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1

Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System  

PubMed Central

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

Garcia, Ausberta Jesus Cabezas; Reis, Boaventura F.

2006-01-01

2

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.

1955-01-01

3

Determination of polyhexamethylene biguanide hydrochloride using photometric colloidal titration with crystal violet as a color indicator.  

PubMed

A solution of polyhexamethylene biguanide hydrochloride (PHMB-HCl) was titrated with a standard solution of potassium poly(vinyl sulfate) (PVSK) using crystal violet (CV) as an photometric indicator cation. The end point was detected by a sharp absorbance change due to an abrupt decrease in the concentration of CV. A linear relationship between the concentration of PHMB-HCl and the end-point volume of the titrant existed in the concentration range from 2 to 10 × 10(-6) eq mol L(-1). Back-titration was based on adding an excess amount of PVSK to a sample solution containing CV, which was titrated with a standard solution of poly(diallyldimethylammonium chloride) (PDADMAC). The calibration curve of the PHMB-HCl concentration to the end point volume of the titrant was also linear in the concentration range from 2 to 8 × 10(-6) eq mol L(-1). Both photometric titrations were applied to the determination of PHMB-HCl in a few contact-lens detergents. Back-titration showed a clear end point, but direct titration showed an unclear end point. The results of the back-titration of PHMB-HCl were compared with the content registered in its labels. PMID:21828919

Masadome, Takashi; Miyanishi, Takaaki; Watanabe, Keita; Ueda, Hiroshi; Hattori, Toshiaki

2011-01-01

4

Titration  

NSDL National Science Digital Library

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.

David Smith

5

Titration  

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

6

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

ERIC Educational Resources Information Center

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

Porritt, M.; Poling, A.

2008-01-01

7

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

PubMed

The enthalpy changes associated with the protonation and deprotonation of an alumina surface have been determined on the basis of microcalorimetry experiments and acid-base potentiometric titrations at 25 degrees C. It has been shown that the results may vary significantly according to the experimental procedure. In order to do so, the potentiometric and microcalorimetric titrations have been carried out first from an acidic pH to basic pH and second from a pH near the pH(zpc) of alumina to acidic or basic pH. It has been demonstrated that the pK(a) values deduced from the potentiometric titrations are the same whatever the experimental protocol whereas the only way to obtain meaningful enthalpies of proton exchange is to carry out microcalorimetric titrations by starting around the point of zero charge. PMID:19643428

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

2009-10-01

8

Free-operant and auto-titration brain self-stimulation procedures in the rat: a comparison of drug effects.  

PubMed

Rats were implanted with bipolar stimulating electrodes aimed at the medial forebrain bundle of the lateral hypothalamus, and trained to press a lever in one of two different procedures in order to receive electrical stimulation through the electrodes. In a free-operant procedure, each response produced a 200 msec train of electric pulses at a suprathreshold current, the intensity of which remained constant throughout the session. In an auto-titration procedure, each response produced an electrical stimulus which was initially set at a suprathreshold intensity. Every 15th response reduced the stimulation current by 3 muA. The animal could reset the current to its initial intensity at any time by pressing a second lever in the test chamber. The average current at which the animal pressed the reset lever was defined as the reinforcement threshold. Dose-response functions were determined for d- and l-amphetamine, alpha-methyltyrosine, and haloperidol. The reinforcement threshold was decreased by both d- and l-amphetamine, increased by haloperidol, and not changed by alpha-methyltyrosine. These effects on reinforcement threshold were not consistently related to the drug-induced changes in response rate in either procedure. The auto-titration procedure may be useful for distinguishing between drugs which cause nonspecific changes in the rate of ongoing behavior and those which specifically modify the reinforcement efficacy of brain stimulation. PMID:441089

Schaefer, G J; Holtzman, S G

1979-01-01

9

Application of a new multivariate curve resolution procedure to the simultaneous analysis of several spectroscopic titrations of the copper(II)—polyinosinic acid system  

Microsoft Academic Search

The acid-base properties and the copper(II)-complexing behaviour of the polynucleotide polyinosinic acid have been studied by means of potentiometric and spectrophotometric titrations. Spectrophotometric data have been treated with a new multivariate curve resolution procedure that allows to analyze simultaneously different sets of spectroscopic titrations of the same multi-equilibria system. The results obtained give a real proof of the advantages of

R. Tauler; A. Izquierdo-Ridorsa; R. Gargallo; E. Casassas

1995-01-01

10

Titration Techniques  

NASA Astrophysics Data System (ADS)

Significant attention is paid to the proper technique for reading a meniscus. Video shows meniscus-viewing techniques for colorless and dark liquids and the consequences of not reading a meniscus at eye level. Lessons are provided on approaching the end point, focusing on end point colors produced via different commonly used indicators. The concept of a titration curve is illustrated by means of a pH meter. Carefully recorded images of the entire range of meniscus values in a buret, pipet, and graduated cylinder are included so that you can show your students, in lecture or pre-lab discussion, any meniscus and discuss how to read the buret properly. These buret meniscus values are very carefully recorded at the rate of one video frame per hundredth of a milliliter, so that an image showing any given meniscus value can be obtained. These images can be easily incorporated into a computer-based multimedia environment for testing or meniscus-reading exercises. Two of the authors have used this technique and found the exercise to be very well received by their students. Video on side two shows nearly 100 "bloopers", demonstrating both the right way and wrong ways to do tasks associated with titration. This material can be used in a variety of situations: to show students the correct way to do something; to test students by asking them "What is this person doing wrong?"; or to develop multimedia, computer-based lessons. The contents of Titration Techniques are listed below: Side 1 Titration: what it is. A simple titration; Acid-base titration animation; A brief redox titration; Redox titration animation; A complete acid-base titration. Titration techniques. Hand technique variations; Stopcock; Using a buret to measure liquid volumes; Wait before reading meniscus; Dirty and clean burets; Read meniscus at eye level (see Fig. 1); Meniscus viewing techniques--light colored liquids; Meniscus viewing techniques--dark liquids; Using a magnetic stirrer; Rough titration; Significant figures; Approaching the end point; End point colors; Titration with a pH meter; Titration curves; Colors of indicators. Meniscus values. Buret meniscus values; Pipet meniscus values; Graduated cylinder meniscus values. Side 2"Bloopers". Introducing the people; Titration animation; Inspecting the buret; Rinsing the buret with water; Preparing a solid sample; Obtaining a liquid sample; Delivering a liquid sample with a Mohr pipet; Pipetting a liquid sample with a Mohr pipet; Rinsing the Mohr pipet with sample; Using the Mohr pipet to transfer sample; Delivering a liquid sample with a volumetric pipet; Pipetting a liquid sample with a volumetric pipet; Rinsing the volumetric pipet with sample; Using the volumetric pipet to transfer sample; Obtaining the titrant; Rinsing the buret with titrant; Filling the buret with titrant; Adding the indicator; The initial reading; Beginning the titration; Delivering titrant; The final reading. Figure 3. Near the end point a single drop of titrant can cause a lasting color change.

Jacobsen, Jerrold J.; Houston Jetzer, Kelly; Patani, Néha; Zimmerman, John; Zweerink, Gerald

1995-07-01

11

Titration Techniques  

Microsoft Academic Search

Significant attention is paid to the proper technique for reading a meniscus. Video shows meniscus-viewing techniques for colorless and dark liquids and the consequences of not reading a meniscus at eye level. Lessons are provided on approaching the end point, focusing on end point colors produced via different commonly used indicators. The concept of a titration curve is illustrated by

Jerrold J. Jacobsen; Kelly Houston Jetzer; Néha Patani; John Zimmerman; Gerald Zweerink

1995-01-01

12

Microscale Titration in Schools Titration Competition.  

ERIC Educational Resources Information Center

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

Clark, Michael J.

1998-01-01

13

ChemTeacher: Titration  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Titration page includes resources for teaching students about the theory and applications of titrations.

2012-07-24

14

ACIDBASE TITRATION NUMERICAL SIMULATOR  

Microsoft Academic Search

The analytical methods of qualitative and quantitative determination of ions in solutions are very flexible to automation. The present work is focus on modeling the process of titration and presents a numerical simulation of acid-base titration. A PHP program to compute all iterations in titration process that solves a 3 rd rank equation to find value of pH for was

Lorentz JÄNTSCHI; Delia GLIGOR; Mihaela Ligia

2003-01-01

15

Titration (ChemPages Lab)  

NSDL National Science Digital Library

Titration: this is a resource in the collection "ChemPages Laboratory Resources". A titration is a laboratory procedure for quantitative analysis. Titrametric analysis is used to determine the concentration of an analyte in solution, the stoichiometry of a reaction, the number of electrons gained or accepted in a redox reaction and the solubility products. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.

16

A hot-cell titration system  

SciTech Connect

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

Klatt, L.N.

1988-07-01

17

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)

2002-01-01

18

Simple sensor for potentiometric titrations  

SciTech Connect

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

Selig, W.

1982-01-01

19

Acid Rain Analysis by Standard Addition Titration.  

ERIC Educational Resources Information Center

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

Ophardt, Charles E.

1985-01-01

20

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

1986-01-01

21

pH Static Titration: A Quasistatic Approach  

ERIC Educational Resources Information Center

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

Michalowski, Tadeusz; Toporek, Marcin; Rymanowski, Maciej

2007-01-01

22

Linear titration plots for polyfunctional weak acids and bases.  

PubMed

Procedures are derived for obtaining the equivalence volumes in the potentiometric titrations of polyfunctional weak acids and weak bases by a linear titration plot method. The effect of errors in the equilibrium constants on the accuracy is considered. A Fortran program is available to do the calculations. PMID:18961862

Midgley, D; McCallum, C

1976-04-01

23

Calculation of titratable acidity from urinary stone risk factors  

Microsoft Academic Search

Calculation of titratable acidity from urinary stone risk factors. Using urine samples and standard solutions, this study demonstrates that the existing procedure for measuring titratable acidity in the urine is not reliable and may result in overestimates of up to 25%. The accuracy is affected by loss of CO2, the presence of uric acid crystals, and the precipitation of calciumphosphate

Dirk J Kok; John Poindexter; Charles Y C Pak

1993-01-01

24

Filtrates & Residues: Olfactory Titration.  

ERIC Educational Resources Information Center

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

Wood, John T.; Eddy, Roberta M.

1996-01-01

25

Spectrophotometric titration of zirconium in siliceous materials.  

PubMed

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

26

Titration Curves: Fact and Fiction.  

ERIC Educational Resources Information Center

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

Chamberlain, John

1997-01-01

27

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

PubMed

Influenza antigens can be detected by several well established methods. However, when it is important to determine the titre of infective virions, a bioassay should be employed. The standard and the most widely used tests for influenza infectivity are titration carried out in embryonated hen eggs, or the plaque assay employing tissue culture techniques. A simple colourimetric assay for influenza virus detection and titration is described. Samples of allantoic fluid or mice lung homogenates were used to infect MDCK cultures in microplate wells. After an incubation period, the tetrazolium (MTT) colourimetric assay was used to determine cell viability, and when compared to untreated culture control enabled the detection and titration of several influenza strains. When samples were assayed simultaneously in embryonated eggs and by the MCVT method, good correlation in determined titres was obtained. The availability of an additional method for influenza titration allows more flexibility in the choice of titration method according to the specific needs of the study. Furthermore, this method lends itself to full automatization. Similar procedures should also be applicable to titration of other cytopathic viruses. PMID:7769039

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

1995-03-01

28

Acid–base titration curves of solid humic acids  

Microsoft Academic Search

A direct discontinuous titration method with NaOH was developed to characterize the acid–base properties of complex natural polyelectrolytes, such as humic substances (HS). The classical batch procedure, suggested originally for examinations of resin-based ion exchanger, was modified to be applicable to HS; the modified method is suitable especially for the measurements of the titration curves of solid humic acids (HA).

Pavel Janoš; Sylvie K?íženecká; Libuše Madronová

2008-01-01

29

Determination of protonation constants by coulometric titration.  

PubMed

Application of coulometric titration to the determination of the protonation constants of acids and bases offers several advantages because of its simplicity, precision and accuracy. This procedure is rapid and requires only one calibration solution of strong acid in the same solvent and at the same ionic strength as the solution of acid (or base) being investigated. The procedure seems to be especially advantageous in the case of non-aqueous or mixed solvents having amphiprotic character. The validity of the method has been checked with several substances in water, 95% ethanol and ethylene glycol. PMID:18964325

G?ab, S; Skrzydlewska, E; Hulanicki, A

1987-04-01

30

APAP and Alternative Titration Methods.  

PubMed

PURPOSE OF REVIEW: Positive airway pressure therapy (PAP) is commonly prescribed treatment for obstructive sleep apnea (OSA). Traditionally, the determination of the optimal pressure for treatment of sleep-disordered breathing was made by manual titration of the device by a sleep technician in attendance during polysomnography. However, the advent of alternative methods for determination of optimal PAP - such as auto-titrating PAP (APAP) - has seen tremendous growth over the past decade. The purpose of this review is to improve our understanding of the currently available alternative methods for titration of PAP in patients with sleep-disordered breathing (SDB) with special emphasis on obstructive sleep apnea. RECENT FINDINGS: Recent prospective-randomized studies of alternative methods of titration suggest that pressure determinations made by such devices are comparable to traditional manual titrations made in the sleep laboratory. Obstacles to the adoption of such alternative modes of titration into day-to-day practice may be attributable to issues surrounding appropriate patient selection, differences between devices, re-imbursement policies of third party payors, consensus amongst sleep experts, and individual physicians' practice patterns and volumes. While newer generations and types of auto-titrating PAP devices are entering the sleep field constantly, providers' knowledge and time availability remain limiting factors. SUMMARY: There is tremendous growth in the technology and scientific evidence in support of alternative modes of PAP titration for sleep-disordered breathing, but barriers to implementation remain. PMID:20806054

Ahmed, Omer; Parthasarathy, Sairam

2010-09-01

31

APAP and Alternative Titration Methods  

PubMed Central

Purpose of review Positive airway pressure therapy (PAP) is commonly prescribed treatment for obstructive sleep apnea (OSA). Traditionally, the determination of the optimal pressure for treatment of sleep-disordered breathing was made by manual titration of the device by a sleep technician in attendance during polysomnography. However, the advent of alternative methods for determination of optimal PAP – such as auto-titrating PAP (APAP) – has seen tremendous growth over the past decade. The purpose of this review is to improve our understanding of the currently available alternative methods for titration of PAP in patients with sleep-disordered breathing (SDB) with special emphasis on obstructive sleep apnea. Recent Findings Recent prospective-randomized studies of alternative methods of titration suggest that pressure determinations made by such devices are comparable to traditional manual titrations made in the sleep laboratory. Obstacles to the adoption of such alternative modes of titration into day-to-day practice may be attributable to issues surrounding appropriate patient selection, differences between devices, re-imbursement policies of third party payors, consensus amongst sleep experts, and individual physicians’ practice patterns and volumes. While newer generations and types of auto-titrating PAP devices are entering the sleep field constantly, providers’ knowledge and time availability remain limiting factors. Summary There is tremendous growth in the technology and scientific evidence in support of alternative modes of PAP titration for sleep-disordered breathing, but barriers to implementation remain. PMID:20806054

Ahmed, Omer; Parthasarathy, Sairam

2010-01-01

32

Interference by acetylated aminoacetic acid in nonaqueous titration of nicotinic acid.  

PubMed

A nonaqueous titration procedure is described for determining aminoacetic acid and nicotinic acid in mixtures and elixirs. The effect of acetylated aminoacetic acid on the potentiometric titration of nicotinic acid is discussed. Above a 2:1 ration of aminoacetic acid to nicotinic acid, the former interferes with titration. The titration curve of nicotinic acid becomes progressively flatter with increasing amounts of the acetylated compound. Above this ratio, nicotinic acid had to be separated from the mixture by dissolving in ethanol for a successful titration. PMID:893322

Soliman, S A; Abdine, H; Morcos, M G

1977-09-01

33

Comparison of salt titration and potentiometric titration methods for the determination of Zero Point of Charge (ZPC)  

Microsoft Academic Search

The salt titration (ST) method was evaluated as a method to determine ZPC in comparison with the potentiometric titration (PT) method for 26 soils with variable charge clays, i.e., Oxisols and Ultisols from Thailand and Andisols from Japan. In addition to the determination of ST-pH0 as the zero point of charge, a calculation procedure (STPT method) was adopted here in

Katsutoshi Sakurai; Yohichi Ohdate; Kazutake Kyuma

1988-01-01

34

Titrating-Delay Matching-to-Sample in the Pigeon  

ERIC Educational Resources Information Center

The titrating-delay matching-to-sample (TDMTS) procedure offers researchers an additional behavioral task thought to capture some important features of remembering. In this procedure, the delay between sample offset and comparison onset adjusts as a function of the subject's performance. Specifically, correct matches increase the delay and…

Kangas, Brian D.; Vaidya, Manish; Branch, Marc N.

2010-01-01

35

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.

2012-01-01

36

Characterization of petroleum sulfonates by a nonaqueous titration method  

SciTech Connect

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 calculated from the grams of sample titrated and the moles of acid used. The potentiometric titration can be carried out in less than 10 minutes and can be done with 10 to 100 mg of sample. The accuracy and precision of the procedure were examined by the titration of sodium salts of p-toluene sulfonate, 2-naphthalene sulfonate, and petroleum sulfonates. In general, values for the equivalent weight were within 2% of those values determined by the Epton titration, by wet ashing methods, or from the theoretical value. The relative standard deviation (RSD) for the procedure is estimated to be 0.5%. For p-toluene sulfonate, an RSD of 0.15% was calculated. Petroleum sulfonates are used to liberate a residual oil from a porous medium in a tertiary oil-recovery process. 24 refs.

Voss, K.R.; Bricker, C.E.; Michnick, M.J.; Willhite, G.P.

1981-12-01

37

Amperometric, Bipotentiometric, and Coulometric Titration.  

ERIC Educational Resources Information Center

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

Stock, John T.

1980-01-01

38

ANTIBODY TITRATION PROTOCOL NOTE: When titrating an antibody for use in flow cytometry, you should  

E-print Network

ANTIBODY TITRATION PROTOCOL NOTE: When titrating an antibody for use in flow cytometry, you should attempt to titrate it under the same conditions in which it will be used during your experimental cell're titrating. You should titrate each new vial of antibody you receive in your lab, even if you've used

Oliver, Douglas L.

39

Determination of Acidity Constants by Gradient Flow-Injection Titration  

ERIC Educational Resources Information Center

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

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

2006-01-01

40

Modeling and Graphic Presentation of Acid–Base Titration Curves. Presentation of an Alternative Method  

Microsoft Academic Search

Titration curves for the acid—base–titration of polyvalent acids and bases and their mixtures can be created in a simple way and presented graphically. The method, an alternative to the existing procedures, shall be presented here for discussion. With the described method it is possible in an easy manner and for didactic purposes to show how the boundary conditions, such as

Günter Heil; Horst Schäfer

2002-01-01

41

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.

1984-01-01

42

High-sensitivity titration microcalorimeter  

NASA Astrophysics Data System (ADS)

A differential titration microcalorimeter for studying intermolecular interactions in solutions has been designed. To increase the speed of the instrument, the dynamic correction method has been used. It has been shown that electrical calibration of the microcalorimeter is consistent with its chemical calibration. The use of the instrument for measuring the integral heats of dilution of 1-propanol has been demonstrated.

Velikov, A. A.; Grigoryev, S. V.; Chuikin, A. V.

2015-02-01

43

Polyelectrolyte Titration: Theory and Experiment  

E-print Network

Titration of methacrylic acid / ethyl-acrylate copolymers is studied experimentally and theoretically. At low salt concentrations, this polyacid exhibits a plateau in the titration curve below the neutralization point. The plateau has been often attributed to a first-order phase transition associated with polymer conformational changes. We argue that the specific shape of titration curves of hydrophobic polyelectrolytes is due to electrostatics and does not necessarily require a conformation change of the polyelectrolyte chains. We calculate the free energy at the mean-field level and its first-order (one loop) correction using a loop expansion. The latter is dominated by Debye-Huckel--like charge-charge correlations as well as by correlations between dissociation sites along the polymer chain. We show that the one-loop corrections to the free energy lead to titration curves that agree with experiments. In particular, the model explains the decrease of the pH at the plateau when the polymer concentration is increased or when salt is added to the solution.

I. Borukhov; D. Andelman; R. Borrega; M. Cloitre; L. Leibler; H. Orland

2000-05-18

44

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

PubMed

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

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

2015-04-01

45

Titration of chaos with added noise  

PubMed Central

Deterministic chaos has been implicated in numerous natural and man-made complex phenomena ranging from quantum to astronomical scales and in disciplines as diverse as meteorology, physiology, ecology, and economics. However, the lack of a definitive test of chaos vs. random noise in experimental time series has led to considerable controversy in many fields. Here we propose a numerical titration procedure as a simple “litmus test” for highly sensitive, specific, and robust detection of chaos in short noisy data without the need for intensive surrogate data testing. We show that the controlled addition of white or colored noise to a signal with a preexisting noise floor results in a titration index that: (i) faithfully tracks the onset of deterministic chaos in all standard bifurcation routes to chaos; and (ii) gives a relative measure of chaos intensity. Such reliable detection and quantification of chaos under severe conditions of relatively low signal-to-noise ratio is of great interest, as it may open potential practical ways of identifying, forecasting, and controlling complex behaviors in a wide variety of physical, biomedical, and socioeconomic systems. PMID:11416195

Poon, Chi-Sang; Barahona, Mauricio

2001-01-01

46

ChemTeacher Resource: Acid Base Titration  

NSDL National Science Digital Library

Acid-Base titration applet that plots pH changes as student adds acid or base. Gives choice of indicators. Compares plots for titration of traditional solution and a buffered solution. Can alter starting concentrations.

University of Southern California

2011-01-01

47

Titration of an Unknown Acid or Base  

NSDL National Science Digital Library

This website contains a JAVA applet that simulates the titration of an unknown acid or base, and provides a graphical output of the titration curve. The unknown compounds are taken from a list of amino acids. Students set up the parameters of the titration, and then create a simulated pH curve. From this they are able to identify the unknown compound from the list, and determine the acid dissociation constant(s) from the titration data.

Blauch, David N.

48

Alternative methods for titratable acidity determination  

Microsoft Academic Search

Methods for determination of titratable acidity, other than traditional titration, i.e. methods without titration, are considered. A number of them use analytical acid-base reagents which quickly convert a mixture of strong and weak acids into a new system. This conversion makes it possible to obtain directly the analytical signal (pH, optical density, etc.) for titratable acidity calculation. These methods in

O. Yu. Berezin; Ya. I. Tur'yan; I. Kuselman; A. Shenhar

1995-01-01

49

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

ERIC Educational Resources Information Center

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

McClendon, Michael

1984-01-01

50

Modeling potentiometric titration behavior of glauconite  

Microsoft Academic Search

Potentiometric titration behavior and the effects of dissolution on the titration experiment of a complex natural clay mineral, glauconite, were investigated and interpreted according to surface complexation theory. Considerable dissolution was detected in the time frame of the titration experiments, with the amount of individual cations released from glauconite a function of solution variables and dissolution kinetics. Dissolution effects can

Weiping Lu; Edward H. Smith

1996-01-01

51

Colorblindness and Titrations with Visual Indicators.  

ERIC Educational Resources Information Center

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

Diehl, Harvey; And Others

1985-01-01

52

Optimization of a novel two-phase potentiometric titration method of barbiturates with mercury (II). Part II: Experimental evaluation.  

PubMed

A two-phase potentiometric titration procedure of barbiturates with mercury(II) was developed. The composition of the formed mercury-barbiturate complexes was elucidated by infrared spectrometry. In the new titration procedure the barbituric acid derivative is dissolved in an aqueous borate buffer. An organic phase consisting of chloroform and benzyl alcohol is added, and the vigorously stirred contents of the titration vessel are titrated by a mercury(II) nitrate solution. In the potentiometric determination of the end-point a rotating mercury electrode is used as an indicator electrode that also serves as an efficient stirrer. The two-phase procedure was compared with a one-phase mercurimetric potentiometric titration in borate buffer and with the potentiometric titration by sodium hydroxide in an ethanol-water solution. The proposed two-phase procedure is superior to both methods because lower concentrations of barbiturates (10(-3) - 10(-4) M) can be determined successfully. The one-phase procedure suffers from systematic errors, while the titration with sodium hydroxide is less precise at concentration levels of the barbiturates prevailing in content uniformity studies. By the two-phase procedure the direct titration of phenobarbital and mephobarbital in a dry mix of tablet excipients was possible with a relative standard deviation smaller than 1.5 percent. PMID:6646992

Coenegracht, P M; Metting, H J; Doornbos, D A

1983-10-21

53

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

PubMed

Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness. PMID:25224566

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

2015-04-01

54

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

PubMed

New iterative methods for analysis of potentiometric titration data of (a) mixtures of weak monoprotic acids with their conjugate bases, (b) solutions of polyprotic (di- and triprotic) acids, and (c) mixtures of two diprotic acids are presented. These methods, using data exclusively resulting from the acidic region of the titration curve permits the accurate determination of the analytical concentration of one or more acids even if the titration is stopped well before the end point of the titration. For the titration of a solution containing a conjugate acid/base pair, the proposed procedure enables the extraction of the initial composition of the mixture, as well as the dissociation constant of the concerned acid. Thus, it is possible by this type of analysis to distinguish whether a weak acid has been contaminated by a strong base and define the extent of the contamination. On the other hand, for the titration of polyprotic acids, the proposed approach enables the extraction of the accurate values of the equivalence volume and the dissociation constants K(i) even when the ionization stages overlap. Finally, for the titration of a mixture of two diprotic acids the proposed procedure enables the determination of the composition of the mixture even if the sum of the concentrations of the acids is not known. This method can be used in the analysis of solutions containing two diastereoisomeric forms of a weak diprotic acid. The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable even when the titration data are considerably obscured by 'noise' or contain an important systematic error. The proposed procedures were also successfully applied to experimental titration data. PMID:18966298

Papanastasiou, G; Ziogas, I

1995-06-01

55

Precipitation titration of perchlorate using new titrants  

SciTech Connect

We have evaluated the following new titrants for the potentiometric precipitation titration of perchlorate: cetyltrimethylammonium chloride (CETAC), cetyltrimethylammonium bromide (CETAB), cetylpyridinium chloride (CPC), and benzyldimethyltetradecylammonium chloride (BDTAC). Titrations were monitored with a fluoroborate ion-selective electrode (ISE) and a double-junction reference electrode. The titration system was controlled by a Tektronix 4051 graphics system. The perchlorate, nitrate, and calcium ISE may also be used to monitor emf's. 7 tables, 2 figures.

