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A Full Automatic Device for Sampling Small Solution Volumes in Photometric Titration Procedure Based on Multicommuted Flow System  

PubMed Central

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 (?=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 (?=930 nm) and a photodiode. When solution volume delivered from proposed device was within the range of 5 to 105 ?l, 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

Borges, Sivanildo S.; Vieira, Glaucia P.; Reis, Boaventura F.



Automatic photometric titrations of calcium and magnesium in carbonate rocks  

USGS Publications Warehouse

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.

Shapiro, L.; Brannock, W.W.




NSDL National Science Digital Library

Created by Dale Harak, Anita Salem and Paula Shorter for the Connected Curriculum Project, this is a learning modules focusing on the chemical technique of titration. This is used to determine the concentration of a substance in a solution. The purpose of this project is to construct a mathematical model describing the effects of titration, and then to use that model to determine the concentration and the identity of an acid in a solution by fitting the model to real titration data. This is one within a much larger set of learning modules hosted by Duke University.

Harak, Dale; Salem, Anita; Shorter, Paula



Photometric Quality Assurance Instrument Check Procedures.  

National Technical Information Service (NTIS)

Contents: Definitions of quality assurance practices--(Filter photometer, Single-beam spectrophotometer, Double-beam spectrophotometer, Fluorometer, Nephelometer & turbidimeter, and Densitometer); Procedures for checking instrumental parameters--(Spectrop...

L. R. Alexander, E. R. Barnhart



Within-Subject Comparison of Degree of Delay Discounting Using Titrating and Fixed Sequence Procedures  

PubMed Central

Different procedures are often used across experiments to estimate the degree of delay discounting, a common measure of impulsivity. In all procedures, participants indicate their choice between a reward available immediately and one available after a delay. The present experiment determined whether there are differences in the degree of discounting for a hypothetical $100 produced by a procedure that titrates the immediate amount (titrating sequence procedure) versus a procedure that presents a fixed sequence of immediate amounts (fixed sequence procedure) using a within-subject design. The adult human participants showed no significant differences in degree of discounting between procedures as assessed by a hyperboloid model and the Area Under the Curve. Furthermore, the Area Under the Curve values from the two procedures showed a strong positive correlation. These findings suggest there may be no systematic difference between the degree of delay discounting as estimated by the titrating sequence and fixed sequence procedures. Given the apparent similarities in the results, it appears researchers may be justified in basing their choice of which procedure to use on convenience. PMID:20932882

Rodzon, Katrina; Berry, Meredith S.; Odum, Amy L.



Photometric parameters Photometric evolution  

E-print Network

Outline Photometric parameters Photometric evolution Population synthesis STRUCTURE OF GALAXIES 4. Photometric parameters and evolution Piet van der Kruit Kapteyn Astronomical Institute University of Groningen and evolution #12;Outline Photometric parameters Photometric evolution Population synthesis Outline Photometric

Kruit, Piet van der


Digital image-based titrations.  


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. PMID:17723410

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



Titration vs. Tradition  

Microsoft Academic Search

The way titration curves are traditionally taught in the undergraduate curriculum is reviewed, and a more rational approach is advocated. A spreadsheet is then used to illustrate the various properties of titration curves and to fit titration data.

Robert de Levie



Milk Lipase System. III. Further Studies of the Solvent Extraction Procedure for Obtaining Fat from Milk for Titration1  

Microsoft Academic Search

In previous work (5) a solvent extraction procedure was developed which proved superior to standard churning methods for the obtaining of fat in milk lipase studies. However, even this solvent method was found to be inefficient in removing butyric and caproic acids from cream. Thus, it seemed desirable to modify the extraction method to obtain greater recovery of the fatty

B. C. Johnson; I. A. Gould



Reproducibility of a Standardized Titration Procedure for the Initiation of Continuous Positive Airway Pressure Therapy in Patients with Obstructive Sleep Apnoea  

Microsoft Academic Search

Background: Manual titration of continuous positive airway pressure (CPAP) under polysomnographic control is the method most commonly employed to establish the minimal effective pressure (Peff) for the treatment of the obstructive sleep apnoea syndrome (OSA). To date, however, the reproducibility of Peff titrated in this way has not been investigated in any detail. Objectives: The present study aims to establish

G. H. Wiest; F. S. Fuchs; I. A. Harsch; S. Pour Schahin; S. Lampert; W. M. Brueckl; E. G. Hahn; J. H. Ficker



An Environmental Friendly Procedure for Photometric Determination of Hypochlorite in Tap Water Employing a Miniaturized Multicommuted Flow Analysis Setup  

PubMed Central

A photometric procedure for the determination of ClO? in tap water employing a miniaturized multicommuted flow analysis setup and an LED-based photometer is described. The analytical procedure was implemented using leucocrystal violet (LCV; 4,4?,4??-methylidynetris (N,N-dimethylaniline), C25H31N3) as a chromogenic reagent. Solenoid micropumps employed for solutions propelling were assembled together with the photometer in order to compose a compact unit of small dimensions. After control variables optimization, the system was applied for the determination of ClO? in samples of tap water, and aiming accuracy assessment samples were also analyzed using an independent method. Applying the paired t-test between results obtained using both methods, no significant difference at the 95% confidence level was observed. Other useful features include low reagent consumption, 2.4??g of LCV per determination, a linear response ranging from 0.02 up to 2.0?mg?L?1??ClO?, a relative standard deviation of 1.0% (n = 11) for samples containing 0.2?mg?L?1??ClO?, a detection limit of 6.0??g?L?1??ClO?, a sampling throughput of 84 determinations per hour, and a waste generation of 432??L per determination. PMID:21747732

Borges, Sivanildo S.; Reis, Boaventura F.



A compact titration configuration for process analytical applications  

Microsoft Academic Search

A configuration for wet-chemical process analysis is proposed consisting of one piston burette, a selector valve and a reaction cell. The feasibility of the configuration is shown by optimising a simple acid\\/base titration setup. Other applications of this configuration for complexometric-, precipitation-, and back-titration, standard addition and photometric methods are discussed. The configuration offers great flexibility towards these methods without

Robert Hoogendijk



Calibrationless Determination of Creatinine and Ammonia by Coulometric Flow Titration  

Microsoft Academic Search

A precise and sensitive working microflow titration procedure was developed to determine creatinine and ammonia in urine samples. This procedure is based on enzymatic conversion of creatinine, gas diffusional membrane separation of the released ammonia into an acid acceptor stream, and coulometric titration of ammonia with hypobromite. The hypobromite is formed after the electrogeneration of bromine in an electrolyte containing

Z. K. He; B. Fuhrmann; U. Spohn



Luminescence titrations of polyelectrolytes  

E-print Network

LUMINESCENCE TITRATIONS OF POLYELECTROLYTES A Thesis by EDWIN RENE ALVAREZ Submitted to the Graduate college of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1986 Major subject...: Chemistry LUMINESCENCE TITRATIONS OF POLYELECTROLYTES A Thesis by EDWIN RENE ALVAREZ Approved as to style and content by: harles R. Martin (Chair of Committee) Marvin W. Rowe (Member) , 3 James F. Haw (Member) Donald W. Pettig ew (Member...

Alvarez, Edwin Rene



Digital image-based titrations  

Microsoft Academic Search

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

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



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

NASA Technical Reports Server (NTRS)

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.

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



Spectrophotometric Titration of a Mixture of Calcium and Magnesium.  

ERIC Educational Resources Information Center

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…

Fulton, Robert; And Others



Spectrophotometric titration of zirconium in siliceous materials.  


An accurate and selective complexometric titration procedure based upon a spectrophotometrically detected end-point has been developed for the determination of zirconium in glasses, glass-ceramics and refractories. A p-bromomandelic acid separation step for zirconium imparts excellent selectivity to the procedure. The method is particularly important for the 1-5% concentration range where a simple, accurate and selective method for the determination of zirconium has been lacking. PMID:18962344

Sugawara, K F; Su, Y S; Strzegowski, W R


Fibre-optic titrations-IV Direct complexometric titration of aluminium(III) with DCTA.  


The end-point of the direct complexometric titration of Al(3+) in pH 4.6 solution can be determined by monitoring the fluorescence intensity of the aluminium-morin complex, by use of a bifurcated fibre-optic light guide. The method allows the determination of aluminium in the 1-800 ppm range with good precision. The procedure is applicable even when the solutions are strongly coloured or turbid, but because of the slow complexation kinetics requires a titration time of about 20 min. PMID:18964217

Wolfbeis, O S; Schaffar, B P; Chalmers, R A



Acid-Base Titration Applet  

NSDL National Science Digital Library

Acid-Base titration applet that plots pH changes as student adds acid or base. Gives choice of indicators (only two right now). Compares plots for titration of traditional solution and a buffered solution (several choices for comparison). Can alter starting concentrations.



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

ERIC Educational Resources Information Center

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…

Kangas, Brian D.; Branch, Marc N.



Selective determination of gas dialysable components in complex sample solutions using triangle programmed coulometric titration in continuous flow systems  

Microsoft Academic Search

A precisely and sensitively working coulometric flow titration procedure was developed to determine ammonium\\/ammonia and sulphide\\/hydrogen sulphide in leachate from a municipal waste landfill site. The selectivity of coulometric titration with electrogenerated hypobromite could be essentially improved by the combination with a continuously and quantitatively working thin layer gas dialysis cell, which was integrated in the flow titration setup in

M Becker; B Fuhrmann; U Spohn



Standard Photometric Systems  

NASA Astrophysics Data System (ADS)

Standard star photometry dominated the latter half of the twentieth century reaching its zenith in the 1980s. It was introduced to take advantage of the high sensitivity and large dynamic range of photomultiplier tubes compared to photographic plates. As the quantum efficiency of photodetectors improved and the wavelength range extended further to the red, standard systems were modified and refined, and deviations from the original systems proliferated. The revolutionary shift to area detectors for all optical and IR observations forced further changes to standard systems, and the precision and accuracy of much broad- and intermediate-band photometry suffered until more suitable observational techniques and standard reduction procedures were adopted. But the biggest revolution occurred with the production of all-sky photometric surveys. Hipparcos/Tycho was space based, but most, like 2MASS, were ground-based, dedicated survey telescopes. It is very likely that in the future, rather than making a measurement of an object in some standard photometric system, one will simply look up the magnitudes and colors of most objects in catalogs accessed from the Virtual Observatory. In this review the history of standard star photometry will be outlined, and the calibration and realization of standard systems will be examined. Finally, model atmosphere fluxes are now very realistic, and synthetic photometry offers the best prospects for calibrating all photometric systems. Synthetic photometry from observed spectrophotometry should also be used as a matter of course to provide colors within standard systems and to gain insights into the spectra and colors of unusual stars, star clusters and distant galaxies.

Bessell, Michael S.



Amperometric, Bipotentiometric, and Coulometric Titration.  

ERIC Educational Resources Information Center

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…

Stock, John T.



The effects of solubility, ionization, and polarity on end points in high frequency titrations  

E-print Network

of the titx'ation product sauee4 a heavy loa4ing on the cecil latox' ~ Continual dissolut ion an4 ionisat Lcn of tho titration product with the addition of the titrant solvents caused the loading which chaxactex'ised the acid titration curves. A titrant... and Standardisation ef Reagents Procedure Disoussion of Experijsontal Results Tho Effeot of the Dielectric Constants of the Solvents The Initial Solubility of tho Titration Product Tho Slope of a Titration Cmve Loading by Exoass Titrant Tho Insoluble Product...

White, James Decker



Back titration with mercuric nitrate in alkaline medium  

Microsoft Academic Search

The back titration procedure making use of mercuric nitrate as back titrant for excess EDTA in alkaline media, has been successfully applied for the determination of small amounts of scandium or palladium in the order of 0.045 to 7 or 0.1 to 4mg, respectively. Simple procedures are given for the analysis of binary or ternary mixtures of scandium or palladium

H. Khalifa; M. M. Khater



Surface Titrations of Perlite Suspensions  

Microsoft Academic Search

The surface charge behaviour of unexpanded and expanded perlite samples in KNO3and NaCl solutions were investigated as a function of pH and ionic strength. The solutions of KNO3and NaCl ranging from 10?3to 1.0Mwere 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

Mahir Alkan; Mehmet Do ?



Direct complexometric titration of calcium phosphates.  


Calcium was determined in calcium phosphate samples by dissolving the sample in hydrochloric acid, adding hydroxynaphthol blue indicator and triethanolamine, adjusting the pH to 12.3--12.5 with potassium hydroxide solution, and titrating with standard disodium ethylenediaminetetraacetate solution. Time can be saved and the formation of a precipitate (which dissolves readily during the titration) can be avoided by adding at least 85% of the amount of complexing agent required for titration before adjusting the pH. PMID:903881

Tuckerman, M M; Sanchez de Ramos, M E



Determination of Solanesol by Coulometric Titration  

Microsoft Academic Search

A method for determination of solanesol by coulometric titration was developed. The titration was carried out in a mixture of 2M KBr-glacial acetic acid (22:78 v\\/v), and bromine was generated at the anode. Solanesol reacted with bromine with a value of n = 18. The end point of the titration was detected with two-electrode amperometry. The method is rapid, accurate

Kuai Zhi Liu; Meng Liu; Deliang Li



A new radiometric titration method based on separation by means of ion exchange  

Microsoft Academic Search

A mathematical expression is derived for the radiocomplexometric determination of a mixture of two metals with one ligand,\\u000a using an anion exchanger in the solution as a phase separating system. An expression is also given for the complexometric\\u000a titration of a metal, when formation of acidic or basic complexes is taken into account. In the experimental part titration\\u000a procedures are

A. Heijink; H. L. Polak



A new radiometric titration method based on separation by means of ion exchange  

Microsoft Academic Search

The determination of zinc with EDTA is chosen as an example for the earlier suggested new radio-complexometric titration procedure,\\u000a in which phase separation is achieved by means of a strongly basic anion exchanger in the solution. Concentrations of zinc\\u000a solutions down to 10?6\\u000a M have been determined. The reverse titration,viz. of EDTA with zinc solution, which can be used as

A. Heijink; H. L. Polak



Photometric Lunar Surface Reconstruction  

NASA Technical Reports Server (NTRS)

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.

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



Potentiometric titration of calcium in seawater  

Microsoft Academic Search

By using calcium ion selective electrode (Ca ISE) as indicating electrode, saturated calomel electrode (SCE) as reference\\u000a electrode and EGTA as titrant, calcium in seawater was determined by potentiometric titration in borate buffer solution. This\\u000a method can reduce observation errors in the determination of the endpoint, and thus provide better analytical precision (<0.08%)\\u000a than present complexometric titration.

Shi-Nan Xie; Hong Ji; Ai-Qin Wu; Guo-Hua Chen



A Critical Assessment of Photometric Redshift Methods: A CANDELS Investigation  

NASA Astrophysics Data System (ADS)

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.

Dahlen, Tomas; Mobasher, Bahram; Faber, Sandra M.; Ferguson, Henry C.; Barro, Guillermo; Finkelstein, Steven L.; Finlator, Kristian; Fontana, Adriano; Gruetzbauch, Ruth; Johnson, Seth; Pforr, Janine; Salvato, Mara; Wiklind, Tommy; Wuyts, Stijn; Acquaviva, Viviana; Dickinson, Mark E.; Guo, Yicheng; Huang, Jiasheng; Huang, Kuang-Han; Newman, Jeffrey A.; Bell, Eric F.; Conselice, Christopher J.; Galametz, Audrey; Gawiser, Eric; Giavalisco, Mauro; Grogin, Norman A.; Hathi, Nimish; Kocevski, Dale; Koekemoer, Anton M.; Koo, David C.; Lee, Kyoung-Soo; McGrath, Elizabeth J.; Papovich, Casey; Peth, Michael; Ryan, Russell; Somerville, Rachel; Weiner, Benjamin; Wilson, Grant




SciTech Connect

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.

Dahlen, Tomas; Ferguson, Henry C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Faber, Sandra M.; Barro, Guillermo; Guo, Yicheng [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Finkelstein, Steven L. [Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 (United States); Finlator, Kristian [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen (Denmark); Fontana, Adriano [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040, Monteporzio (Italy); Gruetzbauch, Ruth [Center for Astronomy and Astrophysics, Observatorio Astronomico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa (Portugal); Johnson, Seth [Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Pforr, Janine; Dickinson, Mark E. [NOAO, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Salvato, Mara; Wuyts, Stijn [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany); Wiklind, Tommy [Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago (Chile); Acquaviva, Viviana [Physics Department, CUNY NYC College of Technology, 300 Jay Street, Brooklyn, NY 11201 (United States); Huang, Jiasheng [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Huang, Kuang-Han [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Newman, Jeffrey A., E-mail: [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); and others



A Monte Carlo Study of Titrating Polyelectrolytes  

E-print Network

A Monte Carlo Study of Titrating Polyelectrolytes Magnus Ullnery and Bo Jonssonz Physical Chemistry Journal of Chemical Physics 104, 3048-3057 (1996) Monte Carlo simulations have been used to study three di the conformations towards more extended structures. In the Monte Carlo simulations presented here, focus

Peterson, Carsten


A Monte Carlo Study of Titrating Polyelectrolytes  

E-print Network

A Monte Carlo Study of Titrating Polyelectrolytes Magnus Ullner y and Bo J¨onsson z Physical, Sweden Journal of Chemical Physics 104, 3048­3057 (1996) Monte Carlo simulations have been used to study of the polymer more difficult and biases the conformations towards more extended structures. In the Monte Carlo

Peterson, Carsten


Coulometric titration of ketotifen in tablets.  


A method for the determination of ketotifen involving its reaction with iodine in an alkaline medium is presented. In coulometric titration using biamperometric end-point detection 0.25-2 micromol (77-618 microg) of ketotifen was successfully determined. The elaborated method was applied to the determination of ketotifen in drugs. PMID:15801682

Ciesielski, W; Zakrzewski, R; Z?obi?ska, U



Isothermal Titration Calorimetry in the Student Laboratory  

ERIC Educational Resources Information Center

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…

Wadso, Lars; Li, Yujing; Li, Xi



Titration Calculations with Computer Algebra Software  

ERIC Educational Resources Information Center

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,…

Lachance, Russ; Biaglow, Andrew



Tracer monitored titrations: measurement of total alkalinity.  


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 equivalence point. Although applied to acid-base titrations in this paper, the approach should be generally applicable to other types of titrations. PMID:16536416

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



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

ERIC Educational Resources Information Center

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…

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



Determination of nitric acid in highly radioactive solutions by the method of coulometric titration  

Microsoft Academic Search

A procedure, a cell, and an electronic block have been developed for a long-distance determination of nitric acid in highly radioactive industrial solutions by coulometric titration under hot chamber conditions. A solution of a mixture of ammonium and potassium oxalates was used for the background and anoide electrolytes. This solution prevents the hydrolysis of the metal ions and appreciably decreases

V. S. Gromov; A. Ya. Kuperman; Yu. A. Smirnov



Photoelectric end-point determination in the titration of fluorides with thorium nitrate  

Microsoft Academic Search

A procedure used for the determination of fluorides in plant tissue and in air is described. A photoelectric filter photometer functioning as a comparator is used for the determination of the end point in the titration of fluorides (F) with thorium nitrate (Th(NOâ)â) in the presence of sodium alizarinsulfonate. It is a balance type instrument consisting of a nearly monochromatic

R. Mavrodineanu; J. Gwirtsman



Simultaneous titration of ternary alkaline-earth mixtures employing a potentiometric electronic tongue  

Microsoft Academic Search

A fast novel complexometric titration procedure is proposed, in which\\u000a equivalence concentrations were determined using a potentiometric\\u000a electronic tongue. The titration consists in a reduced number of fixed\\u000a additions of titrant and the recording of the potentials of an array of\\u000a ion-selective electrodes with cross-selectivity response. The generated\\u000a data (number of sensors x number of additions) were used as input

Daniel Calvo; Manuel del Valle



Photometric Redshifts of Galaxies in COSMOS  

NASA Astrophysics Data System (ADS)

We present photometric redshifts for the COSMOS survey derived from a new code, optimized to yield accurate and reliable redshifts and spectral types of galaxies down to faint magnitudes and redshifts out to z~1.2. The technique uses ?2 template fitting, combined with luminosity function priors and with the option to estimate the internal extinction [or E(B-V)]. The median most probable redshift, best-fit spectral type and reddening, absolute magnitude, and stellar mass are derived in addition to the full redshift probability distributions. Using simulations with sampling and noise similar to those in COSMOS, the accuracy and reliability is estimated for the photometric redshifts as a function of the magnitude limits of the sample, S/N ratios, and the number of bands used. We find from the simulations that the ratio of derived 95% confidence interval in the ?2 probability distribution to the estimated photometric redshift (D95) can be used to identify and exclude the catastrophic failures in the photometric redshift estimates. To evaluate the reliability of the photometric redshifts, we compare the derived redshifts with high-reliability spectroscopic redshifts for a sample of 868 normal galaxies with z<1.2 from zCOSMOS. Considering different scenarios, depending on using prior, no prior, and/or extinction, we compare the photometric and spectroscopic redshifts for this sample. The rms scatter between the estimated photometric redshifts and known spectroscopic redshifts is ?(?(z))=0.031, where ?(z)=(zphot-zspec)/(1+zspec) with a small fraction of outliers (<2.5%) [outliers are defined as objects with ?(z)>3?(?(z)), where ?(?(z)) is the rms scatter in ?(z)]. We also find good agreement [?(?(z))=0.10] between photometric and spectroscopic redshifts for type II AGNs. We compare results from our photometric redshift procedure with three other independent codes and find them in excellent agreement. We show preliminary results, based on photometric redshifts for the entire COSMOS sample (to i<25 mag). Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555 also based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; the European Southern Observatory under Large Program 175.A-0839, Chile; Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and the National Optical Astronomy Observatory, which are operated by the AURA, Inc., under cooperative agreement with the National Science Foundation; the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.; and the Canada-France-Hawaii Telescope with MegaPrime/MegaCam operated as a joint project by the CFHT Corporation, CEA/DAPNIA, the National Research Council of Canada, the Canadian Astronomy Data Centre, the Centre National de la Recherche Scientifique de France, TERAPIX, and the University of Hawaii.

Mobasher, B.; Capak, P.; Scoville, N. Z.; Dahlen, T.; Salvato, M.; Aussel, H.; Thompson, D. J.; Feldmann, R.; Tasca, L.; Le Fevre, O.; Lilly, S.; Carollo, C. M.; Kartaltepe, J. S.; McCracken, H.; Mould, J.; Renzini, A.; Sanders, D. B.; Shopbell, P. L.; Taniguchi, Y.; Ajiki, M.; Shioya, Y.; Contini, T.; Giavalisco, M.; Ilbert, O.; Iovino, A.; Le Brun, V.; Mainieri, V.; Mignoli, M.; Scodeggio, M.



[Estimation of sulfhydryl groups by laboratory titrator T-201].  


A method for estimating sulfhydryl groups by laboratory titrator T-201 is proposed. It consists in culonometric titration of SH-groups by silver ions. The method is highly sensitive and reproducible. PMID:7378573

Aleksidze, N G; Koshoridze, N I



Determination of some antipsychotropic and anticholinergic phenothiazine drugs by vanadium (V) titration  

Microsoft Academic Search

Three simple, rapid and accurate titrimetric procedures using ammonium metavanadate have been developed for the determination of six phenothiazine drags in pure form and in dosage forms. The procedures are based on the oxidation of phenothiazines in acid medium to colourless sulphoxides via orange or purple coloured intermediates. In the first method, phenothiazines are titrated directly in H2SO4-H3PO4 medium to

K. Basavaiah; G. Krishnamurthy



Photometric Subluminous Type Ia Supernovae  

NASA Astrophysics Data System (ADS)

We present a new photometric identification technique for subluminous type Ia supernovae capable of selecting out this subgroup from the normal type Ia population. The technique reveals that a proper subluminous definition needs to include color besides light-curve width. Furthermore, it can be used to identify a variety of newly discovered peculiar type Ia supernovae demonstrating photometric similarities between these different objects.

González Gaitán, S.



Photometric determination of dissolved oxygen with iron(II) cacotheline oxalate blue  

Microsoft Academic Search

Iron (II)-cacotheline-oxalate blue solution is used as reductometric reagent for the estimation of dissolved oxygen. By titrating the blue complex solution photometrically, the dissolved oxygen in water samples can be accurately determined in the range of 2 to 8 mg\\/l. The stoichiometry of the reaction between dissolved oxygen and the blue complex was found to be 1:0.8 or 5:4. The

N. Krishna Murthy; S. L. Narasimha Rao; D. R. R. Sarma



Kinetic Titration Series with Biolayer Interferometry  

PubMed Central

Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1–42). Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i) circumvents problems in data evaluation caused by unavoidable sensor differences, ii) saves resources and iii) increases throughput if screening a multitude of different analyte/ligand combinations. PMID:25229647

Frenzel, Daniel; Willbold, Dieter



Graphical evaluation of complexometric titration curves.  


A graphical method, based on logarithmic concentration diagrams, for construction, without any calculations, of complexometric titration curves is examined. The titration curves obtained for different kinds of unidentate, bidentate and quadridentate ligands clearly show why only chelating ligands are usually used in titrimetric analysis. The method has also been applied to two practical cases where unidentate ligands are used: (a) the complexometric determination of mercury(II) with halides and (b) the determination of cyanide with silver, which involves both a complexation and a precipitation system; for this purpose construction of the diagrams for the HgCl(2)/HgCl(+)/Hg(2+) and Ag(CN)(2)(-)/AgCN/CN(-) systems is considered in detail. PMID:18963841

Guinon, J L



Determination of carbonate carbon in geological materials by coulometric titration  

USGS Publications Warehouse

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.

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




E-print Network

LABORATORY EXPERIMENT 6 PRECIPITATION TITRATION WITH SILVER NITRATE. The AgNO3 solution (~0.02 M in the titration of chloride ion with silver nitrate. The first excess of titrant results in the formation of a red Ag2CrO4. Calculations: From the volume of silver nitrate solution used fopr titration, calculate

Nazarenko, Alexander



E-print Network

LABORATORY EXPERIMENT 5 PRECIPITATION TITRATION WITH SILVER NITRATE. The AgNO3 solution (~0.02 M in the titration of chloride ion with silver nitrate. The first excess of titrant results in the formation of a red Ag2CrO4. Calculations: From the volume of silver nitrate solution used fopr titration, calculate

Nazarenko, Alexander


Monitoring denitrification by pH-Stat titration.  


An improved pH-stat titrimetric procedure was developed, validated, and extensively applied to monitor biological heterotrophic denitrification in a lab-scale sequencing batch reactor (SBR). So far, titrimetric procedures were not successful in monitoring denitrification processes in full-scale wastewater (WW) treatment plants, mainly because the stoichiometric ratio between proton production and nitrate reduction is highly variable due to variability of both biomass and influent WW characteristics. In this article, a new titration procedure is proposed where a simple calibration step is performed before each experimental test. This procedure allows for the assessment of (i) nitrate content in a sample of mixed liquor; (ii) the maximum denitrification rate of sludge when fed on acetate; and (iii) the denitrification potential (DNP) of different substrates. As for (i), validation by comparison with spectrophotometric measures indicated an average discrepancy of less than 3% on more than 40 samples; as for (ii) and (iii) collected values compared well with literature data. The titrimetric method proposed here is also capable of assessing the biomass anoxic yield in a very simple way, since it does not require any analytical nitrate determination. According to the results of this experimentation, titrimetry appeared to be a simple, inexpensive, and powerful tool for monitoring and operating denitrification processes in WW treatment plants. PMID:17721878

Ficara, Elena; Canziani, Roberto



GTC Photometric Calibration  

NASA Astrophysics Data System (ADS)

We are currently developing the calibration programme for GTC using techniques similar to the ones use for the space telescope calibration (Hammersley et al. 1998, A&AS, 128, 207; Cohen et al. 1999, AJ, 117, 1864). We are planning to produce a catalogue with calibration stars which are suitable for a 10-m telescope. These sources will be not variable, non binary and do not have infrared excesses if they are to be used in the infrared. The GTC science instruments require photometric calibration between 0.35 and 2.5 microns. The instruments are: OSIRIS (Optical System for Imaging low Resolution Integrated Spectroscopy), ELMER and EMIR (Espectrógrafo Multiobjeto Infrarrojo) and the Acquisition and Guiding boxes (Di Césare, Hammersley, & Rodriguez Espinosa 2005, RevMexAA Ser. Conf., 24, 231). The catalogue will consist of 30 star fields distributed in all of North Hemisphere. We will use fields containing sources over the range 12 to 22 magnitude, and spanning a wide range of spectral types (A to M) for the visible and near infrared. In the poster we will show the method used for selecting these fields and we will present the analysis of the data on the first calibration fields observed.

di Cesare, M. A.; Hammersley, P. L.; Rodriguez Espinosa, J. M.



Modeling complexometric titrations of natural water samples.  


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 (approximately 10 nM) of high-affinity, Cu-binding ligands over [CU]T results in low equilibrium [Cu2+] of 10(-14.5 +/- 0.2) M and 10(-13.3 +/- 0.4) M, respectively. PMID:12731837

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



Measuring titratable alkalinity by single versus double endpoint titration: An evaluation in two cyprinodont species and implications for characterizing net H+  

E-print Network

Measuring titratable alkalinity by single versus double endpoint titration: An evaluation in two Fundulus heteroclitus Na+ homeostasis Acid­base balance Titratable alkalinity Ammonia Net H+ transport were the result of using double endpoint titrations to measure titratable alkalinity fluxes

Grosell, Martin


Systemic Errors In Quantitative PCR Titration of Self-Complementary AAV Vectors and Improved Alternative Methods  

PubMed Central

Self-complementary AAV (scAAV) vector genomes contain a covalently closed hairpin derived from a mutated inverted terminal repeat which 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. Additionally, we developed and present an AAV genome titration procedure based on gel electrophoresis that requires minimal sample processing and has very low inter assay variability, and as such is well suited for the rigorous quality control demands of clinical vector production facilities. PMID:22428975

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



The acid-base titration of montmorillonite  

NASA Astrophysics Data System (ADS)

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 data illustrates the complementarity of molecular and macro-scale descriptions of the clay reactivity.

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



An accurate method of iodometric titration to measure copper valence of high- T c superconductors  

Microsoft Academic Search

The double iodometric titration is the method widely used to determine copper valence of high-T\\u000a c superconductors. There are some problems that remain to be solved, and certain procedures are used: adding KSCN to release\\u000a adsorbed iodine, adding HN4HF2 to eliminate the interference of some dopants, and using a new calculating equation to accurately calculate experiment results.\\u000a Al- and Fe-doped

W. M. Chen; X. S. Wu; J. F. Geng; J. Chen; D. B. Chen; X. Jin; S. S. Jiang



[Determination of the sulfate ion content in antibiotic sulfate salts by a complexometric titration method].  


A possibility of assaying antibiotic sulfates, such as gentamicin, kanamycin, monomycin, neomycin, ristomycin, streptomycin, florimycin and polymyxin M sulfates for sulfate ions by titration with barium chloride in the presence of chlorphosphonaso-III, a metal indicator immediately in the salt solutions or after elimination of the cation by means of ion exchange (sulfocation exchange resins in H+-form) was tested. The procedure was shown to be adequate to the classical weight method. PMID:7469396

Kartseva, V D; Lokshin, G B; Libinson, G S; Kruzhkova, N G



A Simple Karl Fischer Titration Technique for Measuring the Silanol Content of High Molecular Weight Polysiloxanes  

Microsoft Academic Search

This article presents a simple technique for measuring the silanol (SiOH) content of polysiloxanes having molecular weights of 26,000 amu or more. It extends an earlier procedure, in which 50°C methanol converts each silanol group into a methoxy group (SiOCH3) and the resulting water is measured by Karl Fischer titration. Unlike previous work, however, the present technique dissolves the high molecular

Louis A. Bloomfield



Potentiometric titration of chloride in plant tissue extracts using the chloride ion electrode  

Microsoft Academic Search

Use of the chloride specific ion electrode to determine chloride in plants was evaluted. Direct potentiometric determination of chloride by the electrode resulted in unreproducible and extremely high chloride values. However, use of this electrode to indicate the end point in titration of the tissue?extract mixture with AgNO3 gave results nearly identical to those obtained by the Mohr procedure. The

R. L. LaCroix; D. R. Keeney; L. M. Walsh



Automated titration method for use on blended asphalts  


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.

Pauli, Adam T. (Cheyenne, WY); Robertson, Raymond E. (Laramie, WY); Branthaver, Jan F. (Chatham, IL); Schabron, John F. (Laramie, WY)



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

NASA Astrophysics Data System (ADS)

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.

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



Automated Titrations with AN Alternate Flow, Linear Speed, Variation System. Applications to Amperometric, Biamperometric, and Spectrophotometric Titrations  

Microsoft Academic Search

The “alternate flow” method was recently proposed as a solution to the problem connected to the requirement of frequent calibrations of systems utilizing peristaltic pumps.This method was successfully applied to amperometric titrations of the ferrous–ceric system, biamperometric titrations of arsenite–iodine and thiosulfate–iodine systems, and spectrophotometric titrations of ferrous–permanganate and arsenite–iodine systems. Equivalence point determination is possible in the micromolar range

Tatyana A. Bendikov; Chaim N. Yarnitzky



A Closer Look at Acid-Base Olfactory Titrations  

ERIC Educational Resources Information Center

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.

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



Quantitative Analysis of Sulfate in Water by Indirect EDTA Titration  

ERIC Educational Resources Information Center

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.…

Belle-Oudry, Deirdre



Successive determination of praseodymium and ytterbium by coulometric complexometric titration  

Microsoft Academic Search

A method is described for the successive coulometric complexometric titration of microgram levels of light and heavy rare earth elements. The total amount of light and heavy rare earth elements is titrated by electrogenerating titrant EDTA on the mercury pool as a cathode. Then, the mercury pool is switched as an anode, electrogenerating Hg\\/sup 2 +\\/, and is used to

S. Chun-Nian; L. Jing-Ci; N. Qi-Dao; C. Mou-Sen



Characterization of Petroleum Sulfonates by a Nonaqueous Titration Method  

Microsoft Academic Search

A new method is described for the determination of the equivalent weight for petroleum sulfonates. The method is based on the direct acidimetric titration of the sulfonate in acetic acid\\/acetic anhydride solvent using a titrant of perchloric acid in dioxane. From the titration, the moles of perchloric acid required to react with the sulfonate is measured. The equivalent weight is

Kim Voss; Clark Bricker; M. J. Michnick; G. P. Willhite



Back titration with mercuric nitrate in alkaline medium analysis of tertiary mixtures of mercury(II) with some other metals  

Microsoft Academic Search

Tertiary mixtures each containing mercury(II) were analysed by simple procedures involving combination between the recent method of back titration with mercuric nitrate in alkaline medium, and the volumetric methods which make use of masking agents as cyanide. The content of mercury(II) in most mixtures is determined potentiometrically with potassium iodide using the silver amalgam as indicator electrode. End points are

H. Khalifa; Farouk A. Osman



Spectrophotometric titration of ionisable groups in proteins: a theoretical study  

NASA Astrophysics Data System (ADS)

A simple theoretical model is proposed for evaluation of the optical titration behaviour of tyrosyl and carboxyl residues in proteins. The p K values involved in the model are computed using the semi-empirical method. The titration curves are calculated using the values of the molar absorption differences for tyrosyl residues in the ultraviolet (UV) region at 245 and 295 nm, and for carboxyl residues in the infrared (IR) region at 1565 and 1707 cm -1, respectively. The theoretical tyrosyl titration curves are compared with the experimental data for lysozyme, myoglobin and chymotrypsinogen (available in the literature). This approach provides a good tool for distinguishing between the ionisation and the conformational changes in the alkaline range. The quantitative evaluation of the change of molar extinction coefficients as a function of pH in the case of carboxyl titration for lysozyme, trypsin and cytochrome c shows a good agreement with the experimental titration data.

Miteva, Maria; Shosheva, Alexandra; Atanasov, Boris



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

SciTech Connect

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.

Fergg, F. [Technische Universitaet Muenchen (Germany); Kuehner, D.E.; Blanch, H.W.; Prausnitz, J.M. [Lawrence Berkeley Lab., CA (United States)



Visual photometric experiment data analysis  

NASA Astrophysics Data System (ADS)

The Visual Photometric Experiment (VIPER) is an instrument package designed for a shuttle-borne Get-Away Special canister. Data processing and analysis developments for the VIPER are described, including support for the camera and visual radiometer processing, pre-flight laboratory calibration, and development of the star field matching algorithm for the post flight pointing determination.

Mzaaella, Andrew J., Jr.; Larson, Kevin P.



Photometric Redshifts: 50 Years After  

NASA Astrophysics Data System (ADS)

Almost half a century has passed since Baum [1] first applied a novel method to a handful of galaxies. Using the mean spectral energy distribution (SED) of six bright ellipticals in the Virgo cluster, he could accurately estimate the redshifts of other clusters in a comparison that we today call SED fitting or, more generally, photometric redshifts. Owing to the expansion of the Universe, galaxies farther away appear to be redder. Their observed colors are a combination of this redshift and their intrinsic properties. Thanks to the latest detector technology, today we can undertake deep, multicolor surveys to probe statistically meaningful volumes. The yield of photometry in terms of the number of sources is over two orders of magnitude higher than what is achievable by (the more accurate) spectroscopic follow-ups. To exploit the information in the photometric data themselves, several new methods have been developed over the years. One particular successful example is the estimation of photometric redshifts. Baum's motivation for using photometric measurements instead of spectroscopy was the same back then as ours is now: to push the analyses to uncharted territories. His original idea has grown into a research area of its own, which is more important now than ever before. In this chapter, we look at some of the recent advancements of the field. In Section 15.2 we briefly highlight some of the original ideas and the current state of the art in estimating the photometric redshifts. Section 15.3 introduces a Bayesian framework for discussing the traditional methods within a unified context; it explicitly enumerates and identifies their (missing) ingredients. Section 15.4 aims to plant seeds for new ideas for future directions, and Section 15.5 offers some concluding remarks.

Budavári, Tamás



Robust flow-batch coulometric/biamperometric titration system: determination of bromine index and bromine number of petrochemicals.  


A flow-batch system was constructed and evaluated to perform coulometric titrations with biamperometric end point detection. The flow section of the system is employed for sampling by injecting a sample volume (50-300 microL) in a flow injection-like system. About 1.5 mL of a suitable carrier solution is delivered by a peristaltic pump in order to quantitatively transfer the sample to the system titration cell (2.0 mL total inner volume). The carrier contains the coulometric precursor for the titrant species. The cell contains two pairs of platinum electrodes used for coulometric generation of reagent and biamperometric detection and is actively stirred. The titrant species is generated and the titration is performed by the usual batch procedure with the excess of titrant being detected by biamperometry following the analysis of the titration curve. System operation is computer controlled and all operations are automated, including titration curve analysis and cell cleaning after the titration is ended. The system is characterized by its robustness because its operation does not depend on flow rates, and the work using coulometric methods which generate gases at the counter-electrode is not troublesome. The flow-batch system has been evaluated for determination of bromine index and bromine number (relative to the total reactive olefin content) in petrochemicals according to an ASTM procedure. Typical precision (R.S.D.) is between 0.5 and 6% for different petrochemicals whose bromine number/index vary from 1000 to 10mg of bromine per 100g of sample, respectively. Recoveries for standard additions are between 92 and 123% for 10mg of Br(2) per 100g increments and 98 to 101% for 100mg per 100g increments. Accuracy of the proposed system was evaluated against results obtained by the standard ASTM with no significant difference detected at 95% confidence level. PMID:17903468

Pasquini, Celio; de Aquino, Emerson Vidal; das Virgens Reboucas, Marcio; Gonzaga, Fabiano Barbieri



Photometric Science Alerts from Gaia  

E-print Network

Gaia is the cornerstone mission of the European Space Agency. From late 2013 it will start collecting superb astrometric, photometric and spectroscopic data for around a billion of stars of our Galaxy. While surveying the whole sky down to V=20mag Gaia will be detecting transients and anomalous behaviour of objects, providing near-real-time alerts to the entire astronomical community. Gaia should detected about 6000 supernovae, 1000 microlensing events and many other interesting types of transients. Thanks to its on-board low-dispersion spectrograph the classification of transients will be robust, assuring low false-alert rate. We describe the operation of the Photometric Science Alerts system, outline the scientific possibilities and conclude with an invitation to collaborate in the ground-based follow-up Gaia alerts during the early months of the mission when the outcome of the alerting pipeline needs to be verified.

Wyrzykowski, Lukasz; Blogorodnova, Nadejda; Koposov, Sergey; Burgon, Ross



Photometrics at Sandia National Laboratories  

Microsoft Academic Search

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.

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



Photometrics at Sandia National Laboratories  

SciTech Connect

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.

McWilliams, J.Y.; Hill, R.A.; Hughes, R.L. (eds.)



Photometric modeling of Saturn's rings  

Microsoft Academic Search

The scattering properties of particulate rings with volume filling factors in the interval D=0.001–0.3 are studied, with photometric Monte Carlo ray tracing simulations combining the advantages of direct (photons followed from the source) and indirect methods (brightness as seen from the observing direction). Besides vertically homogeneous models, ranging from monolayers to classical many-particle thick rings, particle distributions obtained from dynamical

Heikki Salo; Raine Karjalainen



Photometric Variability in the FSVS  

Microsoft Academic Search

The Faint Sky Variability Survey (FSVS) is aimed at nding pho- tometric and\\/or astrometric variable objects between 16th and 24th mag on time-scales between tens of minutes and years with photometric precisions ranging from 3 millimag to 0.2 mag. An area of 23 deg2, located at mid and high Galactic latitudes, was covered using the Wide Field Camera (WFC) on

L. Morales-Rueda; P. J. Groot; T. Augusteijn; G. Nelemans; P. M. Vreeswijk; E. J. M. van den Besselaar


Photometric analysis of Abell 1689  

NASA Astrophysics Data System (ADS)

We carried out a photometric analysis of a sample of early-type galaxies in Abell~1689 at z = 0.183, using HST/ACS archive images in the rest-frame V band. We performed a two-dimensional photometric decomposition of each galaxy surface-brightness distribution using the GASP2D fitting algorithm (Méndez-Abreu et al. 2008). We adopted both a Sérsic and de Vaucouleurs law. S0 galaxies were analysed also taking into account a disc component described by an exponential law. The derived photometric parameters, together with the ones previously obtained with the curve of growth method (Houghton et al. 2012), will be used to analyse the Fundamental Plane of Abell 1689 and quantify how it is affected by the use of different decomposition techniques (Dalla Bontà et al. 2013, in preparation). The stellar velocity dispersions of the sample galaxies were derived by using GEMINI-N/GMOS and VLT/FLAMES (D'Eugenio et al. 2013) spectroscopic data.

