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Sample records for photometric titration procedure

  1. Instrumentation and automated photometric titration procedure for total acidity determination in red wine employing a multicommuted flow system.

    PubMed

    Garcia, Ausberta Jesus Cabezas; Reis, Boaventura F

    2006-01-01

    An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca 2% (n=9) was obtained when processing a typical red wine sample containing 7.3 gl-1 total acidity expressed as tartaric acid.

  2. Instrumentation and automated photometric titration procedure for total acidity determination in red wine employing a multicommuted flow system.

    PubMed

    Garcia, Ausberta Jesus Cabezas; Reis, Boaventura F

    2006-01-01

    An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca 2% (n=9) was obtained when processing a typical red wine sample containing 7.3 gl-1 total acidity expressed as tartaric acid. PMID:17671625

  3. A full automatic device for sampling small solution volumes in photometric titration procedure based on multicommuted flow system.

    PubMed

    Borges, Sivanildo S; Vieira, Gláucia P; Reis, Boaventura F

    2007-01-01

    In this work, an automatic device to deliver titrant solution into a titration chamber with the ability to determine the dispensed volume of solution, with good precision independent of both elapsed time and flow rate, is proposed. A glass tube maintained at the vertical position was employed as a container for the titrant solution. Electronic devices were coupled to the glass tube in order to control its filling with titrant solution, as well as the stepwise solution delivering into the titration chamber. The detection of the titration end point was performed employing a photometer designed using a green LED (lambda=545 nm) and a phototransistor. The titration flow system comprised three-way solenoid valves, which were assembled to allow that the steps comprising the solution container loading and the titration run were carried out automatically. The device for the solution volume determination was designed employing an infrared LED (lambda=930 nm) and a photodiode. When solution volume delivered from proposed device was within the range of 5 to 105 mul, a linear relationship (R = 0.999) between the delivered volumes and the generated potential difference was achieved. The usefulness of the proposed device was proved performing photometric titration of hydrochloric acid solution with a standardized sodium hydroxide solution and using phenolphthalein as an external indicator. The achieved results presented relative standard deviation of 1.5%. PMID:18317510

  4. A Low-Cost Device for Automatic Photometric Titrations

    NASA Astrophysics Data System (ADS)

    Rocha, Fábio R. P.; Reis, Boaventura F.

    2000-02-01

    Electronics is an important topic in chemistry courses. However, the introduction of basic concepts is often difficult and the lab instruments are frequently seen as "black boxes". To address this problem, we propose the construction of a simple, low-cost (about $150 U.S.) automatic photometric titrator employing a light-emitting diode (LED) and a phototransistor. The electronic circuit can be assembled by the students themselves. The device was employed to implement a common procedure in chemical labs, making feasible the introduction of concepts related to electronics in undergraduate chemistry courses. The titrator is able to work automatically, since a feedback system permits stopping the addition of titrant solution when the end-point is achieved. With this demonstration, it can be stressed that automatic procedures can be implemented without expensive instruments. Additionally, a classical procedure becomes more attractive to the students and its importance to chemical analysis can be emphasized. The feasibility of the titrator was demonstrated by acid-base titrations of HCl solutions with NaOH in the presence of phenolphthalein and by iodimetric determination of ascorbic acid in vitamin C tablets and lemon juice. Precise results (0.7% relative standard deviation, n = 10) in agreement at the 95% confidence level with those attained by a conventional procedure were obtained.

  5. Determination of lanthanum by flame photometric titration.

    PubMed

    Svehla, G; Slevin, P J

    1968-09-01

    The flame emission of lanthanum at 560 mmu decreases linearly with phosphate concentration until a 1:1 molar ratio is reached, and then remains practically constant. Lanthanum can be titrated with phosphate, the equivalence point being detected from the change in emission intensity. Errors due to consumption of solution by the atomizer can be kept low by using short spraying times and low galvanometer damping. The average error is about -1% for 0.1M solutions and less than -5% for 0.01M. The method gives good results in the presence of titanium(III), zirconium, thorium and aluminium but cerium(III) and yttrium seriously interfere. PMID:18960392

  6. Acid-base titrations by stepwise addition of equal volumes of titrant with special reference to automatic titrations-IV Photometric titration of an acid.

    PubMed

    Pehrsson, L; Ingman, F

    1977-02-01

    In Part I of this series, evaluation methods for potentiometric titrations of acids performed by stepwise addition of titrant were introduced. These methods are non-approximative and may therefore in principle be applied to titrations of acids of any strength. This paper demonstrates that photometric titrations performed by stepwise addition of titrant may also be evaluated by the proposed methods. The photometric method is compared with the potentiometric method of monitoring the course of a titration.

  7. Automatic photometric titrations of calcium and magnesium in carbonate rocks

    USGS Publications Warehouse

    Shapiro, L.; Brannock, W.W.

    1955-01-01

    Rapid nonsubjective methods have been developed for the determination of calcium and magnesium in carbonate rocks. From a single solution of the sample, calcium is titrated directly, and magnesium is titrated after a rapid removal of R2O3 and precipitation of calcium as the tungstate. A concentrated and a dilute solution of disodium ethylenediamine tetraacetate are used as titrants. The concentrated solution is added almost to the end point, then the weak solution is added in an automatic titrator to determine the end point precisely.

  8. [Photometric micro-titration model of DPPH radicals scavenging activity and its application].

    PubMed

    Gao, Yun-tao; Wei, Wei; Ye, Li-qing; Li, Xiao-fen; Liu, Ping; Zhang, Hong-jiao; Yang, Lu; Yu, Jiao-jiao; Cha, Jia-wei

    2015-02-01

    In the present paper, the stoichiometric ratio (R) for the interreaction of DPPH radicals with the antoxidant was employed as a evaluation index for DPPH radicals scavenging activity of antioxidants. This evaluation index was related only with the stoichiometric relationship between DPPH radicals and the antioxidant, not the relationship with the initial DPPH amount and the volume of sample, which could offer a solution for the problem of poor comparability of EC50 under different conditions. A novel photometric micro-titration method was proposed for the determination of the stoichiometric ratio (R) for the interreaction of DPPH radicals with the antoxidant. The titration equation was established based on the absorbance difference (deltaA) of DPPH radicals in the titration process and the added amount of antoxidant. The stoichiometric ratio (R) for the reaction of DPPH radicals with the addition amount of antoxidant was determined by the titration equation obtained, while, the DPPH median elimination concentration (EC50) of antoxidant can be calculated by the stoichiometric ratio (R). The above photometric micro-titration model was verified using rutin as DPPH radicals scavenger. As experiment results, the stoichiometric ratio (R) of DPPH radicals to rutin was determined to be in the range of 1.817-1.846. The calculated value of EC50 was 1.196 x 10(-3), 2.392 x 10(-3), 4.819 x 10(-3) and 7.292 x 10(-3) mg x mL(-1) for 1.12 x 10(-7), 2.24 x 10(-7), 4.48 x 10(-7) and 6.72 x 10(-7) mol of the additon amount of DPPH radicals, respectively. The proposed method has better precision and reliability with smaller amount of sample than conventional method. While, the obtained stoichiometric ratio value (R) of rutin was employed to calculate the rutin median elimination concentration for DPPH EC50) according to the conditions as reported in the literatures, and the calculated results were consistent with that reported in the literatures.

  9. Scopolamine Effects Under a Titrating-Delayed-Nonmatching-to-Position Procedure

    ERIC Educational Resources Information Center

    Porritt, M.; Poling, A.

    2008-01-01

    In a study of working memory, the performance of rats under titrating-delayed-nonmatching- to-position (TDNMTP) procedures was examined. Overall accuracy and the number of trials completed were inversely related to titration value, whereas the highest delay attained was directly related to titration value. When given intraperitoneally,…

  10. Computer-assisted Gran titration procedure for strong acid determination

    SciTech Connect

    Phillips, M.F.; Gaffney, J.S.; Goodrich, R.W.; Tanner, R.L.

    1984-10-01

    An automated method for determining, by coulometric titration, small amounts of strong acid in the presence of weak acids is given. Essentially, a pH meter and a coulometer are coupled with a Tektronix 4052 mini-computer, and a two-step computer program then directs the titration and calculates the equivalence point by the method of Gran. A comparison of precision and accuracy of results for test solutions by manual and automated data reduction methods is presented. The method is being used successfully to analyze for the H/sup +/ content in ambient aerosol samples from aerometric field experiments, and can be used for cloud and rainwater samples as well. 3 references, 1 figure, 1 table.

  11. Comparison of VFA titration procedures used for monitoring the biogas process.

    PubMed

    Lützhøft, Hans-Christian Holten; Boe, Kanokwan; Fang, Cheng; Angelidaki, Irini

    2014-05-01

    Titrimetric determination of volatile fatty acids (VFAs) contents is a common way to monitor a biogas process. However, digested manure from co-digestion biogas plants has a complex matrix with high concentrations of interfering components, resulting in varying results when using different titration procedures. Currently, no standardized procedure is used and it is therefore difficult to compare the performance among plants. The aim of this study was to evaluate four titration procedures (for determination of VFA-levels of digested manure samples) and compare results with gas chromatographic (GC) analysis. Two of the procedures are commonly used in biogas plants and two are discussed in literature. The results showed that the optimal titration results were obtained when 40 mL of four times diluted digested manure was gently stirred (200 rpm). Results from samples with different VFA concentrations (1-11 g/L) showed linear correlation between titration results and GC measurements. However, determination of VFA by titration generally overestimated the VFA contents compared with GC measurements when samples had low VFA concentrations, i.e. around 1 g/L. The accuracy of titration increased when samples had high VFA concentrations, i.e. around 5 g/L. It was further found that the studied ionisable interfering components had lowest effect on titration when the sample had high VFA concentration. In contrast, bicarbonate, phosphate and lactate had significant effect on titration accuracy at low VFA concentration. An extended 5-point titration procedure with pH correction was best to handle interferences from bicarbonate, phosphate and lactate at low VFA concentrations. Contrary, the simplest titration procedure with only two pH end-points showed the highest accuracy among all titration procedures at high VFA concentrations. All in all, if the composition of the digested manure sample is not known, the procedure with only two pH end-points should be the procedure of

  12. Acid-base properties of the alumina surface: influence of the titration procedures on the microcalorimetric results.

    PubMed

    Morel, Jean-Pierre; Marmier, Nicolas; Hurel, Charlotte; Morel-Desrosiers, Nicole

    2009-10-01

    The enthalpy changes associated with the protonation and deprotonation of an alumina surface have been determined on the basis of microcalorimetry experiments and acid-base potentiometric titrations at 25 degrees C. It has been shown that the results may vary significantly according to the experimental procedure. In order to do so, the potentiometric and microcalorimetric titrations have been carried out first from an acidic pH to basic pH and second from a pH near the pH(zpc) of alumina to acidic or basic pH. It has been demonstrated that the pK(a) values deduced from the potentiometric titrations are the same whatever the experimental protocol whereas the only way to obtain meaningful enthalpies of proton exchange is to carry out microcalorimetric titrations by starting around the point of zero charge.

  13. Kinetics of reactions of antihemagglutinin and antineuraminidase antibodies with H2N2 and H3N2 influenza virus strains and description of a modification of the photometric ACU method for titration of antineuraminidase antibodies.

    PubMed

    Drescher, J; Desselberger, U

    1976-01-01

    The isotherms describing the reactions of selected H2N2 and H3N2 virus strains with antihemagglutinin (AH) and antineuraminidase (AN) antibodies were established by use of a photometric hemagglutination inhibition test [antibody concentration unit (ACU) method]. It was found that the AN antibody isotherms had significantly higher values of the constant 1/N than did the AH antibody isotherms. This finding confirms for further virus strains the conclusion that the photometric ACU method can discriminate objectively between AN and AH antibodies. The results obtained when determining by use of the photometric ACU method the kinetics of reactions of AN antibodies oriented to A/Bel (HO)-A/Sing (N2) virus with the neuraminidases of H2N2 and H3N2 strains, and vice versa, indicated that the N2 neuraminidases of the test strains could be divided into the following groups: One group comprising the strains A/Sing/1/57 and A/AA/1/65, a second comprising the strains A/Hong Kong/1/68 and A/England/42/72 and a third represented by A/Port Chalmers/1/73. This finding indicated progressive antigenic variation of the neuraminidases of the strains tested. A modification of the photometric ACU method for the titration of AN antibodies oriented to N2 strains has been developed. The modified technique was found to be more sensitive and accurate than was AN antibody titration by means of enzyme inhibition and HI pattern test.

  14. Procedure for the quantitative determination of mixtures of nucleic Acid components based on multivariate spectrophotometric Acid-base titrations.

    PubMed

    Saurina, J; Hernández-Cassou, S; Tauler, R; Izquierdo-Ridorsa, A

    1999-01-01

    A new procedure for the quantitative determination of mixtures of nucleic acid components, based on continuous spectrophotometric acid-base titrations and multivariate curve resolution, is proposed. The procedure simultaneously takes into account the spectroscopic and acid-base properties of the compounds, which leads to a higher selectivity. Furthermore, quantitative determination of an analyte in a complex mixture is performed using a synthetic solution as standard containing only the analyte of interest. An intrinsic difficulty in the analysis of spectrometric titration data is the presence of rank deficiency due to closure for the mixtures of two or more compounds. An additional problem can be encountered in some mixtures if species spectra or species concentration profiles are practically identical (rank overlap). However, even in the presence of these rank difficulties, accurate quantitation with prediction errors lower than 5% was obtained. The presence of unknown and uncalibrated interferences in the samples does not affect the quantitative determination of the analyte of interest. The proposed procedure was successfully applied to the analysis of real samples (pharmaceuticals) using synthetic external standards.

  15. The Nature, Significance, and Evaluation of the Schwarzschild-Villiger (SV) Effect in Photometric Procedures

    PubMed Central

    Howling, D. H.; Fitzgerald, P. J.

    1959-01-01

    The Schwarzschild-Villiger effect has been experimentally demonstrated with the optical system used in this laboratory. Using a photographic mosaic specimen as a model, it has been shown that the conclusions of Naora are substantiated and that the SV effect, in large or small magnitude, is always present in optical systems. The theoretical transmission error arising from the presence of the SV effect has been derived for various optical conditions of measurement. The results have been experimentally confirmed. The SV contribution of the substage optics of microspectrophotometers has also been considered. A simple method of evaluating a flare function f(A) is advanced which provides a measure of the SV error present in a system. It is demonstrated that measurements of specimens of optical density less than unity can be made with less than 1 per cent error, when using illuminating beam diameter/specimen diameter ratios of unity and uncoated optical surfaces. For denser specimens it is shown that care must be taken to reduce the illuminating beam/specimen diameter ratio to a value dictated by the magnitude of a flare function f(A), evaluated for a particular optical system, in order to avoid excessive transmission error. It is emphasized that observed densities (transmissions) are not necessarily true densities (transmissions) because of the possibility of SV error. The ambiguity associated with an estimation of stray-light error by means of an opaque object has also been demonstrated. The errors illustrated are not necessarily restricted to microspectrophotometry but may possibly be found in such fields as spectral analysis, the interpretation of x-ray diffraction patterns, the determination of ionizing particle tracks and particle densities in photographic emulsions, and in many other types of photometric analysis. PMID:14403512

  16. Isothermal titration calorimetric procedure to determine protein-metal ion binding parameters in the presence of excess metal ion or chelator.

    PubMed

    Nielsen, Anders D; Fuglsang, Claus C; Westh, Peter

    2003-03-15

    Determination of binding parameters for metal ion binding to proteins usually requires preceding steps to remove protein-bound metal ions. Removal of bound metal ions from protein is often associated with decreased stability and inactivation. We present two simple isothermal titration calorimetric procedures that eliminate separate metal ion removal steps and directly monitor the exchange of metal ions between buffer, protein, and chelator. The concept is to add either excess chelator or metal ion to the protein under investigation and subsequently titrate with metal ion or chelator, respectively. It is thereby possible in the same experimental trial to obtain both chelator-metal ion and protein-metal ion binding parameters due to the different thermodynamic "fingerprints" of chelator and protein. The binding models and regression routines necessary to analyze the corresponding binding isotherms have been constructed. Verifications of the models have been done by titrations of mixtures of calcium chelators (BAPTA, HEDTA, and EGTA) and calcium ions and they were both able to account satisfactorily for the observed binding isotherms. Therefore, it was possible to determine stoichiometric and thermodynamic binding parameters. In addition, the concept has been tested on a recombinant alpha-amylase from Bacillus halmapalus where it proved to be a consistent procedure to obtain calcium binding parameters.

  17. Digital image-based titrations.

    PubMed

    Gaiao, Edvaldo da Nobrega; Martins, Valdomiro Lacerda; Lyra, Wellington da Silva; de Almeida, Luciano Farias; da Silva, Edvan Cirino; Araújo, Mário César Ugulino

    2006-06-16

    The exploitation of digital images obtained from a CCD camera (WebCam) as a novel instrumental detection technique for titration is proposed for the first time. Named of digital image-based (DIB) titration, it also requires, as a traditional titration (for example, spectrophotometric, potentiometric, conductimetric), a discontinuity in titration curves where there is an end point, which is associated to the chemical equivalence condition. The monitored signal in the DIB titration is a RGB-based value that is calculated, for each digital image, by using a proposed procedure based on the red, green, and blue colour system. The DIB titration was applied to determine HCl and H3PO4 in aqueous solutions and total alkalinity in mineral and tap waters. Its results were compared to the spectrophotometric (SPEC) titration and, by applying the paired t-test, no statistic difference between the results of both methods was verified at the 95% confidence level. Identical standard deviations were obtained by both titrations in the determinations of HCl and H3PO4, with a slightly better precision for DIB titration in the determinations of total alkalinity. The DIB titration shows to be an efficient and promising tool for quantitative chemical analysis and, as it employs an inexpensive device (WebCam) as analytical detector, it offers an economically viable alternative to titrations that need instrumental detection.

  18. [Laboratory procedures in adenoviruses. II. Sensitivity of various cell cultures as determined by endpoint titration (author's transl)].

    PubMed

    Wigand, R; Schulz, R

    1975-01-01

    The sensitivity of human embryonic kidney (HEK), human amnion (HAm) and HeLa cells for human adenoviruses was investigated by means of endpoint titrations of 13 prototype strains and numerous original specimens from patients. Prototypes and original specimens showed the same behavior. Adenoviruses of subgrouppp III produced nearly identical titers in all 3 cell cultures, while for subgroup I HAm cells showed a 10- to 100-fold lower titer. On the other hand, HAm cells are nearly as sensitive as HEK cells for type 8, whereas HeLa cells are less sensitive. For other viruses of subgroup II and for subgrou IV, HAm (for type 12 also HeLa) cells are less sensitive than HEK cells. Out of three HeLa cell strains tested the Bristol strain was inferior to the other two in its sensitivity. Concerning the speed of the CPE development, HEK cells are superior for all types, the difference being greatest for subgroup I towards HAm and HeLa and for type 8 towards HeLa cells. The length of incubation necessary for the appearance of CPE even with minimal amounts of virus is 40 days for type 8 in all kinds of cell cultures, whereas for adenoviruses of sub-groups I and III, which are predominantly isolated in the routine laboratory, 25 days for HEK and 30 days for HAm and HeLa cells may suffice in most cases. When endpoint titrations are compared with titers obtained by immunofluorescence, it appears that this technique may be applied as a screening method; thus long incubation periods of negative specimens can be saved. The amounts of infectious virus present in original specimens are reported; the highest quantity was found in specimens containing subgroup I viruses.

  19. Microscale Titration in Schools Titration Competition.

    ERIC Educational Resources Information Center

    Clark, Michael J.

    1998-01-01

    Reviews the requirements of the National Titration Competition and describes how a team in a local competition used the technique. Compares microscale titration to conventional titration. Outlines the benefits of employing microscale techniques. (DDR)

  20. Video Observations Encompassing the 2002 Leonid Storm: First Results and a Revised Photometric Procedure for Video Meteor Analysis

    NASA Technical Reports Server (NTRS)

    Cooke, William J.; Suggs, Robert M.; Swift, Wesley; Gural, Peter S.; Brown, Peter; Parker, Nelson C. (Technical Monitor)

    2002-01-01

    During the 2001 Leonid storm, Marshall Space Flight Center, with the cooperation of the University of Western Ontario and the United States Air Force, deployed 6 teams of observers equipped with intensified video systems to sites located in North America, the Pacific, and Mongolia. The campaign was extremely successful, with the entire period of enhanced Leonid activity (over 16 hours) captured on video tape in a consistent manner. We present the first results from the analysis of this unique, 2 terabyte data set and discuss the problems involved in reducing large amounts of video meteor data. In particular, the question of how to determine meteor masses though photometric analysis will be re-examined, and new techniques will be proposed that eliminate some of the deficiencies suffered by the techniques currently employed in video meteor analysis.

  1. Convergence-optimized procedure for applying the NICA-Donnan model to potentiometric titrations of humic substances.

    PubMed

    Lenoir, Thomas; Matynia, Anthony; Manceau, Alain

    2010-08-15

    Despite the high success of the NICA-Donnan (N-D) model to describe the interaction of protons and metal ions with natural organic matter, the large number of fit parameters is a major hindrance to its capacity to provide unique numerical solutions. This well-known difficulty is reflected in the unusually low value of the generic proton binding constant for carboxylic-type groups of fulvic acid (pK(H1) = 2.34), and to some extent of humic acid (2.93), and by the considerable covariance of the other generic N-D parameters. In some studies, the number of parameters obtained by regression is reduced by estimating some values independently with other techniques. Alternatively, the applicability of the model can be improved by devising a rigorous simulation procedure, which constrains the model-fit to converge toward chemically and physically realistic values. A procedure based on three successive iterations is proposed, and the solution is shown to be stable and invariant with the initial set of parameter values. The new generic parameters, in particular pK(H1)(FA) = 3.54 and pK(H1)(HA) = 3.87, derived from the same data set as the previous generic parameters, are in better agreement with literature data.

  2. Tracer-monitored flow titrations.

    PubMed

    Sasaki, Milton K; Rocha, Diogo L; Rocha, Fábio R P; Zagatto, Elias A G

    2016-01-01

    The feasibility of implementing tracer-monitored titrations in a flow system is demonstrated. A dye tracer is used to estimate the instant sample and titrant volumetric fractions without the need for volume, mass or peak width measurements. The approach was applied to spectrophotometric flow titrations involving variations of sample and titrant flow-rates (i.e. triangle programmed technique) or concentration gradients established along the sample zone (i.e. flow injection system). Both strategies required simultaneous monitoring of two absorbing species, namely the titration indicator and the dye tracer. Mixing conditions were improved by placing a chamber with mechanical stirring in the analytical path aiming at to minimize diffusional effects. Unlike most of flow-based titrations, the innovation is considered as a true titration, as it does not require a calibration curve thus complying with IUPAC definition. As an application, acidity evaluation in vinegars involving titration with sodium hydroxide was selected. Phenolphthalein and brilliant blue FCF were used as indicator and dye tracer, respectively. Effects of sample volume, titrand/titrant concentrations and flow rates were investigated aiming at improved accuracy and precision. Results were reliable and in agreement with those obtained by a reference titration procedure.

  3. Tracer-monitored flow titrations.

    PubMed

    Sasaki, Milton K; Rocha, Diogo L; Rocha, Fábio R P; Zagatto, Elias A G

    2016-01-01

    The feasibility of implementing tracer-monitored titrations in a flow system is demonstrated. A dye tracer is used to estimate the instant sample and titrant volumetric fractions without the need for volume, mass or peak width measurements. The approach was applied to spectrophotometric flow titrations involving variations of sample and titrant flow-rates (i.e. triangle programmed technique) or concentration gradients established along the sample zone (i.e. flow injection system). Both strategies required simultaneous monitoring of two absorbing species, namely the titration indicator and the dye tracer. Mixing conditions were improved by placing a chamber with mechanical stirring in the analytical path aiming at to minimize diffusional effects. Unlike most of flow-based titrations, the innovation is considered as a true titration, as it does not require a calibration curve thus complying with IUPAC definition. As an application, acidity evaluation in vinegars involving titration with sodium hydroxide was selected. Phenolphthalein and brilliant blue FCF were used as indicator and dye tracer, respectively. Effects of sample volume, titrand/titrant concentrations and flow rates were investigated aiming at improved accuracy and precision. Results were reliable and in agreement with those obtained by a reference titration procedure. PMID:26703261

  4. Photometric microdetermination of malathion

    USGS Publications Warehouse

    Kallman, B.J.

    1962-01-01

    Carboxylic esters and lactones react with alkaline hydroxylamine to yield hydroxamates; these in acidic solution form colored iron(III) complexes. A photometric determination of such esters and lactones is thus permitted and has been extensively applied ( I-6). Hestrin ( 3) utilized this method for the microdetermination of acetylcholine and his procedure is much used for the in vitro study of cholinesterase activity and inhibition (4-6).

  5. Gasometric titration for dimethylaluminum chloride analysis.

    PubMed

    Wang, Lin; Maligres, Peter; Eckenroad, Kyle; Simmons, Bryon

    2016-06-01

    A gasometric titration method was developed to quantitate active alkylaluminum content in dimethylaluminum chloride solution to perform the stoichiometry calculation for the reaction charge. The procedure was reproducible with good precision, and the results showed good correlation with ICP-MS method. The gasometric titration is a simple, inexpensive alternative to analysis via ICP-MS which provides more selective analysis of methylaluminum species without the need for inertion.

  6. Application of flow injection gradient titration based on the standard addition and dilution procedure to the determination of total acidity in vinegars and soft drinks.

    PubMed

    Wójtowicz, Marzena; Kozak, Joanna; Górnacka, Dorota; Koscielniak, Pawel

    2008-12-01

    The proposed approach relies on successive dilution of a solution containing a sample with standard addition and on titration of the solutions obtained until receiving a signal lower than the signal measured for the sample alone. Equations are derived for subsequent dilution factors for the automatic flow injection system applied. The overall calibration strategy including the possibility of prediction of the number of required standard solutions and of positioning the sample signal within the calibration range is presented. The method has been tested on the spectrophotometric determination of hydrochloric acid at two concentration levels (0.193 and 1.21 mol L(-1)) with sodium hydroxide as titrant. The results of accuracy better than |3.9|% (RE) and repeatability better than 1.3% (RSD) were obtained. The method has been applied to the determination of total acidity in vinegars and soft drinks. The average time necessary to analyze one sample is about 10 min. PMID:19075470

  7. A hot-cell titration system

    SciTech Connect

    Klatt, L.N.

    1988-07-01

    Operation of nuclear fuel reprocessing plant requires an analytical support laboratory capable of meeting the process control, product quality, and nuclear safeguard requirements. Because of the radioactivity accompanying many of the samples, the analytical instruments must be selected, modified, or specifically developed for use in hot cells. Titrimetric procedures have been successfully used in hot cells and are generally immune to radiation induced bias. This report describes a titration system designed for operation in a hot-cell environment. The potentiometric titration system has operated successfully for four years in support of nuclear fuel reprocessing research and development activities. Details of the hardware, electronic, and software control and data analysis systems are presented. Interchangeable burets with a capacity of 5, 10, and 25 mL are available; the means of the absolute error in delivered volume for these burets are 0.9, 1.1, and 1.8 ..mu..L, respectively. Results of evaluation studies how that the accuracy and precision of analysis results obtained with the potentiometric system are limited by statistical uncertainties associated with the standard titrant, sample preparation procedure, and the equilibrium constant of the titration reaction and not by titrator performance factors. The system is also capable of performing amperometric titrations. Changing between the potentiometric and amperometric modes of operation involves changing the in-cell transducers, the in-cell electronics, and the titrator control program. 22 refs., 13 figs., 9 tabs.

  8. Titrimetric and photometric methods for determination of hypochlorite in commercial bleaches.

    PubMed

    Jonnalagadda, Sreekanth B; Gengan, Prabhashini

    2010-01-01

    Two methods, simple titration and photometric methods for determination of hypochlorite are developed, based its reaction with hydrogen peroxide and titration of the residual peroxide by acidic permanganate. In the titration method, the residual hydrogen peroxide is estimated by titration with standard permanganate solution to estimate the hypochlorite concentration. The photometric method is devised to measure the concentration of remaining permanganate, after the reaction with residual hydrogen peroxide. It employs 4 ranges of calibration curves to enable the determination of hypochlorite accurately. The new photometric method measures hypochlorite in the range 1.90 x 10(-3) to 1.90 x 10(-2) M, with high accuracy and with low variance. The concentrations of hypochlorite in diverse commercial bleach samples and in seawater which is enriched with hypochlorite were estimated using the proposed method and compared with the arsenite method. The statistical analysis validates the superiority of the proposed method. PMID:20446147

  9. A Unified Titration Formula

    NASA Astrophysics Data System (ADS)

    Glaister, P.

    1999-01-01

    In a number of standard titrations, a volume of a monoprotic base MOH at a specific concentration is added to a volume of a monoprotic acid HA at a specific concentrations. Four different types of titration are possible, depending on whether the acid and base are strong or weak. In a recent article, some of these cases are discussed in detail. However, a single unifying formula covering all four cases has been determined.

  10. A titration procedure of the Junonia coenia densovirus and quantitation of transfection by its cloned genomic DNA in four lepidopteran cell lines.

    PubMed

    Li, Y; Jousset, F X; Giraud, C; Rolling, F; Quiot, J M; Bergoin, M

    1996-03-01

    A sensitive and reproducible tissue culture biossay method was developed based on indirect immunofluorescence to titrate virus suspensions of the Junonia coenia densovirus (JcDNV) and to quantify transfections by its cloned genomic DNA. Four lepidopteran cell lines, the SPC-SL 52 from Spodoptera littoralis, the SPC-PL 40 and the SPC-PL 65 cells derived from Spodoptera litura ovaries and hemocytes, respectively, and the SC-LD 135 from Lymantria dispar were compared for their efficiency to support viral replication. The viral titres expressed as TCID50/ml averaged 10(5) for SPC-SL 52, SPC-PL 40 and SC-LD 135 cells, but were above 10(7) for SPC-PL 65 cells. Even with this most sensitive cell line, the rate of infected cells did not exceed 75% and decreased progressively by serial subcultures. Two transfection protocols were used to compare the sensitivity of the same four cell lines to a recombinant plasmid encompassing an infectious sequence of JcDNV genome. SPC-SL 52 cells were found to be the most sensitive, and the lipofection method resulted in about a 5-fold increase compared to the calcium phosphate precipitation protocol. The rescued virions proved to be infectious and the restriction profiles of their DNA were identical to that of wild type virions.

  11. A PC-based titrator for flow gradient titrations

    PubMed Central

    Fuhrmann, B.

    1993-01-01

    This paper describes a PC (personal computer) based titrator which was developed for gradient flow titrations. Concentration gradients were generated electrolytically or volumetrically in small tubes. Complete titration curves can be recorded on-line and evaluated automatically. The titrator can be used with all liquid flow detectors with low axial dispersion. The titrator was evaluated for the titration of thiosulphate with electrogenerated triiodide and for the titration of ammonia with electrogenerated hypobromite after continuous gas dialytic separation of ammonia from the sample solution. PMID:18924977

  12. Colloid Titration--A Rapid Method for the Determination of Charged Colloid.

    ERIC Educational Resources Information Center

    Ueno, Keihei; Kina, Ken'yu

    1985-01-01

    "Colloid titration" is a volumetric method for determining charged polyelectrolytes in aqueous solutions. The principle of colloid titration, reagents used in the procedure, methods of endpoint detection, preparation of reagent solutions, general procedure used, results obtained, and pH profile of colloid titration are considered. (JN)

  13. Simple sensor for potentiometric titrations

    SciTech Connect

    Selig, W.

    1982-01-01

    A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctylphthalate in tetrahydrofuran. The reference was an Ag/AgCl single-junction electrode. The sensor was used in the following potentiometric titrations: (1) precipitation titrations, (2) acid-base titrations, (3) compleximetric titrations, and (4) redox titrations. A survey of its use in such titrations is presented. Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane. 5 figures, 4 tables.

  14. On the accuracy of acid-base determinations from potentiometric titrations using only a few points from the titration curve.

    PubMed

    Olin, A; Wallén, B

    1977-05-01

    There are several procedures which use only a few points on the titration curve for the calculation of equivalence volumes in acid-base titrations. The accuracy of such determinations will depend on the positions of the points on the titration curve. The effects of errors in the stability constants and in the pH measurements on the accuracy of the analysis have been considered, and the results are used to establish the conditions under which these errors are minimized.

  15. Universal tracer monitored titrations.

    PubMed

    DeGrandpre, Michael D; Martz, Todd R; Hart, Robert D; Elison, David M; Zhang, Alice; Bahnson, Anna G

    2011-12-15

    Titrations, while primarily known as the chemical rite of passage for fledgling science students, are still widely used for chemical analysis. With its many years of existence and improvement, the method would seem an unlikely candidate for innovation, yet it is desirable, in this age of autonomous sensing where analyzers may be sent into space or to the bottom of the ocean, to have a simplified titrimetric method that does not rely upon volumetric or gravimetric measurement of sample and titrant. In previous work on the measurement of seawater alkalinity, we found that use of a tracer in the titrant eliminates the need to measure mass or volume. Here, we show the versatility of the method for diverse types of titrations and tracers. The results suggest that tracers may be employed in all types of titrations, opening the door for greatly simplified laboratory and field-based chemical analysis.

  16. pH Static Titration: A Quasistatic Approach

    ERIC Educational Resources Information Center

    Michalowski, Tadeusz; Toporek, Marcin; Rymanowski, Maciej

    2007-01-01

    The pH-static titration is applicable to those systems where at least two types of reactions occur in comparable intensities. The commonalities in titrimetric procedure realized according to pH-static titration, irrespective of the kind of chemical processes occurring are discussed.

  17. Spectrophotometric Titration of a Mixture of Calcium and Magnesium.

    ERIC Educational Resources Information Center

    Fulton, Robert; And Others

    1986-01-01

    Describes a spectrophotometric titration experiment which uses a manual titration spectrophotometer and manually operated buret, rather than special instrumentation. Identifies the equipment, materials, and procedures needed for the completion of the experiment. Recommends the use of this experiment in introductory quantitative analysis…

  18. Acid Rain Analysis by Standard Addition Titration.

    ERIC Educational Resources Information Center

    Ophardt, Charles E.

    1985-01-01

    The standard addition titration is a precise and rapid method for the determination of the acidity in rain or snow samples. The method requires use of a standard buret, a pH meter, and Gran's plot to determine the equivalence point. Experimental procedures used and typical results obtained are presented. (JN)

  19. The Titration Project.

    ERIC Educational Resources Information Center

    Kilner, Cary

    1988-01-01

    Discusses the development of concentration and organizational skills, patience, self-discipline, attention to detail, and appreciation for error analysis through an expanded titration project. Describes the various activities in the extended project and the materials and instructional support needed. Stresses the advantage to students in their…

  20. Filtrates & Residues: Olfactory Titration.

    ERIC Educational Resources Information Center

    Wood, John T.; Eddy, Roberta M.

    1996-01-01

    Presents an experiment that uses a unique acid-base indicator--the odor of raw onion--to indicate the end point of the titration of sodium hydroxide with hydrochloric acid. Allows the student to detect the completion of the neutralization reaction by olfaction rather than sight. (JRH)

  1. Titration Curves: Fact and Fiction.

    ERIC Educational Resources Information Center

    Chamberlain, John

    1997-01-01

    Discusses ways in which datalogging equipment can enable titration curves to be measured accurately and how computing power can be used to predict the shape of curves. Highlights include sources of error, use of spreadsheets to generate titration curves, titration of a weak acid with a strong alkali, dibasic acids, weak acid and weak base, and…

  2. Ion-selective electrodes in potentiometric titrations; a new method for processing and evaluating titration data.

    PubMed

    Granholm, Kim; Sokalski, Tomasz; Lewenstam, Andrzej; Ivaska, Ari

    2015-08-12

    A new method to convert the potential of an ion-selective electrode to concentration or activity in potentiometric titration is proposed. The advantage of this method is that the electrode standard potential and the slope of the calibration curve do not have to be known. Instead two activities on the titration curve have to be estimated e.g. the starting activity before the titration begins and the activity at the end of the titration in the presence of large excess of titrant. This new method is beneficial when the analyte is in a complexed matrix or in a harsh environment which affects the properties of the electrode and the traditional calibration procedure with standard solutions cannot be used. The new method was implemented both in a method of linearization based on the Grans's plot and in determination of the stability constant of a complex and the concentration of the complexing ligand in the sample. The new method gave accurate results when using titrations data from experiments with samples of known composition and with real industrial harsh black liquor sample. A complexometric titration model was also developed.

  3. Microculture virus titration--a simple colourimetric assay for influenza virus titration.

    PubMed

    Levi, R; Beeor-Tzahar, T; Arnon, R

    1995-03-01

    Influenza antigens can be detected by several well established methods. However, when it is important to determine the titre of infective virions, a bioassay should be employed. The standard and the most widely used tests for influenza infectivity are titration carried out in embryonated hen eggs, or the plaque assay employing tissue culture techniques. A simple colourimetric assay for influenza virus detection and titration is described. Samples of allantoic fluid or mice lung homogenates were used to infect MDCK cultures in microplate wells. After an incubation period, the tetrazolium (MTT) colourimetric assay was used to determine cell viability, and when compared to untreated culture control enabled the detection and titration of several influenza strains. When samples were assayed simultaneously in embryonated eggs and by the MCVT method, good correlation in determined titres was obtained. The availability of an additional method for influenza titration allows more flexibility in the choice of titration method according to the specific needs of the study. Furthermore, this method lends itself to full automatization. Similar procedures should also be applicable to titration of other cytopathic viruses.

  4. Colour changes of chemical indicators-VI: metallochromic indicators for direct chelometric titrations of zinc.

    PubMed

    Vytras, K; Vytrasová, J; Kotrlý, S

    1975-06-01

    Eriochrome Blue SE, Eriochrome Red B, Naphthylazoxine 6S, SNAZOXS, and Zincon have been studied in order to find optimum conditions for their use as metallochromic indicators in direct visual chelometric titrations of zinc. The sharpness of the indicator transitions has been investigated by means of photometric titrations and the colour quality has been specified with the aid of the C.I.E. chromaticity systems. Zincon and Eriochrome Blue SE have been found to be the most convenient for visual titrations of zinc.

  5. Photometric Lunar Surface Reconstruction

    NASA Technical Reports Server (NTRS)

    Nefian, Ara V.; Alexandrov, Oleg; Morattlo, Zachary; Kim, Taemin; Beyer, Ross A.

    2013-01-01

    Accurate photometric reconstruction of the Lunar surface is important in the context of upcoming NASA robotic missions to the Moon and in giving a more accurate understanding of the Lunar soil composition. This paper describes a novel approach for joint estimation of Lunar albedo, camera exposure time, and photometric parameters that utilizes an accurate Lunar-Lambertian reflectance model and previously derived Lunar topography of the area visualized during the Apollo missions. The method introduced here is used in creating the largest Lunar albedo map (16% of the Lunar surface) at the resolution of 10 meters/pixel.

  6. Quantitative determination of wine highly volatile sulfur compounds by using automated headspace solid-phase microextraction and gas chromatography-pulsed flame photometric detection. Critical study and optimization of a new procedure.

    PubMed

    López, Ricardo; Lapeña, Ana Cristina; Cacho, Juan; Ferreira, Vicente

    2007-03-01

    The quantitative determination of wine volatile sulfur compounds by automated headspace solid-phase microextraction (HS-SPME) with a carboxen-polydimethylsiloxane (CAR-PDMS) fiber and subsequent gas chromatography-pulsed flame photometric detection (GC-PFPD) has been evaluated. The direct extraction of the sulfur compounds in 5 ml of wine has been found to suffer from matrix effects and short linear ranges, problems which could not be solved by the use of different internal standards or by multiple headspace SPME. These problems were attributed to saturation of the fiber and to competitive effects between analytes, internal standards and other wine volatiles. Another problem was the oxidation of analytes during the procedure. The reduction in sample volume by a factor 50 (0.1 ml diluted with water or brine) brought about a reduction in the amount of sulfur compounds taken in the fiber by a factor just 3.3. Consequently, a new procedure has been proposed. In a sealed vial containing 4.9 ml of saturated NaCl brine, the air is thoroughly displaced with nitrogen, and the wine (0.1 ml) and the internal standards (0.02 ml) are further introduced with a syringe through the vial septum. This sample is extracted at 35 degrees C for 20 min. This procedure makes a satisfactory determination possible of hydrogen sulfide, methanethiol, ethanethiol, dimethyl sulfide, diethyl sulfide and dimethyl disulfide. The linear dynamic ranges cover the normal ranges of occurrence of these analytes in wine with typical r2 between 0.9823 and 0.9980. Reproducibility in real samples ranges from 10 to 20% and repeatability is better than 10% in most cases. The method accuracy is satisfactory, with errors below 20% for hydrogen sulfide and mostly below 10% for the other compounds. The proposed method has been applied to the analysis of 34 Spanish wines.

  7. Radiometric acid-base titrations.

    PubMed

    Erdey, L; Gimesi, O; Szabadváry, F

    1969-03-01

    Acid-base titrations can be performed with radiometric end-point detection by use of labelled metal salts (e.g., ZnCl(2), HgCl(2)). Owing to the formation or dissolution of the corresponding hydroxide after the equivalence point, the activity of the titrated solution linearly increases or decreases as excess of standard solution is added. The end-point of the titration is determined graphically.

  8. A comparison of computer methods for seawater alkalinity titrations

    NASA Astrophysics Data System (ADS)

    Barron, J. L.; Dyrssen, D.; Jones, E. P.; Wedborg, M.

    1983-04-01

    Potentiometric hydrochloric acid titration of seawater provides a powerful technique for determining components of the carbonate system. Recently, questions have been raised regarding older computer procedures for extracting the carbonate system parameters from the titration curve. We compare four evaluation methods, an early Gran method, the GEOSECS Gran method, a new modified Gran method, and a curve-fitting method. We conclude that the new modified Gran method and the curve-fitting can result in a precision of better than 0.1% but because of possible problems associated with representing all relevant chemical reactions during titration, an alkalinity standard must be established before accuracies of 0.1% can be achieved.

  9. Standard Asteroid Photometric Catalogue

    NASA Astrophysics Data System (ADS)

    Piironen, J.; Lagerkvist, C.-I.; Torppa, J.; Kaasalainen, M.; Warner, B.

    2001-12-01

    The Asteroid Photometric Catalogue (APC) is now in its fifth update with over 8600 lightcurves of more than 1000 asteroids in the database. The APC also has references of over one thousand lightcurves not in digital format. The catalogue has been published by Uppsala University Observatory and is distributed by request (contact: classe@astro.uu.se). The new update also includes a list of known asteroid rotational periods and a CD-ROM containing all the existing digital data in the APC. The total number of observed lightcurves is growing rapidly, not the least because of the new state-of-the-art equipment and growing interest among amateur astronomers. The photometric database is now so large that the present format must be altered to facilitate a user-friendly on-line service for the down- and uploading of data. We are proposing (and have started to construct) a new Internet-based Standard Asteroid Photometric Catalogue (SAPC). The website is planned to open during the first half of the year 2002. In addition to the data files, the site would contain the index and guide to the catalogue, a web-form for reporting observations, and some general observing guidelines (e.g., on filters, timing, etc.). There would also be a list of asteroids for which more observations are needed, together with recommended observing periods. This would be accompanied by an up-to-date collection of physical asteroid models based on photometric data, as well as links to observer network pages and other sites that work in collaboration with the catalogue project. Our aim is to develop this site into a global standard service used by everyone involved in asteroid photometry.

  10. A CRITICAL ASSESSMENT OF PHOTOMETRIC REDSHIFT METHODS: A CANDELS INVESTIGATION

    SciTech Connect

    Dahlen, Tomas; Ferguson, Henry C.; Mobasher, Bahram; Faber, Sandra M.; Barro, Guillermo; Guo, Yicheng; Finlator, Kristian; Fontana, Adriano; Gruetzbauch, Ruth; Johnson, Seth; Pforr, Janine; Dickinson, Mark E.; Salvato, Mara; Wuyts, Stijn; Wiklind, Tommy; Acquaviva, Viviana; Huang, Jiasheng; Huang, Kuang-Han; Newman, Jeffrey A.; and others

    2013-10-01

    We present results from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) photometric redshift methods investigation. In this investigation, the results from 11 participants, each using a different combination of photometric redshift code, template spectral energy distributions (SEDs), and priors, are used to examine the properties of photometric redshifts applied to deep fields with broadband multi-wavelength coverage. The photometry used includes U-band through mid-infrared filters and was derived using the TFIT method. Comparing the results, we find that there is no particular code or set of template SEDs that results in significantly better photometric redshifts compared to others. However, we find that codes producing the lowest scatter and outlier fraction utilize a training sample to optimize photometric redshifts by adding zero-point offsets, template adjusting, or adding extra smoothing errors. These results therefore stress the importance of the training procedure. We find a strong dependence of the photometric redshift accuracy on the signal-to-noise ratio of the photometry. On the other hand, we find a weak dependence of the photometric redshift scatter with redshift and galaxy color. We find that most photometric redshift codes quote redshift errors (e.g., 68% confidence intervals) that are too small compared to that expected from the spectroscopic control sample. We find that all codes show a statistically significant bias in the photometric redshifts. However, the bias is in all cases smaller than the scatter; the latter therefore dominates the errors. Finally, we find that combining results from multiple codes significantly decreases the photometric redshift scatter and outlier fraction. We discuss different ways of combining data to produce accurate photometric redshifts and error estimates.

  11. Effects of Acute and Chronic Cocaine Administration on Titrating-Delay Matching-to-Sample Performance

    ERIC Educational Resources Information Center

    Kangas, Brian D.; Branch, Marc N.

    2012-01-01

    The effects of cocaine were examined under a titrating-delay matching-to-sample procedure. In this procedure, the delay between sample stimulus offset and comparison stimuli onset adjusts as a function of the subject's performance. Specifically, matches increase the delay and mismatches decrease the delay. Titrated delay values served as the…

  12. Photometric properties of Mars soils analogs

    USGS Publications Warehouse

    Pommerol, A.; Thomas, N.; Jost, B.; Beck, P.; Okubo, C.; McEwen, A.S.

    2013-01-01

    We have measured the bidirectional reflectance of analogs of dry, wet, and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples to investigate the effects of surface texture. Comparisons with results independently obtained by different teams with similar samples showed a satisfying reproducibility of the photometric measurements as well as a noticeable influence of surface textures resulting from different sample preparation procedures. In a second step, water was introduced to produce wet and frozen samples and their photometry investigated. Optical microscope images of the samples provided information about their microtexture. Liquid water, even in relatively low amount, resulted in the disappearance of the backscattering peak and the appearance of a forward-scattering peak whose intensity increases with the amount of water. Specular reflections only appeared when water was present in an amount large enough to allow water to form a film at the surface of the sample. Icy samples showed a wide variability of photometric properties depending on the physical properties of the water ice. We discuss the implications of these measurements in terms of the expected photometric behavior of the Martian surface, from equatorial to circum-polar regions. In particular, we propose some simple photometric criteria to improve the identification of wet and/or icy soils from multiple observations under different geometries.

  13. Iodine losses during Winkler titrations

    NASA Astrophysics Data System (ADS)

    Knapp, George P.; Stalcup, Marvel C.; Stanley, Robert J.

    1991-01-01

    An experiment designed to measure iodine loss during the aliquot version of the Winkler titration for dissolved oxygen in seawater shows that 0.01-0.03 ml l -1 equivalent oxygen is lost at typical oceanic concentrations in the method presently used. A standardization technique, which mimics that employed during the titration of seawater samples, compensates for this iodine loss throughout the oceanic range. This result, contradicting an earlier report by GREEN and CARRITT (1966, Analyst, 91, 207-208), demonstrates that the whole-bottle method of oxygen titration is not to be preferred over the aliquot method.

  14. Supernova Photometric Lightcurve Classification

    NASA Astrophysics Data System (ADS)

    Zaidi, Tayeb; Narayan, Gautham

    2016-01-01

    This is a preliminary report on photometric supernova classification. We first explore the properties of supernova light curves, and attempt to restructure the unevenly sampled and sparse data from assorted datasets to allow for processing and classification. The data was primarily drawn from the Dark Energy Survey (DES) simulated data, created for the Supernova Photometric Classification Challenge. This poster shows a method for producing a non-parametric representation of the light curve data, and applying a Random Forest classifier algorithm to distinguish between supernovae types. We examine the impact of Principal Component Analysis to reduce the dimensionality of the dataset, for future classification work. The classification code will be used in a stage of the ANTARES pipeline, created for use on the Large Synoptic Survey Telescope alert data and other wide-field surveys. The final figure-of-merit for the DES data in the r band was 60% for binary classification (Type I vs II).Zaidi was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829).

  15. Kinetics of inhibition of influenza virus hemagglutination by homologous antihemagglutinin and antineuraminidase antibodies as measured by means of the photometric antibody concentration unit method.

    PubMed

    Drescher, J; Desselberger, U; Lubach, D

    1974-12-01

    The kinetics of the reactions of antihemagglutinin (AH) and antineuraminidase (AN) antibodies with homologous influenza virus were examined by use of a photometric hemagglutination inhibition test (antibody concentration unit [ACU] test). The following results were obtained. (i) The isotherms describing the reaction of AN antibodies with homologous virus were found to have much steeper slopes than did the corresponding AH antibody isotherm. This finding indicates that the photometric ACU method can discriminate objectively between AH and AN antibodies. (ii) The reaction of mixtures of AH and AN antibodies with homologous virus was examined and found that AH antibodies combine with virus independently from the presence of AN antibodies, whereas AH antibodies were found to reduce greatly the measurable degree of hemagglutination inhibition by AN antibodies. (iii) A formula was developed and experimentally confirmed by means of which the binding of virus by mixtures of AH and AN antibodies can be predicted. Thereby, the influence of the relative concentration of AH and AN antibodies on the establishing of isotherms and on their subsequent use for antibody titration by means of the photometric ACU method was investigated. It was found that the procedure routinely employed for establishing isotherms yielded data reflecting the reaction of AH antibodies only. As a consequence, the use of these isotherms will identify AH antibodies.

  16. Amperometric, Bipotentiometric, and Coulometric Titration.

    ERIC Educational Resources Information Center

    Stock, John T.

    1980-01-01

    Discusses recent review articles in various kinds of titration. Also discusses new research in apparatus and methodology, acid-base reactions, precipitation and complexing reactions, oxidation-reduction reactions, and nomenclature. Cites 338 references. (CS)

  17. Asphalt compatibility testing using the automated Heithaus titration test

    SciTech Connect

    Pauli, A.T.

    1996-12-31

    The Heithaus titration test or variations of the test have been used for over 35 years to predict compatibilities of blends of asphalts from different crude sources. Asphalt compatibility is determined from three calculated parameters that measure the state of peptization of an asphalt or asphalt blend. The parameter p{sub a} is a measure of the peptizability of the asphaltenes. The parameter p{sub a} is a measure of the peptizing power of the maltenes, and the parameter P, derived from p{sub a} and p{sub o} values, is a measure of the overall state of peptization of the asphalt or asphalt blend. In Heithaus original procedure, samples of asphalt were dissolved in toluene and titrated with n-heptane in order to initiate flocculation. The onset of flocculation was detected either by photography or by spotting a filter paper with a small amount of the titrated solution. Recently, an {open_quotes}automated{close_quotes} procedure, after Hotier and Robin, has been developed for use with asphalt. In the automated method UV-visible spectrophotometric detection measures the onset of flocculation as a peak with the percent transmittance plotted as a function of the volume of titrating solvent added to a solution of asphalt. The automated procedure has proven to be less operator dependent and much faster than the original Heithaus procedure. Results from the automated procedure show the data to be consistent with results from the original, {open_quotes}classical{close_quotes} Heithaus procedure.

  18. Potentiometric/turbidometric titration of antiperspirant actives.

    PubMed

    Johnston, Clifford T; Hem, Stanley L; Guenin, Eric; Mattai, Jairajh; Afflito, John

    2003-01-01

    A titration procedure that simultaneously monitors the pH and turbidity of an antiperspirant solution during neutralization with sodium hydroxide was developed to characterize antiperspirant actives. Aluminum chloride, aluminum chlorohydrate (ACH), and aluminum zirconium glycine complex (AZG) gave distinctive pH/turbidity profiles. The activated forms of aluminum chlorohydrate (ACH') and aluminum zirconium glycine complex (AZG') produced more turbidity than the non-activated forms. On an equimolar basis, AZG' produced more turbidity than any of the antiperspirant actives tested. PMID:12715089

  19. High concentration aqueous sodium fluoride certified reference materials for forensic use certified by complexometric titration.

    PubMed

    Archer, Marcellé; Brits, Martin; Prevoo-Franzsen, Désirée; Quinn, Laura

    2015-04-01

    Sodium fluoride in concentrations of 1 to 2 % is used to prevent the formation of ethanol in blood and urine samples that are to be analysed for ethanol content. The majority of such samples form part of forensic investigations into alleged drunken driving. In South Africa, the laboratory performing the tests is required to prove that the sodium fluoride concentration in the blood samples is above 1 g/100 ml on receipt. This is done by using a fluoride ion-selective electrode calibrated with external aqueous solutions of sodium fluoride. The National Metrology Institute of South Africa (NMISA) prepares sodium fluoride solutions in concentrations from 0.3 to 3.0 g/100 ml. No other certified sodium fluoride reference solutions in these concentrations are available commercially. The sodium fluoride is certified by precipitation of the fluoride as lead chlorofluoride (PbClF) through the addition of a known excess of lead nitrate. The excess lead is back-titrated with ethylenediamine tetraacetic acid (EDTA) using a photometric electrode to detect the endpoint. Aqueous sodium fluoride solutions are prepared and the concentrations verified by the precipitation/back-titration method. This paper shows the application of a classical complexometric method to the certification of reference materials and describes the procedures for the preparation of the sodium fluoride solutions, verification of the concentrations, homogeneity and stability by primary titrimetry. It also briefly covers the calculation of uncertainty, the establishment of traceability and the quality control measures applied to ensure the quality of the certified reference materials (CRMs). PMID:25326884

  20. High concentration aqueous sodium fluoride certified reference materials for forensic use certified by complexometric titration.

    PubMed

    Archer, Marcellé; Brits, Martin; Prevoo-Franzsen, Désirée; Quinn, Laura

    2015-04-01

    Sodium fluoride in concentrations of 1 to 2 % is used to prevent the formation of ethanol in blood and urine samples that are to be analysed for ethanol content. The majority of such samples form part of forensic investigations into alleged drunken driving. In South Africa, the laboratory performing the tests is required to prove that the sodium fluoride concentration in the blood samples is above 1 g/100 ml on receipt. This is done by using a fluoride ion-selective electrode calibrated with external aqueous solutions of sodium fluoride. The National Metrology Institute of South Africa (NMISA) prepares sodium fluoride solutions in concentrations from 0.3 to 3.0 g/100 ml. No other certified sodium fluoride reference solutions in these concentrations are available commercially. The sodium fluoride is certified by precipitation of the fluoride as lead chlorofluoride (PbClF) through the addition of a known excess of lead nitrate. The excess lead is back-titrated with ethylenediamine tetraacetic acid (EDTA) using a photometric electrode to detect the endpoint. Aqueous sodium fluoride solutions are prepared and the concentrations verified by the precipitation/back-titration method. This paper shows the application of a classical complexometric method to the certification of reference materials and describes the procedures for the preparation of the sodium fluoride solutions, verification of the concentrations, homogeneity and stability by primary titrimetry. It also briefly covers the calculation of uncertainty, the establishment of traceability and the quality control measures applied to ensure the quality of the certified reference materials (CRMs).

  1. Acid-base and chelatometric photo-titrations with photosensors and membrane photosensors.

    PubMed

    Matsuo, T; Masuda, Y; Sekido, E

    1986-08-01

    Photosensors (PS) and membrane photosensors (MPS), which can be immersed in the test solution and facilitate the measurement of concentration, have been developed by miniaturizing an optical system consisting of a light source and a photocell. For use in acid-base or complexometric titrations a poly(vinyl chloride) membrane containing an acid-base or metallochromic indicator can be applied as a coating to the photocell. Spectrophotometric determination of copper(II), and photometric acid-base and chelatometric titrations have been performed with the PS and MPS systems.

  2. Determination of sulphite in wine by coulometric titration.

    PubMed

    Lowinsohn, D; Bertotti, M

    2001-09-01

    A method for the determination of both free and bound S(IV) in white wine samples by coulometric titration with electrogenerated iodine is described, the S(IV) speciation being performed by extracting SO2 from samples acidified wiith hydrochloric acid. Titrations of samples treated with NaOH led to the total S(IV) concentration, the results being in agreement with the ones obtained by the distillation procedure as well as by using the classical Monier-Williams method. An average recovery of 97% was obtained for samples spiked with S(IV) in the range 0.4-1.2 mM, which demonstrated the validity of the proposed procedure. The repeatability was 1.3% and the limit of detection was estimated as 0.01 mM. Results from direct titrations of wine added to the electrochemical cell are reported, which give indications of the stability of adducts towards the reaction with iodine.

  3. Assembling and Using an LED-Based Detector to Monitor Absorbance Changes during Acid-Base Titrations

    ERIC Educational Resources Information Center

    Santos, Willy G.; Cavalheiro, E´der T. G.

    2015-01-01

    A simple photometric assembly based in an LED as a light source and a photodiode as a detector is proposed in order to follow the absorbance changes as a function of the titrant volume added during the course of acid-base titrations in the presence of a suitable visual indicator. The simplicity and low cost of the electronic device allow the…

  4. 40 CFR Appendix A to Part 425 - Potassium Ferricyanide Titration Method

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... concentrations determined by EPA test procedure 376.1 (see 40 CFR 136.3, Table IB, parameter 66 (49 FR 43234... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Potassium Ferricyanide Titration... Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The potassium ferricyanide...

  5. 40 CFR Appendix A to Part 425 - Potassium Ferricyanide Titration Method

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... concentrations determined by EPA test procedure 376.1 (see 40 CFR 136.3, Table IB, parameter 66 (49 FR 43234... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Potassium Ferricyanide Titration..., App. A Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The...

  6. 40 CFR Appendix A to Part 425 - Potassium Ferricyanide Titration Method

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... concentrations determined by EPA test procedure 376.1 (see 40 CFR 136.3, Table IB, parameter 66 (49 FR 43234... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Potassium Ferricyanide Titration..., App. A Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The...

  7. 40 CFR Appendix A to Part 425 - Potassium Ferricyanide Titration Method

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... concentrations determined by EPA test procedure 376.1 (see 40 CFR 136.3, Table IB, parameter 66 (49 FR 43234... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Potassium Ferricyanide Titration..., App. A Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The...

  8. 40 CFR Appendix A to Part 425 - Potassium Ferricyanide Titration Method

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... concentrations determined by EPA test procedure 376.1 (see 40 CFR 136.3, Table IB, parameter 66 (49 FR 43234... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Potassium Ferricyanide Titration... Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The potassium ferricyanide...

  9. Determination of Acidity Constants by Gradient Flow-Injection Titration

    ERIC Educational Resources Information Center

    Conceicao, Antonio C. L.; Minas da Piedade, Manuel E.

    2006-01-01

    A three-hour laboratory experiment, designed for an advanced undergraduate course in instrumental analysis that illustrates the application of the gradient chamber flow-injection titration (GCFIT) method with spectrophotometric detection to determine acidity constants is presented. The procedure involves the use of an acid-base indicator to obtain…

  10. Photometric stereo endoscopy

    PubMed Central

    Parot, Vicente; Lim, Daryl; González, Germán; Traverso, Giovanni; Nishioka, Norman S.; Vakoc, Benjamin J.

    2013-01-01

    Abstract. While color video endoscopy has enabled wide-field examination of the gastrointestinal tract, it often misses or incorrectly classifies lesions. Many of these missed lesions exhibit characteristic three-dimensional surface topographies. An endoscopic system that adds topographical measurements to conventional color imagery could therefore increase lesion detection and improve classification accuracy. We introduce photometric stereo endoscopy (PSE), a technique which allows high spatial frequency components of surface topography to be acquired simultaneously with conventional two-dimensional color imagery. We implement this technique in an endoscopic form factor and demonstrate that it can acquire the topography of small features with complex geometries and heterogeneous optical properties. PSE imaging of ex vivo human gastrointestinal tissue shows that surface topography measurements enable differentiation of abnormal shapes from surrounding normal tissue. Together, these results confirm that the topographical measurements can be obtained with relatively simple hardware in an endoscopic form factor, and suggest the potential of PSE to improve lesion detection and classification in gastrointestinal imaging. PMID:23864015

  11. Amperometric, Bipotentiometric, and Coulometric Titration.

    ERIC Educational Resources Information Center

    Stock, John T.

    1984-01-01

    Reviews literature on amperometric, bipotentiometric, and coulometric titration methods examining: apparatus and methodology; acid-base reactions; precipitation and complexing reactions (considering methods involving silver, mercury, EDTA or analogous reagents, and other organic compounds); and oxidation-reduction reactions (considering methods…

  12. Evaluation of the 5 and 8 pH point titration methods for monitoring anaerobic digesters treating solid waste.

    PubMed

    Vannecke, T P W; Lampens, D R A; Ekama, G A; Volcke, E I P

    2015-01-01

    Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness.

  13. Determination of Poly(Diallyldimethylammonium Chloride) via Spectrophotometric Titration with Coomassie Brilliant Blue G Dye.

    PubMed

    Shyichuk, Alexander; Ziółkowska, Dorota; Lamkiewicz, Jan

    2016-02-01

    Poly(diallyldimethylammonium chloride) (PDDA) is used as organic coagulant in water purification and auxiliary agent in paper production. Determination of PDDA in aqueous solutions is carried out usually by means of polyelectrolyte titration using streaming current detector or o-Toluidine Blue dye for endpoint recognition. The proposed method of PDDA assay takes advantage of Coomassie Brilliant Blue G dye having strong affinity to cationic macromolecules. Titration of PDDA solution with the dye is carried out measuring absorbance at 585 nm. Inflection points of the obtained zigzag photometric curves have good repeatability provided that titration rate is low enough to attain endpoint for 1 hour or more. The method assures rectilinear calibration (R² = 0.999 5) in the broad range of PDDA concentrations from 0.3 to 9.6 mg · dm⁻³.