Selig, W.

1980-05-01

56

pH and Titratable Acidity  

NASA Astrophysics Data System (ADS)

There are two interrelated concepts in food analysis that deal with acidity: pH and titratable acidity. Each of these quantities is analytically determined in separate ways and each has its own particular impact on food quality. Titratable acidity deals with measurement of the total acid concentration contained within a food (also called total acidity). This quantity is determined by exhaustive titration of intrinsic acids with a standard base. Titratable acidity is a better predictor of acid's impact on flavor than pH.

Sadler, George D.; Murphy, Patricia A.

57

Isothermal Titration Calorimetry of RNA  

PubMed Central

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

Salim, Nilshad N.; Feig, Andrew L.

2009-01-01

58

A new titration system of a novel split-type superconducting magnet NMR spectrometer.  

PubMed

A new titration system for studying protein-ligand interactions has been developed. In this system, the sample solution is circulated in the route formed by an access path in a split superconducting magnet to maintain a constant protein concentration during the titration experiments. A concentration-control procedure for the ligand/protein ratio is devised, and the ligand/protein ratio is well controlled by this apparatus. PMID:19123547

Kitagawa, Isao; Tanaka, Hideki; Okada, Michiya; Kitaguchi, Hitoshi; Kohzuma, Takamitsu

2008-12-01

59

Symmetry Properties of Potentiometric Titration Curves.  

ERIC Educational Resources Information Center

Demonstrates how the symmetry properties of titration curves can be efficiently and rigorously treated by means of a simple method, assisted by the use of logarithmic diagrams. Discusses the symmetry properties of several typical titration curves, comparing the graphical approach and an explicit mathematical treatment. (Author/JM)

Macca, Carlo; Bombi, G. Giorgio

1983-01-01

60

A Tabular Approach to Titration Calculations  

ERIC Educational Resources Information Center

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

Lim, Kieran F.

2012-01-01

61

Potentiometric titration of metal ions in ethanol.  

PubMed

The potentiometric titrations of Zn2+, Cu2+ and 12 Ln3+ metal ions were obtained in ethanol to determine the titration constants (defined as the at which the [-OEt]/[Mx+]t ratios are 0.5, 1.5, and 2.5) and in two cases (La3+ and Zn2+) a complete speciation diagram. Several simple monobasic acids and aminium ions were also titrated to test the validity of experimental titration measurements and to establish new constants in this medium that will be useful for the preparation of buffers and standard solutions. The dependence of the titration constants on the concentration and type of metal ion and specific counterion effects is discussed. In selected cases, the titration profiles were analyzed using a commercially available fitting program to obtain information about the species present in solution, including La3+ for which a dimer model is proposed. The fitting provides the microscopic values for deprotonation of one to four metal-bound ethanol molecules. Kinetics for the La3+-catalyzed ethanolysis of paraoxon as a function of are presented and analyzed in terms of La3+ speciation as determined by the analysis of potentiometric titration curves. The stability constants for the formation of Zn2+ and Cu2+ complexes with 1,5,9-triazacyclododecane as determined by potentiometric titration are presented. PMID:16961382

Gibson, Graham T T; Mohamed, Mark F; Neverov, Alexei A; Brown, R S

2006-09-18

62

Linear Titration Curves of Acids and Bases.  

PubMed

The Henderson-Hasselbalch equation, by a simple transformation, becomes pH - pK = pA - pB, where pA and pB are the negative logarithms of acid and base concentrations. Sigmoid titration curves then reduce to straight lines; titration curves of polyelectrolytes, to families of straight lines. The method is applied to the titration of the dipeptide glycyl aminotricarballylic acid, with four titrable groups. Results are expressed as Cartesian and d'Ocagne nomograms. The latter is of a general form applicable to polyelectrolytes of any degree of complexity. PMID:17738750

Joseph, N R

1959-05-29

63

The use of graphite electrodes in potentiometric titrations  

SciTech Connect

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

Selig, W.S.

1987-04-01

64

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

PubMed

A general method for evaluating titration data for mixtures of acids and for acids in mixture with weak bases is presented. Procedures are given that do not require absolute [H]-data, i.e., relative [H]-data may be used. In most cases a very rough calibration of the electrode system is enough. Further, for simple systems, very approximate values of the stability constants are sufficient. As examples, the titration of the following are treated in some detail: a mixture of two acids, a diprotic acid, an acid in presence of its conjugate base, and an ampholyte. PMID:18961983

Pehrsson, L; Ingman, F; Johansson, S

65

Lab on paper: iodometric titration on a printed card.  

PubMed

A paper test card has been engineered to perform an iodometric titration, an application that requires storage and mixing on demand of several mutually incompatible reagents. The titration is activated when a user applies a test solution to the test card: the dried reagents are reconstituted and combined through a surface-tension-enabled mixing (STEM) mechanism. The device quantifies 0.8-15 ppm of iodine atoms from iodate in aqueous solutions. This is useful, for example, to quantify iodine levels in fortified salt. A blinded internal laboratory validation established the accuracy as 1.4 ppm I and the precision as 0.9 ppm I when the test card was read by newly trained users. Using computer software to process images, the accuracy and precision both improved to 0.9 ppm I. The paper card can also detect substandard ? lactam antibiotics using an iodometric back-titration. When used to quantify amoxicillin, good distinction is achieved between solutions that differ by 0.15 mg/mL over a working range of 0-0.9 mg/mL. The test card was designed to meet the World Health Organization ASSURED criteria for use in low resource settings, where laboratory-based analytical procedures are often not available. PMID:25711696

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

2015-04-01

66

A CRITICAL ASSESSMENT OF PHOTOMETRIC REDSHIFT METHODS: A CANDELS INVESTIGATION  

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: dahlen@stsci.edu [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); and others

2013-10-01

67

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

2013-10-01

68

Potentiometric titrations using pencil and graphite sensors  

SciTech Connect

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

Selig, W.S.

1984-01-01

69

Nanopore back titration analysis of dipicolinic acid.  

PubMed

Here, we report a novel label-free nanopore back titration method for the detection of dipicolinic acid, a marker molecule for bacterial spores. By competitive binding of the target analyte and a large ligand probe to metal ions, dipicolinic acid could be sensitively and selectively detected. This nanopore back titration approach should find useful applications in the detection of other species of medical, biological, or environmental importance if their direct detection is difficult to achieve. PMID:25074707

Han, Yujing; Zhou, Shuo; Wang, Liang; Guan, Xiyun

2015-02-01

70

Determination of penicillins by desulphurization with lead and edta titration.  

PubMed

A new, simple, accurate and rapid method is described for the determination of total penicillins in pharmaceutical preparations. The method is based on desulphurization with potassium plumbite whereby one mole of lead sulphide is formed per mole of penicillin. The excess of lead ions is titrated with EDTA at pH 4.5, with use of the lead ion-selective electrode. Results are reproducible within +/- 0.5% and compare favourably with those obtained by the procedures of the United States and British Pharmacopoeias. PMID:18962387

Hassan, S S; Zaki, M T; Eldesouki, M H

1979-02-01

71

Photometric properties of Mars soils analogs  

USGS Publications Warehouse

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

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

2013-01-01

72

LABORATORY EXPERIMENT 5 PRECIPITATION TITRATION WITH SILVER NITRATE.  

E-print Network

solution can be used for various titrations. I. Potentiometric Halide Titration with Ag+ MixturesLABORATORY EXPERIMENT 5 PRECIPITATION TITRATION WITH SILVER NITRATE. The AgNO3 solution (~0.02 M method with adsorption indicator and using Mohr method with chromate indicator. Both titrations

Nazarenko, Alexander

73

LABORATORY EXPERIMENT 6 PRECIPITATION TITRATION WITH SILVER NITRATE.  

E-print Network

LABORATORY EXPERIMENT 6 PRECIPITATION TITRATION WITH SILVER NITRATE. The AgNO3 solution (~0.02 M titrations are to be done in triplicate. I. Standardization of AgNO3 solution 1. The Determination of Chloride by Titration with an Adsorption Indicator Discussion In this titration, the anionic adsorption

Nazarenko, Alexander

74

Title: Titration_DB: Storage and Analysis of NMR-monitored Protein pH Titration Curves  

E-print Network

1 Title: Titration_DB: Storage and Analysis of NMR- monitored Protein pH Titration Curves' pKa values from the titration database for 1 H data........................2 Table 2: List of all ..................................................................................................................................................22 #12;2 Tables Table 1: List of all extracted `primary' pKa values from the titration database for 1

McIntosh, Lawrence P.

75

Potentiometric Titration of Industrial Samples—End-point Detection by Means of Wavelets  

NASA Astrophysics Data System (ADS)

A continuous wavelet transform with a specially defined dedicated mother wavelet is applied for data treatment as a signal-processing tool in a potentiometric titration. The inflection points of the titration curve are localized in one step of the calculations. The imperfection of signal, random noise, or spikes has no influence on the operation of the procedure. The proposed algorithm does not require any prior information about the nature or the type of analyte and/or the shape of the titration curve. Although the optimization of transformation parameters should be done, they may be chosen from a wide interval. The accuracy and precision of the proposed end-point estimation is examined on several simulated curves and instrumental potentiometric titrations. Under normal working conditions, analyte concentrations with variation coefficients between 1% and 5% have been determined. The procedure based on the wavelets provides an objective criterion for the determination of the end point. It can be reproduced and fully automated, thus contributing to a more versatile titration analysis.

Jakubowska, M.; Ba?, B.; Niewiara, E.; Reczy?ski, W.; Kubiak, W. W.

2009-08-01

76

[Sources of error in the European Pharmacopoeia assay of halide salts of organic bases by titration with alkali].  

PubMed

A short overview has been given by the authors on the titrimetric assay methods of halide salts of organic bases in the pharmacopoeias of greatest importance. The alternative procedures introduced by the European Pharmacopoeia Commission some years ago to replace the non-aqueous titration with perchloric acid in the presence of mercuric acetate have also been presented and evaluated. The authors investigated the limits of applicability and the sources of systematic errors (bias) of the strongly preferred titration with sodium hydroxide in an alcoholic medium. To assess the bias due to the differences between the results calculated from the two inflexion points of the titration curves and the two real endpoints corresponding to the strong and weak acids, respectively, the mathematical analysis of the titration curve function was carried out. This bias, generally negligible when the pH change near the endpoint of the titration is more than 1 unit, is the function of the concentration, the apparent pK of the analyte and the ionic product of water (ethanol) in the alcohol-water mixtures. Using the validation data gained for the method with the titration of ephedrine hydrochloride the authors analysed the impact of carbon dioxide in the titration medium on the additive and proportional systematic errors of the method. The newly introduced standardisation procedure of the European Pharmacopoeia for the sodium hydroxide titrant to decrease the systematic errors caused by carbon dioxide has also been evaluated. PMID:11379027

Kószeginé, S H; Ráfliné, R Z; Paál, T; Török, I

2000-01-01

77

The MUNI Photometric Archive  

NASA Astrophysics Data System (ADS)

In the 1990s of the last century, CCD cameras became more reachable. Due to many advantages of CCD cameras, astronomers began using them as the primary detector for photometry of stellar objects. A typical observatory, which operates one telescope at a time, obtained 0.5 TB of raw data during two decades, that means one million about 500 kB-sized files. There are several observatories in the Czech Republic and Slovakia (taking into account all scientific, public as well as private ones). A rough estimate of the total amount of this photometric data is 10 TB, which could be a very interesting source of observational data. Unfortunately, these data are not available online. These data are stored in observatory archives in arbitrary format. Often it is not even possible to find requested data. We have decided to change this state by establishing a common archive of raw photometric data, which would be available online together with tools for searching, listing etc. We already defined the data format, file and directory structure of our archive. We developed sophisticated tools for archive maintenance as well. Our goal is to provide data storage with simple and straightforward access and we are ready to interconnect with the VO right after the IVOA Photometry Data Model will be released.

Chrastina, Marek; Zejda, Miloslav; Mikulášek, Zden?k

2012-04-01

78

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.

2011-01-01

79

Regression by least median squares, a methodological contribution to titration analysis  

Microsoft Academic Search

Robust regression by least median squares, LMS, which is able to determine linear tendency provided that at least 50% of the experimental points comply with this tendency, has been applied to data from various titrations. The procedure based on the LMS regression provides an objective criterion for the determination of the end point; it can be reproduced and automated completely,

M. C. Ortiz-Fernández; A. Herrero-Gutiérrez

1995-01-01

80

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

2012-01-01

81

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

82

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

83

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

2011-01-01

84

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

PubMed

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 potentiometric titrations were carried out on the montmorillonite fractions extracted from two bentonites (MX80 and SWy2) to quantify their protolytic charge. The effects of equilibration time (24 h and 7 days), pH from 4 to 10, and ionic strength (0.1 and 0.01 mol L(-1)) were extensively studied for the MX80 sample. Quantification of dissolution was achieved by analysis of the equilibrium solutions for dissolved species and by La(3+) exchange of the readsorbed species. The results clearly show that secondary phases such as iron- or silica-rich minerals contribute to the dissolved species, according to the nature of the raw bentonite. Furthermore, readsorption affects significant amounts of dissolved species. The overconsumption of proton/hydroxide due to dissolution, readsorption, and hydrolysis of dissolved species was evaluated using a self-consistent thermodynamic calculation. The ability of such calculation to correct the raw titration curves in order to extract the titrable surface charge of montmorillonite was evaluated by comparison with the continuous titration procedure. Especially in the alkaline domain, correcting the raw batch titration curves for the measured side reactions failed to reproduce the continuous titration curves. These observations demonstrate the limitations of the batch titration method and the superiority of fast, continuous methods for quantifying the dissociable surface charge of clays. PMID:16777124

Duc, Myriam; Thomas, Fabien; Gaboriaud, Fabien

2006-08-15

85

An Olfactory Indicator for Acid-Base Titrations.  

ERIC Educational Resources Information Center

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

Flair, Mark N.; Setzer, William N.

1990-01-01

86

Potentiometric Titrations in a Poly(dimethylsiloxane)-Based Microfluidic Device  

E-print Network

Potentiometric Titrations in a Poly(dimethylsiloxane)-Based Microfluidic Device Rosaria Ferrigno device, fabricated in poly(dimethylsiloxane), that is used for potentiometric titrations. This system and characterize a microfluidic device that carries out potentiometric titrations and that uses serial dilution

Prentiss, Mara

87

Simple and Automated Coulometric Titration of Acid Using Nonisolated Electrodes  

ERIC Educational Resources Information Center

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

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

2011-01-01

88

Titration of dengue viruses by immunofluorescence in microtiter plates.  

PubMed Central

A fast, reliable, and inexpensive method was developed for titration of dengue viruses in microtiter plates with an indirect fluorescent-antibody technique. No significant differences were found in median infectious dose endpoints of samples titrated in microtiter plates as compared with titrations in multichambered slides. Images PMID:6392318

Schoepp, R J; Beaty, B J

1984-01-01

89

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.

1985-01-01

90

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 and calibrate a computational model­based titration algorithm for predictable laser dosimetry ranging from damage at different percentages of a reference titration energy dose. Experimental verification

Palanker, Daniel

91

Catalytic Methanol Oxidation Site Titration with Organic Bases During  

E-print Network

Catalytic Methanol Oxidation Site Titration with Organic Bases During Catalysis: Selectivity titration of protons with organic bases to control the densities of acid sites in Keggin clusters of Keggin structures was measured by titration of Brønsted acid sites with a sterically hindered pyridine (2

Iglesia, Enrique

92

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

2014-01-01

93

Photometric Properties of Vesta  

NASA Astrophysics Data System (ADS)

The Dawn spacecraft orbited Asteroid (4) Vesta for a year, and returned disk-resolved images and spectra covering visible and near-infrared wavelengths at scales as high as 20 m/pix. The visible geometric albedo of Vesta is ~ 0.36. The disk-integrated phase function of Vesta in the visible wavelengths derived from Dawn approach data, previous ground-based observations, and Rosetta OSIRIS observations is consistent with an IAU H-G phase law with H=3.2 mag and G=0.28. Hapke's modeling yields a disk-averaged single-scattering albedo of 0.50, an asymmetry factor of -0.25, and a roughness parameter of ~20 deg at 700 nm wavelength. Vesta's surface displays the largest albedo variations observed so far on asteroids, ranging from ~0.10 to ~0.76 in geometric albedo in the visible wavelengths. The phase function of Vesta displays obvious systematic variations with respect to wavelength, with steeper slopes within the 1- and 2-micron pyroxene bands, consistent with previous ground-based observations and laboratory measurement of HED meteorites showing deeper bands at higher phase angles. The relatively high albedo of Vesta suggests significant contribution of multiple scattering. The non-linear effect of multiple scattering and the possible systematic variations of phase function with albedo across the surface of Vesta may invalidate the traditional algorithm of applying photometric correction on airless planetary surfaces.

Li, Jian-Yang; Jorda, L.; Keller, H. U.; Mastrodemos, N.; Mottola, S.; Nathues, A.; Pieters, C.; Reddy, V.; Raymond, C. A.; Roatsch, T.; Russell, C. T.; Buratti, B. J.; Schroder, S. E.; Sykes, M. V.; Titus, T.; Capaccioni, F.; Capria, M. T.; Le Corre, L.; Denevi, B. W.; de Sanctis, M.; Hoffmann, M.; Hicks, M. D.

2015-03-01

94

Determination of sulphate by pH titration.  

PubMed

A simple and inexpensive method has been developed for the determination of sulphate and other very weak bases and acids. It utilizes the partial protonation of the weak base or the partial dissociation of the weak acid, which has not been exploited for analytical purposes thus far. The procedure consists of three pH titrations: one with a test solution of known sulphate content, the second with the sulphate sample, and the third with a blank. This method can be used in the presence of several inorganic ions and organic matrices, including non-aqueous solvents. In aqueous medium sulphate contents above 10(-3)M can be determined. The use of solvent mixtures may increase the sensitivity of the method by two orders of magnitude. PMID:18964322

Noszál, B; Juhász, M

1987-04-01

95

Astronomical Research Institute Photometric Results  

NASA Astrophysics Data System (ADS)

The Astronomical Research Institute (ARI) conducts astrometric and photometric studies of asteroids with a concentration on near-Earth objects (NEOs). A 0.76-m autoscope was used for photometric studies of seven asteroids of which two were main-belt targets and five were NEOs, including one potentially hazardous asteroid (PHA). These objects are: 3122 Florence, 3960 Chaliubieju, 5143 Heracles, (6455) 1992 HE, (36284) 2000 DM8, (62128) 2000 SO1, and 2010 LF86.

Linder, Tyler R.; Sampson, Ryan; Holmes, Robert

2013-01-01

96

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

97

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

98

Comparison of visual and photometric Bac-T-Screen results.  

PubMed

The Bac-T-Screen (Marion Laboratories, Kansas City, MO) was used to screen 826 urine specimens. Of these, 85 either pigmented or clogged the Bac-T-Screen filter and could not be evaluated. Results for the remaining 741 specimens were examined both visually and photometrically by a newly developed photometric card reader. The results were then compared. Screening results for all urines containing greater than or equal to 10(5) pathogens/mL were equivalent for both methods, with sensitivity and predictive negative values of greater than 98% and greater than 99%, respectively. The predictive values of positive tests were also equivalent at 57.5% for visual and 59.6% by photometry. The overall agreement varied with the card reader value used because the photometric card-reader procedure allows the user to select desired sensitivity and specificity levels. PMID:3518401

Wright, D N; Clark, S; Saxon, B; Matsen, J M

1986-05-01

99

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

1970-01-01

100

Micro-volume flow titration and screening the dissociation constants (p K a) of weak acids  

Microsoft Academic Search

A micro-volume, monosegmented flow analysis system has been developed for titration of weak acids and for determining dissociation constants (pKa) in the range 3–6, using pH indicators and spectroscopic detection. The system consists of a piston pump, a peristaltic pump, a detector and a 250?m i.d. reaction silica capillary. The analytical procedure for determining the acid concentration involves the sequential

Karin Carlsson; Bo Karlberg

2001-01-01

101

Bivoltametric titrations using electrodes with innovative geometry.  

PubMed

Electrodes with different surface areas were investigated for the determination of reversible, quasireversible, irreversible or electroinactive substrates. Two kinds of electrodes were constructed, a helical electrode with a given asymmetry and a platinum array electrode with a variable area. These electrodes were applied for the cerimetry of ammonium iron(II) sulfate and for the bromatometry of various organic substances. The theoretically derived effects on the shape of the voltametric titration curve are verified experimentally. It is possible to sharpen one side of the peak and to broaden the other side, depending on the system and the side of the peak one is interested in. It is possible to improve the bivoltametric determination of hydroquinone, benzocaine and sulfaguanidine by bromatometry by the directed employment of electrodes of different areas. For the bromatometric determination of electrochemically irreversible substrates the use of the electrode geometries proposed is a way to obtain a sharp bend and a steep decrease of titration curves with low values of the constant current which is a basic requirement for the accuracy. PMID:15048351

Surmann, P; Peter, B; Stark, C

1996-09-01

102

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.

2014-10-01

103

Potentiometric Titrations of Rutile Suspensions to 250°C  

Microsoft Academic Search

A stirred hydrogen electrode concentration cell was used to conduct potentiometric titrations of rutile suspensions from 25 to 250°C in NaCl and tetramethylammonium chloride media (0.03 to 1.1m). Hydrothermal pretreatment of the rutile improved titration reproducibility, decreased titration hysteresis, and facilitated determination of the point of zero net proton charge (pHznpc). These pHznpc values are 5.4, 5.1, 4.7, 4.4, 4.3

Michael L Machesky; David J Wesolowski; Donald A Palmer; Ken Ichiro-Hayashi

1998-01-01

104

A dipstick sensor for coulometric acid-base titrations  

Microsoft Academic Search

By performing an acid-base titration by coulometric generation of OH? or H+ ions at an inert electrode in close proximity to the pH-sensitive gate of an ISFET, it is possible to determine the acid or base concentration of a solution using the ISFET as an indicator device for the equivalence point in the titration curve. Typical values for the titration

W. Olthuis; Schoot van der B. H; F. Chavez; P. Bergveld

1989-01-01

105

Automated titration method for use on blended asphalts  

DOEpatents

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)

2012-08-07

106

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.

2003-12-01

107

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

ERIC Educational Resources Information Center

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

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

2014-01-01

108

Photometric Redshifts and Photometry Errors  

E-print Network

We examine the impact of non-Gaussian photometry errors on photometric redshift performance. We find that they greatly increase the scatter, but this can be mitigated to some extent by incorporating the correct noise model into the photometric redshift estimation process. However, the remaining scatter is still equivalent to that of a much shallower survey with Gaussian photometry errors. We also estimate the impact of non-Gaussian errors on the spectroscopic sample size required to verify the photometric redshift rms scatter to a given precision. Even with Gaussian {\\it photometry} errors, photometric redshift errors are sufficiently non-Gaussian to require an order of magnitude larger sample than simple Gaussian statistics would indicate. The requirements increase from this baseline if non-Gaussian photometry errors are included. Again the impact can be mitigated by incorporating the correct noise model, but only to the equivalent of a survey with much larger Gaussian photometry errors. However, these requirements may well be overestimates because they are based on a need to know the rms, which is particularly sensitive to tails. Other parametrizations of the distribution may require smaller samples.

D. Wittman; P. Riechers; V. E. Margoniner

2007-09-21

109

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.

1990-07-01

110

Photometric studies of the planet mercury  

Microsoft Academic Search

Mercury's surface brightness has been measured from 16 photographic plates representing an equal amount of different phases. The resulting photometric function turns out to be almost identical with the lunar photometric function.

K. A. Hämeen-Anttila; T. Pikkarainen; H. Camichel

1970-01-01

111

On the invention of conductimetric titration.  

PubMed

In contrast to the earlier statement of one of the authors according to which conductimetric titration was invented by Küster and Grüters in 1903, it is shown that Ostwald made use of this analytical method as early as the nineties of the past century. Prior to Ostwald's work, however, papers appeared in which conductimetric curves were shown, with statements about their different characteristics in the case of reaction between weak and strong acids and bases. The first of these seems to be due to Kohlrausch [together with one of his co-workers, Kreichgauer (1885)]. It does not seem to have occurred to them, however, to use this phenomenon for the purposes of analytical chemistry, namely for titrimetry. PMID:18963516

Szabadváry, F; Chalmers, R A

1983-12-01

112

Photometric Redshifts of Submillimeter Galaxies  

NASA Astrophysics Data System (ADS)

We use the photometric redshift method of Chakrabarti & McKee to infer photometric redshifts of submillimeter galaxies with far-IR (FIR) Herschel data obtained as part of the PACS Evolutionary Probe program. For the sample with spectroscopic redshifts, we demonstrate the validity of this method over a large range of redshifts (4 >~ z >~ 0.3) and luminosities, finding an average accuracy in (1 + z phot)/(1 + z spec) of 10%. Thus, this method is more accurate than other FIR photometric redshift methods. This method is different from typical FIR photometric methods in deriving redshifts from the light-to-gas mass (L/M) ratio of infrared-bright galaxies inferred from the FIR spectral energy distribution, rather than dust temperatures. To assess the dependence of our photometric redshift method on the data in this sample, we contrast the average accuracy of our method when we use PACS data, versus SPIRE data, versus both PACS and SPIRE data. We also discuss potential selection effects that may affect the Herschel sample. Once the redshift is derived, we can determine physical properties of infrared-bright galaxies, including the temperature variation within the dust envelope, luminosity, mass, and surface density. We use data from the GOODS-S field to calculate the star formation rate density (SFRD) of submillimeter bright sources detected by AzTEC and PACS. The AzTEC-PACS sources, which have a threshold 850 ?m flux >~ 5 mJy, contribute 15% of the SFRD from all ultraluminous infrared galaxies (L IR >~ 1012 L ?), and 3% of the total SFRD at z ~ 2.