Dalla Bontà, Elena; Davies, Roger L.; Houghton, Ryan C. W.; D'Eugenio, Francesco; Corsini, Enrico M.; Méndez-Abreu, Jairo



A Titration Technique for Demonstrating a Magma Replenishment Model.  

ERIC Educational Resources Information Center

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)

Hodder, A. P. W.



Microscope Titration and Extraction of DNA from Liver.  

ERIC Educational Resources Information Center

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)

Mayo, Lois T.; And Others




PubMed Central

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

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



Potentiometric and coulometric titration of 2-thiobarbituric acid.  


A new method for the determination of 2-thiobarbituric acid, using its reaction with iodine in an alkaline medium is presented. In the volumetric titration with potentiometric end-point detection, the determinability range is 10-400 micromol (1.4-58 mg). In coulometric titration using the biamperometric end-point detection, 0.1-20 micromol (1.4 x 10(-2)-2.9 mg) of 2-thiobarbituric acid was successfully determined. PMID:18966286

Ciesielski, W; Kowalska, J; Zakrzewski, R



Potentiometric and Coulometric Titration of 6Propyl2Thiouracil  

Microsoft Academic Search

A method for the determination of 6-propyl-2-thiouracil involving its reaction with iodine in an alkaline medium is presented. In volumetric titration with potentiometric end-point detection, the range of determination is 125-500 mmol (21-85 mg). In coulometric titration using biamperometric end-point detection, 0.5-5.0mmol (0.085-0.85 mg) of 6-propyl-2-thiouracil was successfully determined. The RSD in all applied techniques was < 1%. The methods

Witold Ciesielski; Robert Zakrzewski



Potentiometric and coulometric titration of 2-thiobarbituric acid  

Microsoft Academic Search

A new method for the determination of 2-thiobarbituric acid, using its reaction with iodine in an alkaline medium is presented. In the volumetric titration with potentiometric end-point detection, the determinability range is 10–400 ?mol (1.4–58 mg). In coulometric titration using the biamperometric end-point detection, 0.1–20 ?mol (1.4 × 10?2?2.9 mg) of 2-thiobarbituric acid was successfully determined.

Witold Ciesielski; Joanna Kowalska; Robert Zakrzewski



High frequency titration of amines in nonaqueous solutions  

E-print Network

HIGH FREQUENCY TITRATION OF A%INES IN NONAQUEOUS SOLUTIONS A Thesis William Byron Witmer Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE January 1958 Major Subject: Chemistry HIGH FREQUENCY TITRATION OF ABIINES IN NONAQUEOUS SOLUTIONS A Thesis William Byron Witmer Approved as to style and content by: hairman of ommit ead of Department or Student Advisor January 1958...

Witmer, William Byron



Determination of the drug content of pharmaceuticals containing phenothiazine compounds by triangle programmed flow titration  

Microsoft Academic Search

A flow-through triangle programmed coulometric titration technique is worked out for the determination of phenothiazine compounds. The oxidation reaction of phenothiazines with hypobromite ion served as titration reaction. A biamperometric detector cell has been used for following the titration process. The titration technique has been used for the determination of the drug content (average and individual) of chlorpromazine, promethazine, diethazine

Zsófia Fehér; Ilona Kolbe; Ern? Pungor



Sloan Digital Sky Survey Photometric Calibration Revisited  

SciTech Connect

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.

Marriner, John; /Fermilab



A blind test of photometric redshift prediction  

E-print Network

Results of a blind test of photometric redshift predictions against spectroscopic galaxy redshifts obtained in the Hubble Deep Field with the Keck Telescope are presented. The best photometric redshift schemes predict spectroscopic redshifts with a redshift accuracy of |Delta-z|<0.1 for more than 68 percent of sources and with |Delta-z|<0.3 for 100 percent, when single-feature spectroscopic redshifts are removed from consideration. This test shows that photometric redshift schemes work well at least when the photometric data are of high quality and when the sources are at moderate redshifts.

David W. Hogg; Judith G. Cohen; Roger Blandford; Stephen D. J. Gwyn; F. D. A. Hartwick; B. Mobasher; Paula Mazzei; Marcin Sawicki; Huan Lin; H. K. C. Yee; Andrew J. Connolly; Robert J. Brunner; Istvan Csabai; Mark Dickinson; Mark U. SubbaRao; Alexander S. Szalay; Alberto Fernandez-Soto; Kenneth M. Lanzetta; Amos Yahil



Complexometric determination of metal ions by microscopic diffusional titration.  


Acid/base titrations of pico- and femtoliter microsamples have been performed previously using a diffusional microburet (DMB) for reagent delivery in a simple droplet-heptane system (Gratzl, M.; Yi, C. Anal. Chem. 1993, 65, 2085-2088). The lowest delivery rate achieved with a DMB was about 6 fmol/s, which would correspond to about a 1 microL/year volumetric flow rate with a hypothetical equivalent mechanical delivery scheme (Yi, C.; Gratzl, M. Anal. Chem. 1994, 66, 1976-1982). In this work, the feasibility of complexometric titrations in microscopic samples is explored. Stability of pH in the microdroplets required for different determinations and the effects of DMB shank geometry on titration characteristics are also studied. Diffusional microtitrations of Fe(III), Zn(II), and Cu(II) have been performed with EDTA. Xylenol orange and Eriochrome Black T provide clear color changes at the end point of the respective titrations, despite the microscopic size of the samples (between 16 and 1570 pL, corresponding to diameters between 30 and 144 microns). Random errors of the determinations relative to full scale were 6.6% for Fe(III), 5.8% for Cu(II), and 7.9% for Zn(II). The pH required for EDTA titrations of the individual metal ions stays stable in the acidic range. This makes the microscopic titration of a number of metal ions, such as Fe(III), Fe(II), Cu(II), and Pb(II), feasible in a simple droplet-heptane system without any modification. With a higher density of strongly alkaline buffer droplets (about 100 droplets/mm2) sprayed on the bottom of the Petri dish, or by flushing N2 above the heptane, the microscopic samples can also be kept alkaline despite ambient CO2 present. In this way, Zn(II) can also be titrated in microdroplets, requiring a pH around 10. This work renders it possible to perform a variety of complexometric titrations and other chemical manipulations in microdroplets even if they need to be kept alkaline. Similar titrations in single biological cells to assess intracellular buffer capacities of different metal ions, such as Ca(II) and Mg(II), are underway. PMID:8815747

Yi, C; Huang, D; Gratzl, M



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

NASA Technical Reports Server (NTRS)

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.

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



Potentiometric titration and equivalent weight of humic acid  

USGS Publications Warehouse

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.

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



A new approach to flow-batch titration. A monosegmented flow titrator with coulometric reagent generation and potentiometric or biamperometric detection  

Microsoft Academic Search

Monosegmented flow analysis (MSFA) has been used as a flow-batch system to produce a simple, robust, and mechanized titrator\\u000a that enables true titrations to be performed without the use of standards. This paper also introduces the use of coulometry\\u000a with monosegmented titration by proposing a versatile flow cell. Coulometric generation of the titrand is attractive for titrations\\u000a performed in monosegmented

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



Studies of cellulose surfaces by titration and ESCA  

NASA Astrophysics Data System (ADS)

The surface properties of unbleached kraft pulp fibers of varying lignin content prepared by digestion with different amounts of excess alkali have been investigated using polyelectrolyte titration, potentiometric titration and ESCA. The surfaces contain two different acidic groups that dissociate completely above pH 7.5, one with pK ? 3.6 and one with pK ? 5.7. The amount of the latter group correlates directly with the amount of lignin in the pulp. The ESCA analysis indicates that the relative amount of carboxylic groups and alkyl carbon in the surface decreases as the lignin content decreases and also that material with high alkyl carbon content is enriched in the outermost surface of the cellulose. Thus, a combination of ESCA analysis and high-precision titrations is able to yield a very detailed picture of the effect of digestion conditions on surface properties of cellulose fibers of direct relevance to paper properties.

Stenius, Per; Laine, Janne



Coulometric titration of D(+)-glucose using its enzymatic oxidation.  


A definitive method is described for the indirect assay of milligram quantities of D(+)-glucose by coulometric titration. D(+)-Glucose was aerobically oxidized by glucose oxidase in an acetate buffer solution (pH 5.1). Subsequently, the enzymatically formed hydrogen peroxide was titrated coulometrically with electrogenerated hypobromite in sodium bromide-sodium tetraborate medium of pH 8.6, with biamperometric end-point detection. Parameters affecting the enzymatically catalyzed oxidation and coulometric titration were evaluated. The optimized conditions for the oxidation of up to 20 mg of D(+)-glucose include the addition of 4500 U of glucose oxidase and stirring over a 10-min interval at 25 degrees C. Under proposed conditions, the assay values of several commercial D(+)-glucose reagents were somewhat lower than the guaranteed minimum values, with RSDs (n = 5) of 0.071 - 0.106%. PMID:11990540

Tanaka, T; Shutto, E; Mizoguchi, T; Fukushima, K



Determination of uranium by direct titration with dipicolinic acid  

SciTech Connect

Direct titration of uranium with dipicolinic acid, in the presence of Arsenazo I, is a simple, precise, and accurate method for uranium determination. The method is particularly attractive because it can be totally automated. Detecting the end point (color change from blue to pink) depends on the concentration range. For the Micro Method (1 to 20 ppM U in the solution titrated), the gradual color change is monitored spectrophotometrically. For the Macro Method (20 to 300 ppM), the end point is determined either visually or spectrophotometrically. The spectrophotometric end point is computed by fitting the titration curve. The relative standard deviation is +-1 to 3% for the Micro Method and +-0.3% for the Macro Method.

Baumann, E.W.



Potentiometric and coulometric titration of 6-propyl-2-thiouracil.  


A method for the determination of 6-propyl-2-thiouracil involving its reaction with iodine in an alkaline medium is presented. In volumetric titration with potentiometric end-point detection, the range of determination is 125-500 mumol (21-85 mg). In coulometric titration using biamperometric end-point detection, 0.5-5.0 mumol (0.085-0.85 mg) of 6-propyl-2-thiouracil was successfully determined. The RSD in all applied techniques was < 1%. The methods developed were applied to the determination of 6-propyl-2-thiouracil in tablets. PMID:9246819

Ciesielski, W; Zakrzewski, R



Big MACS: Accurate photometric calibration  

NASA Astrophysics Data System (ADS)

Big MACS is a Python program that estimates an accurate photometric calibration from only an input catalog of stellar magnitudes and filter transmission functions. The user does not have to measure color terms which can be difficult to characterize. Supplied with filter transmission functions, Big MACS synthesizes an expected stellar locus for your data and then simultaneously solves for all unknown zeropoints when fitting to the instrumental locus. The code uses a spectroscopic model for the SDSS stellar locus in color-color space and filter functions to compute expected locus. The stellar locus model is corrected for Milky Way reddening. If SDSS or 2MASS photometry is available for stars in field, Big MACS can yield a highly accurate absolute calibration.

Kelly, P. L.; von der Linden, A.; Applegate, D.; Allen, M.; Allen, S. W.; Burchat, P. R.; Burke, D. L.; Ebeling, H.; Capak, P.; Czoske, O.; Donovan, D.; Mantz, A.; Morris, R. G.



A case of atypical tardive seizure activity during an initial ECT titration series.  


Electroconvulsive therapy (ECT) has been used in this country for more than 70 years, is still the most effective treatment in all of psychiatry, and is considered a very safe procedure to have under general anesthesia. Although most patients tolerate this procedure very well without complications, prolonged and/or tardive seizures or even status epilepticus can develop, which is a rare but serious complication of ECT. Tardive seizures are typically associated with electroencephalographic evidence of ictal activity and motor manifestations of the tonic-clonic activity. Whereas there are instances of nonconvulsive status epilepticus after ECT, this is the first report of a patient developing autonomic and motor manifestations of a tardive seizure without electroencephalographic evidence of seizure activity during the initial titration series to establish seizure threshold for a course of ECT. PMID:23845940

Thisayakorn, Paul; Karim, Yasser; Yamada, Thoru; McCormick, Laurie M



Back titration with mercuric nitrate in alkaline medium  

Microsoft Academic Search

Small amounts of bismuth in the order of 100 µg up to ~ 25 mg were potentiometrically determined by back titration with mercuric nitrate in alkaline media. The method gives highly accurate results and is further successfully applied for analysis of pairs of bismuth together with one of the cations of calcium, copper, cadmium, zinc, manganese, nickel, lead, aluminium and

H. Khalifa; A. Soliman



Back titration with mercuric nitrate in alkaline medium  

Microsoft Academic Search

A rapid, reliable and accurate method for the determination of trivalent chromium, based on back titrating excess EDTA solutions in the presence of chromium versenate, with mercuric nitrate in alkaline media is given. By its aid amounts of chromium in the order of 50 micro- to 15 milligrams can be determined with fair accuracy. The method is applied for analysis

H. Khalifa; M. M. Khater



Coulometric Titration of Free Cyanide with Electrogenerated Hypobromite  

Microsoft Academic Search

A rapid and sensitive method is described for the direct determination of cyanide by coulometric titration with electrogenerated hypobromite. A biamperometric end point was utilized. From 0.498 – 9.980 ueq of cyanide were analyzed with an average error of 0.36% and an average standard deviation of 0.045.

R. A. Gibbs; R. J. Palma Sr



RESEARCH Open Access Continuous positive airway pressure titration in  

E-print Network

RESEARCH Open Access Continuous positive airway pressure titration in infants with severe upper airway obstruction or bronchopulmonary dysplasia Sonia Khirani1,2 , Adriana Ramirez2,3 , Sabrina Aloui2 airway obstruction (UAO) or bronchopulmonary dysplasia (BPD). Methods: The breathing pattern

Paris-Sud XI, Université de


LABORATORY EXPERIMENT 4 Alkalimetric Titration of an Acid Mixture  

E-print Network

LABORATORY EXPERIMENT 4 Alkalimetric Titration of an Acid Mixture In this experiment the quantitative composition of a solution, which is a mixture of a monoprotic strong acid (HCl) and a weaker triprotic acid (H3PO4) will be determined by pH- potentiometric methods. This experiment will introduce you

Nazarenko, Alexander


SUBVISIBLE RETINAL LASER THERAPY Titration Algorithm and Tissue Response  

E-print Network

SUBVISIBLE RETINAL LASER THERAPY Titration Algorithm and Tissue Response DANIEL LAVINSKY, MD, PHD,* DANIEL PALANKER, PHD* Purpose: Laser therapy for diabetic macular edema and other retinal diseases has of tissue effect. The algorithm adjusts both power and pulse duration to vary the expected level of thermal

Palanker, Daniel


A modified function of the formula of double iodometric titration  

Microsoft Academic Search

Double iodometric titration is the most useful method to determine oxygen content of high Tc superconductors. Its traditional calculating formula is not accurate enough, and a new calculating formula has just been put forward. To understand which relationship of the traditional formula depends on the new one is an important problem. On studying the new formula, we find a modified

Wu Ming Chen; J. Chen; X. Jin



Selective titrations of metal ions in the micromolar range  

Microsoft Academic Search

Summary An outline is given of the factors governing the complexometric titration of metal ions at low concentration. Apart from the limit of determination, special attention has been given to the selectivity of the determinations. The influence of the chemical reaction and of the method of indication has been discussed.

G. den Boef



Direct complexometric titration of thorium with versene using SPADNS  

Microsoft Academic Search

The existing volumetric methods for the determination of thorium are indirect and unsatisfactory. A direct titrimetric method for the estimation of thorium has been developed which involves the adjustment ofph, addition of 1 ml. of 0.02% SPADNS indicator, dilution to volume and titration with versene. It is based on the fact that thorium forms a coloured complex with SPADNS and

Gurupada Banerjee



Successive determination of praseodymium and ytterbium by coulometric complexometric titration  

SciTech Connect

A method is described for the successive coulometric complexometric titration of microgram levels of light and heavy rare earth elements. The total amount of light and heavy rare earth elements is titrated by electrogenerating titrant EDTA on the mercury pool as a cathode. Then, the mercury pool is switched as an anode, electrogenerating Hg/sup 2 +/, and is used to titrate EDTA which is displaced from its light rare earth elements complex by malic acid that has been added prior to the electrogenerating Hg/sup 2 +/. The heavy rare earth elements can be determined from the total rare earth elements minus the result of displacement titration of EDTA which is equivalent to the light rare earth elements. A 10-30 sample of light and heavy rare earth elements (Pr and Yb, La and Lu, Nd and Tm) can be determined successively. Errors and standard deviation are not more than 2.5% and 0.20, respectively. 2 tables, 5 figures.

Chun-Nian, S.; Jing-Ci, L.; Qi-Dao, N.; Mou-Sen, C.



Automatic Titrators in the Analytical and Physical Chemistry Laboratories  

Microsoft Academic Search

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

Kathryn R. Williams



Investigation of the absorption principle involved in the analyses and titrations performed in high frequency fields  

E-print Network

s e e e e ~ e e 58 Xi Contour Data for Lho Titration of ~roohlorio and Ditrie keide with 804%un F jll'oxide, ~ ~ ~ o i i ~ ~ ~ i 15 XI, Titration of Spdroohlorio kaid with Sodium Dpiroxido ~ i ~ 15 III ~ Titration of Sitrio koid with Sodiun... Epdronide e ~ e ~ i i XV XVi Titration of a Mixture of Hydroohiorie and Sitrio koide ~ e 18 VN Contour Data for the Titration of Sulphurie an4 keotie koide with 804iun Bgdronide ~ i e e ~ s + s e ~ s s ~ Sl VX+ Titration of Sulphnrie kaid with Sodiun...

Griffin, James Hilton



Photometric Studies of GEO Debris  

NASA Technical Reports Server (NTRS)

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 the B-R color is a true measure of the surface of the debris piece facing the telescopes for that observation. Any change in color reflects a real change in the debris surface.

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



Estimating the Redshift Distribution of Photometric Galaxy Samples II. Applications and Tests of a New Method  

E-print Network

In Lima et al. 2008 we presented a new method for estimating the redshift distribution, N(z), of a photometric galaxy sample, using photometric observables and weighted sampling from a spectroscopic subsample of the data. In this paper, we extend this method and explore various applications of it, using both simulations of and real data from the SDSS. In addition to estimating the redshift distribution for an entire sample, the weighting method enables accurate estimates of the redshift probability distribution, p(z), for each galaxy in a photometric sample. Use of p(z) in cosmological analyses can substantially reduce biases associated with traditional photometric redshifts, in which a single redshift estimate is associated with each galaxy. The weighting procedure also naturally indicates which galaxies in the photometric sample are expected to have accurate redshift estimates, namely those that lie in regions of photometric-observable space that are well sampled by the spectroscopic subsample. In addition to providing a method that has some advantages over standard photo-z estimates, the weights method can also be used in conjunction with photo-z estimates, e.g., by providing improved estimation of N(z) via deconvolution of N(photo-z) and improved estimates of photo-z scatter and bias. We present a publicly available p(z) catalog for ~78 million SDSS DR7 galaxies.

Carlos E. Cunha; Marcos Lima; Hiroaki Oyaizu; Joshua Frieman; Huan Lin



Photometric Study of Uranian Satellites  

NASA Technical Reports Server (NTRS)

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.

Kesten, Philip R.



Photometric Modeling of Saturn's Rings  

NASA Astrophysics Data System (ADS)

The brightness of Saturn's rings has been measured using a number of instruments on Voyager and Cassini as well as with HST. Not all of the observed characteristics of the rings have been adequately explained. Some quantities are poorly known, such as particle albedos (A), the volume filling factor (D) of the rings and ring particle scattering properties. Many previous ring photometric models have fallen into two camps: those assuming the rings to be a monolayer of particles and those assuming particles are widely spaced (D=0). Here we will present results of modeling ring brightness using the Monte Carlo photometry code of Salo and Karjalainen (2003, Icarus 164, 428). The code allows modeling of a 3D layer of ring particles with an arbitrary D and a choice of ring particle scattering phase functions. We will present preliminary ring brightness results using a variety of D, A and scattering phase function for Cassini viewing geometries. We will discuss the results of these models in the context of understanding realistic ring particle properties. This work is supported by a Graduate Student Researchers Program Fellowship from NASA Headquarters, the Cassini project, and UC's Institute of Geophysics and Planetary Physics.

Chambers, Lindsey S.; Cuzzi, J. N.; Salo, H.



The Asiago Database on Photometric Systems (ADPS) and the Design of the GAIA Photometric System  

NASA Astrophysics Data System (ADS)

The Asiago Database on Photometric Systems (ADPS) is a compilation of basic information and reference data on 201 photometric systems (both ground-based and space-born), available in book format (Moro and Munari, 2000) and electronically ( It is a relevant source of information to address the legacy of existing photometric systems to the one being designed for the GAIA mission. Its use in such a context and the planned developments are briefly discussed.

Fiorucci, Massimo; Munari, Ulisse


A New Photometric Look at M51  

E-print Network

A new technique is used to derive the extinction and age of populations in the interacting galaxies NGC5194 & NGC5195 from high S/N multicolor photometric data. A new evolutionary scenario of the interaction is proposed.

Vladas Vansevicius



Shape from shading through photometric motion  

Microsoft Academic Search

We present a new shape from shading algorithm, extending to the single-input case, a recently introduced approach to the photometric\\u000a motion process. As proposed by Pentland, photometric motion is based on the intensity variation, due to the motion, at a given\\u000a point on a rotating surface. Recently, an alternative formulation has also appeared, based on the intensity change at a

João L. Fernandes; José R. A. Torreão




Microsoft Academic Search

The problem of large deviation of determination of solanesol by coulometric titration when using direct titration technique and double Pt electrodes amperometric method indicating the end-point has been resolved. In titration process, solanesol, an electroinactive species, can be adsorbed on the surfaces of Pt electrodes and inhibit electrode reactions of Br and Br2. Therefore, when titration reaches the end-point, the

Ge Zhao; Jianying Qu; Meng Liu; Kuaizhi Liu; Zuliang Du



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


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. PMID:15708666

Abramovi?, Biljana F; Guzsvány, Valéria J; Gaál, Ferenc F



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

ERIC Educational Resources Information Center

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…

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




Microsoft Academic Search

A complexometric titration method for iron and nickel is described. The ; iron is masked with pyrophosphate, and the nickel is titrated directly with ; (ethylenediamine)tetraacetic acid (EDTA) in the presence of murexide up to the ; violot color change. The IF 620 filter is used. The iron is titrated indirectly. ; An excess of EDTA is added, which destroys



?- d-Glucosidase reaction kinetics from isothermal titration microcalorimetry  

Microsoft Academic Search

The cellobiase activities of nine thermal stable mutants of Thermobifida fusca BglC were assayed by isothermal titration microcalorimetry (ITC). The mutations were previously generated using random mutagenesis and identified by high-temperature screening as imparting improved thermal stability to the ?-d-glucosidase enzyme. Analysis of the substrate–saturation curves obtained by ITC for the wild-type enzyme and the nine thermally stabilized mutants revealed

Tina Jeoh; John O. Baker; Mursheda K. Ali; Michael E. Himmel; William S. Adney



Quantitative estimation of benzylisoquinoline derivatives by coulometric titration  

Microsoft Academic Search

A method for estimating papaverine HCl and drotaverine HCl by coulometric titration with biamperometric indication of the\\u000a end point was developed. The stoichiometric coefficients of the reactions of papaverine and drotaverine with electrogenerated\\u000a chlorine were determined. Microgram quantities of agents in substance and therapeutic forms were estimated with a relative\\u000a standard deviation (RSD) of 0.01–0.03.

G. K. Ziyatdinova; A. I. Samigullin; S. G. Abdullina; G. K. Budnikov



Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN  

E-print Network

Carboxylic Acid Unknowns and Titration 90 CARBOXYLIC ACID UNKNOWN A. Solubility Tests: Water, NaHCO3, and NaOH Test the solubility of your acid first in neutral water, in NaOH/H2O, and in NaHCO3 to 30 drops. Swirl/mix well. Use of small stir bar helps. · Water Test: Only acids with small numbers

Jasperse, Craig P.


Potentiometric titration of gold in ores with potassium iodide  

Microsoft Academic Search

A direct potentiometric titration method for the determination of gold in ores and alloys is described. It is based on the reduction of Au(III) with iodide ions yielding accurate and reproducible results. Detection limit and sensitivity were 0.06 and 0.032 mg\\/l Au, respectively. The linear response range was between 0.1 and 120 mg\\/l Au. The method can be used for

L. C. Robles; C. Garcia-Olalla; A. J. Aller



Iodometric titration of copper-oxide superconductors and Tokura's Rule  

Microsoft Academic Search

Iodometric titration measurements, which are often interpreted as obtaining the excess valence on Cu atoms in Y(LayBa1-y)2Cu3Ox, are reinterpreted as determining concentrations of 'neutral' or hypocharged oxygen instead. Tokura's Rule, an empirical relationship between the critical oxygen content xc and the critical La content yc at the onset of superconductivity, is derived on the basis of a hypocharged-oxygen model.

H. A. Blackstead; D. B. Pulling; J. D. Dow



Iodometric titration of copper-oxide superconductors and Tokura's Rule  

NASA Astrophysics Data System (ADS)

Iodometric titration measurements, which are often interpreted as obtaining the excess valence on Cu atoms in Y(La yBa 1- y) 2Cu 3O x, are reinterpreted as determining concentrations of “neutral” or hypocharged oxygen instead. Tokura's Rule, an empirical relationship between the critical oxygen content xc and the critical La content yc at the onset of superconductivity, is derived on the basis of a hypocharged-oxygen model.

Blackstead, Howard A.; Dow, John D.; Pulling, David B.



Iodometric titration of copper-oxide superconductors and Tokura's rule  

Microsoft Academic Search

Iodometric titration measurements, which are often interpreted as obtaining the excess valence on Cu atoms in Y(LayBa1?y)2Cu3Ox, are reinterpreted as determining concentrations of “neutral” or hypocharged oxygen instead. Tokura's Rule, an empirical relationship between the critical oxygen content xc and the critical La content yc at the onset of superconductivity, is derived on the basis of a hypocharged-oxygen model.

Howard A. Blackstead; John D. Dow; David B. Pulling



Hydroperoxide titration by DSC in thermally oxidized polypropylene  

Microsoft Academic Search

Unstabilized polypropylene (PP) films and stabilized PP fibres were thermally oxidized at 80°C under high oxygen pressure (5.0MPa). Their oxidation was monitored by infrared (IR) spectroscopy, iodometric titration and modulated differential scanning calorimetry (MDSC). This latter technique allows separation of the thermograms into two parts: a reversing signal containing the major part of the melting endotherm and a non-reversing exothermal

E. Richaud; F. Farcas; B. Fayolle; L. Audouin; J. Verdu



Determination of fluorine in glass crystallite using complexometric back titration  

Microsoft Academic Search

color change at the eqivalence point. To determine 0.4-2.0 mg of fluorine in organic compounds it was proposed in [3] to use complexometric titration using methylthymol blue indicator, of the excess of a lanthanum salt used to precipitate the fluorine ions. However, Murase et al. [4] felt that this method was not very suitable for determining 0.4-100 mg of fluorine

T. I. Danilevich; V. V. Abramov



A high frequency titration of indium with benzenephosphinic acid  

E-print Network

. %~ Jensen for his eid on this work, Tba Sargent-Jensen High Frequency Titrator was used to determine the amount of indium present in a chloride solution. The addition of benzenephosphinic acid, which precipitated the indium as indium benzenephosphinate..., caused certain loading variations on the oscillator. Complexes of indium in chloride solution were responsible for producing three stoichiometric breaks in the loading curve. Calculations based on the average of these breaks measured at least 98. 65...

Keilt, Francis Xavier



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


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. PMID:22561639

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



Depression May Reduce Adherence during CPAP Titration Trial  

PubMed Central

Study Objectives: Depression is a risk factor for medication non-compliance. We aimed to identify if depression is associated with poorer adherence during home-based autotitrating continuous positive airway pressure (autoPAP) titration. Design: Mixed retrospective-observational study. Setting: Academic center. Participants: Two-hundred forty continuous positive airway pressure-naïve obstructive sleep apnea (OSA) patients. Measurements: Patients underwent approximately 1 week of home-based autoPAP titration with adherence data downloaded from the device. Electronic hospital records were reviewed in a consecutive manner for inclusion. Three areas of potential predictors were examined: (i) demographics and clinical factors, (ii) disease severity, and (iii) device-related variables. Depression and anxiety were assessed using the Hospital Anxiety and Depression Scale (HADS). Scores on the subscales were categorized as normal or clinical diagnoses of depression (? 8) and anxiety (? 11). The primary outcome variable was the mean hours of autoPAP used per night. Results: Patients were diagnosed with OSA by either attended polysomnography (n = 73, AHI 25.5[15.1-41.5]) or unattended home oximetry (n = 167, ODI3 34.0[22.4-57.4]) and had home-based autoPAP titration over 6.2 ± 1.2 nights. Mean autoPAP use was 4.5 ± 2.4 hours per night. Multiple linear regression analysis revealed that depression and lower 95th percentile pressures significantly predicted lesser hours of autoPAP use (R2 = 0.19, p < 0.001). Significantly milder OSA in those requiring lower pressures may have confounded the relationship between 95th percentile pressure and autoPAP use. Conclusion: Depression was independently associated with poorer adherence during home-based autoPAP titration. Depression may be a potential target for clinicians and future research aimed at enhancing adherence to autoPAP therapy. Citation: Law M; Naughton M; Ho S; Roebuck T; Dabscheck E. Depression may reduce adherence during CPAP titration trial. J Clin Sleep Med 2014;10(2):163-169. PMID:24532999

Law, Mandy; Naughton, Matthew; Ho, Sally; Roebuck, Teanau; Dabscheck, Eli



Photometric Orbits of Extrasolar Planets  

NASA Astrophysics Data System (ADS)

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 & 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 at least a subset of cases.

Brown, Robert A.



The effect of photometric and geometric context on photometric and geometric lightness effects  

PubMed Central

We measured the lightness of probe tabs embedded at different orientations in various contextual images presented on a computer-controlled stereo display. Two background context planes met along a horizontal roof-like ridge. Each plane was a graphic rendering of a set of achromatic surfaces with the simulated illumination for each plane controlled independently. Photometric context was varied by changing the difference in simulated illumination intensity between the two background planes. Geometric context was varied by changing the angle between them. We parsed the data into separate photometric effects and geometric effects. For fixed geometry, varying photometric context led to linear changes in both the photometric and geometric effects. Varying geometric context did not produce a statistically reliable change in either the photometric or geometric effects. PMID:24464163

Lee, Thomas Y.; Brainard, David H.



Calibrated griz magnitudes of Tycho stars: All-sky photometric calibration using bright stars  

E-print Network

Photometric calibration to 5% accuracy is frequently needed at arbitrary celestial locations; however, existing all-sky astronomical catalogs do not reach this accuracy and time consuming photometric calibration procedures are required. I fit the Hipparcos B_T and V_T magnitudes along with the 2MASS J, H, and K magnitudes of Tycho-2 catalog-stars with stellar spectral templates. From the best fit spectral template derived for each star, I calculate the synthetic SDSS griz magnitudes and constructed an all-sky catalog of griz magnitudes for bright stars (Vcalibrated field (systematic + statistical) can be reduced to about 0.04, 0.03, 0.02, and 0.02,mag, in the g, r, i, and z-bands, respectively. Therefore, in cases for which several calibration stars can be observed in the field of view of an instrument, accurate photometric calibration is possible.

E. O. Ofek



Defining Photometric Peculiar Type Ia Supernovae  

NASA Astrophysics Data System (ADS)

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.

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



Photometric analysis of Collinder Cluster 223  

NASA Astrophysics Data System (ADS)

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.

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


Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations  

NASA Astrophysics Data System (ADS)

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 probably part of a single macromolecular scaffold. Fresh Ulva tissue appears to contain the same three functional groups but at lower concentrations, based on wet weight. The titration in natural seawater was largely dominated by the non-carbonate alkalinity of the solution and could not be robustly modeled. Results of fits with ionic strengths fixed at their experimental values indicate that the pKas of all three groups display prominent Debije-Hückel-type behavior, hence that these acid dissociation reactions involve a different mechanism than metal-proton exchange reactions on mineral surfaces, whose distribution coefficients (i.e., equilibrium constants) generally show a weak ionic strength dependence.

Ebling, A. M.; Schijf, J.



A new approach to flow-batch titration. A monosegmented flow titrator with coulometric reagent generation and potentiometric or biamperometric detection.  


Monosegmented flow analysis (MSFA) has been used as a flow-batch system to produce a simple, robust, and mechanized titrator that enables true titrations to be performed without the use of standards. This paper also introduces the use of coulometry with monosegmented titration by proposing a versatile flow cell. Coulometric generation of the titrand is attractive for titrations performed in monosegmented systems, because the reagent can be added without increasing the volume of sample injected. Also, biamperomeric and potentiometric detection of titration end-points can increase the versatility of the monosegmented titrator. The cell integrates coulometric generation of the titrand with detection of end-point by potentiometry or biamperometry. The resulting titrator is a flow-batch system in which the liquid monosegment, constrained by the interfaces of the gaseous carrier stream, plays the role of a sample of known volume to be titrated. The system has been used for determination of ascorbic acid, by coulometric generation of I2 with biamperometric detection, and for determination of Fe(II), by coulometric generation of Ce(IV) with potentiometric detection of the end-point, both in feed supplements. PMID:17036213

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



Photometric Analysis with CONCAM Sky Monitoring Data  

NASA Astrophysics Data System (ADS)

Practical data analysis techniques useful with CONtinuous CAMera (CONCAM) data are discussed. Analysis is presented of distortion near the edges of the wide CONCAM fields and how these affect the utility of data stored at Preliminary photometric analyses limiting the peak optical brightness of the optical counterparts to two gamma-ray bursts, GRB000926 and GRB001005, are presented. A preliminary photometric analysis is also given for Polaris and the variability of other bright stars. We discuss potential future scientific returns of analyzing publicly archive CONCAM data available at

Perez-Ramirez, D.; Nemiroff, R. J.; Pereira, W. E.; Rafert, J. B.; Ftaclas, C.



Interaction between bisphenol A and tannic Acid: Spectroscopic titration approach  

NASA Astrophysics Data System (ADS)

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.

Omoike, Anselm; Brandt, Benjamin



The Asiago Database on Photometric Systems (ADPS). I. Census parameters for 167 photometric systems  

NASA Astrophysics Data System (ADS)

The Asiago Database on Photometric Systems (ADPS) is a compilation of basic information and reference data on 167 optical, ultraviolet and infrared photometric systems. Thirty-four additional systems are briefly described. In compiling this census we have relied on published information only. In Paper II the photometric systems will be inter-compared, calibrated and parameterised by means of synthetic photometry using uniform criteria and the same set of input spectra and extinction laws. The ADPS is reachable at or via

Moro, D.; Munari, U.



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


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 ?l) 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. PMID:22128994

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



Acetoclastic methanogenic activity measurement by a titration bioassay.  


A titration bioassay, designed to accurately determine the activity of acetoclastic methanogens, is described that also allows evaluation of inhibition due to potential toxicants on the active biomass. The instrument is made of a pH-stat connected to an anaerobic batch reactor. Acetate is blended and mixed with anaerobic sludge in the reactor where a 1:1 N2 and CO2 mixture is sparged at the beginning of each test. As the acetoclastic methanogens consume acetate, the pH increase, and the titration unit adds acetic acid and keeps the pH constant. The rate of titrant addition is directly proportional to the methanogenic activity. A very useful feature of the system is its potential to operate for long periods (days) at constant pH and substrate (acetate) concentration. The theoretical background and principle of operation are described as well as some of the practical problems encountered with the use of the instrument. Estimation of kinetic constants for an anaerobic culture according to the Michaelis-Menten model is presented. Examples of inhibition by inorganics (NaCl) and chlorinated solvents (chloroform) are also given. PMID:11745170

Rozzi, Alberto; Castellazzi, Luca; Speece, Richard E



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


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). PMID:24393115

Bezáková, Zelmíra; Stankovi?ová, Mária



Galaxy Colors in Various Photometric Band Systems  

Microsoft Academic Search

A study is made of stellar and galaxy colors using a spectrophotometric synethesis technique. We show that use of good color response functions and a modern determination of the spectroscopic energy distribution for a alpha-Lyr gives synthetic colors in a good agreement with photometric observations to about 0.05 mag. The synthetic method then is applied to sutdy galaxy colors using

M. Fukugita; K. Shimasaku; T. Ichikawa



Dynamical and photometric investigation of comets  

NASA Technical Reports Server (NTRS)

The findings of dynamic and photometric investigations of comets are summarized, and include discussions of the comets Bennett 1970 II, Kohoutek 1973f, West 1976 VI, and periodic comets d'Arrest, Encke, and Swift Tuttle. The phenomena examined include striated and anomalous tails, tail composition and the dynamics of vaporizing dust particles, the evolution of dust jets, and split and dissipating comets.

Sekanina, Z.



System for clinical photometric stereo endoscopy  

NASA Astrophysics Data System (ADS)

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.

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



Philosophy and updating of the asteroid photometric catalogue  

NASA Technical Reports Server (NTRS)

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.

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



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


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. PMID:22428975

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



BVRI CCD photometric standards in the field of GRB 990123  

E-print Network

The CCD magnitudes in Johnson $BV$ and Cousins $RI$ photometric passbands are determined for 18 stars in the field of GRB 990123. These measurements can be used in carrying out precise CCD photometry of the optical transient of GRB 990123 using differential photometric techniques during non--photometric sky conditions. A comparison with previous photometry indicates that the present photmetry is more precise.

Nilakshi; R. K. S. Yadav; V. Mohan; A. K. Pandey; R. Sagar



Coulometric titration of organic and pharmaceutical compounds with electrogenerated gold(III)  

Microsoft Academic Search

Summary Electrogenerated AuCl4- in 0.02M HCl is used to titrate hydroquinone, ascorbic acid, phenylhydrazine, phenelzine sulphate and phenylsemicarbazide, with biamperometric end-point detection. Titration recoveries are reported and compared with results of coulometry with ceric sulphate oxidation. With less than 1 mg of sample, successive titrations can be performed in the same solution, in contrast to coulometry with ceric sulphate. Phenelzine

Marianne Chateau-Gosselin; Gary D. Christian; Gaston J. Patriarche



A simple recoverable titration method for quantitative characterization of amine-functionalized carbon nanotubes  

NASA Astrophysics Data System (ADS)

A simple recoverable titration method is described for quantitative characterization of amine functions attached to the carbon nanotubes (CNTs). This titration is a two-step method, originated from the alkaline nature of amine functions. The amount of amine functions on CNTs determinate by titration method showed a good quantitative agreement with those of thermogravimetric analysis. Interestingly, the titrated samples could be easily recovered to their original activities, with a simple base treatment. Based on simplicity and minimum spent time, this method is suggested for characterization of amine functionalities attached on carbon nanotubes as well as all graphitic nanostructures.

Moaseri, Ehsan; Baniadam, Majid; Maghrebi, Morteza; Karimi, Majid



Investigation of moisture and acids in nonaqueous mixtures by means of high frequency titration methods  

E-print Network

SY KGB, . OP HIQK liBEQ0EKY TITRATION RNSQDS 4 Thesis Vesta LalOLV TIQRee hype'oval as to style aol co@tent x'ecommealel& Heal of the Department of Chemtstrg XN3$TXGAHON OF RQXSTMR kS? VOIDS IW NOHLQEQUS MXITOHES BY lKLHS OF 'BICB FRS@3i... for the Titration of kohle and water in the 'Prosonoe of Rethgl kloohol oith Sodioa Rothjr1ato ~ ~ ~ ln Ixi Titration of phonylaootio aoQ in nethyl kloohol ~ ~ ? 15 , XXX? Titration of- koetio koid Xn koetone?? . ? ~ ??? ' ~ ~ ?, XS XV? Titratien Of Stearie keid...

Turner, Vester Lamar



Analysis of an Oxygen Bleach: A Redox Titration Lab  

NASA Astrophysics Data System (ADS)

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.

Copper, Christine L.; Koubek, Edward



Historical article: Titration studies and the structure of DNA.  


During the period of 1946-1956 ideas on the structure of the nucleic acids, especially DNA, were profoundly influenced by physico-chemical studies and, in particular, by electrometric titration studies pioneered by J. Masson Gulland and D.O. Jordan. It was eventually conclusively inferred when such studies had been sufficiently refined that: in DNA, the only hydrogen bonding that occurred was between the 1:6 amino groups of adenine and cytosine, and the -NH-CO "enolic" groups of thymine and guanine; the polynucleotide chains of DNA were not branched (or interrupted); and the internally hydrogen-bonded double-helical structure was stable both in aqueous solution and in the fibrous state. PMID:15752988

Peacocke, Arthur



Estimating Photometric Redshifts Using Support Vector Machines  

E-print Network

We present a new approach to obtaining photometric redshifts using a kernel learning technique called Support Vector Machines (SVMs). Unlike traditional spectral energy distribution fitting, this technique requires a large and representative training set. When one is available, however, it is likely to produce results that are comparable to the best obtained using template fitting and artificial neural networks. Additional photometric parameters such as morphology, size and surface brightness can be easily incorporated. The technique is demonstrated using samples of galaxies from the Sloan Digital Sky Survey Data Release 2 and the hybrid galaxy formation code GalICS. The RMS error in redshift estimation is $<0.03$ for both samples. The strengths and limitations of the technique are assessed.

Yogesh Wadadekar



Testing Photometric Methods in the Euclid Testbed  

NASA Astrophysics Data System (ADS)

The Euclid satellite will investigate the distance-redshift relationship and the evolution of cosmic structures by measuring shapes and redshifts of galaxies and clusters of galaxies. The various Euclid experiments require very accurate object photometry in order to achieve its science goals. Building upon our experience in the Dark Energy Survey data management, we have developed the Euclid Testbed which allows one to compare different methods for various data processing steps such as object detection and object photometry. Our first target is testing photometric methods that are based on measurements taken on the ensemble of single images and not on co-added images. In this contribution we present and discuss the structure of the Euclid Testbed. We introduce our own single image photometry software FitPhot, and give a detailed comparison of its accuracy with other photometric methods/software.

Kümmel, M.; Mohr, J.; Desai, S.; Henderson, R.; Koppenhoefer, J.; Paech, K.; Wetzstein, M.