  14. Complexometric titrations: new reagents and concepts to overcome old limitations.

    PubMed

    Zhai, Jingying; Bakker, Eric

    2016-07-21

    Chelators and end point indicators are the most important parts of complexometric titrations. The most widely used universal chelator ethylenediamine tetraacetic acid (EDTA) and its derivatives can strongly coordinate with different metal ions. Their limited selectivity often requires the use of masking agents, and the multiple pKa values of the chelators necessitate a careful adjustment of pH during the procedure. Real world requirements for pH independent, selective and sensitive chelators and indicators call for a new design of these reagents. New concepts and structures of chelators and indicators have indeed recently emerged. We present here recent developments on chelators and indicators for complexometric titrations. Many of these advances were made possible only recently by moving the titration from a homogeneous to a heterogeneous phase using a new class of chelators and indicators based on highly selective ionophores embedded in ion-selective nanosphere emulsions. In view of achieving titrations in situ by complete instrumental control, thin layer electrochemistry has recently been shown to be an attractive concept that replaces the traditional cumbersome titration protocol with a direct reagent free sensing tool. PMID:27272695

  15. Surface characterization of hydroxyapatite: potentiometric titrations coupled with solubility measurements.

    PubMed

    Skartsila, Kyriaki; Spanos, Nikos

    2007-04-15

    The acid-base properties of synthetically prepared and well-characterized hydroxyapatite (HAP) in contact with KNO3 solutions were investigated at 25 degrees C, through potentiometric titrations, zeta-potential measurements, and surface complex modeling. Aliquots of suspension were withdrawn every 0.5 pH unit during the titration procedure and analyzed for calcium and phosphate. It was found that, even for rapid titration experiments, a remarkable amount of H+ ions (H+dissol.) is consumed in the bulk solution in reacting with species coming from the dissolution of HAP. These H+ ions must be taken into account in the H+ mass balance, in order for true value for the point of zero charge (pzc=6.5+/-0.2) and consequently true value for the surface charge (sigma0) to be obtained. Besides the conventional potentiometric titration technique, it was found that pzc may be determined much more easily as the intersection point of the suspension titration curve and the blank one modified to include the amount of H+dissol. obtained at one ionic strength. Finally, a surface complexation model was proposed for the development of surface charge. Experimental data were satisfactorily fitted by using the value of 4.2 F m-2 for the capacitance.

  16. Complexometric titrations: new reagents and concepts to overcome old limitations.

    PubMed

    Zhai, Jingying; Bakker, Eric

    2016-07-21

    Chelators and end point indicators are the most important parts of complexometric titrations. The most widely used universal chelator ethylenediamine tetraacetic acid (EDTA) and its derivatives can strongly coordinate with different metal ions. Their limited selectivity often requires the use of masking agents, and the multiple pKa values of the chelators necessitate a careful adjustment of pH during the procedure. Real world requirements for pH independent, selective and sensitive chelators and indicators call for a new design of these reagents. New concepts and structures of chelators and indicators have indeed recently emerged. We present here recent developments on chelators and indicators for complexometric titrations. Many of these advances were made possible only recently by moving the titration from a homogeneous to a heterogeneous phase using a new class of chelators and indicators based on highly selective ionophores embedded in ion-selective nanosphere emulsions. In view of achieving titrations in situ by complete instrumental control, thin layer electrochemistry has recently been shown to be an attractive concept that replaces the traditional cumbersome titration protocol with a direct reagent free sensing tool.

  17. A photometric study of the Orion OB 1 association. I - Observational data. II - Photometric analysis

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.; Hesser, J. E.

    1977-01-01

    A catalog of observational data is presented for stars in the region of the young stellar association Orion OB 1. Photoelectric observations obtained in the uvby-beta and UBV systems are compiled along with previous photoelectric and spectroscopic data for all these stars as well as for several bright members of the association with available photometric indices. Mean weighted values are computed for the photometric data and summarized in tables expected to be reasonably complete for association members earlier than spectral type A0. Membership criteria are derived, and qualitative membership probabilities summarized, for the 526 stars in the final program. The analytical procedures are discussed for association stars of B, intermediate, and AF types. Effects of the nebular environment and various calibrations of Balmer-line and four-color indices are considered for the determination of absolute magnitudes for the B-type stars.

  18. Titration of adenovirus by counting cells containing virus-induced inclusion bodies.

    PubMed

    Weber, J

    1972-05-01

    A new method for the titration of adenovirus types 2 and 12 based on the enumeration of viral inclusions in infected cells was devised and evaluated. The technique gave virus titers comparable to those obtained by the plaque assay procedure.

  19. Going Beyond, Going Further: The Preparation of Acid-Base Titration Curves.

    ERIC Educational Resources Information Center

    McClendon, Michael

    1984-01-01

    Background information, list of materials needed, and procedures used are provided for a simple technique for generating mechanically plotted acid-base titration curves. The method is suitable for second-year high school chemistry students. (JN)

  20. Colorblindness and Titrations with Visual Indicators.

    ERIC Educational Resources Information Center

    Diehl, Harvey; And Others

    1985-01-01

    Discusses various issues related to colorblind students performing titrations with visual indicators. Includes tables showing precisions in the titration of a weak acid by colorblind students using phenolphthalein and thymolphthalein and in the titration of a weak base by colorblind persons using methyl red and bromcresol green. (JN)

  1. Killed poliovirus antigen titration in humans.

    PubMed

    Salk, J; Cohen, H; Fillastre, C; Stoeckel, P; Rey, J L; Schlumberger, M; Nicolas, A; van Steenis, G; van Wezel, A L; Triau, R; Saliou, P; Barry, L F; Moreau, J P; Mérieux, C

    1978-01-01

    To establish the antigen content of a killed poliovirus vaccine sufficiently potent to induce immunity with one or two doses and to establish a reference standard vaccine which has been tested under field conditions, a titration was carried out in infants to determine the amount of each of the three antigenic types of poliovirus vaccine required to induce seroconversion with a single dose. It has been observed that over a critical range of antigen concentration there is an essentially linear relationship between antibody response and quantity of antigen administered. More than 90 percent of the groups studied had detectable antibody after receiving single injections of 80, 8 and 64 D-antigen units of Types I, II and III, respectively. Four-fold less antigen for each of the three types was less effective. The implications of these findings for an efficient immunization procedure are discussed.

  2. Rapid method for SV40 titration.

    PubMed

    Drayman, Nir; Kler, Slava; Ben-nun-Shaul, Orly; Oppenheim, Ariella

    2010-03-01

    SV40 titer is determined traditionally by the conventional plaque assay. Plaques appear after several rounds of infection and the assay takes around two weeks, which may delay research. A simpler assay was developed, based on detection of T-antigen in the infected cells by flow cytometry. Cells grown in 6-well plates are infected with serial dilutions of the viral stock, harvested 48h post-infection, stained and analyzed for T-antigen using a flow cytometer. The viral titer is calculated based on the percentage of T-antigen positive cells. The procedure is accomplished in 2 days. Unexpectedly we found that titers on different permissive African Green Monkey kidney cell lines were consistently different, suggesting variable susceptibility to SV40 infection. The method described, optimized for SV40 titration, may be adapted readily to other viruses.

  3. An elevated temperature titration calorimeter

    SciTech Connect

    Smith, J.R.; Zanonato, P.L.; Choppin, G.R. . Dept. of Chemistry)

    1991-06-01

    A variable-temperature (313 K to 353 K) titration calorimeter of high sensitivity has been constructed. The purpose of the calorimeter is to study temperature effects on the enthalpies of complex formation and of other reactions of metal cations such as hydrolysis and precipitation. Operation of the calorimetric system, including that final calculation of the heat released during titration, is automatic via computer control. Calibration tests of the calorimeter using 2-amino-2-hydroxymethyl-1,3-propanediol gave -(46.0 {plus minus} 0.3) kJ mol{sup {minus}1} and -(46.2 {plus minus} 0.2) kJ mol{sup {minus}1} for the enthalpy of protonation, at 318 K and at 343 K, respectively. For titrations of 2-bis(2-hydroxyethyl) amino-2-hydroxymethyl-1,3-propanediol, enthalpy of protonation values of -(28.4 {plus minus} 0.3) kJ mol{sup {minus}1} and -(29.3 {plus minus} 0.2) kJ mol{sup {minus}1} were obtained at 318 K and at 343 K, respectively. 6 refs., 3 figs., 2 tabs.

  4. Improving Photometric Calibration of Meteor Video Camera Systems

    NASA Technical Reports Server (NTRS)

    Ehlert, Steven; Kingery, Aaron; Cooke, William

    2016-01-01

    Current optical observations of meteors are commonly limited by systematic uncertainties in photometric calibration at the level of approximately 0.5 mag or higher. Future improvements to meteor ablation models, luminous efficiency models, or emission spectra will hinge on new camera systems and techniques that significantly reduce calibration uncertainties and can reliably perform absolute photometric measurements of meteors. In this talk we discuss the algorithms and tests that NASA's Meteoroid Environment Office (MEO) has developed to better calibrate photometric measurements for the existing All-Sky and Wide-Field video camera networks as well as for a newly deployed four-camera system for measuring meteor colors in Johnson-Cousins BV RI filters. In particular we will emphasize how the MEO has been able to address two long-standing concerns with the traditional procedure, discussed in more detail below.

  5. Simultaneous determination of equivalence volumes and acid dissociation constants from potentiometric titration data.

    PubMed

    Papanastasiou, G; Ziogas, I

    1995-06-01

    New iterative methods for analysis of potentiometric titration data of (a) mixtures of weak monoprotic acids with their conjugate bases, (b) solutions of polyprotic (di- and triprotic) acids, and (c) mixtures of two diprotic acids are presented. These methods, using data exclusively resulting from the acidic region of the titration curve permits the accurate determination of the analytical concentration of one or more acids even if the titration is stopped well before the end point of the titration. For the titration of a solution containing a conjugate acid/base pair, the proposed procedure enables the extraction of the initial composition of the mixture, as well as the dissociation constant of the concerned acid. Thus, it is possible by this type of analysis to distinguish whether a weak acid has been contaminated by a strong base and define the extent of the contamination. On the other hand, for the titration of polyprotic acids, the proposed approach enables the extraction of the accurate values of the equivalence volume and the dissociation constants K(i) even when the ionization stages overlap. Finally, for the titration of a mixture of two diprotic acids the proposed procedure enables the determination of the composition of the mixture even if the sum of the concentrations of the acids is not known. This method can be used in the analysis of solutions containing two diastereoisomeric forms of a weak diprotic acid. The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable even when the titration data are considerably obscured by 'noise' or contain an important systematic error. The proposed procedures were also successfully applied to experimental titration data.

  6. Risks and Benefits of Rapid Clozapine Titration.

    PubMed

    Lochhead, Jeannie D; Nelson, Michele A; Schneider, Alan L

    2016-05-18

    Clozapine is often considered the gold standard for the treatment of schizophrenia. Clinical guidelines suggest a gradual titration over 2 weeks to reduce the risks of adverse events such as seizures, hypotension, agranulocytosis, and myocarditis. The slow titration often delays time to therapeutic response. This raises the question of whether, in some patients, it may be safe to use a more rapid clozapine titration. The following case illustrates the potential risks associated with the use of multiple antipsychotics and rapid clozapine titration. We present the case of a young man with schizophrenia who developed life threatening neuroleptic malignant syndrome (NMS) during rapid clozapine titration and treatment with multiple antipsychotics. We were unable to find another case in the literature of NMS associated with rapid clozapine titration. This case is meant to urge clinicians to carefully evaluate the risks and benefits of rapid clozapine titration, and to encourage researchers to further evaluate the safety of rapid clozapine titration. Rapid clozapine titration has implications for decreasing health care costs associated with prolonged hospitalizations, and decreasing the emotional suffering associated with uncontrolled symptoms of psychosis. Clozapine is considered the most effective antipsychotic available thus efforts should focus on developing strategies that would allow for safest and most efficient use of clozapine to encourage its utilization for treatment resistance schizophrenia.

  7. An improved photometric analysis of SX Aurigae

    NASA Technical Reports Server (NTRS)

    Linnel, Albert P.; Peters, Geraldine J.; Polidan, Ronald S.

    1988-01-01

    A new analysis of existing photometric data on SX Aurigae is presented which changes current conclusions in the literature concerning the star. It is concluded, based on fitting of the continuous spectrum to Kurucz model atmospheres and simplex optimization procedure utilized, that the system consists of two normal main-sequence stars of spectral types B2 and slightly earlier than B5. The components are very close to the inner Roche limiting surface. The secondary component is unevolved, and the primary component is extremely close to contact with its inner Roche lobe. The evidence indicates that mass flow from the primary to the secondary has not yet begun. Allowing the bolometric albedo of the secondary to be a free parameter produces a solution with an excellent fit to the B, V data. The derived value, A2 = 0.40, disagrees with the theoretical value for radiative atmospheres and agrees with the value for convective equilibrium.

  8. Logarithmic diagrams in acid-base titrations and estimation of titration errors.

    PubMed

    Wänninen, E

    1980-01-01

    The use of a logarithmic diagram for the estimation of the pH-value at the equivalence point and the titration error when a solution containing one or two acids is titrated with standard alkali is described.

  9. Photometric Properties of Solar System Ices

    NASA Astrophysics Data System (ADS)

    Verbiscer, A. J.; Helfenstein, P.; Buratti, B. J.

    We present an overview of fundamental photometric properties of icy surfaces throughout the Solar System and investigate the extent to which these properties reflect the evolution of the bodies on which they reside. We review photometric models and their parameters and discuss the physical interpretability of those parameters. We focus on those fundamental photometric properties, primarily albedo and the near-opposition phase function, which are independent of any interpretation from the application of a photometric model. Finally, we offer suggestions for future work, both observational and laboratory measurements, which will enhance the scientific return from continued photometric studies of icy bodies in the Solar System.

  10. Methods for growing and titrating African swine fever virus: field and laboratory samples.

    PubMed

    Carrascosa, Angel L; Bustos, M Jose; de Leon, Patricia

    2011-12-01

    Growing African swine fever virus (ASFV) isolates obtained mainly from the field, but also engineered in the laboratory, is a critical step for diagnosis, titration, or virus infection studies. This unit describes a set of methods and protocols to produce and titrate any ASFV strain in cell cultures. The procedures include (1) basic techniques to prepare virus-sensitive target cells; (2) strategies for growth, concentration, and purification of virus stocks; and (3) the semi-quantitative (end dilution) and quantitative (plaque) assays for the determination of viral titers, and the use of different ASFV-sensitive cells as targets for virus production and titration.

  11. Acid-base titrations in nonaqueous solvents Analysis of dimethyl sulphate.

    PubMed

    Banick, W M; Francis, E C

    1966-07-01

    A nonaqueous titrimetric procedure was developed for the determination of the dimethyl sulphate, methyl hydrogen sulphate and sulphuric acid content of dimethyl sulphate samples. Methyl hydrogen sulphate and sulphuric acid are determined by a differentiating potentiometric titration in pyridine with tributylethylammonium hydroxide. Pyridine converts the dimethyl sulphate into the weakly acidic methylpyridinium methyl sulphate which does not interfere in the titration. Dimethyl sulphate is determined by reacting it with an excess of 2-dimethylaminoethanol and titrating the excess with perchloric acid. Precision and recovery data for commercial samples of dimethyl sulphate are presented.

  12. Toward Millimagnitude Photometric Calibration (Abstract)

    NASA Astrophysics Data System (ADS)

    Dose, E.

    2014-12-01

    (Abstract only) Asteroid roation, exoplanet transits, and similar measurements will increasingly call for photometric precisions better than about 10 millimagnitudes, often between nights and ideally between distant observers. The present work applies detailed spectral simulations to test popular photometric calibration practices, and to test new extensions of these practices. Using 107 synthetic spectra of stars of diverse colors, detailed atmospheric transmission spectra computed by solar-energy software, realistic spectra of popular astronomy gear, and the option of three sources of noise added at realistic millimagnitude levels, we find that certain adjustments to current calibration practices can help remove small systematic errors, especially for imperfect filters, high airmasses, and possibly passing thin cirrus clouds.

  13. Photometrics at Sandia National Laboratories

    SciTech Connect

    McWilliams, J.Y.; Hill, R.A.; Hughes, R.L.

    1990-07-01

    This report highlights Sandia National Laboratories' work in the following areas: photometrics and optical development; still and time-lapse photography; real-time motion photography; high-speed photography; image-motion photography; schlieren photography; ultra-high-speed photography; electronic imaging; shuttered video and high-speed video; infrared imaging radiometry; exoatmospheric photography and videography; microdensitometry and image analysis; and optical system design and development.

  14. Isothermal titration calorimetry of RNA.

    PubMed

    Salim, Nilshad N; Feig, Andrew L

    2009-03-01

    Isothermal titration calorimetry (ITC) is a fast and robust method to study the physical basis of molecular interactions. A single well-designed experiment can provide complete thermodynamic characterization of a binding reaction, including K(a), DeltaG, DeltaH, DeltaS and reaction stoichiometry (n). Repeating the experiment at different temperatures allows determination of the heat capacity change (DeltaC(P)) of the interaction. Modern calorimeters are sensitive enough to probe even weak biological interactions making ITC a very popular method among biochemists. Although ITC has been applied to protein studies for many years, it is becoming widely applicable in RNA biochemistry as well, especially in studies which involve RNA folding and RNA interactions with small molecules, proteins and with other RNAs. This review focuses on best practices for planning, designing and executing effective ITC experiments when one or more of the reactants is an RNA. PMID:18835447

  15. A Precise Lunar Photometric Function

    NASA Astrophysics Data System (ADS)

    McEwen, A. S.

    1996-03-01

    The Clementine multispectral dataset will enable compositional mapping of the entire lunar surface at a resolution of ~100-200 m, but a highly accurate photometric normalization is needed to achieve challenging scientific objectives such as mapping petrographic or elemental compositions. The goal of this work is to normalize the Clementine data to an accuracy of 1% for the UVVIS images (0.415, 0.75, 0.9, 0.95, and 1.0 micrometers) and 2% for NIR images (1.1, 1.25, 1.5, 2.0, 2.6, and 2.78 micrometers), consistent with radiometric calibration goals. The data will be normalized to R30, the reflectance expected at an incidence angle (i) and phase angle (alpha) of 30 degrees and emission angle (e) of 0 degree, matching the photometric geometry of lunar samples measured at the reflectance laboratory (RELAB) at Brown University The focus here is on the precision of the normalization, not the putative physical significance of the photometric function parameters. The 2% precision achieved is significantly better than the ~10% precision of a previous normalization.

  16. Cosmology with photometric redshift surveys

    NASA Astrophysics Data System (ADS)

    Blake, Chris; Bridle, Sarah

    2005-11-01

    We explore the utility of future photometric redshift imaging surveys for delineating the large-scale structure of the Universe, and assess the resulting constraints on the cosmological model. We perform the following two complementary types of analysis. (i) We quantify the statistical confidence and the accuracy with which such surveys will be able to detect and measure characteristic features in the clustering power spectrum such as the acoustic oscillations and the turnover, in a `model-independent' fashion. We show for example that a 10000-deg2 imaging survey with depth r= 22.5 and photometric redshift accuracy δz/(1 +z) = 0.03 will detect the acoustic oscillations with 99.9 per cent confidence, measuring the associated preferred cosmological scale with 2 per cent precision. Such a survey will also detect the turnover with 95 per cent confidence, determining the corresponding scale with 20 per cent accuracy. (ii) By assuming a Λ cold dark matter (ΛCDM) model power spectrum we calculate the confidence with which a non-zero baryon fraction can be deduced from such future galaxy surveys. We quantify `wiggle detection' by calculating the number of standard deviations by which the baryon fraction is measured, after marginalizing over the shape parameter. This is typically a factor of 4 more significant (in terms of number of standard deviations) than the above `model-independent' result. For both analyses, we quantify the variation of the results with magnitude depth and photometric redshift precision, and discuss the prospects for obtaining the required performance with realistic future surveys. We conclude that the precision with which the clustering pattern may be inferred from future photometric redshift surveys will be competitive with contemporaneous spectroscopic redshift surveys, assuming that systematic effects can be controlled. We find that for equivalent wiggle detection power, a photometric redshift survey requires an area approximately 12[δz/(1 +z

  17. A Tabular Approach to Titration Calculations

    ERIC Educational Resources Information Center

    Lim, Kieran F.

    2012-01-01

    Titrations are common laboratory exercises in high school and university chemistry courses, because they are easy, relatively inexpensive, and they illustrate a number of fundamental chemical principles. While students have little difficulty with calculations involving a single titration step, there is a significant leap in conceptual difficulty…

  18. SBR on-line monitoring by set-point titration.

    PubMed

    Fiocchi, N; Ficara, E; Canziani, R; Luccarini, L; Ciappelloni, F; Ratini, P; Pirani, M; Mariani, S

    2006-01-01

    The applicability of set-point titration for monitoring biological processes has been widely demonstrated in the literature. Based on published and on-going experiences, some operating procedures have been specifically developed to be applied to SBRs, so that real-time information about the process and/or the influent can be obtained. This, in turn, would allow plant operators to select the most appropriate actions properly and timely. Five operating modes are described for the monitoring of (1) influent toxicity, (2) influent N-content, (3) nitrification capacity, (4) end of the nitrification reaction, and (5) nitrate effluent concentration, and are currently tested on the on-line titrator TITAAN (TITrimetric Automated ANalyser) which is in operation on a pilot scale SBR. PMID:16722107

  19. Photometric Characteristics of Lunar Terrains

    NASA Astrophysics Data System (ADS)

    Sato, Hiroyuki; Hapke, Bruce W.; Denevi, Brett W.; Robinson, Mark

    2016-10-01

    The photometric properties of the lunar depend on albedo, surface roughness, porosity, and the internal/external structure of particles. Hapke parameter maps derived using a bidirectional reflectance model [Hapke, 2012] from Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images demonstrated the spatial and spectral variation of the photometric properties of the Moon [Sato et al., 2014]. Using the same methodology, here we present the photometric characteristics of typical lunar terrains, which were not systematically analyzed in the previous study.We selected five representative terrain types: mare, highland, swirls, and two Copernican (fresh) crater ejecta (one mare and one highlands example). As for the datasets, we used ~39 months of WAC repeated observations, and for each image pixel, we computed latitude, longitude, incidence, emission, and phase angles using the WAC GLD100 stereo DTM [Scholten et al., 2012]. To obtain similar phase and incidence angle ranges, all sampling sites are near the equator and in the vicinity of Reiner Gamma. Three free Hapke parameters (single scattering albedo: w, HG2 phase function parameter: c, and angular width of SHOE: hs) were then calculated for the seven bands (321-689 nm). The remaining parameters were fixed by simplifying the model [Sato et al., 2014].The highlands, highland ejecta, and swirl (Reiner Gamma) showed clearly higher w than the mare and mare ejecta. The derived c values were lower (less backscattering) for the swirl and higher (more backscattering) for the highlands (and ejecta) relative to the other sites. Forward scattering materials such as unconsolidated transparent crystalline materials might be relatively enriched in the swirl. In the highlands, anorthositic agglutinates with dense internal scattering could be responsible for the strong backscattering. The mare and mare ejecta showed continuously decreasing c from UV to visible wavelengths. This might be caused by the FeO-rich pyroxene

  20. Photometric Study of IC 2156

    NASA Astrophysics Data System (ADS)

    Tadross, A. L.; Hendy, Y. H. M.

    2016-04-01

    We present an optical UBVRI photometric analysis of the poorly studied open star cluster IC 2156 using Sloan Digital Sky Survey data in order to estimate its astrophysical properties. We compare these with results from our previous studies that relied on the 2MASS JHK near-infrared photometry. The stellar density distributions and color-magnitude diagrams of the cluster are used to determine its geometrical structure, real radius, core and tidal radii, and its distance from the Sun, the Galactic plane, and the Galactic center. We also estimate, the age, color excesses, reddening-free distance modulus, membership, total mass, luminosity function, mass function, and relaxation time of the cluster.

  1. Surface Titrations of Perlite Suspensions.

    PubMed

    Alkan; Do

    1998-11-01

    The surface charge behaviour of unexpanded and expanded perlite samples in KNO3 and NaCl solutions were investigated as a function of pH and ionic strength. The solutions of KNO3 and NaCl ranging from 10(-3) to 1.0 M were used. The potentiometric titration method was used to determine the surface charge of perlite samples. It was confirmed that the perlite samples had no the point of zero charge and was negatively charged in the pH range of 3-10. The double extrapolation method was used for determining the intrinsic equilibrium constants for simple ionization and complex ionization reactions. The values obtained are pKinta2 = 2.5 and p*KintK+ = 2.3 in KNO3 solutions and pKinta2 = 3.0 and p*KintNa+ = 2.4 in NaCl solutions for unexpanded perlite, and pKinta2 = 2.6 and p*KintK+ = 2.4 in KNO3 solutions and pKinta2 = 2.7 and pKintNa+ = 2.4 in NaCl solutions for expanded perlite. Copyright 1998 Academic Press.

  2. Sloan Digital Sky Survey Photometric Calibration Revisited

    NASA Astrophysics Data System (ADS)

    Marriner, J.

    2016-05-01

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  3. Sloan Digital Sky Survey Photometric Calibration Revisited

    SciTech Connect

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  4. The use of graphite electrodes in potentiometric titrations

    SciTech Connect

    Selig, W.S.

    1987-04-01

    The use of various types of graphite as indicator electrodes in potentiometry has been limited to acid-base and redox titrations. We have expanded the range of feasible titrations to: (1) precipitation titrations; (2) acid-base titrations; (3) compleximetric titrations; and (4) redox titrations. Graphite covered with an organic membrane containing poly(vinyl chloride) (PVC) and a plasticizer is particularly useful in monitoring the endpoints of titrations in which insoluble ion-pairs are formed. The potentiometric titration of fluoride vs La(III) or Th(IV), or of sulfate vs Pb (II) or Ba(II), which can be monitored with a plain carbon rod, is discussed.

  5. Acid-base titrations by stepwise addition of equal volumes of titrant with special reference to automatic titrations-II Theory of titration of mixtures of acids, polyprotic acids, acids in mixture with weak bases, and ampholytes.

    PubMed

    Pehrsson, L; Ingman, F; Johansson, S

    A general method for evaluating titration data for mixtures of acids and for acids in mixture with weak bases is presented. Procedures are given that do not require absolute [H]-data, i.e., relative [H]-data may be used. In most cases a very rough calibration of the electrode system is enough. Further, for simple systems, very approximate values of the stability constants are sufficient. As examples, the titration of the following are treated in some detail: a mixture of two acids, a diprotic acid, an acid in presence of its conjugate base, and an ampholyte.

  6. Lab on paper: iodometric titration on a printed card.

    PubMed

    Myers, Nicholas M; Kernisan, Emalee N; Lieberman, Marya

    2015-04-01

    A paper test card has been engineered to perform an iodometric titration, an application that requires storage and mixing on demand of several mutually incompatible reagents. The titration is activated when a user applies a test solution to the test card: the dried reagents are reconstituted and combined through a surface-tension-enabled mixing (STEM) mechanism. The device quantifies 0.8-15 ppm of iodine atoms from iodate in aqueous solutions. This is useful, for example, to quantify iodine levels in fortified salt. A blinded internal laboratory validation established the accuracy as 1.4 ppm I and the precision as 0.9 ppm I when the test card was read by newly trained users. Using computer software to process images, the accuracy and precision both improved to 0.9 ppm I. The paper card can also detect substandard β lactam antibiotics using an iodometric back-titration. When used to quantify amoxicillin, good distinction is achieved between solutions that differ by 0.15 mg/mL over a working range of 0-0.9 mg/mL. The test card was designed to meet the World Health Organization ASSURED criteria for use in low resource settings, where laboratory-based analytical procedures are often not available.

  7. Micro coulometric titration in a liquid drop.

    PubMed

    Kanyanee, Tinakorn; Fuekhad, Pongwasin; Grudpan, Kate

    2013-10-15

    Miniaturized coulometric titration in a liquid drop has been investigated. Assays of ascorbic acid and thiosulfate with iodine titration were chosen as models. Constant volumes of falling liquid drops containing sample or reagent are manipulated via gravimetrical force to move along a slope hydrophobic path and directed to stop or to move out from an electrode. Such manipulation is useful for delivery of sample and reagents, in a way of flow without tubing. Electrochemical generation of titrant, in this case, iodine, is started at the electrode and micro coulometric titration can be performed in a drop by applying constant current. Timing in the titration can be made via naked eye with a stopwatch or via recording with a webcam camera connecting to a computer to detect the change due to the blue color complex of the excess iodine and starch.

  8. Micro coulometric titration in a liquid drop.

    PubMed

    Kanyanee, Tinakorn; Fuekhad, Pongwasin; Grudpan, Kate

    2013-10-15

    Miniaturized coulometric titration in a liquid drop has been investigated. Assays of ascorbic acid and thiosulfate with iodine titration were chosen as models. Constant volumes of falling liquid drops containing sample or reagent are manipulated via gravimetrical force to move along a slope hydrophobic path and directed to stop or to move out from an electrode. Such manipulation is useful for delivery of sample and reagents, in a way of flow without tubing. Electrochemical generation of titrant, in this case, iodine, is started at the electrode and micro coulometric titration can be performed in a drop by applying constant current. Timing in the titration can be made via naked eye with a stopwatch or via recording with a webcam camera connecting to a computer to detect the change due to the blue color complex of the excess iodine and starch. PMID:24054589

  9. Potentiometric titrations using pencil and graphite sensors

    SciTech Connect

    Selig, W.S.

    1984-01-01

    The cost of various commercial indicating electrodes ranges from about $40 for pH electrodes to as much as $355 for a potassium ion-selective electrode. This cost can be reduced to less than $1.50, and in some cases to mere pennies by making sensors from graphite rods and pencils for use in potentiometric titrations. The same sensor can be used for many types of these titrations (acid/base, compleximetric, precipitation, and redox). 8 references, 2 tables.

  10. [Semiautomatic potentiometric titration of gastric juice].

    PubMed

    Mnuskina, M M; Meerov, G I; Nadezhina, L S; Semenov, V P; Chekanina, M I; Savchenko, V P; Grinzaĭd, E L

    1990-01-01

    Using commercial equipment manufactured in this country, the authors have assembled a unit for semiautomatic potentiometric titration and developed a method for such titration, permitting a rapid determination of free and bound HCl and the total acidity of the gastric juice. The equipment and method are recommended for wide use at laboratories of therapeutic institutions, of biologic factories manufacturing medicinal commercial gastric juice, and of research institutes.

  11. A photometric study of the Orion OB 1 association. 2: Photometric analysis

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.; Hesser, J. E.

    1976-01-01

    The procedures adopted for analysis of photometric data in terms of color excesses, intrinsic color indexes, absolute visual magnitudes, and rotational-velocity effects are discussed in detail for Orion association B-, intermediate (I)-, and AF-type stars. The effects of the nebular environment and a comparison of various calibrations of Balmer-line and four-color indexes are considered for the determination of individual absolute magnitudes for B-type stars. When absolute magnitudes of stars in the region of the Orion Nebula are determined from the beta index, emission mechanisms appear to spuriously brighten them. A detailed comparison of absolute magnitudes derived from Balmer-line indexes and MK spectral-type calibrations is presented. The data are also examined with regard to the effects of polarization and infrared excesses. The results suggest a complex combination of intracluster and circumstellar origins for these processes.

  12. Photometric invariant stereo matching method.

    PubMed

    Gu, Feifei; Zhao, Hong; Zhou, Xiang; Li, Jinjun; Bu, Penghui; Zhao, Zixin

    2015-12-14

    A robust stereo matching method based on a comprehensive mathematical model for color formation process is proposed to estimate the disparity map of stereo images with noise and photometric variations. The band-pass filter with DoP kernel is firstly used to filter out noise component of the stereo images. Then the log-chromaticity normalization process is applied to eliminate the influence of lightning geometry. All the other factors that may influence the color formation process are removed through the disparity estimation process with a specific matching cost. Performance of the developed method is evaluated by comparing with some up-to-date algorithms. Experimental results are presented to demonstrate the robustness and accuracy of the method. PMID:26698970

  13. Plaque titration and inhibition tests for bovine parvovirus.

    PubMed

    Durham, P J; Johnson, R H

    1984-08-01

    Bovine parvovirus readily produced plaques when inoculated into 60% confluent, actively growing bovine embryonic lung cells. Incorporation of DEAE-dextran, MgCl2 and DMSO in the agarose overlay medium was found to improve plaque production, especially with the latter chemical. In contrast, protamine sulphate inhibited plaque development. It was found that plaque titration and plaque inhibition tests could be conveniently carried out in 24-well cell culture plates, using an agarose overlay containing DMSO, DEAE-dextran and foetal calf serum. The procedures were highly sensitive, when compared with other established techniques.

  14. CuBANz: Photometric redshift estimator

    NASA Astrophysics Data System (ADS)

    Samui, Saumyadip; Pal, Shanoli Samui

    2016-09-01

    CuBANz is a photometric redshift estimator code for high redshift galaxies that uses the back propagation neural network along with clustering of the training set, making it very efficient. The training set is divided into several self learning clusters with galaxies having similar photometric properties and spectroscopic redshifts within a given span. The clustering algorithm uses the color information (i.e. u-g, g-r etc.) rather than the apparent magnitudes at various photometric bands, as the photometric redshift is more sensitive to the flux differences between different bands rather than the actual values. The clustering method enables accurate determination of the redshifts. CuBANz considers uncertainty in the photometric measurements as well as uncertainty in the neural network training. The code is written in C.

  15. Photometric Redshift Techniques in Big-data Era

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Xia; Zhao, Yong-Heng

    Photometric data increase with large survey projects running. The huge volume of data influences the means and methods to deal with them. As such, the techniques of photometric redshift estimation based on photometric data must be developed and improved.

  16. Theory of titration curves-VII The properties of derivative titration curves for strong acid-strong base and other isovalent ion-combination titrations.

    PubMed

    Meites, T; Meites, L

    1970-06-01

    This paper deals with isovalent ion-combination titrations based on reactions that can be represented by the equation M(n+) + X(n-) --> MX, where the activity of the product MX is invariant throughout a titration, and with the derivative titration curves obtained by plotting d[M(+)]/dfversus f for such titrations. It describes some of the ways in which such curves can be obtained; it compares and contrasts them both with potentiometric titration curves, which resemble them in shape, and with segmented titration curves, from which they are derived; and it discusses their properties in detail.

  17. Determination of metal speciation by reverse titrations.

    PubMed

    Nuester, Jochen; van den Berg, Constant M G

    2005-01-01

    A new method is proposed to determine metal speciation by varying the concentration of a competing ligand at a constant metal concentration, with detection by cathodic stripping voltammetry. The free metal ion concentration is gradually lowered from its natural level while the method probes progressively deeper into the already complexed metal fraction: it is therefore a reverse titration rather than the forward titration which is used for conventional complexing ligand titrations. The sensitivity is greatest at the lowest free metal ion concentration, where it matters most, and the method can be carried out in a single sample aliquot in the voltammetric cell. The method is applied here to copper speciation, but in principle, it can also be used for other metals. Modeling shows that this method has good sensitivity at ligand concentrations near the metal concentration (lower as well as greater). Comparative measurements of copper speciation using reverse and forward titrations of representative water samples of oceanic and coastal origin show good agreement. The data showed that these samples did not contain low levels of strong ligands in addition to the ligands detected by the forward titrations.

  18. Photometric Studies of GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Edwin; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the SMARTS (Small and Medium Aperture Research Telescope System) 0.9-m at CTIO for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? In this paper we report on the photometric results. For a sample of 50 objects, more than 90 calibrated sequences of R-B-V-I-R magnitudes have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus

  19. Sloan Digital Sky Survey photometric telescope automation and observing software

    SciTech Connect

    Eric H. Neilsen, Jr. et al.

    2002-10-16

    The photometric telescope (PT) provides observations necessary for the photometric calibration of the Sloan Digital Sky Survey (SDSS). Because the attention of the observing staff is occupied by the operation of the 2.5 meter telescope which takes the survey data proper, the PT must reliably take data with little supervision. In this paper we describe the PT's observing program, MOP, which automates most tasks necessary for observing. MOP's automated target selection is closely modeled on the actions a human observer might take, and is built upon a user interface that can be (and has been) used for manual operation. This results in an interface that makes it easy for an observer to track the activities of the automating procedures and intervene with minimum disturbance when necessary. MOP selects targets from the same list of standard star and calibration fields presented to the user, and chooses standard star fields covering ranges of airmass, color, and time necessary to monitor atmospheric extinction and produce a photometric solution. The software determines when additional standard star fields are unnecessary, and selects survey calibration fields according to availability and priority. Other automated features of MOP, such as maintaining the focus and keeping a night log, are also built around still functional manual interfaces, allowing the observer to be as active in observing as desired; MOP's automated features may be used as tools for manual observing, ignored entirely, or allowed to run the telescope with minimal supervision when taking routine data.

  20. On the Estimation of Photometric Spectral Types

    NASA Astrophysics Data System (ADS)

    Oblak, E.; Chareton, M.

    1981-09-01

    We have estimated a photometric spectral type based on indices of the uvbyβ photometry for the normal stars of the Hauck and Mermilliod (1975) compilation. In this sample 1563 stars have no MK spectral types for 440 stars it is difficult or impossible to estimate a spectral type from the photometry for 436 stars having an estimated photometric spectral type we have found an MK spectral type on the literature which allowed a comparative study. We give the absolute magnitudes for the MK and photometric spectral types.

  1. Determination of quaternary ammonium compounds by potentiometric titration with an ionic surfactant electrode: single-laboratory validation.

    PubMed

    Price, Randi; Wan, Ping

    2010-01-01

    A potentiometric titration for determining the quaternary ammonium compounds (QAC) commonly found in antimicrobial products was validated by a single laboratory. Traditionally, QACs were determined by using a biphasic (chloroform and water) manual titration procedure. Because of safety considerations regarding chloroform, as well as the subjectivity of color indicator-based manual titration determinations, an automatic potentiometric titration procedure was tested with quaternary nitrogen product formulations. By using the Metrohm Titrando system coupled with an ionic surfactant electrode and an Ag/AgCl reference electrode, titrations were performed with various QAC-containing formulation products/matrixes; a standard sodium lauryl sulfate solution was used as the titrant. Results for the products tested are sufficiently reproducible and accurate for the purpose of regulatory product enforcement. The robustness of the method was measured by varying pH levels, as well as by comparing buffered versus unbuffered titration systems. A quantitation range of 1-1000 ppm quaternary nitrogen was established. Eight commercially available antimicrobial products covering a variety of matrixes were assayed; the results obtained were comparable to those obtained by the manual titration method. Recoveries of 94 to 104% were obtained for spiked samples.

  2. Determination of quaternary ammonium compounds by potentiometric titration with an ionic surfactant electrode: single-laboratory validation.

    PubMed

    Price, Randi; Wan, Ping

    2010-01-01

    A potentiometric titration for determining the quaternary ammonium compounds (QAC) commonly found in antimicrobial products was validated by a single laboratory. Traditionally, QACs were determined by using a biphasic (chloroform and water) manual titration procedure. Because of safety considerations regarding chloroform, as well as the subjectivity of color indicator-based manual titration determinations, an automatic potentiometric titration procedure was tested with quaternary nitrogen product formulations. By using the Metrohm Titrando system coupled with an ionic surfactant electrode and an Ag/AgCl reference electrode, titrations were performed with various QAC-containing formulation products/matrixes; a standard sodium lauryl sulfate solution was used as the titrant. Results for the products tested are sufficiently reproducible and accurate for the purpose of regulatory product enforcement. The robustness of the method was measured by varying pH levels, as well as by comparing buffered versus unbuffered titration systems. A quantitation range of 1-1000 ppm quaternary nitrogen was established. Eight commercially available antimicrobial products covering a variety of matrixes were assayed; the results obtained were comparable to those obtained by the manual titration method. Recoveries of 94 to 104% were obtained for spiked samples. PMID:21140668

  3. Photometric Study of Uranian Satellites

    NASA Technical Reports Server (NTRS)

    Kesten, Philip R.

    1998-01-01

    The best summary of my work at NASA is expressed in the following abstract, submitted the Division for Planetary Science of the American Astronomical Society and to be presented at the annual meeting in Madison in October. We report photometric measurements of Uranian satellites Miranda, Ariel, Umbriel and Titania (10.4 Aug. 1995), and Neptune's satellite Triton (21.2 Sept. 1995) with the infrared camera (IRCAM) and standard J (1.13 - 1.42 microns), H (1.53 - 1.81 microns), and K (2.00 - 2.41 microns) filters at the 3.8-m UKIRT telescope on Mauna Kea. The individual images frames are 256 x 256 pixels with a platescale of .286 arcsec/pixel, resulting in a 1.22 arc min field of view. This summer brought the IR photometry measurements nearly to a close. As indicated by the abstract above, I will present this work at the annual DPS meeting in October. In anticipation of the opening of the new Carl Sagan Laboratory for Cosmochemisty, of which I will be a participating member, I also devoted a considerable fraction of the summer to learning the biochemistry which underlies the experiments to be conducted. To put the end of the summary close to the beginning, it was a most productive summer.

  4. Photometrical Observations "SBIRS GEO-2"

    NASA Astrophysics Data System (ADS)

    Sukhov, P. P.; Epishev, V. P.; Karpenko, G. F.; Sukhov, K. P.; Kudak, V. I.

    Photometrical observations GSS "SBIRS GEO 2" in B,V,R filters were carried near the equinoxes 2014-2015. Used velocity electrophotometer based on the FEU-79 in the pulse-counting mode. Received more than 25 light curves. From the known dimensions are defined; effective reflecting area - Sγλ, the spectral reflectance index - γλ, periods of light variation. Color-indices showed that in the reflected light flux from the GSS prevails "red" component. In the light curves are periodically dips and specular flash. This shows that GSS orbit is not in a static position specified triaxial orientation as in dynamic motion. Assumed following dynamics of the satellite "SBIRS GEO 2" in orbit. Helical scanning the Earth's surface visible infrared sensors satellite occurs with a period P1 = 15.66 sec. and swinging of the GSS about the direction of the motion vector of the satellite in an orbit with P2 = 62.64 sec., from the northern to the southern pole. Thus, during the period of swinging GSS going on 2 scan the visible part of the northern and southern hemispheres. In some dates observations dynamics work satellite in orbit changed.

  5. Photometric properties of Triton hazes

    NASA Technical Reports Server (NTRS)

    Hillier, J.; Veverka, J.

    1994-01-01

    Voyager imaging observations of Triton have been used to investigate the characteristics of the atmospheric hazes on Triton at three wavelengths: violet (0.41 micrometers), blue (0.48 micrometers), and green (0.56 micrometers). The globally averaged optical depth is wavelength dependent, varying from 0.034 in green to 0.063 in violet. These photometric results are dominated by the properties of localized discrete clouds rather than by those of the thinner, more widespread haze known to occur on Triton. The cloud particles are bright, with single-scattering albedos near unity at all three wavelengths, suggestive of a transparent icy condensate. The asymmetry parameter (+0.6) and the wavelength dependence of the optical depth both indicate cloud particles 0.2-0.4 micrometers in radius. The clouds are concentrated at 50-60 deg S latitude, where opacities up to three times the global average are observed. This is the same latitude region where most of the evidence for current surface activity is found, suggesting that the clouds may be related to the plumes or at least to some process connected with the sublimation of the south polar cap. The effects of possible temporal variations in the haze opacity are examined. Increases in the haze opacity tend to redden Triton. However, the degree of reddening is not sufficient to explain the full range of observed changed in Triton over the past decade; variations in the surface properties appear to be necessary.

  6. Coulometric Titration of Ethylenediaminetetraacetate (EDTA) with Spectrophotometric Endpoint Detection: An Experiment for the Instrumental Analysis Laboratory

    ERIC Educational Resources Information Center

    Williams, Kathryn R.; Young, Vaneica Y.; Killian, Benjamin J.

    2011-01-01

    Ethylenediaminetetraacetate (EDTA) is commonly used as an anticoagulant in blood-collection procedures. In this experiment for the instrumental analysis laboratory, students determine the quantity of EDTA in commercial collection tubes by coulometric titration with electrolytically generated Cu[superscript 2+]. The endpoint is detected…

  7. Titration of the bacteriorhodopsin Schiff base involves titration of an additional protein residue.

    PubMed

    Zadok, Uri; Asato, Alfred E; Sheves, Mordechai

    2005-06-14

    The retinal protein protonated Schiff base linkage plays a key role in the function of bacteriorhodopsin (bR) as a light-driven proton pump. In the unphotolyzed pigment, the Schiff base (SB) is titrated with a pK(a) of approximately 13, but following light absorption, it experiences a decrease in the pK(a) and undergoes several alterations, including a deprotonation process. We have studied the SB titration using retinal analogues which have intrinsically lower pK(a)'s which allow for SB titrations over a much lower pH range. We found that above pH 9 the channel for the SB titration is perturbed, and the titration rate is considerably reduced. On the basis of studies with several mutants, it is suggested that the protonation state of residue Glu204 is responsible for the channel perturbation. We suggest that above pH 12 a channel for the SB titration is restored probably due to titration of an additional protein residue. The observations may imply that during the bR photocycle and M photointermediate formation the rate of Schiff base protonation from the bulk is decreased. This rate decrease may be due to the deprotonation process of the "proton-releasing complex" which includes Glu204. In contrast, during the lifetime of the O intermediate, the protonated SB is exposed to the bulk. Possible implications for the switch mechanism, and the directionality of the proton movement, are discussed.

  8. Novel approaches to analysis by flow injection gradient titration.

    PubMed

    Wójtowicz, Marzena; Kozak, Joanna; Kościelniak, Paweł

    2007-09-26

    Two novel procedures for flow injection gradient titration with the use of a single stock standard solution are proposed. In the multi-point single-line (MP-SL) method the calibration graph is constructed on the basis of a set of standard solutions, which are generated in a standard reservoir and subsequently injected into the titrant. According to the single-point multi-line (SP-ML) procedure the standard solution and a sample are injected into the titrant stream from four loops of different capacities, hence four calibration graphs are able to be constructed and the analytical result is calculated on the basis of a generalized slope of these graphs. Both approaches have been tested on the example of spectrophotometric acid-base titration of hydrochloric and acetic acids with using bromothymol blue and phenolphthalein as indicators, respectively, and sodium hydroxide as a titrant. Under optimized experimental conditions the analytical results of precision less than 1.8 and 2.5% (RSD) and of accuracy less than 3.0 and 5.4% (relative error (RE)) were obtained for MP-SL and SP-ML procedures, respectively, in ranges of 0.0031-0.0631 mol L(-1) for samples of hydrochloric acid and of 0.1680-1.7600 mol L(-1) for samples of acetic acid. The feasibility of both methods was illustrated by applying them to the total acidity determination in vinegar samples with precision lower than 0.5 and 2.9% (RSD) for MP-SL and SP-ML procedures, respectively.

  9. Colorimetric Titration Experiment for the Undergraduate Laboratory.

    ERIC Educational Resources Information Center

    Lopez, Edwin; Vassos, Basil H.

    1984-01-01

    Describes a colorimetric titration instrument usable in the undergraduate laboratory that fulfills the objectives of ruggedness, freedom from ambient light interference, and low cost. Although accessories can be added (raising the price), the basic instrument is low priced and can be used manually with a simple voltmeter. (JN)

  10. Isothermal Titration Calorimetry in the Student Laboratory

    ERIC Educational Resources Information Center

    Wadso, Lars; Li, Yujing; Li, Xi

    2011-01-01

    Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a…

  11. Titration Calculations with Computer Algebra Software

    ERIC Educational Resources Information Center

    Lachance, Russ; Biaglow, Andrew

    2012-01-01

    This article examines the symbolic algebraic solution of the titration equations for a diprotic acid, as obtained using "Mathematica," "Maple," and "Mathcad." The equilibrium and conservation equations are solved symbolically by the programs to eliminate the approximations that normally would be performed by the student. Of the three programs,…

  12. Problems in the interpretation of nonaqueous titrations.

    PubMed

    Buvári-Barcza, A; Barcza, L

    2005-04-01

    Most phenomena (like promoting and leveling as well as differentiating effects) of common nonaqueous titrations can be explained by the Brönsted's concept combined with the hydrogen bond theory but some open problems are shown in connection with the use of formic acid and/or acetic anhydride.

  13. Rapid titration of viruses by flow cytometry.

    PubMed

    Drayman, Nir; Oppenheim, Ariella

    2011-06-01

    Traditionally, the most common methods used to titrate virus stocks are the plaque assay and the hemagglutination assay. The protocol presented here is based on the detection of viral-expressed proteins in infected cells by flow cytometry. It is simpler and more rapid than the traditional plaque-forming assay and it enables high-throughput analyses.

  14. Tracer monitored titrations: measurement of total alkalinity.

    PubMed

    Martz, Todd R; Dickson, Andrew G; DeGrandpre, Michael D

    2006-03-15

    We introduce a new titration methodology, tracer monitored titration (TMT), in which analyses are free of volumetric and gravimetric measurements and insensitive to pump precision and reproducibility. Spectrophotometric monitoring of titrant dilution, rather than volume increment, lays the burden of analytical performance solely on the spectrophotometer. In the method described here, the titrant is a standardized mixture of acid-base indicator and strong acid. Dilution of a pulse of titrant in a titration vessel is tracked using the total indicator concentration measured spectrophotometrically. The concentrations of reacted and unreacted indicator species, derived from Beer's law, are used to calculate the relative proportions of titrant and sample in addition to the equilibrium position (pH) of the titration mixture. Because the method does not require volumetric or gravimetric additions of titrant, simple low-precision pumps can be used. Here, we demonstrate application of TMT for analysis of total alkalinity (A(T)). High-precision, high-accuracy seawater A(T) measurements are crucial for understanding, for example, the marine CaCO3 budget and saturation state, anthropogenic CO2 penetration into the oceans, calcareous phytoplankton blooms, and coral reef dynamics. We present data from 286 titrations on three types of total alkalinity standards: Na2CO3 in 0.7 mol kg x soln(-1) NaCl, NaOH in 0.7 mol kg x soln(-1) NaCl, and a seawater Certified Reference Material (CRM). Based on Na2CO3 standards, the accuracy and precision are +/-0.2 and +/-0.1% (4 and 2 micromol kg x soln(-1) for A(T) approximately 2100-2500 micromol kg x soln(-1), n = 242), using low-precision solenoid pumps to introduce sample and titrant. Similar accuracy and precision were found for analyses run 42 days after the initial experiments. Excellent performance is achieved by optimizing the spectrophotometric detection system and relying upon basic chemical thermodynamics for calculating the

  15. Surfactant titration of nanoparticle-protein corona.

    PubMed

    Maiolo, Daniele; Bergese, Paolo; Mahon, Eugene; Dawson, Kenneth A; Monopoli, Marco P

    2014-12-16

    Nanoparticles (NP), when exposed to biological fluids, are coated by specific proteins that form the so-called protein corona. While some adsorbing proteins exchange with the surroundings on a short time scale, described as a "dynamic" corona, others with higher affinity and long-lived interaction with the NP surface form a "hard" corona (HC), which is believed to mediate NP interaction with cellular machineries. In-depth NP protein corona characterization is therefore a necessary step in understanding the relationship between surface layer structure and biological outcomes. In the present work, we evaluate the protein composition and stability over time and we systematically challenge the formed complexes with surfactants. Each challenge is characterized through different physicochemical measurements (dynamic light scattering, ζ-potential, and differential centrifugal sedimentation) alongside proteomic evaluation in titration type experiments (surfactant titration). 100 nm silicon oxide (Si) and 100 nm carboxylated polystyrene (PS-COOH) NPs cloaked by human plasma HC were titrated with 3-[(3-Cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS, zwitterionic), Triton X-100 (nonionic), sodium dodecyl sulfate (SDS, anionic), and dodecyltrimethylammonium bromide (DTAB, cationic) surfactants. Composition and density of HC together with size and ζ-potential of NP-HC complexes were tracked at each step after surfactant titration. Results on Si NP-HC complexes showed that SDS removes most of the HC, while DTAB induces NP agglomeration. Analogous results were obtained for PS NP-HC complexes. Interestingly, CHAPS and Triton X-100, thanks to similar surface binding preferences, enable selective extraction of apolipoprotein AI (ApoAI) from Si NP hard coronas, leaving unaltered the dispersion physicochemical properties. These findings indicate that surfactant titration can enable the study of NP-HC stability through surfactant variation and also selective separation

  16. PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS

    SciTech Connect

    Brown, Robert A.

    2009-09-10

    We define and analyze the photometric orbit (PhO) of an extrasolar planet observed in reflected light. In our definition, the PhO is a Keplerian entity with six parameters: semimajor axis, eccentricity, mean anomaly at some particular time, argument of periastron, inclination angle, and effective radius, which is the square root of the geometric albedo times the planetary radius. Preliminarily, we assume a Lambertian phase function. We study in detail the case of short-period giant planets (SPGPs) and observational parameters relevant to the Kepler mission: 20 ppm photometry with normal errors, 6.5 hr cadence, and three-year duration. We define a relevant 'planetary population of interest' in terms of probability distributions of the PhO parameters. We perform Monte Carlo experiments to estimate the ability to detect planets and to recover PhO parameters from light curves. We calibrate the completeness of a periodogram search technique, and find structure caused by degeneracy. We recover full orbital solutions from synthetic Kepler data sets and estimate the median errors in recovered PhO parameters. We treat in depth a case of a Jupiter body-double. For the stated assumptions, we find that Kepler should obtain orbital solutions for many of the 100-760 SPGP that Jenkins and Doyle estimate Kepler will discover. Because most or all of these discoveries will be followed up by ground-based radial velocity observations, the estimates of inclination angle from the PhO may enable the calculation of true companion masses: Kepler photometry may break the 'msin i' degeneracy. PhO observations may be difficult. There is uncertainty about how low the albedos of SPGPs actually are, about their phase functions, and about a possible noise floor due to systematic errors from instrumental and stellar sources. Nevertheless, simple detection of SPGPs in reflected light should be robust in the regime of Kepler photometry, and estimates of all six orbital parameters may be feasible in

  17. Characterization of protein-protein interactions by isothermal titration calorimetry.

    PubMed

    Velazquez-Campoy, Adrian; Leavitt, Stephanie A; Freire, Ernesto

    2015-01-01

    The analysis of protein-protein interactions has attracted the attention of many researchers from both a fundamental point of view and a practical point of view. From a fundamental point of view, the development of an understanding of the signaling events triggered by the interaction of two or more proteins provides key information to elucidate the functioning of many cell processes. From a practical point of view, understanding protein-protein interactions at a quantitative level provides the foundation for the development of antagonists or agonists of those interactions. Isothermal Titration Calorimetry (ITC) is the only technique with the capability of measuring not only binding affinity but the enthalpic and entropic components that define affinity. Over the years, isothermal titration calorimeters have evolved in sensitivity and accuracy. Today, TA Instruments and MicroCal market instruments with the performance required to evaluate protein-protein interactions. In this methods paper, we describe general procedures to analyze heterodimeric (porcine pancreatic trypsin binding to soybean trypsin inhibitor) and homodimeric (bovine pancreatic α-chymotrypsin) protein associations by ITC.

  18. Automatic set-point titration for monitoring nitrification in SBRs.

    PubMed

    Fiocchi, N; Ficara, E; Bonelli, S; Canziani, R; Ciappelloni, F; Mariani, S; Pirani, M; Ratini, P; Mazouni, D; Harmand, J

    2008-01-01

    Nitrification is usually the bottleneck of biological nitrogen removal processes. In SBRs systems, it is not often enough to monitor dissolved oxygen, pH and ORP to spot problems which may occur in nitrification processes. Therefore, automated supervision systems should be designed to include the possibility of monitoring the activity of nitrifying populations. Though the applicability of set-point titration for monitoring biological processes has been widely demonstrated in the literature, the possibility of an automated procedure is still at its early stage of industrial development. In this work, the use of an at-line automated titrator named TITAAN (TITrimetric Automated ANalyser) is presented. The completely automated sensor enables us to track nitrification rate trend with time in an SBR, detecting the causes leading to slower specific nitrification rates. It was also possible to perform early detection of toxic compounds in the influent by assessing their effect on the nitrifying biomass. Nitrifications rates were determined with average errors+/-10% (on 26 tests), never exceeding 20% as compared with UV-spectrophotometric determinations.

  19. Automatic set-point titration for monitoring nitrification in SBRs.

    PubMed

    Fiocchi, N; Ficara, E; Bonelli, S; Canziani, R; Ciappelloni, F; Mariani, S; Pirani, M; Ratini, P; Mazouni, D; Harmand, J

    2008-01-01

    Nitrification is usually the bottleneck of biological nitrogen removal processes. In SBRs systems, it is not often enough to monitor dissolved oxygen, pH and ORP to spot problems which may occur in nitrification processes. Therefore, automated supervision systems should be designed to include the possibility of monitoring the activity of nitrifying populations. Though the applicability of set-point titration for monitoring biological processes has been widely demonstrated in the literature, the possibility of an automated procedure is still at its early stage of industrial development. In this work, the use of an at-line automated titrator named TITAAN (TITrimetric Automated ANalyser) is presented. The completely automated sensor enables us to track nitrification rate trend with time in an SBR, detecting the causes leading to slower specific nitrification rates. It was also possible to perform early detection of toxic compounds in the influent by assessing their effect on the nitrifying biomass. Nitrifications rates were determined with average errors+/-10% (on 26 tests), never exceeding 20% as compared with UV-spectrophotometric determinations. PMID:18701782

  20. An Olfactory Indicator for Acid-Base Titrations.

    ERIC Educational Resources Information Center

    Flair, Mark N.; Setzer, William N.

    1990-01-01

    The use of an olfactory acid-base indicator in titrations for visually impaired students is discussed. Potential olfactory indicators include eugenol, thymol, vanillin, and thiophenol. Titrations performed with each indicator with eugenol proved to be successful. (KR)

  1. Determination of carbonate carbon in geological materials by coulometric titration

    USGS Publications Warehouse

    Engleman, E.E.; Jackson, L.L.; Norton, D.R.

    1985-01-01

    A coulometric titration is used for the determination of carbonate carbon in geological materials. Carbon dioxide is evolved from the sample by the addition of 2 M perchloric acid, with heating, and is determined by automated coulometric titration. The coulometric titration showed improved speed and precision with comparable accuracy to gravimetric and gasometric techniques. ?? 1985.

  2. Simple and Automated Coulometric Titration of Acid Using Nonisolated Electrodes

    ERIC Educational Resources Information Center

    Kuntzleman, Thomas S.; Kenney, Joshua B.; Hasbrouck, Scott; Collins, Michael J.; Amend, John R.

    2011-01-01

    Coulometric titrations involve the quantification of analyte by measurements of current and time. In most coulometric titrations, the anode and cathode are placed in isolated cells that are connected by a salt bridge. By contrast, the experiments described here involve coulometric titrations (of acidic protons in solution) using a silver anode and…

  3. The Candela and Photometric and Radiometric Measurements

    PubMed Central

    Parr, Albert C.

    2001-01-01

    The national measurement system for photometric and radiometric quantities is presently based upon techniques that make these quantities traceable to a high-accuracy cryogenic radiometer. The redefinition of the candela in 1979 provided the opportunity for national measurement laboratories to base their photometric measurements on optical detector technology rather than on the emission from high-temperature blackbody optical sources. The ensuing technical developments of the past 20 years, including the significant improvements in cryogenic radiometer performance, have provided the opportunity to place the fundamental maintenance of photometric quantities upon absolute detector based technology as was allowed by the 1979 redefinition. Additionally, the development of improved photodetectors has had a significant impact on the methodology in most of the radiometric measurement areas. This paper will review the status of the NIST implementation of the technical changes mandated by the 1979 redefinition of the candela and its effect upon the maintenance and dissemination of optical radiation measurements. PMID:27500020

  4. Photometric analysis of Collinder Cluster 223

    NASA Astrophysics Data System (ADS)

    Duplancic Videla, M. F.; Molina, S.; González, J. F.

    We present photometric observations of the open-cluster Collinder 223 (RA= 10h 30m 38s , dec =-60° 06' 39'' ), obtained from observation with the HSH telescope in CASLEO. This cluster has not been studied extensively, there is only one photoelectric photometric UBV study, done by Clariá and Lapasset (1991). A later study, done by Tadross (2004), reanalyzed the data, however, no other photometric measurements have been carried out until present. We observed seven fields in the cluster which were chosen prioritizing the zones of major stellar concentration. We obtained color-magnitude diagrams of the cluster, reaching stars two magnitudes weaker than those previously obtained by Clariá and Lapasset. The cluster sequence shows well in accordance with the isochrone corresponding to the age of 3.5 10E7 yr.

  5. Defining photometric peculiar type Ia supernovae

    SciTech Connect

    González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T.; Hsiao, E. Y.; Phillips, M. M.; Folatelli, G.; Anderson, J. P.

    2014-11-10

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  6. Digital movie-based on automatic titrations.

    PubMed

    Lima, Ricardo Alexandre C; Almeida, Luciano F; Lyra, Wellington S; Siqueira, Lucas A; Gaião, Edvaldo N; Paiva Junior, Sérgio S L; Lima, Rafaela L F C

    2016-01-15

    This study proposes the use of digital movies (DMs) in a flow-batch analyzer (FBA) to perform automatic, fast and accurate titrations. The term used for this process is "Digital movie-based on automatic titrations" (DMB-AT). A webcam records the DM during the addition of the titrant to the mixing chamber (MC). While the DM is recorded, it is decompiled into frames ordered sequentially at a constant rate of 26 frames per second (FPS). The first frame is used as a reference to define the region of interest (ROI) of 28×13pixels and the R, G and B values, which are used to calculate the Hue (H) values for each frame. The Pearson's correlation coefficient (r) is calculated between the H values of the initial frame and each subsequent frame. The titration curves are plotted in real time using the r values and the opening time of the titrant valve. The end point is estimated by the second derivative method. A software written in C language manages all analytical steps and data treatment in real time. The feasibility of the method was attested by application in acid/base test samples and edible oils. Results were compared with classical titration and did not present statistically significant differences when the paired t-test at the 95% confidence level was applied. The proposed method is able to process about 117-128 samples per hour for the test and edible oil samples, respectively, and its precision was confirmed by overall relative standard deviation (RSD) values, always less than 1.0%.