Chakrabarti, Sukanya; Magnelli, Benjamin; McKee, Christopher F.; Lutz, Dieter; Berta, Stefano; Popesso, Paola; Pozzi, Francesca

2013-08-01

113

PHOTOMETRIC REDSHIFTS OF SUBMILLIMETER GALAXIES  

SciTech Connect

We use the photometric redshift method of Chakrabarti and McKee to infer photometric redshifts of submillimeter galaxies with far-IR (FIR) Herschel data obtained as part of the PACS Evolutionary Probe program. For the sample with spectroscopic redshifts, we demonstrate the validity of this method over a large range of redshifts (4 {approx}> z {approx}> 0.3) and luminosities, finding an average accuracy in (1 + z{sub phot})/(1 + z{sub spec}) of 10%. Thus, this method is more accurate than other FIR photometric redshift methods. This method is different from typical FIR photometric methods in deriving redshifts from the light-to-gas mass (L/M) ratio of infrared-bright galaxies inferred from the FIR spectral energy distribution, rather than dust temperatures. To assess the dependence of our photometric redshift method on the data in this sample, we contrast the average accuracy of our method when we use PACS data, versus SPIRE data, versus both PACS and SPIRE data. We also discuss potential selection effects that may affect the Herschel sample. Once the redshift is derived, we can determine physical properties of infrared-bright galaxies, including the temperature variation within the dust envelope, luminosity, mass, and surface density. We use data from the GOODS-S field to calculate the star formation rate density (SFRD) of submillimeter bright sources detected by AzTEC and PACS. The AzTEC-PACS sources, which have a threshold 850 {mu}m flux {approx}> 5 mJy, contribute 15% of the SFRD from all ultraluminous infrared galaxies (L{sub IR} {approx}> 10{sup 12} L{sub Sun }), and 3% of the total SFRD at z {approx} 2.

Chakrabarti, Sukanya [School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Magnelli, Benjamin; Lutz, Dieter; Berta, Stefano; Popesso, Paola [Max-Planck-Institut fuer Extraterrestrische Physik, Postfach 1312, Giessenbachstrasse 1, D-85741 Garching (Germany); McKee, Christopher F. [Physics and Astronomy Departments, UC Berkeley, Berkeley, CA 94720 (United States); Pozzi, Francesca, E-mail: chakrabarti@astro.rit.edu [Dipartimento di Astronomia, Universita degli Studi di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)

2013-08-20

114

Infrared titration of aqueous sulfuric acid  

SciTech Connect

This paper presents the infrared (IR) titration of aqueous sulfuric acid solutions (0.50 M) obtained by the attenuated total reflection (ATR) sampling technique. After subtracting the water spectra, the spectra of the ionic species of H{sub 2}SO{sub 4} in the 0--14 pH range were separated by factor analysis (FA) which also gave their abundance. The results were in agreement with the theoretical calculation of the distribution of the species. Three sulfate species were found: HSO{sub 4}{sup {minus}}, SO{sub 4}{sup 2{minus}}, and HSO{sub 4}{sup {minus}}/HCl. The latter stands for the bisulfate--hydronium complex formed by the addition of HCl to obtain measurements in the 0--0.47 pH range. For 0.50 M sulfuric acid, the comparison between the experimentally IR-determined quantities and the theoretical values gave a mean activity coefficient of 0.12 {+-} 0.04, a value comparable to that from electrochemical measurements. Three types of water were quantitatively determined in the solutions: acidic water, basic water, and neutral water. The latter is always present while the two others are present in the low and high pH range, respectively. Another type of water strongly associated with the sulfates is also present. Moreover, knowledge of the behavior of the different types of water as the titration proceeded permitted us to give the details of the neutralization reactions of aqueous sulfuric acid by sodium hydroxide.

Max, J.J.; Menichelli, C.; Chapados, C.

2000-03-30

115

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)

1994-12-01

116

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

PubMed

The methodology of continuous feedback-based flow titrations and the principle of compensating errors [Anal. Chem. 72 (2000) 4713; Anal. Chim. Acta 435 (2001) 289] were applied to the determination of calcium and magnesium ions with EDTA. The flow of the titrant, EDTA, varied linearly in response to a controller output voltage while the total flow (F(T), the sum of the metal ion sample flow and the titrant flow) was held constant. The sample was pre-doped with a metal ion indicator; the status of the indicator color in the mixed stream was monitored by an optical detector and was used for governing the controller output as well as for interpreting the results of the titrations. The titrant flow initially ramped upward linearly. As a change in the color corresponding to the equivalence point was sensed by the detector, the controller output (instantaneous value V(H)) reversed its ramp direction, thus decreasing the titrant flow linearly at the same ramp rate. When the predefined absorbance corresponding to the equivalence point was sensed again, the controller voltage (instantaneous value V(L)) was ramped in reverse once more, going upward. Because of the lag time between a change in the controller output and its effect being sensed by the detector, the controller voltage corresponding to the actual equivalence point was the average of V(H) and V(L). Continuous sensor-governed operation of the controller resulted in a triangular waveform. The mean of this waveform during any cycle gives the equivalence point controller voltage V(E). This principle allowed true titrations with good reproducibility (0.2-0.7% R.S.D.) and throughput (33-42 s per titration). PMID:18969033

Jo, Kyoo Dong; Dasgupta, Purnendu K

2003-05-28

117

LABORATORY EXPERIMENT 4 Alkalimetric Titration of an Acid Mixture  

E-print Network

to semi-automatic volumetric analysis and potentiometric titrations. Phosphoric Acid, H3PO4 (pK1= 2.16, pLABORATORY EXPERIMENT 4 Alkalimetric Titration of an Acid Mixture In this experiment triprotic acid (H3PO4) will be determined by pH- potentiometric methods. This experiment will introduce you

Nazarenko, Alexander

118

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

2008-01-01

119

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

2005-01-01

120

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

1981-01-01

121

Students' integration of multiple representations in a titration experiment  

NASA Astrophysics Data System (ADS)

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

Kunze, Nicole M.

122

SIMULTANEOUS TITRIMETRIC DETERMINATION OF BICARBONATE AND TITRATABLE ACID OF URINE  

Microsoft Academic Search

An acid-titration method for the determination of bicarbonate and titratable acid in the one sample of urine is described. The method needs only one manipulation of the sample of urine, and was devised to simplify routine laboratory methodology. The accuracy and precision of the urinary bicarbonate method during routine laboratory use is comparable to that obtained by using the Van

AZ Györy; KDG Edwards

1967-01-01

123

Continuous on-line true titrations by feedback based flow ratiometry: application to potentiometric acid–base titrations  

Microsoft Academic Search

We applied the methodology of continuous titrations by feedback-based flow ratiometry and the principle of compensating errors [Anal. Chem. 72 (2000), 4713] to potentiometric acid–base titrations. In a typical case, the titrant (a standard base) flow (FB) is varied in response to a controller output voltage, while the total flow (FT, consisting of an acid sample and the titrant flow)

Purnendu K Dasgupta; Hideji Tanaka; Kyoo Dong Jo

2001-01-01

124

Photometric Variability of Y Dwarfs  

NASA Astrophysics Data System (ADS)

Condensate clouds are present in brown dwarf atmospheres due to their low surface temperatures. As the coolest (Teff < 600 K) class of brown dwarfs currently known, Y dwarfs allow us to study the unique atmospheric physics that occur at these temperatures including the formation of sulfide, chloride, and water clouds. Dynamic inhomogeneities in cloud cover should manifest as photometric variabilities in the observed light curves of brown dwarfs. This phenomenon was originally documented in two brown-dwarfs by Morales-Calderón et al. (2006) at 4.5 microns, and in one brown dwarf by Heinze et al. (2013) at 3.6 microns. We describe our ongoing program to monitor fourteen Y dwarfs for photometric variability at 3.6 and 4.5 microns with the Spitzer Space Telescope and present initial results including the first detection of Y dwarf variability.

Trucks, Jesica; Cushing, M.; Hardegree-Ullman, K.; Gelino, C. R.; Kirkpatrick, J. D.; Mace, G. N.; Gizis, J.; Marley, M. S.; Morley, C.; Fortney, J. J.

2014-01-01

125

Toward Millimagnitude Photometric Calibration (Abstract)  

NASA Astrophysics Data System (ADS)

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

Dose, E.

2014-12-01

126

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.)

1990-07-01

127

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

2003-01-01

128

BPZ: Bayesian Photometric Redshift Code  

NASA Astrophysics Data System (ADS)

Photometric redshift estimation is becoming an increasingly important technique, although the currently existing methods present several shortcomings which hinder their application. Most of those drawbacks are efficiently eliminated when Bayesian probability is consistently applied to this problem. The use of prior probabilities and Bayesian marginalization allows the inclusion of valuable information, e.g. the redshift distributions or the galaxy type mix, which is often ignored by other methods. In those cases when the a priori information is insufficient, it is shown how to `calibrate' the prior distributions, using even the data under consideration. There is an excellent agreement between the 108 HDF spectroscopic redshifts and the predictions of the method, with a rms error Delta z/(1+z_spec) = 0.08 up to z<6 and no systematic biases nor outliers. The results obtained are more reliable than those of standard techniques even when the latter include near-IR colors. The Bayesian formalism developed here can be generalized to deal with a wide range of problems which make use of photometric redshifts, e.g. the estimation of individual galaxy characteristics as the metallicity, dust content, etc., or the study of galaxy evolution and the cosmological parameters from large multicolor surveys. Finally, using Bayesian probability it is possible to develop an integrated statistical method for cluster mass reconstruction which simultaneously considers the information provided by gravitational lensing and photometric redshifts.

Benítez, Narciso

2011-08-01

129

Studies on the acidity of mordenite and ZSM-5. 1. Determination of Broensted acid site concentrations in mordenite and ZSM-5 by conductometric titration  

SciTech Connect

The Broensted acidity of H-mordenite and H-ZSM-5 samples of varying proton concentration has been studied using aqueous conductometric titration, IR spectroscopy, and aqueous potentiometric titration. Good agreement is observed between Broensted acid site concentrations determined by conductometric titration and IR measurements, while indirect potentiometric titration affords acid site concentrations consistently lower than those measured using the conductometric technique. This finding is rationalized on the basis that, in a conductometric titration, all the accessible Broensted acid sites are direct;y titrated, whereas in the potentiometric procedure utilized, only those protons which can be ion-exchanged out of the zeolite are titrated. After allowing for the presence of extraframework aluminum in the zeolites (determined by [sup 27]Al NMR), the measured acidity for H-mordenite is found to increase linearly with increasing Al content within the range 0-1.5 mmol Al/g but appears to reach a limiting value at higher Al concentrations. For H-ZSM-5, the experimentally determined number of Broensted acid sites is also found to be linearly dependent on the Al molar fraction within the range measured (0-1.20 mmol Al/g). For both series of zeolite samples, the measured acidity is generally found to be less than the theoretical maximum calculated on the basis of an H[sup +]/Al ratio of 1. 43 refs., 10 figs., 4 tabs.

Crocker, M.; Herold, R.H.M.; Sonnemans, M.H.W.; Emeis, C.A.; Wilson, A.E.; Moolen, J.N. van der (Koninklijke/Shell-Laboratorium, Amsterdam (Netherlands))

1993-01-14

130

Novel titration method for surface-functionalised silica  

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

131

Calibrating Photometric Redshifts of Luminous Red Galaxies  

E-print Network

We discuss the construction of a photometric redshift catalogue of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS), emphasizing the principal steps necessary for constructing such a catalogue -- (i) photometrically selecting the sample, (ii) measuring photometric redshifts and their error distributions, (iii) and estimating the true redshift distribution. We compare two photometric redshift algorithms for these data and find that they give comparable results. Calibrating against the SDSS and SDSS-2dF spectroscopic surveys, we find that the photometric redshift accuracy is $\\sigma \\sim 0.03$ for redshifts less than 0.55 and worsens at higher redshift ($\\sim 0.06$). These errors are caused by photometric scatter, as well as systematic errors in the templates, filter curves, and photometric zeropoints. We also parametrize the photometric redshift error distribution with a sum of Gaussians, and use this model to deconvolve the errors from the measured photometric redshift distribution to estimate the true redshift distribution. We pay special attention to the stability of this deconvolution, regularizing the method with a prior on the smoothness of the true redshift distribution. The methods we develop are applicable to general photometric redshift surveys.

Nikhil Padmanabhan; Tamas Budavari; David J. Schlegel; Terry Bridges; Jonathan Brinkmann; Russell Cannon; Andrew J. Connolly; Scott M. Croom; Istvan Csabai; Michael Drinkwater; Daniel J. Eisenstein; Paul C. Hewett; Jon Loveday; Robert C. Nichol; Kevin A. Pimbblet; Roberto De Propris; Donald P. Schneider; Ryan Scranton; Uros Seljak; Tom Shanks; Istvan Szapudi; Alexander S. Szalay; David Wake

2005-05-24

132

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

Buschmann, Michael

133

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

PubMed

In the present paper, the utility of a special potentiometric titration approach for recognition and calculation of biomolecule/small-molecule interactions is reported. This approach is fast, sensitive, reproducible, and inexpensive in comparison to the other methods for the determination of the association constant values (Ka) and the interaction energies (?G). The potentiometric titration measurement is based on the use of a classical polymeric membrane indicator electrode in a solution of the small-molecule ligand. The biomolecule is used as a titrant. The potential is measured versus a reference electrode and transformed into a concentration-related signal over the entire concentration interval, also at low concentrations, where the millivolt (y-axis) versus log canalyte (x-axis) potentiometric calibration curve is not linear. In the procedure, Ka is calculated for the interaction of cocaine with a cocaine binding aptamer and with an anticocaine antibody. To study the selectivity and cross-reactivity, other oligonucleotides and aptamers are tested, as well as other small ligand molecules such as tetrakis(4-chlorophenyl)borate, metergoline, lidocaine, and bromhexine. The calculated Ka compared favorably to the value reported in the literature using surface plasmon resonance. The potentiometric titration approach called "concentration-related response potentiometry" is used to study molecular interaction for seven macromolecular target molecules and four small-molecule ligands. PMID:25390494

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

2014-12-16

134

A photometric study of Enceladus  

NASA Technical Reports Server (NTRS)

We have supplemented Voyager imaging data from Enceladus (limited to phase angles of 13 deg-43 deg) with recent Earth-based CCD observations to obtain an improved determination of the Bond albedo, to construct an albedo map of the satellite, and to constrain parameters in Hapke's (1986) photometric equation. A major result is evidence of regional variations in the physical properties of Enceladus' surface. The average global photometric properties are described by single scattering albedo omega(sub 0) average = 0.998 +/- 0.001, macroscopic roughness parameter theta average = 6 +/- 1 deg, and Henyey-Greenstein asymmetry parameter g = -0.399 +/- 0.005. The value of theta average is smaller than the 14 deg found by fitting whole-disk data, which include all terrains on Enceladus. The opposition surge amplitude B(sub 0) = 0.21 +/- 0.07 and regolith compaction parameter h = 0.014 +/- 0.02 are loosely constrained by the scarcity of and uncertainty in near-opposition observations. From the solar phase curve we determine the geometric albedo of Enceladus p(sub v) = 0.99 +/- 0.06 and phase integral q = 0.92 +/- 0.05, which corresponds to a spherical albedo A = p(sub v)q = 0.91 +/- 0.1. Since the spectrum of Enceladus is fairly flat, we can approximate the Bond albedo A(sub B) with the spherical albedo. Our photometric analysis is summarized in terms of an albedo map which generally reproduces the satellite's observed lightcurve and indicates that normal reflectances range from 0.9 on the leading hemisphere to 1.4 on the trailing one. The albedo map also revels an albedo variation of 15% from longitudes 170 deg to 200 deg, corresponding to the boundary between the leading and trailing hemispheres.

Verbiscer, Anne J.; Veverka, Joseph

1994-01-01

135

Cosmology with photometric redshift surveys  

E-print Network

We explore the utility of future photometric redshift imaging surveys for delineating the large-scale structure of the Universe, and assess the resulting constraints on the cosmological model. We perform two complementary types of analysis: (1) We quantify the statistical confidence and the accuracy with which such surveys will be able to detect and measure characteristic features in the clustering power spectrum such as the acoustic oscillations and the turnover, in a 'model-independent' fashion. We show for example that a 10,000 deg^2 imaging survey with depth r = 22.5 and photometric redshift accuracy dz/(1+z) = 0.03 will detect the acoustic oscillations with 99.9% confidence, measuring the associated preferred cosmological scale with 2% precision. Such a survey will also detect the turnover with 95% confidence, determining the corresponding scale with 20% accuracy. (2) By assuming a Lambda-CDM model power spectrum we calculate the confidence with which a non-zero baryon fraction can be deduced from such future galaxy surveys. We quantify 'wiggle detection' by calculating the number of standard deviations by which the baryon fraction is measured, after marginalizing over the shape parameter. This is typically a factor of four more significant (in terms of number of standard deviations) than the 'model-independent' result. We conclude that the precision with which the clustering pattern may be inferred from future photometric redshift surveys will be competitive with contemporaneous spectroscopic redshift surveys, assuming that systematic effects can be controlled. We also note that an analysis of Luminous Red Galaxies in the Sloan Digital Sky Survey may yield a marginal detection of acoustic oscillations in the imaging survey, in addition to that recently reported for the spectroscopic component.

Chris Blake; Sarah Bridle

2005-08-19

136

Photometric commissioning results from MINERVA  

NASA Astrophysics Data System (ADS)

MINERVA is a robotic observatory with four 0.7 meter telescopes at Mt. Hopkins, Arizona, dedicated to precise photometry and radial velocity observations of bright, nearby stars for the discovery and characterization of small exoplanets. Here we present the first photometric results from MINERVA during commissioning at our test facility in Pasadena, California, demonstrating sub-millimag precision on 3-5 minute timescales over several hours. These results show that MINERVA is well-equipped to address its secondary science goal of searching for transits of known and newly discovered super-Earth exoplanets detected by radial velocity, including potential detections from the MINERVA spectrograph.

Eastman, Jason D.; Swift, Jonathan; Beatty, Thomas G.; Bottom, Michael; Johnson, John; Wright, Jason; McCrady, Nate; Wittenmyer, Robert A.; Riddle, Reed L.; Plavchan, Peter; Muirhead, Philip Steven; Blake, Cullen; Zhao, Ming

2015-01-01

137

Atmospheric emissions photometric imaging experiment  

NASA Technical Reports Server (NTRS)

The atmospheric emissions photometric imaging experiment was flown on Spacelab 1 to study faint natural and artificial atmospheric emission phenomena. The instrument imaged optical emission in the region 2000 to 7500 angstroms with a television system consisting of two optical channels, one wide-angle and one telephoto. A third optical channel imaged onto the photocathode of a microchannel plate photomultiplier tube that has 100 discrete anodes. A hand-held image intensifier camera with an objective grating permitted spectral analysis of the earth's airglow and the Shuttle glow. Preliminary data show magnesium ion emission features in the lower ionosphere as well as the spacecraft glow spectrum.

Mende, S. B.; Swenson, G. R.; Clifton, K. S.

1984-01-01

138

Photometric System Design and Performances  

NASA Astrophysics Data System (ADS)

If unsupported by appropriate diagnostic data, Gaia would yield immense numbers of positions and velocities of objects whose astrophysical nature would be unknown. The core science case requires measurement of luminosity, effective temperature, mass, age and chemical composition for the stellar populations in the Galaxy and its nearest neighbours. These quantities can be derived from the spectral energy distribution of the stars, i.e. through high-quality multi-band photometry. The current proposals for broad and medium band photometric systems, their capabilities for the astrophysical parametrization of the stars and hence the expected precision of the stellar populations characterization are reviewed.

Jordi, C.; Høg, E.

2005-01-01

139

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

1993-01-01

140

Titration Microcalorimetry Study: Interaction of Drug and Ionic Microgel System  

E-print Network

Doxorubicin (DOX) and Pluronic-PAA interaction was investigated using isothermal titration calorimetry (ITC). DOX/polymer interaction is governed primarily by electrostatic interaction. The uptake of DOX results in the ...

Tian, Y.

141

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

1998-01-15

142

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

2012-06-29

143

APIRP: The Automated Photometric Data Reduction Package  

NASA Astrophysics Data System (ADS)

For decades the Image Reduction and Analysis Facility (IRAF) has been the standard for processing CCD-based image datasets. During that time, technology has advanced and the astronomical record greatly expanded. However, the discovery process is often bogged down by the time consuming procedures of image reduction. To keep up with demand and shorten reduction steps programmers have developed a series of command languages (CL) for IRAF and most recently, within only the past five years, the Python-based language, Pyraf. Python is a robust and powerful language that combines syntactical simplicity with versatile and dynamic file management, database access and software development capabilities, to name just a few features. Pyraf, by extension, incorporates all of the qualities of IRAF CL, with all of the power and flexibility provided by Python. Pyraf scripts may be written to automate file processing at the same time that reduction tasks are called from IRAF. Thus, the potential to write fully automated reduction procedures is here; tightening the gaps of scientific advancement. We have created such a tool for CCD Photometry. Our Automated Photometric Image Reduction Package (APIRP) uses a range of graphical user interfaces (GUI's) to form an interactive yet non-overbearing user environment. A combination of built-in file management and procedural variability makes APIRP a perfect choice for both amateur and professional astronomers. Due to the programs design, it can be run from anywhere on your computer and users can specify exactly what steps of reduction they wish to execute. Thus, setup is easy with no need for cumbersome documentation and tasks may be preformed piecewise or in blocks, depending on the users needs.

Hebert, Ian; Ziffer, J.; Walker, M.

2009-09-01

144

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.

1976-01-01

145

Last Photometrics Data from Oukaimeden  

NASA Astrophysics Data System (ADS)

The University of Marrakech is helping the formation of a young team of researchers in astronomy. The short term goal of this group is acquiring theoretical and experimental skills in various astrophysical fields but mainly centred on site testing, because the long term goal is the construction of a New National Moroccan Observatory to be installed at mount Oukaomeden. Actually, since 1998, our group began an astronomical site evaluation from the point of view of day photometry, ground climatology and turbulence modelling. In 1988, as soon as Oukaimeden site was selected, we planned to conduct a photometric study of the site. By this time the Global Oscillation Network Group (GONG) installed a peryheliometer (Fischer, 1986) to achieve a complementary photometric study of the sunlight. We present in this contribution some last results of clouds cover, extinction coefficient and transparency fluctuations measurement of the site, using a total solar intensity provided by IRIS helioseismograph, located at Oukaimeden. We used the same methods made by Hill et al. (1994) in the GONG site testing campaign and Benkhaldoun et al. (1993) using a simple flux integration photometer.

Benkhaldoun, Z.; Siher, E.

146

Photometric Science Alerts from Gaia  

NASA Astrophysics Data System (ADS)

Gaia is a European Space Agency (ESA) astrometry space mission, and a successor to the ESA Hipparcos mission. The main goal of the Gaia mission is to collect high- precision astrometric data (i.e. positions, parallaxes, and proper motions) for the brightest one billion objects in the sky. This data, complemented with G band, multi-epoch photometric and low resolution (lowers) spectroscopic data collected from the same observing platform, will allow astronomers to reconstruct the formation history, structure, and evolution of the Galaxy. In addition, the Gaia satellite is an excellent transient discovery instrument, cov- ering the whole sky (including the Galactic plane) for the next 5 years, at high spatial resolution (50 to 100 mas, similar to the Hubble space telescope (HST)) with precise photometry (1% at G=19) and milliarcsecond astrometry (down to ˜20mag). Thus, Gaia provides a unique opportunity for the discovery of large numbers of transient and anomalous events, e.g. supernovae, black hole binaries and tidal disruption events. We discuss the validation of the alerts stream for the first six months of the Gaia observations, in particular noting how a significant ground based campaign involving photometric and spectroscopic followup of early Gaia alerts is now in place. We discuss the validation approach, and highlight in more detail the specific case of Type Ia supernova (SNe Ia) to be discovered by Gaia. The intense initial ground based validation campaign will ensure that the Gaia alerts stream for the remainder of the Gaia mission, are well classified.

Campbell, H.; Blagorodnova, N.; Fraser, M.; Gilmore, G.; Hodgkin, S.; Koposov, S.; Walton, N.; Wyrzykowski, L.

147

Reliable pKw values from potentiometric titrations: the striking effect of the titration final added volume.  

PubMed

Errors affecting the estimation of the ionic product of water from the potentiometric titration of weak acids have been analysed. A Fortran programme has been developed in order to simulate experimental titration data sets. This programme allows one to isolate experimental error sources and analyse their effect upon the final fitted equilibrium constant. pKw dependence with titration final added volume and the pK value of the weak acid, predicted with the simulation programme are coincident with experimental data, suggesting that obtaining reliable pKw values entails using experimental data of titrations up to a sufficiently large hydroxyl concentration which depends on the value of pK. PMID:11770160

Brandariz, I; Vilariño, T; Barriada, J L; Sastre De Vicente, M E

2001-01-01

148

POTENTIOMETRIC TITRATION OF AN ACID MIXTURE Background Reading: Harris, 7th  

E-print Network

POTENTIOMETRIC TITRATION OF AN ACID MIXTURE Background Reading: Harris, 7th ed., Chapter 11. Skoog equivalence point to permit estimation with visual indicators, a potentiometric titration with a pH meter added. The titration may be terminated at pH 11. #12;Potentiometric Titration of an Acid Mixture, Page 2

McQuade, D. Tyler

149

Computer-processed potentiometric titration for the determination of calcium and magnesium in sea water  

Microsoft Academic Search

An improved potentiometric titration method for the determination of calcium and magnesium in sea water has been newly devised. In this method, a mini-computer is used for the automation of titrations, and ion-selective electrodes are used as an end-point detector. Calcium is determined by titration with EGTA, and total alkaline earth metals (magnesium + calcium + strontium) by titration with

Satoru Kanamori; Hisashi Ikegami

1980-01-01

150

Titration Force Microscopy on Supported Lipid Sergi Garcia-Manyes, Pau Gorostiza, and Fausto Sanz*,  

E-print Network

Titration Force Microscopy on Supported Lipid Bilayers Sergi Garcia-Manyes, Pau Gorostiza titration where the titration agent is a weak acid (attached to the AFM tip) with the particularity of being to the pKa of the surface under study and the other to the pKa of the titrating probe attached to the tip

Fernandez, Julio M.

151

Photometric metallicities in Boötes I  

NASA Astrophysics Data System (ADS)

We present new Strömgren and Washington data sets for the Boötes I dwarf galaxy, and combine them with the available Sloan Digital Sky Survey photometry. The goal of this project is to refine a ground-based, practical, accurate method to determine age and metallicity for individual stars in Boötes I that can be selected in an unbiased imaging survey, without having to take spectra. With few bright upper red giant branch stars and distances of about 35-250 kpc, the ultra-faint dwarf galaxies (UDFs) present observational challenges in characterizing their stellar population. Other recent studies have produced spectra and proper motions, making Boötes I an ideal test case for our photometric methods. We produce photometric metallicities from Strömgren and Washington photometry, for stellar systems with a range of -1.0 > [Fe/H] > -3.5. Needing to avoid the collapse of the metallicity sensitivity of the Strömgren m1-index on the lower red giant branch, we replace the Strömgren v filter with the broader Washington C filter to minimize observing time. We construct two indices: m* = (C - T1)0 - (T1 - T2)0 and m** = (C - b)0 - (b - y)0. We find that CT1by is the most successful filter combination, for individual stars with [Fe/H] < -2.0, to maintain ˜0.2 dex [Fe/H]-resolution over the whole red giant branch. The m**-index would be the best choice for space-based observations because the (C - y) colour is not sufficient to fix metallicity alone in an understudied system. Our photometric metallicites of stars in the central regions of Boötes I confirm that there is a metallicity spread of at least -1.9 > [Fe/H] > -3.7. The best-fitting Dartmouth isochrones give a mean age, for all the Boötes I stars in our data set, of 11.5 ± 0.4 Gyr. From ground-based telescopes, we show that the optimal filter combination is CT1by, avoiding the v filter entirely. We demonstrate that we can break the isochrones' age-metallicity degeneracy with the CT1by filters, using stars with log g = 2.5 - 3.0, which have less than a 2 per cent change in their (C - T1) colour due to age, over a range of 10-14 Gyr.