The Asiago Database on Photometric Systems  

NASA Astrophysics Data System (ADS)

The Asiago Database on Photometric Systems (ADPS) is a compilation of basic information and reference data on 215 photometric systems (1386 bands in all), both from the ground and space, and covering the UV, optical and IR wavelength ranges. Paper I is available in book format \\citep{moro}. It censed only the information available from the literature. Paper II \\citep{fiorucci} presents an homogeneous derivation and calibration of band and reddening parameters for all systems with known band transmission profiles (178 systems for a total of 1251 bands). Following papers in the ADPS project will include calibration of relations sensitive to physical quantities (like Teff, lg g, [Fe/H], EB-V, etc.) and homogeneous transformation equations for all systems with known band transmission profiles. The ADPS project web page is

Munari, Ulisse; Fiorucci, Massimo


Astrophysical science with a spaceborne photometric telescope  

NASA Technical Reports Server (NTRS)

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.

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



Extending BEAMS to correlated photometric supernova data  

E-print Network

New supernova surveys such as the Dark Energy Survey, Pan-STARRS and the LSST will produce an unprecedented number of photometric supernova candidates, most with no spectroscopic follow-up. Avoiding biases in cosmological parameters due to the resulting inevitable contamination from non-Ia supernovae can be achieved with the BEAMS formalism, allowing the first fully photometric supernova cosmology studies. Here we extend BEAMS to deal with the case in which the supernovae are correlated. Doing this analytically requires evaluating 2^N terms in the posterior, where N is the number of supernova candidates. This `exponential catastrophe' is computationally unfeasible even for N of order 100. We circumvent the exponential catastrophe by marginalising numerically instead of analytically over the possible supernovae types: we augment the cosmological parameters with N discrete type parameters, tau_i, that we include in our MCMC analysis. We show that this deals well even with large correlations without a major incr...

Knights, Michelle; Varughese, Melvin; Hlozek, Renée; Kunz, Martin; Smith, Mat; Newling, James



Accurate method for determining photometric linearity.  


Accurate photometric measurements depend on the linearity of the detection system, i.e., whether the output is strictly proportional to the incident light flux. The usual method for checking linearity is to introduce filters of known absorption into the optical path. Unfortunately, the many possible errors inherent in this method make it difficult to determine linearity in this way to better than 1%. By using three polarizers in series, keeping the axes of the outer two parallel and rotating the middle polarizer, it is possible to eliminate most of these sources of error. If polarizers of the highest quality are used, photometric linearity may be determined to better than 0.1%. Accurate values for the transmission of standard filters can also be determined with this instrument. The technique is particularly useful for calibrating filters having large optical densities. An error analysis and some experimental results obtained using a three-polarizer system are given. PMID:20057523

Bennett, H E



The Sloan Digital Sky Survey Photometric Camera  

Microsoft Academic Search

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 x 2048 SITe\\/Tektronix CCDs (24 mum pixels) with an effective imaging area of 720 cm^2 and an astrometric array that uses 24 400 x 2048 CCDs with the same pixel size, which will

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



Improving LSST Photometric Calibration with Gaia Data  

E-print Network

We consider the possibility that the Gaia mission can supply data which will improve the photometric calibration of LSST. After outlining the LSST calibra- tion 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. The accuracies of the resulting standard magnitudes are found to be insufficient to satisfy LSST requirements when generated from main sequence (MS) stars, but generally adequate from DA white dwarfs (WD). 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 c...

Axelrod, Tim



Rapid, high-precision potentiometric titration of alkalinity in ocean and sediment pore waters  

Microsoft Academic Search

A system for rapid, high precision potentiometric determination of alkalinity in sea water and sediment pore water is presented. Two titration units were used: a 40 ml unit for seawater and a small volume unit for sediment pore water. Titration time was normally less than 10 minutes per sample, including sample exchange. With a 40 ml sample volume, the relative

Conny Haraldsson; Leif G. Anderson; Martin Hassellöv; Stefan Hulth; Kristina Olsson



New Insights into Chitosan-DNA Interactions Using Isothermal Titration Microcalorimetry  

E-print Network

New Insights into Chitosan-DNA Interactions Using Isothermal Titration Microcalorimetry Pei Lian Ma of deacetylation (DDA), and molecular weight (Mn) of chitosan, using isothermal titration microcalorimetry (ITC prepared by alkaline deacetylation of chitin found in the shells of crustaceans. It is a linear cationic

Buschmann, Michael


Rapid and simple determination of oxyphenbutazone in dosage forms by biamperometric titration.  


Oxyphenbutazone was determined in the presence of glacial acetic acid, hydrochloric acid, and potassium bromide by bromometric titration with biamperometric end point indication. The course of the titration was followed with double platinum electrode with 100 mV of polarizing voltage. PMID:3700329

Sebková, D; Safarík, L



Age-adapted morphine titration produces equivalent analgesia and adverse effects in younger and older patients  

E-print Network

in these patients is of importance because inadequate analgesia is likely to increase postoperative confusionAge-adapted morphine titration produces equivalent analgesia and adverse effects in younger Summary Background To determine efficacy and safety of postoperative titrated morphine in elderly patients

Paris-Sud XI, Université de


Age adapted morphine titration produces equivalent analgesia and side effects in younger and older patients  

E-print Network

period. Keywords: POSTOPERATIVE ANALGESIA, intravenous morphine titration, efficient and safe pain relief and management of postoperative pain in these patients is of importance because inadequate analgesia is likely1 Age adapted morphine titration produces equivalent analgesia and side effects in younger

Boyer, Edmond


Monitoring of an RNA Multistep Folding Pathway by Isothermal Titration Calorimetry  

E-print Network

Monitoring of an RNA Multistep Folding Pathway by Isothermal Titration Calorimetry Ce�dric Reymond Sherbrooke, Sherbrooke, Que�bec, Canada ABSTRACT Isothermal titration calorimetry was used to monitor calorimetry appears to be a method of choice for the elucidation of an RNA's folding pathway. INTRODUCTION

Perreault, Jean-Pierre


Ascorbic Acid as a Standard for Iodometric Titrations. An Analytical Experiment for General Chemistry  

Microsoft Academic Search

Ascorbic acid is suggested as the weighable compound for the standardization of iodine solutions in an analytical experiment in general chemistry. The experiment involves an iodometric titration in which iodine reacts with ascorbic acid, oxidizing it to dehydroascorbic acid. The redox titration endpoint is determined by the first iodine excess that is complexed with starch, giving a deep blue-violet color.

Cesar R. Silva; Jose A. Simoni; Carol H. Collins; Pedro L. O. Volpe



Quantitative analysis of dimethyl titanocene by iodometric titration, gas chromatography and NMR  

Microsoft Academic Search

In this study we report the use of an automated iodometric titration method and a novel gas chromatography (GC) method for the quantitative analysis of dimethyl titanocene (DMT), a key raw material in drug synthesis. Both approaches are based on the reaction of DMT in toluene or tetrahydrofuran solutions with iodine. In the case of iodometric titration, excess iodine is

Anant Vailaya; Tao Wang; Yadan Chen; Mark Huffman



Simultaneous determination of mixtures of metal ions by complexometric titration and multivariate calibration  

Microsoft Academic Search

A new complexometric titration method for the determination of mixtures of metal ions with multivariate calibration was developed. The principle of this method is described and a linear complexometric titration equation is derived. In this work, a mercury film electrode (MFE) was used as indicator electrode for potentiometric measurements, and a double junction Ag\\/AgCl electrode as reference electrode. The mixtures

Yongnian Ni; Yingliang Wu



Comparison of the Zeta Potential with the Diffuse Layer Potential from Charge Titration  

E-print Network

and the zeta potential is that the latter applies at the plane of shear, which may be up to 2-3 water diametersComparison of the Zeta Potential with the Diffuse Layer Potential from Charge Titration Phil Attard) theory is used to compare charge titration and zeta potential data for several colloids. It is found

Attard, Phil


Measurements of total carbon dioxide and alkalinity by potentiometric titration in the GEOSECS program  

Microsoft Academic Search

Approximately 6000 determinations of the alkalinity and total carbon dioxide content of seawater have now been made in the Atlantic, Pacific and Indian Oceans as part of the GEOSECS program by a computer-controlled potentiometric titration technique. The equations used to locate the equivalence points of the carbonic acid system on this titration curve were developed in 1971 but have not

Alvin L. Bradshaw; Peter G. Brewer; Deborah K. Shafer; Robert T. Williams



[Simultaneous determination of calcium and magnesium by calculative spectrophotometric complexometric titration].  


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. PMID:18330321

Liao, Li-fu; Xiao, Xi-lin; Yang, Ming-hui; Yang, Jing



Semi-supervised learning for photometric supernova classification  

NASA Astrophysics Data System (ADS)

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 per cent improvement in Type Ia purity and 13 per cent improvement in Type Ia efficiency. A web service for the supernova classification method used in this paper can be found at .

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



Dose titration of BAF312 attenuates the initial heart rate reducing effect in healthy subjects  

PubMed Central

Aim Previous studies have shown transient decreases in heart rate (HR) following administration of sphingosine 1?phosphate (S1P) receptor modulators including BAF312. This study was conducted to determine whether dose titration of BAF312 reduces or eliminates these effects. Methods Fifty?six healthy subjects were randomized 1:1:1:1 to receive BAF312 in one of two dose titration (DT) regimens (DT1 and DT2: 0.25–10?mg over 9–10?days), no titration (10?mg starting dose) or placebo. Pharmacodynamic and pharmacokinetic parameters were assessed. Results Neither DT1 nor DT2 resulted in clinically significant bradycardia or atrioventricular conduction effects. Both titration regimens showed a favourable difference on each of days 1–12 vs. the non?titration regimen on day 1 for HR effects (P < 0.0001). On day 1, the geometric mean ratio of the fraction from the previous day in minimum daily HR between DT1 and non?titration was 1.18 (95% confidence interval [CI] 1.13, 1.23) and 1.14 (95% CI 1.09, 1.18) for DT2 (both P < 0.05) with significant differences noted through to day 12. Non?titration HRs showed considerable separation from placebo throughout the study. There was no statistically significant reduction in HR vs. placebo on day?1 in either titration regimen. On days 3–7 subjects in DT1 and DT2 experienced minor reductions in HR vs. placebo (approximately 5?beats?min?1; P ? 0.0001). From days 9–12, HRs in both titration regimens were comparable with placebo. Conclusion Both titration regimens effectively attenuated the initial bradyarrhythmia observed on day 1 of treatment with BAF312 10?mg. PMID:22845008

Legangneux, Eric; Gardin, Anne; Johns, Donald



Characterization of membrane protein interactions by isothermal titration calorimetry.  


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 ?IIb?3 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 ?IIb?3 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 ?IIb?3 TM association. NMR spectroscopy confirmed ITC affinity measurements and revealed ?IIb?3 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. PMID:25178257

Situ, Alan J; Schmidt, Thomas; Mazumder, Parichita; Ulmer, Tobias S



A modified function of the formula of double iodometric titration  

NASA Astrophysics Data System (ADS)

Double iodometric titration is the most useful method to determine oxygen content of high Tc superconductors. Its traditional calculating formula is not accurate enough, and a new calculating formula has just been put forward. To understand which relationship of the traditional formula depends on the new one is an important problem. On studying the new formula, we find a modified function F relating the traditional formula to the new one, and also find that the value of F depends only on molar weight of the superconductor. For Y, Bi, and Hg systems, a group of curves of the modified function are put forward here. Since many results about average copper valence and oxygen content have been published, to correct those results one can modify them by means of the corresponding F. As a sample, we modify two published data of average copper valence and oxygen content of Y and Bi systems. After comparing the unmodified with the modified data, we find that it is necessary to modify the published data for quantitative research.

Chen, Wu Ming; Chen, J.; Jin, X.



Predicting proton titration in cationic micelle and bilayer environments  

NASA Astrophysics Data System (ADS)

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.

Morrow, Brian H.; Eike, David M.; Murch, Bruce P.; Koenig, Peter H.; Shen, Jana K.



A survey of the year 2007 literature on applications of isothermal titration calorimetry.  


Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method. PMID:18729242

Bjeli?, Sasa; Jelesarov, Ilian



Validation of histone-binding partners by peptide pull-downs and isothermal titration calorimetry.  


In order to properly describe a chromatin-binding module and understand its biology, its binding interactions need to be specifically and explicitly defined. Tremendous gains in our understanding of the function, specificity, and concerted action of chromatin-binding complexes have been made through reductionist studies of chromatin-binding modules and posttranslationally modified histone peptides. Chromatin binding proteins often discriminate between histone posttranslational modifications and sequence contexts using subtle affinity differences that appear critical to their function. Biophysical measurements are best able to discern these minute binding energy distinctions and are increasingly important as the chromatin field endeavors to detail the unique molecular recognition of myriad chromatin states. We describe the theoretical basis and advantages of various biophysical measurements of binding affinity in the chromatin field, as well as proper experimental design and procedure for peptide pull-downs and isothermal titration calorimetry (ITC). Routine use of these techniques to characterize chromatin-binding proteins has the potential to profoundly advance our view of the molecular recognition of chromatin, allowing more quantitative comparisons across the chromatin field. Ultimately, precise determination of a binding affinity not only illuminates the biochemical and structural properties of an interface, but also informs investigation of function. PMID:22910208

Malecek, Kathryn; Ruthenburg, Alexander



Asteroid taxonomic signatures from photometric phase curves  

NASA Astrophysics Data System (ADS)

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.

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



Phoebe: Albedo Map and Photometric Properties  

NASA Astrophysics Data System (ADS)

Using clear-filter images from Voyager 2 (effective wavelength 0.48 ?m), we have constructed the first-ever digital albedo map of Saturn's moon Phoebe. Most normal reflectances in this new map are between 0.07 and 0.11; the albedo histogram is largely bimodal, suggesting that the satellite is covered predominantly by two different types of surface materials. The highest albedos are confined to isolated, quasi-circular spots 40 to 100 km across, including three spots of varying albedo in a band immediately south of the equator and one especially bright spot at latitude 60°N (normal reflectance as high as 0.13, ?50% brighter than the average surface). The bright northern spot and the brightest of the southern spots occur at approximately the same longitude, an alignment that gives Phoebe its significant rotational lightcurve. The low resolution of the Voyager images does not permit interpretation of the bright spots' origin. Phoebe's global-average photometric function was determined by combining the satellite's telescopic near-opposition phase curve (S. Kruse et al.1986, Icarus68, 168-175) with absolute disk-resolved reflectances measured from the Voyager images (triaxial-ellipsoid shape assumed with radii 115, 110, and 105 km). Modeling of the telescopic observations supports the presence of a significant opposition surge, although scatter in the data does not allow unambiguous determination of the surge's exact strength. The derived photometric function is consistent with the idea that Phoebe is a C-type object—probably a primitive, captured body related to Chiron, Pholus, and the inhabitants of the Kuiper Belt. The albedo map and photometric information will aid in the planning of high-resolution Cassini images of Phoebe, which will represent our first close look at this class of primitive outer Solar-System object.

Simonelli, Damon P.; Kay, Jennifer; Adinolfi, Daniel; Veverka, Joseph; Thomas, Peter C.; Helfenstein, Paul



A photometric study of Saturn's F Ring  

NASA Technical Reports Server (NTRS)

The Saturn F Ring's radially integrated brightness has been measured over a wide range of phase angles from Voyager images; in order to model the resultant phase curve, the ring population has been divided into a dust regime and one of larger bodies, and while single scattering properties of small particles are modeled by semiempirical nonspherical/randomly oriented particles, those of large bodies are based on the photometric behavior of satellites. It is suggested that the dust in the envelope arises from micrometeoroid impacts into the large core particles, and then migrates inward.

Showalter, Mark R.; Pollack, James B.; Ockert, Maureen E.; Doyle, Laurance R.; Dalton, J. B.



Photometric functions for photoclinometry and other applications  

NASA Technical Reports Server (NTRS)

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.

Mcewen, Alfred S.



Multigrid solution of the nonlinear Poisson-Boltzmann equation and calculation of titration curves.  

PubMed Central

Although knowledge of the pKa values and charge states of individual residues is critical to understanding the role of electrostatic effects in protein structure and function, calculating these quantities is challenging because of the sensitivity of these parameters to the position and distribution of charges. Values for many different proteins which agree well with experimental results have been obtained with modified Tanford-Kirkwood theory in which the protein is modeled as a sphere (reviewed in Ref. 1); however, convergence is more difficult to achieve with finite difference methods, in which the protein is mapped onto a grid and derivatives of the potential function are calculated as differences between the values of the function at grid points (reviewed in Ref. 6). Multigrid methods, in which the size of the grid is varied from fine to coarse in several cycles, decrease computational time, increase rates of convergence, and improve agreement with experiment. Both the accuracy and computational advantage of the multigrid approach increase with grid size, because the time required to achieve a solution increases slowly with grid size. We have implemented a multigrid procedure for solving the nonlinear Poisson-Boltzmann equation, and, using lysozyme as a test case, compared calculations for several crystal forms, different refinement procedures, and different charge assignment schemes. The root mean square difference between calculated and experimental pKa values for the crystal structure which yields best agreement with experiment (1LZT) is 1.1 pH units, with the differences in calculated and experimental pK values being less than 0.6 pH units for 16 out of 21 residues. The calculated titration curves of several residues are biphasic. Images FIGURE 8 PMID:8369451

Oberoi, H; Allewell, N M



On the Physical Meaning of the Isothermal Titration Calorimetry Measurements in Calorimeters with Full Cells  

PubMed Central

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 ? H = Winj + Q (where Winj is the work necessary to carry out the titration) than in terms of ?H = 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

Grolier, Jean-Pierre E.; del Rio, Jose Manuel



Photometric Stellar Variability at the Galactic Center  

NASA Astrophysics Data System (ADS)

This study investigates the photometric variability of the stellar population at the central 10?? × 10?? of our Galaxy. 18 data sets from July 2005 to May 2012 are used, and all come from the W. M. Keck II 10 m telescope using Laser Guide Star Adaptive Optics (only one epoch uses a Natural Guide Star). Overall, the light curves of 1,949 stars are tested for variability with a photometric accuracy of ~5%. Of these, 235 stars were identified as likely variable, and 3 stars showed a periodic behavior with all of them having a period of ~3 years (the study is sensitive to periods between 1 and 4 years). All 3 stars lie outside a radius of 4?? from the central black hole and are likely to be late-type giants. The shape of the light curves is near sinusoidal which seems to make an eclipsing binary an unlikely interpretation. Long-period variable stars like Mira variables are an alternative hypothesis, however, the periods of >3 years seem uncharacteristically long.

Kelley, Michelle; Ghez, A. M.; Meyer, L.; Phifer, K. A.; REU Program, UCLA



Fast and reliable salt iodine measurement: evaluation of the WYD Iodine Checker in comparison with iodometric titration.  


Iodine deficiency persists as the leading cause of preventable brain damage and reduced intellectual capacity in the world. The most effective method for the elimination of iodine deficiency is the consumption of adequately iodized salt. Ensuring that a population receives adequately iodized salt demands careful monitoring of the salt iodine content. We evaluated the WYD Iodine Checker, a hand-held instrument that quantitatively measures the salt iodine content on the basis of a colorimetric method, and compared its performance with iodometric titration. Performance testing results indicated that the WYD Iodine Checker is a highly precise, accurate, and sensitive tool for measuring salt iodine content. It is a user-friendly instrument that is based on a simple methodology and a straightforward salt sample preparation and testing procedure. We recommend further testing to examine the field performance of the WYD Iodine Checker when measuring iodate salt samples. PMID:15214258

Dearth-Wesley, Tracy; Makhmudov, Amir; Pfeiffer, Christine M; Caldwell, Kathleen



Binding of Bovine Serum Albumin to Heparin Determined by Turbidimetric Titration and Frontal Analysis  

E-print Network

Binding of Bovine Serum Albumin to Heparin Determined by Turbidimetric Titration and Frontal analysis continuous capillary electrophoresis; BSA, bovine serum albumin; SEC, size quantita- tively. Here we demonstrate the application of capillary electrophoresis to the system of serum

Dubin, Paul D.


Rapid, high-precision potentiometric titration of alkalinity in ocean and sediment pore waters  

NASA Astrophysics Data System (ADS)

A system for rapid, high precision potentiometric determination of alkalinity in sea water and sediment pore water is presented. Two titration units were used: a 40 ml unit for seawater and a small volume unit for sediment pore water. Titration time was normally less than 10 minutes per sample, including sample exchange. With a 40 ml sample volume, the relative standard deviation of the alkalinity obtained in the laboratory was 0.05% and at sea 0.1 %. The small-volume system (0.5-1.5 ml) gave a precision of 0.07%. Five titration points, in two groups after the second equivalence point, were used to evaluate the equivalence volume. Results from equilibrium calculations and computer simulated alkalinity titrations show that it was possible to use a non-modified Gran function [( V 0 +v) ?10 ( E/Z) ] and still achieve good accuracy and precision.

Haraldsson, Conny; Anderson, Leif G.; Hassellöv, Martin; Hulth, Stefan; Olsson, Kristina



EDTA titration of bismuth(III) in ores and concentrates with biamperometric indication  

Microsoft Academic Search

A method is described for the chelatometric titration of bismuth(III) with biamperometric indication. It is applied to ores and concentrates and can also be used in presence of interfering elements (as Zr, Tl, In, Mo, Cu, Fe).

J. Vorlí?ek; P. Peták; Z. Šulcek



An isoperibol calorimeter for the investigation of biochemical kinetics and isothermal titration calorimetry  

E-print Network

Isothermal titration calorimetry is a technique used to measure the enthalpy change associated with a molecular binding interaction. From these data, the binding constant for the reaction can be determined. In the scope ...

Amadi, Ovid Charles



Effect of Molecular Acid-Base Dissociation of Salts on Conductometric Titration Curves in Acetonitrile.  

National Technical Information Service (NTIS)

The main objectives of the paper are to calculate Kf and Kd from the characteristics of conductometric titration curves at different initial concentrations of acid. Equations were derived to find, under specified conditions, Kf from the location of and Kd...

I. M. Kolthoff, M. K. Chantooni



Optimal Conditions for Masking of Sulfite Anions with Formaldehyde in Iodometric Titration of Photographic Fixing Solutions  

Microsoft Academic Search

The iodometric titration of photographic fixing solutions can be simplified by masking sulfite anions with 3% aqueous formaldehyde in a weakly acidic medium, instead of their standard masking with concentrated aqueous formaldehyde in weakly alkaline solutions.

V. N. Kiryushov; L. I. Skvortsova



Photometric Calibration of the Supernova Legacy Survey Fields  

Microsoft Academic Search

We present the photometric calibration of the Supernova Legacy Survey (SNLS). The primary goal of the SNLS is to measure the dark energy equation of state with a statistical precision of 0.05. The calibration uncertainties are currently the dominant contribution to the systematic error budget. The photometric calibration of the SNLS dataset is challenging in several aspects. First, Megacam is

Nicolas Regnault; J. Guy; M. Sullivan; J.-C. Cuillandre; P. Astier; C. Balland; S. Basa; R. G. Carlberg; D. Fouchez; D. Hardin; I. M. Hook; D. A. Howell; R. Pain; K. Perrett; C. J. Pritchet



The Photometric Performance and Calibration of WFPC2  

Microsoft Academic Search

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

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




E-print Network

A PHOTOMETRIC MODEL OF THE INCLINED F RING OF SATURN A Dissertation Presented to the Faculty RESERVED #12;A PHOTOMETRIC MODEL OF THE INCLINED F RING OF SATURN Britt Rebecca Scharringhausen, Ph.D. Cornell University 2007 Observations by Hubble Space Telescope (HST) of the rings of Saturn during

Richardson Jr., James E.



Microsoft Academic Search

The possibility of an indirect determination of Zr by an oxidation-; reduction titration of mandelic acid with KMnOâ solution was studied. As a ; preliminary step the method of titrating mandelic acid and p- bromomandelic acid ; with KMnOâ solution in an alkaline medium (l to 2N NaOH) was worked out; Nb\\/; sub 2\\/Oâ, TaâOâ, SiCâ, and WOâ did not

A. Schneer; H. Hartmann



Automatic flow titrator based on a multicommutated unsegmented flow system for alkalinity monitoring in wastewaters  

Microsoft Academic Search

A full automatic flow system based on potentiometric titration for alkalinity monitoring in wastewater treating plants is presented. Titration to an end-point of pH 5.75 partial alkalinity (PA) and then to pH 4.3 intermediate alkalinity (IA) allows to distinguish the relative buffering contributions of both bicarbonate and volatile acids in anaerobic digesters and, thus, the attainment of a IA:PA ratio

Cristina M. N. V Almeida; Rui A. S Lapa; José L. F. C Lima



Estimating the organic acid contribution to coastal seawater alkalinity by potentiometric titrations in a closed cell  

Microsoft Academic Search

This paper examines the performance of a previously reported, closed cell, potentiometric titration technique [J.M. Hernández-Ayón, S.L. Belli, A. Zirino, Anal. Chim. Acta 394 (1999) 101] for the simultaneous determination of pH, total inorganic carbon (TCO2), total alkalinity (TA), and organic alkalinity (OA) in coastal seawater samples. A novel interpretation of the titration data, as recently proposed by Hernández-Ayón et

François L. L. Muller; Bjørn Bleie




E-print Network

each titration of sulfamic acid or sample, BE SURE TO CALIBRATE THE pH METER WITH THE pH STANDARD PROVIDED. Alternate titrations of sulfamic acid and sample. Standardization of the 0.1 M NaOH Titrant. Weigh to the nearest 0.1 mg about 2.5 g of sulfamic acid and then transfer it to a 100 mL volumetric

McQuade, D. Tyler


uvby? photometric catalog toward Anticenter (Monguio+, 2013)  

NASA Astrophysics Data System (ADS)

A uvbyH? Stromgren photometric survey covering 16sq.deg in the anticenter direction was carried out using the Wide Field Camera (WFC) at the Isaac Newton Telescope (INT), with a typical seeing of 1-1.5". Data from three different observing runs (2009A, 2010B, 2011A) were used for the catalog. The calibration to the standard system was undertaken using open clusters. A main catalog of 35974 stars with all Stromgren indexes, and a more extended one with 96980 stars with partial data. The central 8sq.deg have a limiting magnitude of V=17mag while the outer region reaches V=15.5mag. Two catalogs are available, the first one with the final mean values and a second one with all the individual measurements for each star. (2 data files).

Monguio, M.; Figueras, F.; Grosbol, P.



Photometric Variability of Magnetic White Dwarfs  

NASA Astrophysics Data System (ADS)

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.

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.



Photometric Redshifts: A Comparison of Methods  

NASA Astrophysics Data System (ADS)

The advantages of being able to accurately extract red-shifts from photometric data is of great importance when wanting to complete large scale surveys of the night sky. In an exposure of minutes, rather than the hours needed for spectroscopy, we are able to gain colour data from a great number of astronomical sources at once. This is especially apparent with the advent of large format panoramic cameras such as the INT WFC, MegaCam at the Canada-France-Hawaii Telescope (CFHT) and, in the future, VISTA (Visible & Infrared Survey Telescope for Astronomy). If this data can then be used to accurately calculate the distribution of galaxies with red-shift, the large scale structure of the universe can be more readily determined.

Batcheldor, D.; Walton, N.



Estimating Photometric Redshifts Using Genetic Algorithms  

NASA Astrophysics Data System (ADS)

Photometry is used as a cheap and easy way to estimate redshifts of galaxies, which would otherwise require considerable amounts of expensive telescope time. However, the analysis of photometric redshift datasets is a task where it is sometimes difficultto achievea high classification accuracy. This work presents a custom Genetic Algorithm (GA) for mining the Hubble Deep Field North (HDF-N) datasets to achieve accurate IF-THEN classification rules. This kind of knowledge representation has the advantage of being intuitively comprehensible to the user, facilitating astronomers' interpretation of discovered knowledge. The GA is tested againstthe state of the art decision tree algorithm C5.0 [Rulequest, 2005] in two datasets, achieving better classification accuracy and simplerrule sets in both datasets.

Miles, Nicholas; Freitas, Alex; Serjeant, Stephen


Robust photometric stereo using structural light sources  

NASA Astrophysics Data System (ADS)

We propose a robust photometric stereo method by using structural arrangement of light sources. In the arrangement, light sources are positioned on a planar grid and form a set of collinear combinations. The shadow pixels are detected by adaptive thresholding. The specular highlight and diffuse pixels are distinguished according to their intensity deviations of the collinear combinations, thanks to the special arrangement of light sources. The highlight detection problem is cast as a pattern classification problem and is solved using support vector machine classifiers. Considering the possible misclassification of highlight pixels, the ?1 regularization is further employed in normal map estimation. Experimental results on both synthetic and real-world scenes verify that the proposed method can robustly recover the surface normal maps in the case of heavy specular reflection and outperforms the state-of-the-art techniques.

Han, Tian-Qi; Cheng, Yue; Shen, Hui-Liang; Du, Xin



PHOTCAL: The IRAF photometric calibration package  

NASA Technical Reports Server (NTRS)

The IRAF photmetric calibration package PHOTCAL is discussed. PHOTCAL is a set of tasks designed to derive the transformation from the instrumental photometric system to the standard photometric system, and apply the transformation to the observations. The PHOTCAL package contains tasks for: (1) creating and/or editing standard star catalogs and observations catalogs, (2) creating, checking and editing the configuration file which specifies the format of the standard star and observations catalogs and the form of the transformation equations, (3) solving the transformation equations interactively or non-iteractively using non-linear least squares fitting routines, and (4) applying the transformation to the observations. PHOTCAL standard star and observations catalogs are simple text files, whose columns are delimited by whitespace, and whose first column contains the star names. This format makes it relatively easy to interface the output of non-IRAF photometry programs as well as the output of the IRAF APPHOT and DAOPHOT photometry packages to PHOTCAL. PHOTCAL maintains a standard star catalog directory for the convenience of the user, but users can easily create their own standard star catalogs and/or define their own standard star catalog directory. Separate observations files produced by APPHOT, DAOPHOT or a user program containing data for stellar fields taken through different filters, can be combined into observations catalogs using one of the PHOTCAL preprocessor tasks. The input configuration file required by PHOTCAL is a text file, consisting of a series of instructions written by the user in a mini-language understood by the PHOTCAL parser. These instructions: (1) assign names to the input data columns in the standard star and observations catalogs, (2) assign names and initial values to the parameters to be fit, (3) define and describe how to solve the transformation equations. The mini-language approach permits great flexibility in the format of the input catalogs and the form of the transformation equations.

Davis, L. E.; Gigoux, P.



Standard Stars for the BYU ? Photometric System  

NASA Astrophysics Data System (ADS)

We present our list of primary standard stars for the BYU ? photometric system. This system is similar to the ? photometric system that is frequently used in conjunction with the intermediate band uvby system. Both systems use the difference between magnitudes measured in a wide (15-20-nm) and narrow (3-nm) bandpass centered on one of the strong Balmer lines of hydrogen to establish a temperature sensitive color index. Line indices formed in this manner are independent of atmospheric extinction and interstellar reddening. The present list of standard stars for the BYU system was established using spectroscopic observations that fully cover the region between H-? and H- ?. Color indices were established using synthetic photometry reductions to convolve ideal filter profiles with the observed spectra. Typical numbers of observations per star is in excess of 20 with some stars having been observed more than 60 times over five years. The typical error per observation for the standards is on the order of 1-3 mmag. Complete information for each star is provided in the tables for this presentation. In addition to the standard field stars, we present ? and ? observations of individual stars that are members of selected open clusters. These include the Hyades, Pleiades, Coma, and NGC 752 clusters. These stars fit the same main sequence plot as has been found for the standard field stars in the ?-? plane. Stars that exhibit varying degrees of hydrogen emission are easily noticed in an ?-? plot. We have found that candidates for emission line objects, high mass x-ray binaries, and young stellar objects are readily identified in our color-color plots. We acknowledge continued support from the BYU College of Physical and Mathematical Sciences as well as partial support from NSF Grant AST #0618209. We also thank the Dominion Astrophysical Observatory for continued allocation of robotic observing time for spectroscopy on the 1.2-m telescope.

Joner, Michael D.; Hintz, E. G.




Microsoft Academic Search

The processes for dissolution of the oxalate and complexometry to ; determine the small amounts of rare earth rapidly and accurately, were studied. ; Crystalline rare earth oxalate was precipitated and filtered. The precipitate ; was dissolved completely with EDTA in alkaline solution and the excess of EDTA in ; solution was back titrated with standard magnesium sulfate solution. By

Seizo Misumi; Tomitsugu Taketatsu



Sulfur in graphite by combustion-iodometric titration method  

SciTech Connect

The method covers the determination of sulfur in graphite in the concentration range of 1 to 200 in a l-g sample or 5 to 1000 in a 0.2-g sample. The method includes a discussion of interferences, apparatus, reagents and materials, procedure, calculations, and precision. (JMT)

Not Available



An imaging-based photometric and colorimetric measurement method for characterizing OLED panels for lighting applications  

NASA Astrophysics Data System (ADS)

The organic light-emitting diode (OLED) has demonstrated its novelty in displays and certain lighting applications. Similar to white light-emitting diode (LED) technology, it also holds the promise of saving energy. Even though the luminous efficacy values of OLED products have been steadily growing, their longevity is still not well understood. Furthermore, currently there is no industry standard for photometric and colorimetric testing, short and long term, of OLEDs. Each OLED manufacturer tests its OLED panels under different electrical and thermal conditions using different measurement methods. In this study, an imaging-based photometric and colorimetric measurement method for OLED panels was investigated. Unlike an LED that can be considered as a point source, the OLED is a large form area source. Therefore, for an area source to satisfy lighting application needs, it is important that it maintains uniform light level and color properties across the emitting surface of the panel over a long period. This study intended to develop a measurement procedure that can be used to test long-term photometric and colorimetric properties of OLED panels. The objective was to better understand how test parameters such as drive current or luminance and temperature affect the degradation rate. In addition, this study investigated whether data interpolation could allow for determination of degradation and lifetime, L70, at application conditions based on the degradation rates measured at different operating conditions.

Zhu, Yiting; Narendran, Nadarajah; Tan, Jianchuan; Mou, Xi



Photometric classification of emission line galaxies with machine-learning methods  

NASA Astrophysics Data System (ADS)

In this paper, we discuss an application of machine-learning-based methods to the identification of candidate active galactic nucleus (AGN) from optical survey data and to the automatic classification of AGNs in broad classes. We applied four different machine-learning algorithms, namely the Multi Layer Perceptron, trained, respectively, with the Conjugate Gradient, the Scaled Conjugate Gradient, the Quasi Newton learning rules and the Support Vector Machines, to tackle the problem of the classification of emission line galaxies in different classes, mainly AGNs versus non-AGNs, obtained using optical photometry in place of the diagnostics based on line intensity ratios which are classically used in the literature. Using the same photometric features, we discuss also the behaviour of the classifiers on finer AGN classification tasks, namely Seyfert I versus Seyfert II, and Seyfert versus LINER. Furthermore, we describe the algorithms employed, the samples of spectroscopically classified galaxies used to train the algorithms, the procedure followed to select the photometric parameters and the performances of our methods in terms of multiple statistical indicators. The results of the experiments show that the application of self-adaptive data mining algorithms trained on spectroscopic data sets and applied to carefully chosen photometric parameters represents a viable alternative to the classical methods that employ time-consuming spectroscopic observations.

Cavuoti, Stefano; Brescia, Massimo; D'Abrusco, Raffaele; Longo, Giuseppe; Paolillo, Maurizio



Photometric Redshifts for the SDSS Early Data Release  

E-print Network

The Early Data Release from the Sloan Digital Sky survey provides one of the largest multicolor photometric catalogs currently available to the astronomical community. In this paper we present the first application of photometric redshifts to the $\\sim 6$ million extended sources within these data (with 1.8 million sources having $r' < 21$). Utilizing a range of photometric redshift techniques, from empirical to template and hybrid techniques, we investigate the statistical and systematic uncertainties present within the redshift estimates for the EDR data. For $r'<21$ we find that the redshift estimates provide realistic redshift histograms with an rms uncertainty in the photometric redshift relation of 0.035 at $r'<18$ and rising to 0.1 at $r'<21$. We conclude by describing how these photometric redshifts and derived quantities, such as spectral type, restframe colors and absolute magnitudes, are stored within the SDSS database. We provide sample queries for searching on photometric redshifts and list the current caveats and issues that should be understood before using these photometric redshifts in statistical analyses of the SDSS galaxies.

Istvan Csabai; Tamas Budavari; Andrew J. Connolly; Alexander S. Szalay; Zsuzsanna Gyory; Narciso Benitez; Jim Annis; Jon Brinkmann; Daniel Eisenstein; Masataka Fukugita; Jim Gunn; Stephen Kent; Robert Lupton; Robert C. Nichol; Chris Stoughton



Photometric normalization of LROC WAC images  

NASA Astrophysics Data System (ADS)

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 variability of the regolith from region to region. As the fitting area increases, the accuracy of curve fitting decreases due to the larger variety of albedo, topography, and composition. Thus we have adopted an albedo-dependent photometric normalization routine. Phase curves are derived for discreet bins of preliminary normalized reflectance calculated from Clementine global mosaic in a fitting area that is composed of predominantly mare in Oceanus Procellarum. The global WAC mosaic was then corrected pixel-by-pixel according to its preliminary reflectance map with satisfactory results. We observed that the phase curves per normalized-reflectance bins become steeper as the reflectance value increases. Further filtering by using FeO, TiO2, or optical maturity [5] for parameter calculations may help elucidate the effects of surface composition and maturity on photometric properties of the surface. [1] Hapke, B.W. (1993) Theory of Reflectance and Emittance Spectroscopy, Cambridge Univ. Press. [2] Schoenberg (1925) Ada. Soc. Febb., vol. 50. [3] Hillier et al. (1999) Icarus 141, 205-225. [4] McEwen (1991) Icarus 92, 298-311. [5] Lucey et al. (2000) JGR, v105, no E8, p20377-20386.

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



Water Determination Using Karl Fischer Titration Water content needs to be determined at all stages of the manufacturing process from raw materials to  

E-print Network

by iodine in the presence of water. It is the same reaction as the iodometric titration of sulphur dioxideWater Determination Using Karl Fischer Titration Water content needs to be determined at all stages and ease of use is Karl Fischer titration. The titration is based on the oxidation of sulphur dioxide

Nazarenko, Alexander


Photometric Redshift Estimation on SDSS Data Using Random Forests  

NASA Astrophysics Data System (ADS)

Given multiband photometric data from the SDSS DR6, we estimate galaxy redshifts. We employ a Random Forest trained on color features and spectroscopic redshifts from 80,000 randomly chosen primary galaxies yielding a mapping from color to redshift such that the difference between the estimate and the spectroscopic redshift is small. Our methodology results in tight RMS scatter in the estimates limited by photometric errors. Additionally, this approach yields an error distribution that is nearly Gaussian with parameter estimates giving reliable confidence intervals unique to each galaxy photometric redshift.

Carliles, S.; Budavári, T.; Heinis, S.; Priebe, C.; Szalay, A.



Ascorbic Acid as a Standard for Iodometric Titrations. An Analytical Experiment for General Chemistry  

NASA Astrophysics Data System (ADS)

Ascorbic acid is suggested as the weighable compound for the standardization of iodine solutions in an analytical experiment in general chemistry. The experiment involves an iodometric titration in which iodine reacts with ascorbic acid, oxidizing it to dehydroascorbic acid. The redox titration endpoint is determined by the first iodine excess that is complexed with starch, giving a deep blue-violet color. The results of the titration of iodine solution using ascorbic acid as a calibration standard were compared with the results acquired by the classic method using a standardized solution of sodium thiosulfate. The standardization of the iodine solution using ascorbic acid was accurate and precise, with the advantages of saving time and avoiding mistakes due to solution preparation. The colorless ascorbic acid solution gives a very clear and sharp titration end point with starch. It was shown by thermogravimetric analysis that ascorbic acid can be dried at 393 K for 2 h without decomposition. This experiment allows general chemistry students to perform an iodometric titration during a single laboratory period, determining with precision the content of vitamin C in pharmaceutical formulations.

Silva, Cesar R.; Simoni, Jose A.; Collins, Carol H.; Volpe, Pedro L. O.



Quantitative analysis of dimethyl titanocene by iodometric titration, gas chromatography and NMR.  


In this study we report the use of an automated iodometric titration method and a novel gas chromatography (GC) method for the quantitative analysis of dimethyl titanocene (DMT), a key raw material in drug synthesis. Both approaches are based on the reaction of DMT in toluene or tetrahydrofuran solutions with iodine. In the case of iodometric titration, excess iodine is titrated with a standardized aqueous sodium thiosulfate solution to a potentiometric end-point for the determination of DMT concentration. Alternatively, GC is employed to measure the concentration of iodomethane, a product of the reaction between DMT and iodine, in order to determine the concentration of DMT in the solution. Excellent agreement between iodometric titration, GC and NMR results using several DMT samples confirms the accuracy of the two methods and strongly supports the use of either method as a replacement to the expensive NMR for quantitative DMT analysis. The relatively few sources of error associated with the two methods, their ubiquitous nature and ease of application in routine analysis make them the analytical methods of choice, among all. Both methods have been validated according to ICH requirements. The use of iodometric titration method for DMT analysis is demonstrated with a couple of applications. PMID:11377038

Vailaya, A; Wang, T; Chen, Y; Huffman, M



Psychiatric disorder does not preclude adequate continuous positive airway pressure titration.  


Obstructive sleep apnea (OSA) is a highly prevalent disorder associated with significant morbidity and multiple complications. A large proportion of patients with OSA also have a coexisting primary psychiatric disorder. The effect of psychiatric disorders on the ability to tolerate continuous positive airway pressure (CPAP) titration is not known. In this study, whether the presence of psychiatric disorders precludes the patients' ability to tolerate CPAP titration for OSA was investigated. A retrospective chart review on a sample of 284 patients who underwent sleep studies in a single-center, university-based Veterans Affairs hospital was performed. A total of 143 patients with OSA who underwent titration of CPAP therapy were identified. The prevalence of psychiatric disorders between patients who tolerated titration and those who did not tolerate it was compared using the ?² test. The percentages of patients with psychiatric disorders who tolerated and did not tolerate CPAP were 33.6% and 33.3%, respectively. No statistically significant difference between the 2 groups (?² = 0.051 with 1 degree of freedom; P = 0.82) was found. The predominantly male patient population, exclusion of mild OSA, lack of data about the level of control of the psychiatric symptoms and the sleep technicians not being blinded to the patients' psychiatric diagnoses were some of the limitations of this study. No significant difference existed in the prevalence of psychiatric disorders between patients intolerant to CPAP titration and those who tolerated CPAP for OSA. PMID:23138124

Manjunath, Skantha K; Sarva, Siva T; Yataco, Jose C; Murillo, Luis C; Avecillas, Jaime F; Freire, Amado X



Statistical criteria for the identification of protein active sites using Theoretical Microscopic Titration Curves.  