  7. Digital movie-based on automatic titrations.

    PubMed

    Lima, Ricardo Alexandre C; Almeida, Luciano F; Lyra, Wellington S; Siqueira, Lucas A; Gaião, Edvaldo N; Paiva Junior, Sérgio S L; Lima, Rafaela L F C

    2016-01-15

    This study proposes the use of digital movies (DMs) in a flow-batch analyzer (FBA) to perform automatic, fast and accurate titrations. The term used for this process is "Digital movie-based on automatic titrations" (DMB-AT). A webcam records the DM during the addition of the titrant to the mixing chamber (MC). While the DM is recorded, it is decompiled into frames ordered sequentially at a constant rate of 26 frames per second (FPS). The first frame is used as a reference to define the region of interest (ROI) of 28×13pixels and the R, G and B values, which are used to calculate the Hue (H) values for each frame. The Pearson's correlation coefficient (r) is calculated between the H values of the initial frame and each subsequent frame. The titration curves are plotted in real time using the r values and the opening time of the titrant valve. The end point is estimated by the second derivative method. A software written in C language manages all analytical steps and data treatment in real time. The feasibility of the method was attested by application in acid/base test samples and edible oils. Results were compared with classical titration and did not present statistically significant differences when the paired t-test at the 95% confidence level was applied. The proposed method is able to process about 117-128 samples per hour for the test and edible oil samples, respectively, and its precision was confirmed by overall relative standard deviation (RSD) values, always less than 1.0%. PMID:26592600

  8. Titration of recombinant woodchuck hepatitis virus DNA in adult woodchucks.

    PubMed

    Chen, H S; Miller, R H; Hornbuckle, W E; Tennant, B C; Cote, P J; Gerin, J L; Purcell, R H

    1998-02-01

    In vivo transfection of Eastern woodchucks (Marmota monax) with recombinant woodchuck hepatitis virus (WHV) DNA is effective in inducing virus infection for the study of replication, pathogenicity, and oncogenicity of wild-type and mutated WHV. The one drawback to this procedure is the need for preparation of large amounts of WHV DNA. Reduction of the amount of WHV DNA in the transfection protocol necessary to induce infection would save considerable time and resources. Therefore, we conducted a titration of WHV DNA, ranging from 50 micrograms to 50 pg of DNA, in adult woodchucks to determine the minimum infectious dose of recombinant WHV DNA. As little as 50 ng of transfected WHV DNA induced productive infection in adult woodchucks. Thus, transfection with large amounts of recombinant WHV DNA appears to be unnecessary.

  9. A new sensor for thermometric titrations.

    PubMed

    Najib, Fadhil M; Zewar, Sardir; Abdulla, Ahmad M

    2007-01-15

    A new thermometric sensor, which is a transistor (OC71), has been introduced to follow thermometric titrations successfully to clear end points. The sensor was suitable in both normal and differential modes of titration. It is possible to titrate down to 1.32micromol of HCl and 26.4micromol of H(3)BO(3)in a final 20ml solution with accuracy and precision of 1%, 2.2% and 1.4%, 2.2%, respectively. The sensor, in association with a pH glass electrode, was used for the determination of pK values of some well established weak acids such as, acetic acid (4.77), phosphoric acid (pK(1)=2.18, pK(2)=7.20 and pK(3)=12.32) as well as for a very weak acid of uncertain pK values H(3)BO(3) (pK(1)=9.20, pK(2)=12.7 and pK(3)=13.80). The sensor was also examined for kinetic catalytic determination of iron(III) in water, milk and pharmaceuticals.

  10. A monosegmented-flow Karl Fischer titrator.

    PubMed

    de Aquino, Emerson Vidal; Rohwedder, Jarbas José Rodrigues; Pasquini, Celio

    2007-02-28

    A monosegmented volumetric Karl Fischer titrator is described to mechanize the determination of water content in organic solvents. The system is based on the flow-batch characteristics of the monosegmented analysis concept and employs biamperometry to monitor the progress of the titration. The system shows accuracy and precision that are highly independent of the flow rate, does not require calibration, and is carried out in a closed system capable of minimizing contact of the sample and reagents with ambient moisture. Sample volumes in the range of 40-300muL are employed, depending on the water concentration. An automatic dilution is provided to deal with concentrated samples. The consumption of Karl Fischer reagent depends on the water content of the sample but is not larger than 100muL. The system was evaluated for determination of water in ethanol and methanol in the range 0.02-0.5% (w/w). The average relative precision estimated in that range (9-3%) is comparable to that obtained with a larger volume commercial system and no significant difference was observed between the results obtained for the two systems at the 95% confidence level. A complete titration can be performed in less than 5min employing the proposed system. PMID:19071447

  11. Photometric diversity of terrains on Triton

    NASA Technical Reports Server (NTRS)

    Hillier, J.; Veverka, J.; Helfenstein, P.; Lee, P.

    1994-01-01

    Voyager disk-resolved images of Triton in the violet (0.41 micrometers) and green (0.56 micrometer wavelengths have been analyzed to derive the photometric characteristics of terrains on Triton. Similar conclusions are found using two distinct but related definitions of photometric units, one based on color ratio and albedo properties (A. S. McEwen, 1990), the other on albedo and brightness ratios at different phase angles (P. Lee et al., 1992). A significant diversity of photometric behavior, much broader than that discovered so far on any other icy satellite, occurs among Triton's terrains. Remarkably, differences in photometric behavior do not correlate well with geologic terrain boundaries defined on the basis of surface morphology. This suggests that in most cases photometric properties on Triton are controlled by thin deposits superposed on underlying geologic units. Single scattering albedos are 0.98 or higher and asymmetry factors range from -0.35 to -0.45 for most units. The most distinct scattering behavior is exhibited by the reddish northern units already identified as the Anomalously Scattering Region (ASR), which scatters light almost isotropically with g = -0.04. In part due to the effects of Triton's clouds and haze, it is difficult to constrain the value of bar-theta, Hapke's macroscopic roughness parameter, precisely for Triton or to map differences in bar-theta among the different photometric terrains. However, our study shows that Triton must be relatively smooth, with bar-theta less than 15-20 degs and suggests that a value of 14 degs is appropriate. The differences in photometric characteristics lead to significantly different phase angle behavior for the various terrains. For example, a terrain (e.g., the ASR) that appears dark relative to another at low phase angles will reverse its contrast (become relatively brighter) at larger phase angles. The photometric parameters have been used to calculate hemispherical albedos for the units and to

  12. Kinetic detection of the end-point in titrations involving slow reactions Direct titration of polyhydroxy-compounds with periodate.

    PubMed

    Efstathiou, C E; Hadjiioannou, T P

    1983-03-01

    A new titration technique is described in which the end-point is determined by measuring the relative reaction rate of the titration reaction. This technique is adequate for rather slow reactions where conventional direct titrations are not applicable. The titrations are done automatically under microcomputer control. The efficiency of this technique is demonstrated with direct titrations of certain polyhydroxy-compounds with standard periodate solution. Ethylene glycol and propylene glycol (0.05-0.3 mmole), glycerol (0.06-0.17 mmole) and mannitol (0.01-0.03 mmole) were determined with average relative errors of 0.1-0.3%.

  13. System for clinical photometric stereo endoscopy

    NASA Astrophysics Data System (ADS)

    Durr, Nicholas J.; González, Germán.; Lim, Daryl; Traverso, Giovanni; Nishioka, Norman S.; Vakoc, Benjamin J.; Parot, Vicente

    2014-02-01

    Photometric stereo endoscopy is a technique that captures information about the high-spatial-frequency topography of the field of view simultaneously with a conventional color image. Here we describe a system that will enable photometric stereo endoscopy to be clinically evaluated in the large intestine of human patients. The clinical photometric stereo endoscopy system consists of a commercial gastroscope, a commercial video processor, an image capturing and processing unit, custom synchronization electronics, white light LEDs, a set of four fibers with diffusing tips, and an alignment cap. The custom pieces that come into contact with the patient are composed of biocompatible materials that can be sterilized before use. The components can then be assembled in the endoscopy suite before use. The resulting endoscope has the same outer diameter as a conventional colonoscope (14 mm), plugs into a commercial video processor, captures topography and color images at 15 Hz, and displays the conventional color image to the gastroenterologist in real-time. We show that this system can capture a color and topographical video in a tubular colon phantom, demonstrating robustness to complex geometries and motion. The reported system is suitable for in vivo evaluation of photometric stereo endoscopy in the human large intestine.

  14. Kohoutek, photometric photography experiment (S233)

    NASA Technical Reports Server (NTRS)

    Lundquist, C. A.; Craven, P. D.

    1981-01-01

    The final results of the Skylab 4 experiment S233, Kohoutek photometric photography experiment, which undertook a series of visible light photographs suitable for photometry and for a photographic history of Comet Kohoutek are described. The experiment concept, the data reduction method, and the results obtained are discussed.

  15. THE Pan-STARRS1 PHOTOMETRIC SYSTEM

    SciTech Connect

    Tonry, J. L.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Morgan, J. S.; Wainscoat, R. J.; Stubbs, C. W.; Shivvers, I. S.; Lykke, K. R.; Doherty, P.; Price, P. A.

    2012-05-10

    The Pan-STARRS1 survey is collecting multi-epoch, multi-color observations of the sky north of declination -30 Degree-Sign to unprecedented depths. These data are being photometrically and astrometrically calibrated and will serve as a reference for many other purposes. In this paper, we present our determination of the Pan-STARRS1 photometric system: g{sub P1}, r{sub P1}, i{sub P1}, z{sub P1}, y{sub P1}, and w{sub P1}. The Pan-STARRS1 photometric system is fundamentally based on the Hubble Space Telescope Calspec spectrophotometric observations, which in turn are fundamentally based on models of white dwarf atmospheres. We define the Pan-STARRS1 magnitude system and describe in detail our measurement of the system passbands, including both the instrumental sensitivity and atmospheric transmission functions. By-products, including transformations to other photometric systems, Galactic extinction, and stellar locus, are also provided. We close with a discussion of remaining systematic errors.

  16. Rapid retrovirus titration using competitive polymerase chain reaction.

    PubMed

    Tafuro, S; Zentilin, L; Falaschi, A; Giacca, M

    1996-08-01

    A quantitative polymerase chain reaction (PCR) procedure has been developed for rapid retrovirus titration. This procedure, which is based on the simultaneous amplification of the sample with known amounts of a competitor DNA fragment (competitive PCR), was used for the quantification of viral RNA genomes in retrovirus-producing cell clone supernatants and of proviral DNA molecules formed at 24 h after infection of different reference cell lines. The results obtained from the analysis of several samples indicated that proviral DNA quantification is in complete agreement with the number of selectable colonies in a standard colony assay. Conversely, the number of viral RNA genomes in the producer cell clone supernatants is a poor predictor of the actual efficiency of infection. Repeated competitive PCR experiments for provirus copy number determination at different times after transduction indicated that the number of proviral DNA molecules remains stable over time, suggesting stable integration into the host genome. The developed procedure is rapid and simple, is applicable to retroviral constructs not containing a selectable gene and can be used to directly measure the efficiency of infection of any target cell type, thus overcoming the problem of the dependency of retroviral titer determination on the rate of expression of a selectable gene and on the efficiency of colony formation of a reference cell line.

  17. Philosophy and updating of the asteroid photometric catalogue

    NASA Technical Reports Server (NTRS)

    Magnusson, Per; Barucci, M. Antonietta; Capria, M. T.; Dahlgren, Mats; Fulchignoni, Marcello; Lagerkvist, C. I.

    1992-01-01

    The Asteroid Photometric Catalogue now contains photometric lightcurves for 584 asteroids. We discuss some of the guiding principles behind it. This concerns both observers who offer input to it and users of the product.

  18. Asteroids (21) Lutetia: global and spatially resolved photometric properties

    NASA Astrophysics Data System (ADS)

    Faury, G.; Lamy, P.; Vernazza, P.; Jorda, L.; Toth, I.

    2011-10-01

    Asteroids (21) Lutetia has recently been visited by the Rosetta spacecraft of the European Space Agency and imaged by its Rosetta narrow (NAC) and wide (WAC) angle cameras. The accurate photometric analysis of the images requires utmost care due to several instrumental problems, the most severe and complex to handle being the presence of optical ghosts which result from multiple reflections on the two filters inserted in the optical beam and on the thick window which protects the CCD detector from cosmic ray impacts. These ghosts prominently appears as either slighlty defocused images offset from the primary images or large round or elliptical halos. The appearance, the location and the radiance of each individual ghost depends upon the optical configuration (selected filters) and on the image itself so that no general model can be proposed. Consequently, a case-by-case approach must be adopted which requires a long and tedious work where each ghost is individually parametrized according to its specific geometry (defocused offset image or halo) and iteratively fitted to the original image. The procedure has been successfully applied to all NAC and WAC images and works extremely well with residuals and sometime artifacts at insignificant levels. Both NAC and WAC have further been recalibrated using the most recent observations of stellar calibrators VEGA and the solar analog 16 Cyg B allowing to correct the quantum efficiency response of the two CCD and the throughput for all channels (i.e., filters). We will present results on the global photometric properties of (21) Lutetia, albedo, phase function and spectral reflectivity as well as spatially resolved properties based on a novel method developed in the space of the facets representing the three-dimensional shape of the body. This method successfully implemented in the cases of the nucleus of comet 9P/Tempel 2 and of asteroid (2867) Steins (Spjuth et al. 2011) has the advantage of automatically tracking the same

  19. CONDUCTIVITY TITRATION OF GELATIN SOLUTIONS WITH ACIDS.

    PubMed

    Hitchcock, D I

    1923-11-20

    Titrations have been made, by the conductivity method, of gelatin solutions with hydrochloric and sulphuric acids. The results indicate an end-point at about 8.6 cc. of N/10 acid per gm. of gelatin, or a combining weight of about 1,160. These results are in fair agreement with those previously obtained by the hydrogen electrode method. Better agreement between the two methods was found in the case of deaminized gelatin. The data are in accord with a purely chemical conception of the combination between protein and acid.

  20. Tracer monitored titrations: measurement of dissolved oxygen.

    PubMed

    Martz, Todd; Takeshita, Yuichiro; Rolph, Rebecca; Bresnahan, Philip

    2012-01-01

    The tracer monitored titration (TMT) technique is evaluated for measurement of dissolved oxygen. The TMT developed in this work uses a simple apparatus consisting of a low-precision pump for titrant delivery and an optical detector based on a white LED and two photodiodes with interference filters. It is shown that the classic Winkler method can be made free of routine volumetric and gravimetric measurements by application of TMT theory, which allows tracking the amounts of titrant and sample using a chemical tracer. The measurement precision of the prototype setup was 0.3% RSD.

  1. Modeling complexometric titrations of natural water samples.

    PubMed

    Hudson, Robert J M; Rue, Eden L; Bruland, Kenneth W

    2003-04-15

    Complexometric titrations are the primary source of metal speciation data for aquatic systems, yet their interpretation in waters containing humic and fulvic acids remains problematic. In particular, the accuracy of inferred ambient free metal ion concentrations and parameters quantifying metal complexation by natural ligands has been challenged because of the difficulties inherent in calibrating common analytical methods and in modeling the diverse array of ligands present. This work tests and applies a new method of modeling titration data that combines calibration of analytical sensitivity (S) and estimation of concentrations and stability constants for discrete natural ligand classes ([Li]T and Ki) into a single step using nonlinear regression and a new analytical solution to the one-metal/two-ligand equilibrium problem. When applied to jointly model data from multiple titrations conducted at different analytical windows, it yields accurate estimates of S, [Li]T, Ki, and [Cu2+] plus Monte Carlo-based estimates of the uncertainty in [Cu2+]. Jointly modeling titration data at low-and high-analytical windows leads to an efficient adaptation of the recently proposed "overload" approach to calibrating ACSV/CLE measurements. Application of the method to published data sets yields model results with greater accuracy and precision than originally obtained. The discrete ligand-class model is also re-parametrized, using humic and fulvic acids, L1 class (K1 = 10(13) M(-1)), and strong ligands (L(S)) with K(S) > K1 as "natural components". This approach suggests that Cu complexation in NW Mediterranean Sea water can be well represented as 0.8 +/- 0.3/0.2 mg humic equiv/L, 13 +/- 1 nM L1, and 2.5 +/- 0.1 nM L(S) with [CU]T = 3 nM. In coastal seawater from Narragansett Bay, RI, Cu speciation can be modeled as 0.6 +/- 0.1 mg humic equiv/L and 22 +/- 1 nM L1 or approximately 12 nM L1 and approximately 9 nM L(S), with [CU]T = 13 nM. In both waters, the large excess

  2. Photometric method for determination of acidity constants through integral spectra analysis.

    PubMed

    Zevatskiy, Yuriy Eduardovich; Ruzanov, Daniil Olegovich; Samoylov, Denis Vladimirovich

    2015-04-15

    An express method for determination of acidity constants of organic acids, based on the analysis of the integral transmittance vs. pH dependence is developed. The integral value is registered as a photocurrent of photometric device simultaneously with potentiometric titration. The proposed method allows to obtain pKa using only simple and low-cost instrumentation. The optical part of the experimental setup has been optimized through the exclusion of the monochromator device. Thus it only takes 10-15 min to obtain one pKa value with the absolute error of less than 0.15 pH units. Application limitations and reliability of the method have been tested for a series of organic acids of various nature.

  3. Photometric method for determination of acidity constants through integral spectra analysis

    NASA Astrophysics Data System (ADS)

    Zevatskiy, Yuriy Eduardovich; Ruzanov, Daniil Olegovich; Samoylov, Denis Vladimirovich

    2015-04-01

    An express method for determination of acidity constants of organic acids, based on the analysis of the integral transmittance vs. pH dependence is developed. The integral value is registered as a photocurrent of photometric device simultaneously with potentiometric titration. The proposed method allows to obtain pKa using only simple and low-cost instrumentation. The optical part of the experimental setup has been optimized through the exclusion of the monochromator device. Thus it only takes 10-15 min to obtain one pKa value with the absolute error of less than 0.15 pH units. Application limitations and reliability of the method have been tested for a series of organic acids of various nature.

  4. Bivoltametric titrations using electrodes with innovative geometry.

    PubMed

    Surmann, P; Peter, B; Stark, C

    1996-09-01

    Electrodes with different surface areas were investigated for the determination of reversible, quasireversible, irreversible or electroinactive substrates. Two kinds of electrodes were constructed, a helical electrode with a given asymmetry and a platinum array electrode with a variable area. These electrodes were applied for the cerimetry of ammonium iron(II) sulfate and for the bromatometry of various organic substances. The theoretically derived effects on the shape of the voltametric titration curve are verified experimentally. It is possible to sharpen one side of the peak and to broaden the other side, depending on the system and the side of the peak one is interested in. It is possible to improve the bivoltametric determination of hydroquinone, benzocaine and sulfaguanidine by bromatometry by the directed employment of electrodes of different areas. For the bromatometric determination of electrochemically irreversible substrates the use of the electrode geometries proposed is a way to obtain a sharp bend and a steep decrease of titration curves with low values of the constant current which is a basic requirement for the accuracy.

  5. Biochemical titration of glycogen in vitro.

    PubMed

    Pelletier, Joffrey; Bellot, Grégory; Pouysségur, Jacques; Mazure, Nathalie M

    2013-01-01

    Glycogen is the main energetic polymer of glucose in vertebrate animals and plays a crucial role in whole body metabolism as well as in cellular metabolism. Many methods to detect glycogen already exist but only a few are quantitative. We describe here a method using the Abcam Glycogen assay kit, which is based on specific degradation of glycogen to glucose by glucoamylase. Glucose is then specifically oxidized to a product that reacts with the OxiRed probe to produce fluorescence. Titration is accurate, sensitive and can be achieved on cell extracts or tissue sections. However, in contrast to other techniques, it does not give information about the distribution of glycogen in the cell. As an example of this technique, we describe here the titration of glycogen in two cell lines, Chinese hamster lung fibroblast CCL39 and human colon carcinoma LS174, incubated in normoxia (21% O2) versus hypoxia (1% O2). We hypothesized that hypoxia is a signal that prepares cells to synthesize and store glycogen in order to survive(1).

  6. Biochemical Titration of Glycogen In vitro

    PubMed Central

    Pelletier, Joffrey; Bellot, Grégory; Pouysségur, Jacques; Mazure, Nathalie M.

    2013-01-01

    Glycogen is the main energetic polymer of glucose in vertebrate animals and plays a crucial role in whole body metabolism as well as in cellular metabolism. Many methods to detect glycogen already exist but only a few are quantitative. We describe here a method using the Abcam Glycogen assay kit, which is based on specific degradation of glycogen to glucose by glucoamylase. Glucose is then specifically oxidized to a product that reacts with the OxiRed probe to produce fluorescence. Titration is accurate, sensitive and can be achieved on cell extracts or tissue sections. However, in contrast to other techniques, it does not give information about the distribution of glycogen in the cell. As an example of this technique, we describe here the titration of glycogen in two cell lines, Chinese hamster lung fibroblast CCL39 and human colon carcinoma LS174, incubated in normoxia (21% O2) versus hypoxia (1% O2). We hypothesized that hypoxia is a signal that prepares cells to synthesize and store glycogen in order to survive1. PMID:24300406

  7. Photometric study of the active binary star V1430 Aquilae

    NASA Astrophysics Data System (ADS)

    Erdem, A.; Sürgit, D.

    2006-05-01

    New BVR light curves and a photometric analysis of the eclipsing binary star V1430 Aql are presented. The light curves were obtained at the Çanakkale Onsekiz Mart University Observatory in 2004. The light curves are generally those of detached eclipsing binaries, but there are large asymmetries between maxima. New BVR light curves were analysed with an ILOT procedure. Light curve asymmetries of the system were explained in terms of large dark starspots on the primary component. The primary star shows a long-lived and quasi-poloidal spot distribution with active longitudes in opposite hemispheres. Absolute parameters of the system were derived. We also discuss the evolution of the system: the components are likely to be pre-main sequence stars, but a post-main sequence stage cannot be ruled out. More observations are needed to decide this point.

  8. Technical Note: How long can seawater oxygen samples be stored before titration?

    NASA Astrophysics Data System (ADS)

    Lankhorst, M.; Chavez, G.; Nam, S. H.; Send, U.

    2014-10-01

    The concentration of dissolved oxygen in seawater is routinely measured using a standardized titration method that involves analysis shortly after the water sample has been collected. However, none of the existing procedural documents are specific about how soon after collection the titration has to be done. Here, we report on a small number of samples where duplicates were collected and one batch was titrated within days after collection, while the other batch was stored for several weeks before titration. In addition, for a subset of the samples a third batch was taken that was stored like the others but with a particular chemical already added before storage. Comparison between the batches confirms that there is no significant difference between the ones that were stored and the ones that were analyzed sooner, indicating that a month-long storage period is acceptable. The implication of this is that such oxygen samples do not necessarily have to be analyzed while still on the ship; instead, it is possible to transport them ashore for analysis there.

  9. Developing a multipoint titration method with a variable dose implementation for anaerobic digestion monitoring.

    PubMed

    Salonen, K; Leisola, M; Eerikäinen, T

    2009-01-01

    Determination of metabolites from an anaerobic digester with an acid base titration is considered as superior method for many reasons. This paper describes a practical at line compatible multipoint titration method. The titration procedure was improved by speed and data quality. A simple and novel control algorithm for estimating a variable titrant dose was derived for this purpose. This non-linear PI-controller like algorithm does not require any preliminary information from sample. Performance of this controller is superior compared to traditional linear PI-controllers. In addition, simplification for presenting polyprotic acids as a sum of multiple monoprotic acids is introduced along with a mathematical error examination. A method for inclusion of the ionic strength effect with stepwise iteration is shown. The titration model is presented with matrix notations enabling simple computation of all concentration estimates. All methods and algorithms are illustrated in the experimental part. A linear correlation better than 0.999 was obtained for both acetate and phosphate used as model compounds with slopes of 0.98 and 1.00 and average standard deviations of 0.6% and 0.8%, respectively. Furthermore, insensitivity of the presented method for overlapping buffer capacity curves was shown.

  10. Astrophysical science with a spaceborne photometric telescope

    NASA Technical Reports Server (NTRS)

    Granados, Arno F. (Editor); Borucki, William J. (Editor)

    1994-01-01

    The FRESIP Project (FRequency of Earth-Sized Inner Planets) is currently under study at NASA Ames Research Center. The goal of FRESIP is the measurement of the frequency of Earth-sized extra-solar planets in inner orbits via the photometric signature of a transit event. This will be accomplished with a spaceborne telescope/photometer capable of photometric precision of two parts in 100,000 at a magnitude of m(sub v) = 12.5. To achieve the maximum scientific value from the FRESIP mission, an astrophysical science workshop was held at the SETI Institute in Mountain View, California, November 11-12, 1993. Workshop participants were invited as experts in their field of astrophysical research and discussed the astrophysical science that can be achieved within the context of the FRESIP mission.

  11. Photometric reverberation mapping of active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ramolla, M.; Pozo, F.; Westhues, C.; Haas, M.; Chini, R.; Steenbrugge, K.; Lemke, R.; Murphy, M.

    2014-12-01

    Photometric reverberation mapping is a novel method used to determine the size and geometry of the broad line region (BLR) in active galactic nuclei (AGN) as well as their host galaxy free luminosities. Establishing a tight luminosity - BLR-size relation may allow type-1 AGN to be used as cosmological distance probes. However, the quality of the results is most sensible to dense time sampling and continuity of the photometric lightcurves. This demands an observatory, with optimal environmental conditions, like the "Universitätssternwarte Bochum", located in the Atacama Desert in Chile. The massive amount of observations are controlled robotically, adapting observational schedules of the telescopes to the weather conditions. Here we present one of the first promising results of our studies.

  12. Automated titration method for use on blended asphalts

    DOEpatents

    Pauli, Adam T.; Robertson, Raymond E.; Branthaver, Jan F.; Schabron, John F.

    2012-08-07

    A system for determining parameters and compatibility of a substance such as an asphalt or other petroleum substance uses titration to highly accurately determine one or more flocculation occurrences and is especially applicable to the determination or use of Heithaus parameters and optimal mixing of various asphalt stocks. In a preferred embodiment, automated titration in an oxygen gas exclusive system and further using spectrophotometric analysis (2-8) of solution turbidity is presented. A reversible titration technique enabling in-situ titration measurement of various solution concentrations is also presented.

  13. Rapid Clozapine Titration in Patients with Treatment Refractory Schizophrenia.

    PubMed

    Poyraz, Cana Aksoy; Özdemir, Armağan; Sağlam, Nazife Gamze Usta; Turan, Şenol; Poyraz, Burç Çağrı; Tomruk, Nesrin; Duran, Alaattin

    2016-06-01

    The aim of this study is to evaluate the safety and effectiveness of rapid clozapine titration in patients with schizophrenia in hospital settings. We conducted a retrospective two-center cohort study to compare the safety and effectiveness of clozapine with different titration rates in treatment-refractory patients with schizophrenia. In the first center, clozapine was started at 25-50 mg followed by 50-100 mg as needed every 6 h on day 1, followed by increases of 50-100 mg/day. In the second center, titration was slower; clozapine initiated with 12.5-50 mg on day 1 followed by increases of 25-50 mg/day. The number of days between starting of clozapine until discharge was shorter in the rapid titration group (22.4 ± 8.72 vs 27.0 ± 10.5, p = 0.1). Number of days of total hospital stay were significantly shorter in the rapid titration group (29.6 ± 10.6 vs 41.2 ± 14.8, p = 0.002). Hypotension was more common in the rapid titration group and one patient had suspected myocarditis. Rapid clozapine titration appeared safe and effective. The length of stay following initiation of clozapine was shorter in the rapid-titration group, although this was not statistically significant. However starting clozapine earlier together with rapid titration has significantly shortened the length of hospital stay in patients with treatment refractory schizophrenia.

  14. A computer-controlled potentiometric/spectrophotometric titrator

    PubMed Central

    Stong, John D.

    1988-01-01

    A laboratory computer controlled potentiometric titrator interfaced to a diode array spectrophotometer is described. The titrator consists of widely used, commercially available components; therefore, major attention is given to modes of interconnection and software implementation in data format and system control. Replicate potentiometric titrations of glycines gave a relative standard deviation in titre of 1.035% and a relative standard deviation in pH of 0.745%. Replicate spectrophotometric titrations of bromophenol blue were analysed at three wavelengths to yield pKa= 3.898 ± 0.075 (1.9% rsd). Methods of data presentation and manipulation are presented. PMID:18925194

  15. Improving LSST Photometric Calibration with Gaia Data

    NASA Astrophysics Data System (ADS)

    Axelrod, Tim; Miller, Calder

    2014-12-01

    We consider the possibility that the Gaia mission can supply data which will improve the photometric calibration of LSST. After outlining the LSST calibration process and the information that will be available from Gaia, we explore two options for using Gaia data. The first is to use Gaia G-band photometry of selected stars, in conjunction with knowledge of the stellar parameters Teff, log g, and AV, and in some cases Z, to create photometric standards in the LSST u, g, r, i, z, and y bands. We consider both main sequence (MS) stars and DA white dwarfs (WD). The accuracies of the resulting standard magnitudes from MS stars are found to be insufficient to satisfy LSST requirements using Gaia data alone, but with the potential to do so when supplemented with ground-based spectroscopy. The accuracies of the WD derived standards are generally adequate, but also require ground-based spectroscopy. The second option is combine the LSST bandpasses into a synthetic Gaia G band, which is a close approximation to the real Gaia G band. This allows synthetic Gaia G photometry to be directly compared with actual Gaia G photometry at a level of accuracy which is useful for both verifying and improving LSST photometric calibration.

  16. Can Selforganizing Maps Accurately Predict Photometric Redshifts?

    NASA Technical Reports Server (NTRS)

    Way, Michael J.; Klose, Christian

    2012-01-01

    We present an unsupervised machine-learning approach that can be employed for estimating photometric redshifts. The proposed method is based on a vector quantization called the self-organizing-map (SOM) approach. A variety of photometrically derived input values were utilized from the Sloan Digital Sky Survey's main galaxy sample, luminous red galaxy, and quasar samples, along with the PHAT0 data set from the Photo-z Accuracy Testing project. Regression results obtained with this new approach were evaluated in terms of root-mean-square error (RMSE) to estimate the accuracy of the photometric redshift estimates. The results demonstrate competitive RMSE and outlier percentages when compared with several other popular approaches, such as artificial neural networks and Gaussian process regression. SOM RMSE results (using delta(z) = z(sub phot) - z(sub spec)) are 0.023 for the main galaxy sample, 0.027 for the luminous red galaxy sample, 0.418 for quasars, and 0.022 for PHAT0 synthetic data. The results demonstrate that there are nonunique solutions for estimating SOM RMSEs. Further research is needed in order to find more robust estimation techniques using SOMs, but the results herein are a positive indication of their capabilities when compared with other well-known methods

  17. The Sloan Digital Sky Survey Photometric Camera

    SciTech Connect

    Gunn, J.E.; Carr, M.; Rockosi, C.; Sekiguchi, M.; Berry, K.; Elms, B.; de Haas, E.; Ivezic, Z.; Knapp, G.; Lupton, R.; Pauls, G.; Simcoe, R.; Hirsch, R.; Sanford, D.; Wang, S.; York, D.; Harris, F.; Annis, J.; Bartozek, L.; Boroski, W.; Bakken, J.; Haldeman, M.; Kent, S.; Holm, S.; Holmgren, D.; Petravick, D.; Prosapio, A.; Rechenmacher, R.; Doi, M.; Fukugita, M.; Shimasaku, K.; Okada, N.; Hull, C.; Siegmund, W.; Mannery, E.; Blouke, M.; Heidtman, D.; Schneider, D.; Lucinio, R.; and others

    1998-12-01

    We have constructed a large-format mosaic CCD camera for the Sloan Digital Sky Survey. The camera consists of two arrays, a photometric array that uses 30 2048 {times} 2048 SITe/Tektronix CCDs (24 {mu}m pixels) with an effective imaging area of 720 cm{sup 2} and an astrometric array that uses 24 400 {times} 2048 CCDs with the same pixel size, which will allow us to tie bright astrometric standard stars to the objects imaged in the photometric camera. The instrument will be used to carry out photometry essentially simultaneously in five color bands spanning the range accessible to silicon detectors on the ground in the time-delay{endash}and{endash}integrate (TDI) scanning mode. The photometric detectors are arrayed in the focal plane in six columns of five chips each such that two scans cover a filled stripe 2&arcdeg;5 wide. This paper presents engineering and technical details of the camera. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}

  18. The acid-base titration of montmorillonite

    NASA Astrophysics Data System (ADS)

    Bourg, I. C.; Sposito, G.; Bourg, A. C.

    2003-12-01

    Proton binding to clay minerals plays an important role in the chemical reactivity of soils (e.g., acidification, retention of nutrients or pollutants). If should also affect the performance of clay barriers for waste disposal. The surface acidity of clay minerals is commonly modelled empirically by assuming generic amphoteric surface sites (>SOH) on a flat surface, with fitted site densities and acidity constant. Current advances in experimental methods (notably spectroscopy) are rapidly improving our understanding of the structure and reactivity of the surface of clay minerals (arrangement of the particles, nature of the reactive surface sites, adsorption mechanisms). These developments are motivated by the difficulty of modelling the surface chemistry of mineral surfaces at the macro-scale (e.g., adsorption or titration) without a detailed (molecular-scale) picture of the mechanisms, and should be progressively incorporated into surface complexation models. In this view, we have combined recent estimates of montmorillonite surface properties (surface site density and structure, edge surface area, surface electrostatic potential) with surface site acidities obtained from the titration of alpha-Al2O3 and SiO2, and a novel method of accounting for the unknown initial net proton surface charge of the solid. The model predictions were compared to experimental titrations of SWy-1 montmorillonite and purified MX-80 bentonite in 0.1-0.5 mol/L NaClO4 and 0.005-0.5 mol/L NaNO3 background electrolytes, respectively. Most of the experimental data were appropriately described by the model after we adjusted a single parameter (silanol sites on the surface of montmorillonite were made to be slightly more acidic than those of silica). At low ionic strength and acidic pH the model underestimated the buffering capacity of the montmorillonite, perhaps due to clay swelling or to the interlayer adsorption of dissolved aluminum. The agreement between our model and the experimental

  19. 3-D Surface Visualization of pH Titration "Topos": Equivalence Point Cliffs, Dilution Ramps, and Buffer Plateaus

    ERIC Educational Resources Information Center

    Smith, Garon C.; Hossain, Md Mainul; MacCarthy, Patrick

    2014-01-01

    3-D topographic surfaces ("topos") can be generated to visualize how pH behaves during titration and dilution procedures. The surfaces are constructed by plotting computed pH values above a composition grid with volume of base added in one direction and overall system dilution on the other. What emerge are surface features that…

  20. Automated analysis of calorimetric demicellization titrations.

    PubMed

    Textor, Martin; Keller, Sandro

    2015-09-15

    Determination of the critical micellar concentration of surfactants and of the heat of demicellization by means of isothermal titration calorimetry usually involves either calculation of the first derivative of the heat of demicellization with respect to surfactant concentration or application of a generic sigmoidal fit to the demicellization isotherm. Here, we show that a combination of both approaches provides an unbiased and reproducible data analysis strategy without the need for user input other than the calorimetric data proper. The approach is explained and exemplified using demicellization isotherms of the fluorinated surfactant F6OPC (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-n-octylphosphocholine) and the zwitterionic detergent CHAPSO (3-([3-cholamidopropyl]dimethylammonio)-2-hydroxy-1-propanesulfonate).

  1. Production and titration of lentiviral vectors.

    PubMed

    Salmon, Patrick; Trono, Didier

    2006-11-01

    Lentiviral vectors have emerged over the last decade as powerful, reliable and safe tools for stable gene transfer in a wide variety of mammalian cells. Unlike other vectors derived from oncoretroviruses, they allow for stable gene delivery into most nondividing primary cells, including neurons. This is why LVs are becoming the most useful and promising tools in the field of neuroscience, not only for research, but also for future gene and cell therapy approaches. Lentivectors (LVs) derived from HIV-1 have gradually evolved to display many desirable features aimed at increasing both their safety and their versatility. These latest designs are reviewed in this unit. This unit also describes protocols for production and titration of LVs that can be implemented in a research laboratory setting, with an emphasis on standardization to improve transposability of results between laboratories.

  2. Isothermal Titration Calorimetry to Characterize Enzymatic Reactions.

    PubMed

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2016-01-01

    Isothermal titration calorimetry (ITC) is a technique that measures the heat released or absorbed during a chemical reaction as an intrinsic probe to characterize any chemical process that involves heat changes spontaneously occurring during the reaction. The general features of this method to determine the kinetic and thermodynamic parameters of enzymatic reactions (kcat, KM, ΔH) are described and discussed here together with some detailed applications to specific cases. ITC does not require any modification or labeling of the system under analysis, can be performed in solution, and needs only small amounts of enzyme. These properties make ITC an invaluable, powerful, and unique tool to extend the knowledge of enzyme kinetics to drug discovery.

  3. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    PubMed

    Werber, Liora; Preiss, Laura C; Landfester, Katharina; Muñoz-Espí, Rafael; Mastai, Yitzhak

    2015-09-01

    Chiral polymeric nanoparticles are of prime importance, mainly due to their enantioselective potential, for many applications such as catalysis and chiral separation in chromatography. In this article we report on the preparation of chiral polymeric nanoparticles by miniemulsion polymerization. In addition, we describe the use of isothermal titration calorimetry (ITC) to measure the chiral interactions and the energetics of the adsorption of enantiomers from aqueous solutions onto chiral polymeric nanoparticles. The characterization of chirality in nano-systems is a very challenging task; here, we demonstrate that ITC can be used to accurately determine the thermodynamic parameters associated with the chiral interactions of nanoparticles. The use of ITC to measure the energetics of chiral interactions and recognition at the surfaces of chiral nanoparticles can be applied to other nanoscale chiral systems and can provide further insight into the chiral discrimination processes of nanomaterials.

  4. 40 CFR Appendix F to Part 50 - Measurement Principle and Calibration Procedure for the Measurement of Nitrogen Dioxide in the...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 1. Alternative A—Gas phase titration (GPT) of an NO standard with O3. Major equipment required... titration. A procedure for generating zero air is given in reference 13. 1.4 Dynamic parameter specification... Dioxide, and Ozone Analyzers by Gas Phase Titration,” EPA-R2-73-246, March 1974. 9. J. A. Hodgeson, R....

  5. 40 CFR Appendix F to Part 50 - Measurement Principle and Calibration Procedure for the Measurement of Nitrogen Dioxide in the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 1. Alternative A—Gas phase titration (GPT) of an NO standard with O3. Major equipment required... titration. A procedure for generating zero air is given in reference 13. 1.4 Dynamic parameter specification... Dioxide, and Ozone Analyzers by Gas Phase Titration,” EPA-R2-73-246, March 1974. 9. J. A. Hodgeson, R....

  6. 40 CFR Appendix F to Part 50 - Measurement Principle and Calibration Procedure for the Measurement of Nitrogen Dioxide in the...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 1. Alternative A—Gas phase titration (GPT) of an NO standard with O3. Major equipment required... titration. A procedure for generating zero air is given in reference 13. 1.4 Dynamic parameter specification... Dioxide, and Ozone Analyzers by Gas Phase Titration,” EPA-R2-73-246, March 1974. 9. J. A. Hodgeson, R....

  7. 40 CFR Appendix F to Part 50 - Measurement Principle and Calibration Procedure for the Measurement of Nitrogen Dioxide in the...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 1. Alternative A—Gas phase titration (GPT) of an NO standard with O3. Major equipment required... titration. A procedure for generating zero air is given in reference 13. 1.4 Dynamic parameter specification... Dioxide, and Ozone Analyzers by Gas Phase Titration,” EPA-R2-73-246, March 1974. 9. J. A. Hodgeson, R....

  8. Hydrogen-ion titrations of amino acids and proteins in solutions containing concentrated electrolyte

    SciTech Connect

    Fergg, F.; Kuehner, D.E.; Blanch, H.W.; Prausnitz, J.M.

    1994-12-01

    This report describes a first attempt to quantify the net charge as a function of solution pH for lysozyme and {alpha}-chymotrypsin at 0.1 M, 1.0 M and 3.0 M ionic strength, (IS). The calculations are based on the residue (titratable group) pK{sub a}`s in the amino-acid sequence of the protein. To determine these pK{sub a}`s, a simple theory was used which assumes that the pK{sub a}`s are independent from each other in the protein and are equal to their pK{sub a} values in free amino-acid solution (Independent-Site Theory, IST). Residue pK{sub a}`s were obtained from amino-acid hydrogen-ion titrations at three different KCl concentrations corresponding to 0.1M, 1.0M and 3.0M ionic strength. After construction of a suitable apparatus, the experimental procedure and data reduction were computerized to perform a large number of titrations. Most measured pK{sub a}`s showed high reproducibility (the difference of pK{sub a} values observed between two experiments was less than 0.05). For IS = 0.1M, observed pK{sub a}`s agreed with literature values to within a few hundredths of a pH unit. Furthermore, the ionic-strength dependence of the pK{sub a}`s followed the trends reported in the literature, viz. pK{sub a} values decrease with increasing ionic strength until they reach a minimum at about IS = 0.5M. At still higher IS, pK{sub a}`s increase as the ionic strength rises to 3M. The known pK{sub a}`s of all titratable groups in a protein were used with the IST to give a first approximation of how the protein net charge varies with pH at high ionic strength. A comparison of the titration curves based on the IST with experimental lysozyme and {alpha}-chymotrypsin titration data indicates acceptable agreement at IS = 0.1M. However, comparison of measured and calculated titration curves at IS = 1M and IS = 3M indicates only quantitative agreement.

  9. Continuous on-line feedback based flow titrations. Complexometric titrations of calcium and magnesium.

    PubMed

    Jo, Kyoo Dong; Dasgupta, Purnendu K

    2003-05-28

    The methodology of continuous feedback-based flow titrations and the principle of compensating errors [Anal. Chem. 72 (2000) 4713; Anal. Chim. Acta 435 (2001) 289] were applied to the determination of calcium and magnesium ions with EDTA. The flow of the titrant, EDTA, varied linearly in response to a controller output voltage while the total flow (F(T), the sum of the metal ion sample flow and the titrant flow) was held constant. The sample was pre-doped with a metal ion indicator; the status of the indicator color in the mixed stream was monitored by an optical detector and was used for governing the controller output as well as for interpreting the results of the titrations. The titrant flow initially ramped upward linearly. As a change in the color corresponding to the equivalence point was sensed by the detector, the controller output (instantaneous value V(H)) reversed its ramp direction, thus decreasing the titrant flow linearly at the same ramp rate. When the predefined absorbance corresponding to the equivalence point was sensed again, the controller voltage (instantaneous value V(L)) was ramped in reverse once more, going upward. Because of the lag time between a change in the controller output and its effect being sensed by the detector, the controller voltage corresponding to the actual equivalence point was the average of V(H) and V(L). Continuous sensor-governed operation of the controller resulted in a triangular waveform. The mean of this waveform during any cycle gives the equivalence point controller voltage V(E). This principle allowed true titrations with good reproducibility (0.2-0.7% R.S.D.) and throughput (33-42 s per titration).

  10. Differential Binding Models for Direct and Reverse Isothermal Titration Calorimetry.

    PubMed

    Herrera, Isaac; Winnik, Mitchell A

    2016-03-10

    Isothermal titration calorimetry (ITC) is a technique to measure the stoichiometry and thermodynamics from binding experiments. Identifying an appropriate mathematical model to evaluate titration curves of receptors with multiple sites is challenging, particularly when the stoichiometry or binding mechanism is not available. In a recent theoretical study, we presented a differential binding model (DBM) to study calorimetry titrations independently of the interaction among the binding sites (Herrera, I.; Winnik, M. A. J. Phys. Chem. B 2013, 117, 8659-8672). Here, we build upon our DBM and show its practical application to evaluate calorimetry titrations of receptors with multiple sites independently of the titration direction. Specifically, we present a set of ordinary differential equations (ODEs) with the general form d[S]/dV that can be integrated numerically to calculate the equilibrium concentrations of free and bound species S at every injection step and, subsequently, to evaluate the volume-normalized heat signal (δQ(V) = δq/dV) of direct and reverse calorimetry titrations. Additionally, we identify factors that influence the shape of the titration curve and can be used to optimize the initial concentrations of titrant and analyte. We demonstrate the flexibility of our updated DBM by applying these differentials and a global regression analysis to direct and reverse calorimetric titrations of gadolinium ions with multidentate ligands of increasing denticity, namely, diglycolic acid (DGA), citric acid (CIT), and nitrilotriacetic acid (NTA), and use statistical tests to validate the stoichiometries for the metal-ligand pairs studied.

  11. Students' integration of multiple representations in a titration experiment

    NASA Astrophysics Data System (ADS)

    Kunze, Nicole M.

    A complete understanding of a chemical concept is dependent upon a student's ability to understand the microscopic or particulate nature of the phenomenon and integrate the microscopic, symbolic, and macroscopic representations of the phenomenon. Acid-base chemistry is a general chemistry topic requiring students to understand the topics of chemical reactions, solutions, and equilibrium presented earlier in the course. In this study, twenty-five student volunteers from a second semester general chemistry course completed two interviews. The first interview was completed prior to any classroom instruction on acids and bases. The second interview took place after classroom instruction, a prelab activity consisting of a titration calculation worksheet, a titration computer simulation, or a microscopic level animation of a titration, and two microcomputer-based laboratory (MBL) titration experiments. During the interviews, participants were asked to define and describe acid-base concepts and in the second interview they also drew the microscopic representations of four stages in an acid-base titration. An analysis of the data showed that participants had integrated the three representations of an acid-base titration to varying degrees. While some participants showed complete understanding of acids, bases, titrations, and solution chemistry, other participants showed several alternative conceptions concerning strong acid and base dissociation, the formation of titration products, and the dissociation of soluble salts. Before instruction, participants' definitions of acid, base, and pH were brief and consisted of descriptive terms. After instruction, the definitions were more scientific and reflected the definitions presented during classroom instruction.

  12. Microscale pH Titrations Using an Automatic Pipet.

    ERIC Educational Resources Information Center

    Flint, Edward B.; Kortz, Carrie L.; Taylor, Max A.

    2002-01-01

    Presents a microscale pH titration technique that utilizes an automatic pipet. A small aliquot (1-5 mL) of the analyte solution is titrated with repeated additions of titrant, and the pH is determined after each delivery. The equivalence point is determined graphically by either the second derivative method or a Gran plot. The pipet can be…

  13. Potentiometric Acid-Base Titrations with Activated Graphite Electrodes

    NASA Astrophysics Data System (ADS)

    Riyazuddin, P.; Devika, D.

    1997-10-01

    Dry cell graphite (DCG) electrodes activated with potassium permanganate are employed as potentiometric indicator electrodes for acid-base titrations. Special attention is given to an indicator probe comprising activated DCG-non-activiated DCG electrode couple. This combination also proves suitable for the titration of strong or weak acids.

  14. A Closer Look at Acid-Base Olfactory Titrations

    ERIC Educational Resources Information Center

    Neppel, Kerry; Oliver-Hoyo, Maria T.; Queen, Connie; Reed, Nicole

    2005-01-01

    Olfactory titrations using raw onions and eugenol as acid-base indicators are reported. An in-depth investigation on olfactory titrations is presented to include requirements for potential olfactory indicators and protocols for using garlic, onions, and vanillin as acid-base olfactory indicators are tested.

  15. Quantitative Analysis of Sulfate in Water by Indirect EDTA Titration

    ERIC Educational Resources Information Center

    Belle-Oudry, Deirdre

    2008-01-01

    The determination of sulfate concentration in water by indirect EDTA titration is an instructive experiment that is easily implemented in an analytical chemistry laboratory course. A water sample is treated with excess barium chloride to precipitate sulfate ions as BaSO[subscript 4](s). The unprecipitated barium ions are then titrated with EDTA.…

  16. A novel view of pH titration in biomolecules.

    PubMed

    Onufriev, A; Case, D A; Ullmann, G M

    2001-03-27

    When individual titratable sites in a molecule interact with each other, their pH titration can be considerably more complex than that of an independent site described by the classical Henderson-Hasselbalch equation. We propose a novel framework that decomposes any complex titration behavior into simple standard components. The approach maps the set of N interacting sites in the molecule onto a set of N independent, noninteracting quasi-sites, each characterized by a pK'(a) value. The titration curve of an individual site in the molecule is a weighted sum of Henderson-Hasselbalch curves corresponding to the quasi-sites. The total protonation curve is the unweighted sum of these Henderson-Hasselbalch curves. We show that pK'(a) values correspond to deprotonation constants available from methods that can be used to assess total proton uptake or release, and establish their connection to protonation curves of individual residues obtained by NMR or infrared spectroscopy. The new framework is tested on a small molecule diethylenetriaminepentaacetate (DTPA) exhibiting nonmonotonic titration curves, where it gives an excellent fit to experimental data. We demonstrate that the titration curve of a site in a group of interacting sites can be accurately reconstructed, if titration curves of the other sites are known. The application of the new framework to the protein rubredoxin demonstrates its usefulness in calculating and interpreting complicated titration curves.

  17. New method for titration of virus infectivity by immunostaining.

    PubMed

    Usuba, O; Schulman, J L; Deatly, A M; Bona, C A; Moran, T M

    1990-01-01

    We have developed a new method for titration of viruses utilizing automated microtiter technology. Compared to existing methods such as plaque assay or hemagglutination titration of influenza virus, the new method offers distinct advantages in terms of time and effort. In addition because multiple replicates can easily be employed accuracy can be increased.

  18. Characterization of binding interactions by isothermal titration calorimetry.

    PubMed

    Doyle

    1997-02-01

    Isothermal titration calorimetry is a high-accuracy method for measuring binding affinities. Titration calorimetry is a universal method that has broad impact throughout biotechnology. In recent years, microcalorimeters that are capable of characterizing binding interactions of biological macromolecules have become commercially available. Results from these studies are providing new insight into the molecular nature of macromolecular interactions.

  19. Semi-supervised learning for photometric supernova classification

    NASA Astrophysics Data System (ADS)

    Richards, Joseph W.; Homrighausen, Darren; Freeman, Peter E.; Schafer, Chad M.; Poznanski, Dovi

    2012-01-01

    We present a semi-supervised method for photometric supernova typing. Our approach is to first use the non-linear dimension reduction technique diffusion map to detect structure in a data base of supernova light curves and subsequently employ random forest classification on a spectroscopically confirmed training set to learn a model that can predict the type of each newly observed supernova. We demonstrate that this is an effective method for supernova typing. As supernova numbers increase, our semi-supervised method efficiently utilizes this information to improve classification, a property not enjoyed by template-based methods. Applied to supernova data simulated by Kessler et al. to mimic those of the Dark Energy Survey, our methods achieve (cross-validated) 95 per cent Type Ia purity and 87 per cent Type Ia efficiency on the spectroscopic sample, but only 50 per cent Type Ia purity and 50 per cent efficiency on the photometric sample due to their spectroscopic follow-up strategy. To improve the performance on the photometric sample, we search for better spectroscopic follow-up procedures by studying the sensitivity of our machine-learned supernova classification on the specific strategy used to obtain training sets. With a fixed amount of spectroscopic follow-up time, we find that, despite collecting data on a smaller number of supernovae, deeper magnitude-limited spectroscopic surveys are better for producing training sets. For supernova Ia (II-P) typing, we obtain a 44 per cent (1 per cent) increase in purity to 72 per cent (87 per cent) and 30 per cent (162 per cent) increase in efficiency to 65 per cent (84 per cent) of the sample using a 25th (24.5th) magnitude-limited survey instead of the shallower spectroscopic sample used in the original simulations. When redshift information is available, we incorporate it into our analysis using a novel method of altering the diffusion map representation of the supernovae. Incorporating host redshifts leads to a 5

  20. Analysis of variance in determinations of equivalence volume and of the ionic product of water in potentiometric titrations.

    PubMed

    Braibanti, A; Bruschi, C; Fisicaro, E; Pasquali, M

    1986-06-01

    expected instrumental noise, whereas the titrations in nitrate medium had a high noise level and even the determination of VEM was less certain. Procedures are also proposed for obtaining reference sets of data and checking the conformity of the solutions and apparatus to the chosen reference.

  1. Factors affecting the growth and titration by immunofluorescence of simian foamy virus.

    PubMed

    Gould, E A; Hartley, J

    1979-01-01

    This paper presents some observations concerned with the growth of simian foamy virus and some modifications which should be introduced to the fluorescence assay of foamy virus. The modified procedure is the most sensitive method described for the titration of foamy virus. Examination of the optimal conditions for the growth and titration by fluorescence assay of simian foamy virus showed that the virus was particularly sensitive to changes in virus and cell concentration. At the low cell concentrations employed previously a "saturation-type" response was obtained with high titre virus and virus adsorption efficiency was decreased as input virus was diluted. Maximum virus production was obtained with high cell concentrations at input multiplicities of 5 and 10. At high multiplicities of infection more than 90 per cent of the cells adsorbed virus but only 45 per cent became infected, this appeared to be related to cell DNA synthesis.

  2. Asteroid taxonomic signatures from photometric phase curves

    NASA Astrophysics Data System (ADS)

    Oszkiewicz, Dagmara Anna; Bowell, Edward; Wasserman, L. H.; Muinonen, Karri; Penttilä, Antti; Pieniluoma, Tuomo; Trilling, David E.; Thomas, Cristina A.

    2012-05-01

    We explore the correlation between an asteroid's taxonomy and photometric phase curve using the H, G12 photometric phase function, with the shape of the phase function described by the single parameter G12. We explore the usability of G12 in taxonomic classification for individual objects, asteroid families, and dynamical groups. We conclude that the mean values of G12 for the considered taxonomic complexes are statistically different, and also discuss the overall shape of the G12 distribution for each taxonomic complex. Based on the values of G12 for about half a million asteroids, we compute the probabilities of C, S, and X complex membership for each asteroid. For an individual asteroid, these probabilities are rather evenly distributed over all of the complexes, thus preventing meaningful classification. We then present and discuss the G12 distributions for asteroid families, and predict the taxonomic complex preponderance for asteroid families given the distribution of G12 in each family. For certain asteroid families, the probabilistic prediction of taxonomic complex preponderance can clearly be made. In particular, the C complex preponderant families are the easiest to detect, the Dora and Themis families being prime examples of such families. We continue by presenting the G12-based distribution of taxonomic complexes throughout the main asteroid belt in the proper element phase space. The Nysa-Polana family shows two distinct regions in the proper element space with different G12 values dominating in each region. We conclude that the G12-based probabilistic distribution of taxonomic complexes through the main belt agrees with the general view of C complex asteroid proportion increasing towards the outer belt. We conclude that the G12 photometric parameter cannot be used in determining taxonomic complex for individual asteroids, but it can be utilized in the statistical treatment of asteroid families and different regions of the main asteroid belt.

  3. The Definitive Johnson Kron-Cousins UBVRI Photometric System

    NASA Astrophysics Data System (ADS)

    Landolt, Arlo U.; Clem, James L.

    2015-08-01

    The defining characteristics and a brief history of the Johnson Kron-Cousins UBVRI photometric system will be reviewed, and recent observational efforts to extend the UBVRI standard star network, both in magnitude and sky coverage, presented. The current incarnation of this network now comprises more than 50,000 photometric standards distributed around the sky in three declination zones centered on -50 degrees, the celestial equator, and +50 degrees. The majority of these standards encompass the magnitude range of ~9 < V <~ 22, and the color index range of ~ -0.3 < B-V <~ +2. The standard error of the mean in the photometry is less than 0.005 magnitudes in BVRI and 0.015 magn. in U. Relations have been developed to permit conversion between the UBVRI and SDSS ugriz photometric systems, thereby enhancing the versatility of both photometric systems. Several uses of the UBVRI photometric system, and its synergy with other photometric systems, will be noted.

  4. Photometric normalization of LROC WAC images

    NASA Astrophysics Data System (ADS)

    Sato, H.; Boyd, A. K.; Denevi, B. W.; Robinson, M. S.; Hapke, B. W.; McEwen, A. S.; Humm, D. C.; LROC Science Operations Team

    2011-12-01

    Monthly global Lunar Reconnaissance Orbiter (LRO) Wide Angle Camera (WAC) observations of the Moon, acquired with varying emission and incidence angles, enable the precise derivation of spatially resolved Hapke photometric parameters [1]. The WAC global mosaics are stacked in a time series to enable phase curve fitting using a tile-by-tile method, with a wide range of phase angle in each tile. Tile-by-tile calculations provide photometric parameters for each tile (currently 1° by 1° from 80° to -80° latitude), resulting in resolved near-global photometric parameter maps (w, xi, Bco, and hc)[2]. Incidence, emission, and phase angles are computed using a new WAC stereometric digital terrain model (100 m/pixel)[3]. In the tile-by-tile method, we obtain low phase observations only near the equator resulting in an inability to accurately estimate Bco at higher latitudes (Hapke parameter controls the y-intercept of phase curve). We interpolated Bco poleward of +/- 5° latitudes, using a negative correlation between w and Bco observed in the equator +/- 5° latitudes. This interpolation method can decrease one free parameter, resulting in short calculation time and much less failed tiles. The normalized image using this parameter map shows almost no tile boundary, which shows that the tile-by-tile method works well. After the tile-by-tile method was applied with twenty months of data over a full range of beta angle, we observed an I/F offset with time. This offset results in reflectance differences at month-to-month boundaries in a global mosaic constructed from sequences acquired over different months (constructed to minimize incidence angle differences as a function of latitude). After significant tests of any possible parameters controlling the residual I/F value, incidence angle was revealed to be a dominant factor, indicating that the photometry model may not completely accounting for incidence angle. The main function dealing with incidence angle is the Lommel

  5. Photometric functions for photoclinometry and other applications

    NASA Technical Reports Server (NTRS)

    Mcewen, Alfred S.

    1991-01-01

    The simpler Minnaert and lunar-Lambert functions, which are needed to reduce the number of unknown parameters in photoclinometry, are presently given least-squares fits to the brightness profiles across a disk, or 'limb darkening', described by Hapke's photometric function. The variation of limb darkening with single-scattering albedo and the particle-phase function's asymmetry factor are reduced of eliminated when the Hapke parameters are in the range representative of most planetary surfaces, thereby simplifying the problem of photoclinometry across terrains with variable surface materials.

  6. Revised photometric elements of eight eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Mezzetti, M.; Predolin, F.; Giuricin, G.; Mardirossian, F.

    1980-10-01

    Photoelectric lightcurves of eight eclipsing binaries, known as detached systems, have been reanalysed by means of Wood's model in order to obtain homogeneous photometric elements. All binaries are confirmed to be detached. TU Cam, CW CMa, YZ Cas, CW Eri, CO Lac and EE Peg appear to be normal main-sequence (or near main-sequence) detached systems, but only the absolute elements of CO Lac are well-known. The detached binaries EK Cep and IQ Per are shown to be anomalous.

  7. Photometric solutions of some contact ASAS binaries

    NASA Astrophysics Data System (ADS)

    Gezer, İ.; Bozkurt, Z.

    2016-04-01

    We present the first light curve solution of 6 contact binary systems which are chosen from the ASAS catalog. The photometric elements and the estimated absolute parameters of all systems are obtained with the light curve analyses. We calculated the values of degree of contact for the systems. The location of the targets on the Hertzsprung-Russell diagram and the mass-radius plane is compared to the other well-known contact binaries and the evolutionary status of the systems are also discussed.

  8. SCREEN photometric property detection system based on area CCD

    NASA Astrophysics Data System (ADS)

    Yan, Fu-cai; Ye, Wei; Xu, Yu; Wang, Chao; Zhang, Yu-wei

    2011-08-01

    The photometric property detection of screen display is crucial for screen display quality test. Traditional photometry detection technologies were based on photoelectric sensors such as silicon photocell, photo-electric multiplier and CdS, which can detect only some isolated points. To break the limitation of randomness, incompleteness and detection accuracy in current technologies, we designed a screen photometric detection system based on area CCD. The system consists of photometric image sensor, photometric image acquisition hardware and photometric image analyzing software. The photometric image sensor, which adopts optical lens, optical filters and area CCD, adapts its spectrum response property to fit the spectrum luminous efficiency curve V (λ) by adjusting the thickness and quantity of appropriate optical filters. photometric image acquisition hardware adopts the DSP as a core processor to drive the area CCD, to sample, acquire , process and save the image from image sensor, to transmit the image to computer. For real-time performance of transmitting, the hardware system adopts the transmission protocol of USB2.0. The uploaded image will be processed by photometric image analyzing software, and then displayed in real time with detection results. The screen photometric detection technology based on area CCD can detect specifications of the whole screen such as luminance, contrast, onoff ratio and uniformity, breaks the limitation of randomness and incompleteness in current detection technology, exactly and fully reflects the integrated display quality of the whole screen. According to the test results, the accuracy of this system has reached the accuracy level one in China.

  9. Titration of gold nanoparticles in phase extraction.

    PubMed

    Cheng, Han-Wen; Schadt, Mark J; Zhong, Chuan-Jian

    2015-12-01

    In the organic-aqueous phase transfer process of gold nanoparticles, there are two types of distinctive interfaces involving hydrophilic and hydrophobic ligands, the understanding of which is important for the design of functional nanomaterials for analytical/bioanalytical applications and the control over the nanoparticles' nanoactivity and nanotoxicity in different phases. This report describes new findings of an investigation of the quantitative aspect of ligand ion pairing at the capping monolayer structure that drives the phase extraction of gold nanoparticles. Alkanethiolate-capped gold nanoparticles of 8 nm diameter with high size monodispersity (RSD ∼ 5%) were first derivatized by a ligand place exchange reaction with 11-mercaptoundecanoic acid to form a mixed monolayer shell consisting of both hydrophobic (-CH3) and hydrophilic (-COOH) groups. It was followed by quantitative titration of the resulting nanoparticles with a cationic species (-NR4(+)) in a toluene phase, yielding ion pairing of -NR4(+) and -COO(-) on part of the capping monolayer. Analysis of the phase extraction allowed a quantitative determination of the percentage of ion pairing and structural changes in the capping monolayer on the nanoparticles. The results, along with morphological characterization, are discussed in terms of the interfacial structural changes and their implications on the rational design of surface-functionalized nanoparticles and fine tuning of the interfacial reactivity. PMID:26523548

  10. Titration of gold nanoparticles in phase extraction.

    PubMed

    Cheng, Han-Wen; Schadt, Mark J; Zhong, Chuan-Jian

    2015-12-01

    In the organic-aqueous phase transfer process of gold nanoparticles, there are two types of distinctive interfaces involving hydrophilic and hydrophobic ligands, the understanding of which is important for the design of functional nanomaterials for analytical/bioanalytical applications and the control over the nanoparticles' nanoactivity and nanotoxicity in different phases. This report describes new findings of an investigation of the quantitative aspect of ligand ion pairing at the capping monolayer structure that drives the phase extraction of gold nanoparticles. Alkanethiolate-capped gold nanoparticles of 8 nm diameter with high size monodispersity (RSD ∼ 5%) were first derivatized by a ligand place exchange reaction with 11-mercaptoundecanoic acid to form a mixed monolayer shell consisting of both hydrophobic (-CH3) and hydrophilic (-COOH) groups. It was followed by quantitative titration of the resulting nanoparticles with a cationic species (-NR4(+)) in a toluene phase, yielding ion pairing of -NR4(+) and -COO(-) on part of the capping monolayer. Analysis of the phase extraction allowed a quantitative determination of the percentage of ion pairing and structural changes in the capping monolayer on the nanoparticles. The results, along with morphological characterization, are discussed in terms of the interfacial structural changes and their implications on the rational design of surface-functionalized nanoparticles and fine tuning of the interfacial reactivity.