Hughes, J.; Wallerstein, G.; Dotter, A.; Geisler, D.

2014-03-01

152

Standard Photometric Systems Michael S. Bessell  

E-print Network

1 Standard Photometric Systems Michael S. Bessell Research School of Astronomy and Astrophysics: photometric,spectroscopic catalogs. ABSTRACT: Standard star photometry dominated the second part of the 20th of photodetectors improved and the wavelength range extended further to the red, standard systems were modi ed

Harrison, Thomas

153

The calibration of photometric determinations of abundance  

NASA Astrophysics Data System (ADS)

Photometric abundance determination using blanketing in the ultraviolet and violet spectral regions as well as the intensity of strong lines and bands is pointed to as the most important tool in the study of chemical composition of faint and distant stars. This method, however, requires the calibration of different photometric quantities in terms of abundance at different temperatures and luminosities. Two principals of calibration are in use. One uses stars with abundances determined from high dispersion spectra by curve of growth or model atmosphere analysis of the spectral lines. The other uses synthetic spectra based on model atmospheres which are integrated to imitate the narrow band photometric indices. The results of the application of both of these methods to calibrate a number of the important photometric systems are summarized. Attention is given to the late-type stars which demonstrate the strongest photometric abundance effects.

Straizys, V.

154

Analysis of acid-soluble chloride in cement, mortar, and concrete by potentiometric titration without filtration steps  

Microsoft Academic Search

A potentiometric titration procedure that makes use of Gran’s method for end-point detection has been developed to analyze acid-soluble chloride in cement, mortar, and concrete, eliminating the filtration steps performed in habitual laboratory reference methods. The accuracy and reliability of the proposed analytical technique has been checked against a standard method, such as Volhard’s, by analyzing duplicate samples of cements,

Miguel A. Climent; Estanislao Viqueira; Guillem de Vera; M. M. López-Atalaya

1999-01-01

155

Ring-light Photometric Stereo Zhenglong Zhou Ping Tan  

E-print Network

­11] studying this problem without recording illumination conditions, known as uncalibrated photometric stereo to study uncalibrated photometric stereo by exploiting constrains in lighting configurations such that ourRing-light Photometric Stereo Zhenglong Zhou Ping Tan Department of Electrical & Computer

Tan, Ping

156

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.

1960-01-01

157

Photometric Observation and Apsidal motion Study of V1143 Cyg  

E-print Network

Photometric observations of the eccentric eclipsing binary V1143 Cygni were performed during the August-September 2000 and July 2002, in B and V bands of the Johnson system. The analysis on both light curves was done separately using the 1998 version of Wilson's LC code. In order to find a new observed rate of apsidal motion, we followed the procedure described by Guinan and Maloney (1985). A new observed rate of apsidal motion of 3.72 degrees/100yr was computed which is close to the one reported earlier by Khaliullin (1983), Gimenez and Margrave (1985), and Burns et al.(1996).

A. Dariush; N. Riazi; A. Afroozeh

2004-11-30

158

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

1994-01-01

159

Determination of liposome partitioning of ionizable drugs by titration.  

PubMed

Drug partitioning to liposomes has been suggested as a model for partitioning to biomembranes but has been lacking a rapid analytical assay useful for drug screening. A fast pH-metric titration method for the determination of liposome partitioning of ionizable drugs using small unilamellar phosphatidylcholine vesicles prepared by sonic homogenization has been successfully developed, enabling the use of high lipid-to-drug ratios. Liposome-water partition coefficients of diclofenac and propranolol were determined to study the impact of varying titration parameters, temperature, equilibration time, lipid, and liposome types on the partitioning. To validate this method, the results were compared to literature values generated with different techniques and to pH-metric titration results with large unilamellar vesicles. The rapid pH-metric assay gave liposome partitioning data for the two model compounds which were consistent with other analytical techniques and liposome types. PMID:10430546

Balon, K; Riebesehl, B U; Müller, B W

1999-08-01

160

Photometric Studies of GEO Debris  

NASA Astrophysics Data System (ADS)

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 Michigans 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? 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. We will compare our observations with models and laboratory measurements of selected surfaces. This work is supported by NASAs Orbital Debris Program Office, Johnson Space Center, and Houston, Texas, USA.

Seitzer, P.; Rodriguez-Cowardin, H.; Barker, E.; Abercromby, K.; Foreman, G.; Horstman M.

161

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

2009-01-01

162

Constant-Current Coulometric Titration of Hydrochloric Acid  

NASA Astrophysics Data System (ADS)

The titration of a strong acid with a strong base and the electrolysis of water are two classic laboratory exercises that are either performed or demonstrated in secondary school classrooms in order to introduce two important areas of chemsitry: acid-base chemistry and electrochemistry. In this experiment we have combined these two classical experiments into one complete laboratory experience. Here we report how the elctrolysis of an aqueous solution can be used to determine the concentration of hydrochloric acid in a coulometric titration.

Swim, James; Earps, Edward; Reed, Laura M.; Paul, David

1996-07-01

163

OZONE CALIBRATION AND AUDIT BY GAS PHASE TITRATION IN EXCESS OZONE. BENDIX (TRADE NAME) TRANSPORTABLE FIELD CALIBRATION SYSTEM, MODELS 8861D AND 8861DA  

EPA Science Inventory

Detailed procedures for the dynamic calibration and audit of chemiluminescence ozone analyzers are presented. The calibrations and audits are performed by means of a gas phase titration technique using the rapid gas phase reaction between nitric oxide and ozone with excess ozone ...

164

Photometric Study of Uranian Satellites  

NASA Astrophysics Data System (ADS)

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.

1998-10-01

165

Photometric properties of Triton hazes  

NASA Technical Reports Server (NTRS)

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

Hillier, J.; Veverka, J.

1994-01-01

166

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.

1998-01-01

167

LABORATORY EXPERIMENT 3 Alkalimetric Titration of an Acid  

E-print Network

LABORATORY EXPERIMENT 3 Alkalimetric Titration of an Acid A carbonate-free sodium hydroxide goal is to prepare a carbonate-free sodium hydroxide solution and standardize it. Sodium hydroxide solution is prepared and standardized. Preparation and standardization of sodium hydroxide solution. Our

Nazarenko, Alexander

168

Potentiometric titration of gold, platinum, and some other precious metals  

SciTech Connect

Gold, platinum, and several other platinum metals can be determined by titration with cetylpyridinium chloride (CPC). CPC forms a precipitate with AuCl{sub 4}{sup {minus}} and PtCl{sub 6}{sup 2{minus}}. Differentiation of AuCl{sub 4{minus}} and PtCl{sub 6}{sup 2{minus}} with this titrant is not possible; however, their sum can be determined. Titration with tetraphenylarsonium chloride at pH 1 is selective for tetrachloroaurate, which thus can be determined in the presence of hexachloroplatinate. Hexachloroosmate(IV), tetrachloroplatinite(II), tetrachloropalladate(II), hexachloropalladate(IV), and hexachloroiridate(IV) can also be determined potentiometrically vs. CPC. The indicating electrode is prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) (PVC) and dioctylphthalate (DOP) in tetrahydrofuran (THF). Gold in gold cyanide plating baths and in potassium aurocyanide can be determined by potentiometric titration vs standard silver nitrate, using a silver ion-selective indicating electrode. The monovalent gold need not be converted to the trivalent state with aqua regia, resulting in a considerable saving of time and effort. Free cyanide and aurocyanide can be titrated sequentially by this method. Chloride does not interfere and can, in fact, also be sequentially determined. 17 refs., 2 figs., 3 tabs.

Selig, W.S.

1991-02-04

169

Surface properties of red mud particles from potentiometric titration  

Microsoft Academic Search

Acid\\/basic potentiometric titration has been used to obtain data on the surface charge and the amount of surface hydroxyl groups on red mud particles generated from different bauxite sources. It has been demonstrated that this can be used to quantify the surface properties of red mud particles. Red mud particles carry a significant negative charge under the basic conditions that

D Chvedov; S Ostap; T Le

2001-01-01

170

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

171

Acid Base Titrations in Nonaqueous Solvents and Solvent Mixtures  

Microsoft Academic Search

The acid base determination of different substances by nonaqueous titrations is highly preferred in pharmaceutical analyses since the method is quantitative, exact, and reproducible. The modern interpretation of the reactions in nonaqueous solvents started in the last century, but several inconsistencies and unsolved problems can be found in the literature. The acid base theories of Brønsted Lowry and Lewis as

Lajos Barcza; Ágnes Buvári-Barcza

2003-01-01

172

Titration of Isolated Cell Walls of Lemna minor L.  

PubMed

A theoretical model has been built to bypass the equation of titration of the cell wall. This equation, which is an extension of the Henderson-Hasselbach equation, underlines the importance of the exchange constant, the ionic strength as well as the rate of neutralization. The model is restricted to the case when the ionization degree is equal to the neutralization degree. The shape of the titration curve is shown to be strongly dependent on the valency of the base used.Experimental results have shown that isolated cell walls bear at least two kinds of sites. The first sites which are titrated after a short time of equilibration are attributed to polyuronic acids (capacity: 0.3 milliequivalents per gram fresh cell walls). The second sites, are obtained after a long time of equilibration (capacity: 1.2 to 1.3 milliequivalents per gram, fresh cell walls). Titrations have been performed with different bases [KOH, NaOH, and Ca(OH)(2)] and under different ionic strengths.The results obtained with NaOH and KOH do not exhibit any difference of selectivity. Conversely, the sites have a much bigger affinity for the Ca(2+) ions than for the monovalent ones. The apparent pKa of the uronic acids was estimated to lie between 3.0 and 3.4; this is consistent with the values obtained with polyuronic acid solutions. PMID:16660868

Morvan, C; Demarty, M; Thellier, M

1979-06-01

173

Direct measurement of protein binding energetics by isothermal titration calorimetry  

Microsoft Academic Search

Of all the techniques that are currently available to measure binding, isothermal titration calorimetry is the only one capable of measuring not only the magnitude of the binding affinity but also the magnitude of the two thermodynamic terms that define the binding affinity: the enthalpy (?H) and entropy (?S) changes. Recent advances in instrumentation have facilitated the development of experimental

Stephanie Leavitt; Ernesto Freire

2001-01-01

174

Using Spreadsheets to Produce Acid-Base Titration Curves.  

ERIC Educational Resources Information Center

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

Cawley, Martin James; Parkinson, John

1995-01-01

175

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

PubMed

The most commonly used chondroitin sulfate (CS) assay method is cetylpyridinium chloride (CPC) titration. Cellulose acetate membrane electrophoresis (CAME) is the technique used for detection of impurities in the U.S. Pharmacopeia's CS monograph. Because CPC titration is a relatively nonspecific quantitative technique, the apparent amount of CS as determined by CPC titration alone may not reflect the true amount of CS due to possible interference with the CPC assay by impurities that contain CPC titratable functional groups. When CAME is used in conjunction with CPC titration, certain non-CS and adulterants can be visualized and estimated, and a true value for CS can be assigned once the presence of these non-CS impurities has been ruled out. This study examines conjunct application of CPC and CAME in ascertaining CS assay and purity in the presence of certain adulterants. These include propylene glycol alginate sulfate sodium, known in commerce as alginic sodium diester (ASD), and Zero One (Z1), a water-soluble agent newly reported in the CS marketplace and subsequently identified as sodium hexametaphosphate. ASD, Z1, and CS are similar in physical appearance and solubility in water and ethanol. They are also titratable anions and form ionic pairs with CPC, therefore interfering with the CPC titration assay for CS CAME separates these adulterants from each other and from CS by differences in their electrophoretic mobility. CAME is able to detect these impurities in CS at levels as low as 0.66% by weight. Although it is recommended that a method for detecting impurities (e.g., CAME) be used in cormbination with relatively nonspecific assay methods such as CPC titration, this is seldom done in practice. Assay results for CS derived fromn CPC titration may, therefore, be misleading, leaving the CS supply chain vulnerable to adulteration. In this study, the authors investigated ASD and Z1 adulteration of CS and developed an electrophoretic separation of these adulterants in CS and procedures to isolate ASD from CS matrixes containing these adulterants. The authors describe in this paper utilization of an orthogonal approach to establish the identity of Z1 as sodium hexametaphosphate and to confirm the identity of ASD, including ethanol fractionation, FTIR spectroscopy, differential scanning calorimetry, and NMR spectroscopy. The authors suggest that CAME is a cost-effective and easy to use methodfor detecting certain impurities in CS raw ingredients and recommend that CPC and CAME be used in combination by QC laboratories as a means of effectively deterring the practice of adulterating CS raw materials with the known adulterants ASD and Z1 and/or other non-chondroitin substances that can be separated from CSby CAME and that exhibit CPC titration behavior similar to CS. PMID:25372663

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

2014-01-01

176

Some aspects of the use of heteropoly anions in elemental analysis by simple potentiometric ion-pair formation-based titration.  

PubMed

The possibility of the use of heteropoly anions formed by addition of phosphate to the solutions of either molybdate or tungstate in the determination of phosphorus by the simple method of potentiometric titration was studied. The heteropoly anions are titrated on the ion-pairing principle using a titrant containing a lipophilic counter-ion, i.e. 1-(ethoxycarbonyl)pentadecyltrimethylammonium bromide (Septonex), the titration being monitored by carbon paste electrode, although other liquid membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption vs. concentration are not linear, but allow one to evaluate the content of phosphorus. Similar procedures, when optimized, should be elaborated for determination of numerous other elements forming heteropoly anions. PMID:18967295

Vytras, K; Jezková, J; Skorepa, J

1998-08-01

177

Automated Potentiometric Titrations in KCl/Water-Saturated Octanol: Method for Quantifying Factors Influencing Ion-Pair Partitioning  

PubMed Central

The knowledge base of factors influencing ion pair partitioning is very sparse, primarily because of the difficulty in determining accurate log PI values of desirable low molecular weight (MW) reference compounds. We have developed a potentiometric titration procedure in KCl/water-saturated octanol that provides a link to log PI through the thermodynamic cycle of ionization and partitioning. These titrations have the advantage of being independent of the magnitude of log P, while maintaining a reproducibility of a few hundredths of a log P in the calculated difference between log P neutral and log P ion pair (diff (log PN???I)). Simple model compounds can be used. The titration procedure is described in detail, along with a program for calculating pKa?? values incorporating the ionization of water in octanol. Hydrogen bonding and steric factors have a greater influence on ion pairs than they do on neutral species, yet these factors are missing from current programs used to calculate log PI and log D. In contrast to the common assumption that diff (log PN???I) is the same for all amines, they can actually vary more than 3 log units, as in our examples. A major factor affecting log PI is the ability of water and the counterion to approach the charge center. Bulky substituents near the charge center have a negative influence on log PI. On the other hand, hydrogen bonding groups near the charge center have the opposite effect by lowering the free energy of the ion pair. The use of this titration method to determine substituent ion pair stabilization values (IPS) should bring about more accurate log D calculations and encourage species-specific QSAR involving log DN and log DI. This work also brings attention to the fascinating world of nature’s highly stabilized ion pairs. PMID:19265385

2009-01-01

178

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

PubMed

The baculovirus expression vector system (BEVS) is one of the most powerful methods for production of recombinant proteins for research or commercial purposes. Titration of viable virus in insect cell culture is often required when BEVS is used for basic research or bioprocessing. An enzyme-linked immunosorbent spot (ELISPOT) assay using monoclonal antibodies against the major capsid protein VP39 of both Autographa californica nuclear polyhedrosis virus (AcMNPV) and Bombyx mori nuclear polyhedrosis virus (BmNPV) was developed for baculovirus quantitation at 48h post-infection. The titer was determined by visualizing infected insect cells as blue spots and automated spot counting was achieved with ELISPOT hardware and software. Log-scale comparison of the results between the ELISPOT assay and a conventional end point dilution assay using a fluorescent marker showed a good correlation for both AcMNPV (R(2)=0.9980, p<0.05) and BmNPV (R(2)=0.9834, p<0.05). In conclusion, a novel, rapid and semi-automated procedure for titrating baculovirus was developed based on the specific immunostaining of infected cells followed by automated spot counting. PMID:23274754

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

2013-03-01

179

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

E-print Network

by potentiometric titration of ion-exchanged Hp. Conditions for complex formation with SA were qualitativelyBinding of Bovine Serum Albumin to Heparin Determined by Turbidimetric Titration and Frontal

Dubin, Paul D.

180

The ion-sensitive field effect transistor in rapid acid-base titrations  

Microsoft Academic Search

Ion-sensitive field effect transistors (ISFETs) are used as the pH sensor in rapid acid—base titrations. Titration speeds at least five times greater than those with glass electrodes are possible for accuracies better than ±1%.

M. Bos; P. Bergveld; Veen-Blaauw van A. M. W

1979-01-01

181

PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS  

SciTech Connect

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

Brown, Robert A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)], E-mail: rbrown@stsci.edu

2009-09-10

182

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.

2014-01-01

183

Difference image analysis: The interplay between the photometric scale factor and systematic photometric errors  

E-print Network

Context: Understanding the source of systematic errors in photometry is essential for their calibration. Aims: We investigate how photometry performed on difference images can be influenced by errors in the photometric scale factor. Methods: We explore the equations for difference image analysis (DIA) and we derive an expression describing how errors in the difference flux, the photometric scale factor and the reference flux are propagated to the object photometry. Results: We find that the error in the photometric scale factor is important, and while a few studies have shown that it can be at a significant level, it is currently neglected by the vast majority of photometric surveys employing DIA. Conclusions: Minimising the error in the photometric scale factor, or compensating for it in a post-calibration model, is crucial for reducing the systematic errors in DIA photometry.

Bramich, D M; Alsubai, K A; Mislis, D; Parley, N

2015-01-01

184

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

PubMed

An express method for determination of acidity constants of organic acids, based on the analysis of the integral transmittance vs. pH dependence is developed. The integral value is registered as a photocurrent of photometric device simultaneously with potentiometric titration. The proposed method allows to obtain pKa using only simple and low-cost instrumentation. The optical part of the experimental setup has been optimized through the exclusion of the monochromator device. Thus it only takes 10-15min to obtain one pKa value with the absolute error of less than 0.15 pH units. Application limitations and reliability of the method have been tested for a series of organic acids of various nature. PMID:25668697

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

2015-04-15

185

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

E-print Network

November 2004 Abstract The high-resolution potentiometric titration was used as a physico-chemical method Ltd. All rights reserved. Keywords: Gran's method; High-resolution potentiometric titration; Acidic and their polyelec- trolyte nature call for the application of the acid­base potentiometric titration method

Volesky, Bohumil

186

Potentiometric automatic titration (PAT) method to evaluate zero point of charge (ZPC) of variable charge soils  

Microsoft Academic Search

A potentiometric titration technique using an automatic titrator (PAT method) was evaluated for the determination of the ZPC of two different kinds of variable charge soils. The titration mode of PAT was proposed as follows: pre-equilibration for 2 min with continuous stirring, soil: solution ratio of 1 : 10, and cut off time (interval of titrant addition to the system)

Katsutoshi Sakurai; Yohichi Ohdate; Kazutake Kyuma

1989-01-01

187

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.

2012-01-01

188

The possibility of determining the activity coefficients of individual ions from acid-base titration data  

Microsoft Academic Search

A method is described for obtaining the activity coefficients of individual ions from experimental titration data. For this purpose, a general polyprotic acid-base-titration-curve equation is derived. The equation allows obtaining the dissociation equilibrium constants of the acid and the ratio of the activity coefficient of each ion to the activity coefficient of the undissociated acid directly from the titration data.

I. Jano; J. E. Hardcastle

1998-01-01

189

Free Software Development. 3. Numerical Description of Weak Acid with Weak Base Titration  

Microsoft Academic Search

The analytical methods of qualitative and quantitative determination of ions in solutions are very flexible to automation. The present work is focus on modeling the process of titration and presents a numerical simulation of acid-base titration. A PHP program to compute all iterations in titration process that solves a 3 th rank equation to find value of pH for was

Lorentz JÄNTSCHI; Horea Iustin

2002-01-01

190

SR-FTIR Study of Bacteria-Water Interactions: Acid-base Titration and Silification Experiments  

E-print Network

SR-FTIR Study of Bacteria-Water Interactions: Acid-base Titration and Silification Experiments/base titration and Si precipitation experiments. The objectives of this research are to identify the reactive through fluid cell with BaF2 and ZnSe windows separated by a 6 um mylar spacer. Acid-base titration and Si

191

Relations between Protonation Constants and Titration Curves in Polyprotic Acids: A Critical View  

E-print Network

Relations between Protonation Constants and Titration Curves in Polyprotic Acids: A Critical View G. In this paper, the relation between these pKa values and their relation to titration curves is discussed. Often inflection points of total and individual titration curves or the pH value where the proton binding site

Ullmann, G. Matthias

192

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.1 pseudoknot is the limiting step of the molecular mechanism. Last, as illustrated here, isothermal titration

Perreault, Jean-Pierre

193

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

E-print Network

Comparison 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 titration, whereas the so-called zeta potential is generally determined by electrokinetic techniques (e

Attard, Phil

194

Journal of Electroanalytical Chemistry 512 (2001) 8391 Faradaic impedance titration of pure 3-mercaptopropionic acid  

E-print Network

Journal of Electroanalytical Chemistry 512 (2001) 83­91 Faradaic impedance titration of pure 3-assembled monolayers (SAMs) have been studied using the faradaic impedance titration method. The Fe(CN)6 3- is used strength. The in-plane electrostatic force effect, which causes a broadening of the titration curves

Kwak, Juhyoun

195

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

E-print Network

Propagation of error in fulvic acid titration data: a comparison of three analytical methods but little consideration has been given to the magnitude of error in the resulting titration data. Most of random instrumenterror into a titrationdata set is not uniform throughout a titration and the pattern

Morel, François M. M.

196

NATURE BIOTECHNOLOGY VOLUME 24 NUMBER 9 SEPTEMBER 2006 1123 Using RNA sample titrations to assess  

E-print Network

NATURE BIOTECHNOLOGY VOLUME 24 NUMBER 9 SEPTEMBER 2006 1123 Using RNA sample titrations to assess assessed the utility of RNA titration samples for evaluating microarray platform performance and the impact samples and two titration mixtures of these samples. Focusing on 12,091 genes common across all platforms

Cai, Long

197

A LABORATORY REFERENCE VACCINE TO TITRATE IMMUNOGENIC ACTIVITY OF ANTIBRUCELLA VACCINES IN MICE  

E-print Network

A LABORATORY REFERENCE VACCINE TO TITRATE IMMUNOGENIC ACTIVITY OF ANTIBRUCELLA VACCINES IN MICE'expression de l'activité par rapport à un système unitaire. Titration of immunogenic activity of anti-Bru- cella reference vaccine. We describe here prepara- tion and titration of this vaccine. Materials and Methods

Boyer, Edmond

198

Linking Surface Potential and Deprotonation in Nanoporous Silica: Second Harmonic Generation and Acid/Base Titration  

E-print Network

and Acid/Base Titration R. Kramer Campen,,,§ Allison K. Pymer,,| Satoshi Nihonyanagi,, and Eric Borguet development in nanoporous silica. We do so using conventional titration techniques and a noninvasive, all by internal surface sites. Such a threshold pH, above which acid/base or ion titration curves of porous

Borguet, Eric

199

Dissecting electrostatic interactions in Bacillus circulans xylanase through NMR-monitored pH titrations  

E-print Network

-monitored pH titrations Lawrence P. McIntosh · Daigo Naito · Simon J. Baturin · Mark Okon · Manish D. Joshi.V. 2011 Abstract NMR-monitored pH titration curves of proteins provide a rich source of structural to analyze the biphasic titrations exhibited by the side chain 13 Cc nuclei of the nucleophilic Glu78

McIntosh, Lawrence P.

200

On-Chip Titration of an Anticoagulant Argatroban and Determination of the Clotting Time within  

E-print Network

On-Chip Titration of an Anticoagulant Argatroban and Determination of the Clotting Time within was developed to titrate an anticoagulant (argatroban) into blood samples and to measure the clotting time using) titration of argatroban (0-1.5 µg/mL) into plugs and measurement of the resulting APTTs at room temperature

Ismagilov, Rustem F.

201

Polyelectrolyte Titration: Theory and Experiment Itamar Borukhov,*, David Andelman,,| Regis Borrega, Michel Cloitre, Ludwik Leibler, and  

E-print Network

Polyelectrolyte Titration: Theory and Experiment Itamar Borukhov,*, David Andelman,,| Regis Borrega; In Final Form: July 31, 2000 Titration of methacrylic acid/ethyl acrylate copolymers is studied experimentally and theoretically. At low salt concentrations, this polyacid exhibits a plateau in the titration

Andelman, David

202

Titrating PolyelectrolytessVariational Calculations and Monte Carlo Simulations Bo Jo1nsson*, and Magnus Ullner  

E-print Network

Titrating PolyelectrolytessVariational Calculations and Monte Carlo Simulations Bo Jo1nsson Variational methods are used to calculate structural and thermodynamical properties of a titrating; i.e., titratable groups in a polymer will exchange protons with the solution and the polymer net

Peterson, Carsten

203

New Concepts A Novel View of pH Titration in Biomolecules  

E-print Network

New Concepts A Novel View of pH Titration in Biomolecules Alexey Onufriev, David A. Case,* and G 31, 2001 ABSTRACT: When individual titratable sites in a molecule interact with each other, their pH titration can be considerably more complex than that of an independent site described by the classical

Onufriev, Alexey

204

proteinsSTRUCTURE O FUNCTION O BIOINFORMATICS Titration_DB: Storage and analysis of  

E-print Network

proteinsSTRUCTURE O FUNCTION O BIOINFORMATICS Titration_DB: Storage and analysis of NMR-monitored protein pH titration curves Damien Farrell,1 Emanuel Sa´ Miranda,1 Helen Webb,1 Nikolaj Georgi,1 Peter B display pH-dependent properties due to titration of amino acid side chains and termini, coupled

McIntosh, Lawrence P.