Theoretical Microscopic Titration Curves (THEMATICS) may be used to identify chemically important residues in active sites of enzymes by characteristic deviations from the normal, sigmoidal Henderson-Hasselbalch titration behavior. Clusters of such deviant residues in physical proximity constitute reliable predictors of the location of the active site. Originally the residues with deviant predicted behavior were identified by human observation of the computed titration curves. However, it is preferable to select the unusual residues by mathematically well-defined criteria, in order to reduce the chance of error, eliminate any possible biases, and substantially speed up the selection process. Here we present some simple statistical tests that constitute such selection criteria. The first derivatives of the predicted titration curves resemble distribution functions and are normalized. The moments of these first derivative functions are computed. It is shown that the third and fourth moments, measures of asymmetry and kurtosis, respectively, are good measures of the deviations from normal behavior. Results are presented for 44 different enzymes. Detailed results are given for 4 enzymes with 4 different types of chemistry: arginine kinase from Limulus polyphemus (horseshoe crab); beta-lactamase from Escherichia coli; glutamate racemase from Aquifex pyrophilus; and 3-isopropylmalate dehydrogenase from Thiobacillus ferrooxidans. The relationship between the statistical measures of nonsigmoidal behavior in the predicted titration curves and the catalytic activity of the residue is discussed. PMID:15739204

Ko, Jaeju; Murga, Leonel F; André, Pierrette; Yang, Huyuan; Ondrechen, Mary Jo; Williams, Ronald J; Agunwamba, Akochi; Budil, David E



Photometric Monitoring of Quasars with Kepler  

NASA Astrophysics Data System (ADS)

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.

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



First photometric properties of Dome C, Antarctica  

NASA Astrophysics Data System (ADS)

Here we present the first photometric extinction measurements in the visible range performed at Dome C in Antarctica, using PAIX photometer (Photometer AntarctIca eXtinction). It is made with "off the shelf" components, Audine camera at the focus of Blazhko telescope, a Meade M16 diaphragmed down to 15 cm. For an exposure time of 60 s without filter, a 10th V-magnitude star is measured with a precision of 1/100 mag. A first statistics over 16 nights in August 2007 leads to a 0.5 magnitude per air mass extinction, may be due to high altitude cirrus. This rather simple experiment shows that continuous observations can be performed at Dome C, allowing high frequency resolution on pulsation and asteroseismology studies. Light curves of one of RR Lyrae stars: SAra were established. They show the typical trend of a RRLyrae star. A recent sophisticated photometer, PAIX II, has been installed recently at Dome C during polar summer 2008, with a ST10 XME camera, automatic guiding, auto focusing and Johnson/Bessel UBVRI filter wheels.

Chadid, M.; Vernin, J.; Jeanneaux, F.; Mekarnia, D.; Trinquet, H.



A Comprehensive Photometric Investigation of 185 Eunike  

NASA Astrophysics Data System (ADS)

We have reevaluated our previous photometric data sets of 185 Eunike for oppositions in the years 2010, 2011, and 2012, respectively, and have obtained new observations in 2014 Jan. - May. For each of these four years we draw period spectra which show deep minima only near 21.8 hours and the double period near 43.6 hours, and plot lightcurves phased to near 21.8 and 43.6 hours, respectively. For observation sets in each of the four years we find the available parts of the lightcurves phased to 43.6 hours and separated by 1/2 cycle to be identical within errors of observations, and conclude that the double period is ruled out. For the new observations in the year 2014 we find best fit to a lightcurve phased to 21.812 ± 0.001 hours with amplitude 0.08 ± 0.01 magnitudes. The absolute magnitude and the opposition parameter are H = 7.45 ± 0.01, G = 0.11 ± 0.02. The V-R color index was determined to be 0.36 ± 0.03. Both the color index and G value are compatible with a low albedo asteroid. The diameter is estimated to be D = 175 ± 33 km. The lightcurve inversion analysis shows a preliminary sidereal period/pole solution at Ps = 21.80634 ± 0.00012 h and (? = 136°, ? = 4°), (? = 314°, ? = -18°), with an error estimation of ± 30 degrees.

Pilcher, Frederick; Behrend, Raoul; Bernasconi, Laurent; Franco, Lorenzo; Hills, Kevin; Martin, Axel; Ruthroff, John C.



Photometric astrometry applied to asteroids 6, 15, 43, and 624  

NASA Astrophysics Data System (ADS)

A new version of photometric astrometry is presented. This method made it possible to obtain the sense of rotation, sidereal period and pole orientation of the following asteroids: 6 Hebe, 15 Eunomia, 43 Ariadne and 624 Hektor.

Michalowski, Tadeusz


Photometric and Astrometric Calibration of the JWST Instrument Complement  

E-print Network

In preparation for James Webb Space Telescope (JWST), a set of cross calibration programs with HST and Spitzer for suitable primary photometric standards and astrometric fields were developed. NICMOS/HST and IRAC/Spitzer photometry observations of new solar analog standards in NGC 6791 and Melotte 66 were executed. These new photometric standards will provide ~ 5% photometric precision at V~19 from the near-IR to the mid-IR wavelength range for efficient on-orbit calibration and measuring of photometric stability of the JWST complement. For the astrometric calibration, a field in the LMC has been selected. This field falls within the JWST continuous viewing zone, within 5 degrees from the ecliptic poles, and has the stellar density necessary to achieve accuracies better than 1 mas with HST/ACS. These independent observations will play a key role in meeting the mission requirements and will allow a fast commissioning of the observatory.

Rosa I. Diaz-Miller



Ionophore-based ion-exchange emulsions as novel class of complexometric titration reagents.  


Complexometric titrations rely on a drastic change of the pM value at the equivalence point with a water soluble chelator forming typically 1?:?1 complexes of high stability. The available chemical toolbox of suitable chelating compounds is unfortunately limited because many promising complexing agents are not water soluble. We introduce here a novel class of complexometric titration reagents, a suspension of polymeric nanospheres whose hydrophobic core is doped with lipophilic ion-exchanger and a selective complexing agent (ionophore). The emulsified nanospheres behave on the basis of heterogeneous ion exchange equilibria where the initial counter ion of the ion-exchanger is readily displaced from the emulsion for the target ion that forms a stable complex in the nanosphere core. Two different examples are shown with Ca(2+) and Pb(2+) as target ions. The lack of protonatable groups on the calcium receptor allows one to perform Ca(2+) titration without pH control. PMID:25205536

Zhai, Jingying; Xie, Xiaojiang; Bakker, Eric



Photometric study of an eclipsing binary in Praesepe  

NASA Astrophysics Data System (ADS)

We present CCD photometric observations of an eclipsing binary in the direction of the open cluster Praesepe using the 2 m telescope at IUCAA Girawali Observatory, India. Though the system was classified as an eclipsing binary by Pepper et al., detailed investigations have been lacking. The photometric solutions using the Wilson-Devinney code suggest that it is a W-type W UMa system and, interestingly, the system parameters are similar to another contact binary system SW Lac.

Shanti Priya, Devarapalli; Sriram, Kandulapati; Vivekananda Rao, Pasagada



Titration of free hydroxyl and strained siloxane sites on silicon dioxide with fluorescent probes.  


A technique enabling the detection and quantification of low density sites on planar SiO2 surfaces is demonstrated. Fluorescent probes are used to titrate free hydroxyl and strained siloxane sites on the surface of amorphous SiO2 substrates in vacuum. The titration of free hydroxyl sites was performed to validate the method and to provide a reference for the measurement of the strained siloxane site density. Perylene derivatives with different functional groups are chemisorbed onto the surface sites, enabling in situ photoluminescence (PL) measurements of the bound fluorophores. An amine functional group is used to selectively titrate strained siloxane sites, while an alcohol group is used for the titration of free hydroxyl sites. Emission intensity was found to be nonlinear with coverage for bound fluorophore densities greater than 0.1 nm(-2), necessitating the removal of molecules from the surface into a solution to obtain accurate density measurements. For lower densities, the coverage of bound fluorophores can be estimated directly from in situ PL measurements. The measured areal densities of bound fluorophores after titrating free hydroxyl sites are in good agreement with literature values for the densities of such sites on high surface area silica. PL measurements of SiO2 surfaces titrated with an amine derivative of perylene indicate that strained siloxane sites exist for vacuum pretreatment temperatures of 300 °C and increase with increasing pretreatment temperature. Densities of strained siloxane sites on the silica surface are estimated at 0.004-0.02 nm(-2) for pretreatment temperatures of 300-700 °C, demonstrating the sensitivity of this technique. PMID:23978272

McCrate, Joseph M; Ekerdt, John G



Photometric Search of Protoplanetary Disks in Young Stellar Clusters  

NASA Astrophysics Data System (ADS)

Approximately half of the young stars with ages of about 1 million years are still embedded in its parent molecular cloud showing strong emission in the infrared region. This emission is believed to be produced in the dusty optically-thick disk surrounding the star. However, the optically-thick disk emission disappears at ages of about 30 Myr. The explanation for this is that dust grains agglomerate in larger bodies, forming planetesimals and ultimately planets, which sweep up much of the remaining gas and dust. To characterize the evolution of protoplanetary disk it is necessary to study samples of stars in the appropiate age range. However, the lack of suitable samples has been a problem to carry out such studies. In this work, one of our goals is to determine the age of various young clusters by means of UBVRI photometric observations. Once we have derived ages for the clusters in the sample, we will select the best stellar candidates whose age ranges between 3 and 10 million years. We present preliminary results of the UBVRI photometry for one of our young clusters in the sample, NGC 6823. Observations were taken at the 1.5 m at the San Pedro Martir Observatory, Universidad Nacional Autonoma de Mexico in 2009 March 27 to April 1. Data reduction was performed using IRAF standard procedures. We have obtained a color-magnitude diagram for NGC 6823 and we have compared it with the Girardi et al. (2000) isochrones in order to derive stellar ages. This work was supported by grants CONACYT 103914 and Programa de Colaboracion Academica y Cultural UNISON-UNAM U38P167.

Del Carmen, Azucena; Perez-Rendon, B.; Contreras, M. E.



Calorimetric vs. van't Hoff binding enthalpies from isothermal titration calorimetry: Ba2+-crown ether complexation.  


The 1:1 complexation reaction between Ba(2+) and 18-crown-6 ether is re-examined using isothermal titration calorimetry (ITC), with the goal of clarifying previously reported discrepancies between reaction enthalpies estimated directly (calorimetric) and indirectly, from the temperature dependence of the reaction equilibrium constant K (van't Hoff). The ITC thermograms are analyzed using three different non-linear fit models based on different assumptions about the data error: constant, proportional to the heat and proportional but correlated. The statistics of the fitting indicate a preference for the proportional error model, in agreement with expectations for the conditions of the experiment, where uncertainties in the delivered titrant volume should dominate. With attention to proper procedures for propagating statistical error in the van't Hoff analysis, the differences between Delta H(cal) and Delta H(vH) are deemed statistically significant. In addition, statistically significant differences are observed for the Delta H(cal) estimates obtained for two different sources of Ba(2+), BaCl(2) and Ba(NO(3))(2). The effects are tentatively attributed to deficiencies in the standard procedure in ITC of subtracting a blank obtained for pure titrant from the thermogram obtained for the sample. PMID:15223140

Mizoue, Laura S; Tellinghuisen, Joel



Determination of submillimolar concentration of ferrate(VI) in alkaline solutions by amperometric titration  

Microsoft Academic Search

A new amperometric titration method was developed for quantitative determination of ferrate(VI) (FeVIO4\\u000a 2?) in the 7.06×10?5?5.73×10?3 M concentration range. Chromium(III) hydroxide solution was used as the titrant. The diffusion current (Id) had a linear\\u000a relationship with the concentration of ferrate(VI) and slopes were dependent on the concentration of NaOH. The amperometric\\u000a titration could detect a lower concentration of ferrate(VI)

Dmitriy A. Golovko; Virender K. Sharma; Olga. V. Pavlova; Elena. A. Belyanovskaya; Igor. D. Golovko; Victoria. I. Suprunovich; Radek Zboril



Monitoring of an RNA Multistep Folding Pathway by Isothermal Titration Calorimetry  

PubMed Central

Abstract Isothermal titration calorimetry was used to monitor the energetic landscape of a catalytic RNA, specifically that of the hepatitis delta virus ribozyme. Using mutants that isolated various tertiary interactions, the thermodynamic parameters of several ribozyme-substrate intermediates were determined. The results shed light on the impact of several tertiary interactions on the global structure of the ribozyme. In addition, the data indicate that the formation of the P1.1 pseudoknot is the limiting step of the molecular mechanism. Last, as illustrated here, isothermal titration calorimetry appears to be a method of choice for the elucidation of an RNA's folding pathway. PMID:19134473

Reymond, Cedric; Bisaillon, Martin; Perreault, Jean-Pierre



A study of an extension of the frequency range applicable to analysis and titration  

E-print Network

for Titratioxx of Sodhxs ~xxMe and /pe'oohIOpio kOQp 9&vi ?ogoogoles s ~ i a a s o, ~ ~ N ~ XX, Table gXx Data fox' Titration of Sodinxx BFdroxxide ?nd ~bloxio kaid, 107, % Negaoyales, , . . . , ~. . . 36 XXX? Table XIXx Data Ac Titratioxx of Sodioxx Bfdroxx...???, ~ ?????, ??? ~ ?? w? + ~ ' Oraph IV) Absorption Curves ef gedtum gydrcndds and gydreehlorie heM? Long Here?? q? ~ ?????? ~ ? 33 Oxnph V, & Absorption Cucyee of Sodicne+@ioxQe and ~, ~hlorie AOM? Short Sere ? ? ~ ~ ~ ? ? ? ? ~ ~ ? Oreph VX& Titration Curve for tho...

Levine, Samuel W



Effect of realistic and filtered stellar photometric noise on the detection of moons using photometric transit timing  

NASA Astrophysics Data System (ADS)

The photometric transit timing technique was proposed by Szabó et al. (2006) as a method for discovering moons of transiting extrasolar planets. In the preliminary analysis of this technique, it was assumed that the noise in the transit lightcurve was well described by uncorrelated white noise. However, this assumption is not necessarily realistic. To determine the effect of using more realistic lightcurves, transit timing uncertainties are calculated for the case of white noise, measured solar photometric noise and measured solar photometric noise that has been filtered. It is found that for light curves contaminated with realistic photometric noise, the transit timing uncertainties are dramatically increased (and thus moon detection reduced). In addition, we find that while filtering reduced this problem, it did not negate it.

Lewis, K.



Photometric calibrations for 21st century science  

SciTech Connect

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 calibrated stars to provide precise calibration with an accuracy of equal to and better than 1% in the ultraviolet, visible and near-infrared portions of the spectrum, with excellent sky coverage and large dynamic range.

Kent, Stephen; /Fermilab; Kaiser, Mary Elizabeth; /Johns Hopkins U.; Deustua, Susana E.; /Baltimore, Space Telescope Sci.; Smith, J.Allyn; /Austin Peay State U.; Adelman, Saul; /Citadel Military Coll.; Allam, Sahar S.; /Fermilab; Baptista, Brian; /Indiana U.; Bohlin, Ralph C.; /Baltimore, Space Telescope Sci.; Clem, James L.; /Louisiana State U.; Conley, Alex; /Colorado U.; Edelstein, Jerry; /UC, Berkeley, Space Sci. Dept. /NOAO, Tucson



Photometric Studies of Orbital Debris at GEO  

NASA Technical Reports Server (NTRS)

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.

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



Photometric Studies of GEO Orbital Debris  

NASA Technical Reports Server (NTRS)

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 telescopes for that observation. Any change in color reflects a real change in the debris surface. We will compare our observations with models and laboratory measurements of selected surfaces.

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



Titrating Steroids on Exhaled Nitric Oxide in Children with Asthma A Randomized Controlled Trial  

Microsoft Academic Search

Rationale: Corticosteroids are the antiinflammatory treatment of choice in asthma. Treatment guidelines are mainly symptom-driven but symptoms are not closely related to airway inflammation. The fraction of nitric oxide in exhaled air (FENO) is a marker of airway inflammation in asthma. Objective: We evaluated whether titrating steroids on FENO improved asthma management in children. Methods: Eighty-five children with atopic asthma,

Marielle W. Pijnenburg; E. Marije Bakker; Wim C. Hop; Johan C. De Jongste


A spectroelectrochemical cell designed for low temperature electron paramagnetic resonance titration of oxygen-sensitive proteins.  


In this paper we describe an anaerobic titrator made virtually from glass with a small amount of high vacuum epoxy mounted directly to a quartz EPR tube. A complete titration may be carried out with as little as 600 microliters of sample. This cell features the anaerobic manipulation of an electrochemically poised solution from an electrochemical pouch to an EPR tube. The cell uses a gold foil working electrode and Ag/AgCl reference and counter electrodes. The reference and counter electrodes are isolated from the sample by leached Vycor glass. In the work reported here, we used this cell to determine the equilibrium redox potential of methyl viologen in an EPR titration. With methyl viologen as an indicator we found that the cell has a residual oxygen level of 1.5 microM with a leak rate of 0.005 nmol/min. After moving the solution into the EPR tube, freezing, performing EPR, and thawing, the potential of the methyl viologen solution drifted only 2 mV. During the titration, the poised potentials were stable, drifting only 1 mV/min. Formal potentials as low as -630 mV in a vitamin B12-type protein have been determined with this cell (S. R. Harder, W.-P. Lu, B. A. Feinberg, and S. W. Ragsdale (1989) Biochemistry, in press). PMID:2554761

Harder, S R; Feinberg, B A; Ragsdale, S W



Coupled chemical processes at clay\\/electrolyte interface: A batch titration study of Na-montmorillonites  

Microsoft Academic Search

The present work addresses the protolytic charge of montmorillonite, which occurs on the broken-bond sites at the particle edges. The purpose is to overcome the general difficulty arising in potentiometric titration due to coupled side reactions, which severely impede the titrant budget (partial dissolution of the clay and of secondary phases, hydrolysis and readsorption of dissolved species, cation exchange). Batch

Myriam Duc; Fabien Thomas; Fabien Gaboriaud




Microsoft Academic Search

A spectrophotometric study was made of the lithium, sodium, potassium, ; rubidium, cesium, beryllium, and magnesium salts of 1,3-dimethyl-5-; isonitrosobarbituric acid (1,3-dimethylvioluric acid, DMVA). The applicability ; of DMVA for the spectrophotometric titration of alkali and alkaline earth salts ; in aqueous solution was investigated. These metals were determined with an ; accuracy that ranged from 1 to 10 parts

M. E. Taylor; R. J. Robinson



proteinsSTRUCTURE O FUNCTION O BIOINFORMATICS Titration_DB: Storage and analysis of  

E-print Network

Science, Centre for Synthesis and Chemical Biology, UCD Conway Institute, University College Dublin properties of its folded versus unfolded states. The ionization of an isolated titratable group in a protein and Chemical Biology, UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland. E

McIntosh, Lawrence P.



E-print Network


Boyer, Edmond


Performing Titration Analyses for Water Quality. Module 17. Vocational Education Training in Environmental Health Sciences.  

ERIC Educational Resources Information Center

This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on performing titration analysis for water quality. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming each part of…

Consumer Dynamics Inc., Rockville, MD.


Coulometric Titration of Thiocyanate, Mercaptoacetic Acid, and ?-Mercaptopropionic Acid with Electrogenerated Hypobromite  

Microsoft Academic Search

Several sulfur containing ligands have been determined by coulometric titration using biamperometric end point detection. Satisfactory results were obtained for the direct determination of thiocyanate, mercaptoacetic acid and ?-mercaptopropionic acid. Silver has been determined by an indirect method involving the determination of excess precipitant.

R. J. Palma; H. K. L. Gupta; D. F. Boltz



Titration of fluoride with lanthanum chloride applying the biamperometric and the bipotentiometric end-point detection  

Microsoft Academic Search

Die Möglichkeiten der biamperometrischen und der bipotentiometrischen Endpunktbestimmung bei der Kaliumfluoridtitration mit Lanthanchlorid wurden unter Anwendung von Antimon-, Wismut-, Zinn- und Chinhydronelektrodenpaaren (Metallphase Platinum, Palladium und Gold) untersucht. In ungepufferten Fluoridlösungen mit 75 % Äthanolgehalt am Titrationsendpunkt wurden 5,72 mg Kaliumfluorid mit einer mittleren Abweichung von <0,8% bestimmt. Die erhaltenen Ergebnisse stimmten gut mit denen von potentiometrischer Titration überein.

Ferenc F. Gaál; Ljiljana S. Jovanovi?; Velimir D. Cani?



Thermodynamic analysis of Bacillus subtilis endospore protonation using isothermal titration calorimetry  

NASA Astrophysics Data System (ADS)

Bacterial proton and metal adsorption reactions have the capacity to affect metal speciation and transport in aqueous environments. We coupled potentiometric titration and isothermal titration calorimetry (ITC) analyses to study Bacillus subtilis spore-proton adsorption. We modeled the potentiometric data using a four and five-site non-electrostatic surface complexation model (NE-SCM). Heats of spore surface protonation from coupled ITC analyses were used to determine site specific enthalpies of protonation based on NE-SCMs. The five-site model resulted in a substantially better model fit for the heats of protonation but did not significantly improve the potentiometric titration model fit. The improvement observed in the five-site protonation heat model suggests the presence of a highly exothermic protonation reaction circa pH 7 that cannot be resolved in the less sensitive potentiometric data. From the log Ks and enthalpies we calculated corresponding site specific entropies. Log Ks and site concentrations describing spore surface protonation are statistically equivalent to B. subtilis cell surface protonation constants. Spore surface protonation enthalpies, however, are more exothermic relative to cell based adsorption suggesting a different bonding environment. The thermodynamic parameters defined in this study provide insight on molecular scale spore-surface protonation reactions. Coupled ITC and potentiometric titrations can reveal highly exothermic, and possibly endothermic, adsorption reactions that are overshadowed in potentiometric models alone. Spore-proton adsorption NE-SCMs derived in this study provide a framework for future metal adsorption studies.

Harrold, Zoë R.; Gorman-Lewis, Drew



Water Research 39 (2005) 579588 A high-resolution titrator: a new approach to studying  

E-print Network

Water Research 39 (2005) 579­588 A high-resolution titrator: a new approach to studying binding groups for sorption and to determine their affinities by considering their partial or total ionization of protons and the sorption capacities of the selected bioorganic matters were established. Sorption of lead

Volesky, Bohumil


Hydration and Lyotropic Melting of Amphiphilic Molecules: A Thermodynamic Study Using Humidity Titration Calorimetry  

Microsoft Academic Search

The hydration of the lipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and of the cationic detergent dodecyltrimethylammonium bromide (DTAB) has been studied by means of isothermal titration calorimetry (ITC), gravimetry, and infrared (IR) spectroscopy. During the experiments films of the amphiphiles are perfused by an inert gas of variable relative humidity. The measurement of adsorption heats using ITC represents a new adaptation of adsorption

H. Binder; B. Kohlstrunk; H. H. Heerklotz




E-print Network

TITRATION OF A BRUCELLA PROTEIN ALLERGEN IN SHEEP SENSITIZED WITH BRUCELLA MELITENSIS Lois M. JONES. INTRODUCTION A protein allergen extracted from a rough strain of B. melitensis was a highly potent agent in eliciting delayed hypersensitivity reactions in guinea pigs (JONES, DIAZ and TAYLOR, ig73). This allergen

Paris-Sud XI, Université de


DNA heats up: Energetics of genome ejection from phage revealed by isothermal titration calorimetry.  

E-print Network

1 DNA heats up: Energetics of genome ejection from phage revealed by isothermal titration-stranded DNA into bacteria upon receptor binding in an essentially spontaneous way. This downhill thermodynamic process from the intact virion toward the empty viral capsid plus released DNA is made possible


Determination of the Iodine Value of Selected Oils: An Experiment Combining FTIR Spectroscopy with Iodometric Titrations  

Microsoft Academic Search

An experiment has been developed that combines the FTIR analysis of oils and fats with an iodometric titration. While it is most appropriate for a sophomore or junior laboratory for majors, it also makes a suitable group project or demonstration for nonscience majors. Integration of the experiment into an upper-level biochemistry laboratory is described.

E. Eugene Gooch



Iodometric titration for determining the oxygen content of samples doped with Fe and Co  

Microsoft Academic Search

Double iodometric titration is a method developed for high-Tc superconductivity. It has been widely used to determine the effective oxidation of copper and to figure out the oxygen content in a sample in the past years. If a sample is doped with some metals like iron and cobalt, these metal ions can interfere in experiment results. This is a major

W. M. Chen; W. Hong; J. F. Geng; X. S. Wu; W. Ji; L. Y. Li; L. Qui; X. Jin



An accurate method of iodometric titration for determining oxygen content of superconducting cuprates  

Microsoft Academic Search

There are three problems existing in double iodometric titration. First, the calculating equation is too rough to obtain accurate results. Second, an error comes from iodine adsorbed by CuI. Third, when a sample is doped with iron-like elements, iron interferes with this method. The above problems were solved as following. We adopted a new equation, which may modify copper valence

W. M. Chen; N. L. Chen; C. C. Lam; J. Chen; X. S. Wu; X. Zhang; D. B. Chen; X. Jin



Acidbase equilibrium of ?-adrenoceptor blocking agents in acetic acid medium and methods for their titration  

Microsoft Academic Search

The overall dissociation constants and the formation constants of the perchlorate salts, in anhydrous acetic acid, of a series of ß-adrenoceptor blocking agents have been determined. On the basis of these values simple potentiometric and visual titration methods for the assay of ß-adrenoceptor blocking drugs in acetic acid are described.

José Barbosa; Maria Eleno Torrero




Microsoft Academic Search

A comparison was made of a number of direct complexometric titrations ; previously published ior the determination of yttrium and the lanthanons. ; Working and optimum pH ranges were obtained for what are considered to be the ; best indicators, Alizarin Red S screened with Methylene Blue, Eriochrome Black T, ; Copper-Naphthyl Azoxine, and Xylenol Orange. The precision and accuracy

S. J. Lyle



Thermodynamics of cationic lipid-DNA complex formation as studied by isothermal titration calorimetry.  

PubMed Central

The detailed analysis of the cationic lipid-DNA complex formation by means of isothermal titration calorimetry is presented. Most experiments were done using 1,2-dioleyl-sn-glycero-3-ethylphosphocholine (EDOPC), but basic titrations were also done using DOTAP, DOTAP:DOPC, and DOTAP:DOPE mixtures. Complex formation was endothermic with less than 1 kcal absorbed per mole of lipid or DNA charge. This enthalpy change was attributed to DNA-DNA mutual repulsion within the lamellar complex. The exception was DOTAP:DOPE-containing lipoplex for which the enthalpy of formation was exothermic, presumably because of DOPE amine group protonation. Experimental conditions, namely, direction and titration increment as well as concentration of titrant, which dictate the structure of resulting lipoplex (whether lamellar complex or DNA-coated vesicle), were found to affect the apparent thermodynamics of complex formation. The structure, in turn, influences the biological properties of the lipoplex. If the titration of lipid into DNA was carried out in large increments, the DeltaH was larger than when the injection increments were smaller, a finding that is consistent with increased vesicle disruption under large increments and which is expected theoretically. Cationic lipid-DNA binding was weak in high ionic strength solutions, however, the effective binding constant is within micromolar range because of macromolecular nature of the interaction. PMID:12080142

Pozharski, Edwin; MacDonald, Robert C



An improved telemedicine system for remote titration and optimization of Home Mechanical Ventilation  

Microsoft Academic Search

Home Mechanical Ventilation is applied to patients with different chronic respiratory diseases and, in order to be effective, it requires accurate individual titration. Nowadays this can be obtained only in the hospital during day or night visits, and this is associated with long waiting lists and high costs. The aim of this work was to realize and test a simple

Leonardo Govoni; R. Farre?; Antonio Pedotti; Josep M. Montserrat; Raffaele L. Dellaca



Propagation of error in fulvic acid titration data: a comparison of three analytical methods  

E-print Network

commonly used analytical methods: ion-selective electrodes, anodic strip- ping voltammetry, fluorescence using ion-selective electrodes and fixed-potential ampero- metry. The results of these comparisons selective electrode and fluorescence quenching data and Waite and Morel (3) compared fulvic acid titrations

Morel, François M. M.


Prednisone for chronic active liver disease: dose titration, standard dose, and combination with azathioprine compared  

Microsoft Academic Search

Among 120 consecutive patients with chronic active liver disease (CALD) randomized to different treatments, those receiving maintenance doses of prednisone 20 mg daily (Pred), prednisone in doses given on alternate days and titrated to secure resolution of clinical and biochemical abnormalities (Pred-Titrad), or a combination of prednisone 10 mg and azathioprine 50 mg daily (Comb) survived and underwent resolution of

W H Summerskill; M G Korman; H V Ammon; A H Baggenstoss



Titration of a Solid Acid Monitored by X-Ray Diffraction  

ERIC Educational Resources Information Center

An experiment is described to introduce students to an important class of solid-state reactions while reinforcing concepts of titration by using a pH meter and a powder X-ray diffractometer. The experiment was successful in teaching students the abstract concepts of solid-state structure and diffraction by applying the diffraction concepts learned…

Dungey, Keenan E.; Epstein, Paul




Microsoft Academic Search

Complexometric titration of thorium in solutions containing calcium, ; zirconium, titanium, and rare earths with the use of Fe(SCN)âindicator was ; studied. A titrimetric method was developed for determining thorium in natural ; materials containing large amounts of zirconium and titanium with the use of ; iodate and oxalate precipitation, as well as a colorimetric end-paint, when small ; quantities




On-line titration method for monitoring buffer capacity and total volatile fatty acid levels in anaerobic digesters.  


The construction and use of an automatic on-line titration unit for routine or event- initiated monitoring of alkalinity, buffer capacity, and volatile fatty acid (VFA) levels is presented. Under computer control a sample of digester liquor is pumped into the titration vessel and weighed. A sequence of titration, sparging, and back-titration operations are then initiated during which the pH and weight are recorded continuously and a titration curve constructed. From the curve, estimates of the alkalinity, buffer capacity to any desired pH endpoint, and total VFA levels are computed. The data is stored to disk and output as hard copy together with the titration curve itself. Monitoring and control of the titration apparatus is effected by a microcomputer via two analog input lines and eight digital output lines, respectively. The system is suitable for downloading to a small, inexpensive dedicated microprocessor-based system. The apparatus is constructed from standard and widely available equipment and the titration sequence, being under software control, is fully adaptable to particular requirements. The use of this facility in the on-line monitoring, control and optimization of the anaerobic digestion process is discussed. PMID:18587953

Powell, G E; Archer, D B



The Quantitative Resolution of a Mixture of Group II Metal Ions by Thermometric Titration with EDTA. An Analytical Chemistry Experiment.  

ERIC Educational Resources Information Center

Presents an experiment in thermometric titration used in an analytic chemistry-chemical instrumentation course, consisting of two titrations, one a mixture of calcium and magnesium, the other of calcium, magnesium, and barium ions. Provides equipment and solutions list/specifications, graphs, and discussion of results. (JM)

Smith, Robert L.; Popham, Ronald E.



Acid-base titrations for polyacids: Significance of the pK sub a and parameters in the Kern equation  

NASA Technical Reports Server (NTRS)

A new method is suggested for calculating the dissociation constants of polyvalent acids, especially polymeric acids. In qualitative form the most significant characteristics of the titration curves are demonstrated and identified which are obtained when titrating the solutions of such acids with a standard base potentiometrically.

Meites, L.



Modeling metal binding by dissolved humic substance: a revisit to the fluorometric titration approach.  


It is desirable to directly investigate metal cation binding by dissolved humic substance (HS) in environmental samples without isolation and purification of the HS. This is commonly achieved by the fluorometric titration approach, in which the variations of the HS components' fluorescence when titrated with metal cations, such as cupric ions (Cu(2+)), were commonly resolved by a well-established chemometric tool called parallel factor analysis and fit to a classical nonlin ear equation to obtain cation binding parameters. The nonlinear expression was derived based on the two assumptions that a given HS component (e.g., L) binds Cu(2+) with a 1:1 stoichiometry, forming only the complex LCu, and that other ligands competing with L for Cu(2+) are not explicitly considered. Given the deviations (e.g., the presence of multiple HS components competing for Cu(2+) and a likely 2:1 binding stoichiometry in addition to the 1:1 binding) from the assumptions, the fitting-derived binding parameters reported in past studies are questionable; those studies commonly reported high goodness-of-fit (R(2)) as a support of the validity of the assumptions. This study deconstructed the current equation and examined it with two organic ligand components in a simulated study to see what conditions could also yield a good fit. It turned out that high a R(2) value ranging between 0.9971 and 1.0 was observed despite the deviations from the above-mentioned assumptions. In addition, this study re-evaluated some published experimental data from these past studies and found that the fitting-derived parameters could not be accounted for based on the above-mentioned assumptions. The findings in this study therefore indicate that the current fluorometric titration approach is problematic when investigating HS component interactions with metal ions in situ. The combination of ion-selective electrode and fluorometric titration may be an alternative to the current fluorometric titration approach alone. PMID:24694698

Chen, Hao; Meng, Wei; Lei, Kun



A disposable voltammetric cell for determining the titratable acidity in vinegar.  


A disposable voltammetric cell using three pencil leads as working, reference, and counter electrodes was developed for determining the titratable acidity, i.e. the acid content in vinegar. The materials of the pencil leads were graphite-reinforcement carbons (GRCs). A voltammetric determination of acid was made by measuring the reduction prepeak current of 3,5-di-t-butyl-1,2-benzoquinone (DBBQ) due to the presence of acids in unbuffered solution. The potential stability of the pseudo-reference electrode of GRC was examined. The prepeak current was found to be proportional to the acetic acid concentration from 0.05 to 2.7 mM with a correlation coefficient of 0.999. The cell-to-cell reproducibility for 1 mM acetic acid was evaluated with ten individual disposable cells. The RSD of the prepeak current and the SD of the prepeak potential were 2.56% and 0.008, respectively. The titratable acidity in five vinegar samples was determined by voltammetry using disposable cells and compared with that of the titratable acidity determined by the conventional potentiometric titration method. We then observed the results by both methods, and found a correlation coefficient of 0.972. As such, the voltammetry using disposable-cell required only one thousandth the volume of a vinegar sample for the titration method. The disposable cell was superior to the conventional electrochemical cell, in terms of facility, environment-friendly, and economy, and thus a sensor using the present cell would be useful for routine work in the quality control of vinegar. PMID:14640441

Kotani, Akira; Miyaguchi, Yuji; Harada, Dai; Kusu, Fumiyo



Safety and tolerability of different titration rates of retigabine (ezogabine) in patients with partial-onset seizures.  


Retigabine (RTG; international nonproprietary name)/ezogabine (EZG; US adopted name) is an antiepileptic drug (AED) that prolongs neuronal voltage-gated potassium-channel KCNQ2-5 (Kv 7.2-7.5) opening. This double-blind study evaluated different RTG/EZG dose-titration rates. Patients (N=73) with partial-onset seizures receiving concomitant AEDs were randomized to one of three titration groups, all of which were initiated at RTG/EZG 300mg/day divided into three equal doses. Fast-, medium-, and slow-titration groups received dose increments of 150mg/day every 2, 4, and 7 days, respectively, achieving the target dose of 1200mg/day after 13, 25, and 43 days, respectively. Safety assessments were performed throughout. Discontinuation rates due to treatment-emergent adverse events (TEAEs) were numerically higher in the fast- (10/23) and medium- (7/22) titration groups than in the slow-titration group (3/23) but statistical significance was achieved only for the high-titration group compared with the low-titration group (p=0.024). Stratified analysis, with concomitant AEDs divided into enzyme inducers (carbamazepine, phenytoin, oxcarbazepine) or noninducers, showed that the risk of discontinuation due primarily to TEAEs was significantly higher in the fast- (p=0.010) but not in the medium-titration group (p=0.078) when compared with the slow-titration group. Overall, the slow-titration rate appeared to be best tolerated and was used in further efficacy and safety studies with RTG/EZG. PMID:24094693

Biton, Victor; Gil-Nagel, Antonio; Brodie, Martin J; Derossett, Sarah E; Nohria, Virinder



Photometric Calibration of Consumer Video Cameras  

NASA Technical Reports Server (NTRS)

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 analyze. The light source used to generate the calibration images is an artificial variable star comprising a Newtonian collimator illuminated by a light source modulated by a rotating variable neutral- density filter. This source acts as a point source, the brightness of which varies at a known rate. A video camera to be calibrated is aimed at this source. Fixed neutral-density filters are inserted in or removed from the light path as needed to make the video image of the source appear to fluctuate between dark and saturated bright. The resulting video-image data are analyzed by use of custom software that determines the integrated signal in each video frame and determines the system response curve (measured output signal versus input brightness). These determinations constitute the calibration, which is thereafter used in automatic, frame-by-frame processing of the data from the video images to be analyzed.

Suggs, Robert; Swift, Wesley, Jr.



Photometric imaging in particle size measurement and surface visualization.  


The aim of this paper is to give an insight into photometric particle sizing approaches, which differ from the typical particle size measurement of dispersed particles. These approaches can often be advantageous especially for samples that are moist or cohesive, when dispersion of particles is difficult or sometimes impossible. The main focus of this paper is in the use of photometric stereo imaging. The technique allows the reconstruction of three-dimensional images of objects using multiple light sources in illumination. The use of photometric techniques is demonstrated in at-line measurement of granules and on-line measurement during granulation and dry milling. Also, surface visualization and roughness measurements are briefly discussed. PMID:21075186

Sandler, Niklas



Multi-image photometric solutions for the Galilean satellites  

NASA Technical Reports Server (NTRS)

A method for determining the limb darkening planet, acquired in the same wavelength range (lambda), within a few degrees of the same phase angle (alpha), but acquired at different illumination and viewing conditions. The two images are first geometrically registered in simple cylindrical format. A limb darkening factor is computed for each pixel pair and output as a digital image. Systematic trends with photometric coordinates across this image indicate either a calibration error or inappropriateness of the particular photometric function. This method can be used for any photometric function with a single limb darkening factor, such as the Minnaert function or the function which combines the Lommel-Seeliger and Lambert functions. By solving for many pairs of images, the limb darkening factor as a function of alpha and lambda may be determined. The two image limb darkening solutions determined for 1 Voyager image pair on Ganymede, 16 image pairs on Callisto, 44 pairs on Europa, and 19 pairs on Io are discussed.

Mcewen, A. S.; Soderblom, L. A.



Photometric Analysis in the Kepler Science Operations Center Pipeline  

NASA Technical Reports Server (NTRS)

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.

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



Towards a photometric metallicity scale for open clusters  

NASA Astrophysics Data System (ADS)

Context. Open clusters are a useful tool when investigating several topics connected with stellar evolution; for example the age or distance can be more accurately determined than for field stars. However, one important parameter, the metallicity, is only known for a marginal percentage of open clusters. Aims: We aim at a consistent set of parameters for the open clusters investigated in our photometric ?a survey of chemically peculiar stars. Special attention is paid to expanding our knowledge of cluster metallicities and verifying their scale. Methods: Making use of a previously developed method based on normalised evolutionary grids and photometric data, the distance, age, reddening, and metallicity of open clusters were derived. To transform photometric measurements into effective temperatures to use as input for our method, a set of temperature calibrations for the most commonly used colour indices and photometric systems was compiled. Results: We analysed 58 open clusters in total. Our derived metallicity values were in excellent agreement with about 30 spectroscopically studied targets. The mean value of the absolute deviations was found to be 0.03 dex, with no noticeable offset or gradient. The method was also applied using recent evolutionary models based on the currently accepted lower solar abundance value Z ~ 0.014. No significant differences were found compared to grids using the former adopted solar value Z = 0.02. Furthermore, some divergent photometric datasets were identified and discussed. Conclusions: The method provides an accurate way of obtaining properly scaled metallicity values for open clusters. In light of present and future homogeneous photometric sky surveys, the sample of stellar clusters can be extended to the outskirts of the Milky Way, where spectroscopic studies are almost impossible. This will help for determining galactic metallicity gradients in more detail. Figure 7 is available in electronic form at

Netopil, M.; Paunzen, E.



Photometric Redshifts for Galaxies in the GOODS Southern Field  

NASA Astrophysics Data System (ADS)

We use extensive multiwavelength photometric data from the Great Observatories Origins Deep Survey to estimate photometric redshifts for a sample of 434 galaxies with spectroscopic redshifts in the Chandra Deep Field-South. Using the Bayesian method, which incorporates redshift/magnitude priors, we estimate photometric redshifts for galaxies in the range 18photometric redshifts for several special subclasses of objects. The results for extremely red objects are more accurate than those for the sample as a whole, with ?=0.051 and very few outliers (3%). Photometric redshifts for active galaxies, identified from their X-ray emission, have a dispersion of ?=0.104, with 10% outlier fraction, similar to that for normal galaxies. Employing a redshift/magnitude prior in this process seems to be crucial in improving the agreement between photometric and spectroscopic redshifts. Based on observations taken with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. This work is supported by NASA through grant GO09583.01-96A. Based on observations collected at the European Southern Observatory, Chile (ESO programmes 168.A-0485, 170.A-0788, 64.O-0643, 66.A-0572, 68.A-0544, 164.O-0561, 169.A-0725, 267.A-5729 66.A-0451, 68.A-0375 164.O-0561, 267.A-5729, 169.A-0725, and 64.O-0621).

Mobasher, B.; Idzi, R.; Benítez, N.; Cimatti, A.; Cristiani, S.; Daddi, E.; Dahlen, T.; Dickinson, M.; Erben, T.; Ferguson, H. C.; Giavalisco, M.; Grogin, N. A.; Koekemoer, A. M.; Mignoli, M.; Moustakas, L. A.; Nonino, M.; Rosati, P.; Schirmer, M.; Stern, D.; Vanzella, E.; Wolf, C.; Zamorani, G.




SciTech Connect

The next generation of proposed galaxy surveys will increase the number of galaxies with photometric redshift identifications by two orders of magnitude, drastically expanding both the redshift range and detection threshold from the current state of the art. Obtaining spectra for a fair subsample of these new data could be cumbersome and expensive. However, adequate calibration of the true redshift distribution of galaxies is vital to tapping the potential of these surveys to illuminate the processes of galaxy evolution and to constrain the underlying cosmology and growth of structure. We examine here an alternative to direct spectroscopic follow-up: calibration of the redshift distribution of photometric galaxies via cross-correlation with an overlapping spectroscopic survey whose members trace the same density field. We review the theory, develop a pipeline to implement the method, apply it to mock data from N-body simulations, and examine the properties of this redshift distribution estimator. We demonstrate that the method is generally effective, but the estimator is weakened by two main factors. One is that the correlation function of the spectroscopic sample must be measured in many bins along the line of sight, which renders the measurement noisy and interferes with high-quality reconstruction of the photometric redshift distribution. Also, the method is not able to disentangle the photometric redshift distribution from redshift dependence in the bias of the photometric sample. We establish the impact of these factors using our mock catalogs. We conclude that it may still be necessary to spectroscopically follow up a fair subsample of the photometric survey data. Nonetheless, it is significant that the method has been successfully implemented on mock data, and with further refinement it may appreciably decrease the number of spectra that will be needed to calibrate future surveys.