  11. Photometric stellar catalogue for TV meteor astronomy

    NASA Astrophysics Data System (ADS)

    Leonov, V. A.; Bagrov, A. V.

    2016-01-01

    Photometry for ordinary astrophysics was carefully developed for its own purposes. As stars radiation is very similar to the blackbody radiation, astronomers measure star illumination in wide or narrow calibrated spectral bands. This is enough for star photometry with precise accuracy and for measuring their light flux in these bands in energetic units. Meteors are moving objects and do not allow collection of more photons then they emit. So meteor observers use the whole spectral band that can be covered by sensitivity of their light sensors. This is why measurements of stellar magnitudes of background stars by these sensors are not the same as catalogued star brightness in standard photometric spectral bands. Here we present a special photometric catalogue of 93 bright non-variable stars of the northern hemisphere, that can be used by meteor observers of standard background whose brightness are calculated in energetic units as well as in non-systematic stellar magnitudes in spectral wavelength of the WATEC 902 sensitivity.

  12. Photometric Redshifts in the IRAC Shallow Survey

    SciTech Connect

    Brodwin, M; Brown, M; Ashby, M; Bian, C; Brand, K; Dey, A; Eisenhardt, P; Eisenstein, D; Gonzalez, A; Huang, J; Kochanek, C; McKenzie, E; Pahre, M; Smith, H; Soifer, B; Stanford, S; Stern, D; Elston, R

    2006-06-13

    Accurate photometric redshifts are calculated for nearly 200,000 galaxies to a 4.5 micron flux limit of {approx} 13 {micro}Jy in the 8.5 deg{sup 2} Spitzer/IRAC Shallow survey. Using a hybrid photometric redshift algorithm incorporating both neural-net and template-fitting techniques, calibrated with over 15,000 spectroscopic redshifts, a redshift accuracy of {sigma} = 0.06 (1+z) is achieved for 95% of galaxies at 0 < z < 1.5. The accuracy is {sigma} = 0.12 (1 + z) for 95% of AGN at 0 < z < 3. Redshift probability functions, central to several ongoing studies of the galaxy population, are computed for the full sample. We demonstrate that these functions accurately represent the true redshift probability density, allowing the calculation of valid confidence intervals for all objects. These probability functions have already been used to successfully identify a population of Spitzer-selected high redshift (z > 1) galaxy clusters. We present one such spectroscopically confirmed cluster at = 1.24, ISCS J1434.2+3426. Finally, we present a measurement of the 4.5 {micro}m-selected galaxy redshift distribution.

  13. Ceres photometric properties from VIR on Dawn

    NASA Astrophysics Data System (ADS)

    Ciarniello, M.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Carrozzo, F. G.; Fonte, S.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; Palomba, E.; Raponi, A.; Tosi, F.; Zambon, F.; Raymond, C. A.; Russell, C. T.; Li, J.-Y.

    2015-10-01

    Dawn spacecraft [1] entered orbit around Ceres on 6 March 2015. During the approach phase to this dwarf planet and later, through the Survey, High Altitude Mapping (HAMO) and Low Altitude Mapping Orbits (LAMO), the Visible and Infrared Mapping Spectrometer (VIR) will perform detailed observations of the surface of the body. VIR [2] is an imaging spectrometer onboard the Dawn mission and it is composed of two spectral channels: the visible (VIS) covering the 0.25 μm - 1.0 μm wavelength range and the infrared (IR) for the 0.95 μm - 5.0 μm interval. During the various phases of the mission, the surface of Ceres will be observed under different observation geometries. The measured signal is then affected by photometric issues that need to be minimized in order to exploit the intrinsic spectral variability of the surface, thus allowing the direct comparison between acquisitions taken under different observation conditions. In order to accomplish this task we perform a photometric reduction of the dataset by means of a simplified Hapke model, following the approach of [3].

  14. An improved apparatus for intragastric titration in the conscious dog.

    PubMed

    Daly, M J; Hartley, R W; Stables, R

    1980-01-01

    An apparatus for automatic intragastric titration with on-line display of results has been described. The apparatus has been validated by titration of exogenous acid injected into the test meal in a reservoir and in vivo by assessing the secretory response of a dog with a gastric fistula to a test meal. A titration display unit provides a record of the secretory response both as a digital printout and a bar chart display. Cimetidine (2 mg kg-1h-1) significantly reduced the secretory response to a test meal.

  15. Novel titration method for surface-functionalised silica

    NASA Astrophysics Data System (ADS)

    Hofen, Kai; Weber, Siegfried; Chan, Chiu Ping Candace; Majewski, Peter

    2011-01-01

    This paper describes three inexpensive and fast analytical methods to characterise grafted particle surfaces. The reaction of silica with (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane and N-(phosphonomethyl)iminodiacetic acid hydrate, respectively, leads to NH2-, SO3H- or COOH-functionalised silica, which were characterised by X-ray photoelectron spectrometry and titration in nonaqueous media as well as with two titration methods in a water-based environment. In the work presented, factors influencing the titrations are pointed out and solutions are presented to overcome these limiting factors are shown.

  16. Ionization behavior of polyphosphoinositides determined via the preparation of pH titration curves using solid-state 31P NMR.

    PubMed

    Graber, Zachary T; Kooijman, Edgar E

    2013-01-01

    Detailed knowledge of the degree of ionization of lipid titratable groups is important for the evaluation of protein-lipid and lipid-lipid interactions. The degree of ionization is commonly evaluated by acid-base titration, but for lipids localized in a multicomponent membrane interface this is not a suitable technique. For phosphomonoester-containing lipids such as the polyphosphoinositides, phosphatidic acid, and ceramide-1-phosphate, this is more conveniently accomplished by (31)P NMR. Here, we describe a solid-state (31)P NMR procedure to construct pH titration curves to determine the degree of ionization of phosphomonoester groups in polyphosphoinositides. This procedure can also be used, with suitable sample preparation conditions, for other important signaling lipids. Access to a solid-state, i.e., magic angle spinning, capable NMR spectrometer is assumed. The procedures described here are valid for a Bruker instrument, but can be adapted for other spectrometers as needed.

  17. Titration of phosphonic acid derivatives in mixtures.

    PubMed

    Wittmann, Z

    1980-01-01

    An analytical procedure is described for the determination of the weak acids phosphonomethyliminodiacetic acid and phosphonomethyliminoacetic acid in their mixtures, and the dissociation constants of phosphonomethyliminoacetic acid are reported.

  18. Asteroid models from the Lowell photometric database

    NASA Astrophysics Data System (ADS)

    Ďurech, J.; Hanuš, J.; Oszkiewicz, D.; Vančo, R.

    2016-03-01

    Context. Information about shapes and spin states of individual asteroids is important for the study of the whole asteroid population. For asteroids from the main belt, most of the shape models available now have been reconstructed from disk-integrated photometry by the lightcurve inversion method. Aims: We want to significantly enlarge the current sample (~350) of available asteroid models. Methods: We use the lightcurve inversion method to derive new shape models and spin states of asteroids from the sparse-in-time photometry compiled in the Lowell Photometric Database. To speed up the time-consuming process of scanning the period parameter space through the use of convex shape models, we use the distributed computing project Asteroids@home, running on the Berkeley Open Infrastructure for Network Computing (BOINC) platform. This way, the period-search interval is divided into hundreds of smaller intervals. These intervals are scanned separately by different volunteers and then joined together. We also use an alternative, faster, approach when searching the best-fit period by using a model of triaxial ellipsoid. By this, we can independently confirm periods found with convex models and also find rotation periods for some of those asteroids for which the convex-model approach gives too many solutions. Results: From the analysis of Lowell photometric data of the first 100 000 numbered asteroids, we derived 328 new models. This almost doubles the number of available models. We tested the reliability of our results by comparing models that were derived from purely Lowell data with those based on dense lightcurves, and we found that the rate of false-positive solutions is very low. We also present updated plots of the distribution of spin obliquities and pole ecliptic longitudes that confirm previous findings about a non-uniform distribution of spin axes. However, the models reconstructed from noisy sparse data are heavily biased towards more elongated bodies with high

  19. Analysis of Photometric Uncertainties in the OGLE-IV Galactic Bulge Microlensing Survey Data

    NASA Astrophysics Data System (ADS)

    Skowron, J.; Udalski, A.; Kozłowski, S.; Szymański, M. K.; Mróz, P.; Wyrzykowski, Ł.; Poleski, R.; Pietrukowicz, P.; Ulaczyk, K.; Pawlak, M.; Soszyński, I.

    2016-01-01

    We present a statistical assessment of both, observed and reported, photometric uncertainties in the OGLE-IV Galactic bulge microlensing survey data. This dataset is widely used for the detection of variable stars, transient objects, discovery of microlensing events, and characterization of the exo-planetary systems. Large collections of RR Lyr stars and Cepheids discovered by the OGLE project toward the Galactic bulge provide light curves based on this dataset. We describe the method of analysis, and provide the procedure, which can be used to update preliminary photometric uncertainties, provided with the light curves, to the ones reflecting the actual observed scatter at a given magnitude and for a given CCD detector of the OGLE-IV camera. This is of key importance for data modeling, in particular, for the correct estimation of the goodness of fit.

  20. The Optical Gravitational Lensing Experiment. OGLE-III Photometric Maps of the Galactic Bulge Fields

    NASA Astrophysics Data System (ADS)

    Szymański, M. K.; Udalski, A.; Soszyński, I.; Kubiak, M.; Pietrzyński, G.; Poleski, R.; Wyrzykowski, Ł.; Ulaczyk, K.

    2011-06-01

    We present OGLE-III Photometric Maps of the Galactic bulge fields observed during the third phase of the OGLE project. This paper describes the last, concluding set of maps based on OGLE-III data. The maps contain precise, calibrated VI photometry of about 340 million stars from 267 fields in the Galactic bulge observed during entire OGLE-III phase (2002-2009), covering about 92 square degrees in the sky. Precise astrometry of these objects is also provided. We briefly discuss the photometry procedures and the quality of the data. We also present sample data and color-magnitude diagrams of the observed fields. All photometric data are available to the astronomical community from the OGLE Internet archive.

  1. Concentration-related response potentiometric titrations to study the interaction of small molecules with large biomolecules.

    PubMed

    Hamidi-Asl, Ezat; Daems, Devin; De Wael, Karolien; Van Camp, Guy; Nagels, Luc J

    2014-12-16

    In the present paper, the utility of a special potentiometric titration approach for recognition and calculation of biomolecule/small-molecule interactions is reported. This approach is fast, sensitive, reproducible, and inexpensive in comparison to the other methods for the determination of the association constant values (Ka) and the interaction energies (ΔG). The potentiometric titration measurement is based on the use of a classical polymeric membrane indicator electrode in a solution of the small-molecule ligand. The biomolecule is used as a titrant. The potential is measured versus a reference electrode and transformed into a concentration-related signal over the entire concentration interval, also at low concentrations, where the millivolt (y-axis) versus log canalyte (x-axis) potentiometric calibration curve is not linear. In the procedure, Ka is calculated for the interaction of cocaine with a cocaine binding aptamer and with an anticocaine antibody. To study the selectivity and cross-reactivity, other oligonucleotides and aptamers are tested, as well as other small ligand molecules such as tetrakis(4-chlorophenyl)borate, metergoline, lidocaine, and bromhexine. The calculated Ka compared favorably to the value reported in the literature using surface plasmon resonance. The potentiometric titration approach called "concentration-related response potentiometry" is used to study molecular interaction for seven macromolecular target molecules and four small-molecule ligands.

  2. Simultaneous determination of influenza virus antihemagglutinin and antineuraminidase antibodies by means of the combined photometric ACU method I. conduct of test.

    PubMed

    Drescher, J

    1976-01-01

    A modification of the photometric ACU (antibody concentration unit) method designated as combined ACU test is described by means of which the titers of both antihemagglutinin (AH) and antineuraminidase (AN) antibodies can be simultaneously determined, using intact homologous influenza virus. In addition, the constants describing the reactions of AH and AN antibodies with their antigens can be obtained. These constants were determined for a series of H2M2 and H3M2 influenza virus strains. This paper gives a detailed description of the conduct of test. The sensitivity and accuracy of AH antibody titration by means of the combinated ACU test was found to be the same as achieved by means of the original ACU test. The same conclusion was reached when comparing the titration of AN antibodies by means of the combined ACU test and of a modified ACU test which, in turn, has been found to be more sensitive and accurate than is AN antibody titration by the enzyme inhibition test. However, the sensitivity of AN antibody titration by the combined ACU test was found to decrease progressively as the ratio of AH to AN antibodies exceeded certain limits.

  3. Development of a photometric system for continuous flow analysis

    PubMed Central

    Bansod, Baban K. S.; Singh, Anirudh K.; Chand, G.; Ganju, A. K.

    2003-01-01

    Most chemical analyses carried out in a clinical laboratory are colorimetric. An improved photometric system is described where a tungsten lamp is the light source, a photo-diode is the detector and a microcontroller 8051 is used for processing and displaying absorbances. The performance characteristics of the instrument are reported. The parameters investigated are photometric linearity, precision and instrumental drift. PMID:18924716

  4. A Titration Technique for Demonstrating a Magma Replenishment Model.

    ERIC Educational Resources Information Center

    Hodder, A. P. W.

    1983-01-01

    Conductiometric titrations can be used to simulate subduction-setting volcanism. Suggestions are made as to the use of this technique in teaching volcanic mechanisms and geochemical indications of tectonic settings. (JN)

  5. THE TITRATION OF YELLOW FEVER VIRUS IN STEGOMYIA MOSQUITOES

    PubMed Central

    Davis, Nelson C.; Frobisher, Martin; Lloyd, Wray

    1933-01-01

    Titrations were made of yellow fever virus in stegomyia mosquitoes, using rhesus monkeys as test animals. It was found that: (a) The average mosquito immediately after engorging on highly infectious blood contained between 1 and 2 million lethal doses of virus. The titer of freshly ingested blood was as high as 1 billion lethal doses of virus per cubic centimeter. (b) During the fortnight succeeding a meal on infectious blood there occurred a reduction of titratable virus to not more than 1 per cent of that present in the freshly fed insects. (c) The titer was somewhat higher at later periods. This rise in titer signified possibly not a multiplication, but merely an increase of extracellular virus and of that easily freed by grinding to a titratable form. (d) At no later stage did the quantity of titratable virus equal that demonstrable in freshly fed insects. PMID:19870190

  6. Microscope Titration and Extraction of DNA from Liver.

    ERIC Educational Resources Information Center

    Mayo, Lois T.; And Others

    1993-01-01

    Describes a simple and inexpensive, one-period activity to extract DNA to make the study of DNA less abstract. A microscope titration is used to determine when cells are ready for DNA extraction. (PR)

  7. Automatic Titrators in the Analytical and Physical Chemistry Laboratories

    NASA Astrophysics Data System (ADS)

    Williams, Kathryn R.

    1998-09-01

    In 1995 the University of Florida received an NSF-ILI grant to purchase six automatic titrators, which have now been successfully integrated into the analytical and physical chemistry teaching laboratories. After they have mastered fundamental techniques, students in the introductory analytical laboratory gain experience with automated analyses in three experiments: the iodimetric analysis of ascorbic acid, the determination of polymer molecular weight, and the analysis of chloride by ion selective electrode. The titrators are also used in the instrumental analysis laboratory for Karl Fischer titrations and the coulometric analysis of EDTA. A physical chemistry experiment, the kinetics of methyl acetate hydrolysis, has also been modified for use with the titrators Instructor write-ups for all experiments may be obtained via JCE Online.

  8. Antarctica photometric survey using PDM13

    NASA Astrophysics Data System (ADS)

    Zalian, Cyrus; Chadid, Merieme

    2014-02-01

    PDM13 is a new graphic interface program dedicated to frequency domain analysis based on the Phase Dispersion Minimization technique (PDM, Stellingwerf 2012). In this paper, we will present the different algorithms running in PDM13, including the Auto-Segmentation, the Gauss-Newton and the PDM algorithms. More details on this triptych are available in our recent paper (Zalian et al., submitted). Their aim is to offer a simple and powerful way to extract frequency. Amongst the numerous improvements offered by the program, we will particularly focus on the reduction of aliases and the ability to look directly for multiple-period phenomena and the Blazhko effect. After that, we will show the first results from PDM13 using the Antarctica photometric survey.

  9. Photometrical research geostationary satellite "SBIRS GEO-2"

    NASA Astrophysics Data System (ADS)

    Sukhov, P. P.; Epishev, V. P; Sukhov, K. P; Kudak, V. I.

    The multicolor photometrical observations GSS "Sbirs Geo-2" were carried in B,V,R filters out during the autumn equinox 2014 and spring 2015 y. Periodic appearance of many light curves and dips of mirror reflections suggests that the GSS was not in orbit in a static position, predetermined three-axis orientation and in dynamic motion. On the basis of computer modeling suggests the following dynamics GSS "Sbirs Geo-2" in orbit. Helically scanning the visible Earth's surface infrared satellite sensors come with period P1 = 15.66 sec. and the rocking of the GSS about the direction of the motion vector of the satellite in orbit with P2 = 62.64 sec., most likely with the purpose to survey the greatest possible portion of the earth's surface.

  10. Photometric Variability of Magnetic White Dwarfs

    NASA Astrophysics Data System (ADS)

    Lawrie, K. A.; Burleigh, M. R.; Brinkworth, C. S.; Marsh, T. R.; Hodgkin, S. T.; Baker, D. E. A.; Cossins, P.; Littlejohns, O. M.; Scott, A. E.; Steele, P. R.

    2013-01-01

    We present our survey results searching for photometric variability and rotation periods of 77 magnetic white dwarfs (MWDs). The sample consists of 24 bright (V < 16), isolated MWDs and 53 MWDs (r' < 18.5) discovered spectroscopically by SDSS. Observations were taken with the 2.5 m Isaac Newton Telescope, La Palma. We determine well-defined periods for 12 stars (16% of the sample) and variability but with poorly constrained periods in a further 13 targets (17%). A period of 7.72 days is found for LHS 5064, the second longest measured for an isolated MWD. Where periods of variability have been determined, the magnetic field strength, temperature, mass and age of the white dwarf have been compared to determine whether any physically interesting correlations emerge.

  11. Photometric Supernova Classification with Machine Learning

    NASA Astrophysics Data System (ADS)

    Lochner, Michelle; McEwen, Jason D.; Peiris, Hiranya V.; Lahav, Ofer; Winter, Max K.

    2016-08-01

    Automated photometric supernova classification has become an active area of research in recent years in light of current and upcoming imaging surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given that spectroscopic confirmation of type for all supernovae discovered will be impossible. Here, we develop a multi-faceted classification pipeline, combining existing and new approaches. Our pipeline consists of two stages: extracting descriptive features from the light curves and classification using a machine learning algorithm. Our feature extraction methods vary from model-dependent techniques, namely SALT2 fits, to more independent techniques that fit parametric models to curves, to a completely model-independent wavelet approach. We cover a range of representative machine learning algorithms, including naive Bayes, k-nearest neighbors, support vector machines, artificial neural networks, and boosted decision trees (BDTs). We test the pipeline on simulated multi-band DES light curves from the Supernova Photometric Classification Challenge. Using the commonly used area under the curve (AUC) of the Receiver Operating Characteristic as a metric, we find that the SALT2 fits and the wavelet approach, with the BDTs algorithm, each achieve an AUC of 0.98, where 1 represents perfect classification. We find that a representative training set is essential for good classification, whatever the feature set or algorithm, with implications for spectroscopic follow-up. Importantly, we find that by using either the SALT2 or the wavelet feature sets with a BDT algorithm, accurate classification is possible purely from light curve data, without the need for any redshift information.

  12. Photometric Properties of Enceladus' South Polar Terrain

    NASA Astrophysics Data System (ADS)

    Annex, Andrew; Verbiscer, A. J.; Helfenstein, P.

    2012-10-01

    Cassini images reveal in exquisite detail the complex and varied terrains within the geologically active south pole of Enceladus. The region is dominated by four parallel rifts or sulci, informally known as tiger stripes, from which plumes comprised primarily of water vapor erupt [1,2]. The rich data set of Cassini images acquired at high spatial resolution (< 0.5 km/pixel) and a variety of viewing and illumination geometries enables the quantitative analysis of surface scattering properties through disk-resolved photometry. Here we investigate the photometric properties of individual terrain units [3] through fits of the Hapke photometric model [4] to data acquired in the clear (CL1 CL2), UV3, GRN, and IR3 filters, centered at 0.61, 0.34, 0.57, and 0.93 μm, respectively. Terrain units include the tiger stripe smooth and platy plank formations, tiger stripe medial dorsum structures, relict tiger stripe structures, south pole funiscular (ropy) plains, south pole lateral fold-and-wedge formations, and the south pole reticulated plains. Despite the constant, ubiquitous infall of plume particles onto the surface, differences in scattering properties, texture, and albedo among terrain units can be discerned. Work supported by NASA's Cassini Data Analysis Program. [1] Porco et al. 2006 Science 311, 1393-1401. [2] Hansen et al. 2008 Nature 456, 477-479. [3] Spencer et al. 2009 in Saturn from Cassini-Huygens (M. K. Dougherty et al. Eds.) 683-724. [4] Hapke 2002 Icarus 157, 523-534.

  13. [Compatibility research of Yiqi Fumai injection with clinical combination based on isothermal titration calorimetry].

    PubMed

    Liu, Hong-yu; Ma, Li-na; Zhang, Ping; Feng, Xue; Xiao, Xiao-he; Liu, Shao-gui; Zhang, Ya-ming

    2015-03-01

    To reveal the characterization of interaction between Chinese and western medicinal injections, isothermal titration calorimetry (ITC) was applied to evaluating the interaction of Yiqi Fumai injection (YQFM, as mode drug) with epinephrine hydrochloride injection (YS) and 5% glucose injection (5% GS). The diversification of Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were determined to judge the reaction types of colliquefaction procedures of different injections. Meanwhile, the fingerprints of YQFM before and after combined with the various injections were compared to validate the results. This work demonstrated that during the titration procedure of YQFM and YS, [ΔH] > T [ΔS] , that was to say the reaction was enthalpy-driving. And the reactive profile indicated that a great deal of heat gave out during the procedure. Obviously, chemical reactions happened and the internal component changed. On the other side, the reaction of YQFM combined with 5% GS was entropy-driving, because [ΔH] < T [ΔS]. The reactive profile showed there was only a little heat released. So non-chemical reactions happened and the major ingredients did not change. ITC could be applied to the evaluation on compatibility of other kinds of Chinese and western medicinal injection combination.

  14. Hierarchical Bayesian inference of galaxy redshift distributions from photometric surveys

    NASA Astrophysics Data System (ADS)

    Leistedt, Boris; Mortlock, Daniel J.; Peiris, Hiranya V.

    2016-08-01

    Accurately characterizing the redshift distributions of galaxies is essential for analysing deep photometric surveys and testing cosmological models. We present a technique to simultaneously infer redshift distributions and individual redshifts from photometric galaxy catalogues. Our model constructs a piecewise constant representation (effectively a histogram) of the distribution of galaxy types and redshifts, the parameters of which are efficiently inferred from noisy photometric flux measurements. This approach can be seen as a generalization of template-fitting photometric redshift methods and relies on a library of spectral templates to relate the photometric fluxes of individual galaxies to their redshifts. We illustrate this technique on simulated galaxy survey data, and demonstrate that it delivers correct posterior distributions on the underlying type and redshift distributions, as well as on the individual types and redshifts of galaxies. We show that even with uninformative priors, large photometric errors and parameter degeneracies, the redshift and type distributions can be recovered robustly thanks to the hierarchical nature of the model, which is not possible with common photometric redshift estimation techniques. As a result, redshift uncertainties can be fully propagated in cosmological analyses for the first time, fulfilling an essential requirement for the current and future generations of surveys.

  15. Photometric normalization of LROC WAC images

    NASA Astrophysics Data System (ADS)

    Sato, H.; Denevi, B.; Robinson, M. S.; Hapke, B. W.; McEwen, A. S.; LROC Science Team

    2010-12-01

    The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) acquires near global coverage on a monthly basis. The WAC is a push frame sensor with a 90° field of view (FOV) in BW mode and 60° FOV in 7-color mode (320 nm to 689 nm). WAC images are acquired during each orbit in 10° latitude segments with cross track coverage of ~50 km. Before mosaicking, WAC images are radiometrically calibrated to remove instrumental artifacts and to convert at sensor radiance to I/F. Images are also photometrically normalized to common viewing and illumination angles (30° phase), a challenge due to the wide angle nature of the WAC where large differences in phase angle are observed in a single image line (±30°). During a single month the equatorial incidence angle drifts about 28° and over the course of ~1 year the lighting completes a 360° cycle. The light scattering properties of the lunar surface depend on incidence(i), emission(e), and phase(p) angles as well as soil properties such as single-scattering albedo and roughness that vary with terrain type and state of maturity [1]. We first tested a Lommel-Seeliger Correction (LSC) [cos(i)/(cos(i) + cos(e))] [2] with a phase function defined by an exponential decay plus 4th order polynomial term [3] which did not provide an adequate solution. Next we employed a LSC with an exponential 2nd order decay phase correction that was an improvement, but still exhibited unacceptable frame-to-frame residuals. In both cases we fitted the LSC I/F vs. phase angle to derive the phase corrections. To date, the best results are with a lunar-lambert function [4] with exponential 2nd order decay phase correction (LLEXP2) [(A1exp(B1p)+A2exp(B2p)+A3) * cos(i)/(cos(e) + cos(i)) + B3cos(i)]. We derived the parameters for the LLEXP2 from repeat imaging of a small region and then corrected that region with excellent results. When this correction was applied to the whole Moon the results were less than optimal - no surprise given the

  16. Extracting Hα flux from photometric data in the J-PLUS survey

    NASA Astrophysics Data System (ADS)

    Vilella-Rojo, G.; Viironen, K.; López-Sanjuan, C.; Cenarro, A. J.; Varela, J.; Díaz-García, L. A.; Cristóbal-Hornillos, D.; Ederoclite, A.; Marín-Franch, A.; Moles, M.

    2015-08-01

    Aims: We present the main steps that will be taken to extract Hα emission flux from Javalambre Photometric Local Universe Survey (J-PLUS) photometric data. Methods: For galaxies with z ≲ 0.015, the Hα+[N ii] emission is covered by the J-PLUS narrow-band filter F660. We explore three different methods to extract the Hα + [N ii] flux from J-PLUS photometric data: a combination of a broad-band and a narrow-band filter (r' and F660), two broad-band and a narrow-band filter (r', i' and F660), and an SED-fitting based method using eight photometric points. To test these methodologies, we simulated J-PLUS data from a sample of 7511 SDSS spectra with measured Hα flux. Based on the same sample, we derive two empirical relations to correct the derived Hα+[N ii] flux from dust extinction and [N ii] contamination. Results: We find that the only unbiased method is the SED-fitting based method. The combination of two filters underestimates the measurements of the Hα + [N ii] flux by 22%, while the three filters method are underestimated by 9%. We study the error budget of the SED-fitting based method and find that, in addition to the photometric error, our measurements have a systematic uncertainty of 4.3%. Several sources contribute to this uncertainty: the differences between our measurement procedure and that used to derive the spectroscopic values, the use of simple stellar populations as templates, and the intrinsic errors of the spectra, which were not taken into account. Apart from that, the empirical corrections for dust extinction and [N ii] contamination add an extra uncertainty of 14%. Conclusions: Given the J-PLUS photometric system, the best methodology to extract Hα + [N ii] flux is the SED-fitting based method. Using this method, we are able to recover reliable Hα fluxes for thousands of nearby galaxies in a robust and homogeneous way. Moreover, each stage of the process (emission line flux, dust extinction correction, and [N ii] decontamination) can be

  17. Photometric identification of blue horizontal branch stars

    NASA Astrophysics Data System (ADS)

    Smith, K. W.; Bailer-Jones, C. A. L.; Klement, R. J.; Xue, X. X.

    2010-11-01

    We investigate the performance of some common machine learning techniques in identifying blue horizontal branch (BHB) stars from photometric data. To train the machine learning algorithms, we use previously published spectroscopic identifications of BHB stars from Sloan digital sky survey (SDSS) data. We investigate the performance of three different techniques, namely k nearest neighbour classification, kernel density estimation for discriminant analysis and a support vector machine (SVM). We discuss the performance of the methods in terms of both completeness (what fraction of input BHB stars are successfully returned as BHB stars) and contamination (what fraction of contaminating sources end up in the output BHB sample). We discuss the prospect of trading off these values, achieving lower contamination at the expense of lower completeness, by adjusting probability thresholds for the classification. We also discuss the role of prior probabilities in the classification performance, and we assess via simulations the reliability of the dataset used for training. Overall it seems that no-prior gives the best completeness, but adopting a prior lowers the contamination. We find that the support vector machine generally delivers the lowest contamination for a given level of completeness, and so is our method of choice. Finally, we classify a large sample of SDSS Data Release 7 (DR7) photometry using the SVM trained on the spectroscopic sample. We identify 27 074 probable BHB stars out of a sample of 294 652 stars. We derive photometric parallaxes and demonstrate that our results are reasonable by comparing to known distances for a selection of globular clusters. We attach our classifications, including probabilities, as an electronic table, so that they can be used either directly as a BHB star catalogue, or as priors to a spectroscopic or other classification method. We also provide our final models so that they can be directly applied to new data. Full Tables 7, A.3

  18. A photometric search for transiting planets

    NASA Astrophysics Data System (ADS)

    Baliber, Nairn Reese

    In the decade since the discovery of the first planet orbiting a main-sequence star other than the Sun, more than 160 planets have been detected in orbit around other stars, most of them discovered by measuring the velocity of the reflexive motion of their parent stars caused by the gravitational pull of the planets. These discoveries produced a population of planets much different to the ones in our Solar System and created interest in other methods to detect these planets. One such method is searching for transits, the slight photometric dimming of stars caused by a close-orbiting, Jupiter-sized planet passing between a star and our line of sight once per orbit. We report results from TeMPEST, the Texas, McDonald Photometric Extrasolar Search for Transits, a transit survey conducted with the McDonald Observatory 0.76 m Prime Focus Corrector (PFC). We monitored five fields of stars in the plane of the Milky Way over the course of two and a half years. We created a photometry pipeline to perform high-precision differential photometry on all of the images, and used a software detection algorithm to detect transit signals in the light curves. Although no transits were found, we calculated our detection probability by determining the fraction of the stars monitored by TeMPEST which were suitable to show transits, measuring the probability of detecting transit signals based on the temporal coverage of our fields, and measuring our detection efficiency by inserting false transits into TeMPEST data to see what fraction could be recovered by our automatic detection software. We conclude that in our entire data set, we generated an effective sample of 2660 stars, a sample in which if any star is showing a transit, it would have been detected. We found no convincing transits in our data, but current statistics from radial velocity surveys indicate that only one in about 1300 of these stars should be showing transits. These numbers are consistent with the lack of transits

  19. One Moon, many measurements 2: Photometric corrections

    NASA Astrophysics Data System (ADS)

    Besse, S.; Yokota, Y.; Boardman, J.; Green, R.; Haruyama, J.; Isaacson, P.; Mall, U.; Matsunaga, T.; Ohtake, M.; Pieters, C.; Staid, M.; Sunshine, J.; Yamamoto, S.

    2013-09-01

    Observations of the lunar surface within the past 10 years have been made with various lunar remote sensing instruments, the Moon Mineralogy Mapper (M3) onboard the Chandrayaan-1 mission, the Spectral Profiler (SP), the Multiband Imager (MI), the Terrain Camera (TC) onboard the SELENE mission, and the ground based USGS Robotic Lunar Observatory (ROLO) for some of them. The lunar phase functions derived from these datasets, which are used in the photometric modeling to correct for the various illumination conditions of the data, are compared to assess their differences and similarity in order to improve interpretations of lunar surface spectra. The phase functions are found to be similar across various phase angles except in the 0-20° range. Differences across the 0-20° range likely result from two different inputs in the photometric modeling of the M3 and SP data: (1) M3 has larger emission angles due to the characteristics of the instrument and the attitude of the spacecraft, and (2) M3 viewing geometry was derived from the local topography whereas SP used a spherical Moon (no topography). The combination of these two different inputs affects the phase function at small phase angles where shadows play a more substantial role, with spatial resolution differences between M3 and SP being another possible source for the differences. SP data are found to be redder (i.e., steeper slope with increasing wavelengths) than MI, M3 and ROLO. Finally, the M3 overall reflectance is also found to be lower than that the other instruments (i.e., MI, SP, and ROLO), generally at least 10% darker than MI. These differences can be observed at local scales in specific examples at hundreds of meters resolutions. At regional and global scales, the same differences are found, which demonstrates the overall stability of the various datasets. The observations from M3, TC, SP and MI are very stable and agree well; however caution should be used when making interpretations based on the

  20. Voyager photometry of Triton - Haze and surface photometric properties

    NASA Technical Reports Server (NTRS)

    Hillier, J.; Helfenstein, P.; Verbiscer, A.; Veverka, J.

    1991-01-01

    The Voyager whole-disk observations of Triton at 0.41, 0.48, and 0.56 micron filter wavelengths are analyzed using a model which combines an improved version of Hapke's photometric equation with a thin atmospheric haze layer in the appropriate spherical geometry. The model is shown to describe accurately the phase curves over a range of phase angles and to agree with disk-resolved brightness scans along the photometric equator and mirror meridian. According to the model, the photometric parameters of Triton's regolith are reasonably typical of icy satellites, except for the extremely high (close to unity) single-scattering albedo.

  1. Potentiometric titration and equivalent weight of humic acid

    USGS Publications Warehouse

    Pommer, A.M.; Breger, I.A.

    1960-01-01

    The "acid nature" of humic acid has been controversial for many years. Some investigators claim that humic acid is a true weak acid, while others feel that its behaviour during potentiometric titration can be accounted for by colloidal adsorption of hydrogen ions. The acid character of humic acid has been reinvestigated using newly-derived relationships for the titration of weak acids with strong base. Re-interpreting the potentiometric titration data published by Thiele and Kettner in 1953, it was found that Merck humic acid behaves as a weak polyelectrolytic acid having an equivalent weight of 150, a pKa of 6.8 to 7.0, and a titration exponent of about 4.8. Interdretation of similar data pertaining to the titration of phenol-formaldehyde and pyrogallol-formaldehyde resins, considered to be analogs for humic acid by Thiele and Kettner, leads to the conclusion that it is not possible to differentiate between adsorption and acid-base reaction for these substances. ?? 1960.

  2. Photometric functions for photoclinometry and other applications

    USGS Publications Warehouse

    McEwen, A.S.

    1991-01-01

    Least-squared fits to the brightness profiles across a disk or "limb darkening" described by Hapke's photometric function are found for the simpler Minnaert and lunar-Lambert functions. The simpler functions are needed to reduce the number of unknown parameters in photoclinometry, especially to distinguish the brightness variations of the surface materials from that due to the resolved topography. The limb darkening varies with the Hapke parameters for macroscopic roughness (??), the single-scattering albedo (w), and the asymmetry factor of the particle phase function (g). Both of the simpler functions generally provide good matches to the limb darkening described by Hapke's function, but the lunar-Lambert function is superior when viewing angles are high and when (??) is less than 30??. Although a nonunique solution for the Minnaert function at high phase angles has been described for smooth surfaces, the discrepancy decreases with increasing (??) and virtually disappears when (??) reaches 30?? to 40??. The variation in limb darkening with w and g, pronounced for smooth surfaces, is reduced or eliminated when the Hapke parameters are in the range typical of most planetary surfaces; this result simplifies the problem of photoclinometry across terrains with variable surface materials. The Minnaert or lunar-Lambert fits to published Hapke models will give photoclinometric solutions that are very similar (>1?? slope discrepancy) to the Hapke-function solutions for nearly all of the bodies and terrains thus far modeled by Hapke's function. ?? 1991.

  3. Photometric Monitoring of Quasars with Kepler

    NASA Astrophysics Data System (ADS)

    Unwin, Stephen C.; Wehrle, A. E.; Wiita, P. J.; Revalski, M.; Silano, D.; Sprague, D.; Di Lorenzo, P.

    2013-01-01

    We have observed the photometric variability of four flat-spectrum radio quasars, and one radio galaxy (Cyg A) with Kepler, since mid-2010. Kepler’s ability to observe uninterrupted for very extended durations provides a unique opportunity to obtain very long time sequences on active galactic nuclei, something that is hard to do even with dedicated ground-based telescope networks. It allows us to examine these light curves for variability on timescales from hours to weeks, and to probe the physical processes involved in accretion around the central black hole and the organization of some of that energy into jets that ultimately power double-lobed radio sources. Kepler was designed to detect exoplanet transits of stars, and the data analysis pipeline is highly optimized for that purpose. We cannot use the standard analysis tools for the quasi-random variability in quasars, so we re-analysed the raw data, and overcame some of the challenges in calibrating these light curves. We briefly discuss some of the issues in producing calibrated light curves for long timescales. For each quasar we computed power spectra, and found power-law slopes of around -2 for most. Although sensitive to quasi-periodic variations, we did not find any convincing evidence for periodicity in any of our targets. This research was carried out, in part, at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2012. California Institute of Technology. Government sponsorship acknowledged.

  4. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B.; Lubin, L.

    2004-07-01

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the rms scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.04 magnitudes, with some dependence on filter. The largest errors seen are 0.07 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  5. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B.; Lubin, L.

    2002-12-01

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the mean scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.04 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  6. The Accuracy of WFPC2 Photometric Zeropoints

    NASA Astrophysics Data System (ADS)

    Heyer, I.; Richardson, M.; Whitmore, B. C.; Lubin, L. M.

    The accuracy of WFPC2 photometric zeropoints is examined using two methods. The first approach compares the zeropoints from five sources: Holtzman (1995), the HST Data Handbook (1995 and 2002 versions), and Dolphin (both 2000 and 2002 versions). We find the mean scatter between the different studies to be: 0.043 mag for F336W, 0.034 mag for F439W, 0.016 mag for F555W, and 0.018 mag for F814W. The second approach is a comparison of WFPC2 observations of NGC2419 with ground-based photometry from Stetson (from his website) and Saha et al. (private communication). The tentative agreement between these comparisons is similar to the historical zeropoint comparisons. Hence we conclude that the true uncertainty of WFPC2 zeropoints is currently about 0.02-0.03 magnitudes. Since Poisson statistics would predict that 1% absolute accuracy should be attainable, we conclude that there are still systematic error sources which have not yet been identified.

  7. BROADBAND PHOTOMETRIC REVERBERATION MAPPING OF NGC 4395

    SciTech Connect

    Edri, Haim; Rafter, Stephen E.; Kaspi, Shai; Behar, Ehud; Chelouche, Doron E-mail: shai@physics.technion.ac.il E-mail: doron@sci.haifa.ac.il

    2012-09-01

    We present results of broadband photometric reverberation mapping (RM) to measure the radius of the broad-line region, and subsequently the black hole mass (M{sub BH}), in the nearby, low-luminosity active galactic nuclei NGC 4395. Using the Wise Observatory's 1 m telescope equipped with the Sloan Digital Sky Survey g', r', and i' broadband filters, we monitored NGC 4395 for nine consecutive nights and obtained three light curves each with over 250 data points. The g' and r' bands include time variable contributions from H{beta} and H{alpha}, respectively, plus continuum. The i' band is free of broad lines and covers exclusively continuum. We show that by looking for a peak in the difference between the cross-correlation and the auto-correlation functions for all combinations of filters, we can get a reliable estimate of the time lag necessary to compute M{sub BH}. We measure the time lag for H{alpha} to be 3.6 {+-} 0.8 hr, comparable to previous studies using the line-resolved spectroscopic RM method. We argue that this lag implies a black hole mass of M{sub BH} = (4.9 {+-} 2.6) Multiplication-Sign 10{sup 4} M{sub Sun }.

  8. Photometric stability of the lunar surface

    USGS Publications Warehouse

    Kieffer, H.H.

    1997-01-01

    The rate at which cratering events currently occur on the Moon is considered in light of their influence on the use of the Moon as a radiometric standard. The radiometric effect of small impact events is determined empirically from the study of Clementine images. Events that would change the integral brightness of the moon by 1% are expected once per 1.4 Gyr. Events that cause a 1% shift in one pixel for low Earth-orbiting instruments with a 1-km nadir field of view are expected approximately once each 43 Myr. Events discernible at 1% radiometric resolution with a 5 arc-sec telescope resolution correspond to crater diameters of approximately 210 m and are expected once every 200 years. These rates are uncertain by a factor of two. For a fixed illumination and observation geometry, the Moon can be considered photometrically stable to 1 ?? 10-8per annum for irradiance, and 1 ?? 10-7per annum for radiance at a resolution common for spacecraft imaging instruments, exceeding reasonable instrument goals by six orders of magnitude. ?? 1997 Academic Press.

  9. A comparison of coulometric titration and potentiometric determination of chloride concentration in rumen fluid.

    PubMed

    Cebra, Christopher K.; Tornquist, Susan J.; Vap, Lomda M.; Dodson, Linda A.

    2001-01-01

    The concentration of chloride ions in rumen fluid is a useful measure of obstructive gastrointestinal disease in ruminants and camelids. However, rumen fluid is very different from other biological fluids in its bacterial populations, consistency, and concentrations of various anions. Two methods of determining the chloride concentration in biological fluids were compared using centrifuged and filtered rumen fluid containing different amounts of sodium chloride. Although coulometric titration and potentiometric electrode analysis yielded results that had a strong linear relationship, the results of potentiometry were consistently and significantly higher, by about 20 mEq/L. This difference was investigated further by analyzing a series of fluids containing different concentrations of sodium acetate. Acetate was detected as chloride (0.21 chloride molecules per acetate molecule) by potentiometry but not by coulometric titration. Therefore, the acetate concentration of rumen fluid was the most likely cause of the discrepancy between tests in the original trial. In conclusion, the coulometric procedure may be more accurate than the potentiometric procedure for measuring rumen chloride when the concentrations of possible confounding ions are unknown.

  10. Differential titration of bases in glacial acetic acid.

    PubMed

    Castellano, T; Medwick, T; Shinkai, J H; Bailey, L

    1981-01-01

    A study of bases in acetic acid and their differential titration was carried out. The overall basicity constants for 20 bases were measured in acetic acid, and the differential titration of five binary mixtures of variable delta pKb values in acetic acid was followed using a glass electrode-modified calomel electrode system. Agreement with literature values was good. A leveling diagram was constructed that indicated that bases stronger than aqueous pKb 10 are leveled to an acetous pKb 5.69, whereas weaker bases are not leveled but instead exhibit their own intrinsic basicity, with the acetous pKb to aqueous pKb values being linearly related (slope 1.18, correlation coefficient 0.962). A minimum acetous delta pKb of four units is required for the satisfactory differential titration of two bases in acetic acid.

  11. Probabilistic Photometric Redshifts in the Era of Petascale Astronomy

    SciTech Connect

    Carrasco Kind, Matias

    2014-01-01

    With the growth of large photometric surveys, accurately estimating photometric redshifts, preferably as a probability density function (PDF), and fully understanding the implicit systematic uncertainties in this process has become increasingly important. These surveys are expected to obtain images of billions of distinct galaxies. As a result, storing and analyzing all of these photometric redshift PDFs will be non-trivial, and this challenge becomes even more severe if a survey plans to compute and store multiple different PDFs. In this thesis, we have developed an end-to-end framework that will compute accurate and robust photometric redshift PDFs for massive data sets by using two new, state-of-the-art machine learning techniques that are based on a random forest and a random atlas, respectively. By using data from several photometric surveys, we demonstrate the applicability of these new techniques, and we demonstrate that our new approach is among the best techniques currently available. We also show how different techniques can be combined by using novel Bayesian techniques to improve the photometric redshift precision to unprecedented levels while also presenting new approaches to better identify outliers. In addition, our framework provides supplementary information regarding the data being analyzed, including unbiased estimates of the accuracy of the technique without resorting to a validation data set, identification of poor photometric redshift areas within the parameter space occupied by the spectroscopic training data, and a quantification of the relative importance of the variables used during the estimation process. Furthermore, we present a new approach to represent and store photometric redshift PDFs by using a sparse representation with outstanding compression and reconstruction capabilities. We also demonstrate how this framework can also be directly incorporated into cosmological analyses. The new techniques presented in this thesis are crucial

  12. Error assessment in recombinant baculovirus titration: evaluation of different methods.

    PubMed

    Roldão, António; Oliveira, Rui; Carrondo, Manuel J T; Alves, Paula M

    2009-07-01

    The success of baculovirus/insect cells system in heterologous protein expression depends on the robustness and efficiency of the production workflow. It is essential that process parameters are controlled and include as little variability as possible. The multiplicity of infection (MOI) is the most critical factor since irreproducible MOIs caused by inaccurate estimation of viral titers hinder batch consistency and process optimization. This lack of accuracy is related to intrinsic characteristics of the method such as the inability to distinguish between infectious and non-infectious baculovirus. In this study, several methods for baculovirus titration were compared. The most critical issues identified were the incubation time and cell concentration at the time of infection. These variables influence strongly the accuracy of titers and must be defined for optimal performance of the titration method. Although the standard errors of the methods varied significantly (7-36%), titers were within the same order of magnitude; thus, viral titers can be considered independent of the method of titration. A cost analysis of the baculovirus titration methods used in this study showed that the alamarblue, real time Q-PCR and plaque assays were the most expensive techniques. The remaining methods cost on average 75% less than the former methods. Based on the cost, time and error analysis undertaken in this study, the end-point dilution assay, microculture tetrazolium assay and flow cytometric assay were found to be the techniques that combine all these three main factors better. Nevertheless, it is always recommended to confirm the accuracy of the titration either by comparison with a well characterized baculovirus reference stock or by titration using two different methods and verification of the variability of results.

  13. Anion-exchange nanospheres as titration reagents for anionic analytes.

    PubMed

    Zhai, Jingying; Xie, Xiaojiang; Bakker, Eric

    2015-08-18

    We present here anion-exchange nanospheres as novel titration reagents for anions. The nanospheres contain a lipophilic cation for which the counterion is initially Cl(-). Ion exchange takes place between Cl(-) in the nanospheres and a more lipophilic anion in the sample, such as ClO4(-) and NO3(-). Consecutive titration in the same sample solution for ClO4(-) and NO3(-) were demonstrated. As an application, the concentration of NO3(-) in spinach was successfully determined using this method.

  14. Accuracy of the endpoint assay for virus titration.

    PubMed

    Nielsen, L K; Smyth, G K; Greenfield, P F

    1992-01-01

    The statistics of estimators used with the endpoint assay for virus titration were investigated. For a standard assay with 10 wells/dilution, the graphical estimator traditionally used was found to produce estimates with significant positive bias and a relatively low accuracy. Furthermore, the graphical estimator was found to be inconsistent. A superior estimator based on the maximum likelihood principle was developed. The results are discussed in relation to the choice between the endpoint titration assay and the plaque assay, and an alternative two-stage assay is presented.

  15. Analyzing a kinetic titration series using affinity biosensors.

    PubMed

    Karlsson, Robert; Katsamba, Phinikoula S; Nordin, Helena; Pol, Ewa; Myszka, David G

    2006-02-01

    The classical method of measuring binding constants with affinity-based biosensors involves testing several analyte concentrations over the same ligand surface and regenerating the surface between binding cycles. Here we describe an alternative approach to collecting kinetic binding data, which we call "kinetic titration." This method involves sequentially injecting an analyte concentration series without any regeneration steps. Through a combination of simulation and experimentation, we show that this method can be as robust as the classical method of analysis. In addition, kinetic titrations can be more efficient than the conventional data collection method and allow us to fully characterize analyte binding to ligand surfaces that are difficult to regenerate.

  16. A fully automatic system for acid-base coulometric titrations.

    PubMed

    Cladera, A; Caro, A; Estela, J M; Cerdà, V

    1990-01-01

    An automatic system for acid-base titrations by electrogeneration of H(+) and OH(-) ions, with potentiometric end-point detection, was developed. The system includes a PC-compatible computer for instrumental control, data acquisition and processing, which allows up to 13 samples to be analysed sequentially with no human intervention.The system performance was tested on the titration of standard solutions, which it carried out with low errors and RSD. It was subsequently applied to the analysis of various samples of environmental and nutritional interest, specifically waters, soft drinks and wines.

  17. The Unusual Photometric Variability of the PMS Star GM Cep

    NASA Astrophysics Data System (ADS)

    Semkov, E. H.; Ibryamov, S. I.; Peneva, S. P.; Milanov, T. R.; Stoyanov, K. A.; Stateva, I. K.; Kjurkchieva, D. P.; Dimitrov, D. P.; Radeva, V. S.

    2015-03-01

    Results from UBVRI photometric observations of the pre-main sequence star GM Cep obtained in the period 2011 April-2014 August are reported in the paper. Presented data are a continuation of our photometric monitoring of the star started in 2008. GM Cep is located in the field of the young open cluster Trumpler 37 and over the past years it has been an object of intense photometric and spectral studies. The star shows a strong photometric variability interpreted as a possible outburst from EXor type in previous studies. Our photometric data for a period of over six years show a large amplitude variability (ΔV ~ 2.3 mag) and several deep minimums in brightness are observed. The analysis of the collected multicolour photometric data show the typical of UX Ori variables a colour reversal during the minimums in brightness. The observed decreases in brightness have a different shape, and evidences of periodicity are not detected. At the same time, high amplitude rapid variations in brightness typical for the classical T Tauri stars also present on the light curve of GM Cep. The spectrum of GM Cep shows the typical of classical T Tauri stars wide Hα emission line and absorption lines of some metals. We calculate the outer radius of the Hα emitting region as 10.4 ± 0.5 R⊙ and the accretion rate as 1.8 × 10- 7 M⊙ yr- 1.

  18. Photometric Survey for Asynchronous Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Pravec, P.

    2005-05-01

    Asynchronous binary asteroids have been found to be abundant among fast- spinning near-Earth asteroids (NEAs) smaller than 2 km in diameter; Pravec et al. (2005, Icarus, submitted) derived that 15 +/- 4 % of NEAs in the size range 0.3 to 2 km are binary with the secondary-to-primary mean diameter ratio >=0.18. The early re-sults from the surveys of the Vesta family and the Hungaria group (Ryan et al., 2004, Planet. Space Sci. 42, 1093; 2004, Bull. Amer. Astron. Society 36, 1181; Warner et al., 2005, IAU Circ. 8511) suggest that the popula-tion extends beyond the region of terrestrial planets, but with characteristics shifted to larger sizes and longer periods; the four known binaries in the Vesta family/Hungaria group are 3 to 6 km large and they have primary rotation periods in a range of 3 to ~4 h, i.e., on the tail of the distribution of primary rotation periods of NEAs. The comparison suggests that formation and evolution mechanisms of asynchronous NEA and main-belt binaries may be similar and are related to their fast spins and rubble-pile structure. None of the current theories of their formation of evolution, however, explains the observed properties of both NEA and main- belt asynchronous bina-ries in full. We have established a collaborative observational program, called "Photometric Survey for Asynchro-nous Binary Asteroids" to discover and describe asynchronous binaries over a range of heliocentric distances from NEAs through Mars-crossers to inner main-belt asteroids. One new binary Amor asteroid, 2005 AB has been found during the first few months of the survey operation (Reddy et al., 2005, IAU Circ. 8483), and we have obtained follow-up data for two other binary systems. I outline the motivations, the technique, and the strategy of the Survey.

  19. Titrations using an apparatus for recording the antilogarithm of pH or pM.

    PubMed

    Johansson, A

    1974-12-01

    A titration apparatus plotting either the concentration of sample ion or the concentration of titrant ion has been tested. An antilog apparatus, converting measured e.m.f. values into concentrations is connected to ordinary titration equipment. The instrument has been tested by means of acid-base titrations (titrations of mixtures of weak acids and of a weak and a strong acid), precipitation titrations (determination of the chloride concentration in tap-water, titration of mixtures of halides), titrations with ion-selective electrodes (determination of the fluoride content of toothpaste) and complexometric titrations (determination of copper with EDTA, using mercuric ion as indicator ion and amalgamated silver rod as indicator electrode, or using a copper-selective indicator electrode). The method considerably simplifies the evaluation of the results as compared to conventional potentiometric titrations.

  20. FIA titrations of phenothiazine derivatives in aqueous micellar and non-aqueous media.

    PubMed

    Nemcová, Irena; Nesmerák, Karel; Rychlovský, Petr; Koutníková, Jitka

    2005-02-15

    New methods of flow injection analysis (FIA) neutralization titrations of phenothiazine derivatives in aqueous micellar medium of a cationic surfactant using potentiometric and spectrophotometric detection were proposed; titrations with a mixing gradient chamber and high-speed titrations were compared. The FIA titration method in non-aqueous media based on an official method of determination (titration with perchloric acid in anhydrous acetic acid) was also developed. Under optimized reaction conditions and flow-through parameters, the calibration range and equations, the sensitivity, and the repeatability of all methods were found and discussed. All titrations were assayed for medicinal forms.

  1. Characterisation of iron binding ligands in seawater by reverse titration.

    PubMed

    Hawkes, Jeffrey A; Gledhill, Martha; Connelly, Douglas P; Achterberg, Eric P

    2013-03-01

    Here we demonstrate the use of reverse titration - competitive ligand exchange-adsorptive cathodic stripping voltammetry (RT-CLE-ACSV) for the analysis of iron (Fe) binding ligands in seawater. In contrast to the forward titration, which examines excess ligands in solution, RT-CLE-ACSV examines the existing Fe-ligand complexes by increasing the concentration of added (electroactive) ligand (1-nitroso-2-naphthol) and analysis of the proportion of Fe bound to the added ligand. The data manipulation allows the accurate characterisation of ligands at equal or lower concentrations than Fe in seawater, and disregards electrochemically inert dissolved Fe such as some colloidal phases. The method is thus superior to the forward titration in environments with high Fe and low ligand concentrations or high concentrations of inert Fe. We validated the technique using the siderophore ligand ferrioxamine B, and observed a stability constant [Formula: see text] of 0.74-4.37×10(21) mol(-1), in agreement with previous results. We also successfully analysed samples from coastal waters and a deep ocean hydrothermal plume. Samples from these environments could not be analysed with confidence using the forward titration, highlighting the effectiveness of the RT-CLE-ACSV technique in waters with high concentrations of inert Fe.

  2. Coulometric titration of ruthenium and iridium by the generated hydroquinone

    SciTech Connect

    Organeysan, L.S.; Butakova, N.A.

    1986-05-10

    This paper studies the electrogeneration of hydroquinone from solutions of quinone on platinum and glass-carbon electrodes in HC1 and H/sub 2/SO/sub 4/ media of different concentrations, to select the optimal conditions for the coulometric titration of Ru(IV) and Ir(IV).

  3. A General Simulator for Acid-Base Titrations

    NASA Astrophysics Data System (ADS)

    de Levie, Robert

    1999-07-01

    General formal expressions are provided to facilitate the automatic computer calculation of acid-base titration curves of arbitrary mixtures of acids, bases, and salts, without and with activity corrections based on the Davies equation. Explicit relations are also given for the buffer strength of mixtures of acids, bases, and salts.

  4. Analysis of the purity of cetrimide by titrations.

    PubMed

    Rasmussen, Claus D; Nielsen, Hans B; Andersen, Jens E T

    2006-01-01

    The purity of cetrimide, trimethyl tetradecyl ammonium bromide (TTAB), which is an important preservative of many cosmetic and pharmaceutical products, was determined by three independent methods of titration. Traditionally, cetrimide was analysed by an assay method of the European Pharmacopoeia, which showed consistently a low purity of cetrimide with associated large standard deviations, however. A systematic 3% bias of the European Pharmacopoeia assay method was identified by comparing the result with results of two alternative methods of titration that exhibited high precision and high accuracy. Titration by perchloric acid showed a 99.69% +/- 0.05% purity of cetrimide, and titration by silver nitrate showed a 99.85% +/- 0.05% purity, while the traditional assay method predicted a purity of only 97.1% +/- 0.4%. It was found that the discrepancy could be identified as differences in selectivity during the extraction step of the European Pharmacopoeia assay method. The distribution coefficients between chloroform and water of cetrimide and the corresponding iodide species (TTAI) were thus determined as 2150 +/- 50 M(-1) and 68000 +/- 4000 M(-1), respectively.

  5. Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

    ERIC Educational Resources Information Center

    Moore, Dale E.; Goode, David R.; Seney, Caryn S.; Boatwright, Jennifer M.

    2016-01-01

    College chemistry faculties might not have considered including isothermal titration calorimetry (ITC) in their majors' curriculum because experimental data from this instrumental method are often analyzed via automation (software). However, the software-based data analysis can be replaced with a spreadsheet-based analysis that is readily…

  6. Coulometric calcium pump for thin layer sample titrations.

    PubMed

    Ghahraman Afshar, Majid; Crespo, Gastón A; Bakker, Eric

    2015-10-01

    A selective electrochemical calcium pump based on a fast diffusive calcium ionophore-based membrane is reported. An initially nonpolarized ionophore-based membrane allows one to establish a net calcium flux by applying a potential step function (i.e., 250 mV for 30 s). The resulting calcium flux is released into a microliter scale thin layer reservoir, and the resulting ion perturbation is monitored by either a potentiometric or a coulometric readout. This chemical perturbation in the thin layer thus acts as a titration agent that is precisely controlled by coulometry. A linear correlation between released and detected calcium is confirmed by the two different readout modes. Having demonstrated the efficiency of the calcium pump in background electrolyte solutions, a complexometric titration with known concentrations of EDTA in the thin layer sample was performed. With the potentiometric readout, titrations in the range of 0.25-0.75 mM gave a precision of 3%, whereas the coulometric readout gave a range of 0.02-0.12 mM and a precision of 2%. Improved precision is expected by better control of the thin layer geometry by microfabrication. The significance of this work is that the coupling of a selective calcium pump with a thin layer element can give rise to rapid and complete sample concentration changes and result in a promising platform for titrations either on the laboratory bench or for in situ measurements in environmental or diagnostic settings.

  7. Chemical force titrations of functionalized Si(111) surfaces.

    PubMed

    Mengistu, Tadesse Z; Goel, Vishya; Horton, J Hugh; Morin, Sylvie

    2006-06-01

    Chemical force titrations-plots of the adhesive force between an atomic force microscope tip and sample as a function of pH-were acquired on alkyl monolayer-derivatized Si(111) surfaces. Gold-coated AFM tips modified with thioalkanoic acid self-assembled monolayers (SAM) were employed. Alkyl monolayer-derivatized Si(111) surfaces terminated with methyl, carboxyl, and amine groups were produced via hydrosilylation reactions between 1-alkene reagents and H-terminated silicon. The functionalized surfaces were characterized using standard surface science techniques (AFM, FTIR, and XPS). Titration of the methyl-terminated surface using the modified (carboxyl-terminated) atomic force microscope tip resulted in a small pH-independent hydrophobic interaction. Titration of the amine-terminated surface using the same tip resulted in the determination of a surface pKa of 5.8 for the amine from the pH value from the maximum in the force titration curve. A pK(1/2) of 4.3 was determined for the carboxyl-terminated Si(111) in a similar way. These results will be discussed in relation to the modified Si(111) surface chemistry and organic layer structure, as well as with respect to existing results on Au surfaces modified with SAMs bearing the same functional groups.

  8. Using Spreadsheets to Produce Acid-Base Titration Curves.

    ERIC Educational Resources Information Center

    Cawley, Martin James; Parkinson, John

    1995-01-01

    Describes two spreadsheets for producing acid-base titration curves, one uses relatively simple cell formulae that can be written into the spreadsheet by inexperienced students and the second uses more complex formulae that are best written by the teacher. (JRH)

  9. Production of first generation adenoviral vectors for preclinical protocols: amplification, purification and functional titration.

    PubMed

    Armendáriz-Borunda, Juan; Bastidas-Ramírez, Blanca Estela; Sandoval-Rodríguez, Ana; González-Cuevas, Jaime; Gómez-Meda, Belinda; García-Bañuelos, Jesús

    2011-11-01

    Gene therapy represents a promising approach in the treatment of several diseases. Currently, the ideal vector has yet to be designed; though, adenoviral vectors (Ad-v) have provided the most utilized tool for gene transfer due principally to their simple production, among other specific characteristics. Ad-v viability represents a critical variable that may be affected by storage or shipping conditions and therefore it is advisable to be assessed previously to protocol performance. The present work is unique in this matter, as the complete detailed process to obtain Ad-v of preclinical grade is explained. Amplification in permissive HEK-293 cells, purification in CsCl gradients in a period of 10 h, spectrophotometric titration of viral particles (VP) and titration of infectious units (IU), yielding batches of AdβGal, AdGFP, AdHuPA and AdMMP8, of approximately 10¹³-10¹⁴ VP and 10¹²-10¹³ IU were carried out. In vivo functionality of therapeutic AdHuPA and AdMMP8 was evidenced in rats presenting CCl₄-induced fibrosis, as more than 60% of fibrosis was eliminated in livers after systemic delivery through iliac vein in comparison with irrelevant AdβGal. Time required to accomplish the whole Ad-v production steps, including IU titration was 20 to 30 days. We conclude that production of Ad-v following standard operating procedures assuring vector functionality and the possibility to effectively evaluate experimental gene therapy results, leaving aside the use of high-cost commercial kits or sophisticated instrumentation, can be performed in a conventional laboratory of cell culture.

  10. Photometric Studies of GEO Orbital Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Ed; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the Cerro Tololo Inter- American Observatory (CTIO) 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R=15th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? More than 90 calibrated sequences of R-B-V-I-R magnitudes for a sample of 50 objects have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus the B-R color is a true measure of the surface of the debris piece facing the

  11. Optical Photometric Observations of GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Edwin S.; Abercromby, Kira J.; Kelecy, Thomas M.; Horstman, Matt

    2010-01-01

    We report on a continuing program of optical photometric measurements of faint orbital debris at geosynchronous Earth orbit (GEO). These observations can be compared with laboratory studies of actual spacecraft materials in an effort to determine what the faint debris at GEO may be. We have optical observations from Cerro Tololo Inter-American Observatory (CTIO) in Chile of two samples of debris: 1. GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Curtis-Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the CTIO/SMARTS 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 t11 magnitude that are discovered in the MODEST survey. 2. A smaller sample of high area to mass ratio (AMR) objects discovered independently, and acquired using predictions from orbits derived from independent tracking data collected days prior to the observations. Our optical observations in standard astronomical BVRI filters are done with either telescope, and with the telescope tracking the debris object at the object's angular rate. Observations in different filters are obtained sequentially. We have obtained 71 calibrated sequences of R-B-V-I-R magnitudes. A total of 66 of these sequences have 3 or more good measurements in all filters (not contaminated by star streaks or in Earth's shadow). Most of these sequences show brightness variations, but a small subset has observed brightness variations consistent with that expected from observational errors alone. The majority of these stable objects are redder than a solar color in both B-R and R-I. There is no dependence on color with brightness. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and

  12. Photometric Studies of Orbital Debris at GEO

    NASA Technical Reports Server (NTRS)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Ed; Abercromby, Kira J.; Foreman, Gary; Hortsman, Matt

    2009-01-01

    Orbital debris represents a significant and increasing risk to operational spacecraft. Here we report on photometric observations made in standard BVRI filters at the Cerro Tololo Inter-American Observatory (CTIO) in an effort to determine the physical characteristics of optically faint debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan s 0.6-m Curtis-Schmidt telescope (known as MODEST, for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the CTIO/SMARTS 0.9-m for orbits and photometry. For a sample of 50 objects, calibrated sequences in RB- V-I-R filters have been obtained with the CTIO/SMARTS 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could imply that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For irregularly shaped objects tumbling at unknown orientations and rates, such sequential filter measurements using one telescope are subject to large errors for interpretation. If all observations in all filters in a particular sequence are of the same surface at the same solar and viewing angles, then the colors are meaningful. Where this is not the case, interpretation of the observed colors is impossible. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO/SMARTS 0.9-m observes in B, and the Schmidt in R. The CCD cameras are electronically linked together so that the start time and duration of observations are both the same to better than 50 milliseconds. Now the observed B-R color is a true measure of the scattered illuminated area of the debris piece for that observation.