205

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

E-print Network

1 Age adapted morphine titration produces equivalent analgesia and side effects in younger: To determine efficacy and safety of postoperative titrated morphine in elderly patients when intravenous complaining of pain received morphine until adequate pain relief. Intravenous morphine was titrated as 3 mg

Boyer, Edmond

206

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

E-print Network

Age-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 was titrated as 3 mg boluses for young (age 65 yrs) and 2 mg for elderly patients (> 65 yrs) respectively

Paris-Sud XI, Université de

207

Relations between Protonation Constants and Titration Curves in Polyprotic Acids: A Critical View  

E-print Network

Relations between Protonation Constants and Titration Curves in Polyprotic Acids: A Critical View G. B November 20, 2002 Supporting information 1 #12;1. Inflection Points of Titration Curves Monoprotic Acid. The titration curve of a monoprotic acid is given by eq 1 which is algebraically equivalent

Ullmann, G. Matthias

208

Spectro-photometric distances to stars: a general-purpose Bayesian approach  

E-print Network

We have developed a procedure that estimates distances to stars using measured spectroscopic and photometric quantities. It employs a Bayesian approach to build the probability distribution function over stellar evolutionary models given the data, delivering estimates of expected distance for each star individually. Our method provides several alternative distance estimates for each star in the output, along with their associated uncertainties. The code was first tested on simulations, successfully recovering input distances to mock stars with errors that scale with the uncertainties in the adopted spectro-photometric parameters, as expected. The code was then validated by comparing our distance estimates to parallax measurements from the Hipparcos mission for nearby stars (studied open and globular clusters. The photometric data of these reference samples cover both the optical and near infra-red wavelengths. The...

Santiago, Basílio X; Anders, Friedrich; Chiappini, Cristina; Girardi, Léo; Rocha-Pinto, Helio J; Balbinot, Eduardo; da Costa, Luiz N; Maia, Marcio A G; Schultheis, Mathias; Steinmetz, Matthias; Miglio, Andrea; Montalbán, Josefina; Schneider, Donald P; Beers, Timothy C; Frinchaboy, Peter M; Lee, Young Sun; Zasowski, Gail

2015-01-01

209

Impact of subsolar metallicities on photometric redshifts  

NASA Astrophysics Data System (ADS)

With the advent of deep photometric surveys the use of photometric redshifts, obtained with a variety of techniques, has become more and more widespread. Giving access to galaxies with a wide range of luminosities out to high redshifts, these surveys include many faint galaxies with significantly subsolar metallicities. We use our chemically consistent (CC) galaxy evolutionary synthesis code GALEV to produce a large grid of template spectral energy distributions (SEDs) for galaxies of spectral types E and Sa through Sd - one accounting in a CC way for the increasing initial metallicities of successive stellar generations, the other one for exclusively solar metallicities - for comparison. We use our new photometric redshift code GAZELLE based on the comparison of observed and model SEDs. Comparing the photometric redshifts obtained using solar-metallicity templates when working on a catalogue of artificially created CC SEDs, typical for low-metallicity local late-type galaxies and for intrinsically low-luminosity, and hence low-metallicity, galaxies in the high-redshift universe, we find a significant bias resulting from this metallicity mismatch. This bias consists of a systematic underestimate of the photometric redshift by typically ?z ~ 0.1...0.2 until z ~ 1.2, depending on galaxy type, of distant, faint and low-metallicity galaxies if analysed with solar-metallicity templates.

Kotulla, Ralf; Fritze, Uta

2009-02-01

210

Derivative analysis of potentiometric titration data to obtain protonation constants  

SciTech Connect

A methodology is described to calibrate glass electrodes and to analyze potentiometric titration data to calculate protonation constants. The analysis uses the variation of dV/dpH with titrant addition in terms of two physical parameters which involve the concentrations of H{sup +}, OH{sup -}, and H{sub m}A. The data for titration of acetic acid and 8-hydroxyquinoline in 0.10-5.0 m NaCl media are analyzed by this method to obtain the stoichiometric protonation constants of the acids, the ionization constants of water, and the parameters s and b in the pH electrode calibration equation, pcH = spH{sub m} + b, where pcH = -log[H{sup +}], pH{sub m} is the pH meter reading. 31 refs., 3 figs., 6 tabs.

Chen, J.F.; Xia, Y.X.; Choppin, G.R. [Florida State Univ., Tallahassee, FL (United States)] [Florida State Univ., Tallahassee, FL (United States)

1996-11-15

211

Potentiometric titrations of rutile suspensions to 250 C  

SciTech Connect

A stirred hydrogen electrode concentration cell was used to conduct potentiometric titrations of rutile suspensions from 25 to 250 C in NaCl and tetramethylammonium chloride media (0.03 to 1.1 m). Hydrothermal pretreatment of the rutile improved titration reproducibility, decreased titration hysteresis, and facilitated determination of the point of zero net proton charge (pHznpc). These pHznpc values are 5.4, 5.1, 4.7, 4.4, 4.3 ({+-} 0.2 pH units), and 4.2 ({+-} 0.3 pH units) at 25, 50, 100, 150, 200, and 250 C, respectively. The difference between these pHznpc values and 1/2 pK{sub w} (the neutral pH of water) is rather constant between 25 and 250 C ({minus} 1.45 {+-} 0.2). This constancy is useful for predictive purposes and, more fundamentally, may reflect similarities between the hydration behavior of surface hydroxyl groups and water. A three-layer, 1pKa surface complexation model with three adjustable parameters (two capacitance values and one counterion binding constant) adequately described all titration data. The most apparent trend in these data for pH values greater than the pHznpc was the increase in proton release (negative surface charge) with increasing temperature. This reflects more efficient screening by Na{sup +} relative to Cl{sup {minus}}. Replacing Na{sup +} with the larger tetramethylammonium cation for some conditions resulted in decreased proton release due to the less efficient screening of negative surface charge by this larger cation.

Machesky, M.L. [Illinois State Water Survey, Champaign, IL (United States)] [Illinois State Water Survey, Champaign, IL (United States); Wesolowski, D.J.; Palmer, D.A. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.] [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.; Ichiro-Hayashi, Ken [Tohoku Univ., Sendai (Japan). Inst. of Mineralogy, Petrology and Economic Geology] [Tohoku Univ., Sendai (Japan). Inst. of Mineralogy, Petrology and Economic Geology

1998-04-15

212

New developments for the numerical analysis of spectrophotometric titrations  

Microsoft Academic Search

Spectrophotometric titrations are a valuable tool for the investigation of solution equilibria. Data acquisition and recent developments on methods for the analysis of the measurements are discussed in this contribution. Hard-modeling methods are based on non-linear least-squares fitting, and algorithms have been developed which can cope with the large amount of data and parameters of multiwavelength or multivariate measurements. Good

Raylene M. Dyson; Porn Jandanklang; Marcel Maeder; Caroline J. Mason; Andrew Whitson

1999-01-01

213

A high frequency titration of indium with benzenephosphinic acid  

E-print Network

for iron. Banks, pennell, and gkoog (3) followed this with a publication of results obtained in determining what other ious would effect the iron determination by precipitation, or by coprecipitation, or by complex foramtion with benseaephosphinic acid... that there is no coprecipitation. The 25T, excess of the acid shows that essentially the precipitation of indium as indium benzene- pbosphinate is complete at a stoichiometric point. Benzenephosphinic acid should serve as a precipitating agent in a volumetric titration...

Keilt, Francis Xavier

1960-01-01

214

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 (V<12). Testing this method on SDSS photometric telescope observations, I find that the photometric accuracy for a single star is usually about 0.12, 0.12, 0.10 and 0.08 mag (1 sigma), for the g, r, i, and z-bands, respectively. However, by using ~10 such stars, the typical errors per calibrated 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

2008-09-25

215

The potentiometric titration of fluoride using pH electrodes  

SciTech Connect

Sodium fluoride solutions with an initial pH of 4.46 yielded poorly defined endpoint breaks with a pH electrode system and Ce(III) or La(III) as titrants. At this initial pH, however, the fluoride ISE yielded acceptable S-shaped titration curves. At an initial pH of 6.30, both electrode systems and titrant combinations yielded acceptable endpoint breaks and titration curves. While a partially nonaqueous medium (50% methanol) enhanced the steepness of the endpoint breaks, the standard deviation also increased. This was possibly caused by evaporation of some of the solvent. We therefore do not see the necessity for, nor recommend a partially nonaqueous medium. There is no advantage in using Ce(III) rather than La(III) as titrant. Increasing the initial pH from 4.46 to 6.3 decreased the mean normality of the titrant (or increased the titration volume) for both electrode systems and titrants. We therefore recommend that the sodium fluoride standard solutions be adjusted to the same pH as the samples to be determined. For the most accurate results, the standardization should be done with a good approximation of the salt content of the unknown solution.

Selig, W.S.

1987-07-01

216

Photometric diversity of terrains on Triton  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

217

Photometric redshifts for the CFHTLS-Wide  

E-print Network

We want to derive bias free, accurate photometric redshifts for those fields of the CFHTLS-Wide data which are covered in the u*, g', r', i' and z' filters and are public on January 2008. These are 37 square degrees in the W1, W3 and W4 fields with photometric data for a total of 2.597.239 galaxies. We use the photometric redshift code PHOTO-z of Bender et al. (2001). We compare our redshifts for the W1, W3 and W4 fields to about 7500 spectroscopic redshifts from the VVDS therein. For galaxies with 17.5 eta~2 % for W1, sigma=0.037, eta~2% for W3 and sigma=0.035, eta~2.5 % outliers for W4 fields. For the total galaxy sample with about 9000 spectroscopic redshifts from VVDS, DEEP2 or SDSS we obtain a sigma=0.04 and eta~5.7% for the PHOTO-z redshifts. We consider the photometric redshifts of Erben et al. (2008) which were obtained with exactly the same photometric catalog using the BPZ-redshift code and compare them with our computed redshifts. We also merge the subsample with good photometric redshifts from PHOTO-z with that one from BPZ to obtain a sample which then contains 'secure' redshifts according to both the PHOTO-z and the BPZ codes. This sample contains about 6100 spectra and the photometric redshift qualities become sigma=0.037 and eta~1.0% for our PHOTO-z redshifts. We conclude that this work provides a bias free, low dispersion photometric redshift catalog, that we have criteria at hand to select a 'robust' subsample with fewer outliers. Such a subsample is very useful to study the redshift dependent growth of the dark matter fluctuations with weak lensing cosmic shear analyses or to investigate the redshift dependent weak lensing signal behind clusters of galaxies in the framework of dark energy equation of state constraints.

Fabrice Brimioulle; Michael Lerchster; Stella Seitz; Ralf Bender; Jan Snigula

2008-11-19

218

Reddening Behaviors of Galaxies in the SDSS Photometric System  

E-print Network

We analyze the behaviors of reddening vectors in the SDSS photometric system for galaxies of different morphologies, ages, and redshifts. As seen in other photometric systems, the dependence of reddening on the spectral energy distribution (SED) and the nonlinearity of reddening are likewise non-negligible for the SDSS system if extinction is significant (~> 1 mag). These behaviors are most significant for the g filter, which has the largest bandwidth-to-central wavelength ratio among SDSS filters. The SDSS colors involving adjacent filters show greater SED-dependence and nonlinearity. A procedure for calculating the correct amount of extinction from an observed color excess is provided. The relative extinctions between (i.e., the extinction law for) SDSS filters given by Schlegel et al., which were calculated with an older version of filter response functions, would underestimate the amount of extinction in most cases by ~5 to 10 % (maximum ~20 %). We recommend A/A_{5500} values of 1.574, 1.191, 0.876, 0.671 & 0.486 for the u, g, r, i, & z filters, respectively, as a representative extinction law for the SDSS galaxies with a small extinction (i.e., for cases where the nonlinearity and SED-dependence of the reddening is not important). The dependence of reddening on redshift at low extinction is the largest for colors involving the g filter as well, which is due to the Balmer break.

Sungsoo S. Kim; Myung Gyoon Lee

2008-05-01

219

Kohoutek, photometric photography experiment (S233)  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

220

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

2014-02-01

221

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

1995-01-01

222

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.

1992-01-01

223

Sheppard et al.: Photometric Lightcurves 129 Photometric Lightcurves of Transneptunian Objects  

E-print Network

Andalucia We discuss the transneptunian objects and Centaur rotations, shapes, and densities as deter- mined to be significantly slower than the main- belt asteroids of similar size. The photometric ranges have been found

Sheppard, Scott S.

224

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.

2008-12-01

225

A titration model for evaluating calcium hydroxide removal techniques  

PubMed Central

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

PHILLIPS, Mark; McCLANAHAN, Scott; BOWLES, Walter

2015-01-01

226

PAPER www.rsc.org/pps | Photochemical & Photobiological Sciences Theoretical investigation of the behavior of titratable groups in proteins  

E-print Network

of the behavior of titratable groups in proteins Astrid R. Klingen,a Elisa Bombardaa,b and G. Matthias Ullmann April 2006 DOI: 10.1039/b515479k This paper presents a theoretical analysis of the titration behavior of strongly interacting titratable residues in proteins. Strongly interacting titratable residues exist

Ullmann, G. Matthias

227

A New Perspective on Uncalibrated Photometric Stereo Thoma Papadhimitri  

E-print Network

study. In this paper, we introduce a novel insight in uncali- brated photometric stereoA New Perspective on Uncalibrated Photometric Stereo Thoma Papadhimitri University of Bern Bern in uncalibrated photometric stereo under the perspective projection model. Our analysis is based on establishing

Jäger, Gerhard

228

High frequency titration of amines in nonaqueous solutions  

E-print Network

appeared to be more gradual than in the previous instances. Por this reason the high frequency end pbint was assumed to be the correct once Attempts were made to titrate both ortho- and ~ara-nitroaniline, but they were unsuccessful. This was apparently... were obtained, for n-propylamine, di-n-propylamine, triethylamine, ethanol- amine, and pyridine. Pair results were obt aimed for aniline and m-bromoaniline; however, ortho- and para- nitroaniline could not be titra*ed by this method. An attempt...

Witmer, William Byron

1958-01-01

229

Succinylated machined corncobs: Titration and heavy metal ion binding characteristics  

SciTech Connect

The use of inexpensive natural materials for waste water treatment is economically attractive. In this study chemical modifications of an agricultural by-product, Lite-R-Cobs, were explored to increase its utility for reduction of metal ions in waste water effluent. Corn cob particles have been succinylated to increase their capacity for binding heavy metal ions. The carboxyl groups introduced into this cellulosic material were quantitated by base titration. Equilibrium metal ion binding characteristics of the material was studied for Cu{sup 2+}, Cd{sup 2+}, and Ni{sup 2+} ions.

McCall, R.C.; Getman, T.D.; Hunsley, J.R. [Southern Illinois Univ., Edwardsville, IL (United States)

1996-10-01

230

Isothermal Titration Calorimetry of Membrane Proteins – Progress and Challenges  

PubMed Central

Summary Integral membrane proteins, including G protein-coupled receptors (GPCR) and ion channels, mediate diverse biological functions that are crucial to all aspects of life. The knowledge of the molecular mechanisms, and in particular, the thermodynamic basis of the binding interactions of the extracellular ligands and intracellular effector proteins is essential to understand the workings of these remarkable nanomachines. In this review, we describe how isothermal titration calorimetry (ITC) can be effectively used to gain valuable insights into the thermodynamic signatures (enthalpy, entropy, affinity, and stoichiometry), which would be most useful for drug discovery studies, considering that more than 30% of the current drugs target membrane proteins. PMID:23747362

Rajarathnam, Krishna; Rösgen, Jörg

2013-01-01

231

A Dibasic Acid Titration for the Physical Chemistry Laboratory  

NASA Astrophysics Data System (ADS)

A physical chemistry laboratory experiment is described in which both pK, and pK2 are determined for weak dibasic acids with closely spaced acid dissociation constants. The method is acid-base titration. Data are acquired by a computer interfaced to a pH meter, however emphasis on experimental technique is retained by requiring students to manipulate a buret, read it, and manually enter the volumes into the computer. The computer is then used to ease the burden of tedious and repetitious calculations which yield the two pKa values.

Brabson, G. D.; Clay, J. T.; Walters, E. A.

1995-07-01

232

Applications of Isothermal Titration Calorimetry in RNA Biochemistry and Biophysics  

PubMed Central

Isothermal titration calorimetry (ITC) has been applied to the study of proteins for many years. Its use in the biophysical analysis of RNAs has lagged significantly behind its use in protein biochemistry, however, in part because of the relatively large samples required. As the instrumentation has become more sensitive, the ability to obtain high quality data on RNA folding and RNA ligand interactions has improved dramatically. This review provides an overview of the ITC experiment and describes recent work on RNA systems that have taken advantage of its versatility for the study of small molecule binding, protein binding, and the analysis of RNA folding. PMID:17671974

Feig, Andrew L.

2008-01-01

233

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

NASA Astrophysics Data System (ADS)

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 KIO3 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.

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

2011-11-01

234

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

PubMed

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

2013-12-01

235

Constant-pH molecular dynamics using stochastic titration  

NASA Astrophysics Data System (ADS)

A new method is proposed for performing constant-pH molecular dynamics (MD) simulations, that is, MD simulations where pH is one of the external thermodynamic parameters, like the temperature or the pressure. The protonation state of each titrable site in the solute is allowed to change during a molecular mechanics (MM) MD simulation, the new states being obtained from a combination of continuum electrostatics (CE) calculations and Monte Carlo (MC) simulation of protonation equilibrium. The coupling between the MM/MD and CE/MC algorithms is done in a way that ensures a proper Markov chain, sampling from the intended semigrand canonical distribution. This stochastic titration method is applied to succinic acid, aimed at illustrating the method and examining the choice of its adjustable parameters. The complete titration of succinic acid, using constant-pH MD simulations at different pH values, gives a clear picture of the coupling between the trans/gauche isomerization and the protonation process, making it possible to reconcile some apparently contradictory results of previous studies. The present constant-pH MD method is shown to require a moderate increase of computational cost when compared to the usual MD method.

Baptista, António M.; Teixeira, Vitor H.; Soares, Cláudio M.

2002-09-01

236

Standard test method for uranium by Iron (II) reduction in phosphoric acid followed by chromium (VI) titration in the presence of vanadium  

E-print Network

1.1 This test method, commonly referred to as the Modified Davies and Gray technique, covers the titration of uranium in product, fuel, and scrap materials after the material is dissolved. The test method is versatile and has been ruggedness tested. With appropriate sample preparation, this test method can give precise and unbiased uranium assays over a wide variety of material types (1, 2). Details of the titration procedure in the presence of plutonium with appropriate modifications are given in Test Method C1204. 1.2 Uranium levels titrated are usually 20 to 50 mg, but up to 200 mg uranium can be titrated using the reagent volumes stated in this test method. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determ...

American Society for Testing and Materials. Philadelphia

2011-01-01

237

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)

1994-01-01

238

Photometric reverberation mapping of active galactic nuclei  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

239

Kernel PCA for Supernovae Photometric Classification  

NASA Astrophysics Data System (ADS)

In this work, we propose the use of Kernel Principal Component Analysis (KPCA) combined with k = 1 nearest neighbor algorithm (1NN) as a framework for supernovae (SNe) photometric classification. It is specially recommended for analysis where the user is interested in high purity in the final SNe Ia sample. Our method provide good purity results in all data sample analyzed, when SNR>=5. As a consequence, we can state that if a sample as the Supernova Photometric Classification Challenge were available today, we would be able to classify ~ 15% of the initial data set with purity higher than 90%. This makes our algorithm ideal for a first approach to an unlabeled data set or to be used as a complement in increasing the training sample for other algorithms. Results are sensitive to the information contained in each light curve, as a consequence, higher quality data (low noise) leads to higher successful classification rates.

Ishida, Emille E. O.

2015-03-01

240

SDSS Data Management and Photometric Quality Assessment  

E-print Network

We summarize the Sloan Digital Sky Survey data acquisition and processing steps, and describe runQA, a pipeline designed for automated data quality assessment. In particular, we show how the position of the stellar locus in color-color diagrams can be used to estimate the accuracy of photometric zeropoint calibration to better than 0.01 mag in 0.03 deg2 patches. Using this method, we estimate that typical photometric zeropoint calibration errors for SDSS imaging data are not larger than ~0.01 mag in the g, r, and i bands, 0.02 mag in the z band, and 0.03 mag in the u band (root-mean-scatter for zeropoint offsets).

Z. Ivezic; R. H. Lupton; D. Schlegel; B. Boroski; J. Adelman-McCarthy; B. Yanny; S. Kent; C. Stoughton; D. Finkbeiner; N. Padmanabhan; C. M. Rockosi; J. E. Gunn; G. R. Knapp; M. A. Strauss; G. T. Richards; D. Eisenstein; T. Nicinski; S. J. Kleinman; J. Krzesinski; P. R. Newman; S. Snedden; A. R. Thakar; A. Szalay; J. A. Munn; J. A. Smith; D. Tucker; B. C. Lee

2004-10-07

241

SDSS data management and photometric quality assessment  

Microsoft Academic Search

We summarize the Sloan Digital Sky Survey data acquisition and processing steps, and describe runQA, a pipeline designed for automated data quality assessment. In particular, we show how the position of the stellar locus in color-color diagrams can be used to estimate the accuracy of photometric zeropoint calibration to better than 0.01 mag in 0.03 deg2 patches. Using this method,

Z. Ivezic; R. H. Lupton; D. Schlegel; B. Boroski; J. Adelman-McCarthy; B. Yanny; S. Kent; C. Stoughton; D. Finkbeiner; N. Padmanabhan; C. M. Rockosi; J. E. Gunn; G. R. Knapp; G. T. Richards; D. Eisenstein; T. Nicinski; S. J. Kleinman; J. Krzesinski; P. R. Newman; S. Snedden; A. R. Thakar; A. Szalay; J. A. Smith; D. Tucker; B. C. Lee

2004-01-01

242

Photometric Redshifts in the Hubble Deep Field  

E-print Network

Photometric redshifts for galaxies in the Hubble Deep Field are measured. Luminosity functions show steepening of the faint-end slope and mild brightening of M* out to z~3, followed by a decline at higher z; an excess of faint, star-forming galaxies is seen at low z. Our results are consistent with the formation of large galaxies at z=2-3, followed by that of dwarfs at z<1.

M. J. Sawicki; H. Lin; H. K. C. Yee

1996-10-03

243

Photometric Defocus Observations of Transiting Extrasolar Planets  

NASA Astrophysics Data System (ADS)

We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6 m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocus technique, allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate that this technique is capable of obtaining a root-mean-square scatter of sub-millimagnitude order over several hours for a V ~10 host star, typical for transiting planets detected from ground-based survey facilities. We compared our results with transit observations from a telescope operated in in-focus mode. High photometric precision was obtained due to the collection of a larger amount of photons, resulting in a higher signal compared to other random and systematic noise sources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by exposing the same pixels on the CCD. Furthermore, a longer exposure time helps reduce the effect of scintillation noise which otherwise has a significant effect for small-aperture telescopes operated in in-focus mode. Finally we present the results of modelling four light-curves in which a root-mean-square scatter of 0.70 to 2.3 milli-magnitudes was achieved.

Hinse, Tobias C.; Han, Wonyong; Yoon, Joh-Na; Lee, Chung-Uk; Kim, Yong-Gi; Kim, Chun-Hwey

2015-03-01

244

Can Selforganizing Maps Accurately Predict Photometric Redshifts?  

NASA Technical Reports Server (NTRS)

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

Way, Michael J.; Klose, Christian

2012-01-01

245

Photometric defocus observations of transiting extrasolar planets  

E-print Network

We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocus technique allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate that this technique is capable of obtaining a root-mean-square scatter of order sub-millimagnitude over several hours for a V $\\sim$ 10 host star typical for transiting planets detected from ground-based survey facilities. We compare our results with transit observations with the telescope operated in in-focus mode. High photometric precision is obtained due to the collection of a larger amount of photons resulting in a higher signal compared to other random and systematic noise sources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by probing the same pixels on the CCD. Furthermore, a longer exposure time helps reducing the eff...

Hinse, Tobias C; Yoon, Jo-Na; Lee, Chung-Uk; Kim, Yong-Gi; Kim, Chun-Hwey

2015-01-01

246

Improving LSST Photometric Calibration with Gaia Data  

NASA Astrophysics Data System (ADS)

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

Axelrod, Tim; Miller, Calder

2014-12-01

247

Monitoring the photometric behavior of OmegaCAM with Astro-WISE  

NASA Astrophysics Data System (ADS)

The OmegaCAM wide-field optical imager is the sole instrument on the VLT Survey Telescope at ESO's Paranal Observatory. The instrument, as well as the telescope, have been designed for surveys with very good, natural seeing-limited image quality over a 1 square degree field. OmegaCAM was commissioned in 2011 and has been observing three ESO Public Surveys in parallel since October 15, 2011. We use the Astro-WISE information system to monitor the calibration of the observatory and to produce the Kilo Degree Survey (KiDS). Here we describe the photometric monitoring procedures in Astro-WISE and give a first impression of OmegaCAM's photometric behavior as a function of time. The long-term monitoring of the observatory goes hand in hand with the KiDS survey production in Astro-WISE. KiDS is observed under partially non-photometric conditions. Based on the first year of OmegaCAM operations it is expected that a ˜ 1-2 % photometric homogeneity will be achieved for KiDS.

Verdoes Kleijn, G. A.; Kuijken, K. H.; Valentijn, E. A.; Boxhoorn, D. R.; Begeman, K. G.; Deul, E. R.; Helmich, E. M.; Rengelink, R.

2013-01-01

248

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

2012-01-01

249

Formation and stability of nucleotide complexes: Raman titration investigation  

NASA Astrophysics Data System (ADS)

In order to monitor the formation of complexes between modified and wild type nucleotides, a concept based on spectroscopic titration combined with factor analysis data treatment has been developed. A set of samples containing two homopolynucleotides with complementary bases at various concentration ratios has been prepared. Other conditions, i.e. total nucleotide concentration, temperature, ionic strength, divalent ions percentage and pH, were conserved. The series of Raman and UV-absorption spectra obtained from these samples have been treated by factor analysis and the results then fitted to the equilibrium equations of 1 : 1 and 1 : 2 complexes. By this way, spectra of individual unpaired nucleotides, 1 : 1 and 1 : 2 complexes, and values of the stability constants can be determined at the same time. While the former characterise the structure of the individual species, the latter parameters implicate their percentage in each sample. The approach has been tested on a poly(rA)-poly(rU) model system.

Hanuš, J.; Št?pánek, J.; Turpin, P.-Y.; Bok, J.

1999-05-01

250

Ultrasensitivity by molecular titration in spatially propagating enzymatic reactions.  