Schulz, A. E., E-mail: schulz@ias.ed [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)



Spectro-Photometric Constraints on Galaxy Evolution with NGST  

E-print Network

The Next Generation Space Telescope (NGST) will gather unprecedented spectro-photometric data on galaxies out to the highest redshifts. It is therefore crucial to identify the spectro-photometric diagnostics within reach of NGST, which will allow us to best constrain the history of star formation and evolution of galaxies. The primary parameters to be determined are the ongoing rate of star formation and stellar mass of galaxies at all redshifts. In this context, we briefly review the reliability of various star formation rate and mass estimators of galaxies in a full range of redshifts, with particular emphasis on the relative merits of optical versus near- to mid-IR observations.

S. Charlot



Steps Toward a Common Near-Infrared Photometric System  

E-print Network

The proliferation of near-infrared (1--5 $\\mu$m) photometric systems over the last 30 years has made the comparison of photometric results difficult. In an effort to standardize infrared filters in use, the Mauna Kea Observatories near-infrared filter set has been promoted among instrument groups through combined filter production runs. The characteristics of this filter set are summarized, and some aspects of the filter wavelength definitions, the flux density for zero magnitude, atmospheric extinction coefficients, and color correction to above the atmosphere are discussed.

A. T. Tokunaga W. D. Vacca



CosmoPhotoz: Photometric redshift estimation using generalized linear models  

NASA Astrophysics Data System (ADS)

CosmoPhotoz determines photometric redshifts from galaxies utilizing their magnitudes. The method uses generalized linear models which reproduce the physical aspects of the output distribution. The code can adopt gamma or inverse gaussian families, either from a frequentist or a Bayesian perspective. A set of publicly available libraries and a web application are available. This software allows users to apply a set of GLMs to their own photometric catalogs and generates publication quality plots with no involvement from the user. The code additionally provides a Shiny application providing a simple user interface.

de Souza, Rafael S.; Elliott, Jonathan; Krone-Martins, Alberto; Ishida, Emille E. O.; Hilbe, Joseph; Cameron, Ewan




SciTech Connect

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 = 1.0-1.4 are well described by an exponentially decaying star formation history with scale {tau} = 100-200 Myr, age around 1.5-2.0 Gyr, solar or slightly sub-solar metallicity, and moderate extinction, A(V) {approx} 0.5 mag. We also find that galaxies with masses above M* are typically older than lighter galaxies, as expected in a downsizing scenario of galaxy formation. This trend is, however, model dependent, i.e., it is significantly more evident in the results obtained with some stellar population synthesis libraries, and almost absent in others.

Perez-Gonzalez, Pablo G.; Cava, Antonio; Barro, Guillermo; Villar, Victor; Cardiel, Nicolas; Espino, Nestor; Gallego, Jesus [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)] [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Ferreras, Ignacio [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom)] [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Rodriguez-Espinosa, Jose Miguel; Balcells, Marc; Cepa, Jordi [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain)] [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Alonso-Herrero, Almudena [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain)] [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain); Cenarro, Javier [Centro de Estudios de Fisica del Cosmos de Aragon, Plaza San Juan 1, Planta 2, E-44001 Teruel (Spain)] [Centro de Estudios de Fisica del Cosmos de Aragon, Plaza San Juan 1, Planta 2, E-44001 Teruel (Spain); Charlot, Stephane [Institut d'Astrophysique de Paris, CNRS, Universite Pierre and Marie Curie, UMR 7095, 98bis bd Arago, F-75014 Paris (France)] [Institut d'Astrophysique de Paris, CNRS, Universite Pierre and Marie Curie, UMR 7095, 98bis bd Arago, F-75014 Paris (France); Cimatti, Andrea [Dipartimento di Astronomia, Universita degli Studi di Bologna, I-40127 Bologna (Italy)] [Dipartimento di Astronomia, Universita degli Studi di Bologna, I-40127 Bologna (Italy); Conselice, Christopher J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Daddi, Emmanuele; Elbaz, David [CEA, Laboratoire AIM, Irfu/SAp, F-91191 Gif-sur-Yvette (France)] [CEA, Laboratoire AIM, Irfu/SAp, F-91191 Gif-sur-Yvette (France); Donley, Jennifer [Los Alamos National Laboratory, Los Alamos, NM (United States)] [Los Alamos National Laboratory, Los Alamos, NM (United States); Gobat, R. [Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d'Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)] [Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d'Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); and others



Bootstrapping de-shadowing and self-calibration for scanning electron microscope photometric stereo  

NASA Astrophysics Data System (ADS)

In this paper, we present a novel approach that addresses the blind reconstruction problem in scanning electron microscope (SEM) photometric stereo. Using only two observed images that suffer from shadowing effects, our method automatically calibrates the parameter and resolves shadowing errors for estimating an accurate three-dimensional (3D) shape and underlying shadowless images. We introduce a novel shadowing compensation model using image intensities for both cases of presence and absence of shadowing. With this model, the proposed de-shadowing algorithm iteratively compensates for image intensities and modifies the corresponding 3D surface. Besides de-shadowing, we introduce a practically useful self-calibration criterion by enforcing a good reconstruction. We show that incorrect parameters will engender significant distortions of 3D reconstructions in shadowed regions during the de-shadowing procedure. This motivated us to design the self-calibration criterion by utilizing shadowing to pursue the proper parameter that produces the best reconstruction with least distortions. As a result, we develop a bootstrapping approach for simultaneous de-shadowing and self-calibration in SEM photometric stereo. Extensive experiments on real image data demonstrate the effectiveness of our method.

Miyamoto, Atsushi; Chen, Deshan; Kaneko, Shun’ichi



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

NASA Astrophysics Data System (ADS)

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.

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



Novel Methods for Predicting Photometric Redshifts from Broadband Photometry Using Virtual Sensors  

NASA Astrophysics Data System (ADS)

We calculate photometric redshifts from the Sloan Digital Sky Survey Main Galaxy Sample, the Galaxy Evolution Explorer All Sky Survey, and the Two Micron All Sky Survey using two new training-set methods. We utilize the broadband photometry from the three surveys alongside Sloan Digital Sky Survey measures of photometric quality and galaxy morphology. Our first training-set method draws from the theory of ensemble learning while the second employs Gaussian process regression, both of which allow for the estimation of redshift along with a measure of uncertainty in the estimation. The Gaussian process models the data very effectively with small training samples of approximately 1000 points or less. These two methods are compared to a well-known artificial neural network training-set method and to simple linear and quadratic regression. We also demonstrate the need to provide confidence bands on the error estimation made by both classes of models. Our results indicate that variations due to the optimization procedure used for almost all neural networks, combined with the variations due to the data sample, can produce models with variations in accuracy that span an order of magnitude. A key contribution of this paper is to quantify the variability in the quality of results as a function of model and training sample. We show how simply choosing the ``best'' model given a data set and model class can produce misleading results.

Way, M. J.; Srivastava, A. N.



Amperometry with two polarisable electrodes-XI Determination of bismuth by EDTA titration.  


Optimum conditions have been found for a highly selective determination of bismuth via EDTA titration with biamperometric indication of the end-point. The influence of the applied potential, pH and stirring on the accuracy and selectivity of the determination has been studied. In a medium of 0.4M nitric acid only high concentrations of iron(III) and copper(II) interfere with the determination of bismuth. Zirconium, thallium(III) and indium interfere even in small concentrations. The average error of the determination of 5-100 mg of bismuth (when titrated with 0.05M EDTA solution) is +/-0-1 % rel. and for the determination of 0.5-10 mg it is +/-0.3% rel. (0.005M EDTA). The method has been verified by the analysis of a Wood's metal of known composition. PMID:18959921

Vydra, F; Vorlícek, J



Rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers  

SciTech Connect

A rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers has been validated using the pararosaniline-formaldehyde (PRA) method of West and Gaeke. This air-titration (iodate) method is an adaptation of iodometric methods using a starch indicator. Potassium iodate and an excess of potassium iodide are used in the reaction. Sampling is completed in ten minutes or less and concentration is calculated by use of a simple formula. Linear equations were derived over the range of concentrations from 0.5 to 100 ppm SO/sub 2/ for uncorrected iodate bubbler results, data corrected for tandem bubbler concentrations and data corrected for mean iodate bubbler efficiency. Linear correlation with the PRA method over this range was 0.999 for all three sets of data.

Snyder, E.A.; Palmes, E.D.



Investigation of the formation of peroxide in. gamma. -irradiated polyethylene by the method of iodometric titration  

SciTech Connect

The concentrations of hydroperoxides (HP) and dialkyl peroxides (DAP) in polyethylene (PE) powder, ..gamma.. irradiated in air at 295 K at a dose of 0.22-2.8 J/(kg x sec) up to doses of 16-300 kJ/kg, were determined by various methods of iodometric titration. Under the indicated conditions, the HP concentration reached 0.18 mole/kg, DPA 0.07 mole/kg, G /SUB HP/ was 8.3 1/100 eV; G /SUB GP/ ..integral..I /SUP -0.5/ . On the basis of the total absence of grafting of acrylamide onto ..gamma..-irradiated PE after reduction during titration of HP in it, it was concluded that grafted polymerization is initiated by the radicals of thermal decomposition of HP in PE.

Savost'yanov, V.S.; Kritskaya, D.A.; Ponomarev, A.N.



Standard test method for aluminum in iron ores by complexometric titration  

SciTech Connect

This method covers the determination of aluminum in iron ores, concentrates, and agglomerates in the concentration range from 0.25 to 5% aluminium. The sample is fused in a zirconium crucible with a mixed flux of sodium carbonate and sodium peroxide. The fused mass is dissolved in dilute hydrochloric acid. The R/sub 2/O/sub 3/ hydroxides are precipitated with ammonia and redissolved in hydrochloric acid. Iron, titanium, etc., are removed with cupferron and chloroform. The aqueous phase is treated with nitric and perchloric acids and evaporated to dryness. After dissolving in dilute hydrochloric acid, the solution is filtered, and the filtrate is treated with an excess of ethylenediaminetetraacetic acid (EDTA). The excess EDTA is titrated with a standard zinc solution using xylenol orange indicator. Ammonium fluoride is added to release the EDTA bound to aluminum. This EDTA is then titrated with standard zinc solution, and the percent aluminum is calculated.

Not Available



Intraoperative management of heart-lung interactions: "from hypothetical prediction to improved titration".  


Extensive literature describes the suitability of dynamic parameters to predict responsiveness in fluid. However, based on heart-lung interactions, these parameters can have serious limitations, including the use of protective lung ventilation. Although the latter seems to be beneficial for healthy patients undergoing high-risk surgery, the intraoperative interpretation of dynamic parameters to predict fluid responsiveness can be hazardous. In this context, the attending physician could, alternatively, titrate the need of fluids with a small fluid challenge, which remains unaffected by low tidal volume, the presence of arrhythmia, or the presence of spontaneous ventilation. When intraoperative prediction of fluid responsiveness is required in mechanically ventilated patients, "improved" titration should be preferred to a hypothetical prediction. PMID:25127853

Ouattara, A; Dewitte, A; Rozé, H



A rapid air titration method for determining SO2 concentration in inhalation chambers.  


A rapid air titration method for determining SO2 concentration in inhalation chambers has been validated using the pararosaniline-formaldehyde (PRA) method of West and Gaeke. This air-titration (iodate) method is an adaptation of iodometric methods using a starch indicator. Potassium iodate and an excess of potassium iodide are used in the reaction. Sampling is completed in ten minutes or less and concentration is calculated by use of a simple formula. Linear equations were derived over the range of concentrations from 0.5 to 100 ppm SO2 for uncorrected iodate bubbler results, data corrected for tandem bubbler concentrations and data corrected for mean iodate bubbler efficiency. Linear correlation with the PRA method over this range was 0.999 for all three sets of data. PMID:4014008

Snyder, E A; Palmes, E D



Hydrolysis-precipitation studies of aluminum (III) solutions. I. Titration of acidified aluminum nitrate solutions  

Microsoft Academic Search

Acidified aluminum nitrate solutions were titrated with alkali (NaOH or KOH) over a temperature range of 24°C to 90°C. A homogeneous distribution of added base was achieved by: (i) in situ decomposition of urea (90°C); and (ii) a novel method involving injection through a capillary submerged in the agitated salt solution.\\u000a\\u000aThe experimental pH curves are characterized by two plateaus

A. C. Vermeulen; John W. Geus; R. J. Stol; P. L. de Bruyn



On the total CO2-titration alkalinity-oxygen system in the Pacific Ocean  

Microsoft Academic Search

Decomposition of organic matter changes the concentrations of carbon, nitrogen, phosphorus, oxygen and titration alkalinity (TA) in the ratio 106:16:1:138:-17 (refs 1-3), so the combined effect of decomposing x mol of CaCO3 and y mol of organic matter in 1 kg of seawater on the preformed total CO2 (SigmaCO2 0), preformed TA (TA0), biogenerated SigmaCO2 [DeltaSigmaCO2(biol)] and the apparent oxygen

Chen-Tung A. Chen; Ricardo M. Pytkowicz



Micellization of Bovine ?-Casein Studied by Isothermal Titration Microcalorimetry and Cryogenic Transmission Electron Microscopy  

Microsoft Academic Search

The association behavior, critical micellization concentration (CMC), and enthalpy of demicellization (¢Hdemic) of bovine ‚-casein were studied, for the first time by isothermal titration calorimetry, in a pH 7.0 phosphate buffer with 0.1 ionic strength and in pure water. In the buffer solutions, the CMC decreased asymptotically from 0.15 to 0.006 mM as the temperature was raised from 16 to

Irina Portnaya; Uri Cogan; Yoav D. Livney; Ory Ramon; Karin Shimoni; Moshe Rosenberg; Dganit Danino



Semi-automatic version of the potentiometric titration method for characterization of uranium compounds.  


The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. PMID:22406220

Cristiano, Bárbara F G; Delgado, José Ubiratan; da Silva, José Wanderley S; de Barros, Pedro D; de Araújo, Radier M S; Dias, Fábio C; Lopes, Ricardo T



A Geochemical Reaction Model for Titration of Contaminated Soil and Groundwater at the Oak Ridge Reservation  

NASA Astrophysics Data System (ADS)

This study investigates geochemical reactions during titration of contaminated soil and groundwater at the Oak Ridge Reservation in eastern Tennessee. The soils and groundwater exhibits low pH and high concentrations of aluminum, calcium, magnesium, manganese, various trace metals such as nickel and cobalt, and radionuclides such as uranium and technetium. The mobility of many of the contaminant species diminishes with increasing pH. However, base additions to increase pH are strongly buffered by various precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior and associated geochemical effects is thus critical to evaluate remediation performance of pH manipulation strategies. This study was undertaken to develop a practical but generally applicable geochemical model to predict aqueous and solid-phase speciation during soil and groundwater titration. To model titration in the presence of aquifer solids, an approach proposed by Spalding and Spalding (2001) was utilized, which treats aquifer solids as a polyprotic acid. Previous studies have shown that Fe and Al-oxyhydroxides strongly sorb dissolved Ni, U and Tc species. In this study, since the total Fe concentration is much smaller than that of Al, only ion exchange reactions associated with Al hydroxides are considered. An equilibrium reaction model that includes aqueous complexation, precipitation, ion exchange, and soil buffering reactions was developed and implemented in the code HydroGeoChem 5.0 (HGC5). Comparison of model results with experimental titration curves for contaminated groundwater alone and for soil- water systems indicated close agreement. This study is expected to facilitate field-scale modeling of geochemical processes under conditions with highly variable pH to develop practical methods to control contaminant mobility at geochemically complex sites.

Zhang, F.; Parker, J. C.; Gu, B.; Luo, W.; Brooks, S. C.; Spalding, B. P.; Jardine, P. M.; Watson, D. B.



Rapid semi-micro potentiometric titration of Ir(IV) with hydrazine sulphate  

SciTech Connect

A rapid potentiometric titration of Ir(IV) with hydrazine sulphate is described. 1.0 mg, 0.25 mg and 0.10 mg are determined with precision of 0.5%, 0.8% and 3.0%, respectively. Most of the common ions do not interfere as well as Rh(III). Some determinations of Ir(IV) in ores made with good precision and compared with a spectrophotometric method.

Lichtig, J.; ALves, J.C. [Universidade de Sao Paulo (Brazil)



Investigation of the formation of peroxide in. gamma. -irradiated polyethylene by the method of iodometric titration  

Microsoft Academic Search

The concentrations of hydroperoxides (HP) and dialkyl peroxides (DAP) in polyethylene (PE) powder, ..gamma.. irradiated in air at 295 K at a dose of 0.22-2.8 J\\/(kg x sec) up to doses of 16-300 kJ\\/kg, were determined by various methods of iodometric titration. Under the indicated conditions, the HP concentration reached 0.18 mole\\/kg, DPA 0.07 mole\\/kg, G \\/SUB HP\\/ was 8.3

V. S. Savostyanov; D. A. Kritskaya; A. N. Ponomarev



Complexometric titration of copper(II) using nitrosochromotropic acid as a new metal indicator  

Microsoft Academic Search

Nitrosochromotropic acid gives a violet coloured soluble complex with CuII in ammonium chloride-ammonium hydroxide buffer solution, which is less stable than CuII-EDTA complex. When microquantities of CuII solution containing 1 or 2 drops of nitrosochromotropic acid in the ph range 7.25 to 8.00, are titrated with EDTA, a sharp colour change from violet to orange occurs at the end point.

C. S. Pande; T. S. Srivastava



The generalized lewis acid-base titration of palladium and niobium  

Microsoft Academic Search

The high thermodynamic stability of alloys composed of platinum group metals and group IVB and VB metals has been explained\\u000a by an electronic interaction analogous to the Lewis acid-base concept for nontransition elements. The analogy is further demonstrated\\u000a by the titration of palladium by addition of niobium. The activity of niobium in solid palladium was measured as a function\\u000a of

M. Cima; L. Brewer



Isothermal titration calorimetric studies of the pH induced conformational changes of bovine serum albumin  

Microsoft Academic Search

Bovine serum albumin (BSA) is a soft globular protein that undergoes conformational changes through several identified transition\\u000a steps in the pH range 2–13.5. The ability to change conformation makes BSA capable of complexing different ligands from fatty\\u000a acids to cations or drugs and carries them in the bloodstream. Microcalorimetric titration of BSA with NaOH solution was performed\\u000a to measure the

Robert Kun; Márta Szekeres; Imre Dékány



Photometric Observations of Asteroid 433 Eros during 2012 Apparition  

NASA Astrophysics Data System (ADS)

A total of 55 clear-filtered photometric observations of the near-Earth asteroid 433 Eros were made on four nights from Holtsville Observatory during the 2012 apparition. The lightcurves were plotted using data from these observations to detect the amplitudes. The amplitudes and also the synodic rotation period of the 2012 apparition in clear-filtered photometry are discussed here.

Melillo, Frank J.



On Differential Photometric Reconstruction for Unknown, Isotropic BRDFs  

E-print Network

of photometric stereo, we show that just two measurements of spatial and temporal image derivatives, from unknown which it is observed. Photo- metric reconstruction methods seek to recover shape from images using source), they may be eliminated · M. Chandraker is with NEC Laboratories America, at Cupertino, CA 95014

O'Brien, James F.


On Differential Photometric Reconstruction for Unknown, Isotropic BRDFs  

E-print Network

of photometric stereo, we show that just two measurements of spatial and temporal image derivatives, from unknown which it is observed. Photo- metric reconstruction methods seek to recover shape from images using Laboratories America, at Cupertino, CA 95014. E-mail: · J. Bai and R. Ramamoorthi

O'Brien, James F.


10.1117/2.1201102.003507 Photometric design of  

E-print Network

of the human eye. LER values rarely go above 300lm/Wopt. The correlated color temperature (CCT) is another10.1117/2.1201102.003507 Photometric design of color-conversion LEDs Hilmi Volkan Demir, Talha- tometric figures-of-merit. One of them is the color rendering index (CRI), which measures how efficiently

Demir, Hilmi Volkan


Control model of photometric complex based on asynchronous finite automaton  

Microsoft Academic Search

A possibility is examined for synthesis of the control model of a photometric complex for investigation of the middle atmosphere night glow on the basis of asynchronous finite automata. The means for implementation of the suggested approach are examined. The advantage of this approach is expressed in the model flexibility.

Atanas Marinov Atanassov



Calibrating the Strömvil Photometric System by M 67 at VATT  

Microsoft Academic Search

For our observational program on stellar clusters to calibrate the Strömvil Photometric System (the four Strömgren u v b y and the three Vilnius P Z S filters), we use the Lennon Telescope (VATT) of the Vatican and Steward Observatories on Mt. Graham. We have observed the open cluster M 67 wherein much photometry both photoelectric and CCD already exists.

R. P. Boyle; A. G. Davis Philip; F. Smriglio; A. Dasgupta; A. Kazlauskas; V. Straizys



A photometric study of the Algol system Y Piscium  

Microsoft Academic Search

From the discussion of 417 photoelectric observations of this semi-detached Algol system, obtained in B and V during 82 nights in 1965–1971, the existence of a gas stream may be inferred for the following reasons: The scatter of the single observations is dependent on the orbital phase; the largest scatter occurs at the phases following both eclipses. The conventional photometric

K. Walter



Photometric CCD observations of four Pre-cataclysmic binary candidates  

NASA Astrophysics Data System (ADS)

We present preliminary results of differential photometric observations of Abell 65, HZ 9, GD 1401 and BPM 46460, obtained between September and December 2006 with the 42 cm telescope of the Cerro Armazones Observatory which belongs to the Universidad Catolica del Norte, Antofagasta. All four stars are close red dwarf/white dwarf binaries which could have formed be recent common envelope events. In two of the four cases we detected (or confirmed) significant variability. In one of them, the central star of a planetary nebula Abell 65, we confirmed the rather strong photometric variability with a period very near to 24 hours (Bond and Livio, 1990). In the white dwarf binary HZ9 we detected, for the first time, photometric variations with a period near 0.58 days which corresponds to the known orbital period (Lanning and Pesch, 1981; Stauffer, 1987). The amplitude of this variation is 0.08 mag, it probably refers to reflection of the white dwarf radiation on the surface of the red companion. - These observations are part of a larger on-going project which pretends to identify and to study pre-cataclysmic binaries by means of photometric and spectroscopic methods and to improve, this way, the hitherto poor statistics on the properties of these interesting stars.

Hinojosa, R.; Vogt, N.; Colque, Juan Pablo


Sidereal Photometric Astrometry as Efficient Initial Search for Spin Vector  

NASA Astrophysics Data System (ADS)

I describe how to use the Sidereal Photometric Astrometry method of spin vector determination (Drummond et al., 1988) to identify the specific plausible candidate combinations of sidereal periods and pole solution regions that are consistent with a lightcurve epoch data set, to use as initial inputs to the convex inversion method of shape determination (Kaasalainen et al., 2001).

Slivan, Stephen M.



Automated spectrophotometric analyzer for rapid single-point titration of seawater total alkalinity.  


An automated analyzer was developed to achieve fast, precise, and accurate measurements of seawater total alkalinity (AT) based on single-point titration and spectrophotometric pH detection. The single-point titration was carried out in a circulating loop, which allowed the titrant (hydrochloric acid and bromocresol green solution) and a seawater sample to mix at a constant volume ratio. The dissolved CO2 in the sample-titrant mixture was efficiently removed by an inline CO2 remover, which consists of a gas-permeable tubing (Teflon AF2400) submerged in a sodium hydroxide (NaOH) solution. The pH of the mixture was then measured with a custom-made spectrophotometric detection system. The analyzer was calibrated against multiple certified reference materials (CRMs) with different AT values. The analyzer features a sample throughput time of 6.5 min with high precision (±0.33-0.36 ?mol kg(-1); n = 48) and accuracy (-0.33 ± 0.99 ?mol kg(-1); n = 10). Intercomparison to a traditional open-cell AT titrator showed overall good agreement of 0.88 ± 2.03 ?mol kg(-1) (n = 22). The analyzer achieved excellent stability without recalibration over 11 days, during which time 320 measurements were made with a total running time of over 40 h. Because of its small size, low power consumption requirements, and its ability to be automated, the new analyzer can be adapted for underway and in situ measurements. PMID:23968512

Li, Quanlong; Wang, Fengzhen; Wang, Zhaohui Aleck; Yuan, Dongxing; Dai, Minhan; Chen, Jinshun; Dai, Junwei; Hoering, Katherine A



Calorimetry, activity, and micro-FTIR analysis of CO chemisorption, titration, and oxidation on supported Pt  

NASA Technical Reports Server (NTRS)

The value of in situ analysis on CO chemisorption, titration and oxidation over supported Pt catalysts using calorimetry, catalytic and micro-FTIR methods is illustrated using silica- and titania-supported samples. Isothermal CO-O and O2-CO titrations have not been widely used on metal surfaces and may be complicated if some oxide supports are reduced by CO titrant. However, they can illuminate the kinetics of CO oxidation on metal/oxide catalysts since during such titrations all O and CO coverages are scanned as a function of time. There are clear advantages in following the rates of the catalyzed CO oxidation via calorimetry and gc-ms simultaneously. At lower temperatures the evidence they provide is complementary. CO oxidation and its catalysis of CO oxidation have been extensively studied with hysteresis and oscillations apparent, and the present results suggest the benefits of a combined approach. Silica support porosity may be important in defining activity-temperature hysteresis. FTIR microspectroscopy reveals the chemical heterogeneity of the catalytic surfaces used; it is interesting that the evidence with regard to the dominant CO surface species and their reactivities with regard to surface oxygen for present oxide-supported Pt are different from those seen on graphite-supported Pt.

Sermon, Paul A.; Self, Valerie A.; Vong, Mariana S. W.; Wurie, Alpha T.



Chaotic dynamics of resting ventilatory flow in humans assessed through noise titration  

E-print Network

The mammalian ventilatory behavior exhibits nonlinear dynamics as reflected by certain nonlinearity or complexity indicators (e.g. correlation dimension, approximate entropy, Lyapunov exponents...) but this is not sufficient to determine its possible chaotic nature. To address this, we applied the noise titration technique, previously shown to discern and quantify chaos in short and noisy time series, to ventilatory flow recordings obtained in quietly breathing normal humans. Nine subjects (8 men and 1 woman, 24-42 yrs) were studied during 15-minute epochs of ventilatory steady-state (10.1 +/- 3.0 breaths/minute, tidal volume 0.63 +/- 0.2L). Noise titration applied to the unfiltered signals subsampled at 5 Hz detected nonlinearity in all cases (noise limit 20.2 +/- 12.5%). Noise limit values were weakly correlated to the correlation dimension and the largest Lyapunov exponent of the signals. This study shows that the noise titration approach evidences a chaotic dimension to the behavior of ventilatory flow over time in normal humans during tidal breathing.

Marc Wysocki; Marie-Noelle Fiamma; Christian Straus; Chi-Sang Poon; Thomas Similowski



Iodometric titration for determining the oxygen content of samples doped with Fe and Co  

NASA Astrophysics Data System (ADS)

Double iodometric titration is a method developed for high- Tc superconductivity. It has been widely used to determine the effective oxidation of copper and to figure out the oxygen content in a sample in the past years. If a sample is doped with some metals like iron and cobalt, these metal ions can interfere in experiment results. This is a major defect for iodometric titration. To solve this problem, we introduce ammonium hydrogen fluoride as a complex agent into the method. The agent can prevent the interference of ions of iron and cobalt. For samples LaBa 2Cu 3- xFe xO y and YBa 2Cu 3- xCo xO y, we determine the oxygen content by an improved double iodometric titration in which the ammonium hydrogen fluoride is used as an interference-free agent. For samples doped with a small amount of Fe or Co, experiment results agree well with those of other researchers. As to samples doped with a large amount of Fe or Co, we determine their values of oxygen content and the results are reasonable.

Chen, W. M.; Hong, W.; Geng, J. F.; Wu, X. S.; Ji, W.; Li, L. Y.; Qui, L.; Jin, X.



Statistical mechanical model of coupled transcription from multiple promoters due to transcription factor titration  

PubMed Central

Transcription factors (TFs) with regulatory action at multiple promoter targets is the rule rather than the exception, with examples ranging from the cAMP receptor protein (CRP) in E. coli that regulates hundreds of different genes simultaneously to situations involving multiple copies of the same gene, such as plasmids, retrotransposons, or highly replicated viral DNA. When the number of TFs heavily exceeds the number of binding sites, TF binding to each promoter can be regarded as independent. However, when the number of TF molecules is comparable to the number of binding sites, TF titration will result in correlation (“promoter entanglement”) between transcription of different genes. We develop a statistical mechanical model which takes the TF titration effect into account and use it to predict both the level of gene expression for a general set of promoters and the resulting correlation in transcription rates of different genes. Our results show that the TF titration effect could be important for understanding gene expression in many regulatory settings. PMID:24580252

Rydenfelt, Mattias; Cox, Robert Sidney; Garcia, Hernan; Phillips, Rob



Statistical mechanical model of coupled transcription from multiple promoters due to transcription factor titration  

NASA Astrophysics Data System (ADS)

Transcription factors (TFs) with regulatory action at multiple promoter targets is the rule rather than the exception, with examples ranging from the cAMP receptor protein (CRP) in E. coli that regulates hundreds of different genes simultaneously to situations involving multiple copies of the same gene, such as plasmids, retrotransposons, or highly replicated viral DNA. When the number of TFs heavily exceeds the number of binding sites, TF binding to each promoter can be regarded as independent. However, when the number of TF molecules is comparable to the number of binding sites, TF titration will result in correlation (“promoter entanglement”) between transcription of different genes. We develop a statistical mechanical model which takes the TF titration effect into account and use it to predict both the level of gene expression for a general set of promoters and the resulting correlation in transcription rates of different genes. Our results show that the TF titration effect could be important for understanding gene expression in many regulatory settings.

Rydenfelt, Mattias; Cox, Robert Sidney, III; Garcia, Hernan; Phillips, Rob



Determination of sulphuric acid in process effluent streams using sequential injection titration.  


Sulphuric acid in process effluent streams from an electrorefining copper plant was analysed with a sequential injection (SI) titration system using sodium hydroxide as titrant. In the proposed SI titration system a base titrant, acid analyte and base titrant zone were injected sequentially into a distilled water carrier stream in a holding coil and swept by flow reversal through a reaction coil to the detector. The base zones contained bromothymol blue as indicator and the endpoint was monitored spectrophotometrically at 620 nm. The influence of carrier stream flow rate, acid and base zone volumes and titrant concentration on the linear range of the method was studied to obtain an optimum. A linear relationship between peak width and logarithm of the acid concentration was obtained in the range 0.006-0.178 mol l(-1) of H(2)SO(4) for a NaOH concentration of 0.002 mol l(-1). The results obtained for the SI titration of process samples were in good agreement with a standard potentiometric method with an RSD<0.75% and a sample frequency of 23 samples h(-1). PMID:18967965

du Plessis, H; van Staden, J F



Asteroid taxonomic classification in the Gaia photometric system  

NASA Astrophysics Data System (ADS)

Aims:We evaluate the prospects of performing automatic taxonomic classification of asteroids in a proposed broad and medium band photometric system of Gaia. Methods: The study is based on asteroid colors from the Eight-Color Asteroid Survey (ECAS) and CCD spectra from the Small Mainbelt Asteroid Spectral Survey II (SMASSII). The success of the Gaia photometric systems for taxonomic classification is evaluated using supervised classification techniques and mean taxonomic class spectra in the Tholen and Bus&Binzel taxonomic systems. Our supervised classification method is based on rms differences between individual asteroid spectra and taxonomic mean spectra and provides probability estimates of membership in all taxonomic classes. Results: We find that both photometric systems of Gaia are able to discriminate between all of the twelve Tholen asteroid classes for noise-free data. The medium band system is able to discriminate between the majority of the 26 SMASSII asteroid classes in case of high quality photometric data. For both the Tholen and Bus & Binzel taxonomies we find that about 25% of the asteroids are spectrally more similar to another taxonomic class in a best-fit sense, though the differences within the three major complexes (C, S and X) are 1-10%. Conclusions: Among the two main existing taxonomies, the Gaia photometric system is found to be best suited for the Bus & Binzel taxonomy. The medium band system is the preferred system for all but the faintest objects. The classification method employed here results in more concentrated taxonomic class domains in principal component space, and mean taxonomic spectra that are formed from less divergent class members, than the case for the nominal classification systems. It provides statistical probability estimates for class memberships and naturally reflects the fact that asteroid spectral shapes form a continuum in principal component space.

Warell, J.; Lagerkvist, C.-I.




SciTech Connect

Supernova (SN) cosmology without spectroscopic confirmation is an exciting new frontier, which we address here with the Bayesian Estimation Applied to Multiple Species (BEAMS) algorithm and the full three years of data from the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SN). BEAMS is a Bayesian framework for using data from multiple species in statistical inference when one has the probability that each data point belongs to a given species, corresponding in this context to different types of SNe with their probabilities derived from their multi-band light curves. We run the BEAMS algorithm on both Gaussian and more realistic SNANA simulations with of order 10{sup 4} SNe, testing the algorithm against various pitfalls one might expect in the new and somewhat uncharted territory of photometric SN cosmology. We compare the performance of BEAMS to that of both mock spectroscopic surveys and photometric samples that have been cut using typical selection criteria. The latter typically either are biased due to contamination or have significantly larger contours in the cosmological parameters due to small data sets. We then apply BEAMS to the 792 SDSS-II photometric SNe with host spectroscopic redshifts. In this case, BEAMS reduces the area of the {Omega}{sub m}, {Omega}{sub {Lambda}} contours by a factor of three relative to the case where only spectroscopically confirmed data are used (297 SNe). In the case of flatness, the constraints obtained on the matter density applying BEAMS to the photometric SDSS-II data are {Omega}{sup BEAMS}{sub m} = 0.194 {+-} 0.07. This illustrates the potential power of BEAMS for future large photometric SN surveys such as Large Synoptic Survey Telescope.

Hlozek, Renee [Oxford Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom); Kunz, Martin [Department de physique theorique, Universite de Geneve, 30, quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland); Bassett, Bruce; Smith, Mat; Newling, James [African Institute for Mathematical Sciences, 68 Melrose Road, Muizenberg 7945 (South Africa); Varughese, Melvin [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, Cape Town, 7700 (South Africa); Kessler, Rick; Frieman, Joshua [The Kavli Institute for Cosmological Physics, The University of Chicago, 933 East 56th Street, Chicago, IL 60637 (United States); Bernstein, Joseph P.; Kuhlmann, Steve; Marriner, John [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Campbell, Heather; Lampeitl, Hubert; Nichol, Robert C. [Institute of Cosmology and Gravitation, Dennis Sciama Building Burnaby Road Portsmouth PO1 3FX (United Kingdom); Dilday, Ben [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Falck, Bridget; Riess, Adam G. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Sako, Masao [Department of Physics and Astronomy, University of Pennsylvania, 203 South 33rd Street, Philadelphia, PA 19104 (United States); Schneider, Donald P., E-mail: [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)



Planck 2013 results. VIII. HFI photometric calibration and mapmaking  

NASA Astrophysics Data System (ADS)

This paper describes the methods used to produce photometrically calibrated maps from the Planck High Frequency Instrument (HFI) cleaned, time-ordered information. HFI observes the sky over a broad range of frequencies, from 100 to 857 GHz. To obtain the best calibration accuracy over such a large range, two different photometric calibration schemes have to be used. The 545 and 857 GHz data are calibrated by comparing flux-density measurements of Uranus and Neptune with models of their atmospheric emission. The lower frequencies (below 353 GHz) are calibrated using the solar dipole. A component of this anisotropy is time-variable, owing to the orbital motion of the satellite in the solar system. Photometric calibration is thus tightly linked to mapmaking, which also addresses low-frequency noise removal. By comparing observations taken more than one year apart in the same configuration, we have identified apparent gain variations with time. These variations are induced by non-linearities in the read-out electronics chain. We have developed an effective correction to limit their effect on calibration. We present several methods to estimate the precision of the photometric calibration. We distinguish relative uncertainties (between detectors, or between frequencies) and absolute uncertainties. Absolute uncertainties lie in the range from 0.54% to 10% from 100 to 857 GHz. We describe the pipeline used to produce the maps from the HFI timelines, based on the photometric calibration parameters, and the scheme used to set the zero level of the maps a posteriori. We also discuss the cross-calibration between HFI and the SPIRE instrument on board Herschel. Finally we summarize the basic characteristics of the set of HFI maps included in the 2013 Planck data release.

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bertincourt, B.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Enßlin, T. A.; Eriksen, H. K.; Filliard, C.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Hanson, D.; Harrison, D.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Laureijs, R. J.; Lawrence, C. R.; Le Jeune, M.; Lellouch, E.; Leonardi, R.; Leroy, C.; Lesgourgues, J.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Maurin, L.; Mazzotta, P.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Moreno, R.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rusholme, B.; Santos, D.; Savini, G.; Scott, D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Techene, S.; Terenzi, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Yvon, D.; Zacchei, A.; Zonca, A.



Flame photometric determination of strontium in water  

USGS Publications Warehouse

Preliminary search of reported methods of Sr analysis revealed several investigations which have been made for the determination of Sr with the flame photometer, both at relatively low concentrations (0 to 50 ppm Sr) and at higher concentrations. Generally the procedures described involved measurement of Sr emission at either 460.7 mu or at 681 mu. There is disagreement among those reporting methods for Sr as to the preference of the one wavelength over the other. The 681 line (or band) seems to be preferred because of its greater reproducibility and relative freedom from interference. The 460.7 mu line, however, lies in the region of greater sensitivity of the photomultiplier tube, and hence for this reason is preferred by some. This is an advantage, of course, when determining Sr at very low concentrations. This investigation is concerned with determining the optimum conditions for the determination of Sr at low concentration levels in water samples. Early experimental work indicated a greater sensitivity for the 460.7 mu (hereafter designated as 461 mu) Sr line. Therefore, most of the subsequent work was based on a study of the effects of various other materials and conditions on the emission of Sr at this wavelength.

Skougstad, Marvin W.



Determination of NO/sub 2//sup -//NO/sub 3//sup -/ mixtures by titration with ascorbic acid  

SciTech Connect

The analysis of nitrite-nitrate mixtures by indirect titration with ascorbic acid performed before and after passage through a reducing Cd column is proposed and discussed with particular reference to experimental conditions, calculation scheme and concentration ranges.

Campanella, L.; Paoletti, A.M.



Effect of excess AgO and EDTA on the redox titration involved in potentiometric determination of plutonium  

Microsoft Academic Search

Attempts to carry out potentiometric determination of plutonium (by AgO-oxidation method) following the determination of thorium (by complexometric EDTA titration) gave positively biased irreproducible values of plutonium. In order to understand the factors leading to the erroneous values of plutonium, the effect of varying amounts of AgO and EDTA on redox [Fe(II)\\/K2Cr2O7] titration in the medium consisting of 1M H2SO4

S. P. Hasilkar; Keshav Chander; S. G. Marathe



Microanalytical Determination of Formaldehyde by Direct Titration with Hydroxylamine Using Interdigitated Microelectrode Array Biamperometric End-Point Indicator  

Microsoft Academic Search

.  ?An interdigitated microelectrode array (IDA) biamperometric titration is presented for the microdetermination of formaldehyde.\\u000a It is based on a direct titration of formaldehyde with hydroxylamine under the formation of formaldoxime. The released hydrogen\\u000a cations react with hydroxyl anions in 0.1?M NaOH. The interdigitated pair of two individually polarizable microelectrodes\\u000a serves as a biamperometric end-point indicator. Hydroxylamine together with dissolved free

Peter Tom?ík; Lea Mrafkova ´; Dušan Bustin



The Photometric Classification Server for Pan-STARRS1  

NASA Astrophysics Data System (ADS)

The Pan-STARRS1 survey is obtaining multi-epoch imaging in five bands (g P1 r P1 i P1 z P1 y 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, ?19% for stars, and ?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 × Median|z phot - z 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.

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



A Deep Photometric Survey of the Double Cluster h & ? Per  

NASA Astrophysics Data System (ADS)

We performed a deep multi-band photometric survey of the central regions of the young (˜13 Myr) and very rich double cluster, h & ? Persei, extending the membership down to the boundary region between stellar and sub-stellar domain (0.07M Sun ). We used data from CFHT (WIRCAM and MEGACAM) in I, Y, J, H and Ks bands. To select the candidate members we produced CMDs that we compared with the isochrones, and previous known members from photometric, spectroscopical, X-ray, proper motion, disk and H alpha emission studies. We selected several thousand candidate members in h & ? Persei, down to late M dwarfs in a field of view of 20 by 20 arcmin for each cluster.

Cardoso, Cátia V.; Moraux, Estelle; Bouvier, Jerôme


A Photometric Classification of the SAGE LMC Point Source Catalog  

NASA Astrophysics Data System (ADS)

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.

Marengo, Massimo; Antoniou, V.; SAGE Collaboration



Observational Tests to Detect Photometric Reverberation in H-alpha  

NASA Astrophysics Data System (ADS)

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.

Joner, Michael D.; Carroll, Carla



Photometric study of the pulsating, eclipsing binary OO Dra  

E-print Network

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. 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. It reveals that OO Dra could be a detached system with the less-massive secondary component nearly filling in its Roche lobe. By subtracting the eclipsing light changes from the data, we obtained the intrinsic pulsating light curves of the hotter and massive primary component. Frequency analysis of the residuals 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.

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



Photometric properties of resolved and unresolved magnetic elements  

E-print Network

We investigate the photometric signature of magnetic flux tubes in the solar photosphere. We developed two dimensional, static numerical models of isolated and clustered magnetic flux tubes. We investigated the emergent intensity profiles at different lines-of-sight for various spatial resolutions and opacity models. We found that both geometric and photometric properties of bright magnetic features are determined not only by the physical properties of the tube and its surroundings, but also by the particularities of the observations, including the line/continuum formation height, the spatial resolution and the image analyses techniques applied. We show that some observational results presented in the literature can be interpreted by considering bright magnetic features to be clusters of smaller elements, rather than a monolithic flux tube.