  13. A photometric model for asteroid (21) Lutetia

    NASA Astrophysics Data System (ADS)

    Hasselmann, P.; Leyrat, C.; Fornasier, S.; Barucci, M.; Lazzaro, D.

    2014-07-01

    (21) Lutetia has been successfully observed (July 10, 2010) by the ESA Rosetta spacecraft during its journey toward the comet 67P/Churyumov-Gerasimenko (Sierks et al. 2011, Coradini et al. 2011). All the available data show intriguing characteristics with a complex surface composition interpretation (Barucci et al. 2012). The quite high mean density estimation (3.4±0.3, Pätzold et al. 2011) together with the unmatching density derived from the most probable surface compositions raise a hypothesis of (21) Lutetia having a metal core (Weiss et al 2012). The surface geology of (21) Lutetia is also highly complex with significant interactions between ancient and more recent structures (Thomas et al; 2012). The large craters and lineaments show that the object was heavily battered in the past, probably losing almost all of its crust in the process (Massironi et al 2012). If (21) Lutetia is a partially differentiated asteroid with an impact-stripped crust, a complete study of variegations might help in elucidating this event. Regions or strips of different albedo might indicate heavier- or lighter-battered surface histories. Albedo variations have been detected by Leyrat et al. (2012) in the visible wavelengths. In this work, we present a deeper analysis of the Lutetia photometric properties. For such analysis, a full set of pipelines was developed in the Python 2.7.6 language. Images obtained by the OSIRIS cameras, NAC and WAC, were used alongside the shape model provided by L. Jorda to derive for each facet the luminance angles and the correct I/F. The pipeline takes image pixels and matches with facets on different observational conditions. Facets are iteratively fitted by a phase function and a disk function. Several phase functions were tested as Akimov (1976), Kaasalainen (Kaasalainen et al. 2003), Schroder (Schroder et al; 2013) and polynomial and were implemented; for disk function, McEwen (1991), Akimov and Minnaert (1941) were used. The method can be also

  14. Photometric constraints on binary asteroid dynamics

    NASA Astrophysics Data System (ADS)

    Scheirich, Peter

    2015-08-01

    To date, about 50 binary NEAs, 20 Mars-crossing and 80 small MB asteroids are known. We observe also a population of about 200 unbound asteroid systems (asteroid pairs). I will review the photometric observational data we have for the best observed cases and compare them with theories of binary and paired asteroids evolution.The observed characteristics of asteroid systems suggest their formation by rotational fission of parent rubble-pile asteroids after being spun up by the YORP effect. The angular momentum content of binary asteroids is close to critical. The orientations of satellite orbits of observed binary systems are non-random; the orbital poles concentrate near the obliquities of 0 and 180 degrees, i.e., near the YORP asymptotic states.Recently, a significant excess of retrograde satellite orbits was detected, which is not yet explained characteristic.An evolution of binary system depend heavily on the BYORP effect. If BYORP is contractive, the primary and secondary could end in a tidal-BYORP equilibrium. Observations of mutual events between binary components in at least four apparitions are needed for BYORP to be revealed by detecting a quadratic drift in mean anomaly of the satellite. I will show the observational evidence of single-synchronous binary asteroid with tidally locked satellite (175706 1996 FG3), i.e, with the quadratic drift equal to zero, and binary asteroid with contracting orbit (88710 2001 SL9), with positive value of the quadratic drift (the solution for the quadratic drift is ambiguous so far, with possible values of 5 and 8 deg/yr2).The spin configuration of the satellite play a crucial role in the evolution of the system under the influence of the BYORP effect. I will show that the rotational lightcurves of the satellites show that most of them have small libration amplitudes (up to 20 deg.), with a few interesting exceptions.Acknowledgements: This work has been supported by the Grant Agency of the Czech Republic, Grant P209

  15. Photometric calibrations for 21st century science

    SciTech Connect

    Kent, Stephen; Kaiser, Mary Elizabeth; Deustua, Susana E.; Smith, J.Allyn; Adelman, Saul; Allam, Sahar S.; Baptista, Brian; Bohlin, Ralph C.; Clem, James L.; Conley, Alex; Edelstein, Jerry; /UC, Berkeley, Space Sci. Dept. /NOAO, Tucson

    2009-02-01

    The answers to fundamental science questions in astrophysics, ranging from the history of the expansion of the universe to the sizes of nearby stars, hinge on our ability to make precise measurements of diverse astronomical objects. As our knowledge of the underlying physics of objects improves along with advances in detectors and instrumentation, the limits on our capability to extract science from measurements is set, not by our lack of understanding of the nature of these objects, but rather by the most mundane of all issues: the precision with which we can calibrate observations in physical units. In principle, photometric calibration is a solved problem - laboratory reference standards such as blackbody furnaces achieve precisions well in excess of those needed for astrophysics. In practice, however, transferring the calibration from these laboratory standards to astronomical objects of interest is far from trivial - the transfer must reach outside the atmosphere, extend over 4{pi} steradians of sky, cover a wide range of wavelengths, and span an enormous dynamic range in intensity. Virtually all spectrophotometric observations today are calibrated against one or more stellar reference sources, such as Vega, which are themselves tied back to laboratory standards in a variety of ways. This system's accuracy is not uniform. Selected regions of the electromagnetic spectrum are calibrated extremely well, but discontinuities of a few percent still exist, e.g., between the optical and infrared. Independently, model stellar atmospheres are used to calibrate the spectra of selected white dwarf stars, e.g. the HST system, but the ultimate accuracy of this system should be verified against laboratory sources. Our traditional standard star systems, while sufficient until now, need to be improved and extended in order to serve future astrophysics experiments. This white paper calls for a program to improve upon and expand the current networks of spectrophotometrically

  16. Redox titrations of carbon monoxide dehydrogenase from Clostridium thermoaceticum.

    PubMed

    Shin, W; Stafford, P R; Lindahl, P A

    1992-07-01

    Redox titrations of carbon monoxide dehydrogenase (CODH) from Clostridium thermoaceticum were performed using the reductant CO and the oxidant thionin. Titrations were followed at 420 nm, a wavelength sensitive to redox changes of the iron-sulfur clusters in the enzyme. When CODH was oxidized by just enough thionin to maximize A420, two molecules of CO per mole of CODH dimer (4 equiv/mol) reduced the enzyme fully. Likewise, 4 equiv/mol of thionin oxidized the fully-reduced enzyme to the point where A420 maximized. The four n = 1 redox sites which titrated in this region were designated group I sites. They include at least two iron-sulfur clusters, [Fe/S]A and [Fe/S]B, and two other sites, A' and B'. The [Fe4S4]2+/1+ cluster in CODH is included in this group. [Fe/S]B and B' have reduction potentials (at pH 8) below -480 mV vs NHE; [Fe/S]A and A' have reduction potentials above that value. The reduction potential of either [Fe/S]B or B' is near to the CO/CO2 couple at pH 8 (-622 mV). When CODH was oxidized by more than enough thionin to maximize A420, some of the excess thionin oxidized the so-called group II redox sites. These sites have reduction potentials more positive than group I and do not exhibit changes at 420 nm when titrated. Titration of group II sites required 1-2 equiv/mol. EPR of reduced group II sites exhibited the gav = 1.82 signal. When these sites were oxidized, the only signal present had g values at 2.075, 2.036, and 1.983.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Combination of Continuous Dexmedetomidine Infusion with Titrated Ultra-Low-Dose Propofol-Fentanyl for an Awake Craniotomy.

    PubMed

    Das, Samaresh; Al-Mashani, Ali; Suri, Neelam; Salhotra, Neeraj; Chatterjee, Nilay

    2016-08-01

    An awake craniotomy is a continuously evolving technique used for the resection of brain tumours from the eloquent cortex. We report a 29-year-old male patient who presented to the Khoula Hospital, Muscat, Oman, in 2016 with a two month history of headaches and convulsions due to a space-occupying brain lesion in close proximity with the left motor cortex. An awake craniotomy was conducted using a scalp block, continuous dexmedetomidine infusion and a titrated ultra-low-dose of propofolfentanyl. The patient remained comfortable throughout the procedure and the intraoperative neuropsychological tests, brain mapping and tumour resection were successful. This case report suggests that dexmedetomidine in combination with titrated ultra-low-dose propofolfentanyl are effective options during an awake craniotomy, ensuring optimum sedation, minimal disinhibition and a rapid recovery. To the best of the authors' knowledge, this is the first awake craniotomy conducted successfully in Oman. PMID:27606116

  18. Establishment of a national network of validated and qualified laboratories for neutralizing anti-vaccinia antibodies titration.

    PubMed

    Poirier, Bertrand; Leparc-Goffart, Isabelle; Crance, Jean-Marc; Fleury, Hervé; Garin, Daniel; Gut, Jean-Pierre; Tissier, Marie-Hélène; Fuchs, Florence

    2005-12-01

    A Proficiency Testing Study (PTS) was organized in France by the French Health Products Safety Agency (Afssaps) aiming at assessing the performance of laboratories in performing a neutralizing anti-vaccinia antibodies titration method by plaque reduction neutralization test (PRNT). The ultimate goal was to establish a national network of qualified and validated laboratories. Five laboratories were included in the PTS and four submitted their data. Three samples of human sera containing various immunoglobulin concentrations (a "high" serum: s-576, a "medium" serum: Ref-19584 and a "low" serum: s-483) were tested by PRNT as described in a procedure supplied by Afssaps and developed in each laboratory during preliminary assays. Data were sent to Afssaps which performed the statistical analysis. The overall performance of the four participating laboratories was satisfactory. This allowed the four participating laboratories to be validated and then to be qualified by the Ministry of Health. Finally a national network for anti-vaccinia immunoglobulins titration was established.

  19. Quantitative one-step RT-PCR assay for rapid and sensitive identification and titration of polioviruses in clinical specimens.

    PubMed

    Laassri, Majid; Dipiazza, Anthony; Bidzhieva, Bella; Zagorodnyaya, Tatiana; Chumakov, Konstantin

    2013-04-01

    Rapid identification and quantitation of polioviruses in clinical specimens is important for surveillance and analysis of virus shedding by vaccine recipients, which could be used to assess the level of mucosal immunity. A quantitative one step RT-PCR was developed for identification and titration of all three poliovirus serotypes. The assay could be an alternative to the traditional procedure based on cell culture isolation and subsequent determination of poliovirus serotype and virus titration. The method is based on quantitative PCR performed with reverse transcription reaction in the same tube. The multiplex assay that quantifies all three serotypes of poliovirus was found to be highly specific, sensitive, and takes only one day to complete.

  20. Combination of Continuous Dexmedetomidine Infusion with Titrated Ultra-Low-Dose Propofol-Fentanyl for an Awake Craniotomy

    PubMed Central

    Das, Samaresh; Al-Mashani, Ali; Suri, Neelam; Salhotra, Neeraj; Chatterjee, Nilay

    2016-01-01

    An awake craniotomy is a continuously evolving technique used for the resection of brain tumours from the eloquent cortex. We report a 29-year-old male patient who presented to the Khoula Hospital, Muscat, Oman, in 2016 with a two month history of headaches and convulsions due to a space-occupying brain lesion in close proximity with the left motor cortex. An awake craniotomy was conducted using a scalp block, continuous dexmedetomidine infusion and a titrated ultra-low-dose of propofolfentanyl. The patient remained comfortable throughout the procedure and the intraoperative neuropsychological tests, brain mapping and tumour resection were successful. This case report suggests that dexmedetomidine in combination with titrated ultra-low-dose propofolfentanyl are effective options during an awake craniotomy, ensuring optimum sedation, minimal disinhibition and a rapid recovery. To the best of the authors’ knowledge, this is the first awake craniotomy conducted successfully in Oman. PMID:27606116

  1. H, G1, G2 photometric phase function extended to low-accuracy data

    NASA Astrophysics Data System (ADS)

    Penttilä, A.; Shevchenko, V. G.; Wilkman, O.; Muinonen, K.

    2016-04-01

    We introduce a constrained nonlinear least-squares algorithm to be used in estimating the parameters in the H, G1, G2 phase function. As the algorithm works directly in the magnitude space, it will surpass the possible bias problem that may be present in the existing H ,G1 ,G2 fit procedure when applied to low-accuracy observations with large magnitude variations. With constraints on the photometric phase-curve shape parameters G1 and G2, it guarantees a physically reasonable phase-curve estimate. With a new data set of 93 asteroids, we re-assess the two-parameter version of the H ,G1 ,G2 function. Finally, we introduce a one-parameter version of the phase function that can give a suggestion of the asteroids taxonomic group based only on its phase curve. A statistical model selection procedure is presented that can automatically select between the different versions of the photometric phase functions. An online tool that implements these algorithms is introduced.

  2. Experimental parameters in the photometric analysis of uranium in TBP-dodecane solutions

    SciTech Connect

    Bostick, D.T.; Strain, J.E.

    1981-01-01

    A systematic study of the direct colorimetric determination of uranium in tributyl phosphate-dodecane solutions has been made. A number of parameters, including HNO{sub 3}, TBP, mono- and dibutyl phosphate concentrations, temperature, and extent of solvent degradation, have been investigated to determine what effect they have on the accuracy of uranium analysis. The procedure, based on the absorbance of UO{sub 2}(NO{sub 3}){sub 2}.2TBP at 416 nm, was found to be independent of HNO{sub 3} concentration and is not significantly affected by fluctuations in the concentration of TBP, MBP, and DBP under normal operating conditions. Phase separation occurs in hydrated organic samples at elevated temperatures; however, the accuracy of the photometric method is essentially independent of temperature fluctuations if the absorbance at 550 nm is used to correct 416-nm absorbance for sample opacity. Significant positive bias in assay results is observed in organic streams when spent TBP is recycled through the reprocessing facility. The absorbance from solvent coloration, produced by the presence of TBP nitrification products, must be subtracted from the total 416-nm absorbance to obtain an accurate analysis of uranium under these process conditions. The operating range of the procedure, using a 0.5-cm photometric cell, is 1 to 100 g/l U, with an estimated accuracy of +-0.5 g/l U.

  3. Electrophoretic separation of alginic sodium diester and sodium hexametaphosphate in chondroitin sulfate that interfere with the cetylpyridinium chloride titration assay.

    PubMed

    Weiguo, Zhang; Giancaspro, Gabriel; Adams, Kristie M; Neal-Kababick, James; Hildreth, Jana; Li, Aishan; Roman, Mark C; Betz, Joseph M

    2014-01-01

    adulterants in CS and procedures to isolate ASD from CS matrixes containing these adulterants. The authors describe in this paper utilization of an orthogonal approach to establish the identity of Z1 as sodium hexametaphosphate and to confirm the identity of ASD, including ethanol fractionation, FTIR spectroscopy, differential scanning calorimetry, and NMR spectroscopy. The authors suggest that CAME is a cost-effective and easy to use methodfor detecting certain impurities in CS raw ingredients and recommend that CPC and CAME be used in combination by QC laboratories as a means of effectively deterring the practice of adulterating CS raw materials with the known adulterants ASD and Z1 and/or other non-chondroitin substances that can be separated from CSby CAME and that exhibit CPC titration behavior similar to CS.

  4. Electrophoretic separation of alginic sodium diester and sodium hexametaphosphate in chondroitin sulfate that interfere with the cetylpyridinium chloride titration assay.

    PubMed

    Weiguo, Zhang; Giancaspro, Gabriel; Adams, Kristie M; Neal-Kababick, James; Hildreth, Jana; Li, Aishan; Roman, Mark C; Betz, Joseph M

    2014-01-01

    adulterants in CS and procedures to isolate ASD from CS matrixes containing these adulterants. The authors describe in this paper utilization of an orthogonal approach to establish the identity of Z1 as sodium hexametaphosphate and to confirm the identity of ASD, including ethanol fractionation, FTIR spectroscopy, differential scanning calorimetry, and NMR spectroscopy. The authors suggest that CAME is a cost-effective and easy to use methodfor detecting certain impurities in CS raw ingredients and recommend that CPC and CAME be used in combination by QC laboratories as a means of effectively deterring the practice of adulterating CS raw materials with the known adulterants ASD and Z1 and/or other non-chondroitin substances that can be separated from CSby CAME and that exhibit CPC titration behavior similar to CS. PMID:25372663

  5. Phosphorus-doped and undoped glassy carbon indicator electrodes in controlled-current potentiometric titrations of bromide- or chloride-containing active ingredients in some pharmaceutical preparations.

    PubMed

    Abramović, Biljana F; Guzsvány, Valéria J; Gaál, Ferenc F

    2005-02-23

    Phosphorus-doped glassy carbon (as a novel material) and glassy carbon (Sigri commercial sample) were applied as potentiometric indicator electrodes in the titrimetric determination of active components with bromide or chloride in their molecules in different pharmaceutical preparations (Buscopan, Prostigmine, Isoptin, Bedoxin, Akineton and Trodon). After the necessary pre-treatment of the electrode surfaces and sample dissolution, the halide was titrated with a standard solution of silver nitrate (indirect determination). Amounts of 10-20 micromol of the investigated active ingredients per titration were determined with a relative standard deviation that, depending on the nature of indicator electrode, determined molecules and filler components, was in the range of 0.3-2.7%. The results obtained were compared with those of the official methods and with those obtained by potentiometric titrations using silver electrode. The titrimetric procedures developed are relatively fast, easy, economical and can be used to analyse of a large number of pharmaceutical products.

  6. Photometric Calibrators for the Second-Generation Palomar Sky Surveys

    NASA Astrophysics Data System (ADS)

    McLean, Brian; Bucciarelli, Beatrice; Garcia Yus, Jorge; Loomis, Charles; Alessandro, Spagna; Greene, Gretchen

    2006-08-01

    The latest GSC-II release (GSC2.3) includes positions, proper motions, photographic photometry (blue J, red F and near-IR N), and star/non-star classification of nearly 1 billion objects to a limiting magnitude of J~eq 22 and F~eq 20.5. Besides its obvious applications for telescope operations and space missions planning, the all-sky astro-photometric properties of GSC-II make it a highly valuable tool for a wide range of astrophysical investigations and data mining. A major effort toward the construction of such a catalog has been the collection of ad-hoc photometric sequences (a total of ~ 1780) for the linearization of the density-to-intensity response of each survey plate; this is summarized by the realization of the CCD-based, photometric catalogue GSPC-II. More details on the GSC- II and GSPC-II, and their releases, can bee found at www- gsss.stsci.edu/Catalogs/Catalogs.htm With this proposal we are addressing the remaining 100 fields still lacking photometric calibrators. Eighty of them were targets of a previous KPNO proposal (ID 2005B-0139), but did not get proper data due to uncooperative weather; most of the twenty southern sequences need re- observations because they are of poor photometric quality.

  7. On differential photometric reconstruction for unknown, isotropic BRDFs.

    PubMed

    Chandraker, Manmohan; Bai, Jiamin; Ramamoorthi, Ravi

    2013-12-01

    This paper presents a comprehensive theory of photometric surface reconstruction from image derivatives in the presence of a general, unknown isotropic BRDF. We derive precise topological classes up to which the surface may be determined and specify exact priors for a full geometric reconstruction. These results are the culmination of a series of fundamental observations. First, we exploit the linearity of chain rule differentiation to discover photometric invariants that relate image derivatives to the surface geometry, regardless of the form of isotropic BRDF. For the problem of shape-from-shading, we show that a reconstruction may be performed up to isocontours of constant magnitude of the gradient. For the problem of photometric stereo, we show that just two measurements of spatial and temporal image derivatives, from unknown light directions on a circle, suffice to recover surface information from the photometric invariant. Surprisingly, the form of the invariant bears a striking resemblance to optical flow; however, it does not suffer from the aperture problem. This photometric flow is shown to determine the surface up to isocontours of constant magnitude of the surface gradient, as well as isocontours of constant depth. Further, we prove that specification of the surface normal at a single point completely determines the surface depth from these isocontours. In addition, we propose practical algorithms that require additional initial or boundary information, but recover depth from lower order derivatives. Our theoretical results are illustrated with several examples on synthetic and real data.

  8. Photometric redshifts for the SDSS Data Release 12

    NASA Astrophysics Data System (ADS)

    Beck, Róbert; Dobos, László; Budavári, Tamás; Szalay, Alexander S.; Csabai, István

    2016-08-01

    We present the methodology and data behind the photometric redshift data base of the Sloan Digital Sky Survey (SDSS) Data Release 12. We adopt a hybrid technique, empirically estimating the redshift via local regression on a spectroscopic training set, then fitting a spectrum template to obtain K-corrections and absolute magnitudes. The SDSS spectroscopic catalogue was augmented with data from other, publicly available spectroscopic surveys to mitigate target selection effects. The training set is comprised of 1976 978 galaxies, and extends up to redshift z ≈ 0.8, with a useful coverage of up to z ≈ 0.6. We provide photometric redshifts and realistic error estimates for the 208 474 076 galaxies of the SDSS primary photometric catalogue. We achieve an average bias of overline{Δ z_{norm}} = {5.84 × 10^{-5}}, a standard deviation of σ(Δznorm) = 0.0205, and a 3σ outlier rate of Po = 4.11 per cent when cross-validating on our training set. The published redshift error estimates and photometric error classes enable the selection of galaxies with high-quality photometric redshifts. We also provide a supplementary error map that allows additional, sophisticated filtering of the data.

  9. Morphology classification and photometric redshift measurement of galaxies

    NASA Astrophysics Data System (ADS)

    Zhang, Yanxia; Li, Lili; Zhao, Yongheng

    2009-01-01

    Based on the Sloan Digital Sky Survey Data Release 5 Galaxy Sample, we explore photometric morphology classification and redshift estimation of galaxies using photometric data and known spectroscopic redshifts. An unsupervised method, k-means algorithm, is used to separate the whole galaxy sample into early- and late-type galaxies. Then, we investigate the photometric redshift measurement with different input patterns by means of artificial neural networks (ANNs) for the total sample and two subsamples. The experimental result indicates that ANNs show better performance when more parameters are applied in the training set, and the mixed accuracy of photometric redshift estimation for the two subsets is superior to σz for the overall sample alone. For the optimal result, the rms deviation of photometric redshifts for the mixed sample amounts to 0.0192, that for the overall sample is 0.0196, meanwhile, that for early- and late-type galaxies adds up to 0.0164 and 0.0217, respectively.

  10. Automated potentiometric titrations in KCl/water-saturated octanol: method for quantifying factors influencing ion-pair partitioning.

    PubMed

    Scherrer, Robert A; Donovan, Stephen F

    2009-04-01

    The knowledge base of factors influencing ion pair partitioning is very sparse, primarily because of the difficulty in determining accurate log P(I) values of desirable low molecular weight (MW) reference compounds. We have developed a potentiometric titration procedure in KCl/water-saturated octanol that provides a link to log P(I) through the thermodynamic cycle of ionization and partitioning. These titrations have the advantage of being independent of the magnitude of log P, while maintaining a reproducibility of a few hundredths of a log P in the calculated difference between log P neutral and log P ion pair (diff (log P(N - I))). Simple model compounds can be used. The titration procedure is described in detail, along with a program for calculating pK(a)'' values incorporating the ionization of water in octanol. Hydrogen bonding and steric factors have a greater influence on ion pairs than they do on neutral species, yet these factors are missing from current programs used to calculate log P(I) and log D. In contrast to the common assumption that diff (log P(N - I)) is the same for all amines, they can actually vary more than 3 log units, as in our examples. A major factor affecting log P(I) is the ability of water and the counterion to approach the charge center. Bulky substituents near the charge center have a negative influence on log P(I). On the other hand, hydrogen bonding groups near the charge center have the opposite effect by lowering the free energy of the ion pair. The use of this titration method to determine substituent ion pair stabilization values (IPS) should bring about more accurate log D calculations and encourage species-specific QSAR involving log D(N) and log D(I). This work also brings attention to the fascinating world of nature's highly stabilized ion pairs.

  11. Development of a novel baculovirus titration method using the Enzyme-linked immunosorbent spot (ELISPOT) assay.

    PubMed

    Wang, Wei; Cheng, Tong; Ma, Ke; Xia, Dezhen; Wang, Yongmei; Liu, Jian; Du, Hailian; Shih, James Wai Kuo; Zhang, Jun; Zhao, Qinjian; Xia, Ningshao

    2013-03-01

    The baculovirus expression vector system (BEVS) is one of the most powerful methods for production of recombinant proteins for research or commercial purposes. Titration of viable virus in insect cell culture is often required when BEVS is used for basic research or bioprocessing. An enzyme-linked immunosorbent spot (ELISPOT) assay using monoclonal antibodies against the major capsid protein VP39 of both Autographa californica nuclear polyhedrosis virus (AcMNPV) and Bombyx mori nuclear polyhedrosis virus (BmNPV) was developed for baculovirus quantitation at 48h post-infection. The titer was determined by visualizing infected insect cells as blue spots and automated spot counting was achieved with ELISPOT hardware and software. Log-scale comparison of the results between the ELISPOT assay and a conventional end point dilution assay using a fluorescent marker showed a good correlation for both AcMNPV (R(2)=0.9980, p<0.05) and BmNPV (R(2)=0.9834, p<0.05). In conclusion, a novel, rapid and semi-automated procedure for titrating baculovirus was developed based on the specific immunostaining of infected cells followed by automated spot counting.

  12. Solution Equilibrium Titration for High-Throughput Affinity Estimation of Unpurified Antibodies and Antibody Fragments.

    PubMed

    Della Ducata, Daniela; Jaehrling, Jan; Hänel, Cornelia; Satzger, Marion; Wolber, Meike; Ostendorp, Ralf; Pabst, Stefan; Brocks, Bodo

    2015-12-01

    The generation of therapeutic antibodies with extremely high affinities down to the low picomolar range is today feasible with state-of-the art recombinant technologies. However, reliable and efficient identification of lead candidates with the desired affinity from a pool of thousands of antibody clones remains a challenge. Here, we describe a high-throughput procedure that allows reliable affinity screening of unpurified immunoglobulin G or antibody fragments. The method is based on the principle of solution equilibrium titration (SET) using highly sensitive electrochemiluminescence as a readout system. Because the binding partners are not labeled, the resulting KD represents a sound approximation of the real affinity. For screening, diluted bacterial lysates or cell culture supernatants are equilibrated with four different concentrations of a soluble target molecule, and unbound antibodies are subsequently quantified on 384-well Meso Scale Discovery (MSD) plates coated with the respective antigen. For determination of KD values from the resulting titration curves, fit models deduced from the law of mass action for 1:1 and 2:1 binding modes are applied to assess hundreds of interactions simultaneously. The accuracy of the method is demonstrated by comparing results from different screening campaigns from affinity optimization projects with results from detailed affinity characterization.

  13. [Titration of Ebola and Marburg viruses by plaque formation under semi liquid agar].

    PubMed

    Ustinova, E N; Shestopalov, A M; Bakulina, L F; Chepurnov, A A

    2003-01-01

    The method of titration of Ebola and Marburg viruses using plaque formation under semifluid agar cover is considered. Advantages of this method over conventional method of titration of these viruses with the use of hard agar cover are discussed.

  14. Development and optimization of a real-time quantitative PCR-based method for the titration of AAV-2 vector stocks.

    PubMed

    Veldwijk, Marlon R; Topaly, Julian; Laufs, Stephanie; Hengge, Ulrich R; Wenz, Frederik; Zeller, W Jens; Fruehauf, Stefan

    2002-08-01

    Despite the clinical application of adeno-associated virus (AAV) gene therapy, the titration of viral stocks has not yet been standardized. This complicates the comparison of viral stocks between laboratories. Functional titering of AAV is time-consuming, requires the manipulation of hazardous material, and often has a high degree of variability. We established an optimized real-time quantitative polymerase chain reaction (RQ-PCR) titration assay to determine viral titers and compared it with a functional green fluorescent protein (GFP)-based titration method. With a combination of improved lysis procedures and RQ-PCR protocols we could decrease the intraexperimental coefficient of variation (CV) from 0.24 +/- 0.03 to 0.042 +/- 0.004 and the interexperimental CV from 0.34 +/- 0.06 to 0.093 +/- 0.028 following functional and RQPCR-based titration, respectively. This low variability conforms to even the strictest quality standards required, for example, in clinical laboratories. The highly standardized titration by RQPCR described here will be especially advantageous for groups working on AAV-based gene therapy in a good manufacturing practice setting.

  15. Photometric Calibration of Consumer Video Cameras

    NASA Technical Reports Server (NTRS)

    Suggs, Robert; Swift, Wesley, Jr.

    2007-01-01

    Equipment and techniques have been developed to implement a method of photometric calibration of consumer video cameras for imaging of objects that are sufficiently narrow or sufficiently distant to be optically equivalent to point or line sources. Heretofore, it has been difficult to calibrate consumer video cameras, especially in cases of image saturation, because they exhibit nonlinear responses with dynamic ranges much smaller than those of scientific-grade video cameras. The present method not only takes this difficulty in stride but also makes it possible to extend effective dynamic ranges to several powers of ten beyond saturation levels. The method will likely be primarily useful in astronomical photometry. There are also potential commercial applications in medical and industrial imaging of point or line sources in the presence of saturation.This development was prompted by the need to measure brightnesses of debris in amateur video images of the breakup of the Space Shuttle Columbia. The purpose of these measurements is to use the brightness values to estimate relative masses of debris objects. In most of the images, the brightness of the main body of Columbia was found to exceed the dynamic ranges of the cameras. A similar problem arose a few years ago in the analysis of video images of Leonid meteors. The present method is a refined version of the calibration method developed to solve the Leonid calibration problem. In this method, one performs an endto- end calibration of the entire imaging system, including not only the imaging optics and imaging photodetector array but also analog tape recording and playback equipment (if used) and any frame grabber or other analog-to-digital converter (if used). To automatically incorporate the effects of nonlinearity and any other distortions into the calibration, the calibration images are processed in precisely the same manner as are the images of meteors, space-shuttle debris, or other objects that one seeks to

  16. Extraction preconcentration and photometric determination of chlorophenols and naphthols in aqueous media

    SciTech Connect

    Korenman, Ya.I.; Kalinkina, S.P.; Sukhanov, P.T.

    1994-11-01

    Mono- and bicyclic hydroxy compounds (phenol, chlorophenols, naphthols, and naphtholsulfonic acids) are industrial toxicants; these compounds occur in waste water from the production of dyestuffs, polymer materials, perfumes, drugs, varnishes, paints, and pesticides. Phenol, chlorophenols, and naphthols are carcinogenic toxicants; they may constitute a threat to living organisms in reservoirs and biologically active silts. The presence of these compounds changes the oxygen balance of water basins. The maximum permissible concentration of these compounds in water varies from 10{sup {minus}1} (naphthols) to 10{sup {minus}4} mg/L (chlorophenols). For the reliable determination of microquantities of toxicants in water, we proposed procedures that include extraction by lower alcohols, organic acids, and hexane or hexane-hexanol solutions of solvotropic reagents (dialkyl phthalates and trialkyl phthalates). A set of extraction photometric procedures has been developed for the total and selective determination of microquantities of phenol and naphthol toxicants in aqueous media.

  17. ANNz: Estimating Photometric Redshifts Using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Collister, Adrian A.; Lahav, Ofer

    2004-04-01

    We introduce ANNz, a freely available software package for photometric redshift estimation using artificial neural networks. ANNz learns the relation between photometry and redshift from an appropriate training set of galaxies for which the redshift is already known. Where a large and representative training set is available, ANNz is a highly competitive tool when compared with traditional template-fitting methods. The ANNz package is demonstrated on the Sloan Digital Sky Survey Data Release 1, and for this particular data set the rms redshift error in the range 0<~z<~0.7 is σrms=0.023. Nonideal conditions (spectroscopic sets that are small or brighter than the photometric set for which redshifts are required) are simulated, and the impact on the photometric redshift accuracy is assessed.2

  18. First photometric study of W UMa binary star LU Lac

    NASA Astrophysics Data System (ADS)

    Liao, W.-P.; Qian, S.-B.; Zhao, E.-G.; Jiang, L.-Q.

    2014-08-01

    LU Lac is a neglected W UMa binary star in photometric investigations. In this paper, we present BVRI CCD photometric light curves obtained on one night in 2012. The first photometric solutions of this system are computed by using the Wilson-Devinney code. It is shown that LU Lac is a marginal contact W-type system with a degree of contact factor of f=8.9%, a mass ratio of q=2.085 and a high inclination of i=82°.20. From the first analyses of orbital period changes, we found the period variation of the system includes an oscillation (A3=0.0125 days and T3=51.92 years). The cyclic change may be attributed to the light-travel time effect through the presence of a third body.

  19. Photometric Analysis in the Kepler Science Operations Center Pipeline

    NASA Technical Reports Server (NTRS)

    Twicken, Joseph D.; Clarke, Bruce D.; Bryson, Stephen T.; Tenenbaum, Peter; Wu, Hayley; Jenkins, Jon M.; Girouard, Forrest; Klaus, Todd C.

    2010-01-01

    We describe the Photometric Analysis (PA) software component and its context in the Kepler Science Operations Center (SOC) pipeline. The primary tasks of this module are to compute the photometric flux and photocenters (centroids) for over 160,000 long cadence (thirty minute) and 512 short cadence (one minute) stellar targets from the calibrated pixels in their respective apertures. We discuss the science algorithms for long and short cadence PA: cosmic ray cleaning; background estimation and removal; aperture photometry; and flux-weighted centroiding. We discuss the end-to-end propagation of uncertainties for the science algorithms. Finally, we present examples of photometric apertures, raw flux light curves, and centroid time series from Kepler flight data. PA light curves, centroid time series, and barycentric timestamp corrections are exported to the Multi-mission Archive at Space Telescope [Science Institute] (MAST) and are made available to the general public in accordance with the NASA/Kepler data release policy.

  20. Spectral reflectance and photometric properties of selected rocks

    USGS Publications Warehouse

    Watson, Robert D.

    1971-01-01

    Studies of the spectral reflectance and photometric properties of selected rocks at the USGS Mill Creek, Oklahoma, remote sensing test site demonstrate that discrimination of rock types is possible through reflection measurements, but that the discrimination is complicated by surface conditions, such as weathering and lichen growth. Comparisons between fresh-broken, weathered, and lichen-covered granite show that whereas both degree of weathering and amount of lichen cover change the reflectance quality of the granite, lichen cover also considerably changes the photometric properties of the granite. Measurements of the spectral reflectance normal to the surface of both limestone and dolomite show limestone to be more reflective than dolomite in the wavelength range from 380 to 1550 nanometers. The reflectance difference decreases at view angles greater than 40° owing to the difference in the photometric properties of dolomite and limestone.

  1. Nile blue and brilliant cresyl blue as redox indicators in iron(II) titrations.

    PubMed

    Sriramam, K

    1975-01-01

    Nile Blue and Brilliant Cresyl Blue, two compounds related to diaminophenoxazine, have been studied as indicators in titrations of iron(II) with cerium(IV)(in hydrochloric, sulphuric and perchloric acid media), dichromate, vanadate and permanganate. They are particularly suited for titrations in a fairly concentrated sulphuric acid medium and for titrations with dilute solutions. A probable indicator mechanism is suggested.

  2. The Acid-Base Titration of a Very Weak Acid: Boric Acid

    ERIC Educational Resources Information Center

    Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V.

    2012-01-01

    A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…

  3. Comparision of approaches to photometric redshift estimation of quasars

    NASA Astrophysics Data System (ADS)

    Tu, Yang; Zhang, Yanxia; Zhao, Yongheng; Tian, Haijun

    2015-08-01

    Based on databases from various different band photometric surveys (optical from SDSS, infrared from UKIDSS and WISE), we compare k-nearest neighbor regression based on KD-tree and Ball-tree, LASSO, PLS (Partial Least Squares), SDG, ridge regression and kernel ridge regression applied for photometric redshift estimation of quasars. The experimental result shows that the perfomance order of these methods is KD-tree kNN, Ball-tree kNN, kernal ridge regression, ridge regression, PLS, SGD, LASSO.

  4. Photometric measurements of solar irradiance variations due to sunspots

    NASA Technical Reports Server (NTRS)

    Chapman, G. A.; Herzog, A. D.; Laico, D. E.; Lawrence, J. K.; Templer, M. S.

    1989-01-01

    A photometric telescope constructed to obtain photometric sunspot areas and deficits on a daily basis is described. Data from this Cartesian full disk telescope (CFDT) are analyzed with attention given to the period between June 4 and June 17, 1985 because of the availability of overlapping sunspot area and irradiance deficit data from high-resolution digital spectroheliograms made with the San Fernando Observatory 28 cm vacuum solar telescope and spectroheliograph. The CFDT sunspot deficits suggest a substantial irradiance contribution from faculae and active region plage.

  5. Titration of vaccinia virus by intravenous injection of chick embryos.

    PubMed

    KAPLAN, C

    1960-01-01

    The final test of a smallpox vaccine is its capacity to prevent the disease from developing in inoculated individuals. This capacity, however, cannot be measured directly, so that other methods of assessing the efficacy of vaccine have had to be developed. A laboratory method-pock counting on the chorio-allantoic membrane of chick embryos-has recently been shown to provide a reasonably reliable estimate of the number of infective units in a given vaccine. In this paper, the author compares this pock-counting method with another method-titration by intravenous injection of chick embryos. He concludes that, although the reproducibility of titrations by intravenous injection compares very favourably with that obtained by chorio-allantoic inoculation, the former method would not be advantageous for the assay of vaccines, since it is very time-consuming and since differences in virulence might obscure comparisons between the efficacy of vaccines.

  6. High-throughput titration of luciferase-expressing recombinant viruses.

    PubMed

    Garcia, Vanessa; Krishnan, Ramya; Davis, Colin; Batenchuk, Cory; Le Boeuf, Fabrice; Abdelbary, Hesham; Diallo, Jean-Simon

    2014-01-01

    Standard plaque assays to determine infectious viral titers can be time consuming, are not amenable to a high volume of samples, and cannot be done with viruses that do not form plaques. As an alternative to plaque assays, we have developed a high-throughput titration method that allows for the simultaneous titration of a high volume of samples in a single day. This approach involves infection of the samples with a Firefly luciferase tagged virus, transfer of the infected samples onto an appropriate permissive cell line, subsequent addition of luciferin, reading of plates in order to obtain luminescence readings, and finally the conversion from luminescence to viral titers. The assessment of cytotoxicity using a metabolic viability dye can be easily incorporated in the workflow in parallel and provide valuable information in the context of a drug screen. This technique provides a reliable, high-throughput method to determine viral titers as an alternative to a standard plaque assay.

  7. Applications of isothermal titration calorimetry in protein science.

    PubMed

    Liang, Yi

    2008-07-01

    During the past decade, isothermal titration calorimetry (ITC) has developed from a specialist method for understanding molecular interactions and other biological processes within cells to a more robust, widely used method. Nowadays, ITC is used to investigate all types of protein interactions, including protein-protein interactions, protein-DNA/RNA interactions, protein-small molecule interactions and enzyme kinetics; it provides a direct route to the complete thermodynamic characterization of protein interactions. This review concentrates on the new applications of ITC in protein folding and misfolding, its traditional application in protein interactions, and an overview of what can be achieved in the field of protein science using this method and what developments are likely to occur in the near future. Also, this review discusses some new developments of ITC method in protein science, such as the reverse titration of ITC and the displacement method of ITC.

  8. [The use of tapioca as coverage in viral titration].

    PubMed

    Post, P R; de Carvalho, R; Brito, E C; Galler, R

    1992-01-01

    Virus titration is an important step required on viral vaccines quality control. "Plaque assay", which employs several types of overlay media, is usually used on viral titrations. In this paper we describe the use of Tapioca as an overlay media. Firstly, the toxicity of Tapioca was tested on Vero cells inoculated or not with the Yellow Fever virus (YF) 17DD vaccine strain. Secondly, different batches of the 17DD virus using the Tapioca and Karaya gum as the overlay on Vero cells were tested when higher titres were obtained using Tapioca. Tapioca was also shown to be a suitable overlay to be used in thermostability and plaque reduction neutralization tests. Other systems could benefit from the use of Tapioca as an overlay, since it was possible to titer Measles virus in Vero cells. Tapioca is a cheap Brazilian product, is locally available, easy to use, and reliable. Its use is suggested.

  9. Semi-automated potentiometric titration method for uranium characterization.

    PubMed

    Cristiano, B F G; Delgado, J U; da Silva, J W S; de Barros, P D; de Araújo, R M S; Lopes, R T

    2012-07-01

    The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization.

  10. Impact of Residual Inducer on Titratable Expression Systems

    PubMed Central

    Afroz, Taliman; Luo, Michelle L.; Beisel, Chase L.

    2015-01-01

    Inducible expression systems are widely employed for the titratable control of gene expression, yet molecules inadvertently present in the growth medium or synthesized by the host cells can alter the response profile of some of these systems. Here, we explored the quantitative impact of these residual inducers on the apparent response properties of inducible systems. Using a simple mathematical model, we found that the presence of residual inducer shrinks the apparent dynamic range and causes the apparent Hill coefficient to converge to one. We also found that activating systems were more sensitive than repressing systems to the presence of residual inducer and the response parameters were most heavily dependent on the original Hill coefficient. Experimental interrogation of common titratable systems based on an L-arabinose inducible promoter or a thiamine pyrophosphate-repressing riboswitch in Escherichia coli confirmed the predicted trends. We finally found that residual inducer had a distinct effect on “all-or-none” systems, which exhibited increased sensitivity to the added inducer until becoming fully induced. Our findings indicate that residual inducer or repressor alters the quantitative response properties of titratable systems, impacting their utility for scientific discovery and pathway engineering. PMID:26348036

  11. Titration behaviour of three strains of tobacco mosaic virus.

    PubMed

    Hendry, D A; Durham, A C

    1980-01-15

    Hydrogen ion titration curves of the virions and proteins of three strains of tobacco mosaic virus (Y-TAMV, U2, and cowpea) were measured in the absence and the presence of Ca2+, Mg2+, or Mn2+ ions, and compared with the analogous curves for the type strain (vulgare). Extinction coefficients were also measured for all four strains' virions and proteins. Y-TAMV is very like vulgare in its cation affinities: the virion has probably three groups per protein subunit that titrate near neutral pH and significantly bind metal ions; the RNA-free protein has very little affinity for Ca2+, although moderate Ca2+ concentrations favour the existence of larger polymers. U2 and cowpea strain virions bind cations significantly more strongly than do Y-TAMV or vulgare virions: their polymerized proteins, too, have significant affinities for Ca2+ ions, which make their titration and sedimentation behaviours relatively sensitive to added calcium. These cation-binding differences correspond well with the differences between the strains' protein sequences. The features common to all four strains are that the virions are apparently structurally invariant and have at least one site per subunit with Ca2+ affinity in the region of 10(-5)M, while the RNA-free proteins lack the high-affinity sites but have weaker Ca2+ affinities in the region of 10(-3)M. Some of the cation-binding sites probably lie near the central holes of the virions.

  12. New methods to titrate EIAV-based lentiviral vectors.

    PubMed

    Martin-Rendon, Enca; White, Linda J; Olsen, Anna; Mitrophanous, Kyriacos A; Mazarakis, Nicholas D

    2002-05-01

    Ideally, gene transfer vectors used in clinical protocols should only express the gene of interest. So far most vectors have contained marker genes to aid their titration. We have used quantitative real-time PCR to titrate equine infectious anemia virus (EIAV) vectors for gene therapy applications. Viral RNA was isolated from vector preparations and analyzed in a one-step RT-PCR reaction in which reverse transcription and amplification were combined in one tube. The PCR assay of vector stocks was quantitative and linear over four orders of magnitude. In tandem, the integration efficiency of these vectors has also been determined by real-time PCR, measuring the number of vector genomes in the target cells. We have found that these methods permit reliable and sensitive titration of lentiviral vectors independent from the expression of a transgene. They also allow us to determine the integration efficiency of different vector genomes. This technology has proved very useful, especially in the absence of marker genes and where vectors express multiple genes.

  13. Suspension culture titration: A simple method for measuring baculovirus titers.

    PubMed

    Matindoost, Leila; Chan, Leslie C L; Qi, Ying Mei; Nielsen, Lars K; Reid, Steven

    2012-08-01

    The baculovirus-insect cell expression system is an important technology for the production of recombinant proteins and baculovirus-based biopesticides. Budded virus titration is critical when scaling up baculovirus production processes in suspension cultures, to ensure reproducible infections, especially when a low multiplicity of infection (MOI) is applied. In this study, a simple suspension culture titration (SCT) assay was developed that involves accurate measurements of the initial cell densities (ICDs) and peak cell densities (PCDs) of an infected culture, from which the MOI and hence the virus inoculum infectious titer can be estimated, using the established Power-Nielsen baculovirus infection model. The SCT assay was assessed in parallel with two adherent culture-based assays (MTT and AlamarBlue) for the Heliothine baculovirus HaSNPV, and was shown to be more objective, time-efficient and reproducible. The model predicted a linear correlation between log(PCD/ICD) and log(MOI), hence an alternative model-independent SCT assay was also developed, which relies on a well-replicated standard curve relating suspension culture-derived PCD/ICD ratios with plaque or endpoint assay-derived MOIs. Standard curves with excellent linearity were generated for HaSNPV and the industrially significant rAcMNPV, demonstrating the feasibility of this simple titration approach, especially in terms of its applicability to a wide range of virus infection kinetics.

  14. Impact of Residual Inducer on Titratable Expression Systems.

    PubMed

    Afroz, Taliman; Luo, Michelle L; Beisel, Chase L

    2015-01-01

    Inducible expression systems are widely employed for the titratable control of gene expression, yet molecules inadvertently present in the growth medium or synthesized by the host cells can alter the response profile of some of these systems. Here, we explored the quantitative impact of these residual inducers on the apparent response properties of inducible systems. Using a simple mathematical model, we found that the presence of residual inducer shrinks the apparent dynamic range and causes the apparent Hill coefficient to converge to one. We also found that activating systems were more sensitive than repressing systems to the presence of residual inducer and the response parameters were most heavily dependent on the original Hill coefficient. Experimental interrogation of common titratable systems based on an L-arabinose inducible promoter or a thiamine pyrophosphate-repressing riboswitch in Escherichia coli confirmed the predicted trends. We finally found that residual inducer had a distinct effect on "all-or-none" systems, which exhibited increased sensitivity to the added inducer until becoming fully induced. Our findings indicate that residual inducer or repressor alters the quantitative response properties of titratable systems, impacting their utility for scientific discovery and pathway engineering. PMID:26348036

  15. Protometric thermometric titrations of sparingly soluble compounds in water in the presence of n-octanol.

    PubMed

    Burgot, G; Burgot, J-L

    2002-10-15

    Thermometric titrimetry permits titration of acido-basic compounds in water in the presence of n-octanol. n-Octanol permits the solubilization of protolytes and moreover may also displace the equilibria of the titration reactions. Hydrochlorides of highly insoluble derivatives such as phenothiazine derivatives can be titrated with satisfactory accuracy and precision by sodium hydroxide despite their high pK(a) values. Likewise barbiturate salts can be titrated by hydrochloric acid. In the case of some salts, the methodology may permit the sequential titration of the ion and counter ion.

  16. Sensitivity of the acid-base properties of clays to the methods of preparation and measurement. 2. Evidence from continuous potentiometric titrations.

    PubMed

    Duc, Myriam; Gaboriaud, Fabien; Thomas, Fabien

    2005-09-01

    The effects of experimental procedures on the acid-base consumption titration curves of montmorillonite suspension were studied using continuous potentiometric titration. For that purpose, the hysteresis amplitudes between the acid and base branches were found to be useful to systematically evaluate the impacts of storage conditions (wet or dried), the atmosphere in titration reactor, the solid-liquid ratio, the time interval between successive increments, and the ionic strength. In the case of storage conditions, the increase of the hysteresis was significantly higher for longer storage of clay in suspension and drying procedures compared to "fresh" clay suspension. The titration carried out under air demonstrated carbonate contamination that could only be cancelled by performing experiments under inert gas. Interestingly, the increase of the time intervals between successive increments of titrant strongly emphasized the amplitude of hysteresis, which could be correlated with the slow kinetic process specifically observed for acid addition in acid media. Thus, such kinetic behavior is probably associated with dissolution processes of clay particles. However, the resulting curves recorded at different ionic strengths under optimized conditions did not show the common intersection point required to define point of zero charge. Nevertheless, the ionic strength dependence of the point of zero net proton charge suggested that the point of zero charge of sodic montmorillonite could be estimated as lower than 5.

  17. SHARDS: AN OPTICAL SPECTRO-PHOTOMETRIC SURVEY OF DISTANT GALAXIES

    SciTech Connect

    Perez-Gonzalez, Pablo G.; Cava, Antonio; Barro, Guillermo; Villar, Victor; Cardiel, Nicolas; Espino, Nestor; Gallego, Jesus; Ferreras, Ignacio; Rodriguez-Espinosa, Jose Miguel; Balcells, Marc; Cepa, Jordi; Alonso-Herrero, Almudena; Cenarro, Javier; Charlot, Stephane; Cimatti, Andrea; Conselice, Christopher J.; Daddi, Emmanuele; Elbaz, David; Gobat, R. [Laboratoire AIM-Paris-Saclay, CEA and others

    2013-01-01

    We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin{sup 2} at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R {approx} 50). The data reach an AB magnitude of 26.5 (at least at a 3{sigma} level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate- and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z > 1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z = 0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0 < z {approx}< 1.4. We discuss the improvements introduced by the SHARDS data set in the analysis of their star formation history and stellar properties. We discuss the systematics arising from the use of different stellar population libraries, typical in this kind of study. Averaging the results from the different libraries, we find that the UV-to-MIR SEDs of the massive quiescent galaxies at z = 1

  18. Comparison of Approaches to Photometric Redshift Estimation of Quasars

    NASA Astrophysics Data System (ADS)

    Tu, Yang; Zhang, Yan-Xia; Zhao, Yong-Heng; Tian, Hai-Jun

    We probe many kinds of approaches used for photometric redshift estimation of quasars, including KNN (K-nearest neighbor algorithm), Lasso (Least Absolute Shrinkage and Selection Operator), PLS (Partial Least Square regression), ridge regression, SGD (Stochastic Gradient Descent) and Extra-Trees.

  19. Photometric study of the peculiar galaxy NGC 2685

    SciTech Connect

    Gagen-Torn, V.A.; Popov, I.I.; Iakovleva, V.A.

    1984-04-01

    The results are given of detailed UBV photometry of the peculiar galaxy NGC 2685 based on 10 negatives obtained with the 2.6-m telescope of the Biurakan Observatory. Consideration of all the available observational data (photometric, spectroscopic, and polarization) suggests that NGC 2685 is a pair of colliding galaxies. 18 references.

  20. The ALHAMBRA survey: Accurate photometric merger fractions from PDF analysis

    NASA Astrophysics Data System (ADS)

    López-Sanjuan, C.; Cenarro, A. J..; Varela, J.; Viironen, K.; ALHAMBRA Team

    2015-05-01

    The estimation of the merger fraction in photometric surveys is limited by the large uncertainty in the photometric redshift compared with the velocity difference in kinematical close pairs (less than 500 km s^{-1}). Several efforts have conducted to deal with this limitation and we present the latest improvements. Our new method (i) provides a robust estimation of the merger fraction by using full probability distribution functions (PDFs) instead of Gaussian distributions, as in previous work; (ii) takes into account the dependence of the luminosity on redshift in both the selection of the samples and the definition of major/minor mergers; and (iii) deals with partial PDFs to define ``red" (E/S0 templates) and ``blue" (spiral/starburst templates) samples without apply any colour selection. We highlight our new method with the estimation of the merger fraction at z < 1 in the ALHAMBRA photometric survey. We find that our merger fractions and rates nicely agree with those from previous spectroscopic work. This new method will be capital for current and future large photometric surveys such as DES, SHARDS, J-PAS, or LSST.

  1. Accurate photometric redshift probability density estimation - method comparison and application

    NASA Astrophysics Data System (ADS)

    Rau, Markus Michael; Seitz, Stella; Brimioulle, Fabrice; Frank, Eibe; Friedrich, Oliver; Gruen, Daniel; Hoyle, Ben

    2015-10-01

    We introduce an ordinal classification algorithm for photometric redshift estimation, which significantly improves the reconstruction of photometric redshift probability density functions (PDFs) for individual galaxies and galaxy samples. As a use case we apply our method to CFHTLS galaxies. The ordinal classification algorithm treats distinct redshift bins as ordered values, which improves the quality of photometric redshift PDFs, compared with non-ordinal classification architectures. We also propose a new single value point estimate of the galaxy redshift, which can be used to estimate the full redshift PDF of a galaxy sample. This method is competitive in terms of accuracy with contemporary algorithms, which stack the full redshift PDFs of all galaxies in the sample, but requires orders of magnitude less storage space. The methods described in this paper greatly improve the log-likelihood of individual object redshift PDFs, when compared with a popular neural network code (ANNZ). In our use case, this improvement reaches 50 per cent for high-redshift objects (z ≥ 0.75). We show that using these more accurate photometric redshift PDFs will lead to a reduction in the systematic biases by up to a factor of 4, when compared with less accurate PDFs obtained from commonly used methods. The cosmological analyses we examine and find improvement upon are the following: gravitational lensing cluster mass estimates, modelling of angular correlation functions and modelling of cosmic shear correlation functions.

  2. Spectroscopic and photometric monitoring of southern post-AGB stars

    NASA Astrophysics Data System (ADS)

    Pooley, D. J.; Cottrell, P. L.; Pollard, K. R.; Albrow, M. D.

    2004-05-01

    We present the results of contemporaneous photometric and spectroscopic monitoring of 20 post-AGB stars from Mt John University Observatory. Photometric measures were carried our suing Johnson BV and Cousins RI filters, and the radial velocity measurements were acquired using spectra from an echelle spectrograph. Our program spanned five years and the stars covered a range of spectral types from B to K in order to investigate the behavior of post-AGB stars as they evolve away from the AGB. A number of stars proved to be variable inways incompatible with post-AGB models and are reclassified. Periodicities are presented for a number of stars. Photometrically, HD 70379 was found to be pulsating in two modes with periods of 85 and 97 d. The radial velocities also varied, with the peak amplitude occurring when the photometry was also changing most. AI CMi presented three different types of spectra associated with photometric brightness, with varying strengths of narrow emission lines and molecular bandheads. The Hα profiles in almost all of the stars show evidence of emission which varies on time scales of days to months. The Na D line profiles are generally complex showing between 4 and 7 components due to both circumstellar and interstellar material.

  3. Photometric NO/sub x/ analyzer helps surpass EPA standards

    SciTech Connect

    Johnson, L.H.

    1983-10-01

    A photometric analyzer helped Monsanto Company of Pensacola, Florida reduce stack emissions to a point where an observer could not tell the difference between a shutdown and normal plant operation. Oxides of nitrogen output levels have been kept within 200 ppm at typical production rates, well within EPA limits.

  4. Adventures in the World of Pulsating Variable Stars: Multisite Photometric Campaigns

    NASA Astrophysics Data System (ADS)

    Szabó, R.

    2004-06-01

    Advantages of photometric multisite campaigns are discussed, then published or prospective results of four - preceding and ongoing - observing runs are presented. Prospects and limits of photometric observations carried out from Hungary with small (~ 1m) telescopes are also outlined.

  5. Photometric identification of objects from Galaxy Evolution Explorer Survey and Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Preethi, K.; Gudennavar, S. B.; Bubbly, S. G.; Murthy, Jayant; Brosch, Noah

    2014-01-01

    We have used Galaxy Evolution Explorer (GALEX) and Sloan Digital Sky Survey (SDSS) observations to extract seven band photometric magnitudes for over 80 000 objects in the vicinity of the North Galactic Pole. Although these had been identified as stars by the SDSS pipeline, we found through fitting with model spectral energy distributions that most were, in fact, of extragalactic origin. Only about 9 per cent of these objects turned out to be main-sequence stars and about 11 per cent were white dwarfs and red giants collectively, while galaxies and quasars contributed to the remaining 80 per cent of the data. We have classified these objects into different spectral types (for the stars) and into different galactic types (for the galaxies). As part of our fitting procedure, we derive the distance and extinction to each object and the photometric redshift towards galaxies and quasars. This method easily allows for the addition of any number of observations to cover a more diverse range of wavelengths, as well as the addition of any number of model templates. The primary objective of this work is to eventually derive a three-dimensional extinction map of the Milky Way Galaxy.

  6. Characterization of a photometric anomaly in lunar Mare Nubium

    NASA Astrophysics Data System (ADS)

    Korokhin, Viktor; Shkuratov, Yuriy; Kaydash, Vadym; Basilevsky, Alexander; Rohachova, Larysa; Velikodsky, Yuri; Opanasenko, Nickolay; Videen, Gorden; Stankevich, Dmitry; Kaluhina, Olena

    2016-03-01

    A novel approach of constructing photometrically seamless mosaics of reflectance, color-ratios, and phase-curve slopes using LROC WAC images has been developed, which can be used to map the photometric parameters of the lunar surface. The approach takes into account both geometric corrections with data on local topography and photometric conjunctions using our simple photometric model. New mosaics obtained with the technique allow more reliable studies of structural and chemical characteristics of the lunar surface. This approach has been applied to analyze the photometric anomaly (21.6 S, 17.7 W, ~40 km in size) in Mare Nubium detected earlier with our Earth-based observations. For each point of the scene the parameters were calculated using the least-square method for several tens of source WAC images. Clementine mosaics also were used in the analysis, e.g., in order to estimate the parameter of maturity degree Is/FeO. The anomaly has low FeO and TiO2 abundance and reveals a higher slope of the phase function than surroundings. Thermal data from LRO Diviner measurements do not show anomalies in this region. We consider this area as a shallow flooding of an elevated formation of highland composition, the material of which could have been excavated and mixed up with upper layers of the lunar surface through meteoroid impacts. The anomalous behavior of the phase function can be explained by the difference of surface structure in the anomaly and surrounding regions on the scale of less than several centimeters. This may be due to larger quantities of small fragments of rocks and clumps on the surface and/or the presence of agglomerates having open structure.

  7. Exploring the SDSS photometric galaxies with clustering redshifts

    NASA Astrophysics Data System (ADS)

    Rahman, Mubdi; Mendez, Alexander J.; Ménard, Brice; Scranton, Ryan; Schmidt, Samuel J.; Morrison, Christopher B.; Budavári, Tamás

    2016-07-01

    We apply clustering-based redshift inference to all extended sources from the Sloan Digital Sky Survey photometric catalogue, down to magnitude r = 22. We map the relationships between colours and redshift, without assumption of the sources' spectral energy distributions (SEDs). We identify and locate star-forming quiescent galaxies, and active galactic nuclei, as well as colour changes due to spectral features, such as the 4000 Å break, redshifting through specific filters. Our mapping is globally in good agreement with colour-redshift tracks computed with SED templates, but reveals informative differences, such as the need for a lower fraction of M-type stars in certain templates. We compare our clustering-redshift estimates to photometric redshifts and find these two independent estimators to be in good agreement at each limiting magnitude considered. Finally, we present the global clustering-redshift distribution of all Sloan extended sources, showing objects up to z ˜ 0.8. While the overall shape agrees with that inferred from photometric redshifts, the clustering-redshift technique results in a smoother distribution, with no indication of structure in redshift space suggested by the photometric-redshift estimates (likely artefacts imprinted by their spectroscopic training set). We also infer a higher fraction of high-redshift objects. The mapping between the four observed colours and redshift can be used to estimate the redshift probability distribution function of individual galaxies. This work is an initial step towards producing a general mapping between redshift and all available observables in the photometric space, including brightness, size, concentration, and ellipticity.

  8. Precision Cosmology with a New Probabilistic Photometric Redshifts Approach

    NASA Astrophysics Data System (ADS)

    Carrasco Kind, Matias; Brunner, R. J.

    2013-06-01

    A complete understanding of both dark energy and dark matter remains one of most important challenges in astrophysics today. Recent theoretical and numerical computations have made important progress in quantifying the role of these dark components on the formation and evolution of galaxies through cosmic time, but observational verification of these predictions and the development of new, more stringent constraints has not kept pace. It is in this context that, photometric redshifts have become more important with the growth of large imaging surveys, such as DES and LSST, that have been designed to address this issue. But their basic implementation has not changed significantly from their original development, as most techniques provide a single photometric redshift estimate and an associated error for the an extragalactic source. In this work, we present a unique and powerful solution that leverages the full information contained in the photometric data to address this cosmological challenge with a new approach that provides accurate photometric redshift probability density functions (PDF) for galaxies. This new approach, which scales efficiently to massive data, efficiently combines standard template fitting techniques with powerful machine learning methods. Included in this framework is our recently developed technique entitled Trees for PhotoZ (TPZ); a new, robust, parallel photometric redshift code that uses prediction trees and random forests to generate photo-z PDFs in a reliable and fast manner. In addition, our approach also provides ancillary information about the internal structure of the data, including the relative importance of variables used during the redshift estimation, an identification of areas in the training sample that provide poor predictions, and an accurate outlier rejection method. We will also present current results of this approach on a variety of datasets and discuss, by using specific examples, how the full photo-z PDF can be

  9. Pan-STARRS1 variability of XMM-COSMOS AGN. I. Impact on photometric redshifts

    NASA Astrophysics Data System (ADS)

    Simm, T.; Saglia, R.; Salvato, M.; Bender, R.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Metcalfe, N.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2015-12-01

    Aims: Upcoming large area sky surveys like Euclid and eROSITA, which are dedicated to studying the role of dark energy in the expansion history of the Universe and the three-dimensional mass distribution of matter, crucially depend on accurate photometric redshifts. The identification of variable sources, such as active galactic nuclei (AGNs), and the achievable redshift accuracy for varying objects are important in view of the science goals of the Euclid and eROSITA missions. Methods: We probe AGN optical variability for a large sample of X-ray-selected AGNs in the XMM-COSMOS field, using the multi-epoch light curves provided by the Pan-STARRS1 (PS1) 3π and Medium Deep Field surveys. To quantify variability we employed a simple statistic to estimate the probability of variability and the normalized excess variance to measure the variability amplitude. Utilizing these two variability parameters, we defined a sample of varying AGNs for every PS1 band. We investigated the influence of variability on the calculation of photometric redshifts by applying three different input photometry sets for our fitting procedure. For each of the five PS1 bands gP1, rP1, iP1, zP1, and yP1, we chose either the epochs minimizing the interval in observing time, the median magnitude values, or randomly drawn light curve points to compute the redshift. In addition, we derived photometric redshifts using PS1 photometry extended by GALEX/IRAC bands. Results: We find that the photometry produced by the 3π survey is sufficient to reliably detect variable sources provided that the fractional variability amplitude is at least ~3%. Considering the photometric redshifts of variable AGNs, we observe that minimizing the time spacing of the chosen points yields superior photometric redshifts in terms of the percentage of outliers (33%) and accuracy (0.07), outperforming the other two approaches. Drawing random points from the light curve gives rise to typically 57% of outliers and an accuracy of

  10. Charge characteristics of humic and fulvic acids: comparative analysis by colloid titration and potentiometric titration with continuous pK-distribution function model.