PubMed

Delineating design principles of biological systems by reconstitution of purified components offers a platform to gauge the influence of critical physicochemical parameters on minimal biological systems of reduced complexity. Here we unravel the effect of strong reversible inhibitors on the spatiotemporal propagation of enzymatic reactions in a confined environment in vitro. We use micropatterned, enzyme-laden agarose gels which are stamped on polyacrylamide films containing immobilized substrates and reversible inhibitors. Quantitative fluorescence imaging combined with detailed numerical simulations of the reaction-diffusion process reveal that a shallow gradient of enzyme is converted into a steep product gradient by addition of strong inhibitors, consistent with a mathematical model of molecular titration. The results confirm that ultrasensitive and threshold effects at the molecular level can convert a graded input signal to a steep spatial response at macroscopic length scales. PMID:23972857

Semenov, Sergey N; Markvoort, Albert J; Gevers, Wouter B L; Piruska, Aigars; de Greef, Tom F A; Huck, Wilhelm T S

2013-08-20

251

Isothermal titration calorimetry of ion-coupled membrane transporters.  

PubMed

Binding of ligands, ranging from proteins to ions, to membrane proteins is associated with absorption or release of heat that can be detected by isothermal titration calorimetry (ITC). Such measurements not only provide binding affinities but also afford direct access to thermodynamic parameters of binding - enthalpy, entropy and heat capacity. These parameters can be interpreted in a structural context, allow discrimination between different binding mechanisms and guide drug design. In this review, we introduce advantages and limitations of ITC as a methodology to study molecular interactions of membrane proteins. We further describe case studies where ITC was used to analyze thermodynamic linkage between ions and substrates in ion-coupled transporters. Similar type of linkage analysis will likely be applicable to a wide range of transporters, channels, and receptors. PMID:25676707

Boudker, Olga; Oh, SeCheol

2015-04-01

252

Neurons limit angiogenesis by titrating VEGF in retina.  

PubMed

Vascular and nervous systems, two major networks in mammalian bodies, show a high degree of anatomical parallelism and functional crosstalk. During development, neurons guide and attract blood vessels, and consequently this parallelism is established. Here, we identified a noncanonical neurovascular interaction in eye development and disease. VEGFR2, a critical endothelial receptor for VEGF, was more abundantly expressed in retinal neurons than in endothelial cells, including endothelial tip cells. Genetic deletion of VEGFR2 in neurons caused misdirected angiogenesis toward neurons, resulting in abnormally increased vascular density around neurons. Further genetic experiments revealed that this misdirected angiogenesis was attributable to an excessive amount of VEGF protein around neurons caused by insufficient engulfment of VEGF by VEGFR2-deficient neurons. Moreover, absence of neuronal VEGFR2 caused misdirected regenerative angiogenesis in ischemic retinopathy. Thus, this study revealed neurovascular crosstalk and unprecedented cellular regulation of VEGF: retinal neurons titrate VEGF to limit neuronal vascularization. PAPERFLICK: PMID:25417109

Okabe, Keisuke; Kobayashi, Sakiko; Yamada, Toru; Kurihara, Toshihide; Tai-Nagara, Ikue; Miyamoto, Takeshi; Mukouyama, Yoh-suke; Sato, Thomas N; Suda, Toshio; Ema, Masatsugu; Kubota, Yoshiaki

2014-10-23

253

Ultrasensitivity by Molecular Titration in Spatially Propagating Enzymatic Reactions  

PubMed Central

Delineating design principles of biological systems by reconstitution of purified components offers a platform to gauge the influence of critical physicochemical parameters on minimal biological systems of reduced complexity. Here we unravel the effect of strong reversible inhibitors on the spatiotemporal propagation of enzymatic reactions in a confined environment in vitro. We use micropatterned, enzyme-laden agarose gels which are stamped on polyacrylamide films containing immobilized substrates and reversible inhibitors. Quantitative fluorescence imaging combined with detailed numerical simulations of the reaction-diffusion process reveal that a shallow gradient of enzyme is converted into a steep product gradient by addition of strong inhibitors, consistent with a mathematical model of molecular titration. The results confirm that ultrasensitive and threshold effects at the molecular level can convert a graded input signal to a steep spatial response at macroscopic length scales. PMID:23972857

Semenov, Sergey N.; Markvoort, Albert J.; Gevers, Wouter B.L.; Piruska, Aigars; de Greef, Tom F.A.; Huck, Wilhelm T.S.

2013-01-01

254

Development and certification of an automated differential titration photocalorimeter  

NASA Astrophysics Data System (ADS)

An automated differential titration photocalorimeter (ADTPC) has been designed for investigating photoinduced processes. This instrument provides means to record thermal and spectral (absorbance) changes in a calorimetric cell. Metrological characteristics of the described ADTPC are detection limit, 0.001 J with a reproducibility of 0.0002 J or better; short-duration noise level, ±5 rel. units; long-duration noise level, ±29 rel. units. ADTPC has been certified against the heats of mixing of solvents and the heat of neutralization reaction between tris(hydroxymethyl)aminomethane and HCl. The photocalorimetric unit of the device has additionally been certified against the heat of photolysis of K3[Fe(C2O4)3] and the heat of isomerization of azobenzene in heptane. Within the claimed errors, the heats measured with ADTPC are in agreement with the values recommended for the above systems.

Gubarev, Yu. A.; Lebedeva, N. Sh.; V'yugin, A. I.; Golubev, S. N.

2015-04-01

255

Photometric Covariance in Multi-Band Surveys: Understanding the Photometric Error in the SDSS  

E-print Network

In this paper we describe a detailed analysis of the photometric uncertainties present within the Sloan Digital Sky Survey (SDSS) imaging survey based on repeat observations of approximately 200 square degrees of the sky. We show that, for the standard SDSS aperture systems (petrocounts, counts_model, psfcounts and cmodel_counts), the errors generated by the SDSS photometric pipeline under-estimate the observed scatter in the individual bands. The degree of disagreement is a strong function of aperture and magnitude (ranging from 20% to more than a factor of 2). We also find that the photometry in the five optical bands can be highly correlated for both point sources and galaxies, although the correlation for point sources is almost entirely due to variable objects. Without correcting for this covariance the SDSS color errors could be in over-estimated by a factor of two to three. Combining these opposing effects, the SDSS errors on the colors differ from the observed color variation by approximately 10-20% for most apertures and magnitudes. We provide a prescription to correct the errors derived from the SDSS photometric pipeline as a function of magnitude and a semi-analytic method for generating the appropriate covariance between the different photometric passbands. Given the intrinsic nature of these correlations, we expect that all current and future multi-band surveys will also observe strongly covariant magnitudes. The ability of these surveys to complete their science goals is largely dependent on color-based target selection and photometric redshifts; these results show the importance of spending a significant fraction of early survey operations on re-imaging to empirically determine the photometric covariance of any observing/reduction pipeline.

Ryan Scranton; Andrew J. Connolly; Alexander S. Szalay; Robert H. Lupton; David Johnston; Tamas Budavari; John Brinkman; Masataka Fukugita

2005-09-16

256

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

1997-01-01

257

Acid–Base Titration: Analysis of Phosphoric Acid Anodizing Solutions. A Problem-Based Learning Approach  

Microsoft Academic Search

Phosphoric acid anodizing solutions are routinely titrated to monitor their concentrations; however, after successive anodizations of aluminum metal, increasing amounts of dissolved aluminum interfere with the neutralization titration. The true concentration of phosphoric acid is determined by a correction factor based on the concentration of the dissolved aluminum, which is determined industrially by flame atomic absorption spectrometry. The academic determination

Marina C. Koether; Charles R. Munafo

2002-01-01

258

A knowledge based advisory system for acid\\/base titrations in non-aqueous solvents  

Microsoft Academic Search

A computer program was developed that could advice on the choice of solvent and titrant for acid\\/base titrations in nonaqueous media. It is shown that the feasibility of a titration in a given solvent can be calculated from solvent properties and intrinsic acid\\/base properties of the sample components. A consistent set of properties for various solvents and a large number

M. Bos; W. E. van der Linden

1996-01-01

259

A Laser-Pointer-Based Spectrometer for Endpoint Detection of EDTA Titrations  

ERIC Educational Resources Information Center

A laser spectrometer for the ethylenediaminetetra-acetic acid (EDTA) titration of magnesium or calcium ions that is designed around a handheld laser pointer as the source and a photoresistor as the detector is developed. Findings show that the use of the spectrometer reduces the degree of uncertainty and error in one part of the EDTA titrations,…

Dahm, Christopher E.; Hall, James W.; Mattioni, Brian E.

2004-01-01

260

An Isothermal Titration Calorimetric Method to Determine the Kinetic Parameters of Enzyme Catalytic Reaction  

E-print Network

of enzyme. The molar reaction heat was calculated from the titration peak area divided by substrate moles per titration, and the initial catalytic reaction rate in the presence of vari- ous concentrations of product can be calculated from the peak height and the molar reaction heat. From Michaelis­Menten function

Luhua, Lai

261

Using RNA sample titrations to assess microarray platform performance and normalization techniques  

Microsoft Academic Search

We have assessed the utility of RNA titration samples for evaluating microarray platform performance and the impact of different normalization methods on the results obtained. As part of the MicroArray Quality Control project, we investigated the performance of five commercial microarray platforms using two independent RNA samples and two titration mixtures of these samples. Focusing on 12,091 genes common across

Stephanie Fulmer-Smentek; Roderick V Jensen; Wendell D Jones; Paul K Wolber; Charles D Johnson; P Scott Pine; Cecilie Boysen; Xu Guo; Eugene Chudin; Yongming Andrew Sun; James C Willey; Jean Thierry-Mieg; Danielle Thierry-Mieg; Robert A Setterquist; Mike Wilson; Anne Bergstrom Lucas; Natalia Novoradovskaya; Adam Papallo; Yaron Turpaz; Shawn C Baker; Janet A Warrington; Leming Shi; Damir Herman; Richard Shippy

2006-01-01

262

Entropic Effects and Slow Kinetics Revealed in Titrations of D2O-H2O Solutions with Different D/H Ratios  

E-print Network

Entropic Effects and Slow Kinetics Revealed in Titrations of D2O-H2O Solutions with Different D titration calorimetry (ITC) to investigate the enthalpy of titration of D2O-H2O solutions with different D to the computed enthalpy for the limit of ideal mixing both for dilution titration and for concentration titration

Jacob, Eshel Ben

263

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.

1992-01-01

264

Photometric study of eclipsing binary RV Tri  

E-print Network

We present new photometric observations of RV Tri. A complete light curve was obtained in the R and V filters. These light curves were processed by the Wilson-Devinney (WD) code and the FOTEL to get solution of this eclipsing binary system. We discuss characteristics of the system and compare our model with a previous calculation. Our observations of primary minima and the comparison with those predicted on the base of the GCVS catalogue indicates that there are significant differences. We discuss these differences in the context of period change.

F. Hroch; M. Basny

2002-02-21

265

Atmospheric Emissions Photometric Imaging (AEPI) experiment  

NASA Technical Reports Server (NTRS)

Space plasma physics will be studied on the Atmospheric Laboratory for Applications and Science (ATLAS 1) NASA mission during the Atmospheric Emissions Photometric Imaging (AEPI) experiment. The basic scientific objective of the AEPI is the investigation of the upper atmosphere-ionosphere and the space shuttle environment. The experiment areas of the AEPI include: (1) the investigation of ionospheric transport processes by observing Mg(+) ions; (2) studies of optical properties of artificially induced electron beams; (3) measurement of electron cross sections for selected atmospheric species; (4) studies of natural airglow; and (5) studies of natural auroras. On ATLAS 1, optical emissions generated by the shuttle (shuttle ram glow) will also be investigated.

Mende, S. B.

1988-01-01

266

Potentiometric titration of sulfate with lead and barium ions with various indicating electrodes  

SciTech Connect

Several types of graphite were used as sensors in the potentiometric titration of 25 to 75 ..mu..mol of sulfate vs. lead(II) and barium(II) and compared with titrations obtained with a lead ion-selective electrode (ISE). Pyrolytic graphite and high-density graphite, conditioned in neutral potassium permanganate, were found to be good alternatives to the lead ISE. A qualitative study was made of a variety of commercially available ISE's and other materials as sensors in the titration of 5 ..mu..mol of sulfate vs lead(II). Every ISE and conducting material tested yielded a usable response. While that of the commonly used lead ISE was largest, some other ISE's and metal rods also function satisfactorily as sensors in this titration. All titrations were carried out in a partially nonaqueous medium, which is required even for the lead ISE at the low sulfate levels investigated. 18 references, 4 figures, 5 tables.

Selig, W.S.

1984-01-01

267

Nonaqueous potentiometric titration and elemental analysis of high-boiling distillates of Saudi Arabian crude oils  

SciTech Connect

Nonaqueous potentiometric titration and elemental analysis were used to study basic and nonbasic functionalities present in high-boiling distillates of four Saudi Arabian crude oils. Model nitrogen compounds were titrated under similar titration conditions to differentiate them into strong, weak and nonbasic species. The strong bses titrated were due to the presence of of pyridine and its benzologs like acridines, phenanthridines and quionolines. The weak bases titrated were due to phenazxines and amides whereas the pyrroles, indoles and carbazoles were found to be nonbasic in nature. The total nitrogen and the total basic nitrogen compounds were generally found to be in very low concentration in the four crude oil distillates. A gradual decrease in the basicity of the distillates was found from Arab Heavy to Arab Extra Light through Arab Medium and Arab Light crude oils.

Ali, M.F.; Ali, M.A. (Dept. of Chemistry, King Fahd Univ. of Petroleum and Minerals, Dhahran 31261 (SA))

1988-12-01

268

Determination of vanadium(V) by direct automatic potentiometric titration with EDTA using a chemically modified electrode as a potentiometric sensor.  

PubMed

A chemically modified electrode (CME) was prepared and studied as a potentiometric sensor for the end-point detection in the automatic titration of vanadium(V) with EDTA. The CME was constructed with a paste prepared by mixing spectral-grade graphite powder, Nujol oil and N-2-naphthoyl-N-p-tolylhydroxamic acid (NTHA). Buffer systems, pH effects and the concentration range were studied. Interference ions were separated by applying a liquid-liquid extraction procedure. The CME did not require any special conditioning before using. The electrode was constructed with very inexpensive materials and was easily made. It could be continuously used, at least two months without removing the paste. Automatic potentiometric titration curves were obtained for V(V) within 5 x 10(-5) to 2 x 10(-3)M with acceptable accuracy and precision. The developed method was applied to V(V) determination in alloys for hip prosthesis. PMID:18970248

Quintar, S E; Santagata, J P; Cortinez, V A

2005-10-15

269

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

2013-01-01

270

Simultaneous Estimation of Photometric Redshifts and SED Parameters: Improved Techniques and a Realistic Error Budget  

E-print Network

We seek to improve the accuracy of joint galaxy photometric redshift estimation and spectral energy distribution (SED) fitting. By simulating different sources of uncorrected systematic errors, we demonstrate that if the uncertainties on the photometric redshifts are estimated correctly, so are those on the other SED fitting parameters, such as stellar mass, stellar age, and dust reddening. Furthermore, we find that if the redshift uncertainties are over(under)-estimated, the uncertainties in SED parameters tend to be over(under)-estimated by similar amounts. These results hold even in the presence of severe systematics and provide, for the first time, a mechanism to validate the uncertainties on these parameters via comparison with spectroscopic redshifts. We propose a new technique (annealing) to re-calibrate the joint uncertainties in the photo-z and SED fitting parameters without compromising the performance of the SED fitting + photo-z estimation. This procedure provides a consistent estimation of the mu...

Acquaviva, Viviana; Gawiser, Eric

2015-01-01

271

Photometric Analysis Of Sn2011dn  

NASA Astrophysics Data System (ADS)

Type Ia supernovae (SNe Ia) have been extensively studied and used as standard candles. There are different sub types of SNe Ia, that include over-luminous (SN 1991T-like), under-luminous (SN 1991bg-like), and peculiar (e.g., SN2000cx, SN 2002cx, SN 2005hk). These sub-types reveal themselves through spectral and photometric differences from "normal" SNe Ia. Here we report on the collection and reduction of photometric data of supernova SN 2011dn during the course of a 41 day period, which started a few days before maximum. A pre-maximum spectrum provided a tentative SN 1991T-like classification (Koff et al. 2011) for this event, from which a broad, slowly declining light-curve with low Delta M_15(B) was anticipated. However, preliminary reduction (i.e., without the benefit of galaxy subtraction) and analysis of our light curves suggest that SN 2011dn did not confirm this prediction. In this poster we will discuss the peculiar nature of SN2011dn and compare it to other SNe Ia that have exhibited similar characteristics. We acknowledge support from the National Science Foundation (grants AST-1009571 and AST-0850564) under which this work was carried out.

Salvo, Christopher; Leonard, D. C.; Sumandal, J.; Horst, C.

2012-01-01

272

Photometric redshifts in the SWIRE Survey  

NASA Astrophysics Data System (ADS)

We present the SWIRE Photometric Redshift Catalogue 1025119 redshifts of unprecedented reliability and of accuracy comparable with or better than previous work. Our methodology is based on fixed galaxy and quasi-stellar object templates applied to data at 0.36-4.5 ?m, and on a set of four infrared emission templates fitted to infrared excess data at 3.6-170 ?m. The galaxy templates are initially empirical, but are given greater physical validity by fitting star formation histories to them, which also allows us to estimate stellar masses. The code involves two passes through the data, to try to optimize recognition of active galactic nucleus (AGN) dust tori. A few carefully justified priors are used and are the key to supression of outliers. Extinction, AV, is allowed as a free parameter. The full reduced ?2? (z) distribution is given for each source, so the full error distribution can be used, and aliases investigated. We use a set of 5982 spectroscopic redshifts, taken from the literature and from our own spectroscopic surveys, to analyse the performance of our method as a function of the number of photometric bands used in the solution and the reduced ?2?. For seven photometric bands (5 optical + 3.6, 4.5 ?m), the rms value of (zphot - zspec)/(1 + zspec) is 3.5 per cent, and the percentage of catastrophic outliers [defined as >15 per cent error in (1 + z)], is ~1 per cent. These rms values are comparable with the best achieved in other studies, and the outlier fraction is significantly better. The inclusion of the 3.6- and 4.5-?m IRAC bands is crucial in supression of outliers. We discuss the redshift distributions at 3.6 and 24 ?m. In individual fields, structure in the redshift distribution corresponds to clusters which can be seen in the spectroscopic redshift distribution, so the photometric redshifts are a powerful tool for large-scale structure studies. 10 per cent of sources in the SWIRE photometric redshift catalogue have z > 2, and 4 per cent have z > 3, so this catalogue is a huge resource for high-redshift galaxies. A key parameter for understanding the evolutionary status of infrared galaxies is Lir/Lopt. For cirrus galaxies this is a measure of the mean extinction in the interstellar medium of the galaxy. There is a population of ultraluminous galaxies with cool dust and we have shown SEDs for some of the reliable examples. For starbursts, we estimate the specific star formation rate, ?*/M*. Although the very highest values of this ratio tend to be associated with Arp220 starbursts, by no means all ultraluminous galaxies are. We discuss an interesting population of galaxies with elliptical-like spectral energy distributions in the optical and luminous starbursts in the infrared. For dust tori around type 1 AGN, Ltor/Lopt is a measure of the torus covering factor and we deduce a mean covering factor of 40 per cent. Our infrared templates also allow us to estimate dust masses for all galaxies with an infrared excess.

Rowan-Robinson, Michael; Babbedge, Tom; Oliver, Seb; Trichas, Markos; Berta, Stefano; Lonsdale, Carol; Smith, Gene; Shupe, David; Surace, Jason; Arnouts, Stephane; Ilbert, Olivier; Le Févre, Olivier; Afonso-Luis, Alejandro; Perez-Fournon, Ismael; Hatziminaoglou, Evanthia; Polletta, Mari; Farrah, Duncan; Vaccari, Mattia

2008-05-01

273

Misuse of thermodynamics in the interpretation of isothermal titration calorimetry data for ligand binding to proteins.  

PubMed

Isothermal titration calorimetry (ITC) has given a mass of data on the binding of small molecules to proteins and other biopolymers, with particular interest in drug binding to proteins chosen as therapeutic indicators. Interpretation of the enthalpy data usually follows an unsound protocol that uses thermodynamic relations in circumstances where they do not apply. Errors of interpretation include incomplete definitions of ligand binding and equilibrium constants and neglect of the non-ideality of the solutions under study, leading to unreliable estimates of standard free energies and entropies of binding. The mass of reported thermodynamic functions for ligand binding to proteins estimated from ITC enthalpies alone is consequently of uncertain thermodynamic significance and utility. ITC and related experiments to test the protocol assumptions are indicated. A thermodynamic procedure avoiding equilibrium constants or other reaction models and not requiring protein activities is given. The discussion draws attention to the fundamental but neglected relation between the thermodynamic activity and bioactivity of drugs and to the generally unknown thermodynamic status of ligand solutions, which for drugs relates directly to effective therapeutic dosimetry. PMID:25484232

Pethica, Brian A

2015-03-01

274

Apparent Cooperative Assembly of the Bacterial Cell Division Protein FtsZ Demonstrated by Isothermal Titration Calorimetry*  

E-print Network

by Isothermal Titration Calorimetry* Received for publication, January 27, 2003 Published, JBC Papers in Press isothermal titration calorim- etry (ITC) to measure the heat of FtsZ self-association under various

Erickson, Harold P.

275

Volume 177, number 2 CHEMICAL PHYSICS LETTERS 15 February 1991 Cu titration of tilted CO on a MO( 110) surface  

E-print Network

Volume 177, number 2 CHEMICAL PHYSICS LETTERS 15 February 1991 Cu titration of tilted CO on a MO-reflection-ab- sorption-spectroscopy (IRAS), Auger electron spec- troscopy (AES), as well as Cu titration. As will be seen

Goodman, Wayne

276

Structures of Prolyl Oligopeptidase Substrate/Inhibitor Complexes USE OF INHIBITOR BINDING FOR TITRATION OF THE CATALYTIC HISTIDINE RESIDUE*  

E-print Network

FOR TITRATION OF THE CATALYTIC HISTIDINE RESIDUE* Received for publication, August 3, 2000, and in revised form- teases. The new titration method gave a single pKa for prolyl oligopeptidase, whose reaction exhibited

Fülöp, Vilmos

277

Binding isotherms for soluble immobilized affinity ligands from spectral titration.  

PubMed

The method of spectral titration has been applied to binding equilibria between proteins and soluble immobilized ligands and evaluated using the interaction between Cibacron blue-dextran conjugates and lysozyme. The method is both simple and rapid and provides a convenient screening technique for characterization of soluble adsorbents designed for use in aqueous two-phase affinity extraction or as liquid-phase models for affinity chromatography systems. The results indicate that regardless of ligand density a constant 28% of the total coupled dye is available for high-affinity protein binding at saturation. The dissociation constant for the dye-protein interaction, however, decreases with dye loading. The potential for kinetic investigations has been demonstrated using a stopped-flow apparatus. The results indicate that a simple rate equation is inadequate to describe the data for lysozyme binding to dye-dextran conjugates. A modified model, which better describes the data, was developed by including a second rate limiting process, the transition from stacked to unstacked dye ligands on the dextran backbone. This effect could have practical significance for protein binding kinetics in affinity chromatography, especially in high-performance liquid affinity chromatography applications where mass transfer is rapid. PMID:18601078

Mayes, A G; Eisenthal, R; Hubble, J

1992-12-01

278

Application of isothermal titration calorimetry in bioinorganic chemistry.  

PubMed

The thermodynamics of metals ions binding to proteins and other biological molecules can be measured with isothermal titration calorimetry (ITC), which quantifies the binding enthalpy (?H°) and generates a binding isotherm. A fit of the isotherm provides the binding constant (K), thereby allowing the free energy (?G°) and ultimately the entropy (?S°) of binding to be determined. The temperature dependence of ?H° can then provide the change in heat capacity (?C (p)°) upon binding. However, ITC measurements of metal binding can be compromised by undesired reactions (e.g., precipitation, hydrolysis, and redox), and generally involve competing equilibria with the buffer and protons, which contribute to the experimental values (K (ITC), ?H (ITC)). Guidelines and factors that need to be considered for ITC measurements involving metal ions are outlined. A general analysis of the experimental ITC values that accounts for the contributions of metal-buffer speciation and proton competition and provides condition-independent thermodynamic values (K, ?H°) for metal binding is developed and validated. PMID:20725755

Grossoehme, Nicholas E; Spuches, Anne M; Wilcox, Dean E

2010-11-01

279

Hot biological catalysis: isothermal titration calorimetry to characterize enzymatic reactions.  

PubMed

Isothermal titration calorimetry (ITC) is a well-described technique that measures the heat released or absorbed during a chemical reaction, using it as an intrinsic probe to characterize virtually every chemical process. Nowadays, this technique is extensively applied to determine thermodynamic parameters of biomolecular binding equilibria. In addition, ITC has been demonstrated to be able of directly measuring kinetics and thermodynamic parameters (kcat, KM, ?H) of enzymatic reactions, even though this application is still underexploited. As heat changes spontaneously occur during enzymatic catalysis, ITC does not require any modification or labeling of the system under analysis and can be performed in solution. Moreover, the method needs little amount of material. These properties make ITC an invaluable, powerful and unique tool to study enzyme kinetics in several applications, such as, for example, drug discovery. In this work an experimental ITC-based method to quantify kinetics and thermodynamics of enzymatic reactions is thoroughly described. This method is applied to determine kcat and KM of the enzymatic hydrolysis of urea by Canavalia ensiformis (jack bean) urease. Calculation of intrinsic molar enthalpy (?Hint) of the reaction is performed. The values thus obtained are consistent with previous data reported in literature, demonstrating the reliability of the methodology. PMID:24747990

Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

2014-01-01

280

Colorimetric nanoplasmonic assay to determine purity and titrate extracellular vesicles.  

PubMed

Extracellular Vesicles (EVs) - cell secreted vesicles that carry rich molecular information of the parental cell and constitute an important mode of intercellular communication - are becoming a primary topic in translational medicine. EVs (that comprise exosomes and microvesicles/microparticles) have a size ranging from 40 nm to 1 ?m and share several physicochemical proprieties, including size, density, surface charge, and light interaction, with other nano-objects present in body fluids, such as single and aggregated proteins. This makes separation, titration, and characterization of EVs challenging and time-consuming. Here we present a cost-effective and fast colorimetric assay for probing by eye protein contaminants and determine the concentration of EV preparations, which exploits the synergy between colloidal gold nanoplasmonics, nanoparticle-protein corona, and nanoparticle-membrane interaction. The assay hits a limit of detection of protein contaminants of 5 ng/?L and has a dynamic range of EV concentration ranging from 35 fM to 35 pM, which matches the typical range of EV concentration in body fluids. This work provides the first example of the exploitation of the nanoparticle-protein corona in analytical chemistry. PMID:25674701

Maiolo, Daniele; Paolini, Lucia; Di Noto, Giuseppe; Zendrini, Andrea; Berti, Debora; Bergese, Paolo; Ricotta, Doris

2015-04-21

281

Probing lectin-mucin interactions by isothermal titration microcalorimetry.  

