5) with a CN/H_2O ratio typical of most comets, the C_2 production rate has a much steeper slope, ~ r(-2.5) , and the C_2/H_2O ratio evolves from a typical cometary ratio to one that is exceedingly rich in C_2. We feel that this is evidence for a significant CHON contribution to the overall C_2 production. The NH_2 production is considerably flatter and follows roughly a ~ r(-0.85) law. In February and March, Hyakutake exhibits the highest relative NH_2 abundance of any comet in our database, but reverts to more a normal value in April. All together, we feel that the behavior of the comet's Afrho and production rates throughout its apparition argue for a more primordial comet than may be suggested by the orbital elements alone.

  16. Comparison of body composition assessment by hydrodensitometry, skinfolds, and multiple site near-infrared spectrophotometry.

    Science.gov (United States)

    Hortobágyi, T; Israel, R G; Houmard, J A; McCammon, M R; O'Brien, K F

    1992-03-01

    Percent body fat (%BF) was assessed in 171 men with underwater weighing (UWW), seven-site skinfolds (7 SF), and near-infrared spectrophotometry (NIR). NIR was determined at eight sites, including biceps, triceps, axilla, chest, abdomen, suprailium, subscapula and thigh. Analysis of variance and Dunnett's post-hoc procedure revealed that NIR significantly (P less than 0.05) underpredicted %BF when using the biceps (12.9%), chest (11.3%), abdomen (10.2%), subscapula (11.3%) and thigh (9.9%) sites compared to the criterion %BF measured with UWW (13.4% +/- SD = 6.49). %BF with 7 SF was only 0.3% higher than %BF with UWW (r = 0.94, standard error of estimate = 2.9%). Correlation coefficients between SF thickness and NIR optical density readings at 940 nm (OD1) and 950 nm (OD2) wavelengths ranged from r = -0.30 (subscapula) to r = -0.67 (biceps) for OD1 and r = -0.39 (axilla) to r = -0.68 (biceps) for OD2. Multiple linear regression showed that the OD readings were not significant predictors of UWW %BF when using body mass, stature, activity level, and frame size as predictors, except for the OD2 reading at the biceps site. Stepwise regression revealed that NIR OD readings did not predict additional variance in %BF beyond mass, stature, activity level, frame size, or 7 SF. It was concluded that 7 SF are better predictors of %BF than NIR, and that NIR at multiple sites is inconsistent in assessing body composition.

  17. Determination of crystal violet in water by direct solid phase spectrophotometry after rotating disk sorptive extraction.

    Science.gov (United States)

    Manzo, Valentina; Navarro, Orielle; Honda, Luis; Sánchez, Karen; Inés Toral, M; Richter, Pablo

    2013-03-15

    The microextraction of crystal violet (CV) from water samples into polydimethylsiloxane (PDMS) using the rotating disk sorptive extraction (RDSE) technique was performed. The extracting device was a small Teflon disk that had an embedded miniature magnetic stirring bar and a PDMS (560 μL) film attached to one side of the disk using double-sided tape. The extraction involves a preconcentration of CV into the PDMS, where the analyte is then directly quantified using solid phase spectrophotometry at 600 nm. Different chemical and extraction device-related variables were studied to achieve the best sensitivity for the determination. The optimum extraction was performed at pH 14 because under this condition, CV is transformed to the neutral and colorless species carbinol, which can be quantitatively transferred to the PDMS phase. Although the colorless species is the chemical form extracted in the PDMS, an intense violet coloration appeared in the phase because the -OH bond in the carbinol molecule is weakened through the formation of hydrogen bonds with the oxygen atoms of the PDMS, allowing the resonance between the three benzene rings to compensate for the charge deficit on the central carbon atom of the molecule. The accuracy and precision of the method were evaluated in river water samples spiked with 10 and 30 μg L(-1) of CV, yielding a relative standard deviation of 6.2% and 8.4% and a recovery of 98.4% and 99.4%, respectively. The method detection limit was 1.8 μg L(-1) and the limit of quantification was 5.4 μg L(-1), which can be decreased if the sample volume is increased.

  18. Estimation of nitrite in source-separated nitrified urine with UV spectrophotometry.

    Science.gov (United States)

    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.

  19. Photoinduced absorption of polyalkylthienylenevinylenes

    Energy Technology Data Exchange (ETDEWEB)

    Botta, C. (Ist. di Chimica delle Macromolecole (CNR), Milano (Italy)); Bradley, D.D.C. (Cambridge Univ. (United Kingdom). Cavendish Lab.); Friend, R.H. (Cambridge Univ. (United Kingdom). Cavendish Lab.); Musco, A. (Ist. di Scienze Chimiche, Univ. di Urbino (Italy))

    1993-03-15

    We present a photoinduced absorption study of alkyl substituted poly(2,5-thienylenevinylene)s. Three photoinduced states are detected in both the solid state and in solution. The two low-energy bands are assigned to bipolarons, while a third band peaked near the band edge has a different origin. In solution photoexcitated states are very long-lived and we propose that photoexcitation recombine via a solvent-assisted photo-doping mechanism. (orig.)

  20. Hydrogen Absorption by Niobium.

    Science.gov (United States)

    1982-04-13

    incorporate an independent means for ascertaining surface cleanliness (e.g. AES). The form of the absorption curve in Fig. 7 appears to agree with that...very interesting study and is well within the capabilities of the systen designed, if the surface cleanliness can be assured. Wire specimens have a...assessing surface cleanliness would be an important supporting technique for understanding the results of these measurements. The simple kinetic