    PubMed

    Bratskaya, S; Golikov, A; Lutsenko, T; Nesterova, O; Dudarchik, V

    2008-09-01

    Charge characteristics of humic and fulvic acids of a different origin (inshore soils, peat, marine sediments, and soil (lysimetric) waters) were evaluated by means of two alternative methods - colloid titration and potentiometric titration. In order to elucidate possible limitations of the colloid titration as an express method of analysis of low content of humic substances we monitored changes in acid-base properties and charge densities of humic substances with soil depth, fractionation, and origin. We have shown that both factors - strength of acidic groups and molecular weight distribution in humic and fulvic acids - can affect the reliability of colloid titration. Due to deviations from 1:1 stoichiometry in interactions of humic substances with polymeric cationic titrant, the colloid titration can underestimate total acidity (charge density) of humic substances with domination of weak acidic functional groups (pK>6) and high content of the fractions with molecular weight below 1kDa.

  11. Radial velocity variations of photometrically quiet, chromospherically inactive Kepler stars: A link between RV jitter and photometric flicker

    SciTech Connect

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua; Wright, Jason T.; Aigrain, Suzanne; Basri, Gibor; Johnson, John A.; Howard, Andrew W.; Walkowicz, Lucianne M.

    2014-02-01

    We compare stellar photometric variability, as measured from Kepler light curves by Basri et al., with measurements of radial velocity (RV) rms variations of all California Planet Search overlap stars. We newly derive rotation periods from the Kepler light curves for all of the stars in our study sample. The RV variations reported herein range from less than 4 to 135 m s{sup –1}, yet the stars all have amplitudes of photometric variability less than 3 mmag, reflecting the preference of the RV program for chromospherically 'quiet' stars. Despite the small size of our sample, we find with high statistical significance that the RV rms manifests strongly in the Fourier power spectrum of the light curve: stars that are noisier in RV have a greater number of frequency components in the light curve. We also find that spot models of the observed light curves systematically underpredict the observed RV variations by factors of ∼2-1000, likely because the low-level photometric variations in our sample are driven by processes not included in simple spot models. The stars best fit by these models tend to have simpler light curves, dominated by a single relatively high-amplitude component of variability. Finally, we demonstrate that the RV rms behavior of our sample can be explained in the context of the photometric variability evolutionary diagram introduced by Bastien et al. We use this diagram to derive the surface gravities of the stars in our sample, revealing many of them to have moved off the main sequence. More generally, we find that the stars with the largest RV rms are those that have evolved onto the 'flicker floor' sequence in that diagram, characterized by relatively low amplitude but highly complex photometric variations which grow as the stars evolve to become subgiants.

  12. Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations

    NASA Astrophysics Data System (ADS)

    Ebling, A. M.; Schijf, J.

    2008-12-01

    In pursuit of our ultimate goal to better understand the prodigious capacity of the marine macroalga Ulva lactuca (sea lettuce) for adsorbing a broad range of dissolved trace metals from seawater, we performed an initial characterization of its surface functional groups. Specifically, the number of distinct functional groups as well as their individual bulk concentrations and acid dissociation constants (pKas) were determined by potentiometric titrations in NaCl solutions of various ionic strengths (I = 0.01-5.0 M), under inert nitrogen atmosphere at 25°C. Depending on the ionic strength, Ulva samples were manually titrated down to pH 2 or 3 with 1 N HCl and then up to pH 10 with 1 N NaOH in steps of 0.1-0.2 units, continuously monitoring pH with a glass combination electrode. Titrations of a dehydrated Ulva standard reference material (BCR-279) were compared with fresh Ulva tissue cultured in our laboratory. A titration in filtered natural seawater was also compared with one in an NaCl solution of equal ionic strength. Equilibrium constants for the ionization of water in NaCl solutions as a function of ionic strength were obtained from the literature. Fits to the titration data ([H]T vs. pH) were performed with the FITEQL4.0 computer code using non-electrostatic 3-, 4-, and 5-site models, either by fixing ionic strength at its experimental value or by allowing it to be extrapolated to zero, while considering all functional group pKas and bulk concentrations as adjustable parameters. Since pKas and bulk concentrations were found to be strongly correlated, the latter were also fixed in some cases to further constrain the pKas. Whereas these calculations are currently ongoing, preliminary results point to three, possibly four, functional groups with pKas of about 4.1, 6.3, and 9.5 at I = 0. Bulk concentrations of the three groups are very similar, about 5-6×10-4 mol/g based on dry weight, which suggests that all are homogeneously distributed over the surface and

  13. A titration model for evaluating calcium hydroxide removal techniques

    PubMed Central

    PHILLIPS, Mark; McCLANAHAN, Scott; BOWLES, Walter

    2015-01-01

    Objective Calcium hydroxide (Ca(OH)2) has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH)2 left after different endodontic irrigation methods. Material and Methods Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH)2 for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH)2 recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH)2 followed by gross Ca(OH)2 removal using hand files and randomized treatment of either: 1) Syringe irrigation; 2) Syringe irrigation with use of an apical file; 3) Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI), or 4) Syringe irrigation with apical file and PUI (n=12/group). Residual Ca(OH)2 was dissolved with glycerin and titrated to measure residual Ca(OH)2 left in the root. Results No method completely removed all residual Ca(OH)2. The addition of 30 s PUI with or without apical file use removed Ca(OH)2 significantly better than irrigation alone. Conclusions This technique allowed quantification of residual Ca(OH)2. The use of PUI (with or without apical file) resulted in significantly lower Ca(OH)2 residue compared to irrigation alone. PMID:25760272

  14. Titratable acidity of beverages influences salivary pH recovery.

    PubMed

    Tenuta, Livia Maria Andaló; Fernández, Constanza Estefany; Brandão, Ana Carolina Siqueira; Cury, Jaime Aparecido

    2015-01-01

    A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control) were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively) and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and < 0.005 mmols OH- to reach pH 5.5, respectively). Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

  15. A novel approach for high precision rapid potentiometric titrations: application to hydrazine assay.

    PubMed

    Sahoo, P; Malathi, N; Ananthanarayanan, R; Praveen, K; Murali, N

    2011-11-01

    We propose a high precision rapid personal computer (PC) based potentiometric titration technique using a specially designed mini-cell to carry out redox titrations for assay of chemicals in quality control laboratories attached to industrial, R&D, and nuclear establishments. Using this technique a few microlitre of sample (50-100 μl) in a total volume of ~2 ml solution can be titrated and the waste generated after titration is extremely low comparing to that obtained from the conventional titration technique. The entire titration including online data acquisition followed by immediate offline analysis of data to get information about concentration of unknown sample is completed within a couple of minutes (about 2 min). This facility has been created using a new class of sensors, viz., pulsating sensors developed in-house. The basic concept in designing such instrument and the salient features of the titration device are presented in this paper. The performance of the titration facility was examined by conducting some of the high resolution redox titrations using dilute solutions--hydrazine against KIO(3) in HCl medium, Fe(II) against Ce(IV) and uranium using Davies-Gray method. The precision of titrations using this innovative approach lies between 0.048% and 1.0% relative standard deviation in different redox titrations. With the evolution of this rapid PC based titrator it was possible to develop a simple but high precision potentiometric titration technique for quick determination of hydrazine in nuclear fuel dissolver solution in the context of reprocessing of spent nuclear fuel in fast breeder reactors.

  16. Acid Base Titrations in Nonaqueous Solvents and Solvent Mixtures

    NASA Astrophysics Data System (ADS)

    Barcza, Lajos; Buvári-Barcza, Ágnes

    2003-07-01

    The acid base determination of different substances by nonaqueous titrations is highly preferred in pharmaceutical analyses since the method is quantitative, exact, and reproducible. The modern interpretation of the reactions in nonaqueous solvents started in the last century, but several inconsistencies and unsolved problems can be found in the literature. The acid base theories of Brønsted Lowry and Lewis as well as the so-called solvent theory are outlined first, then the promoting (and leveling) and the differentiating effects are discussed on the basis of the hydrogen-bond concept. Emphasis is put on the properties of formic acid and acetic anhydride since their importance is increasing.

  17. Complex formation of fenchone with α-cyclodextrin: NMR titrations.

    PubMed

    Nowakowski, Michał; Ejchart, Andrzej

    2014-01-01

    (13)C NMR titration studies of inclusion complexes of bicyclic terpenoid, fenchone enantiomers with α-cyclodextrin revealed their 1:2 guest-host stoichiometry. Sequential binding constants were determined indicating a strong binding cooperativity of two α-cyclodextrin to fenchone. The overall association constants were used to calculate the Gibbs free energies of diastereomeric complex formation, which might be used as a measure of chiral recognition of fenchone by α-cyclodextrin. These results were compared with corresponding data derived for camphor, which is an isomeric bicyclic terpenoid.

  18. Studying the allosteric energy cycle by isothermal titration calorimetry.

    PubMed

    Martinez-Julvez, Marta; Abian, Olga; Vega, Sonia; Medina, Milagros; Velazquez-Campoy, Adrian

    2012-01-01

    Isothermal titration calorimetry (ITC) is a powerful biophysical technique which allows a complete thermodynamic characterization of protein interactions with other molecules. The possibility of dissecting the Gibbs energy of interaction into its enthalpic and entropic contributions, as well as the detailed additional information experimentally accessible on the intermolecular interactions (stoichiometry, cooperativity, heat capacity changes, and coupled equilibria), make ITC a suitable technique for studying allosteric interactions in proteins. Two experimental methodologies for the characterization of allosteric heterotropic ligand interactions by ITC are described in this chapter, illustrated with two proteins with markedly different structural and functional features: a photosynthetic electron transfer protein and a drug target viral protease.

  19. Interaction between bisphenol A and tannic Acid: Spectroscopic titration approach

    NASA Astrophysics Data System (ADS)

    Omoike, Anselm; Brandt, Benjamin

    2011-06-01

    The interaction between tannic acid (TA) and bisphenol A (BPA), an endocrine disruptor, was studied by absorption and fluorescence titration techniques. The binding constants and corresponding thermodynamic parameters at different temperatures (294, 296, 298, 300 and 303 K) were determined. The intrinsic fluorescence of BPA was strongly quenched by TA and the quenching mechanism is attributed to static quenching. The thermodynamic data revealed that the formation of TA-BPA complex was exothermic, entropic-driven, and spontaneous. Furthermore, hydrogen and van der Waals interactions seem to be the major driving forces for the formation of the nonfluorescent TA-BPA complex.

  20. Semi-automated potentiometric titration method for uranium characterization.

    PubMed

    Cristiano, B F G; Delgado, J U; da Silva, J W S; de Barros, P D; de Araújo, R M S; Lopes, R T

    2012-07-01

    The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. PMID:22154105

  1. Isothermal Titration Calorimetry: Assisted Crystallization of RNA-Ligand Complexes.

    PubMed

    Da Veiga, Cyrielle; Mezher, Joelle; Dumas, Philippe; Ennifar, Eric

    2016-01-01

    The success rate of nucleic acids/ligands co-crystallization can be significantly improved by performing preliminary biophysical analyses. Among suitable biophysical approaches, isothermal titration calorimetry (ITC) is certainly a method of choice. ITC can be used in a wide range of experimental conditions to monitor in real time the formation of the RNA- or DNA-ligand complex, with the advantage of providing in addition the complete binding profile of the interaction. Following the ITC experiment, the complex is ready to be concentrated for crystallization trials. This chapter describes a detailed experimental protocol for using ITC as a tool for monitoring RNA/small molecule binding, followed by co-crystallization.

  2. Interaction between bisphenol A and tannic acid: spectroscopic titration approach.

    PubMed

    Omoike, Anselm; Brandt, Benjamin

    2011-06-01

    The interaction between tannic acid (TA) and bisphenol A (BPA), an endocrine disruptor, was studied by absorption and fluorescence titration techniques. The binding constants and corresponding thermodynamic parameters at different temperatures (294, 296, 298, 300 and 303 K) were determined. The intrinsic fluorescence of BPA was strongly quenched by TA and the quenching mechanism is attributed to static quenching. The thermodynamic data revealed that the formation of TA-BPA complex was exothermic, entropic-driven, and spontaneous. Furthermore, hydrogen and van der Waals interactions seem to be the major driving forces for the formation of the nonfluorescent TA-BPA complex.

  3. THE PHOTOMETRIC CLASSIFICATION SERVER FOR Pan-STARRS1

    SciTech Connect

    Saglia, R. P.; Bender, R.; Seitz, S.; Senger, R.; Snigula, J.; Phleps, S.; Wilman, D.; Tonry, J. L.; Burgett, W. S.; Chambers, K. C.; Heasley, J. N.; Kaiser, N.; Magnier, E. A.; Morgan, J. S.; Greisel, N.; Bailer-Jones, C. A. L.; Klement, R. J.; Rix, H.-W.; Smith, K.; Green, P. J.; and others

    2012-02-20

    The Pan-STARRS1 survey is obtaining multi-epoch imaging in five bands (g{sub P1} r{sub P1} i{sub P1} z{sub P1} y{sub P1}) over the entire sky north of declination -30 deg. We describe here the implementation of the Photometric Classification Server (PCS) for Pan-STARRS1. PCS will allow the automatic classification of objects into star/galaxy/quasar classes based on colors and the measurement of photometric redshifts for extragalactic objects, and will constrain stellar parameters for stellar objects, working at the catalog level. We present tests of the system based on high signal-to-noise photometry derived from the Medium-Deep Fields of Pan-STARRS1, using available spectroscopic surveys as training and/or verification sets. We show that the Pan-STARRS1 photometry delivers classifications and photometric redshifts as good as the Sloan Digital Sky Survey (SDSS) photometry to the same magnitude limits. In particular, our preliminary results, based on this relatively limited data set down to the SDSS spectroscopic limits, and therefore potentially improvable, show that stars are correctly classified as such in 85% of cases, galaxies in 97%, and QSOs in 84%. False positives are less than 1% for galaxies, Almost-Equal-To 19% for stars, and Almost-Equal-To 28% for QSOs. Moreover, photometric redshifts for 1000 luminous red galaxies up to redshift 0.5 are determined to 2.4% precision (defined as 1.48 Multiplication-Sign Median|z{sub phot} - z{sub spec}|/(1 + z)) with just 0.4% catastrophic outliers and small (-0.5%) residual bias. For bluer galaxies up to the same redshift, the residual bias (on average -0.5%) trend, percentage of catastrophic failures (1.2%), and precision (4.2%) are higher, but still interestingly small for many science applications. Good photometric redshifts (to 5%) can be obtained for at most 60% of the QSOs of the sample. PCS will create a value-added catalog with classifications and photometric redshifts for eventually many millions of sources.

  4. [Titration of the antibodies to the Crimean hemorrhagic fever virus in a drop of the cell suspension from infected tissue cultures by means of indirect immunofluorescence].

    PubMed

    Zgurskaia, G N; Chumakov, M P

    1977-01-01

    A comparatively simple method has been developed and tested for the detection and titration of antibody to Crimean hemorrhagic fever virus (CHF) by indirect immunofluorescence on slides with previously prepared acetone-inactivated virus in drops of cell suspension from infected BHK-21 and 6619 cell cultures. The antibody titers determined by the indirect immunofluorescence procedures were 4- and 8-fold higher than those determined by the complement-fixation test. This opens the possibility of using non-infectious antigens of cell suspensions for detection or titration by the FA procedure of antibody to CHF virus which may be of importance to diagnostic laboratories which have no conditions for work with live virus.

  5. Systemic errors in quantitative polymerase chain reaction titration of self-complementary adeno-associated viral vectors and improved alternative methods.

    PubMed

    Fagone, Paolo; Wright, J Fraser; Nathwani, Amit C; Nienhuis, Arthur W; Davidoff, Andrew M; Gray, John T

    2012-02-01

    Self-complementary AAV (scAAV) vector genomes contain a covalently closed hairpin derived from a mutated inverted terminal repeat that connects the two monomer single-stranded genomes into a head-to-head or tail-to-tail dimer. We found that during quantitative PCR (qPCR) this structure inhibits the amplification of proximal amplicons and causes the systemic underreporting of copy number by as much as 10-fold. We show that cleavage of scAAV vector genomes with restriction endonuclease to liberate amplicons from the covalently closed terminal hairpin restores quantitative amplification, and we implement this procedure in a simple, modified qPCR titration method for scAAV vectors. In addition, we developed and present an AAV genome titration procedure based on gel electrophoresis that requires minimal sample processing and has low interassay variability, and as such is well suited for the rigorous quality control demands of clinical vector production facilities.

  6. Derivation of sky quality indicators from photometrically calibrated all-sky image mosaics

    NASA Astrophysics Data System (ADS)

    Duriscoe, Dan M.; Moore, Chadwick A.; Luginbuhl, Christian B.

    2015-08-01

    A large database of high resolution all-sky measurements of V-band night sky brightness at sites in U.S. National Parks and astronomical observatories is utilized to describe sky quality over a wide geographic area. Mosaics of photometrically calibrated V-band imagery are processed with a semi-automated procedure to reveal the effects of artificial sky glow through graphical presentation and numeric indicators of artificial sky brightness. Comparison with simpler methods such as the use of the Unihedron SQM and naked eye limiting magnitude reveal that areas near the horizon, which are not typically captured with single-channel measurements, contribute significantly to the indicators maximum vertical illuminance, maximum sky luminance, and average all-sky luminance. Distant sources of sky glow may represent future threats to areas of the sky nearer the zenith. Timely identification and quantification of these threats may allow mitigating strategies to be implemented.

  7. A photometric method for the estimation of the oil yield of oil shale

    USGS Publications Warehouse

    Cuttitta, Frank

    1951-01-01

    A method is presented for the distillation and photometric estimation of the oil yield of oil-bearing shales. The oil shale is distilled in a closed test tube and the oil extracted with toluene. The optical density of the toluene extract is used in the estimation of oil content and is converted to percentage of oil by reference to a standard curve. This curve is obtained by relating the oil yields determined by the Fischer assay method to the optical density of the toluene extract of the oil evolved by the new procedure. The new method gives results similar to those obtained by the Fischer assay method in a much shorter time. The applicability of the new method to oil-bearing shale and phosphatic shale has been tested.

  8. Photometric flats: an essential ingredient for photometry with wide-field imagers

    NASA Astrophysics Data System (ADS)

    Selman, Fernando J.

    2004-09-01

    We discuss the challenges to photometry introduced by internal redistribution of light in wide-field imaging cameras with focal-reducers. We have developed a simple least-squares procedure which can be used to determine the zero-point variations across the field. The method uses three orthogonally offseted images of a reasonably dense stellar field, plus an image containing at least three standard stars scattered across the field. The method, which does not require rotating the instrument, have been applied to correct data from the Wide Field Imager at La Silla. It has been shown to reduce a 12% center-to-edge gradient down to a ~2% rms variation accross the field. A new method which can be used with data taken during non-photometric nights is also presented.

  9. Gas chromatography with flame photometric detection of 31 organophosphorus pesticide residues in Alpinia oxyphylla dried fruits.

    PubMed

    Zhao, Xiangsheng; Kong, Weijun; Wei, Jianhe; Yang, Meihua

    2014-11-01

    A simple, rapid and effective gas chromatography-flame photometric detection method was established for simultaneous multi-component determination of 31 organophosphorus pesticides (OPPs) residues in Alpinia oxyphylla, which is widely consumed as a traditional medicine and food in China. Sample preparation was completed in a single step without any clean-up procedure. All pesticides expressed good linear relationships between 0.004 and 1.0 μg/mL with correlation coefficients higher than 0.9973. The method gave satisfactory recoveries for most pesticides. The limits of detection varied from 1 to 10 ng/mL, and the limits of quantification (LOQs) were between 4 and 30 ng/mL. The proposed method was successfully applied to 55 commercial samples purchased from five different areas. Five pesticide residues were detected in four (7.27%) samples. The positive samples were confirmed by gas chromatography with tandem mass spectrometry (GC-MS/MS).

  10. A Photometric Classification of the SAGE LMC Point Source Catalog

    NASA Astrophysics Data System (ADS)

    Marengo, Massimo; Antoniou, V.; SAGE Collaboration

    2014-01-01

    The Spitzer SAGE Large Magellanic Cloud (LMC) photometric catalog lists over 7.2 million sources detected with the Spitzer space telescope. This catalog has been cross-correlated with the near-IR 2MASS and IRSF surveys, as well as with optical photometry from the MCPS database. This combined catalog is an invaluable tool for the study of LMC stellar populations, and to understand the life cycle of gas and dust in the LMC. To fully leverage the broad wavelength coverage of this database, we have developed a novel technique for the photometric classification of the SAGE LMC point source catalog, based on a weighted k-Nearest Neighbor method. This technique allows the classification of most LMC sources based on templates that have been identified spectroscopically, without a-priori assumptions about their spectral characteristics. We present here the details of our classification method, and the main results of our work.

  11. Photometric study of the pulsating, eclipsing binary OO DRA

    SciTech Connect

    Zhang, X. B.; Deng, L. C.; Tian, J. F.; Wang, K.; Yan, Z. Z.; Luo, C. Q.; Sun, J. J.; Liu, Q. L.; Xin, H. Q.; Zhou, Q.; Luo, Z. Q.

    2014-12-01

    We present a comprehensive photometric study of the pulsating, eclipsing binary OO Dra. Simultaneous B- and V-band photometry of the star was carried out on 14 nights. A revised orbital period and a new ephemeris were derived from the data. The first photometric solution of the binary system and the physical parameters of the component stars are determined. They reveal that OO Dra could be a detached system with a less-massive secondary component nearly filling its Roche lobe. By subtracting the eclipsing light changes from the data, we obtained the intrinsic pulsating light curves of the hotter, massive primary component. A frequency analysis of the residual light yields two confident pulsation modes in both B- and V-band data with the dominant frequency detected at 41.865 c/d. A brief discussion concerning the evolutionary status and the pulsation nature of the binary system is finally given.

  12. Galaxy clustering with photometric surveys using PDF redshift information

    NASA Astrophysics Data System (ADS)

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-06-01

    Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colours, that are obtained through multiband imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths are Δz = 0.1, the use of the entire PDF reduces the typical measurement bias from 5 per cent, when using single point estimates, to 3 per cent.

  13. The photometric period of the recurrent Nova T Pyxidis

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Landolt, Arlo U.; Vogt, Nikolaus; Buckley, David; Warner, Brian; Walker, Alistair R.; Bond, Howard E.

    1992-01-01

    The paper presents 1713 photometric measurements of T Pyx from 1966 to 1990. The light curve of T Pyx shows roughly sinusoidal variations with a typical amplitude of 0.09 mag and a time scale of 2 hr. Discrete Fourier transforms of data from individual nights and runs reveal a highly significant periodic modulation. This modulation is proven to be coherent only on time scales shorter than from 6 d to under 1 d. The present period for the modulation is 0.07616 +/- 0.00017 d. Since other stars have variable photometric periods (possibly related to the superhump phenomenon) which are slightly different from the orbital period, an orbital period of about 0.073 d for T Pyx is suggested.

  14. Photometric Reverberation Mapping with a Small Aperture Telescope

    NASA Astrophysics Data System (ADS)

    Hood, Carol E.; Rivera, Noah I.; Thackeray-Lacko, Beverly; Powers, Randy M.; Stuckey, Harrison; Watson, Rene; Hood, Michael A.

    2015-01-01

    We present photometric observations of a sample of bright, broad-line AGN in order to monitor variability and verify their black hole masses using the photometric reverberation mapping technique. Observations were taken, primarily remotely, using the 20-inch telescope at the Murillo Family Observatory, a campus-based observatory located on the outskirts of the Southern California metro area, in both monitored and automated mode nightly in BVRI over a period of 2-5 months. We will show the viability of such a technique for small-aperture telescopes in bright-sky locations and discuss the possibilities of extending this program in the future. We also note that undergraduate students (both from 4-year and community colleges) have been and will continue to be instrumental in the success of similar research programs at CSUSB.

  15. Galaxy clustering with photometric surveys using PDF redshift information

    DOE PAGES

    Asorey, J.; Carrasco Kind, M.; Sevilla-Noarbe, I.; Brunner, R. J.; Thaler, J.

    2016-03-28

    Here, photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or colors, that are obtained through multi-band imaging to produce a probability density function (PDF) for each galaxy in the map. We used simulated data to study the effect of using different photo-z estimators to assign galaxies to redshift bins in order to compare their effects on angular clustering and galaxy bias measurements. We found that if we use the entire PDF, rather than a single-point (mean or mode) estimate, the deviations are less biased, especially when using narrow redshift bins. When the redshift bin widths aremore » $$\\Delta z=0.1$$, the use of the entire PDF reduces the typical measurement bias from 5%, when using single point estimates, to 3%.« less

  16. DNF - Galaxy photometric redshift by Directional Neighbourhood Fitting

    NASA Astrophysics Data System (ADS)

    De Vicente, J.; Sánchez, E.; Sevilla-Noarbe, I.

    2016-07-01

    Wide field images taken in several photometric bands allow simultaneous measurement of redshifts for thousands of galaxies. A variety of algorithms to make this measurement have appeared in the last few years, the majority of which can be classified as either template- or training-based methods. Among the latter, nearest neighbour estimators stand out as one of the most successful, in terms of both precision and the quality of error estimation. In this paper we describe the Directional Neighbourhood Fitting (DNF) algorithm based on the following: a new neighbourhood metric (Directional Neighbourhood), a photo-z estimation strategy (Neighbourhood Fitting) and a method for generating the photo-z probability distribution function. We compare DNF with other well-known empirical photometric redshift tools using different public data sets (Sloan Digital Sky Survey, VIMOS VLT Deep Survey and Photo-z Accuracy Testing). DNF achieves high-quality results with reliable error.

  17. Measuring photometric redshifts using galaxy images and Deep Neural Networks

    NASA Astrophysics Data System (ADS)

    Hoyle, B.

    2016-07-01

    We propose a new method to estimate the photometric redshift of galaxies by using the full galaxy image in each measured band. This method draws from the latest techniques and advances in machine learning, in particular Deep Neural Networks. We pass the entire multi-band galaxy image into the machine learning architecture to obtain a redshift estimate that is competitive, in terms of the measured point prediction metrics, with the best existing standard machine learning techniques. The standard techniques estimate redshifts using post-processed features, such as magnitudes and colours, which are extracted from the galaxy images and are deemed to be salient by the user. This new method removes the user from the photometric redshift estimation pipeline. However we do note that Deep Neural Networks require many orders of magnitude more computing resources than standard machine learning architectures, and as such are only tractable for making predictions on datasets of size ≤50k before implementing parallelisation techniques.

  18. Photometric study of the eclipsing binary RR Leporis

    NASA Astrophysics Data System (ADS)

    Vyas, M. L.; Abhyankar, K. D.

    1989-11-01

    The eclipsing binary RR Leporis has been observed on 42 nights during 1982-1987 in standard U, B and V passbands. The complete light curves and photometric solutions for this binary system are presented. The preliminary elements derived by Russell-Merrill method were used as inputs in Wilson-Devinney's Differential Corrections Program. All the three light curves in UBV were treated simultaneously. Two different Mode 5 solutions, in which the secondary fills its roche lobe, fitted the light curves equally well. On comparing these photometric elements with those given by Samec et al. (1988), it was found that the solution is indeterminate because i and q are strongly correlated. In the absence of any accurate spectroscopic data, it is premature to derive absolute dimensions of the system. The most likely parameters are given.

  19. Observational Tests to Detect Photometric Reverberation in H-alpha

    NASA Astrophysics Data System (ADS)

    Joner, Michael D.; Carroll, Carla

    2014-06-01

    We present photometric observations of several AGN that were secured with the 0.9-m telescope located at the West Mountain Observatory that is operated by Brigham Young University. The new observations use standard BVR filters along with several custom filters that are part of a red shifted H-alpha set. Light curves are presented for several of the targets along with a summary of the analysis made to detect lag times between the continuum and broad emission line flux as evidence for photometric reverberation. Plans are presented for future research that will continue along these lines.We thank the Department of Physics and Astronomy along with the College of Physical and Mathematical Sciences at Brigham Young University for continued support of the research work being done at the West Mountain Observatory.

  20. Photometric Variability of a Large Sample of Be Stars

    NASA Astrophysics Data System (ADS)

    Labadie-Bartz, Jonathan; Pepper, Joshua; KELT Collaboration

    2016-01-01

    Be stars are main sequence, rapidly rotating B-type stars with emission lines in their spectra attributed to a gaseous circumstellar disk. Variability across a wide range of timescales (from hours to decades) is observed in this class of objects, including stellar pulsations, outbursts, oscillations in the circumstellar disk, and the total disappearance (or reappearance) of the disk. Using data from the KELT survey (Kilodegree Extremely Little Telescope; a wide-field photometric survey designed to find transiting exoplanets with high precision of ~1% and baselines up to 10 years for ~3 million objects), we investigate the light curves of ~300 known Be stars and find many systems exhibiting the aforementioned types of variability. Many of these Be stars also have existing spectra simultaneous with the KELT photometry, providing a unique look into the correlation between spectroscopic features and photometric variability, and allowing us to study how these observables relate to the underlying physical processes present in Be stars.

  1. KEPLER MISSION DESIGN, REALIZED PHOTOMETRIC PERFORMANCE, AND EARLY SCIENCE

    SciTech Connect

    Koch, David G.; Borucki, William J.; Lissauer, Jack J.; Basri, Gibor; Marcy, Geoffrey; Batalha, Natalie M.; Brown, Timothy M.; Caldwell, Douglas; DeVore, Edna; Jenkins, Jon; Christensen-Dalsgaard, Joergen; Cochran, William D.; Dunham, Edward W.; Gautier, Thomas N.; Gilliland, Ronald L.; Gould, Alan; Kondo, Yoji; Monet, David

    2010-04-20

    The Kepler Mission, launched on 2009 March 6, was designed with the explicit capability to detect Earth-size planets in the habitable zone of solar-like stars using the transit photometry method. Results from just 43 days of data along with ground-based follow-up observations have identified five new transiting planets with measurements of their masses, radii, and orbital periods. Many aspects of stellar astrophysics also benefit from the unique, precise, extended, and nearly continuous data set for a large number and variety of stars. Early results for classical variables and eclipsing stars show great promise. To fully understand the methodology, processes, and eventually the results from the mission, we present the underlying rationale that ultimately led to the flight and ground system designs used to achieve the exquisite photometric performance. As an example of the initial photometric results, we present variability measurements that can be used to distinguish dwarf stars from red giants.

  2. A microfabrication-based approach to quantitative isothermal titration calorimetry.

    PubMed

    Wang, Bin; Jia, Yuan; Lin, Qiao

    2016-04-15

    Isothermal titration calorimetry (ITC) directly measures heat evolved in a chemical reaction to determine equilibrium binding properties of biomolecular systems. Conventional ITC instruments are expensive, use complicated design and construction, and require long analysis times. Microfabricated calorimetric devices are promising, although they have yet to allow accurate, quantitative ITC measurements of biochemical reactions. This paper presents a microfabrication-based approach to integrated, quantitative ITC characterization of biomolecular interactions. The approach integrates microfabricated differential calorimetric sensors with microfluidic titration. Biomolecules and reagents are introduced at each of a series of molar ratios, mixed, and allowed to react. The reaction thermal power is differentially measured, and used to determine the thermodynamic profile of the biomolecular interactions. Implemented in a microdevice featuring thermally isolated, well-defined reaction volumes with minimized fluid evaporation as well as highly sensitive thermoelectric sensing, the approach enables accurate and quantitative ITC measurements of protein-ligand interactions under different isothermal conditions. Using the approach, we demonstrate ITC characterization of the binding of 18-Crown-6 with barium chloride, and the binding of ribonuclease A with cytidine 2'-monophosphate within reaction volumes of approximately 0.7 µL and at concentrations down to 2mM. For each binding system, the ITC measurements were completed with considerably reduced analysis times and material consumption, and yielded a complete thermodynamic profile of the molecular interaction in agreement with published data. This demonstrates the potential usefulness of our approach for biomolecular characterization in biomedical applications. PMID:26655185

  3. Determination of berkelium by the method of spectrophotometric titration

    SciTech Connect

    Frolova, L.M.; Vityutnev, V.M.; Vasil'ev, V.M.

    1987-01-01

    The method that the authors propose consists of the following: berkelium is oxidized electrochemically, spectrophotometric titration of berkelium(IV) by a solution of the reducing agent is performed, and the amount of berkelium(IV) is determined according to the volume of the titrant, and considering the degree of oxidation of berkelium(III) to berkelium(IV), the total berkelium content in the sample is also determined. In this case the necessity for preliminary determination of the molar extinction coefficient of berkelium(IV) under the experimental conditions falls away. Moreover, the radiometric method of determining the berkelium content is not used. Successful titration requires selection of a reagent which, on the one hand, would rapidly reduce berkelium(VI), but on the other hand, neither itself nor the reaction products would interfere with the measurement of the optical density of berkelium(IV). As is well known, berkelium(IV) is quantitatively and rapidly reduced by hydrogen peroxide (10, 11), hydroxylamine (11), and nitrous acid (9). After preliminary experiments, they selected hydrogen peroxide and sodium nitrite as the titrants.

  4. [Alkalimetric titrations of salts of organic bases in the Pharmacopoeia].

    PubMed

    Bezáková, Zelmíra; Stankovičová, Mária

    2013-12-01

    Modified methods - alkalimetry in ethanol 70% with a defined small volume of hydrochloric acid 0.01 mol/l added to the solution of the sample before the titration and alkalimetry in ethanol 70% or ethanol 96% alone with potentiometric end-point detection for the assay of halide salts of 11 organic N-bases has been investigated. The results were compared to those obtained by the method of the European Pharmacopoeia 7th Ed. (Ph. Eur. 7th Ed.). The Ph. Eur. 7th Ed. use for 8 investigated substances alkalimetry in alcohol 96 % with a defined small volume of hydrochloric acid 0.01 mol/l (5 ml) with potentiometric end-point detection: Cinchocaine hydrochloride, Codeine hydrochloride dihydrate, Ethylmorphine hydrochloride, Lidocaine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride, Quinine hydrochloride, Tetracaine hydrochloride. Our results revealed that the Ph. Eur. 7th Ed. method did not work for 5 drugs from this group: Cinchocaine hydrochloride, Ethylmorphine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride and Tetracaine hydrochloride. In the group of investigated substances we included also drugs with the character of weak organic bases for which Ph. Eur. 7th Ed. prescribed different methods for their assay: Thiamine hydrochloride and Pyridoxine hydrochloride - acidimetric titration in non-aqueous solvents with perchloric acid and Procaine hydrochloride - determination of primary aromatic amino-nitrogen (Ph. Eur. 7th Ed., chapter 2.5.8).

  5. Titration of human coronaviruses using an immunoperoxidase assay.

    PubMed

    Lambert, Francine; Jacomy, Helene; Marceau, Gabriel; Talbot, Pierre J

    2008-01-01

    Determination of infectious viral titers is a basic and essential experimental approach for virologists. Classical plaque assays cannot be used for viruses that do not cause significant cytopathic effects, which is the case for prototype strains 229E and OC43 of human coronavirus (HCoV).Therefore, an alternative indirect immunoperoxidase assay (IPA) was developed for the detection and titration of these viruses and is described herein. Susceptible cells are inoculated with serial logarithmic dilutions of virus-containing samples in a 96-well plate format. After viral growth,viral detection by IPA yields the infectious virus titer, expressed as 'Tissue Culture Infectious Dose 50 percent' (TCID50). This represents the dilution of a virus-containing sample at which half of a series of laboratory wells contain infectious replicating virus. This technique provides are liable method for the titration of HCoV-229E and HCoV-OC43 in biological samples such as cells, tissues and fluids [corrected].

  6. Measuring the Kinetics of Molecular Association by Isothermal Titration Calorimetry.

    PubMed

    Vander Meulen, Kirk A; Horowitz, Scott; Trievel, Raymond C; Butcher, Samuel E

    2016-01-01

    The real-time power response inherent in an isothermal titration calorimetry (ITC) experiment provides an opportunity to directly analyze association kinetics, which, together with the conventional measurement of thermodynamic quantities, can provide an incredibly rich description of molecular binding in a single experiment. Here, we detail our application of this method, in which interactions occurring with relaxation times ranging from slightly below the instrument response time constant (12.5 s in this case) to as large as 600 s can be fully detailed in terms of both the thermodynamics and kinetics. In a binding titration scenario, in the most general case an injection can reveal an association rate constant (kon). Under more restrictive conditions, the instrument time constant-corrected power decay following each injection is simply an exponential decay described by a composite rate constant (kobs), from which both kon and the dissociation rate constant (koff) can be extracted. The data also support the viability of this exponential approach, for kon only, for a slightly larger set of conditions. Using a bimolecular RNA folding model and a protein-ligand interaction, we demonstrate and have internally validated this approach to experiment design, data processing, and error analysis. An updated guide to thermodynamic and kinetic regimes accessible by ITC is provided.

  7. Measuring Multivalent Binding Interactions by Isothermal Titration Calorimetry.

    PubMed

    Dam, Tarun K; Talaga, Melanie L; Fan, Ni; Brewer, Curtis F

    2016-01-01

    Multivalent glycoconjugate-protein interactions are central to many important biological processes. Isothermal titration calorimetry (ITC) can potentially reveal the molecular and thermodynamic basis of such interactions. However, calorimetric investigation of multivalency is challenging. Binding of multivalent glycoconjugates to proteins (lectins) often leads to a stoichiometry-dependent precipitation process due to noncovalent cross-linking between the reactants. Precipitation during ITC titration severely affects the quality of the baseline as well as the signals. Hence, the resulting thermodynamic data are not dependable. We have made some modifications to address this problem and successfully studied multivalent glycoconjugate binding to lectins. We have also modified the Hill plot equation to analyze high quality ITC raw data obtained from multivalent binding. As described in this chapter, ITC-driven thermodynamic parameters and Hill plot analysis of ITC raw data can provide valuable information about the molecular mechanism of multivalent lectin-glycoconjugate interactions. The methods described herein revealed (i) the importance of functional valence of multivalent glycoconjugates, (ii) that favorable entropic effects contribute to the enhanced affinities associated with multivalent binding, (iii) that with the progression of lectin binding, the microscopic affinities of the glycan epitopes of a multivalent glycoconjugate decrease (negative cooperativity), (iv) that lectin binding to multivalent glycoconjugates, especially to mucins, involves internal diffusion jumps, (bind and jump) and (v) that scaffolds of glycoconjugates influence their entropy of binding.

  8. A microfabrication-based approach to quantitative isothermal titration calorimetry.

    PubMed

    Wang, Bin; Jia, Yuan; Lin, Qiao

    2016-04-15

    Isothermal titration calorimetry (ITC) directly measures heat evolved in a chemical reaction to determine equilibrium binding properties of biomolecular systems. Conventional ITC instruments are expensive, use complicated design and construction, and require long analysis times. Microfabricated calorimetric devices are promising, although they have yet to allow accurate, quantitative ITC measurements of biochemical reactions. This paper presents a microfabrication-based approach to integrated, quantitative ITC characterization of biomolecular interactions. The approach integrates microfabricated differential calorimetric sensors with microfluidic titration. Biomolecules and reagents are introduced at each of a series of molar ratios, mixed, and allowed to react. The reaction thermal power is differentially measured, and used to determine the thermodynamic profile of the biomolecular interactions. Implemented in a microdevice featuring thermally isolated, well-defined reaction volumes with minimized fluid evaporation as well as highly sensitive thermoelectric sensing, the approach enables accurate and quantitative ITC measurements of protein-ligand interactions under different isothermal conditions. Using the approach, we demonstrate ITC characterization of the binding of 18-Crown-6 with barium chloride, and the binding of ribonuclease A with cytidine 2'-monophosphate within reaction volumes of approximately 0.7 µL and at concentrations down to 2mM. For each binding system, the ITC measurements were completed with considerably reduced analysis times and material consumption, and yielded a complete thermodynamic profile of the molecular interaction in agreement with published data. This demonstrates the potential usefulness of our approach for biomolecular characterization in biomedical applications.

  9. Common Standards of Basal Insulin Titration in T2DM

    PubMed Central

    Arnolds, Sabine; Heise, Tim; Flacke, Frank; Sieber, Jochen

    2013-01-01

    Type 2 diabetes mellitus has become a worldwide major health problem, and the number of people affected is steadily increasing. Thus, not all patients suffering from the disease can be treated by specialized diabetes centers or outpatient clinics, but by primary care physicians. The latter, however, might have time constraints and have to deal with many kinds of diseases or with multimorbid patients, so their focus is not so much on lowering high blood glucose values. Thus, the physicians, as well as the patients themselves, are often reluctant to initiate and adjust insulin therapy, although basal insulin therapy is considered the appropriate strategy after oral antidiabetic drug failure, according to the latest international guidelines. A substantial number of clinical studies have shown that insulin initiation and optimization can be managed successfully by using titration algorithms—even in cases where patients themselves are the drivers of insulin titration. Nevertheless, tools and strategies are needed to facilitate this process in the daily life of both primary health care professionals and patients with diabetes. PMID:23759411

  10. The photometric method of extrasolar planet detection revisited

    NASA Technical Reports Server (NTRS)

    Hale, Alan; Doyle, Laurance R.

    1994-01-01

    We investigate the geometry concerning the photometric method of extrasolar planet detection, i.e., the detection of dimunition of a parent star's brightness during a planetary transit. Under the assumption that planetary orbital inclinations can be defined by a Gaussian with a sigma of 10 deg centered on the parent star's equatorial plane, Monte Carlo simulations suggest that for a given star observed at an inclination of exactly 90 deg, the probability of at least one Earth-sized or larger planet being suitably placed for transits is approximately 4%. This probability drops to 3% for a star observed at an inclination of 80 deg, and is still approximately 0.5% for a star observed at an inclination of 60 deg. If one can select 100 stars with a pre-determined inclination equal or greater than 80 deg, the probability of at least one planet being suitably configured for transits is 95%. The majority of transit events are due to planets in small-a orbits similar to the Earth and Venus; thus, the photometric method in principle is the method best suited for the detection of Earthlike planets. The photometric method also allows for testing whether or not planets can exist within binary systems. This can ge done by selecting binary systems observed at high orbital inclinations, both eclipsing binaries and wider visual binaries. For a 'real-world' example, we look at the alpha Centauri system (i = 79.2 deg). If we assume that the equatorial planes of both components coincide with the system's orbital plane, Monte Carlo simulations suggest that the probability of at least one planet (of either component) being suitably configured for transits is approximately 8%. In conclusion, we present a non-exhaustive list of solar-type stars, both single and within binary systems, which exhibit a high equatorial inclination. These objects may be considered as preliminary candidates for planetary searches via the photometric method.

  11. Some photometric techniques for atmosphereless solar system bodies.

    PubMed

    Lumme, K; Peltoniemi, J; Irvine, W M

    1990-01-01

    We discuss various photometric techniques and their absolute scales in relation to the information that can be derived from the relevant data. We also outline a new scattering model for atmosphereless bodies in the solar system and show how it fits Mariner 10 surface photometry of the planet Mercury. It is shown how important the correct scattering law is while deriving the topography by photoclinometry. PMID:11538682

  12. Photometric analysis of Galactic Stellar Clusters in VVV Survey

    NASA Astrophysics Data System (ADS)

    Mauro, F.; Moni Bidin, C.; Cohen, R. E.; Geisler, D.; Villanova, S.; Chené, A. N.

    2014-10-01

    We show the preliminary results of the study of the structure of the Horizontal Branch of Liller 1 and some results from the Calcium Triplet method using Ks magnitude applied to several Galactic Globular clusters using data from the VISTA Variables in the Via Lactea Survey (Minniti et al. 2010) and obtained with GeMS/GSAOI. The data are extracted with the new automatic VVV-SkZ_pipeline photometric pipeline (Mauro et al. 2013).

  13. Photometric recording of transmembrane potential in outer hair cells

    NASA Astrophysics Data System (ADS)

    Nakagawa, Takashi; Oghalai, John S.; Saggau, Peter; Rabbitt, Richard D.; Brownell, William E.

    2006-06-01

    Cochlear outer hair cells (OHCs) are polarized epithelial cells that have mechanoelectrical transduction channels within their apical stereocilia and produce electromotile force along their lateral wall. Phase shifts, or time delays, in the transmembrane voltage occurring at different axial locations along the cell may contribute to our understanding of how these cells operate at auditory frequencies. We developed a method to optically measure the phase of the OHC transmembrane potential using the voltage-sensitive dye (VSD) di-8-ANEPPS. The exit aperture of a fibre-optic light source was driven in two dimensions so that a 24 µm spot of excitation light could be positioned along the length of the OHC. We used the whole-cell patch-clamp technique in the current-clamp mode to stimulate the OHC at the base. The photometric response and the voltage response were monitored with a photodetector and patch-clamp amplifier, respectively. The photometric response was used to measure the regional changes in the membrane potential in response to maintained (dc) and sinusoidal (ac) current stimuli applied at the base of the cell. We used a neutral density filter to lower the excitation light intensity and reduce phototoxicity. A sensitive detector and lock-in amplifier were used to measure the small ac VSD signal. This permitted measurements of the ac photometric response below the noise floor of the static fluorescence. The amplitude and phase components of the photometric response were recorded for stimuli up to 800 Hz. VSD data at 400-800 Hz show the presence of a small phase delay between the stimulus voltage at the base of the cell and the local membrane potential measured along the lateral wall. Results are consistent with the hypothesis that OHCs exhibit inhomogeneous membrane potentials that vary with position in analogy with the voltage in nerve axons.

  14. The Impact of Stochastic Attenuation on Photometric Redshift Estimates

    NASA Astrophysics Data System (ADS)

    Tepper-García, Thorsten; Fritze-von Alvensleben, Uta

    2007-05-01

    INTRODUCTION: We model the effect of the stochastic absorption by neutral hydrogen (HI) present in the intergalactic medium (IGM), such as Lyalpha Forest, and associated with galaxies (LLS, DLAs), on the photometric redshifts, and compare these results to the predicted photometric redshifts of models where only a mean attenuation is taken into account. METHODS: We model the attenuation due to HI along a random line of sight (LOS) using differential distribution functions constrained from observations (Kim et al. 97,01) in a Monte Carlo fashion (Bershady et al. 99). We then calculate galaxy model spectra of a given spectral type at different redshifts using our Evolutionary Synthesis Code GALEV (Bicker et al. 04), and apply to each spectrum a different attenuation corresponding to a particular random LOS. We obtain in this way an ensemble of attenuated spectral energy distributiond (SED) in the HST and Johnson systems. Using AnalySED (Anders et al. 06), an analysis tool based on a chi-square test, and our template SEDs with mean attenuation-which span a grid in redshift and spectral type-we determine to which extent the redshifts of our simulated spectra are recovered. RESULTS: We find a substantial underestimate of the photometric redshifts of up to Δz=0.3, especially in the range z > 3.0. DISCUSSION: Based on our results, we emphasise the need for the accurate modelling of the attenuation in order to correctly interpret, using evolutionary synthesis codes such as GALEV, the observations of (high-redshift) galaxies observed in deep surveys, for which only photometric information is available.

  15. A sparse Gaussian process framework for photometric redshift estimation

    NASA Astrophysics Data System (ADS)

    Almosallam, Ibrahim A.; Lindsay, Sam N.; Jarvis, Matt J.; Roberts, Stephen J.

    2016-01-01

    Accurate photometric redshifts are a lynchpin for many future experiments to pin down the cosmological model and for studies of galaxy evolution. In this study, a novel sparse regression framework for photometric redshift estimation is presented. Synthetic data set simulating the Euclid survey and real data from SDSS DR12 are used to train and test the proposed models. We show that approaches which include careful data preparation and model design offer a significant improvement in comparison with several competing machine learning algorithms. Standard implementations of most regression algorithms use the minimization of the sum of squared errors as the objective function. For redshift inference, this induces a bias in the posterior mean of the output distribution, which can be problematic. In this paper, we directly minimize the target metric Δz = (zs - zp)/(1 + zs) and address the bias problem via a distribution-based weighting scheme, incorporated as part of the optimization objective. The results are compared with other machine learning algorithms in the field such as artificial neural networks (ANN), Gaussian processes (GPs) and sparse GPs. The proposed framework reaches a mean absolute Δz = 0.0026(1 + zs), over the redshift range of 0 ≤ zs ≤ 2 on the simulated data, and Δz = 0.0178(1 + zs) over the entire redshift range on the SDSS DR12 survey, outperforming the standard ANNz used in the literature. We also investigate how the relative size of the training sample affects the photometric redshift accuracy. We find that a training sample of >30 per cent of total sample size, provides little additional constraint on the photometric redshifts, and note that our GP formalism strongly outperforms ANNz in the sparse data regime for the simulated data set.

  16. Microdensitometer errors: Their effect on photometric data reduction

    NASA Technical Reports Server (NTRS)

    Bozyan, E. P.; Opal, C. B.

    1984-01-01

    The performance of densitometers used for photometric data reduction of high dynamic range electrographic plate material is analyzed. Densitometer repeatability is tested by comparing two scans of one plate. Internal densitometer errors are examined by constructing histograms of digitized densities and finding inoperative bits and differential nonlinearity in the analog to digital converter. Such problems appear common to the four densitometers used in this investigation and introduce systematic algorithm dependent errors in the results. Strategies to improve densitometer performance are suggested.

  17. Precise chelatometric titrations of zinc, cadmium, and lead with molecular spectroscopy.

    PubMed

    Suzuki, Toshihiro; Tiwari, Diwakar; Hioki, Akiharu

    2007-10-01

    Spectral data during a chelatometric titration were utilized for determining an equivalence point of the titration. Three-dimensional titration data were analyzed by fitting to a theoretical equation that was derived from equilibrium equations among a metal ion, an indicator and EDTA. The equation with optimized parameters successfully explained the three-dimensional titration data. This method was applied to EDTA titration systems of zinc, cadmium and lead with xylenol orange (XO) as an indicator. These systems were analyzed while taking the formation of 1:1 and 2:1 metal-indicator complexes into account. By this method, an accurate equivalence point was determined as well as stability constants and molar absorption spectra of metal-indicator complexes in each titration system. Moreover, the comparability among the concentrations of the metal standard solutions prepared from pure metals (Zn, Pb, and Cd) was also confirmed by the proposed evaluation method.

  18. Photometric monitoring of the young star Par 1724 in Orion

    NASA Astrophysics Data System (ADS)

    Neuhäuser, R.; Koeltzsch, A.; Raetz, St.; Schmidt, T. O. B.; Mugrauer, M.; Young, N.; Bertoldi, F.; Roell, T.; Eisenbeiss, T.; Hohle, M. M.; Vaňko, M.; Ginski, C.; Rammo, W.; Moualla, M.; Broeg, C.

    2009-05-01

    We report new photometric observations of the ˜ 200 000 year old naked weak-line run-away T Tauri star Par 1724, located north of the Trapezium cluster in Orion. We observed in the broad band filters B, V, R, and I using the 90 cm Dutch telescope on La Silla, the 80 cm Wendelstein telescope, and a 25 cm telescope of the University Observatory Jena in Großschwabhausen near Jena. The photometric data in V and R are consistent with a ˜ 5.7 day rotation period due to spots, as observed before between 1960ies and 2000. Also, for the first time, we present evidence for a long-term 9 or 17.5 year cycle in photometric data (V band) of such a young star, a cycle similar to that to of the Sun and other active stars. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University; a telescope of the University Observatory Munich on Mount Wendelstein, the 0.9m ESO-Dutch telescope on La Silla, Chile, and with the All Sky Automated Survey (ASAS) project (www.astrouw.edu.pl/asas).

  19. Can Self-Organizing Maps Accurately Predict Photometric Redshifts?

    NASA Astrophysics Data System (ADS)

    Way, M. J.; Klose, C. D.

    2012-03-01

    We present an unsupervised machine-learning approach that can be employed for estimating photometric redshifts. The proposed method is based on a vector quantization called the self-organizing-map (SOM) approach. A variety of photometrically derived input values were utilized from the Sloan Digital Sky Survey's main galaxy sample, luminous red galaxy, and quasar samples, along with the PHAT0 data set from the Photo-z Accuracy Testing project. Regression results obtained with this new approach were evaluated in terms of root-mean-square error (RMSE) to estimate the accuracy of the photometric redshift estimates. The results demonstrate competitive RMSE and outlier percentages when compared with several other popular approaches, such as artificial neural networks and Gaussian process regression. SOM RMSE results (using Δz = zphot - zspec) are 0.023 for the main galaxy sample, 0.027 for the luminous red galaxy sample, 0.418 for quasars, and 0.022 for PHAT0 synthetic data. The results demonstrate that there are nonunique solutions for estimating SOM RMSEs. Further research is needed in order to find more robust estimation techniques using SOMs, but the results herein are a positive indication of their capabilities when compared with other well-known methods.

  20. A comprehensive photometric study of the eclipsing binary EP Aurigae

    NASA Astrophysics Data System (ADS)

    Li, H.-L.; Wei, J.-Y.; Yang, Y.-G.; Li, K.; Zhang, X.-B.

    2015-02-01

    We present new observations for the eclipsing binary EP Aurigae, which were performed by using three small telescopes in China from 2003 December to 2014 January. With the updated 2003 version of the Wilson-Devinney code, the photometric elements were deduced from three sets of light curves. Based on all available eclipsing times, the orbital period changes were investigated. It is discovered that the (O-C) curve may show an existence of light-time effect due to an unseen third body, which was weakly identified by the photometric solution. The modulated period and amplitude of the cyclic variation are P3=71.2(±8.0) yr and A=0.0101(±0.0008) day, respectively. In the co-planar orbit with the binary system, the mass of the third body is M3=0.18(±0.02) M⊙. The photometric results imply that EP Aur is an Algol-type binary with a mass ratio of q=0.831(±0.004). Its primary component almost fills its Roche lobe. Therefore, EP Aur may consist of a normal main-sequence star and a cool Roche-lobe filling subgiant, which may be undergoing rapid mass transfer.

  1. Photometric Study of the Possible Cool Quadruple System PY Virginis

    NASA Astrophysics Data System (ADS)

    Zhu, L. Y.; Qian, S. B.; Liu, N. P.; Liu, L.; Jiang, L. Q.

    2013-02-01

    Complete CCD photometric light curves in BV(RI)c bands obtained in 2012 for the short-period close binary system PY Virginis are presented. A new photometric analysis with the Wilson—Van Hamme code shows that PY Vir is an A-type marginal contact binary system. The absolute parameters of PY Vir are derived using spectroscopic and photometric solutions. Combining new determined times of minimum light with others published in the literature, the O - C diagram of the binary star is investigated. A periodic variation, with a period of 5.22(±0.05) years and an amplitude of 0.0075(±0.0004) days, was discovered. Since the spectrum of a third component has been detected by Rucinski et al., we consider this cyclic period oscillation to be the result of the light-time effect due to the presence of a third body. This third component may also be a binary itself. Therefore, PY Vir should be a quadruple system composed of two cool-type binary systems. This system is a good astrophysical laboratory to study the formation and evolution of close binaries and multiple systems.

  2. The Canada-France Deep Fields Photometric Redshift Survey

    NASA Astrophysics Data System (ADS)

    Brodwin, M.; Lilly, S. J.; McCracken, H. J.; Foucaud, S.; Le Fèvre, O.; Crampton, D.

    2002-12-01

    The Canada-France Deep Fields is a UBVRIZ imaging survey covering 1 deg2 to I ~ 25. A template-fitting photometric redshift algorithm has been developed and rigorously tested, producing redshifts with a dispersion of Δ z/(1+z) ~ 0.08 for galaxies at 0photometric redshift survey, calibrated with CFRS spectroscopy, was designed to study galaxy evolution since z ~ 1.3. With the full 3-D spatial information, real-space clustering and luminosity density evolution will be quantified over this redshift range. In this talk I will present the first results from the photometric redshift component of the survey.

  3. Photometric and polarimetric mapping of water turbidity and water depth

    NASA Technical Reports Server (NTRS)

    Halajian, J.; Hallock, H.

    1973-01-01

    A Digital Photometric Mapper (DPM) was used in the Fall of 1971 in an airborne survey of New York and Boston area waters to acquire photometric, spectral and polarimetric data. The object of this study is to analyze these data with quantitative computer processing techniques to assess the potential of the DPM in the measurement and regional mapping of water turbidity and depth. These techniques have been developed and an operational potential has been demonstrated. More emphasis is placed at this time on the methodology of data acquisition, analysis and display than on the quantity of data. The results illustrate the type, quantity and format of information that could be generated operationally with the DPM-type sensor characterized by high photometric stability and fast, accurate digital output. The prototype, single-channel DPM is suggested as a unique research tool for a number of new applications. For the operational mapping of water turbidity and depth, the merits of a multichannel DPM coupled with a laser system are stressed.

  4. ArborZ: PHOTOMETRIC REDSHIFTS USING BOOSTED DECISION TREES

    SciTech Connect

    Gerdes, David W.; Sypniewski, Adam J.; McKay, Timothy A.; Hao, Jiangang; Weis, Matthew R.; Wechsler, Risa H.; Busha, Michael T.

    2010-06-01

    Precision photometric redshifts will be essential for extracting cosmological parameters from the next generation of wide-area imaging surveys. In this paper, we introduce a photometric redshift algorithm, ArborZ, based on the machine-learning technique of boosted decision trees. We study the algorithm using galaxies from the Sloan Digital Sky Survey (SDSS) and from mock catalogs intended to simulate both the SDSS and the upcoming Dark Energy Survey. We show that it improves upon the performance of existing algorithms. Moreover, the method naturally leads to the reconstruction of a full probability density function (PDF) for the photometric redshift of each galaxy, not merely a single 'best estimate' and error, and also provides a photo-z quality figure of merit for each galaxy that can be used to reject outliers. We show that the stacked PDFs yield a more accurate reconstruction of the redshift distribution N(z). We discuss limitations of the current algorithm and ideas for future work.

  5. Photometric Observations of Transiting Planet Candidates With a Small Telescope

    NASA Astrophysics Data System (ADS)

    Stoker, Emily; Stephens, D.; Lara, P.; Ranquist, E.

    2013-10-01

    We are part of a ground based team that looks for transiting planets. Our collaborators' telescopes gather photometric data on thousands of stars each night, searching for any which show the small dip in brightness that may be indicative of a planet passing in front of the star. When such a candidate has been identified, it is put into a schedule for further photometric and radial velocity observations. We take follow-up photometric data with the 16-inch David Derrick telescope at the Orson Pratt Observatory at Brigham Young University (BYU). As the predicted drops in magnitude caused by transiting planets are often quite small, we have to determine the limits of this telescope - to see if it is sensitive enough to detect such minute changes in brightness or if there is enough inherent error to hide the transit. We present follow-up data taken with our telescope on several of the team's transiting planet candidates along with observations of known transiting planets to demonstrate the telescope's capabilities. We show the errors in photometry of our target objects and also include plots of stable ensemble stars to exhibit the level of variability that we see from imperfections in images and observing conditions. This research was funded in part by the Physics and Astronomy REU program at Brigham Young University during the summer of 2013.

  6. Photometric redshifts of 5000 Xray selected Stripe 82 sources

    NASA Astrophysics Data System (ADS)

    Tasnim Ananna, Tonima; Salvato, Mara; Urry, C. Megan; LaMassa, Stephanie M.; Stripe 82X Collaboration

    2016-01-01

    We present preliminary spectroscopic and photometric redshifts of 5000 X-ray-selected AGN sources from our Stripe 82X survey, which is designed to study rare high-redshift and/or high-luminosity AGN like the luminous quasars identified in the Sloan Digital Sky Survey but also including heavily reddened AGN not identified as such in SDSS. The sample covers a total of 31.3 deg2 in Stripe 82, a combination of 15.6 deg2 XMM AO13 data, 10.6 deg2 XMM AO10 and archival data, and 7.4 deg2 archival Chandra data. About 80% of the newly discovered X-ray sources have an optical counterpart in the co-added SDSS data; of these, roughly half have spectroscopic redshifts. We derived estimates of the photometric redshifts for the rest, using multiwavelength photometry from GALEX, SDSS, UKIDSS, VISTA, 2MASS, Spitzer, and WISE. The photometric redshifts will be used to determine the fraction of obscured black hole growth at high redshift and/or high luminosity, as well as to derive the evolving X-ray luminosity function and to measure AGN clustering in several redshift slices — information vital to understanding the co-evolution of galaxies and their central black holes.

  7. Photometric metallicity map of the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Choudhury, Samyaday; Subramaniam, Annapurni; Cole, Andrew A.

    2016-01-01

    We have estimated a metallicity map of the Large Magellanic Cloud (LMC) using the Magellanic Cloud Photometric Survey (MCPS) and Optical Gravitational Lensing Experiment (OGLE III) photometric data. This is a first of its kind map of metallicity up to a radius of 4°-5°, derived using photometric data and calibrated using spectroscopic data of Red Giant Branch (RGB) stars. We identify the RGB in the V, (V - I) colour-magnitude diagrams of small subregions of varying sizes in both data sets. We use the slope of the RGB as an indicator of the average metallicity of a subregion, and calibrate the RGB slope to metallicity using spectroscopic data for field and cluster red giants in selected subregions. The average metallicity of the LMC is found to be [Fe/H] = -0.37 dex (σ[Fe/H] = 0.12) from MCPS data, and [Fe/H] = -0.39 dex (σ[Fe/H] = 0.10) from OGLE III data. The bar is found to be the most metal-rich region of the LMC. Both the data sets suggest a shallow radial metallicity gradient up to a radius of 4 kpc (-0.049 ± 0.002 dex kpc-1 to -0.066 ± 0.006 dex kpc-1). Subregions in which the mean metallicity differs from the surrounding areas do not appear to correlate with previously known features; spectroscopic studies are required in order to assess their physical significance.