PubMed

Isothermal titration microcalorimetry (ITC) can directly determine the thermodynamic binding parameters of biological molecules including affinity constant, binding stoichiometry, and heat of binding (enthalpy) and indirectly the entropy and free energy of binding. ITC has been extensively used to study the binding of lectins to mono- and oligosaccharides, but limited applications to lectin-glycoprotein interactions. Inherent experimental challenges to ITC include sample precipitation during the experiment and relative high amount of sample required, but careful design of experiments can minimize these problems and allow valuable information to be obtained. For example, the thermodynamics of binding of lectins to multivalent globular and linear glycoproteins (mucins) have been described. The results are consistent with a dynamic binding mechanism in which lectins bind and jump from carbohydrate to carbohydrate epitope in these molecules leading to increased affinity. Importantly, the mechanism of binding of lectins to mucins appears similar to that for a variety of protein ligands binding to DNA. Recent results also show that high affinity lectin-mucin cross-linking interactions are driven by favorable entropy of binding that is associated with the bind and jump mechanism. The results suggest that the binding of ligands to biopolymers, in general, may involve a common mechanism that involves enhanced entropic effects that facilitate binding interactions. PMID:25253134

Dam, Tarun K; Brewer, C Fred

2015-01-01

282

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.

2014-08-01

283

Enzyme kinetics determined by single-injection isothermal titration calorimetry.  

PubMed

The purposes of this paper are (a) to examine the effect of calorimeter time constant (?) on heat rate data from a single enzyme injection into substrate in an isothermal titration calorimeter (ITC), (b) to provide information that can be used to predict the optimum experimental conditions for determining the rate constant (k2), Michaelis constant (KM), and enthalpy change of the reaction (?RH), and (c) to describe methods for evaluating these parameters. We find that KM, k2 and ?RH can be accurately estimated without correcting for the calorimeter time constant, ?, if (k2E/KM), where E is the total active enzyme concentration, is between 0.1/? and 1/? and the reaction goes to at least 99% completion. If experimental conditions are outside this domain and no correction is made for ?, errors in the inferred parameters quickly become unreasonable. A method for fitting single-injection data to the Michaelis-Menten or Briggs-Haldane model to simultaneously evaluate KM, k2, ?RH, and ? is described and validated with experimental data. All four of these parameters can be accurately inferred provided the reaction time constant (k2E/KM) is larger than 1/? and the data include enzyme saturated conditions. PMID:25497059

Transtrum, Mark K; Hansen, Lee D; Quinn, Colette

2015-04-01

284

On the virtue of acid–base titrations for the determination of basic sites in nitrogen doped carbon nanotubes  

Microsoft Academic Search

The basicity and nature of basic species in nitrogen containing carbon nanotubes (NCNT) prepared under different conditions were investigated by acid–base titrations. Proton uptake curves were derived from the titration data and were used to establish the basicity (pKa) ranges of nitrogen species present in NCNT. Based on the evolution of the titration curves upon acid addition the NCNT were

J. H. Bitter; S. van Dommele; K. P. de Jong

2010-01-01

285

Supplementary Material Figure S1: Result of combinatorial scan on the titration curves of Glu78 and Glu172  

E-print Network

Supplementary Material Figure S1: Result of combinatorial scan on the titration curves of Glu78: Global fit of NMR titration curves for FNfn10: Asp7: black curve, Glu9: blue curve, Asp23: red curve. NMR titration data is represented by dots. #12;Figure S4: Global fit of His12 (black curve) and His119 (blue

McIntosh, Lawrence P.

286

A Solution of the Dichromatic Model for Multispectral Photometric Invariance  

E-print Network

A Solution of the Dichromatic Model for Multispectral Photometric Invariance Cong Phuoc Huynh1 In this paper, we address the problem of photometric invariance in multispectral imaging making use study. The dichromatic parameters are recovered through minimising this cost function in a coor- dinate

Huynh, Cong Phuoc

287

Photometric and spectroscopic study of AZ Canis Minoris  

Microsoft Academic Search

Photometric and spectrographic observations of this Delta Sct variable are presented. A comparison of photometric data over a period of 17 years indicates the binary nature of this variable. A tentative period of seven years has been derived. Applying relations applicable to this group of stars, it has been shown that this variable is a giant star with a radius

Gustav A. Bakos; Jozef Tremko

1987-01-01

288

Empirical color transformations between SDSS photometry and other photometric systems  

Microsoft Academic Search

Aims.We present empirical color transformations between the Sloan Digital Sky Survey (SDSS) ugriz photometry and the Johnson-Cousins UBVRI system and Becker's RGU system, respectively. Owing to the magnitude of data that is becoming available in the SDSS photometric system it is particularly important to be able to convert between this new system and traditional photometric systems. Unlike earlier published transformations

Katrin Jordi; E. K. Grebel; Karin Ammon

2006-01-01

289

Comparison of methods for accurate end-point detection of potentiometric titrations  

NASA Astrophysics Data System (ADS)

Detection of the end point in potentiometric titrations has wide application on experiments that demand very low measurement uncertainties mainly for certifying reference materials. Simulations of experimental coulometric titration data and consequential error analysis of the end-point values were conducted using a programming code. These simulations revealed that the Levenberg-Marquardt method is in general more accurate than the traditional second derivative technique used currently as end-point detection for potentiometric titrations. Performance of the methods will be compared and presented in this paper.

Villela, R. L. A.; Borges, P. P.; Vysko?il, L.

2015-01-01

290

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

E-print Network

are serried out bp setting the oscillator at one of these optimum frequencies ~ This fre- quenop is held oonstent Chroughout the titration. The end-point is shown bp an abrupt shape in the output of ths osoillator, This msp be produosd in several wars... disaypssrsnoe at ths end-point senses the ohange in the output. Titrations msp be serried out at frequenoies showing small differ- ences in absorption between the substanoes involved in the titration. Eowever at suoh frequenoies the sn4-point is mush less...

Griffin, James Hilton

1940-01-01

291

Ionic equilibria in neutral amphiprotic solvents of low dielectric constant: Titration curves.  

PubMed

Titration curves have been simulated for the titration of acids, bases and salts in neutral amphiprotic solvents such as isopropyl and tert-butyl alcohols. Ranges of pK values and acid concentrations have been examined. The incomplete dissociation of salts, which increases the acid or basic strength, has been found to be the major factor modifying the shape of the curve and the pH break. The theoretical predictions have been checked by titrating several series of acids and good agreement has been obtained between computed and experimental results. PMID:18964769

Bosch, E; Rosés, M

1989-06-01

292

Measuring magnification bias in photometric galaxy surveys  

NASA Astrophysics Data System (ADS)

In this contribution, we analyze how cosmic magnification may be detected in upcoming large photometric galaxy surveys and how some systematic effects can affect it. Magnification manifests itself as an enhancement or decrease of galaxy/quasar number counts at very high redshifts due to the magnifying weak lensing effect of intervening matter in the line of sight. It usually shows up in observations as a correlation or anti-correlation at low angular scales in the cross-correlation function. Its amplitude is directly related to the galaxy bias and cosmological parameters. We focus on three particular systematics and we are carrying out this study in the context of the Dark Energy Survey (DES) that will cover 5000 square degrees and reach i_{AB}<24 making measurements up to z?1.4 with a photo-z resolution of 0.03(1+z).

Ponce, R.; Sánchez, E.; Sevilla, I.

2013-05-01

293

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

2014-05-01

294

Photometric observations of the Baptistina asteroid family  

NASA Astrophysics Data System (ADS)

The Baptistina family is one of the typical young asteroid families with an age estimated to be about 140-320 Myrs old [1]; considered to have not enough time to experience a significant collisional and dynamical evolution since it was formed. Therefore, it may offer a unique insight into spin rate distribution of relatively fresh fragments and physical mechanism of a family break-up event. We carried out time series photometric observations for the family members to obtain their physical properties, including sizes, shapes, rotational periods, spin axes, colors, and H-G parameters based on near round- theclock observations, using several 0.5-2 meter class telescopes. This study is expected to find some important clues on the collisional history and transport mechanism of the members from the resonance region in the Main-belt to the near Earth space.

Kim, M.-J.

2014-04-01

295

Time-Series Photometric Surveys: Some Musings  

NASA Astrophysics Data System (ADS)

We live in the era of large astronomical surveys aimed at collecting high photometric precision, high time resolution, and long term (near) continuous observations. Such surveys discover many variable sources and their study has led to new paradigms in observational astronomy. Periodic variables have a long and venerable history in astronomy being highly useful as distance ladders, to investigate stellar interior physics and to map out Galactic structure. However, typically less than 10% of all variable sources are periodic and a detailed understanding of the majority of variables, the non-periodic sources, is lacking. What can we learn from non-periodic variables? Are there alternative techniques or types of study that may help elucidate their true nature? This talk will attempt to provide a short review of our understanding of variable sources and provide some suggestions for a methodology toward the study of non-variable astronomical sources.

Howell, S. B.

296

Photometric Properties of Enceladus' South Polar Terrain  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

297

Some Tungsten Oxidation-Reduction Chemistry: A Paint Pot Titration.  

ERIC Educational Resources Information Center

Reports an oxidation-reduction experiment using tungsten, somewhat analogous to the classical student experiment involving oxidation-reduction of vanadium. Includes experimental procedures, results, and toxicity/cost of tungsten compounds. (Author/JN)

Pickering, Miles; Monts, David L.

1982-01-01

298

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

2014-09-01

299

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

2014-01-01

300

New approach in the treatment of data from an acid-base potentiometric titrationI. Monocomponent systems of monofunctional acids and bases.  

PubMed

Based on precise analysis of the acid-base equilibrium, a new approach in the treatment of experimental data from a potentiometric titration is proposed. A new general formula giving explicitly the relation V=f([H(+)]) is derived, valid for every acid-base titration, which includes mono- and polyfunctional protolytes and their mixtures. The present study is the first practical application of this formula for the simplest case, the analysis of one monofunctional protolyte. The collected mV data during the titration are converted into pH-values by means of an auto pH-calibration procedure, thus avoiding preliminary preparation of the measuring system. The mentioned pH-calibration method is applicable also in water-organic mixtures and allows the quantitative determination of sparingly soluble substances (particularly pharmaceuticals). The treatment of the data is performed by means of ready-to-use software products, which makes the proposed approach accessible for a wide range of applications. PMID:12560965

Maslarska, Vania; Tencheva, Jasmina; Budevsky, Omortag

2003-01-01

301

A note on the calculation of acid-base titration curves and their equivalence points.  

PubMed

An equation has been developed for the calculation of the titration curve of any mixture of acids and bases, and an alternative way of defining an equivalence point, suitable for computer calculations, is presented. PMID:18962361

Olin, A; Wallén, B

302

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

Code of Federal Regulations, 2010 CFR

...precipitated with barium chloride. Thiosulfate is not titrated under the conditions of the determination (Charlot, “Ann. chim, anal,”, 1945, 27, 153; Booth; “J. Soc. Leather Trades' Chemists,” 1956, 40, 238). Apparatus Burrette, 10...

2010-07-01

303

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

Code of Federal Regulations, 2012 CFR

...precipitated with barium chloride. Thiosulfate is not titrated under the conditions of the determination (Charlot, “Ann. chim, anal,”, 1945, 27, 153; Booth; “J. Soc. Leather Trades' Chemists,” 1956, 40, 238). Apparatus Burrette, 10...

2012-07-01

304

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

Code of Federal Regulations, 2011 CFR

...precipitated with barium chloride. Thiosulfate is not titrated under the conditions of the determination (Charlot, “Ann. chim, anal,”, 1945, 27, 153; Booth; “J. Soc. Leather Trades' Chemists,” 1956, 40, 238). Apparatus Burrette, 10...

2011-07-01

305

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

Code of Federal Regulations, 2013 CFR

...precipitated with barium chloride. Thiosulfate is not titrated under the conditions of the determination (Charlot, “Ann. chim, anal,”, 1945, 27, 153; Booth; “J. Soc. Leather Trades' Chemists,” 1956, 40, 238). Apparatus Burrette, 10...

2013-07-01

306

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

Code of Federal Regulations, 2014 CFR

...precipitated with barium chloride. Thiosulfate is not titrated under the conditions of the determination (Charlot, “Ann. chim, anal,”, 1945, 27, 153; Booth; “J. Soc. Leather Trades' Chemists,” 1956, 40, 238). Apparatus Burrette, 10...

2014-07-01

307

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

2007-01-01

308

A Computer-Based Simulation of an Acid-Base Titration  

ERIC Educational Resources Information Center

Reviews the advantages of computer simulated environments for experiments, referring in particular to acid-base titrations. Includes pre-lab instructions and a sample computer printout of a student's use of an acid-base simulation. Ten references. (PR)

Boblick, John M.

1971-01-01

309

Comparing the Titrations of Mixed-Acid Solutions Using Dropwise and Constant-Flow Techniques  

Microsoft Academic Search

A mixed-acid solution containing hydrochloric and phosphoric acids was used to determine the error associated with performing a real-time titration. The results were compared against those obtained by performing the titration in a more traditional dropwise addition of titrant near the equivalence points. It was found that the real-time techniques resulted in significantly decreased analysis times while maintaining a low

Paul Charlesworth; Matthew J. Seguin; David J. Chesney

2003-01-01

310

Potentiometric titrations in acetonitrile–water mixtures: evaluation of aqueous ionisation constant of ketoprofen  

Microsoft Academic Search

Non ideality of acetonitrile–water mixtures was studied from data on the excess of molar volumes and viscosities. pH and autoprotolisis constants were evaluated at the standard state of the mixed solvent from titrations of a strong acid with a strong base. In order to illustrate the evaluation of the aqueous ionisation constant of water insoluble compounds from pH titrations in

M. Ángeles Herrador; A. Gustavo González

2002-01-01

311

Arsenopyrite mineral based electrochemical sensor for acid–base titrations in ? -butyrolactone and propylene carbonate  

Microsoft Academic Search

\\u000a Abstract  A novel acid–base sensor based on the natural mineral arsenopyrite for titrations in ?-butyrolactone and propylene carbonate is validated and studied. This sensor, which requires only small sample volumes, was\\u000a employed for the titrations of some important organic acids (benzoic, anthranilic, and salicylic acid) with potassium hydroxide.\\u000a A stable stationary potential was attained at the arsenopyrite electrode in ?-butyrolactone and

Zorka Stani?; Jelena Stepanovi?; Zoran Simi?

312

Expressions of the general form of the acid-base titration curve  

Microsoft Academic Search

The titration of a multicomponent mixture can be described either with de Levie’s integral representation [1] or with Moisio’s\\u000a and Heikonen’s derivative representation [2]. In the latter method an experimental titration curve is numerically differentiated\\u000a and the computations are based on the buffer capacity. Numerical calculations demonstrate that the results of these two methods\\u000a coincide very well.

T. Moisio; M. Heikonen

1996-01-01

313

FIA acid–base titrations with a new flow-through pH detector  

Microsoft Academic Search

A pH-sensitive detector for flow-through potentiometry based on a graphite\\/quinhydrone composite electrode was applied for flow-injection analysis (FIA) titrations. Hydrochloric acid and acetic acid were titrated by injection of samples into a sodium hydroxide carrier solution. System conditions were optimised by variation of flow rate, injection volume and titrant concentration. The parameters sampling frequency, residence time and dispersion coefficient were

H. Kahlert; J. R. Pörksen; J. Behnert; F. Scholz

2005-01-01

314

Effects of cultivation conditions on acid–base titration properties of Shewanella putrefaciens  

Microsoft Academic Search

Acid–base titrations were conducted on pure strain laboratory cultures of the Gram-negative, facultatively aerobic bacterium Shewanella putrefaciens, cultivated under a range of conditions. Bacteria used in acid–base titrations were cultivated for periods of 24 to 100 h (exponential growth phase to late stationary phase), in varying media compositions (rich to minimal), and under aerobic and anaerobic conditions. In addition, two

Johnson R Haas

2004-01-01

315

Artificial neural networks applied to potentiometric acid–base flow injection titrations  

Microsoft Academic Search

Artificial neural network (ANN) was applied for data treatment as a multivariate calibration tool in a potentiometric acid–base flow injection titration. A multilayer feed-forward ANN model, with Levenberg–Marquardt weight error correction was used for data modeling. The neural network parameter architecture was optimized to establish a relationship between the titration profile and the acid concentration. Citric and malic acids in

Cleidiane G Zampronio; Jarbas J. R Rohwedder; Ronei J Poppi

2002-01-01

316

High school students' understanding of titrations and related acid- base phenomena  

Microsoft Academic Search

Acid-base titrations are common laboratory activities carried out in high school chemistry courses. Using a series of qualitative and computer-based tasks, this study examined sixteen American students' understanding of titrations. The findings indicated that students had considerable difficulty with acid-base chemistry, were unable to describe accurately acid-base concepts, such as pH, neutralization, strength, and the theoretical descriptions of acids and

Keith Sheppard

317

Unusual properties of crocodilian ovomacroglobulin shown in its methylamine treatment and sulfhydryl titration  

SciTech Connect

The inhibitory activity of chicken and crocodilian ovomacroglobulins against trypsin was measured before and after their incubation with methylamine. The result for crocodilian ovomacroglobulin showed that methylamine treatment destroyed half of its activity, in unique contrast to human alpha 2-macroglobulin and chicken ovomacroglobulin for which methylamine either destroys the inhibitory activity of the former completely or does not affect that of the latter at all. Free sulfhydryl groups of chicken and crocodilian ovomacroglobulins were titrated with 5,5'-dithiobis(2-nitrobenzoic acid) before and after incubation with trypsin. Prior to the incubation with trypsin the chicken and crocodilian proteins respectively had 0 and 1 titratable sulfhydryl per molecule of Mr 720,000. After treatment with trypsin the crocodilian protein had 3.5-4 titratable sulfhydryls, whereas there were no titratable sulfhydryls in the chicken protein. After denaturation of the crocodilian protein in sodium dodecyl sulfate at 100 degrees C the number of titratable sulfhydryls was 4. Chicken ovomacroglobulin again did not have an appreciable number of titratable sulfhydryls under similar denaturing conditions. Incubation of crocodilian protein with (14C)methylamine showed an incorporation of at least 2 mol of methylamine per molecule. The result indicated the presence of three intramolecular thiol ester bonds in crocodilian ovomacroglobulin with differential stability against external perturbations.

Arakawa, H.; Osada, T.; Ikai, A.

1986-02-01

318

Effects of ionic radius of redox-inactive bio-related metal ions on the radical-scavenging activity of flavonoids evaluated using photometric titration.  

PubMed

Mg(2+) enhanced the scavenging activity of (+)-catechin and quercetin against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH?), while Al(3+) decreased their activity. Such effects of Mg(2+) and Al(3+) were not observed for kaempferol. Na(+) and Ca(2+) with large ionic radii showed little effect on the DPPH?-scavenging activity of these three flavonoids. PMID:24030811

Waki, Tsukasa; Kobayashi, Shigeki; Matsumoto, Ken-ichiro; Ozawa, Toshihiko; Kamada, Tadashi; Nakanishi, Ikuo

2013-10-28

319

Voyager photometry of Triton - Haze and surface photometric properties  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

320

Rapid Titration of Measles and Other Viruses: Optimization with Determination of Replication Cycle Length  

PubMed Central

Background Measles virus (MV) is a member of the Paramyxoviridae family and an important human pathogen causing strong immunosuppression in affected individuals and a considerable number of deaths worldwide. Currently, measles is a re-emerging disease in developed countries. MV is usually quantified in infectious units as determined by limiting dilution and counting of plaque forming unit either directly (PFU method) or indirectly from random distribution in microwells (TCID50 method). Both methods are time-consuming (up to several days), cumbersome and, in the case of the PFU assay, possibly operator dependent. Methods/Findings A rapid, optimized, accurate, and reliable technique for titration of measles virus was developed based on the detection of virus infected cells by flow cytometry, single round of infection and titer calculation according to the Poisson's law. The kinetics follow up of the number of infected cells after infection with serial dilutions of a virus allowed estimation of the duration of the replication cycle, and consequently, the optimal infection time. The assay was set up to quantify measles virus, vesicular stomatitis virus (VSV), and human immunodeficiency virus type 1 (HIV-1) using antibody labeling of viral glycoprotein, virus encoded fluorescent reporter protein and an inducible fluorescent-reporter cell line, respectively. Conclusion Overall, performing the assay takes only 24–30 hours for MV strains, 12 hours for VSV, and 52 hours for HIV-1. The step-by-step procedure we have set up can be, in principle, applicable to accurately quantify any virus including lentiviral vectors, provided that a virus encoded gene product can be detected by flow cytometry. PMID:21915289

Grigorov, Boyan; Rabilloud, Jessica; Lawrence, Philip; Gerlier, Denis

2011-01-01

321

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.

2013-01-01

322

IMPROVED PHOTOMETRIC REDSHIFTS WITH SURFACE LUMINOSITY PRIORS  

SciTech Connect

We apply Bayesian statistics with prior probabilities of galaxy surface luminosity (SL) to improve photometric redshifts. We apply the method to a sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and South fields at 0.1 {approx}< z {approx}< 2.0. We start with spectrophotometric redshifts (SPZs) based on Probing Evolution and Reionization Spectroscopically grism spectra, which cover a wavelength range of 6000-9000 A, combined with (U)BViz(JHK) broadband photometry in the GOODS fields. The accuracy of SPZ redshifts is estimated to be {sigma}({delta}(z)) = 0.035 with an systematic offset of -0.026, where {delta}(z) = {delta}z/(1 + z), for galaxies in redshift range of 0.5 {approx}< z {approx}< 1.25. The addition of the SL prior probability helps break the degeneracy of SPZ redshifts between low redshift 4000 A break galaxies and high-redshift Lyman break galaxies which are mostly catastrophic outliers. For the 1138 galaxies at z {approx}< 1.6, the fraction of galaxies with redshift deviation {delta}(z)>0.2 is reduced from 15.0% to 10.4%, while the rms scatter of the fractional redshift error does not change much.

Xia Lifang; Cohen, Seth; Malhotra, Sangeeta; Rhoads, James; Grogin, Norman; Windhorst, Rogier A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Hathi, Nimish P. [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Pirzkal, Nor; Xu Chun [Space Telescope Science Institute, Baltimore, MD 21218 (United States)], E-mail: lifang.xia@asu.edu

2009-07-15

323

BROADBAND PHOTOMETRIC REVERBERATION MAPPING OF NGC 4395  

SciTech Connect

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

Edri, Haim; Rafter, Stephen E.; Kaspi, Shai; Behar, Ehud [Physics Department, the Technion, Haifa 32000 (Israel); Chelouche, Doron, E-mail: rafter@physics.technion.ac.il, E-mail: shai@physics.technion.ac.il, E-mail: behar@physics.technion.ac.il, E-mail: doron@sci.haifa.ac.il [Physics Department, Faculty of Natural Sciences, University of Haifa, Haifa (Israel)

2012-09-01

324

Improving color constancy by photometric edge weighting.  

PubMed

Edge-based color constancy methods make use of image derivatives to estimate the illuminant. However, different edge types exist in real-world images, such as material, shadow, and highlight edges. These different edge types may have a distinctive influence on the performance of the illuminant estimation. Therefore, in this paper, an extensive analysis is provided of different edge types on the performance of edge-based color constancy methods. First, an edge-based taxonomy is presented classifying edge types based on their photometric properties (e.g., material, shadow-geometry, and highlights). Then, a performance evaluation of edge-based color constancy is provided using these different edge types. From this performance evaluation, it is derived that specular and shadow edge types are more valuable than material edges for the estimation of the illuminant. To this end, the (iterative) weighted Gray-Edge algorithm is proposed in which these edge types are more emphasized for the estimation of the illuminant. Images that are recorded under controlled circumstances demonstrate that the proposed iterative weighted Gray-Edge algorithm based on highlights reduces the median angular error with approximately 25 percent. In an uncontrolled environment, improvements in angular error up to 11 percent are obtained with respect to regular edge-based color constancy. PMID:22442121

Gijsenij, Arjan; Gevers, Theo; van de Weijer, Joost

2012-05-01

325

Completion of the GOYA Photometric Survey  

NASA Astrophysics Data System (ADS)

The Galaxy Origins and Young Assembly (GOYA) survey is designed to study the formation and evolution of 1photometric survey, for sample selection and characterisation. Now that this research has reached its final stages, we report here on its current status and its finalisation plans. Overall, this survey has images of ˜ 0.5 square degrees of high-latitude sky to limiting AB magnitude Ks=23.7 (3-?, 1'' aperture) and corresponding depths at U, B, V, R, I and J. The sample of sources obtained is being extended to include fields available to Gemini-S, since a recent collaboration with the Flamingos-2 Early Science Survey Team grants GOYA privileged access to this pioneering near-infrared multi-object spectrograph.

Vallbe I Mumbrú, M.; Balcells, M.; Gallego, J.

2007-12-01

326

Determination of captopril in pharmaceutical tablets by anion-exchange HPLC using indirect photometric detection; a study in systematic method development  

Microsoft Academic Search

The development and validation of a significantly cost effective and simpler anion-exchange high performance liquid chromatorgaphic (HPLC) procedure than the compendial methods for the analysis of captopril in tablet dosage forms using indirect photometric detection is described. A low capacity anion-exchange column was used with potassium phthalate as the mobile phase marker and indirect detection at 280 nm. The chromatographic

Tahseen Mirza; Henry S. I Tan

2001-01-01

327

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

Water 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 by iodine in the presence of water. It is the same reaction as the iodometric titration of sulphur dioxide

Nazarenko, Alexander

328

Photometric Techniques for Exploring Multiple Populations in Clusters  

NASA Astrophysics Data System (ADS)

The advent of the Hubble Space Telescope (HST) and the development of new photometric algorithms that take advantage of its stable observing platform above the atmosphere have allowed us to study the populations in globular clusters with very high precision.