Serena Criscuoli; Mark Rast



Photometric and Kinematic Characterization of Tidal Dwarf Galaxy Candidates  

NASA Astrophysics Data System (ADS)

Tidal Dwarf Galaxies (TDG), or self-gravitating objects created from the tidal forces in interacting galaxies, have been found in several merging systems. This work will focus on identifying TDG candidates among a sample of Luminous and Ultraluminous Infrared Galaxies (U)LIRGs, where these interactions are occurring in order to study their formation and evolution. High angular resolution imaging from Hubble Space Telescope (HST) in B, I and H band will be used to detect these sources. Photometric measurements of these regions compared to Stellar Synthesis Population models will allow us to roughly estimate the age and the mass. Using complementary optical Integral Field Spectroscopy we will be able to explore the physical, kinematical and dynamical properties in TDGs. We present preliminary photometric results for IRAS 0857+3915, as an example of the study that will be held for the entire sample of (U)LIRGs.

Miralles-Caballero, D.; Colina, L.; Arribas, S.



SciTech Connect

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.

Koch, David G.; Borucki, William J.; Lissauer, Jack J. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Basri, Gibor; Marcy, Geoffrey [Department of Astronomy, University of California-Berkeley, Berkeley, CA 94720 (United States); Batalha, Natalie M. [Department of Physics and Astronomy, San Jose State University, San Jose, CA 95192 (United States); Brown, Timothy M. [Las Cumbres Observatory Global Telescope, Goleta, CA 93117 (United States); Caldwell, Douglas; DeVore, Edna; Jenkins, Jon [SETI Institute, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Christensen-Dalsgaard, Joergen [Aarhus University, DK-8000, Aarhus C (Denmark); Cochran, William D. [McDonald Observatory, University of Texas at Austin, Austin, TX 78712 (United States); Dunham, Edward W. [Lowell Observatory, Flagstaff, AZ 86001 (United States); Gautier, Thomas N. [Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109 (United States); Geary, John C.; Latham, David W. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Gilliland, Ronald L. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Gould, Alan [Lawarence Hall of Science, University of California-Berkeley, Berkeley, CA 94720 (United States); Kondo, Yoji [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Monet, David [United States Naval Observatory, Flagstaff, AZ 86002 (United States)], E-mail: (and others)



The photometric period of the recurrent Nova T Pyxidis  

NASA Technical Reports Server (NTRS)

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.

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



The wavelength dependence and an interpretation of the photometric parameters of Mars  

NASA Technical Reports Server (NTRS)

The photometric function developed by Meador and Weaver has been used with photometric data from the bright desert areas of Mars to determine the wavelength dependence of the three photometric parameters of that function and to provide some predictions about the physical properties of the surface. Knowledge of the parameters permits the brightness of these areas of Mars to be determined for scattering geometry over the wavelength range of 0.45 to 0.70 micrometer. The changes in the photometric parameters with wavelength are shown to be consistent with qualitative theoretical predictions, and the predictions of surface properties are shown to be consistent with conditions that might exist in these regions of Mars. The photometric function is shown to have good potential as a diagnostic tool for the determination of surface properties, and the consistency of the behavior of the photometric parameters is shown to be good support for the validity of the photometric function.

Weaver, W. R.; Meador, W. E.



A photometric and spectroscopic study of BG Canis Minoris  

Microsoft Academic Search

The photometric and spectroscopic analysis presented here has revealed new observational features in the Intermediate Polar BG CMi. We have found a strong variability of the dominant light pulsations, rotational (913s) and orbital (3.23hr), on a timescale of years. Variations in the amplitude of the spin pulsation with epoch generally appear to be anti-correlated with that of the orbital modulation

D. de Martino; M. Mouchet; J. M. Bonnet-Bidaud; R. Vio; S. R. Rosen; K. Mukai; T. Augusteijn; M. A. Garlick



Detailed Spectroscopic and Photometric Analysis of DQ White Dwarfs  

E-print Network

We present an analysis of spectroscopic and photometric data for cool DQ white dwarfs based on improved model atmosphere calculations. In particular, we revise the atmospheric parameters of the trigonometric parallax sample of Bergeron et al.(2001), and discuss the astrophysical implications on the temperature scale and mean mass, as well as the chemical evolution of these stars. We also analyze 40 new DQ stars discovered in the first data release of the Sloan Digital Sky Survey.

P. Dufour; P. Bergeron; G. Fontaine



A multi-site photometric campaign on V709 Cas  

NASA Astrophysics Data System (ADS)

We present preliminary results from a multisite photometric campaign on the intermediate polar V709 Cas carried out between Sept. 22 and Oct. 2, 2000. The combined white light data show a strong flickering and the presence of variability at the first harmonic of the beat (317.9 s) and a weak signal at the 312.8 s spin periods. We also detect a 5.347 h orbital variability likely due to a partial eclipse of the accretion disc.

de Martino, D.; Silvotti, R.; González Pérez, J. M.; Kalytis, R.; Janulis, R.; Jiang, X. J.; Oswalt, T.; Carlson, G.; Silvestri, N.; Bonnet-Bidaud, J. M.; Matt, G.; Mouchet, M.; Mukai, K.



Photometric properties of magnetic elements: resolved and unresolved features  

E-print Network

We investigate, by numerical simulations, the photometric signature of magnetic flux tubes in the solar photosphere. We show that the observed contrast profiles are determined not only by the physical properties of the tube and its surroundings, but also by the peculiarities of the observations, including the line/continuum formation height and the spatial and spectral resolution. The aim is to understand these contributions well enough so that multi-wavelength observations can begin to disentangle them.

Serena Criscuoli



Photometric analysis of Galactic Stellar Clusters in VVV Survey  

NASA Astrophysics Data System (ADS)

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).

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



Microdensitometer errors: Their effect on photometric data reduction  

NASA Technical Reports Server (NTRS)

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.

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



Spectroscopic and Photometric Observations of the Close Binary BPM 71214  

NASA Astrophysics Data System (ADS)

We have obtained photometric and spectroscopic observations of the close DA plus dMe binary BPM 71214. We have updated the ephemeris of the system and observed ellipsoidal variations of the secondary star, which establishes that the red dwarf is nearly filling its Roche lobe. Our new observations suggest that BPM 71214, along with EC 13471-1258, may belong to a new class of hibernating novae.

Kawka, Adela; Vennes, Stéphane



Automated Selection of AGNs from SDSS Photometric Data: Initial Results  

NASA Astrophysics Data System (ADS)

We have applied ClassX, an oblique decision tree classifier optimized for astronomical analysis (McGLynn et al. ApJ, 616, December 1, 2004; Suchkov & Hanisch, ApJ, 612, 437, 2004) to the huge, homogeneous multicolor imaging data base of the Sloan Digital Sky Survey (SDSS), training the software on a subset of ˜ 30,000 SDSS objects whose nature is precisely known via spectroscopy. We find that the software, using photometric data only, correctly classifies a very large fraction of the objects with existing SDSS spectra, both galactic and extragalactic. ClassX also accurately predicts the redshifts of galaxies and active galactic nuclei (AGN) in SDSS. Thus ClassX can probably address most of the highly diverse areas of astronomy addressed by SDSS, and should be especially powerful at accurately recognizing very rare objects solely through their photometric properties. The surface density of AGNs selected by ClassX to r ˜ 19 is in reasonable agreement with that quoted by SDSS. When ClassX is exercised on the photometric data fainter than the SDSS spectroscopic limit, the inferred surface density rises sharply, as expected. We discuss our measurement of the surface density as a function of apparent magnitude, which is unique due to the homogeneity of both SDSS and the classifier. Finally, the ability of the classifier to accurately constrain the redshifts of huge numbers (ultimately ˜ 107) of AGNs in the photometric data base provides new insights into the evolution of the AGN luminosity function with cosmic time. While our results are still very preliminary, it is clear that a very large population of relatively low luminosity AGNs appears in the 0.2 < z < 0.4 range.

Suchkov, A. A.; Hanisch, R. J.; Margon, B.



Some photometric techniques for atmosphereless solar system bodies.  


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

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



PhotoRApToR: PHOTOmetric Research APplication TO Redshifts  

NASA Astrophysics Data System (ADS)

PhotoRApToR (PHOTOmetric Research APplication TO Redshifts) solves regression and classification problems and is specialized for photo-z estimation. PhotoRApToR offers data table manipulation capabilities and 2D and 3D graphics tools for data visualization; it also provides a statistical report for both classification and regression experiments. The code is written in Java; the machine learning model is in C++ to increase the core execution speed.

Brescia, Massimo



Exhausting the information: novel Bayesian combination of photometric redshift PDFs  

NASA Astrophysics Data System (ADS)

The estimation and utilization of photometric redshift probability density functions (photo-z PDFs) have become increasingly important over the last few years and currently there exist a wide variety of algorithms to compute photo-z's, each with their own strengths and weaknesses. In this paper, we present a novel and efficient Bayesian framework that combines the results from different photo-z techniques into a more powerful and robust estimate by maximizing the information from the photometric data. To demonstrate this, we use a supervised machine learning technique based on random forest, an unsupervised method based on self-organizing maps, and a standard template-fitting method but can be easily extended to other existing techniques. We use data from the DEEP2 survey and the Sloan Digital Sky Survey to explore different methods for combining the predictions from these techniques. By using different performance metrics, we demonstrate that we can improve the accuracy of our final photo-z estimate over the best input technique, that the fraction of outliers is reduced, and that the identification of outliers is significantly improved when we apply a naïve Bayes classifier to this combined information. Our more robust and accurate photo-z PDFs will allow even more precise cosmological constraints to be made by using current and future photometric surveys. These improvements are crucial as we move to analyse photometric data that push to or even past the limits of the available training data, which will be the case with the Large Synoptic Survey Telescope.

Carrasco Kind, Matias; Brunner, Robert J.



ESO & NOT photometric monitoring of the Cloverleaf quasar  

NASA Astrophysics Data System (ADS)

The Cloverleaf quasar, H1413+117, has been photometrically monitored at ESO (La Silla, Chile) and with the NOT (La Palma, Spain) during the period 1987--1994. All good quality CCD frames have been successfully analysed using two independent methods (i.e. an automatic image decomposition technique and an interactive CLEAN algorithm). The photometric results from the two methods are found to be very similar, and they show that the four lensed QSO images vary significantly in brightness (by up to 0.45 mag), nearly in parallel. The lightcurve of the $D$ component presents some slight departures from the general trend which are very likely caused by micro-lensing effects. Upper limits, at the 99% confidence level, of 150 days on the absolute value for the time delays between the photometric lightcurves of this quadruply imaged variable QSO, are derived. This is unfortunately too large to constrain the lens model but there is little doubt that a better sampling of the lightcurves should allow to accurately derive these time delays. Pending a direct detection of the lensing galaxy (position and redshift), this system thus constitutes another good candidate for a direct and independent determination of the Hubble parameter. Based on observations collected at the European Southern Observatory (La Silla, Chile) and with the Nordic Optical Telescope (La Palma, Spain). Table 1. Logbook for the ESO and NOT observations together with photometric results for the Cloverleaf quasar. This long table can be accessed on the WWW at the URL address:}

Ostensen, R.; Remy, M.; Lindblad, P. O.; Refsdal, S.; Stabell, R.; Surdej, J.; Barthel, P. D.; Emanuelsen, P. I.; Festin, L.; Gosset, E.; Hainaut, O.; Hakala, P.; Hjelm, M.; Hjorth, J.; Hutsemekers, D.; Jablonski, M.; Kaas, A. A.; Kristen, H.; Larsson, S.; Magain, P.; Pettersson, B.; Pospieszalska-Surdej, A.; Smette, A.; Teuber, J.; Thomsen, B.; van Drom, E.



Molecular Dynamics Simulation of the Titration of Polyoxocations in Aqueous Solution  

SciTech Connect

The aqueous complex ion Al30O8(OH)56(H2O)26 18+(Al30) has a variety of bridging and terminal amphoteric surface functional groups which deprotonate over a pH range of 4–7. Their relative degree of protonation is calculated here from a series of molecular dynamics simulations in what appear to be the first molecular dynamics simulations of an acidometric titration. In these simulations, a model M30O8(OH)56(H2O)26 18+ ion is embedded in aqueous solution and titrated with hydroxide ions in the presence of a charge-compensating background of perchlorate ions. Comparison with titration of a model M13O4(OH)24(H2O)12 7+ reveals that the M30 ion is more acidic than the M13 ion due to the presence of acidic nH2O functional groups. The higher acidities of the functional groups on the M30 ion appear to result from enhanced hydration. Metal–oxygen bond lengths are calculated for the ion in solution, an isolated ion in the gas phase, and in its crystalline hydrate sulfate salt. Gas-phase and crystalline bond lengths do not correlate well with those calculated in solution. The acidities do not relate in any simple way to the number of metals coordinating the surface functional group or the M-O bond length. Moreover, the calculated acidity in solution does not correlate with proton affinities calculated for the isolated ion in the absence of solvent. It is concluded that the search for simple indicators of structure–reactivity relationships at the level of individual reactive sites faces major limitations, unless specific information on the hydration states of the functional groups is available.

Rustad, James R.



Non-damaging laser therapy of the macula: Titration algorithm and tissue response  

NASA Astrophysics Data System (ADS)

Retinal photocoagulation typically results in permanent scarring and scotomata, which limit its applicability to the macula, preclude treatments in the fovea, and restrict the retreatments. Non-damaging approaches to laser therapy have been tested in the past, but the lack of reliable titration and slow treatment paradigms limited their clinical use. We developed and tested a titration algorithm for sub-visible and non-damaging treatments of the retina with pulses sufficiently short to be used with pattern laser scanning. The algorithm based on Arrhenius model of tissue damage optimizes the power and duration for every energy level, relative to the threshold of lesion visibility established during titration (and defined as 100%). Experiments with pigmented rabbits established that lesions in the 50-75% energy range were invisible ophthalmoscopically, but detectable with Fluorescein Angiography and OCT, while at 30% energy there was only very minor damage to the RPE, which recovered within a few days. Patients with Diabetic Macular Edema (DME) and Central Serous Retinopathy (CSR) have been treated over the edematous areas at 30% energy, using 200?m spots with 0.25 diameter spacing. No signs of laser damage have been detected with any imaging modality. In CSR patients, subretinal fluid resolved within 45 days. In DME patients the edema decreased by approximately 150?m over 60 days. After 3-4 months some patients presented with recurrence of edema, and they responded well to retreatment with the same parameters, without any clinically visible damage. This pilot data indicates a possibility of effective and repeatable macular laser therapy below the tissue damage threshold.

Palanker, Daniel; Lavinsky, Daniel; Dalal, Roopa; Huie, Philip



Calibration of LSST Instrumental and Atmospheric Photometric Passbands  

SciTech Connect

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.

Burke, David L.; /SLAC; Axelrod, T.; /Arizona U., Astron. Dept. - Steward Observ.; Barrau, Aurelien; Baumont, Sylvain; /LPSC, Grenoble; Blondin, Stephane; /Marseille, CPPM; Claver, Chuck; /NOAO, Tucson; Gorecki, Alexia; /LPSC, Grenoble; Ivezic, Zeljko; Jones, Lynne; /Washington U., Seattle, Astron. Dept.; Krabbendam, Victor; Liang, Ming; Saha, Abhijit; /NOAO, Tucson; Smith, Allyn; /Austin Peay State U.; Smith, R.Chris; /Cerro-Tololo InterAmerican Obs.; Stubbs, Christopher W.; /Harvard-Smithsonian Ctr. Astrophys.



Measuring the transition to homogeneity with photometric redshift surveys  

NASA Astrophysics Data System (ADS)

We study the possibility of detecting the transition to homogeneity using photometric redshift catalogues. Our method is based on measuring the fractality of the projected galaxy distribution, using angular distances, and relies only on observable quantities. It thus provides a way to test the cosmological principle in a model-independent unbiased way. We have tested our method on different synthetic inhomogeneous catalogues and shown that it is capable of discriminating some fractal models with relatively large fractal dimensions, in spite of the loss of information due to the radial projection. We have also studied the influence of the redshift bin width, photometric redshift errors, bias, non-linear clustering, and surveyed area on the angular homogeneity index H2(?) in a ? cold dark matter cosmology. The level to which an upcoming galaxy survey will be able to constrain the transition to homogeneity will depend mainly on the total surveyed area and the compactness of the surveyed region. In particular, a Dark Energy Survey (DES)-like survey should be able to easily discriminate certain fractal models with fractal dimensions as large as D2 = 2.95. We believe that this method will have relevant applications for upcoming large photometric redshift surveys, such as DES or the Large Synoptic Survey Telescope.

Alonso, D.; Bueno Belloso, A.; Sánchez, F. J.; García-Bellido, J.; Sánchez, E.




SciTech Connect

Magnitude differences obtained from speckle imaging are used in combination with other data in the literature to place the components of binary star systems on the H-R diagram. Isochrones are compared with the positions obtained, and a best-fit isochrone is determined for each system, yielding both masses of the components as well as an age range consistent with the system parameters. Seventeen systems are studied, 12 of which were observed with the 0.6 m Lowell-Tololo Telescope at Cerro Tololo Inter-American Observatory and six of which were observed with the WIYN 3.5 m Telescope (The WIYN Observatory is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories) at Kitt Peak. One system was observed from both sites. In comparing photometric masses to mass information from orbit determinations, we find that the photometric masses agree very well with the dynamical masses, and are generally more precise. For three systems, no dynamical masses exist at present, and therefore the photometrically determined values are the first mass estimates derived for these components.

Davidson, James W. [Department of Physics and Astronomy, University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606-3390 (United States); Baptista, Brian J. [Department of Astronomy, Indiana University, 727 East 3rd Street, Bloomington, IN 47405-7105 (United States); Horch, Elliott P. [Department of Physics, Southern Connecticut State University, 501 Crescent Street, New Haven, CT 06515 (United States); Franz, Otto [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Van Altena, William F. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)], E-mail:, E-mail:, E-mail:, E-mail:, E-mail:



Detector driver systems and photometric estimates for RIMAS  

NASA Astrophysics Data System (ADS)

The Rapid infrared IMAger-Spectrometer (RIMAS) is a rapid gamma-ray burst afterglow instrument that will provide photometric and spectroscopic coverage of the Y, J, H, and K bands. RIMAS separates light into two optical arms, YJ and HK, which allows for simultaneous coverage in two photometric bands. RIMAS utilizes two 2048 x 2048 pixel Teledyne HgCdTe (HAWAII-2RG) detectors along with a Spitzer Legacy Indium- Antimonide (InSb) guiding detector in spectroscopic mode to position and keep the source on the slit. We describe the software and hardware development for the detector driver and acquisition systems. The HAWAII- 2RG detectors simultaneously acquire images using Astronomical Research Cameras, Inc. driver, timing, and processing boards with two C++ wrappers running assembly code. The InSb detector clocking and acquisition system runs on a National Instruments cRIO-9074 with a Labview user interface and clocks written in an easily alterable ASCII file. We report the read noise, linearity, and dynamic range of our guide detector. Finally, we present RIMAS's estimated instrument efficiency in photometric imaging mode (for all three detectors) and expected limiting magnitudes. Our efficiency calculations include atmospheric transmission models, filter models, telescope components, and optics components for each optical arm.

Toy, Vicki L.; Kutyrev, Alexander S.; Lyness, Eric I.; Muench, Marius; Robinson, Frederick D.; Lotkin, Gennadiy N.; Capone, John I.; Veilleux, Sylvain; Moseley, Samuel H.; Gehrels, Neil A.; Vogel, Stuart N.



Photometric and polarimetric observations and model simulations of (216) Kleopatra  

NASA Astrophysics Data System (ADS)

We performed photometric and polarimetric observations, on November 8 and 9, 1999, of an M-type main belt asteroid, (216) Kleopatra by using the HBS spectropolarimeter installed at Dodaira observatory, National Astronomical Observatory of Japan (NAOJ). Photometric amplitude of lightcurve in the V band was 0.12 mag, and the averaged degree of polarization was -1.01±0.1%. It seems that the polarimetric data might also show a slight change in the degree of polarization ( ~0.2%) at the second minimum of the photometric lightcurve, but we could not confirm that the feature was real because of the large errors of data. With the assumption that the surface is uniform, we have carried out lightcurve simulations based on shape models by Ostro et al. (2000), Tanga et al. (2001) and Roche binary (Cellino et al., 1985). The results of simulations were compared to the configurations of lightcurves which had been obtained at different 4 geometric positions (1980, 1982, 1987 and 1999). The model by Cellino et al. (1985) reproduced almost all the data points without the 1987 observations within ~0.05 mag., which is the best result among the 3 models. The model by Tanga et al. (2001) well reproduced the lightcurves, but failed in reproducing the 1982 amplitude (difference ?diff ~ 0 2 mag.). We also confirmed that the model by Ostro et al. (2000) could not explain the observed lightcurves.

Takahashi, S.; Shinokawa, K.; Yoshida, F.; Mukai, T.; Ip, W. H.; Kawabata, K.



Exhausting the Information: Novel Bayesian Combination of Photometric Redshift PDFs  

E-print Network

The estimation and utilization of photometric redshift (photo-z) PDFs has become increasingly important over the last few years. Primarily this is because of the prominent role photo-z PDFs play in enabling photometric survey data to be used to make cosmological constraints, especially when compared to single estimates. Currently there exist a wide variety of algorithms to compute photo-z's, each with their own strengths and weaknesses. In this paper, we present a novel and efficient Bayesian framework that combines the results from different photo-z techniques into a more powerful and robust estimate by maximizing the information from the photometric data. To demonstrate this we use a supervised machine learning technique based on prediction trees and a random forest, an unsupervised method based on self organizing maps and a random atlas, and a standard template fitting method but can be easily extend to other existing techniques. We use data from the DEEP2 survey and more than $10^6$ galaxies from the SDSS...

Kind, M Carrasco



Estimating the organic acid contribution to coastal seawater alkalinity by potentiometric titrations in a closed cell.  


This paper examines the performance of a previously reported, closed cell, potentiometric titration technique [J.M. Hernández-Ayón, S.L. Belli, A. Zirino, Anal. Chim. Acta 394 (1999) 101] for the simultaneous determination of pH, total inorganic carbon (TCO2), total alkalinity (TA), and organic alkalinity (OA) in coastal seawater samples. A novel interpretation of the titration data, as recently proposed by Hernández-Ayón et al. [J.M. Hernández-Ayón, A. Zirino, A.G. Dickson, T. Camiro-Vagas, E. Valenzuela-Espinoza, Limnol. Oceanogr.: Methods 5 (2007) 225] who applied it to waters of unusually high organic matter content, was applied here to fjord surface waters collected over the duration of a phytoplankton bloom. The parameters pH and TCO2--combined with knowledge of boric, phosphate and silicate species concentrations--allowed calculation of all inorganic species that contributed to TA. This inorganic alkalinity term was then subtracted from TA to produce an estimation of OA. Although the OA values obtained were very small (2-22+/-3 micromol L(-1)), they showed a reproducible trend over time in two simultaneous experiments. The organic acids that may have contributed to OA were characterised in back titrations of acidified and CO2-stripped samples with CO2-free NaOH. Two classes of organic titratable species, with pK(a) values around 4.0+/-0.2 and 9.1+/-0.2 were detected. The first occurred in concentrations that co-varied linearly (r2=0.75) with protein-like fluorescence, indicating a marine biological source, but were only weakly correlated (r2=0.46) to OA. By contrast, Class 2 organic species were not significantly correlated to any fluorescence component of either marine or terrestrial origin but were linearly correlated to OA (r2=0.69). These new results reveal that the method proposed by Hernández-Ayón et al. [J.M. Hernández-Ayón, A. Zirino, A.G. Dickson, T. Camiro-Vagas, E. Valenzuela-Espinoza, Limnol. Oceanogr.: Methods 5 (2007) 225] for estimating OA can provide a powerful and hitherto unused tool for analysing DOM dynamics and sources in most coastal environments, i.e. as a complement to the more widely used optical tools. PMID:18558111

Muller, François L L; Bleie, Bjørn



New challenges for pharmaceutical formulations and drug delivery systems characterization using isothermal titration calorimetry.  


Long viewed as the 'method of choice' for characterizing thermodynamics and stoichiometry of molecular interactions, with high sensitivity, isothermal titration calorimetry (ITC) has been applied to many areas of pharmaceutical analysis. This review highlights ITC employment to measure binding thermodynamics and their use for pharmaceutical formulations and drug delivery system characterization particularly cyclodextrin-guest interactions, investigation of micellar-based systems, polyelectrolytes, nucleic acid interactions with multivalent cations and the optimization of DNA targeting and delivery. Furthermore, the potential of ITC for the characterization of different functionalities carried by nanoparticles as well as their interaction with living systems was outlined. PMID:18617012

Bouchemal, Kawthar



Inclusion complex of benzocaine and ?-cyclodextrin: 1H NMR and isothermal titration calorimetry studies  

NASA Astrophysics Data System (ADS)

The supramolecular structure of the inclusion complex of ?-cyclodextrin with benzocaine in aqueous solution has been investigated by 1H NMR spectroscopy and isothermal titration nanocalorimetry (ITC). Analysis of 1H NMR data by continuous variation method indicates that the benzocaine: ?-cyclodextrin inclusion complex occurs and has a 1:1 stoichiometry. Rotating frame NOE spectroscopy (ROESY) was used to ascertain the solution geometry of the host-guest complex which indicates that the benzocaine molecule was included with the aromatic ring into the cyclodextrin cavity. Although the affinity of benzocaine for cyclodextrin is relatively high, the association constant cannot be measured using ITC due to the low solubility of benzocaine in water.

Mic, Mihaela; P?rn?u, Adrian; Bogdan, Mircea; Turcu, Ioan



Complexometric titration of calcium in the presence of larger amounts of magnesium.  


A simple and accurate titrimetric determination of calcium in the presence of larger amounts of magnesium is proposed. Calcium is extracted into a small volume of organic solvent as its glyoxal-bis(2-hydroxyanil) complex, and the calcium is titrated with EGTA. The end-point is sharp, and occurs when the red colour of the organic layer vanishes. This method has been successfully applied to the determination of calcium in sea-water with an error less than 0.1%. PMID:18960309

Tsunogai, S; Nishimura, M; Nakaya, S



Photometric Recovery of Crowded Stellar Fields Observed with HST/WFPC2 and the Effects of Confusion Noise on the Extragalactic Distance Scale  

E-print Network

We explore the limits of photometric reductions of crowded stellar fields observed with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope. Two photometric procedures, based on the DoPHOT and DAOPHOT/ALLFRAME programs are tested, and the effects of crowding, complex sky background and cosmic-ray contamination are discussed using an extensive set of artificial star simulations. As a specific application of the results presented in this paper, we assess the magnitude of photometric biases on programs aimed at finding Cepheids and determining distances. We find that while the photometry in individual images can be biased too bright by up to 0.2 mag in the most crowded fields due to confusion noise, the effects on distance measurements based on Cepheid variables are insignificant, less than 0.02 mag (1% in distance) even in the most problematic cases. This result, which is at odds with claims recently surfaced in the literature, is due to the strict criteria applied in the selection of the variable stars, and the photometric cross checks made possible by the availability of multiple exposures in different filters which characterizes Cepheid observations.

Laura Ferrarese; N. A. Silbermann; Jeremy R. Mould; Peter B. Stetson; Abhijit Saha; Wendy L. Freedman; Robert C. Kennicutt, Jr



A single-beam titration method for the quantification of open-path Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

This study introduced a quantitative method that can be used to measure the concentration of analytes directly from a single-beam spectrum of open-path Fourier Transform Infrared Spectroscopy (OP-FTIR). The peak shapes of the analytes in a single-beam spectrum were gradually canceled (i.e., "titrated") by dividing an aliquot of a standard transmittance spectrum with a known concentration, and the sum of the squared differential synthetic spectrum was calculated as an indicator for the end point of this titration. The quantity of a standard transmittance spectrum that is needed to reach the end point can be used to calculate the concentrations of the analytes. A NIST traceable gas standard containing six known compounds was used to compare the quantitative accuracy of both this titration method and that of a classic least square (CLS) using a closed-cell FTIR spectrum. The continuous FTIR analysis of industrial exhausting stack showed that concentration trends were consistent between the CLS and titration methods. The titration method allowed the quantification to be performed without the need of a clean single-beam background spectrum, which was beneficial for the field measurement of OP-FTIR. Persistent constituents of the atmosphere, such as NH3, CH4 and CO, were successfully quantified using the single-beam titration method with OP-FTIR data that is normally inaccurate when using the CLS method due to the lack of a suitable background spectrum. Also, the synthetic spectrum at the titration end point contained virtually no peaks of analytes, but it did contain the remaining information needed to provide an alternative means of obtaining an ideal single-beam background for OP-FTIR.

Sung, Lung-Yu; Lu, Chia-Jung




SciTech Connect

We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end, we compare the LFs obtained using photometric redshifts from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising {approx}4800 galaxies. We find that for z {<=} 2.0, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of the CFHTLS comprising {approx}386,000 galaxies to compute the LF of the combined fields and directly estimate the error in the parameters based on the field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by {approx}0.7 mag from z {approx} 1.8 to z {approx} 0.3, while the characteristic density {phi}* increases by a factor of {approx}4 in the same redshift interval. We use the galaxy classification provided by the template fitting program used to compute photometric redshifts and split the sample into galaxy types. We find that these Schechter parameters evolve differently for each galaxy type, an indication that their evolution is a combination of several effects: galaxy merging, star formation quenching, and mass assembly. All these results are compatible with those obtained by different spectroscopic surveys such as VVDS, DEEP2, and zCosmos, which reinforces the fact that photometric redshifts can be used to study galaxy evolution, at least for the redshift bins adopted so far. This is of great interest since future very large imaging surveys containing hundreds of millions of galaxies will allow us to obtain important precise measurements to constrain the evolution of the LF and to explore the dependence of this evolution on morphology and/or color helping constrain the mechanisms of galaxy evolution.

Ramos, B. H. F.; Pellegrini, P. S.; Da Costa, L. N.; Maia, M. A. G.; Ogando, R. L. C.; De Simoni, F. [Observatorio Nacional, Rua Gal. Jose Cristino 77, Rio de Janeiro, RJ 20921-400 (Brazil); Benoist, C.; Makler, M. [Laboratorio Interinstitucional de e-Astronomia-LIneA, Rua Gal. Jose Cristino 77, Rio de Janeiro, RJ 20921-400 (Brazil); Mesquita, A. A., E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Universidade Federal do Rio de Janeiro, Observatorio do Valongo, Ladeira do Pedro Antonio, 43 Rio de Janeiro, RJ 20080-090 (Brazil)



Complexometric Titrations: Competition of Complexing Agents in the Determination of Water Hardness with EDTA  

NASA Astrophysics Data System (ADS)

The competition of complexing agents for the same metal ion and the formation of colored metal-ion complexes is demonstrated with the use of an overhead projector. This demonstration can be used to emphasize both the relevance of the relative values of formation constants in the complexation of metal cations and the applicability of complexometric titrations in quantitative chemical analysis. The demonstration is based on the traditional determination of water hardness in which EDTA is used as the titrant that complexes Mg2+ and Ca2+ ions. The color change that signals the end of the titration represents the successful removal of the Mg2+ ions from the metallochromic indicator Calmagite. This removal is possible because the value of the formation constant of the [Mg(EDTA)]2- complex is about 3 orders of magnitude greater than that corresponding to the [Mg(Calmagite)]- complex. The color change from wine-red (metal-bound indicator) to blue (unbound indicator) can be seen clearly in a large classroom with the use of overhead projection.

Yappert, M. Cecilia; Dupre, Donald B.



Energetics of genome ejection from phage revealed by isothermal titration calorimetry  

NASA Astrophysics Data System (ADS)

It has been experimentally shown that ejection of double-stranded DNA from phage is driven by internal pressure reaching tens of atmospheres. This internal pressure is partially responsible for delivery of DNA into the host cell. While several theoretical models and simulations nicely describe the experimental data of internal forces either resisting active packaging or equivalently favoring spontaneous ejection, there are no direct energy measurements available that would help to verify how quantitative these theories are. We performed direct measurements of the enthalpy responsible for DNA ejection from phage ?, using Isothermal Titration Calorimetry. The phage capsids were ``opened'' in vitro by titrating ? into a solution with LamB receptor and the enthalpy of DNA ejection process was measured. In his way, enthalpy stored in ? was determined as a function of packaged DNA length comparing wild-type phage ? (48.5 kb) with a shorter ?-DNA length mutant (37.7 kb). The temperature dependence of the ejection enthalpy was also investigated. The values obtained were in good agreement with existing models and provide a better understanding of ds- DNA packaging and release mechanisms in motor-packaged viruses (e.g., tailed bacteriophages, Herpes Simplex, and adenoviruses).

Jeembaeva, Meerim; Jonsson, Bengt; Castelnovo, Martin; Evilevitch, Alex



Higher order inclusion complexes and secondary interactions studied by global analysis of calorimetric titrations.  


This paper investigates the use of isothermal titration calorimetry (ITC) as a tool for studying molecular systems in which weaker secondary interactions are present in addition to a dominant primary interaction. Such systems are challenging since the signal pertaining to the stronger primary interaction tends to overshadow the signal from the secondary interaction. The methodology presented here enables a complete and precise thermodynamic characterization of both the primary and the weaker secondary interaction, exemplified by the binding of ?-cyclodextrin to the primary and secondary binding sites of the bile salt glycodeoxycholate. Global regression analysis of calorimetric experiments at various concentrations and temperatures provide a precise determination of ?H, ?G°, and ?C(p) for both binding sites in glycodeoxycholate (K1 = 5.67 ± 0.05 × 10(3) M(-1), K2 = 0.31 ± 0.02 × 10(3) M(-1)). The results are validated by a (13)C NMR titration and negative controls with a bile salt with no secondary binding site (glycocholate) (K = 2.96 ± 0.01 × 10(3) M(-1)). The method proved useful for detailed analysis of ITC data and may strengthen its use as a tool for studying molecular systems by advanced binding models. PMID:22292412

Schönbeck, Christian; Holm, René; Westh, Peter



Hydration and Lyotropic Melting of Amphiphilic Molecules: A Thermodynamic Study Using Humidity Titration Calorimetry.  


The hydration of the lipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and of the cationic detergent dodecyltrimethylammonium bromide (DTAB) has been studied by means of isothermal titration calorimetry (ITC), gravimetry, and infrared (IR) spectroscopy. During the experiments films of the amphiphiles are perfused by an inert gas of variable relative humidity. The measurement of adsorption heats using ITC represents a new adaptation of adsorption calorimetry which has been called the humidity titration technique. This method yields the partial molar enthalpy of water upon adsorption. It is found to be endothermic with respect to the molar enthalpy of water on condensation for the water molecules which interact directly with the headgroups of POPC and DTAB. Consequently, the spontaneous hydration of the amphiphiles is entropy driven in an aqueous environment. IR spectroscopy shows that hydration is accompanied by the increase in the conformational and/or motional freedom of the amphiphilic molecules upon water binding. In particular, a lyotropic chain melting transition is induced at a certain characteristic relative humidity. This event is paralleled by the adsorption of water. The corresponding exothermic adsorption heat is consumed completely (POPC) or partially (DTAB) by the hydrocarbon chains upon melting. Differential scanning calorimetry was used as an independent method to determine transition enthalpies of the amphiphiles at a definite hydration degree. Water binding onto the headgroups is discussed in terms of hydrogen bonding and polar interactions. The adsorption isotherms yield a number of approximately 2.6 tightly bound water molecules per POPC and DTAB molecule. Copyright 1999 Academic Press. PMID:10607439

Binder; Kohlstrunk; Heerklotz



Characterization of molecularly imprinted polymers using a new polar solvent titration method.  


A new method of characterizing molecularly imprinted polymers (MIPs) was developed and tested, which provides a more accurate means of identifying and measuring the molecular imprinting effect. In the new polar solvent titration method, a series of imprinted and non-imprinted polymers were prepared in solutions containing increasing concentrations of a polar solvent. The polar solvent additives systematically disrupted the templation and monomer aggregation processes in the prepolymerization solutions, and the extent of disruption was captured by the polymerization process. The changes in binding capacity within each series of polymers were measured, providing a quantitative assessment of the templation and monomer aggregation processes in the imprinted and non-imprinted polymers. The new method was tested using three different diphenyl phosphate imprinted polymers made using three different urea functional monomers. Each monomer had varying efficiencies of templation and monomer aggregation. The new MIP characterization method was found to have several advantages. To independently verify the new characterization method, the MIPs were also characterized using traditional binding isotherm analyses. The two methods appeared to give consistent conclusions. First, the polar solvent titration method is less susceptible to false positives in identifying the imprinting effect. Second, the method is able to differentiate and quantify changes in binding capacity, as measured at a fixed guest and polymer concentration, arising from templation or monomer aggregation processes in the prepolymerization solution. Third, the method was also easy to carry out, taking advantage of the ease of preparing MIPs. PMID:24895277

Song, Di; Zhang, Yagang; Geer, Michael F; Shimizu, Ken D



Titration of amlodipine to higher doses: a comparison of Asian and Western experience  

PubMed Central

In this retrospective analysis, data pooled from two Phase III/IV open-label Asian studies were used to quantify the additional blood pressure efficacy achieved when titrating amlodipine from 5 mg to 10 mg in mild/moderate hypertensive patients, and compared to data pooled from three Western studies. The primary efficacy end point was the change from baseline in sitting systolic blood pressure (SBP) and diastolic blood pressure (DBP) to the specified time point (4–8 weeks, depending on the trial). For the Asian analysis (n=174), both mean SBP and DBP were significantly decreased at the final visit (SBP ?13.3 mmHg, 95% confidence interval [CI] ?15.5 to ?11.0; DBP ?9.2 mmHg, 95% CI ?10.6 to ?7.8; both P<0.0001). These results were similar to the Western analysis (n=369; SBP ?11.5 mmHg, 95% CI ?13.1 to ?10.0; DBP ?6.3, 95% CI ?7.1 to ?5.5; both P<0.0001). In summary, titration of amlodipine from 5 mg to 10 mg significantly decreased both SBP and DBP in Asian patients with mild-to-moderate hypertension. PMID:24235839

Kario, Kazuomi; Robbins, Jeffery; Jeffers, Barrett W



Influenza virus titration, antigenic characterization, and serological methods for antibody detection.  


This chapter describes some commonly used methods of influenza virus titration, antigenic characterization, and serological methods by antibody detection. These methods are essential not only for virus characterization but also for identifying new antigenic variants, vaccine strain selection, and sero-epidemiologic studies of influenza virus transmission and prevalence. Virus titration methods such as the hemagglutination assay, 50% egg or tissue culture infectious dose, and plaque assay are employed to determine the amount of virus particles in a sample. The hemagglutination inhibition assay is a reliable, relatively simple and inexpensive technique to antigenically characterize isolates of influenza viruses. Serological methods such as virus neutralization and hemagglutination inhibition are the fundamental tools used in sero-epidemiologic studies of influenza virus transmission and prevalence and in the evaluation of vaccine immunogenicity. While serological methods rarely yield an early diagnosis of acute influenza virus infection, well-timed, paired acute, and convalescent serum samples may establish the diagnosis of a recent influenza infection even when attempts to detect the virus are negative. PMID:22528152

Klimov, Alexander; Balish, Amanda; Veguilla, Vic; Sun, Hong; Schiffer, Jarad; Lu, Xiuhua; Katz, Jacqueline M; Hancock, Kathy



Cluster membership probabilities from proper motions and multi-wavelength photometric catalogues. I. Method and application to the Pleiades cluster  

NASA Astrophysics Data System (ADS)

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 statistically sound multivariate analysis techniques to fully exploit their scientific information content. Proper motions in particular are, as expected, critical for the correct separation of contaminants. The methodology presented here is ready for application in data sets that include more dimensions, such as radial and/or rotational velocities, spectral indices, and variability. Membership probability catalogs for the DANCe Pleiades data are only available at the CDS via anonymous ftp to ( or via

Sarro, L. M.; Bouy, H.; Berihuete, A.; Bertin, E.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Barrado, D.; Solano, E.



Optimizing growth hormone replacement therapy by dose titration in hypopituitary adults.  


Although growth hormone (GH) replacement therapy is increasingly utilized in the management of adult hypopituitary patients, optimum dosing schedules are poorly defined. The use of weight-based or surface area-based dosing may result in overtreatment, and individual variation in susceptibility on the basis of gender and other factors is now being recognized. To optimize GH replacement and to explore further gender differences in susceptibility, we used a dose titration regimen, starting at the initiation of GH replacement therapy, in 50 consecutive adult-onset hypopituitary patients, and compared the results with those in 21 patients previously treated using a weight-based regimen. Titrated patients commenced GH 0.8 IU/day subcutaneously (0.4 IU/day if hypertensive or glucose tolerance impaired). Serum insulin-like growth factor I (IGF-I) was measured at 0, 2, 4, 6, 8, 10, and 12 weeks in all patients. Serum IGF binding protein 3 and acid labile subunit were measured at the same time points in 17 patients (8 male, 9 female). Patients were reviewed every 4 weeks and the dose of GH increased, if necessary, to achieve a serum IGF-I level between the median and the upper end of the age-related reference range. There was no significant difference between mean serum IGF-I at 2 and 4 weeks, or between 6 and 8 weeks, indicating that the full effects of a change in dose are evident within 2 weeks of that change. Maintenance doses were significantly higher in females than males [1.2 (0.8-2.0) vs. 0.8 (0.4-1.6) IU/day; median (range); P < 0.0001], and the median time to achieve maintenance dose was significantly shorter in males [4 (2-12) vs. 9 (2-26) weeks; P < 0.0001]. Median maintenance dose was lower overall than in a group of 21 patients initially commenced on GH using a weight-based dosing schedule, with subsequent adjustment of dose during clinical follow-up [1.5 (0.4-3.2) IU/day; P = 0.02]. Reduction in waist measurement and waist to hip ratio at 6 and 12 months was similar in females (P < 0.001) and males (P < 0.01). Well-being improved significantly after 3 months of GH therapy (14.2 +/- 5.9 vs. 7.4 +/- 4.5 SD; P < 0.0001), and there were no gender differences. Adult Growth Hormone Deficiency Assessment (AGHDA) scores at 6 months were similar to maintenance scores in patients commenced on weight-based regimens. Measurements of ALS and IGFBP-3 added no useful extra information to IGF-I in managing the dose titration. The practical scheme outlined for dose titration of GH replacement resulted in rapid achievement of lower maintenance doses than those achieved using conventional weight-based regimens without loss of efficacy. It was particularly important in female patients who demonstrated decreased overall sensitivity to GH and required higher doses to achieve the same effects as males. This constitutes the first report of a uniform titration regimen based on a defined target range of serum IGF-I in a large patient cohort. PMID:9814468

Drake, W M; Coyte, D; Camacho-Hübner, C; Jivanji, N M; Kaltsas, G; Wood, D F; Trainer, P J; Grossman, A B; Besser, G M; Monson, J P



Application of rapid, electrochemical Flash Titration to total acidity and alkalinity determinations in buffers, foods, and beverages.  