  8. The Photometric Performance and Calibration of WFPC2

    NASA Astrophysics Data System (ADS)

    Holtzman, Jon A.; Burrows, Christopher J.; Casertano, Stefano; Hester, J. Jeff; Trauger, John T.; Watson, Alan M.; Worthey, Guy

    1995-11-01

    We discuss the photometric performance and calibration of the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telesopce (HST). The stability and accuracy of WFPC2 photometric measurements is discussed, with particular attention given to charge transfer efficiency (CTE) effects, contamination effects in the ultraviolet (UV), and flat field accuracy and normalization. Observational data are presented from both WFPC2 observations and ground observations using a system similar to that flown. WFPC2 photometric systems are defined both for the ground and flight systems. Transformations between these systems and the Landolt UBVRI system are presented. These transformations are sensitive to details in the spectra being transformed, and these sensitivities are quantified and discussed. On-orbit observations are used to revise the prelaunch estimates of response curves to best match synthetic photometry results with observations, and the accuracy of the resulting synthetic photometry is discussed. Synthetic photometry is used to determine zeropoints and transformations for all of the fight filters, and also to derive interstellar extinction values for the WFPC2 system. Using stellar interior and atmosphere models, isochrones in the WFPC2 system are calculated and compared with several observations. (SECTION: Astronomical Instrumentation)

  9. Calibration of LSST Instrumental and Atmospheric Photometric Passbands

    SciTech Connect

    Burke, David L.; Axelrod, T.; Barrau, Aurelien; Baumont, Sylvain; Blondin, Stephane; Claver, Chuck; Gorecki, Alexia; Ivezic, Zeljko; Jones, Lynne; Krabbendam, Victor; Liang, Ming; Saha, Abhijit; Smith, Allyn; Smith, R.Chris; Stubbs, Christopher W.; /Harvard-Smithsonian Ctr. Astrophys.

    2011-07-06

    The Large Synoptic Survey Telescope (LSST) will continuously image the entire sky visible from Cerro Pachon in northern Chile every 3-4 nights throughout the year. The LSST will provide data for a broad range of science investigations that require better than 1% photometric precision across the sky (repeatability and uniformity) and a similar accuracy of measured broadband color. The fast and persistent cadence of the LSST survey will significantly improve the temporal sampling rate with which celestial events and motions are tracked. To achieve these goals, and to optimally utilize the observing calendar, it will be necessary to obtain excellent photometric calibration of data taken over a wide range of observing conditions - even those not normally considered 'photometric'. To achieve this it will be necessary to routinely and accurately measure the full optical passband that includes the atmosphere as well as the instrumental telescope and camera system. The LSST mountain facility will include a new monochromatic dome illumination projector system to measure the detailed wavelength dependence of the instrumental passband for each channel in the system. The facility will also include an auxiliary spectroscopic telescope dedicated to measurement of atmospheric transparency at all locations in the sky during LSST observing. In this paper, we describe these systems and present laboratory and observational data that illustrate their performance.

  10. Calibration of the MEarth Photometric System: Optical Magnitudes and Photometric Metallicity Estimates for 1802 Nearby M-Dwarfs

    NASA Astrophysics Data System (ADS)

    Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Newton, Elisabeth R.

    2016-02-01

    The MEarth Project is a photometric survey systematically searching the smallest stars near the Sun for transiting rocky planets. Since 2008, MEarth has taken approximately two million images of 1844 stars suspected to be mid-to-late M dwarfs. We have augmented this survey by taking nightly exposures of photometric standard stars and have utilized this data to photometrically calibrate the MEarth system, identify photometric nights, and obtain an optical magnitude with 1.5% precision for each M dwarf system. Each optical magnitude is an average over many years of data, and therefore should be largely immune to stellar variability and flaring. We combine this with trigonometric distance measurements, spectroscopic metallicity measurements, and 2MASS infrared magnitude measurements in order to derive a color-magnitude-metallicity relation across the mid-to-late M dwarf spectral sequence that can reproduce spectroscopic metallicity determinations to a precision of 0.1 dex. We release optical magnitudes and metallicity estimates for 1567 M dwarfs, many of which did not have an accurate determination of either prior to this work. For an additional 277 stars without a trigonometric parallax, we provide an estimate of the distance, assuming solar neighborhood metallicity. We find that the median metallicity for a volume-limited sample of stars within 20 pc of the Sun is [Fe/H] = -0.03 ± 0.008, and that 29/565 of these stars have a metallicity of [Fe/H] = -0.5 or lower, similar to the low-metallicity distribution of nearby G dwarfs. When combined with the results of ongoing and future planet surveys targeting these objects, the metallicity estimates presented here will be important for assessing the significance of any putative planet-metallicity correlation.

  11. A comparison of three methods for titration of poliovirus vaccines.

    PubMed

    Bey, E; Golombick, T

    1984-10-01

    Two methods for in vitro endpoint titration of poliovirus--the roller tube and the microtitration assay--were compared with each other and with the plaque assay, using secondary vervet monkey kidney cells and Vero cells as indicators. The roller tube method is the most reliable under difficult working conditions, but is otherwise cumbersome and expensive. The microtitre method is the most economical and the plaque assay the most sensitive. By suspending freshly trypsinized indicator cells with the virus dilutions before planting, it was possible to simplify the microtitre method considerably. The sensitivity of the plaque assay was improved for Vero cells by absorbing the virus onto freshly planted monolayers. The method was scaled down to a semi-micro level by using 24-well cell culture trays. The slower rate of plaque development under a low calcium overlay medium facilitated a more accurate plaque count.

  12. Analysis of an Oxygen Bleach: A Redox Titration Lab

    NASA Astrophysics Data System (ADS)

    Copper, Christine L.; Koubek, Edward

    2001-05-01

    An experiment is presented which allows students to balance an oxidation-reduction reaction equation and use the reaction to analyze a consumer product. The experiment calls for students to balance the reaction of H2O2 and MnO4- two different ways (one assuming that H2O2 is the oxygen source and a second assuming that MnO4- is the oxygen source). They then determine which of these balanced equations has the correct stoichiometry by titrating a standard H2O2 solution with KMnO4. Finally, they use the correct balanced equation to determine the mass percent of H2O2 in a commercially available, "environmentally friendly" oxygen bleach solution.

  13. Isothermal titration calorimetry of membrane proteins - progress and challenges.

    PubMed

    Rajarathnam, Krishna; Rösgen, Jörg

    2014-01-01

    Integral membrane proteins, including G protein-coupled receptors (GPCR) and ion channels, mediate diverse biological functions that are crucial to all aspects of life. The knowledge of the molecular mechanisms, and in particular, the thermodynamic basis of the binding interactions of the extracellular ligands and intracellular effector proteins is essential to understand the workings of these remarkable nanomachines. In this review, we describe how isothermal titration calorimetry (ITC) can be effectively used to gain valuable insights into the thermodynamic signatures (enthalpy, entropy, affinity, and stoichiometry), which would be most useful for drug discovery studies, considering that more than 30% of the current drugs target membrane proteins. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding.

  14. Isothermal titration calorimetry of ion-coupled membrane transporters.

    PubMed

    Boudker, Olga; Oh, SeCheol

    2015-04-01

    Binding of ligands, ranging from proteins to ions, to membrane proteins is associated with absorption or release of heat that can be detected by isothermal titration calorimetry (ITC). Such measurements not only provide binding affinities but also afford direct access to thermodynamic parameters of binding--enthalpy, entropy and heat capacity. These parameters can be interpreted in a structural context, allow discrimination between different binding mechanisms and guide drug design. In this review, we introduce advantages and limitations of ITC as a methodology to study molecular interactions of membrane proteins. We further describe case studies where ITC was used to analyze thermodynamic linkage between ions and substrates in ion-coupled transporters. Similar type of linkage analysis will likely be applicable to a wide range of transporters, channels, and receptors.

  15. Isothermal Titration Calorimetry: Assisted Crystallization of RNA-Ligand Complexes.

    PubMed

    Da Veiga, Cyrielle; Mezher, Joelle; Dumas, Philippe; Ennifar, Eric

    2016-01-01

    The success rate of nucleic acids/ligands co-crystallization can be significantly improved by performing preliminary biophysical analyses. Among suitable biophysical approaches, isothermal titration calorimetry (ITC) is certainly a method of choice. ITC can be used in a wide range of experimental conditions to monitor in real time the formation of the RNA- or DNA-ligand complex, with the advantage of providing in addition the complete binding profile of the interaction. Following the ITC experiment, the complex is ready to be concentrated for crystallization trials. This chapter describes a detailed experimental protocol for using ITC as a tool for monitoring RNA/small molecule binding, followed by co-crystallization. PMID:26227041

  16. Sailing on the "C": A Vitamin Titration with a Twist

    NASA Astrophysics Data System (ADS)

    Sowa, S.; Kondo, A. E.

    2003-05-01

    The experiment takes the traditional redox titration of vitamin C using iodine with starch as an indicator, and presents it to the student as a challenge in guided-inquiry format. Two versions, with different levels of difficulty, are provided, to accommodate students with varying levels of problem-solving skills. The "challenge" is both quantitative and qualitative: if you were an eighteenth-century sea captain packing for a voyage to the New World, would you take oranges, lemons, limes, or grapefruits to prevent your crew from getting scurvy? The challenge ties in history, nutrition, and health with chemistry, and provides students an opportunity to work with familiar food products in the laboratory.

  17. Ultrasonic and densimetric titration applied for acid-base reactions.

    PubMed

    Burakowski, Andrzej; Gliński, Jacek

    2014-01-01

    Classical acoustic acid-base titration was monitored using sound speed and density measurements. Plots of these parameters, as well as of the adiabatic compressibility coefficient calculated from them, exhibit changes with the volume of added titrant. Compressibility changes can be explained and quantitatively predicted theoretically in terms of Pasynski theory of non-compressible hydrates combined with that of the additivity of the hydration numbers with the amount and type of ions and molecules present in solution. It also seems that this development could be applied in chemical engineering for monitoring the course of chemical processes, since the applied experimental methods can be carried out almost independently on the medium under test (harmful, aggressive, etc.).

  18. Ultrasensitivity by Molecular Titration in Spatially Propagating Enzymatic Reactions

    PubMed Central

    Semenov, Sergey N.; Markvoort, Albert J.; Gevers, Wouter B.L.; Piruska, Aigars; de Greef, Tom F.A.; Huck, Wilhelm T.S.

    2013-01-01

    Delineating design principles of biological systems by reconstitution of purified components offers a platform to gauge the influence of critical physicochemical parameters on minimal biological systems of reduced complexity. Here we unravel the effect of strong reversible inhibitors on the spatiotemporal propagation of enzymatic reactions in a confined environment in vitro. We use micropatterned, enzyme-laden agarose gels which are stamped on polyacrylamide films containing immobilized substrates and reversible inhibitors. Quantitative fluorescence imaging combined with detailed numerical simulations of the reaction-diffusion process reveal that a shallow gradient of enzyme is converted into a steep product gradient by addition of strong inhibitors, consistent with a mathematical model of molecular titration. The results confirm that ultrasensitive and threshold effects at the molecular level can convert a graded input signal to a steep spatial response at macroscopic length scales. PMID:23972857

  19. Field-effect based attomole titrations in nanoconfinement.

    PubMed

    Veenhuis, Rogier B H; van der Wouden, Egbert J; van Nieuwkasteele, Jan W; van den Berg, Albert; Eijkel, Jan C T

    2009-12-21

    This paper describes a novel capacitive method to change the pH in micro- and nanofluidic channels. A device with two metal gate electrodes outside an insulating channel wall is used for this purpose. The device is operated at high ionic strength with thin double layers. We demonstrate that gate potentials applied between the electrodes cause a release or uptake of protons from the silicon nitride surface groups, resulting in a pH shift in the channel and a titration of solution compounds present. Due to the high quality silicon nitride insulating layer, the effect is purely capacitive and electrolysis can be neglected. Fluorescein was employed as a fluorescent pH indicator to quantify the induced pH changes, and a maximum change of 1.6 pH units was calculated. A linear relationship was found between applied potential and fluorescein intensity change, indicating a linear relation between actuated proton amount and applied voltage. Since this pH actuation method avoids redox reactions and can be operated at physiological ionic strength, it can be very useful as a "soft" way to change the pH in very small volumes e.g. in bioassays or cell-based research. The sensitivity of the optical detection method poses the only limit to the detectable amount of substance and the observed volume. In a preliminary measurement we show one possible application, namely titration of 100 attomol of TRIS in a 7 pL detection volume. It is important to stress that this pH actuation principle fundamentally differs from the pH changes occurring in ionic transistors which are due to counterion enrichment and coion exclusion, because it does not rely on double-layer overlap. As a result it can be operated at high ionic strength and in channels of up to at least 1 microm height.

  20. Cluster membership probabilities from proper motions and multi-wavelength photometric catalogues. I. Method and application to the Pleiades cluster

    NASA Astrophysics Data System (ADS)

    Sarro, L. M.; Bouy, H.; Berihuete, A.; Bertin, E.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Barrado, D.; Solano, E.

    2014-03-01

    Context. With the advent of deep wide surveys, large photometric and astrometric catalogues of literally all nearby clusters and associations have been produced. The unprecedented accuracy and sensitivity of these data sets and their broad spatial, temporal and wavelength coverage make obsolete the classical membership selection methods that were based on a handful of colours and luminosities. We present a new technique designed to take full advantage of the high dimensionality (photometric, astrometric, temporal) of such a survey to derive self-consistent and robust membership probabilities of the Pleiades cluster. Aims: We aim at developing a methodology to infer membership probabilities to the Pleiades cluster from the DANCe multidimensional astro-photometric data set in a consistent way throughout the entire derivation. The determination of the membership probabilities has to be applicable to censored data and must incorporate the measurement uncertainties into the inference procedure. Methods: We use Bayes' theorem and a curvilinear forward model for the likelihood of the measurements of cluster members in the colour-magnitude space, to infer posterior membership probabilities. The distribution of the cluster members proper motions and the distribution of contaminants in the full multidimensional astro-photometric space is modelled with a mixture-of-Gaussians likelihood. Results: We analyse several representation spaces composed of the proper motions plus a subset of the available magnitudes and colour indices. We select two prominent representation spaces composed of variables selected using feature relevance determination techniques based in Random Forests, and analyse the resulting samples of high probability candidates. We consistently find lists of high probability (p > 0.9975) candidates with ≈1000 sources, 4 to 5 times more than obtained in the most recent astro-photometric studies of the cluster. Conclusions: Multidimensional data sets require

  1. Electrochemical titration of the cytochrome hemes in the Rhodopseudomonas viridis reaction center. Cyclic equilibrium titrations yield midpoint potentials without evidence for heme cooperativity.

    PubMed

    Fritz, F; Moss, D A; Mäntele, W

    1992-02-01

    The redox and spectral characteristics of the 4-heme cytochrome c unit of the photochemical reaction center from Rhodopseudomonas viridis were studied by a combination of protein electrochemistry and spectroscopy using an ultra thin-layer spectroelectrochemical cell. Quantitative and reversible reduction of the high-potential and the low-potential hemes was performed in cyclic titrations to record the optical difference spectra in the alpha-band region. The titration of the absorbance from the high-potential hemes can be approximated with a sum of 2 Nernst functions with Em = 0.113 V and Em = 0.175 V. The corresponding titration of the absorbance from the low-potential hemes yielded Em = -0.257 V and Em = -0.175 V (all potentials quoted vs. Ag/AgC1/3 M KCl; add 0.208 V for potentials vs. standard hydrogen electrode). The high-potential hemes equilibrate rapidly and titrate identically for oxidative and reductive titrations. Under identical conditions, the low-potential hemes exhibit a hysteresis, thus indicating much slower equilibration with the applied potential. Cyclic titrations with increasing equilibration periods, however, indicate the disappearance of the hysteresis for equilibration periods approximately twice as long as for the high-potential hemes. We take this as evidence for a slower internal equilibration, but against a cooperativity of the low-potential hemes as observed for other multi-heme cytochromes.

  2. Photometric properties and scaling relations of early-type Brightest Cluster Galaxies

    NASA Astrophysics Data System (ADS)

    Liu, F. S.; Xia, X. Y.; Mao, Shude; Wu, Hong; Deng, Z. G.

    2008-03-01

    We investigate the photometric properties of the early-type Brightest Cluster Galaxies (BCGs) using a carefully selected sample of 85 BCGs from the C4 cluster catalogue with a redshift of less than 0.1. We perform accurate background subtractions and surface photometry for these BCGs to 25magarcsec-2 in the Sloan r band. By quantitatively analysing the gradient of the Petrosian profiles of BCGs, we find that a large fraction of BCGs have extended stellar envelopes in their outskirts; more luminous BCGs tend to have more extended stellar haloes that are likely to be connected with mergers. A comparison sample of elliptical galaxies was chosen with similar apparent magnitude and redshift ranges, for which the same photometric analysis procedure is applied. We find that BCGs have steeper size-luminosity (R ~ Lα) and Faber-Jackson (L ~ σβ) relations than the bulk of early-type galaxies. Furthermore, the power-law indices (α and β) in these relations increase as the isophotal limits become deeper. For isophotal limits from 22 to 25magarcsec-2, BCGs are usually larger than the bulk of early-type galaxies, and a large fraction (~49 per cent) of BCGs have discy isophotal shapes. The differences in the scaling relations are consistent with a scenario where the dynamical structure and formation route of BCGs may be different from the bulk of early-type galaxies; in particular dry (dissipationless) mergers may play a more important role in their formation. We highlight several possible dry merger candidates in our sample.

  3. A Laser-Pointer-Based Spectrometer for Endpoint Detection of EDTA Titrations

    ERIC Educational Resources Information Center

    Dahm, Christopher E.; Hall, James W.; Mattioni, Brian E.

    2004-01-01

    A laser spectrometer for the ethylenediaminetetra-acetic acid (EDTA) titration of magnesium or calcium ions that is designed around a handheld laser pointer as the source and a photoresistor as the detector is developed. Findings show that the use of the spectrometer reduces the degree of uncertainty and error in one part of the EDTA titrations,…

  4. Single-shot titrations and reaction monitoring by slice-selective NMR spectroscopy.

    PubMed

    Niklas, T; Stalke, D; John, M

    2015-01-25

    A new method, based on slice-selective NMR spectroscopy of inhomogeneous mixtures, is introduced to perform NMR titrations and reaction monitoring in a single experiment. The method was applied to the titration of a lithium salt with 12-crown-4, and to the reaction of nBuLi with N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDTA).

  5. [Sensitivity of methods of titration of the vaccine strain of porcine fever virus].

    PubMed

    Koritskaia, M A; Demkina, M M; Vlasova, A N

    2005-01-01

    Methods of titration of the CS vaccine strain of classical swine fever virus were compared in vitro and vivo. The titration in the TL and PK-15 cell culture without cytopathic effect is based on the detection of virus antigen by labeled antibodies. The infection intensity in the cell culture virtually correlated with the antigenic and immunogenic activity of dry vaccine used for swine.

  6. Comparative methods of titration of Silverwater virus, an arthropod borne virus.

    PubMed

    Belloncik, S; Boisvert, J

    1978-01-01

    Silverwater virus (SIL) was titrated in vivo and in vitro. Using a microculture technique, TCID50 was found to be much more sensitive than both the plaque forming assay and the LD50. The latter was the least sensitive mode of titration of Silverwater virus. The addition of DEAE dextran and trypsin to the viral inoculum increased the number and diameter of the plaques.

  7. Photometric Properties of Ceres and Comparisons with Previous HST Observations

    NASA Astrophysics Data System (ADS)

    Li, J.-Y.; Nathues, A.; Le Corre, L.; Reddy, V.; Sykes, M. V.; Hoffmann, M.; Mottola, S.; Schröder, S. E.; Longobardo, A.; Ciarniello, M.; McFadden, L. A.; Raymond, C. A.; Russell, C. T.

    2015-10-01

    NASA's Dawn spacecraft entered the first science orbit around its second target, dwarf planet Ceres, in April 2015. The photometric properties of Ceres not only reveal clues about the physical state of the regolith, surface composition, and geological history, but also are important for correcting the data collected under various observing and illumination geometries to a common geometry to facilitate the interpretations of all photometric and spectral data. The Dawn data collected during its approach to Ceres cover phase angles from a few degrees to ~155º, and almost cover the full range of incidence angles and emission angles from 0º to 90º, making an excellent dataset for studying the spectrophotometric properties of Ceres. We report the analysis of the photometric properties of Ceres in the visible wavelengths using the Framing Camera (FC) [1] data through all seven color filters and one clear filter, acquired during the approach and the Survey orbit of the mission. Although previous studies [2-4] suggested a remarkably uniform surface of Ceres, the images collected by Dawn during its approach to the target at a scale of a few km/pixel revealed some small but extremely bright spots and regions, with albedos up to >4 times the average albedo of Ceres, representing the highest contrast so far observed in all asteroids imaged from close distances by spacecraft missions. These bright spots should be geologically young, and might be related to the episodic water sublimation activity of Ceres [5-7]. We performed detailed comparisons of the albedos of these bright spots between previous Hubble Space Telescope (HST) observations and the Dawn observations that span about 10 years to search for any possible changes. By the time of preparing this abstract, the Dawn FChas collected images at pixel scale down to 2.1 km/pixel. By June 2015, the data with a scale of 0.4 km/pixel will have been collected during the Survey Orbit phase.

  8. Measuring redshift-space distortions using photometric surveys

    NASA Astrophysics Data System (ADS)

    Ross, Ashley J.; Percival, Will J.; Crocce, Martín; Cabré, Anna; Gaztañaga, Enrique

    2011-08-01

    We outline how redshift-space distortions (RSD) can be measured from the angular correlation function, w(θ), of galaxies selected from photometric surveys. The natural degeneracy between RSD and galaxy bias can be minimized by comparing results from bins with top-hat galaxy selection in redshift, and bins based on the radial position of galaxy pair centres. This comparison can also be used to test the accuracy of the photometric redshifts. The presence of RSD will be clearly detectable with the next generation of photometric redshift surveys. We show that the Dark Energy Survey (DES) will be able to measure f(z)σ8(z) to a 1σ accuracy of (17 ×b) per cent, using galaxies drawn from a single narrow redshift slice centred at z= 1. Here b is the linear bias, and f is the logarithmic rate of change of the linear growth rate with respect to the scalefactor. Extending to measurements of w(θ) for a series of bins of width 0.02(1 +z) over 0.5 < z < 1.4 will measure γ to a 1σ accuracy of 0.25, given the model f=Ωm(z)γ, and assuming a linear bias model that evolves such that b= 0.5 +z (and fixing other cosmological parameters). The accuracy of our analytic predictions is confirmed using mock catalogues drawn from simulations conducted by the Marenostrum Institut de Ciències de l'Espai Simulations (MICE) collaboration.

  9. Photometric modeling of viscous overstability in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Salo, H.

    2011-10-01

    The viscous overstability of dense planetary rings offers a plausible mechanism for the generation of observed ˜ 150 m radial density variations in the B and the inner A ring of Saturn (Colwell et al. 2007, Thomson et al. 2007). Viscous overstability, in the form of spontaneous growth of axisymmetric oscillations, arises naturally in N-body simulations, in the limit of high impact frequency and moderately weak selfgravity (Salo et al. 2001, Schmidt et al. 2001; see also Schmidt et al. 2009). For example, a selfgravitating system of identical particles with internal density ˜ half of solid ice, and following the Bridges et al. (1984) elasticity formula, becomes overstable for optical depths ? > 1, forming oscillations in about 100 meter scale. Like self-gravity wakes, with their typical ˜ 20° trailing pitch angle, overstable oscillations lead to a longitude-dependent brightness of the rings. Due to their axisymmetric nature, the expected longitude of minimum brightness is shifted to ring ansae. However, according to simulations, the axisymmetric oscillations may coexist with the inclined selfgravity wake structures, which can lead to complicated photometric behavior, depending on properties of the simulated system. The overstable systems may also exhibit amplitude modulations (in km-scales), arising from the mutual beating patterns of the basics overstable oscillations. New results of photometric modeling of viscously overstable dynamical simulations systems are reported, related to the above mentioned topics. The Monte Carlo method of Salo and Karjalainen (2003) is used, previously applied to modeling of photometric signatures of selfgravity wakes (Salo et al. 2004, French et al. 2007), scattering properties of propeller stuctures (Sremcevic et al., 2007), and to the intepretation of elevation-angle dependent opposition effect seen in HST data (Salo and French 2010). For example, the possible observable signatures of amplitude modulations are explored.

  10. New Asteroid Models Derived From Combined Photometric Data

    NASA Astrophysics Data System (ADS)

    Durech, Josef; Kaasalainen, M.; Warner, B. D.

    2007-10-01

    The lightcurve inversion method is a powerful tool for deriving asteroid physical models (spin states and shapes) from their disk-integrated photometry. A typical input data set for a main belt asteroid consists of tens of lightcurves from at least three apparitions. As has been shown by Kaasalainen (2004, A&A 422, L39), it is also possible to use calibrated photometry sparse in time. This approach has been tested on synthetic data sets with accuracy and cadence expected for the Pan-STARRS project (Durech et al. 2006, EM&P 97, 179). At present, new accurate photometric data are not yet available. However, it is possible to combine sparse photometry obtained during astrometric observations with a few dense lightcurves and in some cases derive new asteroid models from such combined data sets. We present about twenty new asteroid models derived from combined data sets. Dense lightcurves (the majority of them from the Uppsala Asteroid Photometric Catalogue) were combined with sparse photometric data from astrometric observations carried out at the US Naval Observatory in Flagstaff. The accuracy of the sparse photometry is about 0.08-0.1 mag, which is in some cases enough to derive a unique model. We have performed many tests that confirm credibility of our results and show typical uncertainties in the shape/pole/period determination. Although the shape models are coarse and may change with new data, the error in the pole direction is usually not higher than 20 deg of arc. In some cases, when the pole direction is not unique, the only physical parameters that can be determined are the rotation period and the ecliptic latitude of the spin axis.

  11. Precision photometric redshift calibration for galaxy-galaxy weak lensing

    NASA Astrophysics Data System (ADS)

    Mandelbaum, R.; Seljak, U.; Hirata, C. M.; Bardelli, S.; Bolzonella, M.; Bongiorno, A.; Carollo, M.; Contini, T.; Cunha, C. E.; Garilli, B.; Iovino, A.; Kampczyk, P.; Kneib, J.-P.; Knobel, C.; Koo, D. C.; Lamareille, F.; Le Fèvre, O.; Le Borgne, J.-F.; Lilly, S. J.; Maier, C.; Mainieri, V.; Mignoli, M.; Newman, J. A.; Oesch, P. A.; Perez-Montero, E.; Ricciardelli, E.; Scodeggio, M.; Silverman, J.; Tasca, L.

    2008-05-01

    Accurate photometric redshifts are among the key requirements for precision weak lensing measurements. Both the large size of the Sloan Digital Sky Survey (SDSS) and the existence of large spectroscopic redshift samples that are flux-limited beyond its depth have made it the optimal data source for developing methods to properly calibrate photometric redshifts for lensing. Here, we focus on galaxy-galaxy lensing in a survey with spectroscopic lens redshifts, as in the SDSS. We develop statistics that quantify the effect of source redshift errors on the lensing calibration and on the weighting scheme, and show how they can be used in the presence of redshift failure and sampling variance. We then demonstrate their use with 2838 source galaxies with spectroscopy from DEEP2 and zCOSMOS, evaluating several public photometric redshift algorithms, in two cases including a full p(z) for each object, and find lensing calibration biases as low as <1 per cent (due to fortuitous cancellation of two types of bias) or as high as 20 per cent for methods in active use (despite the small mean photoz bias of these algorithms). Our work demonstrates that lensing-specific statistics must be used to reliably calibrate the lensing signal, due to asymmetric effects of (frequently non-Gaussian) photoz errors. We also demonstrate that large-scale structure (LSS) can strongly impact the photoz calibration and its error estimation, due to a correlation between the LSS and the photoz errors, and argue that at least two independent degree-scale spectroscopic samples are needed to suppress its effects. Given the size of our spectroscopic sample, we can reduce the galaxy-galaxy lensing calibration error well below current SDSS statistical errors. Based in part on observations undertaken at the European Southern Observatory (ESO) Very Large Telescope (VLT) under Large Programme 175.A-0839. E-mail: rmandelb@ias.edu (RM); seljak@itp.uzh.ch (US) ‡ Hubble Fellow.

  12. Using Gamma Regression for Photometric Redshifts of Survey Galaxies

    NASA Astrophysics Data System (ADS)

    Elliott, J.; de Souza, R. S.; Krone-Martins, A.; Cameron, E.; Ishida, E. E. O.; Hilbe, J.

    Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a set of tools not commonly applied within astronomy, despite being widely used in other professions. With this technique, we achieve catastrophic outlier rates of the order of ˜ 1%, that can be achieved in a matter of seconds on large datasets of size ˜ 1,000,000. To make these techniques easily accessible to the astronomical community, we developed a set of libraries and tools that are publicly available.

  13. Infrared Imaging, Spectroscopic, and Photometric Studies of Comets

    NASA Technical Reports Server (NTRS)

    Gehrz, Robert D.

    1997-01-01

    We have continued our program of infrared (IR) photometric, imaging, spectroscopic, and polarimetric temporal observations of comets to study the properties of comet dust and comet nuclei. During the first two years we digitized our IR data base on P/Halley and other recent comets to facilitate further analysis and comparison with other data bases, and found compelling evidence for the emission of a burst of small grains from P/Halley's nucleus at perihelion. We reported imaging and photometric observations of Comets Austin 1990 V and Swift-Tuttle 1992. The Swift-Tuttle 1992t observations included IR photometry, several 7-14 micron long-slit spectra of the coma and a time-sequence of more than 150 10 micron broadband images of the coma. An analysis of near-IR images of the inner coma of P/Halley obtained on three consecutive nights in 1986 March showed sunwardjets. We completed our analysis of IR imaging spectrosco-photometric data on comets. We also obtained observations of Comets Hyakutake 1996 B2 and Hale/Bopp 1995 01. We obtained infrared imaging, photometric, spectroscopic and polarimetric temporal observations of bright comets using a network of five telescopes, with emphasis on simultaneous observations of comets at many wavelengths with different instruments. Our program offers several unique advantages: 1) rapid observational response to new comets with dedicated infrared telescopes; 2) observations within a few degrees of the sun when comets are near perihelion and 3) access to advanced infrared array imagers and spectrometers. In particular, reduction, analysis, publication and archiving of our Jupiter/sl-9 and Comet Hyakutake infrared data received special emphasis. Instrumentation development included installation of the latest version of the innovative FORTH telescope control and a data acquisition system that enables us to control three telescopes remotely by telephone from anywhere in the world for comet observations in broad daylight. We have

  14. KINEMATIC AND PHOTOMETRIC EVIDENCE FOR A BAR IN NGC 2683

    SciTech Connect

    Kuzio de Naray, Rachel; Zagursky, Matthew J.; McGaugh, Stacy S. E-mail: mzagursk@umd.edu

    2009-10-15

    We present optical long-slit and SparsePak Integral Field Unit emission line spectroscopy along with optical broadband and near-IR images of the edge-on spiral galaxy NGC 2683. We find a multi-valued, figure-of-eight velocity structure in the inner 45'' of the long-slit spectrum and twisted isovelocity contours in the velocity field. We also find, regardless of wavelength, that the galaxy isophotes are boxy. We argue that taken together, these kinematic and photometric features are evidence for the presence of a bar in NGC 2683. We use our data to constrain the orientation and strength of the bar.

  15. A photometric function for diffuse reflection by particulate materials

    NASA Technical Reports Server (NTRS)

    Meador, W. E.; Weaver, W. R.

    1975-01-01

    A photometric function is proposed to describe the diffuse reflection of radiation by particulate materials. Both multiple scattering and the dominant effects of particle shadowing are included and the function is verified by comparisons with the photometries of laboratory surfaces. Brightness measurements of planetary and other diffusely scattering surfaces can be used to calculate the brightness for geometries other than those used in the measurements and for which the Minnaert function does not apply. The measurements also can be directly related to such surface characteristics as particle size, single-particle albedo, and compactness.

  16. Characterizing the Photometric Response of the ANS Collaboration Monitoring Program

    NASA Astrophysics Data System (ADS)

    Munari, U.; Moretti, S.

    The ANS Collaboration uses the UBVR CI C filters from various commercial manufacturers (Omega Optical, Custom Scientific, Schuler, Optec, Astrodon) for its ongoing photometric monitoring of symbiotic stars. We measured their transmittance profiles over the range 2000 Å to 1.1 μ m for various operating conditions, and we are monitoring their evolution over time. Their field performance in terms of color equations has been evaluated by analyzing the transformations from local to standard system of the 14602 observing runs so far collected on symbiotic stars with the ANS Collaboration telescopes. Ageing effects, red leaks and transmittance vs. angle of incidence are also evaluated.

  17. Real time swallowing measurement system by using photometric stereo

    NASA Astrophysics Data System (ADS)

    Fujino, Masahiro; Kato, Kunihito; Mura, Emi; Nagai, Hajime

    2015-04-01

    In this paper, we propose a measurement system to evaluate the swallowing by estimating the movement of the thyroid cartilage. We developed a measurement system based on the vision sensor in order to achieve the noncontact and non-invasive sensor. The movement of the subject's thyroid cartilage is tracked by the three dimensional information of the surface of the skin measured by the photometric stereo. We constructed a camera system that uses near-IR light sources and three camera sensors. We conformed the effectiveness of the proposed system by experiments.

  18. Photometric correction of VIR high space resolution data of Ceres

    NASA Astrophysics Data System (ADS)

    Longobardo, Andrea; Palomba, Ernesto; De Sanctis, Maria Cristina; Ciarniello, Mauro; Tosi, Federico; Giacomo Carrozzo, Filippo; Capria, Maria Teresa; Zambon, Francesca; Raponi, Andrea; Ammannito, Eleonora; Zinzi, Angelo; Raymond, Carol; Russell, Christopher T.; VIR-Dawn Team

    2016-10-01

    NASA's Dawn spacecraft [1] has been orbiting Ceres since early 2015. The mission is divided into five stages, characterized by different spacecraft altitudes corresponding to different space resolutions, i.e. Approach (CSA), Rotational Characterization (CSR), Survey (CSS), High Altitude Mapping Orbit (HAMO), and Low Altitude Mapping Orbit (LAMO).Ceres is a dark body (i.e. average albedo at 1.2 um is 0.08 [2]), hence photometric correction is much more important than for brighter asteroids (e.g. S-type and achondritric). Indeed, the negligible role of multiple scattering increases the reflectance dependence on phase angle.A photometric correction of VIR data at low spatial resolution (i.e. CSA, CSR, CSS) has already been applied with different methodologies (e.g. [2], [3]), These techniques highlight a reflectance and band depths dependency on the phase angle which is homogeneous on the entire surface in agreement with C-type taxonomy.However, with increasing spatial resolution (i.e. HAMO and LAMO data), the retrieval of a unique set of parameters for the photometric correction is no longer sufficient to obtain reliable albedo/band depth maps. In this work, a new photometric correction is obtained and applied to all the high resolution VIR data of Ceres, taking into account the reflectance variations observed at small scales. The developed algorithm will be implemented on the MATISSE tool [4] in order to be visualized on the Ceres shape model.Finally, an interpretation of the obtained phase functions is given in terms of optical and physical properties of the Ceres regolith.AcknowledgementsVIR was funded and coordinated by the Italian Space Agency, and built by SELEX ES, with the scientific leadership of IAPS-INAF, Rome, Italy, and is operated by IAPS-INAF, Rome, Italy. Support of the Dawn Science, Instrument, and Operation Teams is gratefully acknowledged.References[1] Russell, C. T. et al., 2012, Science 336, 686[2] Longobardo A., et al., 2016, LPSC, 2239

  19. Tracing the sound horizon scale with photometric redshift surveys

    NASA Astrophysics Data System (ADS)

    Carnero-Rosell, A.; Sánchez, E.; García-Bellido, J.; Gaztañaga, E.; de Simoni, F.; Crocce, M.; Cabré, A.; Fosalba, P.; Alonso, D.

    2011-11-01

    We propose a novel method for the extraction of the baryonic acoustic oscillation scale in galaxy photometric surveys. The evolution of this scale can be used as a standard ruler in order to constrain cosmological parameters. The method consists in parametrize the angular correlation function ω(θ), with a simple analitical expresion, in order to extract the sound horizon scale. The method has been tested in the MICE simulation, one of the largest N-body simulation to date. We have considered projection effects, non-linearities and observational effects in our analysis, obtaining errors in cosmological parameters in agreement with what is expected in new generation surveys.

  20. Monitoring the Behavior of Star Spots Using Photometric Data

    NASA Astrophysics Data System (ADS)

    Ioannidis, P.; Schmitt, J. H. M. M.

    2015-01-01

    We use high accuracy photometric data to monitor the behavior of star spots . We develop an algorithm to determine the size and longitude of spots or spot groups, using Kepler light curves . Our algorithm separates the light curve in rotational-period sized intervals and calculates the size and longitude of the star spots by using limb darkened spot crossing models. The results can then be used to identify populations of spots, active regions on the stellar surface, mean spot lifetimes or even evidence for activity cycle evidences. To check the efficiency of our code we calculate the spot positions and sizes for the planet host star Kepler-210 .

  1. Photometric study of the binary system NN Del

    NASA Astrophysics Data System (ADS)

    Gómez-Forrellad, J. M.; Sánchez-Bajo, F.; Corbera-Subirana, M.; GarcÍa-Melendo, E.; Vidal-Sainz, J.

    We present the results of the differential V light curve analysis of NN Del. We show that NN Del is an EA eclipsing binary system with a period of 99.27 days and a highly eccentric orbit. Photometric solutions obtained using the Russell and the Wilson-Devinney models seem to indicate that both components are very similar in radii and luminosities (assuming a F5 spectral type). Constraints imposed on the V luminosity of the system by the HIPPARCOS data suggest that the components of the system could be subgiants instead of main sequence stars.

  2. Photometric Surveys of the Galactic Bulge and Long Bar

    NASA Astrophysics Data System (ADS)

    Gerhard, O.; Wegg, C.; Portail, M.

    The Galactic bar and box/peanut bulge can be studied in an unrivaled manner, star-by-star, with detailed chemical information and full 3D kinematics. Because of intervening dust this is greatly facilitated by the availability of wide field deep NIR photometric surveys. Here we summarize recent results on the three-dimensional structure of the bulge and the long bar region, based on 2MASS, UKIDSS, and particularly the ongoing VVV survey. We also summarize results from dynamical models for the Galactic bulge constructed with the Made-to-Measure method.

  3. Femtosecond broadband fluorescence upconversion spectroscopy: Improved setup and photometric correction

    SciTech Connect

    Zhang, X.-X.; Wuerth, C.; Resch-Genger, U.; Zhao, L.; Ernsting, N. P.; Sajadi, M.

    2011-06-15

    A setup for fluorescence upconversion spectroscopy (FLUPS) is described which has 80 fs temporal response (fwhm) for emission in the spectral range 425-750 nm. Broadband phase matching is achieved with tilted gate pulses at 1340 nm. Background from harmonics of the gate pulse is removed and sensitivity increased compared to previous designs. Photometric calibration of the upconversion process is performed with a set of fluorescent dyes. For Coumarin 153 in methanol the peak position, bandwidth, and asymmetry depending on delay time are reported.

  4. PHOTOMETRICALLY TRIGGERED KECK SPECTROSCOPY OF FERMI BL LACERTAE OBJECTS

    SciTech Connect

    Shaw, Michael S.; Romani, Roger W.

    2013-11-01

    We report on Keck spectra of 10 Fermi blazars. J0622+3326, previously unobserved, is shown to be a flat-spectrum radio quasar at redshift z = 1.062. The others are known BL Lac type objects that have resisted previous attempts to secure redshifts. Using a photometric monitoring campaign with the 0.76 m Katzman Automatic Imaging Telescope at Lick Observatory, we identified epochs when the relativistic jet emission was fainter than usual, thus triggering the Keck spectroscopy. This strategy gives improved sensitivity to stars and ionized gas in the host galaxy, thereby providing improved redshift constraints for seven of these sources.

  5. Macromolecular competition titration method accessing thermodynamics of the unmodified macromolecule-ligand interactions through spectroscopic titrations of fluorescent analogs.

    PubMed

    Bujalowski, Wlodzimierz; Jezewska, Maria J

    2011-01-01

    Analysis of thermodynamically rigorous binding isotherms provides fundamental information about the energetics of the ligand-macromolecule interactions and often an invaluable insight about the structure of the formed complexes. The Macromolecular Competition Titration (MCT) method enables one to quantitatively obtain interaction parameters of protein-nucleic acid interactions, which may not be available by other methods, particularly for the unmodified long polymer lattices and specific nucleic acid substrates, if the binding is not accompanied by adequate spectroscopic signal changes. The method can be applied using different fluorescent nucleic acids or fluorophores, although the etheno-derivatives of nucleic acid are especially suitable as they are relatively easy to prepare, have significant blue fluorescence, their excitation band lies far from the protein absorption spectrum, and the modification eliminates the possibility of base pairing with other nucleic acids. The MCT method is not limited to the specific size of the reference nucleic acid. Particularly, a simple analysis of the competition titration experiments is described in which the fluorescent, short fragment of nucleic acid, spanning the exact site-size of the protein-nucleic acid complex, and binding with only a 1:1 stoichiometry to the protein, is used as a reference macromolecule. Although the MCT method is predominantly discussed as applied to studying protein-nucleic acid interactions, it can generally be applied to any ligand-macromolecule system by monitoring the association reaction using the spectroscopic signal originating from the reference macromolecule in the presence of the competing macromolecule, whose interaction parameters with the ligand are to be determined.

  6. Molecular Titration Promotes Oscillations and Bistability in Minimal Network Models with Monomeric Regulators.

    PubMed

    Cuba Samaniego, Christian; Giordano, Giulia; Kim, Jongmin; Blanchini, Franco; Franco, Elisa

    2016-04-15

    Molecular titration is emerging as an important biochemical interaction mechanism within synthetic devices built with nucleic acids and the CRISPR/Cas system. We show that molecular titration in the context of feedback circuits is a suitable mechanism to enhance the emergence of oscillations and bistable behaviors. We consider biomolecular modules that can be inhibited or activated by input monomeric regulators; the regulators compete with constitutive titrating species to determine the activity of their target. By tuning the titration rate and the concentration of titrating species, it is possible to modulate the delay and convergence speed of the transient response, and the steepness and dead zone of the stationary response of the modules. These phenomena favor the occurrence of oscillations when modules are interconnected to create a negative feedback loop; bistability is favored in a positive feedback interconnection. Numerical simulations are supported by mathematical analysis showing that the capacity of the closed loop systems to exhibit oscillations or bistability is structural.

  7. Simple modification of karl-Fischer titration method for determination of water content in colored samples.

    PubMed

    Tavčar, Eva; Turk, Erika; Kreft, Samo

    2012-01-01

    The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes place in a sealed 4 ml cuvette. Detection is performed at 520 nm. Titration endpoint is determined from the graph of absorbance plotted against titration volume. The method has appropriate reproducibility (RSD = 4.3%), accuracy, and linearity (R(2) = 0.997).

  8. Using RNA sample titrations to assess microarray platform performance and normalization techniques.

    PubMed

    Shippy, Richard; Fulmer-Smentek, Stephanie; Jensen, Roderick V; Jones, Wendell D; Wolber, Paul K; Johnson, Charles D; Pine, P Scott; Boysen, Cecilie; Guo, Xu; Chudin, Eugene; Sun, Yongming Andrew; Willey, James C; Thierry-Mieg, Jean; Thierry-Mieg, Danielle; Setterquist, Robert A; Wilson, Mike; Lucas, Anne Bergstrom; Novoradovskaya, Natalia; Papallo, Adam; Turpaz, Yaron; Baker, Shawn C; Warrington, Janet A; Shi, Leming; Herman, Damir

    2006-09-01

    We have assessed the utility of RNA titration samples for evaluating microarray platform performance and the impact of different normalization methods on the results obtained. As part of the MicroArray Quality Control project, we investigated the performance of five commercial microarray platforms using two independent RNA samples and two titration mixtures of these samples. Focusing on 12,091 genes common across all platforms, we determined the ability of each platform to detect the correct titration response across the samples. Global deviations from the response predicted by the titration ratios were observed. These differences could be explained by variations in relative amounts of messenger RNA as a fraction of total RNA between the two independent samples. Overall, both the qualitative and quantitative correspondence across platforms was high. In summary, titration samples may be regarded as a valuable tool, not only for assessing microarray platform performance and different analysis methods, but also for determining some underlying biological features of the samples.

  9. Simple Modification of Karl-Fischer Titration Method for Determination of Water Content in Colored Samples

    PubMed Central

    Tavčar, Eva; Turk, Erika; Kreft, Samo

    2012-01-01

    The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes place in a sealed 4 ml cuvette. Detection is performed at 520 nm. Titration endpoint is determined from the graph of absorbance plotted against titration volume. The method has appropriate reproducibility (RSD = 4.3%), accuracy, and linearity (R2 = 0.997). PMID:22567558

  10. Nonaqueous potentiometric titration and elemental analysis of high-boiling distillates of Saudi Arabian crude oils

    SciTech Connect

    Ali, M.F.; Ali, M.A. )

    1988-12-01

    Nonaqueous potentiometric titration and elemental analysis were used to study basic and nonbasic functionalities present in high-boiling distillates of four Saudi Arabian crude oils. Model nitrogen compounds were titrated under similar titration conditions to differentiate them into strong, weak and nonbasic species. The strong bses titrated were due to the presence of of pyridine and its benzologs like acridines, phenanthridines and quionolines. The weak bases titrated were due to phenazxines and amides whereas the pyrroles, indoles and carbazoles were found to be nonbasic in nature. The total nitrogen and the total basic nitrogen compounds were generally found to be in very low concentration in the four crude oil distillates. A gradual decrease in the basicity of the distillates was found from Arab Heavy to Arab Extra Light through Arab Medium and Arab Light crude oils.

  11. Integration and global analysis of isothermal titration calorimetry data for studying macromolecular interactions.

    PubMed

    Brautigam, Chad A; Zhao, Huaying; Vargas, Carolyn; Keller, Sandro; Schuck, Peter

    2016-05-01

    Isothermal titration calorimetry (ITC) is a powerful and widely used method to measure the energetics of macromolecular interactions by recording a thermogram of differential heating power during a titration. However, traditional ITC analysis is limited by stochastic thermogram noise and by the limited information content of a single titration experiment. Here we present a protocol for bias-free thermogram integration based on automated shape analysis of the injection peaks, followed by combination of isotherms from different calorimetric titration experiments into a global analysis, statistical analysis of binding parameters and graphical presentation of the results. This is performed using the integrated public-domain software packages NITPIC, SEDPHAT and GUSSI. The recently developed low-noise thermogram integration approach and global analysis allow for more precise parameter estimates and more reliable quantification of multisite and multicomponent cooperative and competitive interactions. Titration experiments typically take 1-2.5 h each, and global analysis usually takes 10-20 min.

  12. [Simultaneous determination of calcium and magnesium by calculative spectrophotometric complexometric titration].

    PubMed

    Liao, Li-fu; Xiao, Xi-lin; Yang, Ming-hui; Yang, Jing

    2007-12-01

    A new spectrophotometric complexometric titration method coupled with chemometrics for the determination of mixtures of metal ions has been developed. In the method described here, the titrant is a mixture of EDTA and two indicators. In the process of titration, both the volumetric addition of titrant and the progress of titration reaction can be characterized simultaneously by chemometric calculation with the absorption spectra, and then the titration curves can be obtained. With the titration curves, a matrix equation can be established, and thus the concentration of each component in the mixture of metal ions can be calculated with principal component regression. The method only needs the information of absorption spectra to obtain the analytical results, and is free of volumetric measurements. So the method is simple, convenient and precise, and has been applied to the simultaneous determination of mixtures of calcium and magnesium using malachite green and Cu-PAN as indicators with satisfactory results.

  13. Documentation for the machine-readable version of photometric data for nearby stars

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.

    1982-01-01

    A computer list of all photometric systems (of those considered), in which each star was measured is provided. The file is a subset of a much larger and more comprehensive compilation, which lists all measured photoelectric photometric systems for any star that has been measured in at least one photoelectric system. In addition to the photometric system identifications, cross identifications to the Henry Draper and Durchmusterung catalogs and apparent visual magnitudes are included.

  14. Acid-base titrations by stepwise addition of equal volumes of titrant with special reference to automatic titrations-III Presentation of a fully automatic titration apparatus and of results supporting the theories given in the preceding parts.

    PubMed

    Pehrsson, L; Ingman, F

    1977-02-01

    This paper forms Part III of a series in which the first two parts describe methods for evaluating titrations performed by stepwise addition of equal volumes of titrant. The great advantage of these methods is that they do not require an accurate calibration of the electrode system. This property makes the methods very suitable for routine work. e.g., in automatic analysis. An apparatus for performing such titrations automatically is presented. Further, results of titrations of monoprotic acids, a diprotic acid, an ampholyte, a mixture of an acid with its conjugate base, and mixtures of two acids with a small difference between the stability constants are given. Most of these titrations cannot be evaluated by the Gran or Hofstee methods but yield results having errors of the order of 0.1% if the methods proposed in Parts I and II of this series are employed. The advantages of the method of stepwise addition of equal volumes of titrant combined with the proposed evaluation methods, in comparison with common methods such as titration to a preset pH, are that all the data are used in the evaluation, permitting a statistical treatment and giving better possibilities for tracing systematic errors.

  15. Determination of vanadium(V) by direct automatic potentiometric titration with EDTA using a chemically modified electrode as a potentiometric sensor.

    PubMed

    Quintar, S E; Santagata, J P; Cortinez, V A

    2005-10-15

    A chemically modified electrode (CME) was prepared and studied as a potentiometric sensor for the end-point detection in the automatic titration of vanadium(V) with EDTA. The CME was constructed with a paste prepared by mixing spectral-grade graphite powder, Nujol oil and N-2-naphthoyl-N-p-tolylhydroxamic acid (NTHA). Buffer systems, pH effects and the concentration range were studied. Interference ions were separated by applying a liquid-liquid extraction procedure. The CME did not require any special conditioning before using. The electrode was constructed with very inexpensive materials and was easily made. It could be continuously used, at least two months without removing the paste. Automatic potentiometric titration curves were obtained for V(V) within 5 x 10(-5) to 2 x 10(-3)M with acceptable accuracy and precision. The developed method was applied to V(V) determination in alloys for hip prosthesis. PMID:18970248

  16. Initial Evaluation of a Titration Appliance for Temporary Treatment of Obstructive Sleep Apnea

    PubMed Central

    Levendowski, Daniel J.; Morgan, Todd; Westbrook, Philip

    2015-01-01

    Background Custom oral appliances that adjustably advance the mandible provide superior outcomes when treating patients with moderate or severe sleep apnea. Custom appliances, however, are expensive, must be fitted by a dentist, and the likelihood of successful outcomes are difficult to predict. An inexpensive trial appliance, if proven efficacious, might be used to predict custom appliance outcomes or to provide temporary therapeutic benefit. Objective The aim of this initial study was to assess the treatment efficacy of a novel titration oral appliance with that of an optimized custom appliance. Methods Seventeen patients, treated with a custom oral appliance for at least one year, successfully completed a three-night home sleep test. The baseline obstructive sleep apnea severity was established on Night 1 with seven patients exhibiting severe, six moderate and four mild apnea/hypopnea indexes. Patients were randomly assigned to wear their custom appliance or the titration appliance on Nights 2 and 3. Results Significant reductions in the mean overall and supine apnea indexes (p < 0.05), and the overall (p < 0.01) and supine (p < 0.05) apnea/hypopnea indexes were observed for both the titration and custom appliances. The proportion of patients who exhibited at least a 50% reduction in the overall apnea index and supine apnea/hypopnea were similar for the titration and custom appliance (~60%). The custom appliance reduced the overall apnea/hypopnea index by 50% in a greater proportion of the patients compared to the titration appliance (77% vs. 53%). The titration appliance significantly reduced the degree of hypoxic exposure across sleep disordered breathing events overall (p < 0.05) and supine (p < 0.01). Patients found their custom appliance was more comfortable than the titration appliance, but preferred the titration appliance to no therapy. Conclusion The titration appliance may be useful in assessing oral appliance treatment efficacy. When set to 70% of

  17. A colorimetric LDH assay for the titration of infectivity and the evaluation of anti-viral activity against ortho- and paramyxoviruses.

    PubMed

    Mori, S; Watanabe, W; Shigeta, S

    1995-12-01

    A rapid and precise screening assay was developed for in vitro evaluation of anti-orthomyxo- and anti-paramyxovirus agents. The procedure is spectrophotometrical assessment for viability of cells via extracellular leakage of lactic dehydrogenase (LDH). HMV-II cells, a human melanoma cell line was found to be suitable for the titration of virus infectivity and screening of anti-viral agents for orthomyxo- and paramyxoviruses. Comparative titration of infectivity of stock viruses by the LDH and the MTT in site reduction of 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) methods with HMV-II cells as well as plaque titration with MDCK, Vero and HeLa cells was carried out. The LDH method was comparable or more sensitive for influenza viruses (FLUV)-A, B, C, parainfluenza viruses (PFLUV)-1, 2 and less sensitive for PFLUV-3, mumps virus (MPSV), measles viruses (MLSV) and respiratory syncytial virus (RSV) than the plaque titration. The 50% effective concentration (EC50) of 1-beta-D-ribofuranosyl-1, 2, 4-triazol-3-carboxamide (ribavirin) and 5-ethynyl-1-beta-D-ribofuranosyl-imidazole-4-carboxamide (EICAR) against orthomyxo- and paramyxoviruses were examined comparatively by the LDH, MTT and plaque reduction (PR) methods. The EC50 values of FLUV-C and PFLUV-1 were able to be evaluated only by the LDH but not by the MTT and PR methods. The LDH method with HMV-II cells simplifies the assay procedure and permits the evaluation of a large number of compounds for anti-orthomyxo- and anti-paramyxoviruses activity in vitro.

  18. On the photometric axis of the zodiacal light

    NASA Technical Reports Server (NTRS)

    Misconi, N. Y.

    1977-01-01

    A model of the zodiacal cloud is used to predict the position of the photometric axis (the locus of points of maximum brightness) of the zodiacal light at any elongation angle from the sun for any time of the year for various symmetry planes: the orbital planes of Venus, Mars, and Jupiter, the invariable plane, and the solar equatorial plane. Using a scattering function which combines isotropic scattering and Fresnel reflection, the geocentric distance of the dust that contributes most of the brightness at each elongation angle is determined by computing the brightness contribution along the line of sight. A comparison of the predicted and observed positions shows that at elongation angles of 15 to 60 deg, the axis of symmetry appears to be close to the orbital plane of Venus. At angles of less than 10 deg, it is difficult to distinguish among the proposed planes of symmetry. Observations of the photometric axis at angles of 60 to 180 deg are scarce and do not permit precise determination of the axis of symmetry in that region.

  19. A PHOTOMETRICALLY AND MORPHOLOGICALLY VARIABLE INFRARED NEBULA IN L483

    SciTech Connect

    Connelley, Michael S.; Hodapp, Klaus W.; Fuller, Gary A.

    2009-03-15

    We present narrow and broad K-band observations of the Class 0/I source IRAS 18148-0440 that span 17 years. The infrared nebula associated with this protostar in the L483 dark cloud is both morphologically and photometrically variable on a timescale of only a few months. This nebula appears to be an infrared analog to other well known optically visible variable nebulae associated with young stars, such as Hubble's Variable Nebula. Along with Cepheus A, this is one of the first large variable nebulae to be found that is only visible in the infrared. The variability of this nebula is most likely due to changing illumination of the cloud rather than any motion of the structure in the nebula. Both morphological and photometric changes are observed on a timescale only a few times longer than the light crossing time of the nebula, suggesting very rapid intrinsic changes in the illumination of the nebula. Our narrowband observations also found that H{sub 2} knots are found nearly twice as far to the east of the source as to its west, and that H{sub 2} emission extends farther east of the source than the previously known CO outflow.

  20. The photometric properties of galaxies in the early Universe

    NASA Astrophysics Data System (ADS)

    Wilkins, Stephen M.; Feng, Yu; Di-Matteo, Tiziana; Croft, Rupert; Stanway, Elizabeth R.; Bunker, Andrew; Waters, Dacen; Lovell, Christopher

    2016-08-01

    We use the large cosmological hydro-dynamic simulation BLUETIDES to predict the photometric properties of galaxies during the epoch of reionization (z = 8-15). These properties include the rest-frame UV to near-IR broad-band spectral energy distributions, the Lyman continuum (LyC) photon production, the UV star formation rate calibration, and intrinsic UV continuum slope. In particular we focus on exploring the effect of various modelling assumptions, including the assumed choice of stellar population synthesis (SPS) model, initial mass function, and the escape fraction of LyC photons, upon these quantities. We find that these modelling assumptions can have a dramatic effect on photometric properties leading to consequences for the accurate determination of physical properties from observations. For example, at z = 8 we predict that nebular emission can account for up to 50 per cent of the rest-frame R-band luminosity, while the choice of SPS model can change the LyC production rate up to a factor of ×2.

  1. Spectrometric and photometric study of the eclipsing variable AM Leo

    NASA Astrophysics Data System (ADS)

    Gorda, S. Yu.

    2016-01-01

    The results of quasi-simultaneous spectroscopic and photometric observations of a W UMatype eclipsing variable star AM Leo are presented. The observations were carried out with a 1.2-m telescope equipped with a high-resolution echelle spectrometer, and a telescope-reflector ( D = 0.45m) of the Kourovka Astronomical Observatory of Ural Federal University. New values of semi-amplitudes of the radial velocity curves of the components, K 1 = 109.6kms-1 and K 2 = 252.4kms-1 and the systemic radial velocity V 0 =-9.3 kms-1 are obtained, comparable to the data published in the literature. The semi-amplitude of the radial velocity curve of a more massive component K 1 and the mass ratio of the components q = 0.412 appeared to be slightly smaller than the values obtained by other authors. An assumption wasmade that a possible reason of this is the presence of hot and/or cold spots on the surface of the components, shifting the effective center of brightness of the visible disk of the component with respect to its center of mass position. It was shown that the AM Leo light curve variations on the time scales of one and more days, registered within the photometric part of the study may be described by the choice of appropriate model of the spot structure.

  2. Asteroid models from combined sparse and dense photometric data

    NASA Astrophysics Data System (ADS)

    Durech, J.; Kaasalainen, M.; Warner, B. D.; Fauerbach, M.; Marks, S. A.; Fauvaud, S.; Fauvaud, M.; Vugnon, J.-M.; Pilcher, F.; Bernasconi, L.; Behrend, R.

    2009-01-01

    Aims: Shape and spin state are basic physical characteristics of an asteroid. They can be derived from disc-integrated photometry by the lightcurve inversion method. Increasing the number of asteroids with known basic physical properties is necessary to better understand the nature of individual objects as well as for studies of the whole asteroid population. Methods: We use the lightcurve inversion method to obtain rotation parameters and coarse shape models of selected asteroids. We combine sparse photometric data from the US Naval Observatory with ordinary lightcurves from the Uppsala Asteroid Photometric Catalogue and the Palmer Divide Observatory archive, and show that such combined data sets are in many cases sufficient to derive a model even if neither sparse photometry nor lightcurves can be used alone. Our approach is tested on multiple-apparition lightcurve inversion models and we show that the method produces consistent results. Results: We present new shape models and spin parameters for 24 asteroids. The shape models are only coarse but describe the global shape characteristics well. The typical error in the pole direction is ~10-20°. For a further 18 asteroids, inversion led to a unique determination of the rotation period but the pole direction was not well constrained. In these cases we give only an estimate of the ecliptic latitude of the pole.

  3. A photometric catalogue of southern emission-line stars

    NASA Astrophysics Data System (ADS)

    de Winter, D.; van den Ancker, M. E.; Maira, A.; Thé, P. S.; Djie, H. R. E. Tjin A.; Redondo, I.; Eiroa, C.; Molster, F. J.

    2001-12-01

    We present a catalogue of previously unpublished optical and infrared photometry for a sample of 162 emission-line objects and shell stars visible from the southern hemisphere. The data were obtained between 1978 and 1997 in the Walraven (WULBV), Johnson/Cousins (UBV(RI)c) and ESO and SAAO near-infrared (JHKLM) photometric systems. Most of the observed objects are Herbig Ae/Be (HAeBe) stars or HAeBe candidates appearing in the list of HAeBe candidates of Thé et al. (1994), although several B[e] stars, LBVs and T Tauri stars are also included in our sample. For many of the stars the data presented here are the first photo-electric measurements in the literature. The resulting catalogue consists of 1809 photometric measurements. Optical variability was detected in 66 out of the 116 sources that were observed more than once. 15 out of the 50 stars observed multiple times in the infrared showed variability at 2.2 mu m (K band). Based on observations collected at the European Southern Observatory, La Silla, Chile and on observations collected at the South African Astronomical Observatory. Tables 2-4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http:/ /cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/380/609

  4. Photoelectric Standards of the Strömvil Photometric System

    NASA Astrophysics Data System (ADS)

    Straižys, V.; Kazlauskas, A.; Boyle, R. P.; Philip, A. G. D.; Sperauskas, J.

    2000-12-01

    In order to calibrate the Strömvil Photometric System, proposed by V. Straižys et al., Baltic Astronomy, 5, 83, 1996, the first run of the photoelectric observations was carried out by using a new two-channel photometer. The observations were done in February-April, 2000 with the 60" telescope of Steward Observatory on Mt. Lemmon. About 200 stars (mostly with well defined distances from the Hipparcos mission and knowm effective temperatures) of various spectral and luminosity classes were observed with the purpose to test the classification possibilities and to calibrate the new system. Another part of our observations included more than 100 stars in the standard areas for CCD photometry, proposed by A. G. D. Philip et al., Baltic Astronomy, 5, 445, 1996. They include open clusters M67 and M37, globular clusters M3 and M92 and some other fields, where CCD observations in the Strömvil photometric system have been obtained earlier. Note: ITPA -- Institute of Theoretical Physics and Astronomy, Vilnius, Lithuania, ISO -- Institute for Space Observations, Schenectady, N.Y.

  5. Photometric Analysis of the Overcontact Binary CW Cas

    NASA Astrophysics Data System (ADS)

    Wang, J. J.; Qian, S. B.; He, J. J.; Li, L. J.; Zhao, E. G.