A new technique (Flash Titration) for the determination of total acidity and total alkalinity was applied to food and beverage analysis. Requiring no liquid titrants, Flash Titration is a technique made possible through microfabrication of electrochemical components on a silicon chip. Acidic or basic titrant was generated electrochemically at a noble-metal electrode that intimately surrounded an ion-selective, field-effect transistor pH sensor. As acid or base was generated through electrolysis, sample alkalinity or acidity, respectively, was neutralized in the immediate vicinity of the electrode. Through diffusion, a zone comprising a gradient of partially to totally neutralized sample expanded from the generating electrode into the volume element sensed by the nearby pH sensor. An analysis of the pH signal versus time revealed an end point inflection at an elapsed time related to the total alkalinity or acidity of the sample. End point times were typically a few seconds. In this paper, Flash Titration was applied to the analysis of a variety of samples, including juices, soft drinks, wines, and food products. The differences between the results obtained by the Flash Titration method and a commonly used conventional volumetric method were less than 2% in most food products tested. Analysis costs were reduced both through time saving and reduction or elimination of hazardous liquid titrant disposal, by the use of the Flash Titration method. PMID:15493680

Wen, Xiaowen; Herdan, Janet; West, Steven; Kinkade, Denise; Vilissova, Nadejda; Anderson, Matthew



Photodigitizing procedures  

NASA Astrophysics Data System (ADS)

This report documents procedures and programs for efficiently running the Photo Digitizing System at the Naval Biodynamics Laboratory. Procedures have been tested and have been found to be effective. Any future acquisitions of programs or changes to current programs should be incorporated in these procedures. On-going research programs use high speed instrumentation cameras to record the motion of test subjects during biodynamic experiments. The films are digitized and the 3-dimensional motion is reconstructed and analyzed. Experimental research is performed to determine the effects of aircraft crashes, ship motion, vibration, aircraft ejection and parachute opening forces on the health and performance of Navy personnel.

Kilgore, P. D.; Gottbrath, J. H.



Whipple Procedure  


... Research Genetics - Kern Lab Early Detection- Goggins Lab Sol Goldman Center Discussion Board The Whipple Procedure Also ... the Vesalius Trust . Goldman Center funding from the Sol Goldman Charitable Trust . Johns Hopkins Medicine 401 North ...


A Volume-limited Photometric Survey of 114 ? Doradus Candidates  

NASA Astrophysics Data System (ADS)

We have carried out a photometric survey of a complete, volume-limited sample of ? Doradus candidates. The sample was extracted from the Hipparcos catalog and consists of 114 stars with colors and absolute magnitudes within the range of known ? Doradus stars and that also lie within a specified volume of 266,600 pc3. We devoted one year of observing time with our T12 0.8 m automatic photometric telescope to acquire nightly observations of the complete sample of stars. From these survey observations, we identify 37 stars with intrinsic variability of 0.002 mag or more. Of these 37 variables, 8 have already been confirmed as ? Doradus stars in our earlier papers; we scheduled the remaining 29 variables on our T3 0.4 m automatic telescope to acquire more intensive observations over the next two years. As promising new ? Doradus candidates were identified from the photometry, we obtained complementary spectroscopic observations of each candidate with the Kitt Peak coudé feed telescope. Analysis of our new photometric and spectroscopic data reveals 15 new ? Doradus variables (and confirms two others), 8 new ? Scuti variables (and confirms one other), and 3 new variables with unresolved periodicity. Therefore, of the 114 ? Doradus candidates in our volume-limited sample, we find 25 stars that are new or previously known ? Doradus variables. This results in an incidence of 22% for ? Doradus variability among candidate field stars for this volume of the solar neighborhood. The corresponding space density of ? Doradus stars in this volume of space is 0.094 stars per 103 pc3 or 94 stars per 106 pc3. We provide an updated list of 86 bright, confirmed, ? Doradus field stars.

Henry, Gregory W.; Fekel, Francis C.; Henry, Stephen M.



Probable swirls detected as photometric anomalies in Oceanus Procellarum  

NASA Astrophysics Data System (ADS)

Images of the lunar nearside obtained by telescopes of Maidanak Observatory (Uzbekistan) and Simeiz Observatory (Crimea, Ukraine) equipped with Canon CMOS cameras and Sony CCD LineScan camera were used to study photometric properties of the lunar nearside in several spectral bands. A wide range of lunar phase angles was covered, and the method of phase ratios to assess the steepness of the phase function at different phase angles is applied. We found several areas with photometric anomalies in the south-west portion of the lunar disk that we refer to as Oceanus Procellarum anomalies. The areas being unique on the lunar nearside do not obey the inverse correlation between albedo and phase-curve slope, demonstrating high phase-curve slopes at intermediate albedo. Low-Sun images acquired with Lunar Orbiter IV and Apollo-16 cameras do not reveal anomalous topography of the regions, at least for scales larger than several tens of meters. The areas also do not have any thermal inertia, radar (70 and 3.8 cm), magnetic, or chemical/mineral peculiarities. On the other hand they exhibit a polarimetric signature that we interpret to be due to the presence of a porous regolith upper layer consisting of dust particles. The anomalies may be interpreted as regions of very fresh shallow regolith disturbances caused by impacts of meteoroid swarms consisting of rather small impactors. This origin is similar to one of the hypotheses for the origin of lunar swirls like the Reiner-? formation. The photometric difference between the shallow and pervasive (Reiner-? class) swirls is that the latter appear to have a significant amount of immature soils in the upper surface layers.

Shkuratov, Yu.; Kaydash, V.; Gerasimenko, S.; Opanasenko, N.; Velikodsky, Yu.; Korokhin, V.; Videen, G.; Pieters, C.



Intrinsic alignments of group and cluster galaxies in photometric surveys  

NASA Astrophysics Data System (ADS)

Intrinsic alignments of galaxies have been shown to contaminate weak gravitational lensing observables on linear scales, r > 10 h-1 Mpc, but studies of alignments in the non-linear regime have thus far been inconclusive. We present an estimator for extracting the intrinsic alignment signal of galaxies around stacked clusters of galaxies from multiband imaging data. Our estimator removes the contamination caused by galaxies that are gravitationally lensed by the clusters and scattered in redshift space due to photometric redshift uncertainties. It uses posterior probability distributions for the redshifts of the galaxies in the sample and it is easily extended to obtain the weak gravitational lensing signal while removing the intrinsic alignment contamination. We apply this algorithm to groups and clusters of galaxies identified in the Sloan Digital Sky Survey `Stripe 82' co-added imaging data over ˜150 deg2. We find that the intrinsic alignment signal around stacked clusters in the redshift range 0.1 < z < 0.4 is consistent with zero. In terms of the tidal alignment model of Catelan et al., we set joint constraints on the strength of the alignment and the bias of the lensing groups and clusters on scales between 0.1 and 10 h-1 Mpc, b_LC_1? _crit = -2_{-14}^{+14} × 10^{-4}. This constrains the contamination fraction of alignment to lensing signal to the range between [ - 18, 23] per cent below scales of 1 h-1 Mpc at 95 per cent confidence level, and this result depends on our photometric redshift quality and selection criteria used to identify background galaxies. Our results are robust to the choice of photometric band in which the shapes are measured (i and r) and to centring on the Brightest Cluster Galaxy or on the geometrical centre of the clusters.

Chisari, Nora Elisa; Mandelbaum, Rachel; Strauss, Michael A.; Huff, Eric M.; Bahcall, Neta A.



High-precision gravimetric coulometry using the silver-perchloric acid coulometer: Titration of arsenious oxide with electrogenerated iodine.  


High-precision gravimetric coulometry with a silver-perchloric acid coulometer is evaluated as an alternative to the conventional titrimetric method. The loss of weight (caused by electrolytic dissolution) of a highly pure silver anode in series with the cathode of a conventional constant-current titration system is measured and related to the number of equivalents of substance titrated. The precision of the method is determined by titrations of the Standard Reference Material 83C arsenious oxide (99.99% pure) with electrogenerated iodine, using biamperometric end-point detection. Depending on the size of the sample, an ultimate precision of 25 ppm is obtained. The assay for 0.5-g samples of the SRM material is 99.993(9) +/- 0.002(5)% purity. PMID:18962104

Newton, C M



Probing dark energy with lensing magnification in photometric surveys.  


I present an estimator for the angular cross correlation of two tracers of the cosmological large-scale structure that utilizes redshift information to isolate separate physical contributions. The estimator is derived by solving the Limber equation for a reweighting of the foreground tracer that nulls either clustering or lensing contributions to the cross correlation function. Applied to future photometric surveys, the estimator can enhance the measurement of gravitational lensing magnification effects to provide a competitive independent constraint on the dark energy equation of state. PMID:24580685

Schneider, Michael D




SciTech Connect

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.

Kuzio de Naray, Rachel [Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575 (United States); Zagursky, Matthew J.; McGaugh, Stacy S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)], E-mail:, E-mail:, E-mail:



Photometric stellar parameters for asteroseismology and Galactic studies  

E-print Network

Asteroseismology has the capability of delivering stellar properties which would otherwise be inaccessible, such as radii, masses and thus ages of stars. When coupling this information with classical determinations of stellar parameters, such as metallicities, effective temperatures and angular diameters, powerful new diagnostics for both stellar and Galactic studies can be obtained. I review how different photometric systems and filters carry important information on classical stellar parameters, the accuracy at which those parameters can be derived, and summarize some of the calibrations available in the literature for late-type stars. Recent efforts in combining classical and asteroseismic parameters are discussed, and the unique- ness of their intertwine is highlighted.

Casagrande, Luca



Infrared Imaging, Spectroscopic, and Photometric Studies of Comets  

NASA Technical Reports Server (NTRS)

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 acquired more than 3000 256x256 images totaling nearly two gigabytes of data detailing the near-IR development of the impact sites of the S-L9 fragments on Jupiter. These data were obtained using the University of Rochester Imaging IR Camera at the cassegrain focus of the 92" at WIRO. The WIRO data set covers 8 days and is, to our knowledge, one of the most extensive observational records of the S-L/Jupiter encounter obtained by any ground-based telescope. This program benefitted from the compilation during these last few months of an upgrade to the data acquisition program at WIRO with support of this NASA contract.

Gehrz, Robert D.



A photometric function for diffuse reflection by particulate materials  

NASA Technical Reports Server (NTRS)

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.

Meador, W. E.; Weaver, W. R.



Photometric Survey for Brown Dwarfs in Orion's Belt  

NASA Astrophysics Data System (ADS)

This is a preliminary report on our VRIJHK survey centered on the region around Orion's belt. We observed ˜9 deg2 at VRI with the MOSAIC camera and ˜7 deg2 at JHK with the NEWFIRM camera on the KPNO 4m telescope. Our survey will produce a list of photometrically selected candidate very low-mass stars and brown dwarfs with masses down to 10 Jupiter masses (MJ). We discuss the status of our data reductions, and preliminary work on the NEWFIRM photometry.

Sherry, W. H.; Walter, F. M.; Brittain, S. D.; Kim, J. S.; Merritt, A.




SciTech Connect

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.

Shaw, Michael S.; Romani, Roger W. [Department of Physics/KIPAC, Stanford University, Stanford, CA 94305 (United States); Filippenko, Alexei V.; Cenko, S. Bradley; Li, Weidong [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)



Proton induced methyl group shifts in gaseous xylenium ions. Distinguishing isomers by gas-phase titration  

NASA Astrophysics Data System (ADS)

The differences in the gas-phase basicities (GBs) of isomers can be used for a semi-quantitative mixture analysis. For this "gas-phase titration" method, the mixture of isomers is completely protonated in the external ion source of a FT-ion cyclotron resonance spectrometry (ICR) spectrometer and undergoes selective, stepwise deprotonation by reactions with appropriate bases within the FT-ICR cell. This method is demonstrated by the analysis of a mixture of three isomeric alkylpyridines differing in GB by 4 kJ mol-1. "Gas-phase titration" is employed to detect the isomerization of gaseous para-xylenium ions XpH+ into the more stable ortho and meta isomers XoH+ and XmH+ by 1,2-methyl shifts around the aromatic ring. Strongly exoenergetic protonation of para-xylene Xp in the external ion source by chemical ionization (CI) (methane) and gas-phase titration of the resulting XH+ after transfer into the FT-ICR cell reveals isomerization of XpH+ into a mixture of <= 15 mol% XpH+, 25 ± 3 mol% XoH+, and 60 ± 4 mol% XmH+. The degree of isomerization depends clearly on the exoenergicity of the initial protonation and is significantly reduced for XH+ ions generated by CI (dimethyl ether). This effect is confirmed by an investigation of the controlled protonation of Xp by selected proton donors AH+ (A = C2H5CN, CH3OH, C6H6, C3H6, H2O, C2H4) in the FTICR cell. This study shows that the chemical nature of A is also important for the degree of isomerization. The results are explained convincingly by assuming isomerization of the XpH+ ions through multiple 1,2-methyl shifts within a long lived ion/molecule complex [A...H+Xp], formed by proton transfer from AH+ to Xp. The rearrangement is driven by the excess energy of the complex as a result of exothermic proton transfer and electrostatic activation of the complex, and competes with the dissociation of the excited complex.

Büker, Heinz-Hermann; Grützmacher, Hans-Friedrich; Crestoni, Maria Elisa; Ricci, Andreina



Photometric Variability of Be/X-ray-Pulsar Binaries in the SMC  

E-print Network

We have studied the photometric variability of ten SMC Be/X-ray pulsars using MACHO and OGLE-II data. For some of these systems we have found periodic behavior, including orbital outbursts and/or nonradial pulsations (NRP) of the Be star. For others we were unable to identify any clear photometric periodicity, although their longterm light curves show significant structure. We present periodograms, phase dispersion minimization (PDM) variances, and folded light curves for the systems which exhibit periodic photometric variability.

P. C. Schmidtke; A. P. Cowley



Time-resolved photometric and spectroscopic analysis of the luminous Ap star HD103498  

Microsoft Academic Search

We present the results of the photometric and spectroscopic monitoring of the luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using a three-channel fast photometer attached to the 1.04-m optical telescope at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital. The photometric data from five nights in 2007 show a clear signature of

S. Joshi; T. Ryabchikova; O. Kochukhov; M. Sachkov; S. K. Tiwari; N. K. Chakradhari; N. Piskunov



Improved methylene blue two-phase titration method for determining cationic surfactant concentration in high-salinity brine.  


The methylene blue (MB) two-phase titration method is a rapid and efficient method for determining the concentrations of anionic surfactants. The point at which the aqueous and chloroform phases appear equally blue is called Epton's end point. However, many inorganic anions, e.g., Cl(-), NO3(-), Br(-), and I(-), can form ion pairs with MB(+) and interfere with Epton's end point, resulting in the failure of the MB two-phase titration in high-salinity brine. Here we present a method to extend the MB two-phase titration method for determining the concentration of various cationic surfactants in both deionized water and high-salinity brine (22% total dissolved solid). A colorless end point, at which the blue color is completely transferred from the aqueous phase to the chloroform phase, is proposed as titration end point. Light absorbance at the characteristic wavelength of MB is measured using a spectrophotometer. When the absorbance falls below a threshold value of 0.04, the aqueous phase is considered colorless, indicating that the end point has been reached. By using this improved method, the overall error for the titration of a permanent cationic surfactant, e.g., dodecyltrimethylammonium bromide, in deionized (DI) water and high-salinity brine is 1.274% and 1.322% with limits of detection (LOD) of 0.149 and 0.215 mM, respectively. Compared to the traditional acid-base titration method, the error of this improved method for a switchable cationic surfactant, e.g., tertiary amine surfactant (Ethomeen C12), is 2.22% in DI water and 0.106% with LOD of 0.369 and 0.439 mM, respectively. PMID:25365626

Cui, Leyu; Puerto, Maura; López-Salinas, José L; Biswal, Sibani L; Hirasaki, George J



Thermodynamic and kinetic properties of interpolymer complexes assessed by isothermal titration calorimetry and surface plasmon resonance.  


Interpolymer complexes (IPCs) formed between complimentary polymers in solution have shown a wide range of applications from drug delivery to biosensors. This work describes the combined use of isothermal titration calorimetry and surface plasmon resonance to investigate the thermodynamic and kinetic processes during hydrogen-bonded interpolymer complexation. Varied polymers that are commonly used in layer-by-layer coatings and pharmaceutical preparations were selected to span a range of chemical functionalities including some known IPCs previously characterized by other techniques, and other polymer combinations with unknown outcomes. This work is the first to comprehensively detail the thermodynamic and kinetic data of hydrogen bonded IPCs, aiding understanding and detailed characterization of the complexes. The applicability of the two techniques in determining thermodynamic, gravimetric and kinetic properties of IPCs is considered. PMID:25186562

Bizley, Samuel C; Williams, Adrian C; Khutoryanskiy, Vitaliy V



Isolation and titration of dengue viruses by the mosquito inoculation technique.  


Mosquito inoculation is a highly sensitive technique for isolation and titration of dengue virus (DENV) from sera, human tissues, wild animals, or mosquitoes. It has been under utilized since it was described 40 years ago because most dengue laboratories do not have access to an insectary to rear mosquitoes. This technique requires good eye-hand coordination while doing manipulation under a stereoscopic microscope, and extensive practice is needed to become proficient at inoculating mosquitoes. Following inoculation, mosquitoes are held for 10 days to allow dengue virus to replicate and disseminate to tissues throughout the mosquitoes. They are then harvested and examined for the presence of viral antigens in head tissue by either immunofluorescence assay (IFA) or PCR (polymerase chain reaction). The mosquito infectious dose 50 (MID50) is calculated using the method of Reed and Muench to quantitate the virus. This method can be used for other arboviruses as well as for dengue. PMID:24696328

Choy, Milly M; Gubler, Duane J



Canadian Tire Money: An Analogy for Use When Discussing Weak Acid Strong Base Titrations  

NASA Astrophysics Data System (ADS)

A simple analogy can often provide an instructor with a means of helping students to understand an unfamiliar concept. An analogy involving money can be particularly helpful as most students have experience in dealing with a range of financial transactions in their everyday lives. In this article, use is made of the practice of one well-known Canadian retail chain in returning to its customers a small percentage of an item's purchase price in the form of imitation bank notes that can subsequently be spent in the chain's stores. An analogy is drawn between this practice and the determination of the pKa of a weak acid by titrating it with a strong base, taking into account the hydrolysis of the anion produced.

Last, Arthur M.



DNA heats up : Energetics of genome ejection from phage revealed by isothermal titration calorimetry  

E-print Network

Most bacteriophages are known to inject their double-stranded DNA into bacteria upon receptor binding in an essentially spontaneous way. This downhill thermodynamic process from the intact virion toward the empty viral capsid plus released DNA is made possible by the energy stored during active packaging of the genome into the capsid. Only indirect measurements of this energy have been available until now using either single-molecule or osmotic suppression techniques. In this paper, we describe for the first time the use of isothermal titration calorimetry to directly measure the heat released (or equivalently the enthalpy) during DNA ejection from phage lambda, triggered in solution by a solubilized receptor. Quantitative analyses of the results lead to the identification of thermodynamic determinants associated with DNA ejection. The values obtained were found to be consistent with those previously predicted by analytical models and numerical simulations. Moreover, the results confirm the role of DNA hydration in the energetics of genome confinement in viral capsids.

Meerim Jeembaeva; B. Jönsson; Martin Castelnovo; Alex Evilevitch



An accurate method of iodometric titration for determining oxygen content of superconducting cuprates  

NASA Astrophysics Data System (ADS)

There are three problems existing in double iodometric titration. First, the calculating equation is too rough to obtain accurate results. Second, an error comes from iodine adsorbed by CuI. Third, when a sample is doped with iron-like elements, iron interferes with this method. The above problems were solved as following. We adopted a new equation, which may modify copper valence p by 4% and oxygen content by 0.02. To reduce the experimental error KSCN was added to displace the adsorbed iodine on the CuI. NH 4HF 2 was introduced to prevent the interference of Fe. Our experiment results show that by adding NH 4HF 2 the modification of oxygen content increases when Fe content increases.

Chen, W. M.; Chen, N. L.; Lam, C. C.; Chen, J.; Wu, X. S.; Zhang, X.; Chen, D. B.; Jin, X.


Complexation of ?-cyclodextrin with a gemini surfactant studied by isothermal titration microcalorimetry and surface tensiometry.  


We report on the inclusion complex formation of ?-cyclodextrin (?CD) with a cocogem surfactant (counterion-coupled gemini surfactant; (bis(4-(2-alkyl)benzenesulfonate)-Jeffamine salt, abbreviated as ABSJ), studied by isothermal titration calorimetry (ITC) and surface tension (SFT) measurements. We measured the critical micelle concentration (cmc) of ABSJ in water by the two experimental techniques in the temperature range 283-343 K, and determined the thermodynamic parameters of the complex formation directly by ITC and indirectly by the SFT. The stoichiometry (N), the binding constant (K), and the enthalpy of complexation were determined, and the Gibbs free energy and the entropy term were calculated from the experimental data. A novel method is presented for the determination of N and K by using surface tensiometry. PMID:24846443

Benk?, Mária; Király, László A; Puskás, Sándor; Király, Zoltán



Membrane surface-charge titration probed by gramicidin A channel conductance.  

PubMed Central

We manipulate lipid bilayer surface charge and gauge its influence on gramicidin A channel conductance by two strategies: titration of the lipid charge through bulk solution pH and dilution of a charged lipid by neutral. Using diphytanoyl phosphatidylserine (PS) bilayers with CsCl aqueous solutions, we show that the effects of lipid charge titration on channel conductance are masked 1) by conductance saturation with Cs+ ions in the neutral pH range and 2) by increased proton concentration when the bathing solution pH is less than 3. A smeared charge model permits us to separate different contributions to the channel conductance and to introduce a new method for "bilayer pKa" determination. We use the Gouy-Chapman expression for the charged surface potential to obtain equilibria of protons and cations with lipid charges. To calculate cation concentration at the channel mouth, we compare different models for the ion distribution, exact and linearized forms of the planar Poisson-Boltzmann equation, as well as the construction of a "Gibbs dividing surface" between salt bath and charged membrane. All approximations yield the intrinsic pKain of PS lipid in 0.1 M CsCl to be in the range 2.5-3.0. By diluting PS surface charge at a fixed pH with admixed neutral diphytanoyl phosphatidylcholine (PC), we obtain a conductance decrease in magnitude greater than expected from the electrostatic model. This observation is in accord with the different conductance saturation values for PS and PC lipids reported earlier (, Biochim. Biophys. Acta. 552:369-378) and verified in the present work for solvent-free membranes. In addition to electrostatic effects of surface charge, gramicidin A channel conductance is also influenced by lipid-dependent structural factors. PMID:9746520

Rostovtseva, T K; Aguilella, V M; Vodyanoy, I; Bezrukov, S M; Parsegian, V A



Quantifying high-affinity binding of hydrophobic ligands by isothermal titration calorimetry.  


A fast and reliable quantification of the binding thermodynamics of hydrophobic high-affinity ligands employing a new calorimetric competition experiment is described. Although isothermal titration calorimetry is the method of choice for a quantitative characterization of intermolecular interactions in solution, a reliable determination of a dissociation constant (K(D)) is typically limited to the range 100 ?M > K(D) > 1 nM. Interactions displaying higher or lower K(D) values can be assessed indirectly, provided that a suitable competing ligand is available whose K(D) falls within the directly accessible affinity window. This established displacement assay, however, requires the high-affinity ligand to be soluble at high concentrations in aqueous buffer and, consequently, poses serious problems in the study of protein binding involving small-molecule ligands dissolved in organic solvents--a familiar case in many drug-discovery projects relying on compound libraries. The calorimetric competition assay introduced here overcomes this limitation, thus allowing for a detailed thermodynamic description of high-affinity receptor-ligand interactions involving poorly water-soluble compounds. Based on a single titration of receptor into a dilute mixture of the two competing ligands, this competition assay provides accurate and precise values for the dissociation constants and binding enthalpies of both high- and moderate-affinity ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation and high-affinity protein-inhibitor interactions, and explore its potential and limitations with the aid of simulations and statistical analyses. PMID:23130786

Krainer, Georg; Broecker, Jana; Vargas, Carolyn; Fanghänel, Jörg; Keller, Sandro



[Molecular dynamics method for proteins with ionization-conformation coupling and equilibrium titration].  


A new realization of the constant-pH molecular dynamics simulation method is proposed. Molecular dynamics simulation is performed for a protein in the most probable ionization microstate of the current conformation taking into account the potential of mean force of protein molecule in the water-proton bath in equilibrium titration conditions (MD-pH-ET). It is shown that: 1) the optimal one is the simulation of the protein in the most probable ionization for a given conformation, taking into account the correction ionization potential of mean force, which results in the librium ensemble of ionization states; 2) new method MD-pH-ET allow one to carry out an optimization of protein structure and the total free energy of a protein in the aqueous solution at constant pH, and to calculate the pH-dependent properties. Method MD-pH-ET possesses the unique features: 1) it uses the most precise and computational-effective realization of calculation of the electrostatic energy of a protein in water solution, the model of continuous dielectric media with Poisson equation and the generalized Born method with "ideal" Born atomic radii; 2) it uses the same model of the potential energy surface in the ionization-conformational phase space, both for calculating the potential energy of the protein and atomic forces and for determining the most probable ionization states; 3) it calculates the total free energy of the protein in the aqueous solution in proton reservoir under the conditions of equilibrium titration. The workability of the new method MD-pH-ET is demonstrated for the molecule of protein BPTI. PMID:21634122

Vorob'ev, Iu N



Household Salt Iodine Content Estimation with the Use of Rapid Test Kits and Iodometric Titration Methods  

PubMed Central

Background: Universal salt iodization remains the best strategy for controlling iodine deficiency disorders in Nepal. Aims: This study was designed to study the salt types and the household salt iodine content of school aged children in the hilly and the plain districts of eastern Nepal. Material and Methods: This cross-sectional study was carried out on school children of seven randomly chosen schools from four districts, namely, Sunsari, Dhankuta, Sankhuwasabha and Tehrathum of eastern Nepal. The school children were requested to bring two teaspoonfuls (approx. 12-15 g) of the salt which was consumed in their households, in a tightly sealed plastic pouch. The salt types were categorized, and the salt iodine content was estimated by using rapid test kits and iodometric titrations. The association of the salt iodine content of the different districts were tested by using the Chi-square test. The sensitivity, specificity, positive predictive values, and negative predictive values of the rapid test kits were compared with the iodometric titrations. Results: Our study showed that mean±SD values of the salt iodine content in the four districts, namely, Sunsari, Dhankuta, Sankhuwasabha and Tehrathum were 34.2±17.9, 33.2±14.5, 27.4±15.1 and 48.4±15.6 parts per million (ppm). There were 270 (38.2%) households which consumed crystal salt and 437(61.8%) of the households consumed packet salts. Conclusions: Our study recommends a regular monitoring of the salt iodization programs in these regions. More families should be made aware of the need to ensure that each individual consumes iodized salt. PMID:23814736

Nepal, Ashwini Kumar; Raj Shakya, Prem; Gelal, Basanta; Lamsal, Madhab; Brodie, David A; Baral, Nirmal



Titration of transport and modifier sites in the red cell anion transport system  

PubMed Central

This work demonstrates the existence of titratable transport and modifier sites in the anion transport system of human red cells. Effects of alkaline extracellular pH on chloride exchange were studied up to pH 13 at 0 degrees C. The studies revealed two sets of reversible titratable groups. One set, having a pK of or approximately 11, appeared to be identical with the inhibitory halide-binding modifier site. Deprotonation of this site stimulated anion transport. The apparent dissociation constants of chloride and iodide at this modifier site were 0.3 and 0.06 M, respectively, and it was confirmed that the organic sulfonate NAP-taurine inhibits anion transport reversibly by a high-affinity interaction with halide-binding modifier sites at the extracellular side of the membrane. Other groups, with apparent pK of or approximately 12 at chloride concentrations above 0.1 M, were named as "transport sites" because transport function depended totally on their protonation. The apparent pK decreased when extracellular halide concentrations was lowered below 0.1 M. It was dependent of the intracellular chloride concentration, and was equally sensitive to extracellular pH of 13, was fully reversible. Hydroxyl ions were not transported to an appreciable extent by the anion exchange system. The pK values of both sets of groups make it likely that they are both arginyl residues, functioning as anion recognition sites similar to the role of functionally essential arginyl residues observed with numerous enzymes. PMID:6276496



Spectroscopic Needs for Calibration of LSST Photometric Redshifts  

E-print Network

This white paper summarizes the conclusions of the Snowmass White Paper "Spectroscopic Needs for Imaging Dark Energy Experiments" (arXiv:1309.5384) which are relevant to the calibration of LSST photometric redshifts; i.e., the accurate characterization of biases and uncertainties in photo-z's. Any significant miscalibration will lead to systematic errors in photo-z's, impacting nearly all extragalactic science with LSST. As existing deep redshift samples have failed to yield highly-secure redshifts for a systematic 20%-60% of their targets, it is a strong possibility that future deep spectroscopic samples will not solve the calibration problem on their own. The best options in this scenario are provided by cross-correlation methods that utilize clustering with objects from spectroscopic surveys (which need not be fully representative) to trace the redshift distribution of the full sample. For spectroscopy, the eBOSS survey would enable a basic calibration of LSST photometric redshifts, while the expected LSST...

Schmidt, Samuel J; Abate, Alexandra




SciTech Connect

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.

Sanders, N. E.; Soderberg, A. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Levesque, E. M., E-mail: [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States)



Photometric study of the IC 65 group of galaxies  

E-print Network

We carry out a photometric study of a poor group of late-type galaxies around IC 65, with the aim: (a) to search for new dwarf members and to measure their photometric characteristics; (b) to search for possible effects of mutual interactions on the morphology and star-formation characteristics of luminous and faint group members; (c) to evaluate the evolutionary status of this particular group. We make use of our BRI CCD observations, DPOSS blue and red frames, and the 2MASS JHK frames. In addition, we use the HI imaging data, the far-infrared and radio data from the literature. Search for dwarf galaxies is made using the SExtractor software. Detailed surface photometry is performed with the MIDAS package. Four LSB galaxies were classified as probable dwarf members of the group and the BRI physical and model parameters were derived for the first time for all true and probable group members. Newly found dIrr galaxies around the IC 65 contain a number of H II regions, which show a range of ages and propagating star-formation. Mildly disturbed gaseous and/or stellar morphology is found in several group members. Various structural, dynamical, and star-forming characteristics let us conclude that the IC 65 group is a typical poor assembly of late-type galaxies at an early stage of its dynamical evolution with some evidence of intragroup (tidal) interactions.

J. Vennik; U. Hopp



WFC3: Improvements to WFC3 UVIS Photometric Calibration  

NASA Astrophysics Data System (ADS)

The Wide Field Camera 3 (WFC3) is a fourth-generation imaging instrument installed on the Hubble Space Telescope (HST) in May 2009. It contains both an IR and a UVIS channel. The latter, which covers the 200-1000nm spectral range, consists of two 2K x 4K CCD chips along with 62 spectral elements and one grism. The two CCD chips were manufactured on different wafers. As a result, there are differences in the two chips’ properties and behaviors, such as their lithography imprint patterns, their sensitivity responses, and their measured quantum efficiency (QE), particularly in the UV. Therefore, the WFC3 team developed a chip-dependent approach to the photometric calibration, where each chip now has its own separate calibration. We discuss the impacts of this new approach and its implementation in the calibration pipeline, presenting the new zero points and header keywords, as well as the new flat fields. We also present the latest trends in the contamination monitoring, which obtains regular imaging and grism spectroscopy of the white dwarf, GRW+70, in key filters F218W, F225W, F336W, F814W, and F606W.No contamination effects have been detected, though there is evidence for a small photometric drift (<1% over 3 years). We anticipate that these efforts will improve UV imaging with WFC3.

Gosmeyer, Catherine; Baggett, Sylvia M.; Bowers, Ariel; Dahlen, Tomas; Deustua, Susana E.; Hammer, Derek; Mack, Jennifer



Photometric Analysis of the Overcontact Binary CW Cas  

NASA Astrophysics Data System (ADS)

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.

Wang, J. J.; Qian, S. B.; He, J. J.; Li, L. J.; Zhao, E. G.



An automated algorithm for determining photometric redshifts of quasars  

NASA Astrophysics Data System (ADS)

We employ k-nearest neighbor algorithm (KNN) for photometric redshift measurement of quasars with the Fifth Data Release (DR5) of the Sloan Digital Sky Survey (SDSS). KNN is an instance learning algorithm where the result of new instance query is predicted based on the closest training samples. The regressor do not use any model to fit and only based on memory. Given a query quasar, we find the known quasars or (training points) closest to the query point, whose redshift value is simply assigned to be the average of the values of its k nearest neighbors. Three kinds of different colors (PSF, Model or Fiber) and spectral redshifts are used as input parameters, separatively. The combination of the three kinds of colors is also taken as input. The experimental results indicate that the best input pattern is PSF + Model + Fiber colors in all experiments. With this pattern, 59.24%, 77.34% and 84.68% of photometric redshifts are obtained within ?z < 0.1, 0.2 and 0.3, respectively. If only using one kind of colors as input, the model colors achieve the best performance. However, when using two kinds of colors, the best result is achieved by PSF + Fiber colors. In addition, nearest neighbor method (k = 1) shows its superiority compared to KNN (k ? 1) for the given sample.

Wang, Dan; Zhang, Yanxia; Zhao, Yongheng



Mapping extinction using GALEX and SDSS photometric observations  

NASA Astrophysics Data System (ADS)

The primary objective of this work is to create an all sky extinction map of the Milky Way galaxy. We have cross-matched the Sloan Digital Sky Survey (SDSS data release 8) photometric observations with that of Galaxy Evolution Explorer (GALEX data release 6). This provides a wide range of wavelength coverage from Far Ultra-Violet through the optical spectrum and gives one unique SDSS source for every GALEX source. We discuss a sample of ˜32000 objects in the north galactic pole (?75° latitude) from this combined database. The Castelli and Kurucz Atlas was fit to the photometric observations of each star, best fit being determined using a chi-square test. Best fit parameters provide the spectral type and extinction towards each of the objects. The shift in magnitude obtained during the best-fit can be used to determine the distance to each of the stars. With this data, a comprehensive extinction map can be made for the high-latitude objects and later extended to all-sky.

Krishnamoorthy, Preethi; Gudennavar, S. B.; Murthy, Jayant




SciTech Connect

We determine photometric metal abundance estimates for individual main-sequence stars in the Virgo Overdensity (VOD), which covers almost 1000 deg{sup 2} on the sky, based on a calibration of the metallicity sensitivity of stellar isochrones in the gri filter passbands using field stars with well-determined spectroscopic metal abundances. Despite the low precision of the method for individual stars, we derive [Fe/H] = -2.0 +- 0.1(internal) +- 0.5(systematic) for the metal abundance of the VOD from photometric measurements of 0.7 million stars in the northern Galactic hemisphere with heliocentric distances from approx10 kpc to approx20 kpc. The metallicity of the VOD is indistinguishable, within DELTA[Fe/H] <= 0.2, from that of field halo stars covering the same distance range. This initial application suggests that the Sloan Digital Sky Survey gri passbands can be used to probe the properties of main-sequence stars beyond approx10 kpc, complementing studies of nearby stars from more metallicity-sensitive color indices that involve the u passband.

An, Deokkeun [Infrared Processing and Analysis Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125 (United States); Johnson, Jennifer A.; Pinsonneault, Marc H.; Terndrup, Donald M.; Masseron, Thomas [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Beers, Timothy C.; Lee, Young Sun [Department of Physics and Astronomy and JINA (Joint Institute for Nuclear Astrophysics), Michigan State University, E. Lansing, MI 48824 (United States); Delahaye, Franck [Service d'Astrophysique, CEA/DSM/IRFU/SAp, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Yanny, Brian, E-mail: deokkeun@ipac.caltech.ed [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States)



Quantifying photometric observing conditions on Paranal using an IR camera  

NASA Astrophysics Data System (ADS)

A Low Humidity and Temperature Profiling (LHATPRO) microwave radiometer, manufactured by Radiometer Physics GmbH (RPG), is used to monitor sky conditions over ESO's Paranal observatory in support of VLT science operations. In addition to measuring precipitable water vapour (PWV) the instrument also contains an IR camera measuring sky brightness temperature at 10.5 ?m. Due to its extended operating range down to -100 °C it is capable of detecting very cold and very thin, even sub-visual, cirrus clouds. We present a set of instrument flux calibration values as compared with a detrended fluctuation analysis (DFA) of the IR camera zenith-looking sky brightness data measured above Paranal taken over the past two years. We show that it is possible to quantify photometric observing conditions and that the method is highly sensitive to the presence of even very thin clouds but robust against variations of sky brightness caused by effects other than clouds such as variations of precipitable water vapour. Hence it can be used to determine photometric conditions for science operations. About 60 % of nights are free of clouds on Paranal. More work will be required to classify the clouds using this technique. For the future this approach might become part of VLT science operations for evaluating nightly sky conditions.

Kerber, Florian; Querel, Richard R.; Hanuschik, Reinhard



Photometric Redshift and Classification for the XMM-COSMOS Sources  

NASA Astrophysics Data System (ADS)

We present photometric redshifts and spectral energy distribution (SED) classifications for a sample of 1542 optically identified sources detected with XMM in the COSMOS field. Our template fitting classifies 46 sources as stars and 464 as nonactive galaxies, while the remaining 1032 require templates with an active galactic nucleus (AGN) contribution. High accuracy in the derived photometric redshifts was accomplished as the result of (1) photometry in up to 30 bands with high-significance detections, (2) a new set of SED templates, including 18 hybrids covering the far-UV to mid-infrared, which have been constructed by the combination of AGNs and nonactive galaxies templates, and (3) multiepoch observations that have been used to correct for variability (most important for type 1 AGNs). The reliability of the photometric redshifts is evaluated using the subsample of 442 sources with measured spectroscopic redshifts. We achieved an accuracy of ? _{? z/(1+z_spec)} = 0.014 for i* AB < 22.5 (? _{? z/(1+z_spec)} ˜ 0.015 for i* AB < 24.5). The high accuracies were accomplished for both type 2 (where the SED is often dominated by the host galaxy) and type 1 AGNs and QSOs out to z = 4.5. The number of outliers is a large improvement over previous photometric redshift estimates for X-ray-selected sources (4.0% and 4.8% outliers for i* AB < 22.5 and i* AB < 24.5, respectively). We show that the intermediate band photometry is vital to achieving accurate photometric redshifts for AGNs, whereas the broad SED coverage provided by mid-infrared (Spitzer/IRAC) bands is important to reduce the number of outliers for normal galaxies. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under NASA contract NAS 5-26555. Also based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Also based on data collected at: the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA; the European Southern Observatory under Large Program 175.A-0839, Chile; Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory and the National Optical Astronomy Observatory, which are operated by AURA under cooperative agreement with the National Science Foundation; and the Canada-France-Hawaii Telescope with MegaPrime/MegaCam operated as a joint project by the CFHT Corporation, CEA/DAPNIA, the NRC and CADC of Canada, the CNRS of France, TERAPIX and the University of Hawaii.

Salvato, M.; Hasinger, G.; Ilbert, O.; Zamorani, G.; Brusa, M.; Scoville, N. Z.; Rau, A.; Capak, P.; Arnouts, S.; Aussel, H.; Bolzonella, M.; Buongiorno, A.; Cappelluti, N.; Caputi, K.; Civano, F.; Cook, R.; Elvis, M.; Gilli, R.; Jahnke, K.; Kartaltepe, J. S.; Impey, C. D.; Lamareille, F.; Le Floc'h, E.; Lilly, S.; Mainieri, V.; McCarthy, P.; McCracken, H.; Mignoli, M.; Mobasher, B.; Murayama, T.; Sasaki, S.; Sanders, D. B.; Schiminovich, D.; Shioya, Y.; Shopbell, P.; Silverman, J.; Smol?i?, V.; Surace, J.; Taniguchi, Y.; Thompson, D.; Trump, J. R.; Urry, M.; Zamojski, M.



Cadmium binding to a histidine-rich glycoprotein from marine mussel blood plasma: potentiometric titration and equilibrium speciation modeling.  


Cadmium-binding parameters (conditional stability constants and carrying capacities) of Mytilus edulis blood plasma histidine-rich glycoprotein (HRG) were investigated by potentiometric titrations using a Cd ion-specific electrode. Titration data were applied to a single-component complexation model and expressed as Scatchard plots that were analyzed using the graphical curve peeling method and the algebraic statistical mechanical method. These sets of binding parameters, derived for the purified HRG, were subsequently entered into the geochemical speciation model MINTEQA2 and then used to simulate the experimental titration, thereby determining which set of log K and CL values best represented the titration data. The Cd binding to HRG was best described by a two-class model with log K values of 7.65 +/- 0.10 and 5.41 +/- 0.06 M-1 and carrying capacities of 6.0 +/- 1.2 and 9.5 +/- 0.4 sites/molecule, respectively. At concentration of total Cd measured in the blood plasma of field-collected mussels (< or = 2 x 10(-7) M), plasma Cd speciation would be dominated by the strong affinity sites of HRG (> 93.5% of total Cd binds to HRG), whereas HRG itself would only be 0.05% saturated with Cd, indicating a high-capacity, apparently nonsaturable Cd transport system. PMID:11434304

Nair, P S; Robinson, W E



Electrically generated lead(IV) acetate and manganese(III) acetate as reagents for coulometric redox titrations in acetic acid  

Microsoft Academic Search

Summary The conditions were investigated for electrochemical generation of lead(IV) acetate in acetic acid by oxidation of lead(II) acetate on a lead dioxide electrode and on a platinum electrode. Bivalent manganese ions are quantitatively oxidized on a platinum electrode to the tervalent state in the same solvent. Coulometric titration methods for the determination of small amounts of hydroquinone in acetic

Tibor J. Pastor; Vilim J. Vajgand; Zorica Kicovic



Determination of chemical oxygen demand (COD) using ultrasound digestion and oxidation-reduction potential-based titration  

Microsoft Academic Search

A new method for determining wastewater chemical oxygen demand (COD) using ultrasonic digestion and titration based on oxidation reduction potential (ORP) was developed. COD values of potassium hydrogen phthalate solution obtained by ultrasonic digestion were well matched with those obtained using Standard Methods. When applied to determine COD of real wastewater collected from a local treatment plant, results from the

Hyunook Kim; Honglae Lim; Mark F. Colosimo



A Comparative Study of Spectrophotometric and Iodometric Back Titration Methods for Hydrogen Sulfide Determination in Anoxic Basins  

Microsoft Academic Search

Iodometric Back Titration (IBT) and Spectrophotometric (SPM) methods are two common methods used in the determination of hydrogen sulfide concentrations in anoxic basins, like in the upper sections of the Black Sea anoxic waters. Although the results obtained by both methods are in agreement when the concentrations of sulfide are higher than 30 ?M\\/1, IBT analysis gives more reproducible results

Özden Batürk; Alexander Romanov; Serap Gokmen; Sergey Konovalov



Complexometric titration of Ti(IV) with 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol as indicator.  


A method for determination of titanium by a reverse titration with EDTA in the presence of hydrogen peroxide, with 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol as indicator, is presented; use of the method for analysis of titanium paints is also described. PMID:18965076

Marini, H J; Anton, R I; Olsina, R A




EPA Science Inventory

The iodimetric titration method for the determination of bromide involves the observation of various color changes, making the method unsuitable for use with samples that are highly colored. A modification is described, which extends the usefulness of the method to highly colored...


Simultaneous measurement of gastric acid and duodenal alkali secretion by in situ titration in health and disease  

Microsoft Academic Search

We have devised a technique for simultaneously measuring the acid secretion into the stomach and alkali into the duodenum by in situ titration using a modification of the technique of Fordtran and Walsh. Using this technique, the results of acid and alkali secretion measured simultaneously were identical with those obtained using the conventional aspiration method on separate days. In response

P Dubey; S Nundy



Determination of ion exchange equilibrium constants of strongly acidic resins with alkaline-earth metals by means of the potentiometric titrations technique  

Microsoft Academic Search

A recently developed methodology for the determination of ion exchange equilibrium constants has been applied to ion exchange systems of 1:2 stoichiometry. Potentiometric titrations with variable ionic strength were carried out. Ionic medium titrations were performed for the estimation of the liquid junction potential. The modified Bromley's methodology and the Wilson model were used for the estimation of the activity

Gregorio Borge; Gorka Arana; Luis A. Fernández; Juan M. Madariaga



Retrieving photometric properties of desert surfaces in China using the Hapke model and MISR data  

Microsoft Academic Search

The retrieval of photometric properties of desert surfaces is an important first step in the parameterization of land surface components of regional dust emission and global radiation models and in Earth system modeling. In this study, the values of Hapke's photometric parameters (?, h, b, c, B0, and ??) were retrieved from the Multi-angle Imaging SpectroRadiometer (MISR) instrument at locations

Yunzhao Wu; Peng Gong; Qiang Liu; Adrian Chappell



Indirect Photometric and Fluorometric Detection in High-Performance Liquid Chromatography: A Tutorial Review  

Microsoft Academic Search

A review of indirect photometric and fluorometric detection in high-performance liquid chromatography (HPLC) is presented. A functional definition of indirect detection, somewhat broader and simpler than what was often used to characterize these techniques, was employed for this review. Emphasis was placed on distinguishing different approaches to indirect photometric and fluorometric detection in HPLC based on the interactions which occur

Xiaoxuan Shen; Sterling A. Tomellini



Spectroscopic Needs for Training of LSST Photometric Redshifts  

E-print Network

This white paper summarizes those conclusions of the Snowmass White Paper "Spectroscopic Needs for Imaging Dark Energy Experiments" (arXiv:1309.5384) which are relevant to the training of LSST photometric redshifts; i.e., the use of spectroscopic redshifts to improve algorithms and reduce photo-z errors. The larger and more complete the available training set is, the smaller the RMS error in photo-z estimates should be, increasing LSST's constraining power. Among the better US-based options for this work are the proposed MANIFEST fiber feed for the Giant Magellan Telescope or (with lower survey speed) the WFOS spectrograph on the Thirty Meter Telescope (TMT). Due to its larger field of view and higher multiplexing, the PFS spectrograph on Subaru would be able to obtain a baseline training sample faster than TMT; comparable performance could be achieved with a highly-multiplexed spectrograph on Gemini with at least a 20 arcmin diameter field of view.

Abate, Alexandra; Schmidt, Samuel J



Periodic photometric variability of the brown dwarf Kelu-1  

E-print Network

We have detected a strong periodicity of 1.80+/-0.05 hours in photometric observations of the brown dwarf Kelu-1. The peak-to-peak amplitude of the variation is ~1.1% (11.9+/-0.8 mmag) in a 41nm wide filter centred on 857nm and including the dust/temperature sensitive TiO & CrH bands. We have identified two plausible causes of variability: surface features rotating into- and out-of-view and so modulating the light curve at the rotation period; or, elliposidal variability caused by an orbiting companion. In the first scenario, we combine the observed vsin(i) of Kelu-1 and standard model radius to determine that the axis of rotation is inclined at 65+/-12 degrees to the line of sight.

F. J. Clarke; C. G. Tinney; K. R. Covey



Photometric and polarimetric study of two BL LAC objects  

SciTech Connect

The results are given of polarimetric and photometric observations of the BL Lac objects OI 090.4 over the period 1979-1982 and B2 1418 + 54 over the period 1980-1982. For both objects it was noted that there was variability on a time scale of from several years to several days. The comparison of the polarimetric parameters indicates the existence of a preferred direction of polarization both for B2 1418 + 54 (theta /sub O/ = 120/sup 0/), and for OI 090.4 (theta /sub O/ = 50/sup 0/), which points to a stable magnetic field. For OI 090.4 it was observed that there was a certain dependence of the polarization parameters on the wavelength.

Marchenko, S.G.



A Photometric Method for Quantifying Asymmetries in Disk Galaxies  

E-print Network

A photometric method for quantifying deviations from axisymmetry in optical images of disk galaxies is applied to a sample of 32 face-on and nearly face-on spirals. The method involves comparing the relative fluxes contained within trapezoidal sectors arranged symmetrically about the galaxy center of light, excluding the bulge and/or barred regions. Such a method has several advantages over others, especially when quantifying asymmetry in flocculent galaxies. Specifically, the averaging of large regions improves the signal-to-noise in the measurements; the method is not strongly affected by the presence of spiral arms; and it identifies the kinds of asymmetry that are likely to be dynamically important. Application of this "method of sectors" to R-band images of 32 disk galaxies indicates that about 30% of spirals show deviations from axisymmetry at the 5-sigma level.

David A. Kornreich; Martha P. Haynes; Richard V. E. Lovelace



Fitting isochrones to open cluster photometric data. III. Estimating metallicities from UBV photometry  

NASA Astrophysics Data System (ADS)

The metallicity is a critical parameter that affects the correct determination of fundamental characteristics of a stellar cluster and has important implications in Galactic and stellar evolution research. Fewer than 10% of the 2174 currently cataloged open clusters have their metallicity determined in the literature. In this work we present a method for estimating the metallicity of open clusters via non-subjective isochrone fitting using the cross-entropy global optimization algorithm applied to UBV photometric data. The free parameters distance, reddening, age, and metallicity simultaneously determined by the fitting method. The fitting procedure uses weights for the observational data based on the estimation of membership likelihood for each star, which considers the observational magnitude limit, the density profile of stars as a function of radius from the center of the cluster, and the density of stars in multi-dimensional magnitude space. We present results of [Fe/H] for nine well-studied open clusters based on 15 distinct UBV data sets. The [Fe/H] values obtained in the ten cases for which spectroscopic determinations were available in the literature agree, indicating that our method provides a good alternative to determining [Fe/H] by using an objective isochrone fitting. Our results show that the typical precision is about 0.1 dex. Appendix is available in electronic form at

Oliveira, A. F.; Monteiro, H.; Dias, W. S.; Caetano, T. C.




NASA Astrophysics Data System (ADS)

PhAst (Photometry and Astrometry) is an IDL program designed to measure the photometry and astrometry of near Earth objects (NEOs) from CCD observations by ground-based telescopes. The goal of PhAst is to simplify the observation of NEOs and the reporting of their characteristics to the International Astronomical Union’s Minor Planetary Center with a focus on NEO astrometry. We compared the photometric results of PhAst against results derived using the photometry procedures in the Image Reduction and Analysis Facility (IRAF). We used CCD observations of Landolt standard stars that were obtained with the 2.1-m telescope at the Kitt Peak National Observatory. We found the photometry from PhAst to be on average nearly identical to the photometry derived using IRAF. PhAst can be considered reliable when measuring the magnitude of a NEO. Kutsop 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).

Kutsop, Nicholas; Mighell, K. J.; Allen, L.; Trueblood, M.; Crawford, R.



Strömgren photometric survey in the Galactic anticenter direction  

NASA Astrophysics Data System (ADS)

Aims: The main purpose is to map the radial variation of the stellar space density for the young stellar population in the Galactic anticenter direction in order to understand the structure and location of the Perseus spiral arm. Methods: A uvbyH? Strömgren photometric survey covering 16 deg2 in the anticenter direction was carried out using the Wide Field Camera at the Isaac Newton Telescope. This is the natural photometric system for identifying young stars and obtaining accurate estimates of individual distances and ages. The calibration to the standard system was undertaken using open clusters. Results: We present a main catalog of 35 974 stars with all Strömgren indexes and a more extended one with 96 980 stars with partial data. The central 8 deg2 have a limiting magnitude of V ~ 17m, while the outer region reaches V ~ 15.m5. These large samples will permit us to analyze the stellar surface density variation associated to the Perseus arm also to study the properties of the stellar component and the interstellar extinction in the anticenter direction. Final catalog and catalog with individual measurements are only available in electronic form at the CDS via anonymous ftp to ( or via on observations made with the Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

Monguió, M.; Figueras, F.; Grosbøl, P.



New Asteroid Shape Models Derived from the Lowell Photometric Database  

NASA Astrophysics Data System (ADS)

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 ( - 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.

Durech, Josef; Hanus, J.; Vanco, R.; Oszkiewicz, D.; Bowell, E.



Photometric Type Ia supernova surveys in narrow-band filters  

NASA Astrophysics Data System (ADS)

We study the characteristics of a narrow-band Type Ia supernova (SN) survey through simulations based on the upcoming Javalambre Physics of the accelerating Universe Astrophysical Survey. This unique survey has the capabilities of obtaining distances, redshifts and the SN type from a single experiment thereby circumventing the challenges faced by the resource-intensive spectroscopic follow-up observations. We analyse the flux measurements signal-to-noise ratio and bias, the SN typing performance, the ability to recover light-curve parameters given by the SALT2 model, the photometric redshift precision from Type Ia SN light curves and the effects of systematic errors on the data. We show that such a survey is not only feasible but may yield large Type Ia SN samples (up to 250 SNe at z < 0.5 per month of search) with low core-collapse contamination (˜1.5 per cent), good precision on the SALT2 parameters (average ? _{m_B}=0.063, ? _{x_1}=0.47 and ?c = 0.040) and on the distance modulus (average ?? = 0.16, assuming an intrinsic scatter ?int = 0.14), with identified systematic uncertainties ?sys ? 0.10?stat. Moreover, the filters are narrow enough to detect most spectral features and obtain excellent photometric redshift precision of ?z = 0.005, apart from ˜2 per cent of outliers. We also present a few strategies for optimizing the survey's outcome. Together with the detailed host galaxy information, narrow-band surveys can be very valuable for the study of SN rates, spectral feature relations, intrinsic colour variations and correlations between SN and host galaxy properties, all of which are important information for SN cosmological applications.

Xavier, Henrique S.; Abramo, L. Raul; Sako, Masao; Benítez, Narciso; Calvão, Maurício O.; Ederoclite, Alessandro; Marín-Franch, Antonio; Molino, Alberto; Reis, Ribamar R. R.; Siffert, Beatriz B.; Sodré, Laerte.



Miniature photometric stereo system for textile surface structure reconstruction  

NASA Astrophysics Data System (ADS)

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.

Gorpas, Dimitris; Kampouris, Christos; Malassiotis, Sotiris



Carbon Stars In Andromeda. II. Demographics and Photometric Properties  

NASA Astrophysics Data System (ADS)

This is the second of two talks about a sample of newly-discovered carbon stars in the Andromeda galaxy (M31). As explained in the first talk, these stars were identified on the basis of their spectroscopic characteristics using Keck/DEIMOS spectra obtained as part of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) survey. We explore the physical properties of strong and weak carbon stars using photometric data from a Hubble Space Telescope Multi-Cycle Treasury program: Panchromatic Hubble Andromeda Treasury (PHAT). The PHAT data set includes deep photometry in six filters: two in the ultraviolet, two in the optical, and two in the near infrared. The carbon stars appear to be in the asymptotic giant branch stage of their evolution as evidenced by the fact that they lie above the tip of the red giant branch and are cleanly separated from normal (i.e., oxygen-rich) giants in color-magnitude diagrams. We study the spatial distribution of carbon stars in M31 and use kinematics to determine whether they belong to M31's thin disk, thick disk, or spheroid. These carbon stars serve as highly visible tracers of the intermediate-mass, intermediate-age stellar population in M31; they are important markers in the study of the star-formation history of the galaxy. This research was part of the SPLASH and PHAT collaboration. We are grateful to the National Science Foundation and NASA for funding support. AN's participation was under the auspices of UCSC's Science Internship Program.

Guhathakurta, Puragra; Hamren, K.; Dorman, C.; Toloba, E.; Seth, A.; Dalcanton, J.; Nayak, A.; PHAT Collaboration; SPLASH Collaboration



The photometric detection of known sun occluding orbital debris  

NASA Astrophysics Data System (ADS)

In this research, discrete, digital, Sun transit images are used for the photometric detection of the shadows of Sun occluding satellites. A theoretical pixel occlusion ratio is developed for use in the detection and the occluding area determination of satellites and orbital debris, traveling over known, or predicted, spatial temporal paths during transit. To verify the occluding area determination of a large satellite, a recorded transit of the International Space Station is analyzed. Also an experimental system, funded by a Beverly Sears Grant and a Sigma-Xi Grant-In-Aid of Research, consisting of a Meade ETX-90 telescope, and a Lumenera LU-075 camera is constructed to detect satellites and orbital debris in solar transits. The photometrically measured total occluding area of the Terra EOS-AM1 satellite, recorded in two separate transits, is shown to be consistent with the predicted occluding area of the satellite shadow. Further investigated is the theoretical resolution limit of this detection, as the occluding shadow becomes much smaller than a pixel area. The central limit theorem is used to approximate the maximum detection statistic, which can be achieved when integrating a matched spatial temporal path, containing the moving shadow. This detection statistic is predicted to be a function of the pixel occlusion ratio, the design parameters of the spatial temporal path, and the approximated Poisson variance of the photon count in each pixel. When the measured detection statistics of the two recorded transits are compared with the prediction model, the measurements agree with half the predicted value. This experimental error is largely attributed to filter mismatch in the spatial temporal path, and a spatial temporal variance in the recorded Sun transit images, which is larger than predicted by theory. These experimental verifications of the proposed theory are used to extrapolate the general limitations and capabilities of a system designed to detect Sun occluding orbital debris. In particular, the potential resolution capability of a system designed to detect smaller orbital debris is theorized.

Poller, Brian J.



Measurement of atmospheric OH by titration of near-IR fluorescent dyes  

NASA Technical Reports Server (NTRS)

Recent research has shown that certain polymethine dyes can be detected at ultratrace levels (greater than or equal to 6x10(exp -14) M) in solution by fluorimetry. These detection limits are possible because of the inherent sensitivity of fluorescence techniques, because the dyes fluoresce in the near infrared region where background interference is negligible, and because powerful infrared diode lasers are now available to improve the signal to noise ratio. Other work has shown that the hydroxyl radical destroys the ability of polymethine dyes to fluoresce. These observations form the basis for a new hydroxyl radical detector that is essentially a fluorometric titrator. Theoretically, the detector should show an acceptable sensitivity and response time. Assuming that the atmospheric HO concentration is about 10(exp -11) moles m(exp -3) (i.e. 10(exp 6) molecules cm(exp -3)), then 10 L of air 'titrated' with 20 mL of 10(exp -11) M dye solution (an easily detected concentration) should result in a drop in the fluorescent signal of 50 percent - a readily detectable change. At a flow rate of 3 L min(exp -1) the sampling time would be 3 minutes. The biggest potential problem is selectivity: other oxidants may also cause the fluorescence signal to be lost. The chemistry of polymethine dyes has not been studied in detail and so no quantitative data are available. However, a survey of the literature suggests that in general HO should react up to six orders of magnitude faster than HO2 and other radicals such as RO2 and RO. It should also react much more rapidly than H2O2 and O3. Thus it may be possible to discriminate kinetically against potential interfering substances. It was shown in the laboratory that 10(exp -4) M H2O2 has little effect on the absorption spectrum of the dye IR125 over a period of hours but that the band at 780 nm is slowly lost in water over a period of days even under argon in the dark. By contrast, DMSO solutions of IR125 are stable.

Betterton, Eric A.; Gast, Karl



Gusev Photometric Variability as Seen from the Orbit by HRSC\\/Mars-Express: Contribution of the Opposition Effect  

Microsoft Academic Search

The multi-angular HRSC dataset generated with the nadir-looking, stereo and photometric channels, is used to derive the surface photometric characteristics for mapping the variation of the soil\\/bedrock physical properties within Gusev crater.

P. C. Pinet; A. Jehl; Y. D. Daydou; S. Chevrel; D. Baratoux; F. Heuripeau; N. Manaud; A. Cord; H. Hoffmann; K. Gwinner; F. Scholten; T. Roatsch; G. Neukum



Peritonectomy procedures.  

PubMed Central

OBJECTIVE: New surgical procedures designed to assist in the treatment of peritoneal surface malignancy were sought. BACKGROUND: Decisions regarding the treatment of cancer depend on the anatomic location of the malignancy and the biologic aggressiveness of the disease. Some patients may have isolated intra-abdominal seeding of malignancy of limited extent or of low biologic grade. In the past, these clinical situations have been regarded as lethal. METHODS: The cytoreductive approach may require six peritonectomy procedures to resect or strip cancer from all intra-abdominal surfaces. RESULTS: These are greater omentectomy-splenectomy; left upper quadrant peritonectomy; right upper quadrant peritonectomy; lesser omentectomy-cholecystectomy with stripping of the omental bursa; pelvic peritonectomy with sleeve resection of the sigmoid colon; and antrectomy. CONCLUSIONS: Peritonectomy procedures and preparation of the abdomen for early postoperative intraperitoneal chemotherapy were described. The author has used the cytoreductive approach to achieve long-term, disease-free survival in selected patients with peritoneal carcinomatosis, peritoneal sarcomatosis or mesothelioma. Images Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. PMID:7826158

Sugarbaker, P H




SciTech Connect

We analyze photometric data in the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) to infer statistical properties of faint satellites associated with isolated bright galaxies (M{sub r} < -20.5) in the redshift range 0.03 < z < 0.1. The mean projected radial number density profile shows an excess of companions in the photometric sample around the primaries, with approximately a power-law shape that extends up to {approx_equal} 700 kpc. Given this overdensity signal, a suitable background subtraction method is used to study the statistical properties of the population of bound satellites, down to magnitude M{sub r} = -14.5, in the projected radial distance range 100 < r{sub p} /kpc < 3(R{sub vir}). The maximum projected distance corresponds to the range 470-660 kpc for the different samples. We have also considered a color cut consistent with the observed colors of spectroscopic satellites in nearby galaxies so that distant redshifted galaxies do not dominate the statistics. We have tested the implementation of this background subtraction procedure using a mock catalog derived from the Millennium simulation semianalytic galaxy catalog based on a {Lambda} cold dark matter model. We find that the method is effective in reproducing the true projected radial satellite number density profile and luminosity distributions, providing confidence in the results derived from SDSS data. We find that the spatial extent of satellite systems is larger for bright, red primaries. Also, we find a larger spatial distribution of blue satellites. For the different samples analyzed, we derive the average number of satellites and their luminosity distributions down to M{sub r} = -14.5. The mean number of satellites depends very strongly on host luminosity. Bright primaries (M{sub r} < -21.5) host on average {approx}6 satellites with M{sub r} < -14.5. This number is reduced for primaries with lower luminosities (-21.5 < M{sub r} < -20.5) which have less than one satellite per host. We provide Schechter function fits to the luminosity distributions of satellite galaxies where the resulting faint-end slopes equal to 1.3 {+-} 0.2, consistent with the universal value. This shows that satellites of bright primaries lack an excess population of faint objects, in agreement with the results in the Milky Way and nearby galaxies.

Lares, M.; Lambas, D. G.; Dominguez, M. J. [Instituto de Astronomia Teorica y Experimental (CONICET-UNC), Observatorio Astronomico de Cordoba (UNC), Laprida 854, X5000BGR, Cordoba (Argentina)



FIA titrations of ephedrine in pharmaceutical formulations with a PVC tetraphenylborate tubular electrode.  


A flow injection system for the titration of ephedrine in pharmaceutical products with potentiometric detection was developed. For this purpose a tetraphenylborate tubular electrode was constructed. The electrode was prepared without inner reference solution and with a PVC membrane based on tetrapentylammonium tetraphenylborate as ion exchanger and 2-nitrophenylphenyl ether as mediator solvent. Its operational characteristics were evaluated in a low dispersion manifold and compared with more conventionally shaped electrodes using the same sensor. In the pH range 2.5-11.5, the electrodes showed linear response between 3.8 x 10(-6) and 0.1 M with a slope of -56.4 mV/log[BPh4]. Ephedrine determinations in pharmaceutical products were carried out in a single channel manifold with a mixing chamber incorporated and using the tubular electrode as detector. Recovery rates of 98.6 +/- 2.5% were obtained in the analysis of tables, nasal drops and syrups with a sampling rate of about 60 h-1. PMID:9696556

Alçada, M N; Lima, J L; Montenegro, M C



Treatment of Graves' disease by carbimazole: high dose with thyroxine compared to titration dose.  


A comparative study of high-dose (HD, carbimazole 60 mg plus thyroxine 100-150 micrograms daily) and titration-dose (TD) regimens of carbimazole was carried out in 70 patients with Graves' disease, the patients being assigned randomly to one or other regimen. The treatment was given for 1 year and follow-up was for 2 years after stopping treatment. In both groups, recurrence of hyperthyroidism occurred, most commonly during the first 6 months (35% of HD and 44% of TD). By 2 years after stopping treatment, recurrence had occurred in 50% of the HD and 66% of the TD group. The differences were not significant. Thyroid antibodies, serum thyroglobulin and pertechnetate uptake fell similarly in both groups during treatment. Cigarette smoking was similar in both the groups and did not influence the frequency of relapse. In both HD and TD groups, when relapsing patients were examined according to whether they relapsed early (within 6 months or less) or late it was found that those who relapsed late were, in respect of goitre size, pertechnetate uptake and presence of detectable plasma TSH, similar to the patients who did not relapse at all. In conclusion, the changes in the measured variables and the progress of the patients was similar whether treated by the HD or TD regimen. PMID:8075780

Edmonds, C J; Tellez, M



Titration of high dose sedation is effective in severe tetanus: a case report  

PubMed Central

Introduction Tetanus is a fatal infectious disease. It could cause typical signs like pain, headache, stiffness, and spasms of facial muscles as well as trunk and skeletal muscles. The symptoms are risus sardonicus, trismus and opisthotonus. How to control the spasticity and rigidity of muscles is still a problem. Our object is to raise the feasibility of titration of high dose sedatives in the management of severe tetanus. Case presentation A 37-year-old woman was sustained a 2 cm wound in the right anterior part of chest. Then she developed progressive risus sardonicus, trismus and opisthotonus, elevated liver enzymes, creatine kinase, lactic acid and myoglobin. The patient was treated with continuous infusion of propofol (50-100 mg/h, 22 days) and midazolam (5-20 mg/h, 37 days) for sedation, vecuronium (1-6 mg/h, 25 days) for muscle relaxation. The symptoms of tetanus were controlled, and there were no side-effects appeared. Conclusion We report one case of severe tetanus. In this case, several types of sedative were administrated and most of them were high doses. The patient recovered while no complications remained. This case report indicated that combination and high dose of sedation for severe tetanus were feasible. We recommend this treatment as the guidance of similar patients. PMID:19918553

Chun, Pan; Ying-Zi, Huang; Yi, Yang



A visual detection of protein content based on titration of moving reaction boundary electrophoresis.  


A visual electrophoretic titration method was firstly developed from the concept of moving reaction boundary (MRB) for protein content analysis. In the developed method, when the voltage was applied, the hydroxide ions in the cathodic vessel moved towards the anode, and neutralized the carboxyl groups of protein immobilized via highly cross-linked polyacrylamide gel (PAG), generating a MRB between the alkali and the immobilized protein. The boundary moving velocity (V(MRB)) was as a function of protein content, and an acid-base indicator was used to denote the boundary displacement. As a proof of concept, standard model proteins and biological samples were chosen for the experiments to study the feasibility of the developed method. The experiments revealed that good linear calibration functions between V(MRB) and protein content (correlation coefficients R>0.98). The experiments further demonstrated the following merits of developed method: (1) weak influence of non-protein nitrogen additives (e.g., melamine) adulterated in protein samples, (2) good agreement with the classic Kjeldahl method (R=0.9945), (3) fast measuring speed in total protein analysis of large samples from the same source, and (4) low limit of detection (0.02-0.15 mg mL(-1) for protein content), good precision (R.S.D. of intra-day less than 1.7% and inter-day less than 2.7%), and high recoveries (105-107%). PMID:23567122

Wang, Hou-Yu; Guo, Cheng-Ye; Guo, Chen-Gang; Fan, Liu-Yin; Zhang, Lei; Cao, Cheng-Xi



A Universal Method for Fishing Target Proteins from Mixtures of Biomolecules using Isothermal Titration Calorimetry  

SciTech Connect

The most challenging tasks in biology include the identification of (1) the orphan receptor for a ligand, (2) the ligand for an orphan receptor protein, and (3) the target protein(s) for a given drug or a lead compound that are critical for the pharmacological or side effects. At present, several approaches are available, including cell- or animal-based assays, affinity labeling, solid-phase binding assays, surface plasmon resonance, and nuclear magnetic resonance. Most of these techniques are not easy to apply when the target protein is unknown and the compound is not amenable to labeling, chemical modification, or immobilization. Here we demonstrate a new universal method for fishing orphan target proteins from a complex mixture of biomolecules using isothermal titration calorimetry (ITC) as a tracking tool. We took snake venom, a crude mixture of several hundred proteins/peptides, as a model to demonstrate our proposed ITC method in tracking the isolation and purification of two distinct target proteins, a major component and a minor component. Identities of fished out target proteins were confirmed by amino acid sequencing and inhibition assays. This method has the potential to make a significant advancement in the area of identifying orphan target proteins and inhibitor screening in drug discovery and characterization.

Zhou, X.; Sun, Q; Kini, R; Sivaraman, J



Determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions by potentiometric titration  

SciTech Connect

A simple, fast method for the determination of uranium in uranium metal, uranium oxides, and uranyl nitrate solutions has been adapted from the Davies-Gray volumetric method to meet the needs of Y-12. One-gram duplicate aliquots of uranium metal or uranium oxide are dissolved in 1:1 HNO/sub 3/ and concentrated H/sub 2/SO/sub 4/ to sulfur trioxide fumes, and then diluted to 100-mL volume. Duplicate aliquots are then weighed for analysis. For uranyl nitrate samples, duplicate aliquots containing between 50 and 150 mg of U are weighed and analyzed directly. The weighed aliquot is transferred to a Berzelius beaker; 1.5 M sulfamic acid is added, followed in order by concentrated phosphoric acid, 1 M ferrous sulfate, and (after a 30-second interval) the oxidizing reagent. After a timed 3-minute waiting period, 100 mL of the 0.1% vanadyl sulfate-sulfuric acid mixture is added. The sample is then titrated past its endpoint with standard potassium dichromate, and the endpoint is determined by second derivative techniques on a mV/weight basis.

Tucker, H.L.; McElhaney, R.J.



Single-strand DNA translation initiation step analyzed by Isothermal Titration Calorimetry  

SciTech Connect

Is single-strand DNA translatable? Since the 60s, the question still remains whether or not DNA could be directly translated into protein. Some discrepancies in the results were reported about functional translation of single-strand DNA but all results converged on a similar behavior of RNA and ssDNA in the initiation step. Isothermal Titration Calorimetry method was used to determine thermodynamic constants of interaction between single-strand DNA and S30 extract of Escherichia coli. Our results showed that the binding was not affected by the nature of the template tested and the dissociation constants were in the same range when ssDNA (K{sub d} = 3.62 {+-} 2.1 x 10{sup -8} M) or the RNA corresponding sequence (K{sub d} = 2.7 {+-} 0.82 x 10{sup -8} M) bearing SD/ATG sequences were used. The binding specificity was confirmed by antibiotic interferences which block the initiation complex formation. These results suggest that the limiting step in translation of ssDNA is the elongation process.

Damian, Luminita, E-mail: [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France); IUB, School of Engineering and Science, D-28727 Bremen (Germany); Marty-Detraves, Claire, E-mail: [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France); Winterhalter, Mathias [IUB, School of Engineering and Science, D-28727 Bremen (Germany)] [IUB, School of Engineering and Science, D-28727 Bremen (Germany); Fournier, Didier, E-mail: [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France); Paquereau, Laurent, E-mail: [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France) [CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse (France); Universite de Toulouse, UPS, IPBS, F-31077 Toulouse (France)



Titration calorimetry of anesthetic-protein interaction: negative enthalpy of binding and anesthetic potency.  

PubMed Central

Anesthetic potency increases at lower temperatures. In contrast, the transfer enthalpy of volatile anesthetics from water to macromolecules is usually positive. The transfer decreases at lower temperature. It was proposed that a few selective proteins bind volatile anesthetics with negative delta H, and these proteins are involved in signal transduction. There has been no report on direct estimation of binding delta H of anesthetics to proteins. This study used isothermal titration calorimetry to analyze chloroform binding to bovine serum albumin. The calorimetrically measured delta H cal was -10.37 kJ.mol-1. Thus the negative delta H of anesthetic binding is not limited to signal transduction proteins. The binding was saturable following Fermi-Dirac statistics and is characterized by the Langmuir adsorption isotherms, which is interfacial. The high-affinity association constant, K, was 2150 +/- 132 M-1 (KD = 0.47 mM) with the maximum binding number, Bmax = 3.7 +/- 0.2. The low-affinity K was 189 +/- 3.8 M-1 (KD = 5.29 mM), with a Bmax of 13.2 +/- 0.3. Anesthetic potency is a function of the activity of anesthetic molecules, not the concentration. Because the sign of delta H determines the temperature dependence of distribution of anesthetic molecules, it is irrelevant to the temperature dependence of anesthetic potency. PMID:9083685

Ueda, I; Yamanaka, M



Real-Time Monitoring of Membrane-Protein Reconstitution by Isothermal Titration Calorimetry  

PubMed Central

Phase diagrams offer a wealth of thermodynamic information on aqueous mixtures of bilayer-forming lipids and micelle-forming detergents, providing a straightforward means of monitoring and adjusting the supramolecular state of such systems. However, equilibrium phase diagrams are of very limited use for the reconstitution of membrane proteins because of the occurrence of irreversible, unproductive processes such as aggregation and precipitation that compete with productive reconstitution. Here, we exemplify this by dissecting the effects of the K+ channel KcsA on the process of bilayer self-assembly in a mixture of Escherichia coli polar lipid extract and the nonionic detergent octyl-?-d-glucopyranoside. Even at starting concentrations in the low micromolar range, KcsA has a tremendous impact on the supramolecular organization of the system, shifting the critical lipid/detergent ratios at the onset and completion of vesicle formation by more than 2-fold. Thus, equilibrium phase diagrams obtained for protein-free lipid/detergent mixtures would be misleading when used to guide the reconstitution process. To address this issue, we demonstrate that, even under such nonequilibrium conditions, high-sensitivity isothermal titration calorimetry can be exploited to monitor the progress of membrane-protein reconstitution in real time, in a noninvasive manner, and at high resolution to yield functional proteoliposomes with a narrow size distribution for further downstream applications. PMID:24354292



Isothermal Titration Calorimetry in Nanoliter Droplets with Sub-Second Time Constants  

PubMed Central

We reduced the reaction volume in microfabricated suspended-membrane titration calorimeters to nanoliter droplets and improved the sensitivities to below a nanowatt with time constants of around 100ms, The device performance was characterized using exothermic acid-base neutralizations and a detailed numerical model. The finite element based numerical model allowed us to determine the sensitivities within 1% and the temporal dynamics of the temperature rise in neutralization reactions as a function of droplet size. The model was used to determine the optimum calorimeter design (membrane size and thickness, junction area, and thermopile thickness) and sensitivities for sample volumes of 1 nl for silicon nitride and polymer membranes. We obtained a maximum sensitivity of 153 pW/?Hz for a 1 ?m SiN membrane and 79 pW/?Hz for a 1 ?m polymer membrane. The time constant of the calorimeter system was determined experimentally by using a pulsed laser to increase the temperature of nanoliter sample volumes. For a 2.5 nanoliter sample volume, we experimentally determined a noise equivalent power of 500 pW/?Hz and a 1/e time constant of 110ms for a modified commercially available infrared sensor with a thin-film thermopile. Furthermore, we demonstrated detection of 1.4 nJ reaction energies from injection of 25 pl of 1 mM HCl into a 2.5 nl droplet of 1 mM NaOH. PMID:21913688

Lubbers, Brad; Baudenbacher, Franz



The galaxy population of Abell 1367: photometric and spectroscopic data  

NASA Astrophysics Data System (ADS)

Aims: Photometric and spectroscopic observations of the galaxy population of the galaxy cluster Abell 1367 have been obtained, over a field of 34' × 90', covering the cluster centre out to a radius of ~2.2 Mpc. Optical broad- and narrow-band imaging was used to determine galaxy luminosities, diameters and morphologies, and to study current star formation activity of a sample of cluster galaxies. Near-infrared imaging was obtained to estimate integrated stellar masses, and to aid the determination of mean stellar ages and metallicities for the future investigation of the star formation history of those galaxies. Optical spectroscopic observations were also taken, to confirm cluster membership of galaxies in the sample through their recession velocities. Methods.U, B and R broad-band and H? narrow-band imaging observations were carried out using the Wide Field Camera (WFC) on the 2.5 m Isaac Newton Telescope on La Palma, covering the field described above. J and K near-infrared imaging was obtained using the Wide Field Camera (WFCAM) on the 3.8 m UK Infrared Telescope on Mauna Kea, covering a somewhat smaller field of 0.75 square degrees on the cluster centre. The spectroscopic observations were carried out using a multifibre spectrograph (WYFFOS) on the 4.2 m William Herschel Telecope on La Palma, over the same field as the optical imaging observations. Results: Our photometric data give optical and near-infrared isophotal magnitudes for 303 galaxies in our survey regions, down to stated diameter and B-band magnitude limits, determined within R24 isophotal diameters. Our spectroscopic data of 328 objects provide 84 galaxies with detections of emission and/or absorption lines. Combining these with published spectroscopic data gives 126 galaxies within our sample for which recession velocities are known. Of these, 72 galaxies are confirmed as cluster members of Abell 1367, 11 of which are identified in this study and 61 are reported in the literature. H? equivalent widths and fluxes are presented for all cluster galaxies with detected line emission. Conclusions: Spectroscopic and photometric data are presented for galaxies in the nearby cluster Abell 1367, as the first stage of a study of their stellar population and star formation properties. Based on observations made with the Isaac Newton Telescope and the William Herschel Telescope, operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias and the United Kingdom Infra-Red Telescope operated on Mauna Kea, Hawaii by the Joint Astronomy Centre.Tables 8-11 are also available in electronic form at the CDS via anonymous ftp to ( or via

Kriwattanawong, W.; Moss, C.; James, P. A.; Carter, D.




SciTech Connect

We describe the photometric calibration and stellar classification methods used by the Stellar Classification Project to produce the Kepler Input Catalog (KIC). The KIC is a catalog containing photometric and physical data for sources in the Kepler mission field of view; it is used by the mission to select optimal targets. Four of the visible-light (g, r, i, z) magnitudes used in the KIC are tied to Sloan Digital Sky Survey magnitudes; the fifth (D51) is an AB magnitude calibrated to be consistent with Castelli and Kurucz (CK) model atmosphere fluxes. We derived atmospheric extinction corrections from hourly observations of secondary standard fields within the Kepler field of view. For these filters and extinction estimates, repeatability of absolute photometry for stars brighter than magnitude 15 is typically 2%. We estimated stellar parameters {l_brace}T{sub eff}, log (g), log (Z), E{sub B-V}{r_brace} using Bayesian posterior probability maximization to match observed colors to CK stellar atmosphere models. We applied Bayesian priors describing the distribution of solar-neighborhood stars in the color-magnitude diagram, in log (Z), and in height above the galactic plane. Several comparisons with samples of stars classified by other means indicate that for 4500 K {<=}T{sub eff} {<=} 6500 K, our classifications are reliable within about {+-}200 K and 0.4 dex in log (g) for dwarfs, with somewhat larger log (g) uncertainties for giants. It is difficult to assess the reliability of our log (Z) estimates, but there is reason to suspect that it is poor, particularly at extreme T{sub eff}. Comparisons between the CK models and observed colors are generally satisfactory with some exceptions, notably for stars cooler than 4500 K. Of great importance for the Kepler mission, for T{sub eff} {<=} 5400 K, comparison with asteroseismic results shows that the distinction between main-sequence stars and giants is reliable with about 98% confidence. Larger errors in log (g) occur for warmer stars, for which our filter set provides inadequate gravity diagnostics. The KIC is available through the MAST data archive.

Brown, Timothy M. [Las Cumbres Observatory Global Telescope, Goleta, CA 93117 (United States); Latham, David W.; Esquerdo, Gilbert A. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Everett, Mark E., E-mail:, E-mail:, E-mail:, E-mail: [National Optical Astronomy Observatories, Tucson, AZ 85721 (United States)



Predicting Fundamental Stellar Parameters from Photometric Light Curves  

NASA Astrophysics Data System (ADS)

We present a new machine learning based framework for the prediction of the fun- damental stellar parameters, Teff, logg, and [Fe/H], based on the photometric light curves of variable stellar sources. The method was developed following a systematic spectroscopic survey of stellar variability. Variable sources were selected from re- peated Sloan Digital Sky Survey (SDSS) observations of Stripe 82, and spectroscopic observations were obtained with Hectospec on the 6.5-m Multi-Mirror Telescope. In sum, spectra were obtained for ˜9,000 stellar variables (including ˜3,000 from the SDSS archive), for which we measured Teff, log g, and [Fe/H] using the Segue Stellar Parameters Pipeline (SSPP). Examining the full sample of ˜67,000 variables in Stripe 82, we show that the vast majority of photometric variables are consistent with main-sequence stars, even after restricting the search to high galactic latitudes. From the spectroscopic sample we confirm that most of these stellar variables are G and K dwarfs, though there is a bias in the output of the SSPP that prevents the identification of M type variables. We are unable to identify the dominant source of variability for these stars, but eclipsing systems and/or star spots are the most likely explanation. We develop a machine learning model that can determine Teff , log g, and [Fe/H] without obtaining a spectrum. Instead, the random forest regression model uses SDSS color information and light curve features to infer stellar properties. We detail how the feature set is pruned and the model is optimized to produce final predictions of Teff, log g, and [Fe/H] with a typical scatter of 165 K, 0.42 dex, and 0.33 dex, respectively. We further show that for the subset of variables with at least 50 observations in the g band the typical scatter reduces to 75 K, 0.19 dex, and 0.16 dex, respectively. We consider these results an important step on the path to the efficient and optimal extraction of information from future time-domain experiments, such as the Large Survey Synoptic Telescope. We argue that this machine learning framework, for which we outline future possible improvements, will enable the construction of the most detailed maps of the Milky Way ever created.

Miller, A.


Predicting Fundamental Stellar Parameters From Photometric Light Curves  

NASA Astrophysics Data System (ADS)

We present a new machine-learning-based framework for the prediction of the fundamental stellar parameters, Teff, log g, and [Fe/H], based on the photometric light curves of variable stellar sources. The method was developed following a systematic spectroscopic survey of stellar variability. Variable sources were selected from repeated Sloan Digital Sky Survey (SDSS) observations of Stripe 82, and spectroscopic observations were obtained with Hectospec on the 6.5-m Multi-Mirror Telescope. In sum, spectra were obtained for ~9000 stellar variables (including ~3000 from the SDSS archive), for which we measured Teff, log g, and [Fe/H] using the Segue Stellar Parameters Pipeline (SSPP). Examining the full sample of ~67k variables in Stripe 82, we show that the vast majority of photometric variables are consistent with main-sequence stars, even after restricting the search to high galactic latitudes. From the spectroscopic sample we confirm that most of these stellar variables are G and K dwarfs, though there is a bias in the output of the SSPP that prevents the identification of M type variables. We are unable to identify the dominant source of variability for these stars, but eclipsing systems and/or star spots are the most likely explanation. We develop a machine-learning model that can determine Teff, log g, and [Fe/H] without obtaining a spectrum. Instead, the random-forest-regression model uses SDSS color information and light-curve features to infer stellar properties. We detail how the feature set is pruned and the model is optimized to produce final predictions of Teff, log g, and [Fe/H] with a typical scatter of 165 K, 0.42 dex, and 0.33 dex, respectively. We further show that for the subset of variables with at least 50 observations in the g band the typical scatter reduces to 75 K, 0.19 dex, and 0.16 dex, respectively. We consider these results an important step on the path to the efficient and optimal extraction of information from future time-domain experiments, such as the Large Survey Synoptic Telescope. We argue that this machine-learning framework, for which we outline future possible improvements, will enable the construction of the most detailed maps of the Milky Way ever created.

Miller, Adam; Richards, J.; Bloom, J. S.; a larger Team



The unfolding enthalpy of the pH 4 molten globule of apomyoglobin measured by isothermal titration calorimetry.  

PubMed Central

The unfolding enthalpy of the pH 4 molten globule from sperm whale apomyoglobin has been measured by isothermal titration calorimetry, using titration to acid pH. The unfolding enthalpy is close to zero at 20 degrees C, in contrast both to the positive values expected for peptide helices and the negative values reported for holomyoglobin and native apomyoglobin. At 20 degrees C, the hydrophobic interaction should make only a small contribution to the unfolding enthalpy according to the liquid hydrocarbon model. Our result indicates that some factor present in the unfolding enthalpies of native proteins makes the unfolding enthalpy of the pH 4 molten globule less positive than expected from data for peptide helices. PMID:10933499

Jamin, M.; Antalik, M.