    2014-11-01

    New CCD photometric observations of overcontact binary CW Cas were carried out in 2004 and 2011. In particular, the light curve obtained in 2004 shows a remarkable O'Connell effect. Compared with light curves in different observing seasons, variations were found. These variations can be explained by dark spot activities on the surface of at least one component. Using the Wilson-Devinney code with a spot model, we find that the photometric solutions confirm CW Cas is a shallow W-subtype overcontact binary with a spotted massive component. Our new determined times of minimum light together with the others published in the literature were analyzed to find a change of orbital period. From the O - C curves, the period of the system shows a cyclic period change (P 3 = 69.9 yr, A 3 = 0.03196 days) superposed on the linear increase. The cyclic variation, if explained as the light-travel time effect, reveals the presence of a tertiary companion.

  6. Photometric Mapping of Asteroid (4) Vesta from HST

    NASA Astrophysics Data System (ADS)

    Li, Jianyang; McFadden, L. A.; Thomas, P. C.; Mutchler, M.; Parker, J. W.; Young, E. F.; Russell, C. T.; Sykes, M. V.; Schmidt, B.

    2007-10-01

    We obtained 96 disk-resolved images of the target of NASA's Dawn mission, asteroid (4) Vesta, from HST's WFPC2 PC camera. The observation was planned such that complete rotational coverage over the 5.34 hr rotational period was acquired through 4 filters centered at 0.439, 0.673, 0.953, and 1.042 microns. The sub-Earth latitude at Vesta of 18-19 deg S during the observation and Earth- Vesta distance of 1.17-1.18 AU, enable mapping of the southern hemisphere at a pixel scale of 38 km/pixel. These maps will complement the previous HST mapping in 1994 (Binzel et al. 1997) that mapped more northern latitudes. The rotational lightcurve shows a single peak, consistent with the albedo dominated origin. Color variations over the four observed wavelengths are suggested by the slightly different shapes of lightcuves. Preliminary disk-resolved photometric modeling and mapping have been performed using the shape model of Vesta (Thomas et al. 1997). The albedo variation is about 10% at all filters, consistent with the light curve amplitude. The distribution of albedo is slightly bi-modal, with two peaks at about +3% and -5% of the average. We report preliminary results of the photometric analysis and mapping as well as some mineralogical interpretations from the maps.

  7. Using Colors to Improve Photometric Metallicity Estimates for Galaxies

    NASA Astrophysics Data System (ADS)

    Sanders, N. E.; Levesque, E. M.; Soderberg, A. M.

    2013-10-01

    There is a well known correlation between the mass and metallicity of star-forming galaxies. Because mass is correlated with luminosity, this relation is often exploited, when spectroscopy is not available, to estimate galaxy metallicities based on single band photometry. However, we show that galaxy color is typically more effective than luminosity as a predictor of metallicity. This is a consequence of the correlation between color and the galaxy mass-to-light ratio and the recently discovered correlation between star formation rate (SFR) and residuals from the mass-metallicity relation. Using Sloan Digital Sky Survey spectroscopy of ~180, 000 nearby galaxies, we derive "LZC relations," empirical relations between metallicity (in seven common strong line diagnostics), luminosity, and color (in 10 filter pairs and four methods of photometry). We show that these relations allow photometric metallicity estimates, based on luminosity and a single optical color, that are ~50% more precise than those made based on luminosity alone; galaxy metallicity can be estimated to within ~0.05-0.1 dex of the spectroscopically derived value depending on the diagnostic used. Including color information in photometric metallicity estimates also reduces systematic biases for populations skewed toward high or low SFR environments, as we illustrate using the host galaxy of the supernova SN 2010ay. This new tool will lend more statistical power to studies of galaxy populations, such as supernova and gamma-ray burst host environments, in ongoing and future wide-field imaging surveys.

  8. USING COLORS TO IMPROVE PHOTOMETRIC METALLICITY ESTIMATES FOR GALAXIES

    SciTech Connect

    Sanders, N. E.; Soderberg, A. M.; Levesque, E. M.

    2013-10-01

    There is a well known correlation between the mass and metallicity of star-forming galaxies. Because mass is correlated with luminosity, this relation is often exploited, when spectroscopy is not available, to estimate galaxy metallicities based on single band photometry. However, we show that galaxy color is typically more effective than luminosity as a predictor of metallicity. This is a consequence of the correlation between color and the galaxy mass-to-light ratio and the recently discovered correlation between star formation rate (SFR) and residuals from the mass-metallicity relation. Using Sloan Digital Sky Survey spectroscopy of ∼180, 000 nearby galaxies, we derive 'LZC relations', empirical relations between metallicity (in seven common strong line diagnostics), luminosity, and color (in 10 filter pairs and four methods of photometry). We show that these relations allow photometric metallicity estimates, based on luminosity and a single optical color, that are ∼50% more precise than those made based on luminosity alone; galaxy metallicity can be estimated to within ∼0.05-0.1 dex of the spectroscopically derived value depending on the diagnostic used. Including color information in photometric metallicity estimates also reduces systematic biases for populations skewed toward high or low SFR environments, as we illustrate using the host galaxy of the supernova SN 2010ay. This new tool will lend more statistical power to studies of galaxy populations, such as supernova and gamma-ray burst host environments, in ongoing and future wide-field imaging surveys.

  9. DETECTION OF KOI-13.01 USING THE PHOTOMETRIC ORBIT

    SciTech Connect

    Shporer, Avi; Jenkins, Jon M.; Seader, Shawn E.; Smith, Jeffrey C.; Thompson, Susan E.; Twicken, Joseph D.; Still, Martin D.

    2011-12-15

    We use the KOI-13 transiting star-planet system as a test case for the recently developed BEER algorithm, aimed at identifying non-transiting low-mass companions by detecting the photometric variability induced by the companion along its orbit. Such photometric variability is generated by three mechanisms: the beaming effect, tidal ellipsoidal distortion, and reflection/heating. We use data from three Kepler quarters, from the first year of the mission, while ignoring measurements within the transit and occultation, and show that the planet's ephemeris is clearly detected. We fit for the amplitude of each of the three effects and use the beaming effect amplitude to estimate the planet's minimum mass, which results in M{sub p} sin i = 9.2 {+-} 1.1 M{sub J} (assuming the host star parameters derived by Szabo et al.). Our results show that non-transiting star-planet systems similar to KOI-13.01 can be detected in Kepler data, including a measurement of the orbital ephemeris and the planet's minimum mass. Moreover, we derive a realistic estimate of the amplitudes uncertainties, and use it to show that data obtained during the entire lifetime of the Kepler mission of 3.5 years will allow detecting non-transiting close-in low-mass companions orbiting bright stars, down to the few Jupiter mass level. Data from the Kepler Extended Mission, if funded by NASA, will further improve the detection capabilities.

  10. Photometric analysis of the overcontact binary CW Cas

    SciTech Connect

    Wang, J. J.; Qian, S. B.; He, J. J.; Li, L. J.; Zhao, E. G.

    2014-11-01

    New CCD photometric observations of overcontact binary CW Cas were carried out in 2004 and 2011. In particular, the light curve obtained in 2004 shows a remarkable O'Connell effect. Compared with light curves in different observing seasons, variations were found. These variations can be explained by dark spot activities on the surface of at least one component. Using the Wilson-Devinney code with a spot model, we find that the photometric solutions confirm CW Cas is a shallow W-subtype overcontact binary with a spotted massive component. Our new determined times of minimum light together with the others published in the literature were analyzed to find a change of orbital period. From the O – C curves, the period of the system shows a cyclic period change (P {sub 3} = 69.9 yr, A {sub 3} = 0.03196 days) superposed on the linear increase. The cyclic variation, if explained as the light-travel time effect, reveals the presence of a tertiary companion.

  11. Near-infrared camera for solar research: a photometric application

    NASA Astrophysics Data System (ADS)

    Reyes, Marcos; Joven-Alvarez, Enrique; Collados, Manuel; Bonet, Jose A.; Vazquez, Manuel; Diaz, Jose J.; Fuentes, F. Javier; Escalera, Victor G.; Rodriguez, Luis F.; Garcia-Herrero, Jose L.

    1998-09-01

    We report here the main characteristics of a near IR camera devoted to astrophysical solar research, which has been developed by the Instituto de Astrofisica de Canarias (IAC). The system is now being used for photometric and spectroscopic applications, and it will also be used for spectropolarimetry in the near future. The first application is described below in detail. The IACs IR camera is based on a Rockwell 256 X 256 HgCdTe NICMOS3 array, sensitive from 1 to 2.5 microns. The necessary cooling system is a LN2- cryostat, designed and built by IR labs under out requirements. The main electronics are the standard VME- based, FPGA programmable MCE-3 system, also developed by IR labs. We have implemented different readout schemes to improve sped, reduce noise and avoid seeing effects, taking into account each specific application. Data are transferred via fiber optics to a control unit, which re-send them to the main data acquisition system. Several acquisition modes to select the best images have been implemented, and a real- time data processing is available, the entire camera has been characterized and calibrated, and the main radiometric parameters given. Preliminary test in spectroscopic observations have been made in the German Towers at the Observatorio del Teide in Tenerife, Spain, and a series of photometric measurements performed in the Swedish Solar Telescope, at the Observatorio del Roque de los Muchachos in La Palma, Spain. As examples, some scientific results are also presented.

  12. Misuse of thermodynamics in the interpretation of isothermal titration calorimetry data for ligand binding to proteins.

    PubMed

    Pethica, Brian A

    2015-03-01

    Isothermal titration calorimetry (ITC) has given a mass of data on the binding of small molecules to proteins and other biopolymers, with particular interest in drug binding to proteins chosen as therapeutic indicators. Interpretation of the enthalpy data usually follows an unsound protocol that uses thermodynamic relations in circumstances where they do not apply. Errors of interpretation include incomplete definitions of ligand binding and equilibrium constants and neglect of the non-ideality of the solutions under study, leading to unreliable estimates of standard free energies and entropies of binding. The mass of reported thermodynamic functions for ligand binding to proteins estimated from ITC enthalpies alone is consequently of uncertain thermodynamic significance and utility. ITC and related experiments to test the protocol assumptions are indicated. A thermodynamic procedure avoiding equilibrium constants or other reaction models and not requiring protein activities is given. The discussion draws attention to the fundamental but neglected relation between the thermodynamic activity and bioactivity of drugs and to the generally unknown thermodynamic status of ligand solutions, which for drugs relates directly to effective therapeutic dosimetry.

  13. Identification of a new alpha-2-macroglobulin: Multi-spectroscopic and isothermal titration calorimetry study.

    PubMed

    Rehman, Ahmed Abdur; Ahsan, Haseeb; Khan, Fahim Halim

    2016-02-01

    A α2M homologue was isolated from sheep (Ovis aries) blood plasma, using a simple two-step procedure, ammonium sulphate fractionation and gel filtration chromatography. Sheep α2M was found to be a large tetrameric glycoprotein of 630 kDa with monomeric subunit of 133 kDa each. Each subunit of sheep α2M was found to be made up of two fragments of 102 and 31 kDa respectively. The proteinase inhibitor from sheep was found to have Stokes radius of 79Ǻ, which makes it much more compact than its human homologue. It entraps only 1 mol of trypsin per mole of inhibitor, like its caprine counterpart. The use of isothermal titration calorimetry has become gold standard for exploring thermodynamics of binding interactions. In this study, binding interaction of trypsin with alpha-2-macroglobulin is studied using ITC. The thermodynamic signatures--enthalpy change (ΔH), entropy change (ΔS) and Gibb's free energy change (ΔG), along with number of binding sites (N) and affinity constant (K) are explored for α2M-trypsin binding for the first time for any known α2M molecule. The thermodynamics of proteinase-antiproteinase association suggests that trypsin-α2M interaction is enthalpy driven event.

  14. Systemic heparinization during peripheral vascular surgery: thromboelastographic, activated coagulation time, and heparin titration monitoring.

    PubMed

    Martin, P; Greenstein, D; Gupta, N K; Walker, D R; Kester, R C

    1994-04-01

    Fifteen patients (9 male, 6 female) undergoing peripheral vascular surgery were monitored during surgery for evidence of subclinical anticoagulation using the activated coagulation time (ACT), thromboelastography (TEG), and heparin titration monitoring. Assessments were made at 30-minute intervals before and after the occlusion clamp. Mean (+/- SD) ACT values preoperatively were 111 (17) seconds, and 10 minutes after 5,000 IU of heparin, the ACT was 264 (57) seconds (P < 0.001). Intraoperatively, there was a significant decline in ACT values at 30 minutes (ACT 228 [50] sec, P < 0.005) and 60 minutes (200 [46] sec, P < 0.001) postheparin. No significant difference in ACT was observed between samples drawn distally and proximally to the clamp. TEG profiles were abolished in all patients immediately following heparinization. However, in 2 patients nearly complete return of the TEG coagulation profile was observed prior to the termination of the procedure and was associated with ACT values less than 160 seconds. The heparin device was unable to accurately monitor heparin elimination at these low doses. Variability of patient response to heparinization necessitates the use of intraoperative monitoring of anticoagulation during peripheral vascular surgery.

  15. [Determination of total protein content in soya-bean milk via visual moving reaction boundary titration].

    PubMed

    Guo, Chengye; Wang, Houyu; Zhang, Lei; Fan, Liuyin; Cao, Chengxi

    2013-11-01

    A visual, rapid and accurate moving reaction boundary titration (MRBT) method was used for the determination of the total protein in soya-bean milk. During the process, moving reaction boundary (MRB) was formed by hydroxyl ions in the catholyte and soya-bean milk proteins immobilized in polyacrylamide gel (PAG), and an acid-base indicator was used to denote the boundary motion. The velocity of MRB has a relationship with protein concentration, which was used to obtain a standard curve. By paired t-test, there was no significant difference of the protein content between MRBT and Kjeldahl method at 95% confidence interval. The procedure of MRBT method required about 10 min, and it had linearity in the range of 2.0-14.0 g/L, low limit of detection (0.05 g/L), good precision (RSD of intra-day < 1.90% and inter-day < 4.39%), and high recoveries (97.41%-99.91%). In addition, non-protein nitrogen (NPN) such as melamine added into the soya-bean milk had weak influence on MRBT results.

  16. Titration-free 454 sequencing using Y adapters.

    PubMed

    Zheng, Zongli; Advani, Abdolreza; Melefors, Öjar; Glavas, Steve; Nordström, Henrik; Ye, Weimin; Engstrand, Lars; Andersson, Anders F

    2011-09-01

    We describe a protocol for construction and quantification of libraries for emulsion PCR (emPCR)-based sequencing platforms such as Roche 454 or Ion Torrent PGM. The protocol involves library construction using customized Y adapters, quantification using TaqMan-MGB (minor groove binder) probe-based quantitative PCR (qPCR) and calculation of an optimal template-to-bead ratio based on Poisson statistics, thereby avoiding the need for a laborious titration assay. Unlike other qPCR methods, the TaqMan-MGB probe specifically quantifies effective libraries in molar concentration and does not require specialized equipment. A single quality control step prior to emulsion PCR ensures that libraries contain no adapter dimers and have an optimal length distribution. The presented protocol takes ∼7 h to prepare eight barcoded libraries from genomic DNA into libraries that are ready to use for full-scale emPCR. It will be useful, for example, to allow analyses of precious clinical samples and amplification-free metatranscriptomics.

  17. Evaluation of different calculation methods for anti-HBs titration.

    PubMed

    Vranckx, R P

    1989-11-01

    Anti-HBs titre calculations should be standardized to make comparison between various vaccination programmes and between immunogenicity tests in animals more meaningful. For this purpose, we compared four methods of titre calculation in human and animal sera and in the IgM and IgG fractions of these sera. The four calculation methods are parallel line bioassay, Hollinger method, RIA units and regression-calibration curve. From our results, the following can be concluded: The titration curves of anti-HBs/IgM, anti-HBs/IgG and of animal sera do not always run parallel to the WHO standard curve. Thus, the objective quantification of these anti-HBs cannot be obtained with the WHO standard. The Hollinger method and the RIA units method are identical within the range S/P less than 1. They only differ by a factor of 4. Only dilutions giving results in the linear part of the dose-response curve should be considered for titre calculations. The mean of the results for different dilutions should be used to determine the titre. Within the restrictions mentioned, comparable results were obtained with the four methods.

  18. Characterization of membrane protein interactions by isothermal titration calorimetry.

    PubMed

    Situ, Alan J; Schmidt, Thomas; Mazumder, Parichita; Ulmer, Tobias S

    2014-10-23

    Understanding the structure, folding, and interaction of membrane proteins requires experimental tools to quantify the association of transmembrane (TM) helices. Here, we introduce isothermal titration calorimetry (ITC) to measure integrin αIIbβ3 TM complex affinity, to study the consequences of helix-helix preorientation in lipid bilayers, and to examine protein-induced lipid reorganization. Phospholipid bicelles served as membrane mimics. The association of αIIbβ3 proceeded with a free energy change of -4.61±0.04kcal/mol at bicelle conditions where the sampling of random helix-helix orientations leads to complex formation. At bicelle conditions that approach a true bilayer structure in effect, an entropy saving of >1kcal/mol was obtained from helix-helix preorientation. The magnitudes of enthalpy and entropy changes increased distinctly with bicelle dimensions, indicating long-range changes in bicelle lipid properties upon αIIbβ3 TM association. NMR spectroscopy confirmed ITC affinity measurements and revealed αIIbβ3 association and dissociation rates of 4500±100s(-1) and 2.1±0.1s(-1), respectively. Thus, ITC is able to provide comprehensive insight into the interaction of membrane proteins.

  19. Predicting proton titration in cationic micelle and bilayer environments

    SciTech Connect

    Morrow, Brian H.; Shen, Jana K.; Eike, David M.; Murch, Bruce P.; Koenig, Peter H.

    2014-08-28

    Knowledge of the protonation behavior of pH-sensitive molecules in micelles and bilayers has significant implications in consumer product development and biomedical applications. However, the calculation of pK{sub a}’s in such environments proves challenging using traditional structure-based calculations. Here we apply all-atom constant pH molecular dynamics with explicit ions and titratable water to calculate the pK{sub a} of a fatty acid molecule in a micelle of dodecyl trimethylammonium chloride and liquid as well as gel-phase bilayers of diethyl ester dimethylammonium chloride. Interestingly, the pK{sub a} of the fatty acid in the gel bilayer is 5.4, 0.4 units lower than that in the analogous liquid bilayer or micelle, despite the fact that the protonated carboxylic group is significantly more desolvated in the gel bilayer. This work illustrates the capability of all-atom constant pH molecular dynamics in capturing the delicate balance in the free energies of desolvation and Coulombic interactions. It also shows the importance of the explicit treatment of ions in sampling the protonation states. The ability to model dynamics of pH-responsive substrates in a bilayer environment is useful for improving fabric care products as well as our understanding of the side effects of anti-inflammatory drugs.

  20. Predicting proton titration in cationic micelle and bilayer environments

    NASA Astrophysics Data System (ADS)

    Morrow, Brian H.; Eike, David M.; Murch, Bruce P.; Koenig, Peter H.; Shen, Jana K.

    2014-08-01

    Knowledge of the protonation behavior of pH-sensitive molecules in micelles and bilayers has significant implications in consumer product development and biomedical applications. However, the calculation of pKa's in such environments proves challenging using traditional structure-based calculations. Here we apply all-atom constant pH molecular dynamics with explicit ions and titratable water to calculate the pKa of a fatty acid molecule in a micelle of dodecyl trimethylammonium chloride and liquid as well as gel-phase bilayers of diethyl ester dimethylammonium chloride. Interestingly, the pKa of the fatty acid in the gel bilayer is 5.4, 0.4 units lower than that in the analogous liquid bilayer or micelle, despite the fact that the protonated carboxylic group is significantly more desolvated in the gel bilayer. This work illustrates the capability of all-atom constant pH molecular dynamics in capturing the delicate balance in the free energies of desolvation and Coulombic interactions. It also shows the importance of the explicit treatment of ions in sampling the protonation states. The ability to model dynamics of pH-responsive substrates in a bilayer environment is useful for improving fabric care products as well as our understanding of the side effects of anti-inflammatory drugs.

  1. Predicting proton titration in cationic micelle and bilayer environments

    PubMed Central

    Morrow, Brian H.; Eike, David M.; Murch, Bruce P.; Koenig, Peter H.; Shen, Jana K.

    2014-01-01

    Knowledge of the protonation behavior of pH-sensitive molecules in micelles and bilayers has significant implications in consumer product development and biomedical applications. However, the calculation of pKa’s in such environments proves challenging using traditional structure-based calculations. Here we apply all-atom constant pH molecular dynamics with explicit ions and titratable water to calculate the pKa of a fatty acid molecule in a micelle of dodecyl trimethylammonium chloride and liquid as well as gel-phase bilayers of diethyl ester dimethylammonium chloride. Interestingly, the pKa of the fatty acid in the gel bilayer is 5.4, 0.4 units lower than that in the analogous liquid bilayer or micelle, despite the fact that the protonated carboxylic group is significantly more desolvated in the gel bilayer. This work illustrates the capability of all-atom constant pH molecular dynamics in capturing the delicate balance in the free energies of desolvation and Coulombic interactions. It also shows the importance of the explicit treatment of ions in sampling the protonation states. The ability to model dynamics of pH-responsive substrates in a bilayer environment is useful for improving fabric care products as well as our understanding of the side effects of anti-inflammatory drugs. PMID:25173037

  2. Enzyme kinetics determined by single-injection isothermal titration calorimetry.

    PubMed

    Transtrum, Mark K; Hansen, Lee D; Quinn, Colette

    2015-04-01

    The purposes of this paper are (a) to examine the effect of calorimeter time constant (τ) on heat rate data from a single enzyme injection into substrate in an isothermal titration calorimeter (ITC), (b) to provide information that can be used to predict the optimum experimental conditions for determining the rate constant (k2), Michaelis constant (KM), and enthalpy change of the reaction (ΔRH), and (c) to describe methods for evaluating these parameters. We find that KM, k2 and ΔRH can be accurately estimated without correcting for the calorimeter time constant, τ, if (k2E/KM), where E is the total active enzyme concentration, is between 0.1/τ and 1/τ and the reaction goes to at least 99% completion. If experimental conditions are outside this domain and no correction is made for τ, errors in the inferred parameters quickly become unreasonable. A method for fitting single-injection data to the Michaelis-Menten or Briggs-Haldane model to simultaneously evaluate KM, k2, ΔRH, and τ is described and validated with experimental data. All four of these parameters can be accurately inferred provided the reaction time constant (k2E/KM) is larger than 1/τ and the data include enzyme saturated conditions.

  3. Mapping glycoside hydrolase substrate subsites by isothermal titration calorimetry

    PubMed Central

    Zolotnitsky, Gennady; Cogan, Uri; Adir, Noam; Solomon, Vered; Shoham, Gil; Shoham, Yuval

    2004-01-01

    Relating thermodynamic parameters to structural and biochemical data allows a better understanding of substrate binding and its contribution to catalysis. The analysis of the binding of carbohydrates to proteins or enzymes is a special challenge because of the multiple interactions and forces involved. Isothermal titration calorimetry (ITC) provides a direct measure of binding enthalpy (ΔHa) and allows the determination of the binding constant (free energy), entropy, and stoichiometry. In this study, we used ITC to elucidate the binding thermodynamics of xylosaccharides for two xylanases of family 10 isolated from Geobacillus stearothermophilus T-6. The change in the heat capacity of binding (ΔCp = ΔH/ΔT) for xylosaccharides differing in one sugar unit was determined by using ITC measurements at different temperatures. Because hydrophobic stacking interactions are associated with negative ΔCp, the data allow us to predict the substrate binding preference in the binding subsites based on the crystal structure of the enzyme. The proposed positional binding preference was consistent with mutants lacking aromatic binding residues at different subsites and was also supported by tryptophan fluorescence analysis. PMID:15277671

  4. Behaviour of ferroin indicator in iron(ii)- dichromate titrations A Critical study.

    PubMed

    Sriramam, K

    1972-10-01

    A critical evaluation has been made of the optimum conditions for a successful direct and reverse titration of iron(II) with dichromate, with ferroin as indicator, taking into account the influence of acidity, the catalytic effect of iron(III) and the induction effect of the iron(II)-dichromate reaction on the indicator oxidation reaction. The difference in the behaviour of the indicator in the direct and reverse titrations is believed to be due to the presence of a slow : step in the indicator oxidation mechanism ; this is however surmounted in the reverse titration, making it possible to use the indicator even in a 2N sulphuric add medium for this titration. The higher potentials recorded in the reverse titration are believed to be due to the oxide film on the platinum metal electrode. While iron(III) seems to help lower the kinetic barrier of the slow step sufficiently in the indicator oxidation mechanism, the ferriin-ferroin system seems to help m a similar way toe establishment of a more positive potential of the Ct(VI)/Cr(III) system at the platinum electrode in me direct titration; this value explains the feasibility of the direct visual titration in 2N sulphuric acid, although the colour change at the end-point is slow for other reasons.

  5. Polarographic indication of the end-point in chelometric titrations with triethylenetetraminehexa-acetic acid.

    PubMed

    Kopanica, M; Stará, V

    1974-10-01

    The application of d.c. and square-wave polarographic measurements for the indication of the end-point in titrations with triethylenetetraminehexa-acetic acid (TTHA) has been studied. TTHA has ten co-ordinating groups and forms complexes with metal to ligand ratios of either 1:1 or 2:1, depending on the metal and experimental conditions. The shape of the titration curves, determined by the dependence of the limiting current (peak current of the square-wave polarographic curve) or of the half-wave potential (peak potential) on the amount of TTHA added indicates the composition of the complex formed in the titration. The composition of this complex as determined from the studied titration curves agrees with that predicted by theory. Titrations with polarographic indication of the end-point were also applied for direct titrations of binary mixtures of metal ions. The resulting titration curves indicated the existence of mixed dinuclear complexes and also the kinetic factors involved in the reactions between two different metal ions and TTHA.

  6. Rapid baculovirus titration based on regulatable green fluorescent protein expression in mammalian cells.

    PubMed

    Lo, Wen-Hsin; Chen, Chi-Yuan; Yeh, Chia-Ni; Lin, Chin-Yu; Hu, Yu-Chen

    2011-01-01

    Baculovirus is a promising gene delivery vector and can be titrated by constitutive EGFP expression in HeLa cells, which, however, might interfere with target transgene expression and impart cytotoxicity. Here we constructed Bac-ME accommodating egfp under the inducible metallothionein promoter and Bac-MECB harboring an additional BMP-2 gene. Bac-ME effectively transduced HeLa cells with minimal leaky expression, but expressed EGFP robustly upon induction with ZnSO(4), hence allowing for virus titration by transducing HeLa cells with serially diluted virus, subsequent ZnSO(4) induction and flow cytometry analysis of EGFP-positive cells. The titration protocol enabled the generation of discernable titration curves, determination of transducing titers, and discrimination of the transducing abilities of different virus batches. After titration, cell transduction with pre-determined Bac-ME dose revealed consistent transduction efficiency dependence on the dose, regardless of virus batch and cell type. Bac-MECB was similarly titrated by inducible EGFP expression and used to transduce de-differentiated articular chondrocytes without EGFP induction. BMP-2 expression was proportional to the Bac-MECB dose and promoted cartilage-specific matrix synthesis, implicating the potential of Bac-MECB in restoring chondrocyte differentiation. These data confirmed that regulatable EGFP expression enabled rapid, reliable baculovirus titration without interference with subsequent applications.

  7. Assessing Coupled Protein Folding and Binding Through Temperature-Dependent Isothermal Titration Calorimetry.

    PubMed

    Sahu, Debashish; Bastidas, Monique; Lawrence, Chad W; Noid, William G; Showalter, Scott A

    2016-01-01

    Broad interest in the thermodynamic driving forces of coupled macromolecular folding and binding is motivated by the prevalence of disorder-to-order transitions observed when intrinsically disordered proteins (IDPs) bind to their partners. Isothermal titration calorimetry (ITC) is one of the few methods available for completely evaluating the thermodynamic parameters describing a protein-ligand binding event. Significantly, when the effective ΔH° for the coupled folding and binding process is determined by ITC in a temperature series, the constant-pressure heat capacity change (ΔCp) associated with these coupled equilibria is experimentally accessible, offering a unique opportunity to investigate the driving forces behind them. Notably, each of these molecular-scale events is often accompanied by strongly temperature-dependent enthalpy changes, even over the narrow temperature range experimentally accessible for biomolecules, making single temperature determinations of ΔH° less informative than typically assumed. Here, we will document the procedures we have adopted in our laboratory for designing, executing, and globally analyzing temperature-dependent ITC studies of coupled folding and binding in IDP interactions. As a biologically significant example, our recent evaluation of temperature-dependent interactions between the disordered tail of FCP1 and the winged-helix domain from Rap74 will be presented. Emphasis will be placed on the use of publically available analysis programs written in MATLAB that facilitate quantification of the thermodynamic forces governing IDP interactions. Although motivated from the perspective of IDPs, the experimental design principles and data fitting procedures presented here are general to the study of most noncooperative ligand binding equilibria.

  8. Assessing Coupled Protein Folding and Binding Through Temperature-Dependent Isothermal Titration Calorimetry.

    PubMed

    Sahu, Debashish; Bastidas, Monique; Lawrence, Chad W; Noid, William G; Showalter, Scott A

    2016-01-01

    Broad interest in the thermodynamic driving forces of coupled macromolecular folding and binding is motivated by the prevalence of disorder-to-order transitions observed when intrinsically disordered proteins (IDPs) bind to their partners. Isothermal titration calorimetry (ITC) is one of the few methods available for completely evaluating the thermodynamic parameters describing a protein-ligand binding event. Significantly, when the effective ΔH° for the coupled folding and binding process is determined by ITC in a temperature series, the constant-pressure heat capacity change (ΔCp) associated with these coupled equilibria is experimentally accessible, offering a unique opportunity to investigate the driving forces behind them. Notably, each of these molecular-scale events is often accompanied by strongly temperature-dependent enthalpy changes, even over the narrow temperature range experimentally accessible for biomolecules, making single temperature determinations of ΔH° less informative than typically assumed. Here, we will document the procedures we have adopted in our laboratory for designing, executing, and globally analyzing temperature-dependent ITC studies of coupled folding and binding in IDP interactions. As a biologically significant example, our recent evaluation of temperature-dependent interactions between the disordered tail of FCP1 and the winged-helix domain from Rap74 will be presented. Emphasis will be placed on the use of publically available analysis programs written in MATLAB that facilitate quantification of the thermodynamic forces governing IDP interactions. Although motivated from the perspective of IDPs, the experimental design principles and data fitting procedures presented here are general to the study of most noncooperative ligand binding equilibria. PMID:26794349

  9. Photometric Properties of the Most Massive High-Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Robertson, Brant; Li, Yuexing; Cox, Thomas J.; Hernquist, Lars; Hopkins, Philip F.

    2007-09-01

    We calculate the observable properties of the most massive high-redshift galaxies in the hierarchical formation scenario where stellar spheroid and supermassive black hole growth are fueled by gas-rich mergers. Combining high-resolution hydrodynamical simulations of the hierarchical formation of a z~6 quasar, stellar population synthesis models, template active galactic nucleus (AGN) spectra, prescriptions for interstellar and intergalactic absorption, and the response of modern telescopes, the photometric evolution of galaxies destined to host z~6 quasars is modeled at redshifts z~4-14. These massive galaxies, with enormous stellar masses of M*~1011.5-1012 Msolar and star formation rates of SFR~103-104 Msolar yr-1 at z>~7, satisfy a variety of photometric selection criteria based on Lyman break techniques, including V-band dropouts at z>~5, i-band dropouts at z>~6, and z-band dropouts at z>~7. The observability of the most massive high-redshift galaxies is assessed and compared with a wide range of existing and proposed photometric surveys, including the Sloan Digital Sky Survey (SDSS), Great Observatories Origins Deep Survey (GOODS)/Hubble Ultra Deep Field (HUDF), National Optical Astronomy Observatory Deep Wide-Field Survey (NDWFS), UKIRT Infared Deep Sky Survey (UKIDSS), Infrared Array Camera (IRAC) Shallow Survey, Ultradeep Visible and Infrared Survey Telescope for Astronomy (VISTA), Dark Universe Explorer (DUNE), Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), Large Synoptic Survey Telescope (LSST), and Supernova/Acceleration Probe (SNAP). Massive stellar spheroids descended from z~6 quasars will likely be detected at z~4 by existing surveys, but owing to their low number densities the discovery of quasar progenitor galaxies at z>7 will likely require future surveys of large portions of the sky (>~0.5%) at wavelengths λ>~1 μm. The detection of rare, starbursting, massive galaxies at redshifts z>~6 would provide support for the

  10. Photometric modeling of viscous overstability in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Salo, H.; Schmidt, J.

    2011-10-01

    The viscous overstability of dense planetary rings offers a plausible mechanism for the generation of observed ~ 150 m radial density variations in the B and the inner A ring of Saturn [1, 12]. Viscous overstability, in the form of spontaneous growth of axisymmetric oscillations, arises naturally in N-body simulations, in the limit of high impact frequency and moderately weak selfgravity [4, 8, 9, 10]. For example, a selfgravitating system of identical particles with internal density ~ half of solid ice, becomes overstable for optical depths τ > 1, forming oscillations on about 100 meter scale. Like self-gravity wakes (with typical ~ 20° trailing pitch angle), overstable oscillations lead to alongitude-dependent brightness of the rings. Due to their axisymmetric nature, the expected longitude of minimum brightness is shifted closer to ring ansae (for small phase angles). Moreover, according to simulations, the axisymmetric oscillations may coexist with the inclined selfgravity wake structures, which can lead to complicated photometric behavior as a function of illumination and viewing geometries, depending on properties of the simulated system. For example, at low viewing elevations, the vertical thickenings associated with the density crests should cast shadows on the nearby ring particles (see Fig. 1 for an example; darker areas are due to shadows, not due to depletion of particles). Though these shadows would be unresolved, they might still affect the integrated brightness at certain geometries. The overstable systems may also exhibit amplitude variations (in km-scales), arising from the mutual beating patterns of the basic sub-km overstable oscillations [3]. Such modulations of oscillation amplitude may lead to associated brightness variations. New results of photometric modeling of viscously overstable dynamical simulations systems are reported, related to the above mentioned topics. The Monte Carlo method of [5] is used, previously applied to modeling of

  11. J-PLUS: The Javalambre Photometric Local Universe Survey

    NASA Astrophysics Data System (ADS)

    Cenarro, Javier; Marin-Franch, Antonio; Moles, Mariano; Cristobal-Hornillos, David; Mendes de Oliveira, Claudia; Sodre, Laerte

    2015-08-01

    The Javalambre-Photometric Local Universe Survey, J-PLUS (www.j-plus.es), is defined to observe 8500 deg2 of the sky visible from the Javalambre Observatory (Teruel, Spain) with the panoramic camera T80Cam at the JAST/T80 telescope, using a set of 12 broad, intermediate and narrow band optical filters. The Project is particularly designed to carry out the photometric calibration of J-PAS (http://j-pas.org). For this reason, some J-PLUS filters are located at key stellar spectral features that allow to retrieve very accurate spectral energy distributions for more than 5 millions of stars in our Galaxy. Beyond the calibration goals, the unusually large FOV of T80Cam, 2deg2, together with the unique width and location of some filters, turn the J-PLUS Project into a powerful 3D view of the nearby Universe, mapping more than 20 millions of galaxies with reliable distance determinations and a similar number of stars of the Milky Way halo. At a rate of 100 gigabytes of data per night, J-PLUS will provide unprecedented multi-color images of the Universe to address a wide variety of astrophysical questions related with cosmology, large scale structure, galaxy clusters, 2D stellar populations and star formation studies in galaxies, the discovery of high redshift galaxies at specific redshift slices, quasars, supernovae, Milky Way science and structure, and minor bodies in the Solar System. In addition, the repetition of the whole area over time in certain filters will allow to face variability studies in the time domain.Complementing J-PLUS, a replica of the JAST/T80 telescope, T80Cam and the J-PLUS filters have been installed at the CTIO, allowing to extend the project to the Southern Hemisphere. J-PLUS together with the southern extension, S-PLUS, constitute an All-sky Photometric Local Universe Survey whose details and scientific applications are the bulk of the present talk.

  12. Dynamic and photometric evolutionary models of tidal tails and ripples

    NASA Astrophysics Data System (ADS)

    Wallin, John F.

    The causes of star formation in tidal tails were investigated using a restricted three-body dynamical model in conjunction with a broad-band photometric evolutionary code. In these models, regions of compression form inside the disk and along the tidal tail and tidal bridge. The effects these density changes have on the colors of the tidal features are examined with a broad-band photometric evolutionary code. A spiral galaxy population is synthesized and the effects of modest changes in the star formation rate are explored. Limits on the density changes needed to make detectable changes in the colors are calculated using a Schmidt (1959) law. These models suggest that the blue colors and knotty features observed in the tidal features of some galaxies result from increased rates of star formation induced by tidally produced density increases. Limitations of this model are discussed along with photometric evolutionary models based on the density evolution in the tails. The Lynds and Toomre (1976) interpretation of ring galaxies as the natural result of a nearly head-on collision between a disk galaxy and a companion galaxy has become widely accepted. Similarly, Quinn's (1984) interpretation of the shells in elliptical galaxies as the aftermath of the cannibalization of a low-mass companion was quite successful in accounting for the observations. Restricted three-body calculations of high inclination, low impact parameter encounters demonstrate that the shell-like ripples observed in a number of disk galaxies (cf. Schweizer and Seitzer 1988) can also be produced as collisional artifacts from internal oscillations much as in ring galaxies. However, in this case it is assumed that the target is an early-type disk with a sufficiently low gas fraction that recent star formation does not dominate the appearance of the disturbed disk. It should be emphasized that the models presented here are in a transient stage of an evolutionary sequence, whose outcome is most probably

  13. Photometric classification of quasars from RCS-2 using Random Forest

    NASA Astrophysics Data System (ADS)

    Carrasco, D.; Barrientos, L. F.; Pichara, K.; Anguita, T.; Murphy, D. N. A.; Gilbank, D. G.; Gladders, M. D.; Yee, H. K. C.; Hsieh, B. C.; López, S.

    2015-12-01

    The classification and identification of quasars is fundamental to many astronomical research areas. Given the large volume of photometric survey data available in the near future, automated methods for doing so are required. In this article, we present a new quasar candidate catalog from the Red-Sequence Cluster Survey 2 (RCS-2), identified solely from photometric information using an automated algorithm suitable for large surveys. The algorithm performance is tested using a well-defined SDSS spectroscopic sample of quasars and stars. The Random Forest algorithm constructs the catalog from RCS-2 point sources using SDSS spectroscopically-confirmed stars and quasars. The algorithm identifies putative quasars from broadband magnitudes (g, r, i, z) and colors. Exploiting NUV GALEX measurements for a subset of the objects, we refine the classifier by adding new information. An additional subset of the data with WISE W1 and W2 bands is also studied. Upon analyzing 542 897 RCS-2 point sources, the algorithm identified 21 501 quasar candidates with a training-set-derived precision (the fraction of true positives within the group assigned quasar status) of 89.5% and recall (the fraction of true positives relative to all sources that actually are quasars) of 88.4%. These performance metrics improve for the GALEX subset: 6529 quasar candidates are identified from 16 898 sources, with a precision and recall of 97.0% and 97.5%, respectively. Algorithm performance is further improved when WISE data are included, with precision and recall increasing to 99.3% and 99.1%, respectively, for 21 834 quasar candidates from 242 902 sources. We compiled our final catalog (38 257) by merging these samples and removing duplicates. An observational follow up of 17 bright (r < 19) candidates with long-slit spectroscopy at DuPont telescope (LCO) yields 14 confirmed quasars. The results signal encouraging progress in the classification of point sources with Random Forest algorithms to search

  14. Titration of intravenous synthetic oxytocin post vaginal birth following induction or augmentation.

    PubMed

    Lewis, Lucy; Hauck, Yvonne L; Pemberton, Alissa; Crichton, Caroline; Conwell, Marion

    2016-10-01

    Evidence exists for titration of intravenous oxytocin during induction and augmentation, whereas no evidence was identified for titration of intravenous oxytocin following vaginal birth, where management excluded oxytocin for postpartum haemorrhage (PPH). This retrospective cohort study explored this issue through patient case notes and computerised perinatal data. Analysis included 335 women comparing induction (n = 226, 67%) to augmentation (n = 109, 33%). The two groups differed in terms of: parity; oxytocin dosage; length of time on intravenous oxytocin; and the length of first and second stage labour. They had similar rates of PPH and titration of intravenous oxytocin following birth was rarely recorded.

  15. Comparison of methods for accurate end-point detection of potentiometric titrations

    NASA Astrophysics Data System (ADS)

    Villela, R. L. A.; Borges, P. P.; Vyskočil, L.

    2015-01-01

    Detection of the end point in potentiometric titrations has wide application on experiments that demand very low measurement uncertainties mainly for certifying reference materials. Simulations of experimental coulometric titration data and consequential error analysis of the end-point values were conducted using a programming code. These simulations revealed that the Levenberg-Marquardt method is in general more accurate than the traditional second derivative technique used currently as end-point detection for potentiometric titrations. Performance of the methods will be compared and presented in this paper.

  16. Quantitative real-time PCR for rapid and accurate titration of recombinant baculovirus particles.

    PubMed

    Hitchman, Richard B; Siaterli, Evangelia A; Nixon, Clare P; King, Linda A

    2007-03-01

    We describe the use of quantitative PCR (QPCR) to titer recombinant baculoviruses. Custom primers and probe were designed to gp64 and used to calculate a standard curve of QPCR derived titers from dilutions of a previously titrated baculovirus stock. Each dilution was titrated by both plaque assay and QPCR, producing a consistent and reproducible inverse relationship between C(T) and plaque forming units per milliliter. No significant difference was observed between titers produced by QPCR and plaque assay for 12 recombinant viruses, confirming the validity of this technique as a rapid and accurate method of baculovirus titration.

  17. A numerical method of finding potentiometric titration end-points by use of approximative spline functions.

    PubMed

    Ren, K

    1990-07-01

    A new numerical method of determining potentiometric titration end-points is presented. It consists in calculating the coefficients of approximative spline functions describing the experimental data (e.m.f., volume of titrant added). The end-point (the inflection point of the curve) is determined by calculating zero points of the second derivative of the approximative spline function. This spline function, unlike rational spline functions, is free from oscillations and its course is largely independent of random errors in e.m.f. measurements. The proposed method is useful for direct analysis of titration data and especially as a basis for construction of microcomputer-controlled automatic titrators. PMID:18964999

  18. On the Physical Meaning of the Isothermal Titration Calorimetry Measurements in Calorimeters with Full Cells

    PubMed Central

    Grolier, Jean-Pierre E.; del Río, Jose Manuel

    2009-01-01

    We have performed a detailed study of the thermodynamics of the titration process in an isothermal titration calorimeter with full cells. We show that the relationship between the enthalpy and the heat measured is better described in terms of the equation Δ H = Winj + Q (where Winj is the work necessary to carry out the titration) than in terms of ΔH = Q. Moreover, we show that the heat of interaction between two components is related to the partial enthalpy of interaction at infinite dilution of the titrant component, as well as to its partial volume of interaction at infinite dilution. PMID:20054472

  19. Titration of intravenous synthetic oxytocin post vaginal birth following induction or augmentation.

    PubMed

    Lewis, Lucy; Hauck, Yvonne L; Pemberton, Alissa; Crichton, Caroline; Conwell, Marion

    2016-10-01

    Evidence exists for titration of intravenous oxytocin during induction and augmentation, whereas no evidence was identified for titration of intravenous oxytocin following vaginal birth, where management excluded oxytocin for postpartum haemorrhage (PPH). This retrospective cohort study explored this issue through patient case notes and computerised perinatal data. Analysis included 335 women comparing induction (n = 226, 67%) to augmentation (n = 109, 33%). The two groups differed in terms of: parity; oxytocin dosage; length of time on intravenous oxytocin; and the length of first and second stage labour. They had similar rates of PPH and titration of intravenous oxytocin following birth was rarely recorded. PMID:27634662

  20. 2-methoxyethanol as a solvent for conductometric acid-base titrations.

    PubMed

    Schwartz, G A; Barker, B J

    1975-09-01

    Conductometric titrations of a series of organic acids in 2-methoxyethanol were performed with 1,3-diphenylguanidine (DPG) as titrant. For benzoic, p-chlorobenzoic and picric acids, phenylphenol and barbital, excellent recoveries were obtained from well-defined conductance vs. volume plots. Results for the dicarboxylic phthalic and adipic acids were also good. However, the titration curves for the difunctional salicylic and p-hydroxybenzoic acids were not clearly defined. The results are discussed and compared with cnductometric titrations of acids in other non-aqueous solvents. Several determinations of electrolyte conductance as a function of concentration revealed that, as expected, the selected substances are weak electrolytes in methoxyethanol.

  1. Photometric Follow-Up of A Likely Galactic Nova ASASSN-16kt: Almost Naked Eye

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Dong, Subo; Bose, S.; Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Holoien, T. W.-S.; Shields, J.; Shappee, B. J.; Prieto, J. L.; Bersier, D.; Chomiuk, L.; Strader, J.; Brimacombe, J.

    2016-09-01

    We obtained follow-up photometric observations of ASASSN-16kt (ATel #9538 & ATel #9539) with LCOGT 1m telescope at Sutherland, South Africa (SAAO). We performed aperture photometry on the images using the IRAF apphot package and calibrated the results using the AAVSO Photometric All-Sky Survey (APASS; Henden et al. 2015).

  2. On specific features of investigation of fluid flows by photometric techniques

    NASA Astrophysics Data System (ADS)

    Vologdin, V. A.; Davydov, V. V.; Velichko, E. N.

    2016-08-01

    Specific features of investigation of the fluid flow structure in a pipeline by photometric techniques are considered. The applicability of the photometric techniques based on the Doppler effect to such studies is discussed. A new method for detecting defects on inner walls of a pipeline that involves the use of the laser radiation scattered from particles in a flowing fluid is suggested.

  3. 21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Discrete photometric chemistry analyzer for... AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Laboratory Instruments § 862.2160 Discrete photometric chemistry analyzer for clinical use....

  4. 21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Discrete photometric chemistry analyzer for... AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Laboratory Instruments § 862.2160 Discrete photometric chemistry analyzer for clinical use....

  5. Etalon-photometric method for estimation of tissues density at x-ray images

    NASA Astrophysics Data System (ADS)

    Buldakov, Nicolay S.; Buldakova, Tatyana I.; Suyatinov, Sergey I.

    2016-04-01

    The etalon-photometric method for quantitative estimation of physical density of pathological entities is considered. The method consists in using etalon during the registration and estimation of photometric characteristics of objects. The algorithm for estimating of physical density at X-ray images is offered.

  6. Sensitivity of Aedes albopictus C6/36 cells line for the detection and infectivity titration of dengue virus.

    PubMed

    Zamree, I; Drakes, N; Rohani, A; Lee, H L

    2005-12-01

    Plaque assay procedure was carried out to determine the infectivity titration of dengue virus using Aedes albopictus C6/36 mosquito cell line. Cells were seeded in 6 wells plates and incubated until monolayer C6/36 cell lines were formed. Each well was exposed to a different dilution of dengue infected culture fluid, followed by addition of first and second overlay medium. Cells were observed under an inverted microscope and plaque staining was carried out. The results showed that countable plaques were not achieved and plaques formed were restricted to the central section due to the significant partial lysis of the C6/36 cells in the plates. However, the plaque assay technique using C6/36 cell line reported here appears to be promising and merits further detailed studies.

  7. Fifth image and photometric variability in 2237 + 0305 ('Einstein Cross')

    SciTech Connect

    Racine, R. Montreal, Universite, Montreal Canada-France-Hawaii Telescope Corp., Kamuela, HI )

    1991-08-01

    The paper describes the morphological and photometric characteristics of the gravitational mirage 2237 + 0305, obtained by combining CCD frames in R and I taken with HRCam at the CFHT in a 0.4 arcsec (FWHM) observation on August 23, 1990. High S/N images of the 2237 + 0305 provided precise positions and relative magnitudes for the four brighter components and for the galaxy core, and new information on the light distribution in the lensing galaxy core was obtained. Compared with Yee's (1988) photometry, the present data show components B brighter by 0.25 mag and C fainter by 0.15 mag, while the brightness of A and D and the colors of all four images are unchanged. Possible reason for the variability trends of the four components are discussed. 19 refs.

  8. A photometrically and spectroscopically confirmed population of passive spiral galaxies

    NASA Astrophysics Data System (ADS)

    Fraser-McKelvie, Amelia; Brown, Michael J. I.; Pimbblet, Kevin A.; Dolley, Tim; Crossett, Jacob P.; Bonne, Nicolas J.

    2016-10-01

    We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z < 0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption-line spectra with 4000 Å breaks consistent with an average luminosity-weighted age of 2.3 Gyr. Our photometric and integral field spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.

  9. Simultaneous Hα and photometric observations of P Cygni

    NASA Astrophysics Data System (ADS)

    Markova, N.; Scuderi, S.; de Groot, M.; Markov, H.; Panagia, N.

    2001-02-01

    For the first time an extensive set of (quasi-) simultaneous photometric (UBV) and spectroscopic (Hα line profiles) observations of P Cygni, covering a period from May, 1990 to June, 1994 was analyzed in terms of time variability. It is found that the Hα equivalent width (EW) exhibits two different patterns of variability: a slower one, called Long-Term (LT) variability, with an amplitude of about 30 Åand a characteristic duration of about 600 days and a faster one, called Short-Term (ST) variability, with an amplitude up to 10 Åand duration of 40 to 60 days. Suggestive evidence for EW variation on a longer time scale (about few years) also exists. The variations in the Hα luminosity are not solely due to changes in the underlying continuum but also reflect variations in the physical properties of the wind. We find, in terms of a simplified spherically-symmetric wind model, that the LT variation of the line can be successfully explained in terms of a 26% alteration of the mass-loss rate, possibly accompanied by variations in the velocity field. From the analysis of the photometric behaviour of the star we find evidence for a very slow variation in the stellar brightness with an amplitude of about 0.13 mag and a duration of about 2600 days, i.e. about 7 years. During this variation, i.e. when the star brightens, the effective temperature decreases (by about 10%) and the radius increases (by about 7%). The properties of this Very Long Term (VLT) variation suggest that P Cygni has probably experienced a normal S Dor-type variation with a minimum phase around 1988 and a maximum phase in 1992. Some hints for a positive correlation between mass loss variations and changes in the stellar radius, due to the normal SD variability, do exist implying that the behaviour of P Cygni is more likely similar to that of R71 and S Dor but different from e.g. AG Car, R127 and HD 160529. Superimposed on the VLT component in the photometric variability of P Cygni, we observe ST

  10. Photometric observations of local rocket-atmosphere interactions

    NASA Astrophysics Data System (ADS)

    Greer, R. G. H.; Murtagh, D. P.; Witt, G.; Stegman, J.

    1983-06-01

    Photometric measurements from rocket flights which recorded a strong foreign luminance in the altitude region between 90 and 130 km are reported. From one Nike-Orion rocket the luminance appeared on both up-leg and down-leg; from a series of Petrel rockets the luminance was apparent only on the down-leg. The data suggest that the luminance may be distributed mainly in the wake region along the rocket trajectory. The luminance is believed to be due to a local interaction between the rocket and the atmosphere although the precise nature of the interaction is unknown. It was measured at wavelengths ranging from 275 nm to 1.61 microns and may be caused by a combination of reactions.

  11. Analysis of surface parametrizations for modern photometric stereo modeling

    NASA Astrophysics Data System (ADS)

    Mecca, Roberto; Rodolà, Emanuele; Cremers, Daniel

    2015-04-01

    Tridimensional shape recovery based on Photometric Stereo (PS) recently received a strong improvement due to new mathematical models based on partial differential irradiance equation ratios.1 This modern approach to PS faces more realistic physical effects among which light attenuation and radial light propagation from a point light source. Since the approximation of the surface is performed with single step method, accurate reconstruction is prevented by sensitiveness to noise. In this paper we analyse a well-known parametrization2 of the tridimensional surface extending it on any auxiliary convex projection functions. Experiments on synthetic data show preliminary results where more accurate reconstruction can be achieved using more suitable parametrization specially in case of noisy input images.

  12. A photometric study of the close binary Delta Orionis A

    NASA Astrophysics Data System (ADS)

    Koch, R. H.; Hrivnak, B. J.

    1981-08-01

    Green and blue photoelectric light curves show the historical intrinsic variability of the Delta Ori A close binary superposed on the interaction and eclipse effects. There is a considerable measure of agreement between spectrographic and photometric determinations of the rate of apsidal advance. The determinacy of orbital eccentricity, however, is confused because few minima of indifferent precision exist to check the spectrographic value. No physical mechanism can be found to account for a possible diminution of orbital eccentricity, and this is probably best attributed to unrecognized complications of at least one of the existing light curves. After numerous trials, a less-than-perfect theoretical representation of the light curve was achieved and shows the system to be detached. The absolute stellar parameters make clear that both components have evolved substantially. A mean stellar structure constant k2 is derived but cannot be compared usefully to existing theoretical values. The importance of the recently discovered visual companion, hz 42, is emphasized.

  13. A LARGE AND FAINT PHOTOMETRIC CATALOG ON THE ECLIPTIC

    SciTech Connect

    Buie, Marc W.; Trilling, David E.; Wasserman, Lawrence H.; Crudo, Richard A. E-mail: david.trilling@nau.edu E-mail: rcrudo@gmail.com

    2011-06-01

    A photometric catalog, developed for the calibration of the Deep Ecliptic Survey, is presented. The catalog contains 213,272 unique sources that were measured in V and R filters and transformed to the Johnson-Cousins systems using the Landolt standard catalog. All of the sources lie within 6{sup 0} of the ecliptic and cover all longitudes except for the densest stellar regions nearest the galactic center. Seventeen percent of the sources in the catalog are derived from three or more nights of observation. The catalog contains sources as faint as R {approx}19 but the largest fraction fall in the R {approx}15-16 (V {approx}16-17) mag range. All magnitude bins down to R = 19 have a significant fraction of objects with uncertainties {<=}0.1 mag.

  14. The LINEAR Photometric Database: Time Domain Information for SDSS Objects

    NASA Astrophysics Data System (ADS)

    Veyette, Mark; Becker, A. C.; Bozic, H.; Carroll, P.; Champey, P.; Draper, Z.; Evans, N.; Filbrandt, A.; Fowler, J.; Gailey, J.; Galin, M.; Ivezic, Z.; Jennings, Z.; Kelley, J.; Kroflin, A.; Laws, C.; Lewarch, E.; Loebman, S.; Mayorga, L.; Mesaric, M.; Morgan, D. P.; Munk, P.; Oluseyi, H.; Palaversa, L.; Patel, M.; Ruzdjak, D.; Schmidt, S.; Sesar, B.; Srdoc, G.; Steakley, K.; Stuart, J. S.; Sudar, D.; Vrbanec, D.; Westman, D. B.; Wheaton, S.; Wozniak, P.

    2012-01-01

    We announce a public database of over 5 billion photometric measurements for about 25 million objects, mostly stars with V<18, obtained by the asteroid survey LINEAR (available through the SkyDot website, skydot.lanl.gov). With 200 observations per object on average, LINEAR data provide time domain information for the brightest 4 magnitudes of SDSS survey objects. By combining information from these databases we have selected and visually classified some 200,000 candidate variable stars. Guided by these classifications, we selected the largest available sample of candidate field SX Phe stars (blue straggler halo stars) and demonstrated its low contamination through follow up observations at a number of telescopes in Croatia and the U.S. We have also constructed samples of several thousand distant RR Lyrae stars, as well as several thousand eclipsing binary stars, and are currently investigating the statistical properties of these data.

  15. Photometric Properties of Pluto and Charon: Comparison to Other Bodies

    NASA Astrophysics Data System (ADS)

    Buratti, B. J.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Ennico Smith, K.; Momary, T.; Zangari, A. M.; Binzel, R. P.

    2015-12-01

    The New Horizons spacecraft provided the first detailed views of the photometric properties of Pluto and Charon, and how these properties relate to geophysical processes. Among the first results are the distribution of albedo on the surfaces of both bodies, and the surface phase function for both high- and low-albedo regions of Pluto, which yields information on macroscopic roughness and particle properties. The highest albedos on Pluto are similar to those of the bright icy moons of Saturn and Jupiter. The range of albedos on Pluto is surprisingly large, surpassed only by Saturn's moon Iapetus. Charon has a more limited range, with a bifurcated distribution. The disk-integrated phase function of Pluto is similar to those of the icy moons of Saturn. The geologic implications of these results will be discussed. Funded by NASA

  16. Photometric approach to surface reconstruction of artist paintings

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takayuki; Tsumura, Norimichi; Nakaguchi, Toshiya; Iino, Koichi

    2011-01-01

    We propose a method for surface reconstruction of artist paintings. In order to reproduce the appearance of a painting, including color, surface texture, and glossiness, it is essential to acquire the pixel-wise light reflection property and orientation of the surface and render an image under an arbitrary lighting condition. A photometric approach is used to estimate bidirectional reflectance distribution functions (BRDFs) and surface normals from a set of images photographed by a fixed camera with sparsely distributed point light sources. A robust and computationally less expensive nonlinear optimization algorithm is proposed that optimizes the small number of parameters to simultaneously determine all of the specular BRDF, diffuse albedo, and surface normal. The proposed method can be applied to moderately glossy surfaces without separating captured images into diffuse and specular reflections beforehand. Experiments were conducted using oil paintings with different surface glossiness. The effectiveness of the proposed method is validated by comparing captured and rendered images.

  17. A Probabilistic Approach to Classifying Supernovae UsingPhotometric Information

    SciTech Connect

    Kuznetsova, Natalia V.; Connolly, Brian M.

    2006-12-14

    This paper presents a novel method for determining the probability that a supernova candidate belongs to a known supernova type (such as Ia, Ibc, IIL, etc.), using its photometric information alone. It is validated with Monte Carlo, and both space- and ground-based data. We examine the application of the method to well-sampled as well as poorly sampled supernova light curves and investigate to what extent the best currently available supernova models can be used for typing supernova candidates. Central to the method is the assumption that a supernova candidate belongs to a group of objects that can be modeled; we therefore discuss possible ways of removing anomalous or less well understood events from the sample. This method is particularly advantageous for analyses where the purity of the supernova sample is of the essence, or for those where it is important to know the number of the supernova candidates of a certain type (e.g., in supernova rate studies).

  18. New Asteroid Shape Models Derived from the Lowell Photometric Database

    NASA Astrophysics Data System (ADS)

    Durech, Josef; Hanus, J.; Vanco, R.; Oszkiewicz, D.; Bowell, E.

    2013-10-01

    Asteroid shapes and spin states can be derived from their disk-integrated sparse-in-time photometry by the lightcurve inversion method. A huge amount of sparse photometry is provided by current all-sky surveys. However, the data from surveys suffer from large random and systematic errors. Oszkiewicz et al. (2011, JQSRT 112, 1919) partly removed the systematic trends in the photometry reported to the MPC and created the so-called 'Lowell photometric database'. The database consists of re-calibrated photometry for about 500,000 asteroids, with typically hundreds of brightness measurements per object. Bowell et al. (M&PS, submitted) used this database to analyze brightness variations with ecliptic longitude and estimated spin-axis longitudes for about 350,000 asteroids. In our work, we processed data for the first 10,000 numbered asteroids with the lightcurve inversion method (Kaasalainen et al., 2001, Icarus 153,37) using an enormous computational power of Asteroids@home (http://asteroidsathome.net) - a distributed computing project built on the BOINC platform. More than 10,000 users have joined the project and their computers were used for the time-consuming search for the sidereal rotation period in the sparse data. Although the photometric accuracy of the Lowell data is low 0.2 mag), we were able to find unique models for several hundred asteroids. We will present the first results based on the statistical analysis of the sample (distribution of spin vectors, for example) and we will also discuss the relevance of our approach to Gaia, LSST, ATLAS, and other future sources of asteroid photometry with sparse sampling.

  19. Photometric and kinematic studies of extragalactic globular cluster systems

    NASA Astrophysics Data System (ADS)

    Dowell, Jessica

    Globular clusters (GCs) are old, luminous, compact collections of stars found in galaxy halos that formed during the early stages of galaxy formation. Because of this, GCs serve as excellent tracers of the formation, structure, and merger history of their host galaxies. My dissertation will examine both the photometric and kinematic properties of GC systems and their relationship to their host galaxies. In the first section, I will present the analysis of the GC systems of two spiral galaxies, NGC 891 and NGC 1055. I will discuss the photometric methods used to detect GCs using wide-field BVR imaging and to quantify the global properties of the system such as the total number of GCs and their radial distribution. My results for these two GC systems were compared to those of other galaxies. I will also present the results of spectroscopic follow-up for two giant galaxies: the S0 galaxy NGC 4594 (M104), and the elliptical galaxy NGC 3379 (M105). I measured the radial velocities of GCs in these two galaxies, and combined them with published results to determine the mass distribution and mass-to-light (M/L) ratio profile for each galaxy out to large effective radius (7-9 Re). For both galaxies, I found that the M/L profiles increase with radius and do not flatten, which suggests that the dark matter halos in these galaxies extend to the edge of my data. I also looked for evidence of rotation in the GC systems, and found that neither system exhibits significant rotation around the host galaxy. I examined the velocity dispersion profile of each GC system and found kinematic differences between the red and blue GC subpopulations. Finally, I compared my results to mass estimates for these galaxies from other kinematic tracers and considered them in the context of galaxy formation models.

  20. Miniature photometric stereo system for textile surface structure reconstruction

    NASA Astrophysics Data System (ADS)

    Gorpas, Dimitris; Kampouris, Christos; Malassiotis, Sotiris

    2013-04-01

    In this work a miniature photometric stereo system is presented, targeting the three-dimensional structural reconstruction of various fabric types. This is a supportive module to a robot system, attempting to solve the well known "laundry problem". The miniature device has been designed for mounting onto the robot gripper. It is composed of a low-cost off-the-shelf camera, operating in macro mode, and eight light emitting diodes. The synchronization between image acquisition and lighting direction is controlled by an Arduino Nano board and software triggering. The ambient light has been addressed by a cylindrical enclosure. The direction of illumination is recovered by locating the reflection or the brightest point on a mirror sphere, while a flatfielding process compensates for the non-uniform illumination. For the evaluation of this prototype, the classical photometric stereo methodology has been used. The preliminary results on a large number of textiles are very promising for the successful integration of the miniature module to the robot system. The required interaction with the robot is implemented through the estimation of the Brenner's focus measure. This metric successfully assesses the focus quality with reduced time requirements in comparison to other well accepted focus metrics. Besides the targeting application, the small size of the developed system makes it a very promising candidate for applications with space restrictions, like the quality control in industrial production lines or object recognition based on structural information and in applications where easiness in operation and light-weight are required, like those in the Biomedical field, and especially in dermatology.