Anderson, Jay

2015-03-01

329

Flame photometric detector for thin-layer chromatography  

Microsoft Academic Search

A new flame photometric detector for thin-layer chromatography (TLC) was studied to determine sulfur and phosphorus containing compounds in materials with a high boiling point. The detector was integrated with a flame ionization detector into the Iatroscan TLC–flame ionization detection analyzer. The principle of the detector is based on the photometric detection of flame emission of heteroatom in a hydrogen–air

Minoru Ogasawara; Kyoko Tsuruta; Shinsuke Arao

2002-01-01

330

Photometric Observation And Period Study of GO Cygni  

E-print Network

Photometric observations of GO Cyg were performed during the July-October 2002, in B and V bands of Johnson system. Based on Wilson's model, the light curve analysis were carried out to find the photometric elements of the system. The O-C diagram which is based on new observed times of minima suggests a negative rate of period variation (dP/dt<0) for the system.

S. M. Zabihinpoor; A. Dariush; N. Riazi

2005-08-07

331

Photometric study of the active Algol system RZ Cassiopeiae  

Microsoft Academic Search

The active Algol binary system RZ Cas is studied photometrically. UBV light curves are analyzed with a light-curve synthesis method. The analysis yields a semidetached configuration, in which the more massive detached primary is eclipsed by the contact companion at the primary eclipse, i.e., RZ Cas is a usual semidetached Algol-type system. The photometric elements deduced indicate that the primary

Shin-Ya Narusawa; Yasuhisa Nakamura; Atsuma Yamasaki

1994-01-01

332

SuperNova Acceleration Probe (SNAP): Investigating Photometric Redshift Optimization  

E-print Network

The aim of this paper is to investigate ways to optimize the accuracy of photometric redshifts for a SNAP like mission. We focus on how the accuracy of the photometric redshifts depends on the magnitude limit and signal-to-noise ratio, wave-length coverage, number of filters and their shapes and observed galaxy type. We use simulated galaxy catalogs constructed to reproduce observed galaxy luminosity functions from GOODS, and derive photometric redshifts using a template fitting method. By using a catalog that resembles real data, we can estimate the expected number density of galaxies for which photometric redshifts can be derived. We find that the accuracy of photometric redshifts is strongly dependent on the signal-to-noise (S/N) (i.e., S/N>10 is needed for accurate photometric redshifts). The accuracy of the photometric redshifts is also dependent on galaxy type, with smaller scatter for earlier type galaxies. Comparing results using different filter sets, we find that including the U-band is important for decreasing the fraction of outliers, i.e., ``catastrophic failures''. Using broad overlapping filters with resolution ~4gives better photometric redshifts compared to narrower filters (resolution >~5) with the same integration time. We find that filters with square response curves result in a slightly higher scatter, mainly due to a higher fraction of outliers at faint magnitudes. We also compare a 9-filter set to a 17-filter set, where we assume that the available exposure time per filter in the latter set is half that of the first set. We find that the 9-filter set gives more accurate redshifts for a larger number of objects and reaches higher redshift, while the 17-filter set is gives better results at bright magnitudes.

Tomas Dahlen; Bahram Mobasher; Stephanie Jouvel; Jean-Paul Kneib; Olivier Ilbert; Stephane Arnouts; Gary Bernstein; Jason Rhodes

2007-10-29

333

Inferring solar structure variations from photometric and helioseismic observations  

NASA Technical Reports Server (NTRS)

Present large scale photometric and helioseismic data may be related to spatial and temporal deviations from an otherwise static, spherical solar convection zone (SCZ). New space experiments combine precise photometric, helioseismic, and magnetic observational capabilities (like SOHO and MDI) and will provide data needed to understand the interaction of magnetic fields and global scale circulation in the SCZ. Even simple physical arguments make it clear that the anticipated accuracy of these new experiments virtually guarantees new constraints on models of the SCZ.

Kuhn, J. R.

1991-01-01

334

Photometric observations of Rosetta target asteroid 2867 Steins  

E-print Network

Asteroid 2867 Steins is one of two flyby targets of ESAs international Rosetta mission, launched in March, 2004. We obtained photometric observations of Steins on April 14-16, 2004 at Table Mountain Observatory, California, in order to characterize the asteroid physically, information that is crucial for planning the Steins flyby. This study includes the first detailed analysis of the physical properties of Steins from time-series R-filter data along with V- and I-filter photometric measurements.

Paul R. Weissman; Stephen C. Lowry; Young-Jun Choi

2007-02-13

335

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

2013-04-01

336

The unusual photometric variability of the PMS star GM Cep  

E-print Network

Results from UBVRI photometric observations of the pre-main sequence star GM Cep obtained in the period April 2011 - August 2014 are reported in the paper. Presented data are a continuation of our photometric monitoring of the star started in 2008. GM Cep is located in the field of the young open cluster Trumpler 37 and over the past years it has been an object of intense photometric and spectral studies. The star shows a strong photometric variability interpreted as a possible outburst from EXor type in previous studies. Our photometric data for a period of over six years show a large amplitude variability (Delta V ~ 2.3 mag.) and several deep minimums in brightness are observed. The analysis of the collected multicolor photometric data shows the typical of UX Ori variables a color reversal during the minimums in brightness. The observed decreases in brightness have a different shape, and evidences of periodicity are not detected. At the same time, high amplitude rapid variations in brightness typical for th...

Semkov, E; Peneva, S; Milanov, T; Stoyanov, K; Stateva, I; Kjurkchieva, D; Dimitrov, D; Radeva, V

2015-01-01

337

The Unusual Photometric Variability of the PMS Star GM Cep  

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

338

Improved Photometric Calibrations for Red Stars Observed with the SDSS Photometric Telescope  

E-print Network

We present a new set of photometric transformations for red stars observed with the Sloan Digital Sky Survey (SDSS) 0.5-m Photometric Telescope (PT) and the SDSS 2.5-m telescope at the Apache Point Observatory in New Mexico. Nightly PT observations of US Naval Observatory standards are used to determine extinction corrections and calibration terms for SDSS 2.5-m photometry. Systematic differences between the PT and native SDSS 2.5-m {\\it ugriz} photometry require conversions between the two systems which have previously been undefined for the reddest stars. By matching $\\sim 43,000$ stars observed with both the PT and SDSS 2.5-m, we extend the present relations to include low-mass stars with colors $0.6 \\le r-i \\le 1.7$. These corrections will allow us to place photometry of bright, low-mass trigonometric parallax stars previously observed with the PT on the 2.5-m system. We present new transformation equations and discuss applications of these data to future low-mass star studies using the SDSS.

James R. A. Davenport; John J. Bochanski; Kevin R. Covey; Suzanne L. Hawley; Andrew A. West; Donald P. Schneider

2007-08-07

339

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.

2011-02-01

340

The Mobile Insulin Titration Intervention (MITI) for Insulin Glargine Titration in an Urban, Low-Income Population: Randomized Controlled Trial Protocol  

PubMed Central

Background Patients on insulin glargine typically visit a clinician to obtain advice on how to adjust their insulin dose. These multiple clinic visits can be costly and time-consuming, particularly for low-income patients. It may be feasible to achieve insulin titration through text messages and phone calls with patients instead of face-to-face clinic visits. Objective The objectives of this study are to (1) evaluate if the Mobile Insulin Titration Intervention (MITI) is clinically effective by helping patients reach their optimal dose of insulin glargine, (2) determine if the intervention is feasible within the setting and population, (3) assess patient satisfaction with the intervention, and (4) measure the costs associated with this intervention. Methods This is a pilot study evaluating an approach to insulin titration using text messages and phone calls among patients with insulin-dependent type 2 diabetes in the outpatient medical clinic of Bellevue Hospital Center, a safety-net hospital in New York City. Patients will be randomized in a 1:1 ratio to either the MITI arm (texting/phone call intervention) or the usual-care arm (in-person clinic visits). Using a Web-based platform, weekday text messages will be sent to patients in the MITI arm, asking them to text back their fasting blood glucose values. In addition to daily reviews for alarm values, a clinician will rereview the texted values weekly, consult our physician-approved titration algorithm, and call the patients with advice on how to adjust their insulin dose. The primary outcome will be whether or not a patient reaches his/her optimal dose of insulin glargine within 12 weeks. Results Recruitment for this study occurred between June 2013 and December 2014. We are continuing to collect intervention and follow-up data from our patients who are currently enrolled. The results of our data analysis are expected to be available in 2015. Conclusions This study explores the use of widely-available text messaging and voice technologies for insulin titration. We aim to show that remote insulin titration is clinically effective, feasible, satisfactory, and cost saving for low-income patients in a busy, urban clinic. Trial Registration Trial Registration: Clinicaltrials.gov NCT01879579; http://clinicaltrials.gov/ct2/show/NCT01879579 (Archived by WebCite at http://www.webcitation.org/6WUEgjZUO). PMID:25794243

Levy, Natalie; Nilo, Annielyn; Singer, Karyn; Bernik, Lidia S; Etiebet, Mary-Ann; Fang, Yixin; Cho, James; Natarajan, Sundar

2015-01-01

341

Standard test method for total base number of petroleum products by potentiometric perchloric acid titration  

SciTech Connect

This method covers the determination of basic constituents in petroleum products by titration with perchloric acid. For many materials the results obtained by this method will be similar to those obtained by Method D 664-IP 177. With certain compounds such as strongly overbased oil additives and nitrogenous polymeric compounds, higher results may be obtained. Summary of method: the sample is dissolved in an essentially anhydrous mixture of chlorobenzene and glacial acetic acid and titrated with a solution of perchloric acid in glacial acetic acid with a potentiometric titrimeter. A glass indicating electrode and a calomel reference electrode are used, the latter being connected with the sample solution by means of a salt bridge. The meter readings are plotted against the respective volumes of titrating solution, and the end point is taken at the inflection in the resulting curve. Occasionally certain used oils give no inflection in the standard titration, in which case a back titration modification with sodium acetate titrant is employed. Total base number is the quantity of perchloric acid expressed in terms of the equivalent number of milligrams of potassium hydroxide that is required to neutralize all basic constituents present in 1 g of sample.

Not Available

1980-01-01

342

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.

1999-10-01

343

Studies on fluorescein-III The acid strengths of fluorescein as shown by potentiometric titration.  

PubMed

Potentiometric back-titration of yellow solid fluorescein (H(2)Fl) and of red solid fluorescein in alkali with acid yielded titration curves that were practically identical in shape and position. The end-points at pH 8.5, 5.40 and 3.3 corresponded, respectively, to titration of the excess of standard alkali, and the successive protonations Fl(2-) + H(+) = HFl(-) and HFl(-) + H(+) = H(2)Fl. The pH at the mid-point of the first protonation yielded a value of 6.36 for pK(HFl) (ionic strength 0.10). Because of precipitation of yellow fluorescein during the second protonation step, a value for pK(H(2)Fl) could not be obtained. The total concentration of fluorescein at the first appearance of the precipitate fell on the curve for the solubility of yellow fluorescein as a function of pH. The titrations and the pK values found for the three acid groups of protonated fluorescein (H(3)Fl(+)) have been interpreted on the basis that in water fluorescein exists in only one structural form the yellow zwitterion. Similar back-titrations of alkalinized solutions of yellow or red fluorescein in 50% aqueous ethanol showed that in this medium fluorescein is present in only one form, presumably the quinonoid structure, with much weaker apparent acid functions, pK'(1) = 6.38 and PK'(2) = 7.16 (ionic strength 0.10). PMID:18964223

Diehl, H; Horchak-Morris, N; Hefley, A J; Munson, L F; Markuszewski, R

1986-11-01

344

Using spectrophotometric titrations to characterize humic acid reactivity at environmental concentrations.  

PubMed

Potentiometric titration is a common method to characterize dissolved organic matter (DOM) reactivity. Because of the sensitivity of pH electrodes, it is necessary to work with very high DOM (>1 g/L) concentrations that are unrealistic compared to those found in natural waters (0.1 to 100 mg/L). To obtain proton binding data for concentrations closer to environmental values, spectroscopic titration methodology is a viable alternative to traditional potentiometric titrations. Spectrophotometric titrations and UV-visible spectra of a diluted solution of purified Aldrich humic acid (5 mgDOC/L) are used to estimate changes in proton binding moieties as function of pH and ionic strength after calculation of differential absorbance spectra variations. After electrostatic correction of spectrophotometric data, there is a linear operational correlation between spectrophotometric and potentiometric data which can be used as a transfer function between the two properties. Spectrophotometric titrations are then used to determine the changes of humic acid protonation after adsorption onto alpha-alumina. PMID:20698549

Janot, Noémie; Reiller, Pascal E; Korshin, Gregory V; Benedetti, Marc F

2010-09-01

345

Potentiometric titrations of Bacillus subtilis cells to low pH and a comparison of modeling approaches  

Microsoft Academic Search

To provide constraints on the speciation of bacterial surface functional groups, we have conducted potentiometric titrations using the gram-positive aerobic species Bacillus subtilis, covering the pH range 2.1 to 9.8. Titration experiments were conducted using an auto-titrator assembly, with the bacteria suspended in fixed ionic strength (0.01 to 0.3 M) NaClO4 solutions. We observed significant adsorption of protons over the

Jeremy B. Fein; Jean-François Boily; Nathan Yee; Drew Gorman-Lewis; Benjamin F. Turner

2005-01-01

346

Physicochemical studies on BELGARD EV and BELGARD EV 2000 solutions. Part II. Potentiometric and conductometric acid-base titrations  

Microsoft Academic Search

The two anti-scale agents BELGARD EV (BELEV) and BELGARD EV 2000 (BELEV 2) are titrated against standard NaOH solution. Both the potentiometric (pH metric) and the conductometric titration techniques are used. For the sake of comparison the reaction of the monomer (maleic acid, H2M) is also investigated. The two titration techniques reveal that H2M neutralizes along two equal steps. The

A. M. Shams El Din; R. A. Mohammed

1996-01-01

347

Influence of kinetics on the determination of the surface reactivity of oxide suspensions by acid–base titration  

Microsoft Academic Search

The effect of acid–base titration protocol and speed on pH measurement and surface charge calculation was studied on suspensions of ?-alumina, hematite, goethite, and silica, whose size and porosity have been well characterized. The titration protocol has an important effect on surface charge calculation as well as on acid–base constants obtained by fitting of the titration curves. Variations of pH

M. Duc; F. Adekola; G. Lefèvre; M. Fédoroff

2006-01-01

348

Methods for the determination of cyclopropenoid fatty acids. II. A stepwise hydrogen bromide titration method for cyclopropenid and epoxy derivatives  

Microsoft Academic Search

A rapid titration method is described for the quantitative determination of both cyclopropenoid and epoxy fatty acid derivatives\\u000a in mixtures. It was found that epoxy compounds can be titrated selectively with Durbetaki reagent at 3C without interference\\u000a from cyclopropenoid derivatives. Cyclopropenoid derivatives can be titrated much more rapidly to a much sharper end point\\u000a a 55C that at room temperature.

J. A. Harris; F. C. Magne; E. L. Skau

1963-01-01

349

FIA acid-base titrations with a new flow-through pH detector.  

PubMed

A pH-sensitive detector for flow-through potentiometry based on a graphite/quinhydrone composite electrode was applied for flow-injection analysis (FIA) titrations. Hydrochloric acid and acetic acid were titrated by injection of samples into a sodium hydroxide carrier solution. System conditions were optimised by variation of flow rate, injection volume and titrant concentration. The parameters sampling frequency, residence time and dispersion coefficient were determined. The evaluation of peak width (time between the two inflection points on each side of the peak), peak area and slope of the raising edge of the peak lead were studied with respect to their use for calibration. Hydrochloric acid and acetic acid could be titrated down to a concentration of 2 x 10(-4) mol L(-1) using 150-microL injection volumes, which is almost ten times lower than can be achieved using colour indicators and a spectrophotometric detection. PMID:16034616

Kahlert, H; Pörksen, J R; Behnert, J; Scholz, F

2005-08-01

350

Ion-selective optode nanospheres as heterogeneous indicator reagents in complexometric titrations.  

PubMed

Traditionally, optical titrations of inorganic ions are based on a rapid and visible color change at the end point with water-soluble organic dyes as indicators. Adequate selectivity is required for both the indicator and the complexing agent, which is often limited. We present here alternative, heterogeneous ionophore-based ion-selective nanospheres as indicators and chelators for optical titrations. The indicating nanospheres rely on a weaker extraction of the analyte of interest by ion-exchange, owing to the additional incorporation of a lipophilic pH indicator in the nanosphere core. Ca(2+) titration was demonstrated as a proof-of-concept. Both the chelating and the indicating nanospheres showed good selectivity and a wide working pH range. PMID:25622089

Zhai, Jingying; Xie, Xiaojiang; Bakker, Eric

2015-03-01

351

Linear titration plots for the analysis of mixtures of three weak acids or bases.  

PubMed

Linearly related functions have been derived which enable mixtures of three weak acids or bases in solution to be analysed by means of pH-titration data. This theory has been tested with data from the titration of a variety of mixtures of acids. The data required for the functions are pH, volume of titrant, the equilibrium constants relevant to the mixture, and an independently determined equivalence volume. This may be the equivalence volume for one of the components of the mixture or the sum of the equivalence volumes for any two or all three of the components. It is immaterial how this equivalence volume is obtained, but it is usually possible to obtain the total equivalence volume from data in another part of the same titration curve (when a large excess of titrant has been added). PMID:18963621

Midgley, D; McCallum, C

1984-06-01

352

Potentiometric Measurement of Transition Ranges and Titration Errors for Acid/Base Indicators  

NASA Astrophysics Data System (ADS)

Sophomore analytical chemistry courses typically devote a substantial amount of lecture time to acid/base equilibrium theory, and usually include at least one laboratory project employing potentiometric titrations. In an effort to provide students a laboratory experience that more directly supports their classroom discussions on this important topic, an experiment involving potentiometric measurement of transition ranges and titration errors for common acid/base indicators has been developed. The pH and visually-assessed color of a millimolar strong acid/base system are monitored as a function of added titrant volume, and the resultant data plotted to permit determination of the indicator's transition range and associated titration error. Student response is typically quite positive, and the measured quantities correlate reasonably well to literature values.

Flowers, Paul A.

1997-07-01

353

Acid-Base Titration of (S)-Aspartic Acid: A Circular Dichroism Spectrophotometry Experiment  

NASA Astrophysics Data System (ADS)

The magnitude of the circular dichroism of (S)-aspartic acid in aqueous solutions at a fixed wavelength varies with the addition of strong base. This laboratory experiment consists of the circular dichroism spectrophotometric acid-base titration of (S)-aspartic acid in dilute aqueous solutions, and the use of the resulting data to determine the ionization constant of the protonated amino group. The work familiarizes students with circular dichroism and illustrates the possibility of performing titrations using a less usual instrumental method of following the course of a reaction. It shows the use of a chiroptical property in the determination of the concentration in solution of an optically active molecule, and exemplifies the use of a spectrophotometric titration in the determination of an ionization constant.

Cavaleiro, Ana M. V.; Pedrosa de Jesus, Júlio D.

2000-09-01

354

Ion-ion correlation and charge reversal at titrating solid interfaces  

E-print Network

Confronting grand canonical titration Monte Carlo simulations (MC) with recently published titration and charge reversal (CR) experiments on silica surfaces by Dove et al. and van der Heyden it et al, we show that ion-ion correlations quantitatively explain why divalent counterions strongly promote surface charge which, in turn, eventually causes a charge reversal (CR). Titration and CR results from simulations and experiments are in excellent agreement without any fitting parameters. This is the first unambiguous evidence that ion-ion correlations are instrumental in the creation of highly charged surfaces and responsible for their CR. Finally, we show that charge correlations result in "anomalous" charge regulation in strongly coupled conditions in qualitative desagreement with its classical treatment.

Christophe Labbez; Bo Jonsson; Michal Skarba; Michal Borkovec

2008-12-01

355

Optical Photometric Observations of GEO Debris  

NASA Astrophysics Data System (ADS)

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

2010-09-01

356

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

2009-01-01

357

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

2009-01-01

358

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

2009-02-01

359

Optical Photometric Observations of GEO Debris  

NASA Technical Reports Server (NTRS)

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

2010-01-01

360

A photometric model for asteroid (21) Lutetia  

NASA Astrophysics Data System (ADS)

(21) Lutetia has been successfully observed (July 10, 2010) by the ESA Rosetta spacecraft during its journey toward the comet 67P/Churyumov-Gerasimenko (Sierks et al. 2011, Coradini et al. 2011). All the available data show intriguing characteristics with a complex surface composition interpretation (Barucci et al. 2012). The quite high mean density estimation (3.4±0.3, Pätzold et al. 2011) together with the unmatching density derived from the most probable surface compositions raise a hypothesis of (21) Lutetia having a metal core (Weiss et al 2012). The surface geology of (21) Lutetia is also highly complex with significant interactions between ancient and more recent structures (Thomas et al; 2012). The large craters and lineaments show that the object was heavily battered in the past, probably losing almost all of its crust in the process (Massironi et al 2012). If (21) Lutetia is a partially differentiated asteroid with an impact-stripped crust, a complete study of variegations might help in elucidating this event. Regions or strips of different albedo might indicate heavier- or lighter-battered surface histories. Albedo variations have been detected by Leyrat et al. (2012) in the visible wavelengths. In this work, we present a deeper analysis of the Lutetia photometric properties. For such analysis, a full set of pipelines was developed in the Python 2.7.6 language. Images obtained by the OSIRIS cameras, NAC and WAC, were used alongside the shape model provided by L. Jorda to derive for each facet the luminance angles and the correct I/F. The pipeline takes image pixels and matches with facets on different observational conditions. Facets are iteratively fitted by a phase function and a disk function. Several phase functions were tested as Akimov (1976), Kaasalainen (Kaasalainen et al. 2003), Schroder (Schroder et al; 2013) and polynomial and were implemented; for disk function, McEwen (1991), Akimov and Minnaert (1941) were used. The method can be also applicable for any body with resolved images and precise shape model. As a result, all phase and topological effects are removed and equigonal albedo maps (Shkuratov et al. 2011) were retrieved showing (21) Lutetia real variegations. Images close to the opposition surge, off linear regime, were handled with the Akimov or Kaasalainen functions. The obtained results will be presented and discussed, in particular maps with a distribution of opposition surge properties, such as angular width and amplitude of the surge. The opposition parameters give additional information about the grain-size distribution and grain transparency, and were only retrieved for facets with I/F of phase angles lower than 3 degrees.

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

2014-07-01

361

COMPLEXOMETRIC AND PHOTOMETRIC DETERMINATION OF THORIUM IN MINERALS AND ORES  

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

Zaikovskii

1959-01-01

362

A PHOTOMETRIC AND SPECTROSCOPIC STUDY OF DWARF AND GIANT GALAXIES IN THE COMA CLUSTER. I. WIDE-AREA PHOTOMETRIC SURVEY: OBSERVATION AND DATA ANALYSIS1  

E-print Network

A PHOTOMETRIC AND SPECTROSCOPIC STUDY OF DWARF AND GIANT GALAXIES IN THE COMA CLUSTER. I. WIDE 1982), photometric studies (e.g., Strom & Strom 1978; God- win & Peach 1977; Visvanathan & Sandage 1977-AREA PHOTOMETRIC SURVEY: OBSERVATION AND DATA ANALYSIS1 Y. Komiyama,2 M. Sekiguchi,3 N. Kashikawa,4 M. Yagi,4 M

Iye, Masanori

363

Determination of sulfur compounds in hydrotreated transformer base oil by potentiometric titration.  

PubMed

A method was developed to analyze the distribution of sulfur compounds in model sulfur compounds by potentiometric titration, and applied to analyze hydrotreated transformer base oil. Model thioethers were oxidized to corresponding sulfoxides by tetrabutylammonium periodate and sodium metaperiodate, respectively, and the sulfoxides were titrated by perchloric acid titrant in acetic anhydride. The contents of aliphatic thioethers and total thioethers were then determined from that of sulfoxides in solution. The method was applied to determine the organic sulfur compounds in hydrotreated transformer base oil. PMID:15984215

Chao, Qiu; Sheng, Han; Cheng, Xingguo; Ren, Tianhui

2005-06-01

364

Selective two-step titration of thorium by sulfate displacement of the diethylenetriaminepentaacetic acid complex  

SciTech Connect

Thorium and other metals are complexed with excess diethylenetriaminepentaacetic acid (DTPA) at pH 1.4, the excess DTPA is titrated with Bi(III) to a xylenol orange end point, sulfate is added to complex Th(IV), and the displaced DTPA again is titrated with Bi(III). Of 61 metal ions and nonmetal anions tested, only Ga(III), Sc(III), tungstate, citrate, oxalate, and thiosulfate interfere seriously. Lesser interferences are In(III), Zr(IV), V(IV), and permanganate. The standard deviation is 2 ..mu..g for 56 to 840 ..mu..g Th.

Kiefer, P.

1980-07-01

365

Determination of sulphated glycosaminoglycans by automated potentiometric titration with simple coated-wire electrodes.  

PubMed

A method for the determination of sulphated glycosaminoglycans is based on their precipitation with (1-ethoxycarbonyl)pentadecyltrimethylammonium bromide (Septonex), the excess of which is back-titrated with sodium tetraphenylborate. The titration is monitored by a simple coated-wire ion-selective electrode with a plasticized poly(vinyl chloride) membrane on aluminium wire. Under certain conditions the results are almost independent of the relative molecular mass of glycosaminoglycans. The method has been applied to the determination of the active ingredient in the pharmaceutical preparation, heparon injection. PMID:2490091

Dohnal, J; Vytras, K; Roubal, Z; Zemanová, I

1989-01-01

366

The influence of hydrogen peroxide and pH on the Mohr titration.  

PubMed

The official Japanese method for determination of chloride in hot-spring waters requires any H(2)S present to be oxidized with hydrogen peroxide in ammoniacal medium. When this was done, and the solution was titrated with silver nitrate at pH 9.7, the indicator colour changed from yellow to brownish grey, owing to reduction of silver ions to the metal by hydrogen peroxide. The effect can be eliminated by adjusting the pH to 7.0-7.5 before the titration. PMID:18965181

Fujita, R

1991-05-01

367

Acid-base titration curves for acids with very small ratios of successive dissociation constants.  

PubMed

The shapes of the potentiometric acid-base titration curves obtained in the neutralizations of polyfunctional acids or bases for which each successive dissociation constant is smaller than the following one are examined. In the region 0 < < 1 (where is the fraction of the equivalent volume of reagent that has been added) the slope of the titration curve decreases as the number j of acidic or basic sites increases. The difference between the pH-values at = 0.75 and = 0.25 has (1 j)log 9 as the lower limit of its maximum value. PMID:18961431

Campbell, B H; Meites, L

1974-02-01

368

Survey of the year 2004: literature on applications of isothermal titration calorimetry.  

PubMed

The market for commercially available isothermal titration calorimeters continues to grow as new applications and methodologies are developed. Concomitantly the number of users (and abusers) increases dramatically, resulting in a steady increase in the number of publications in which isothermal titration calorimetry (ITC) plays a role. In the present review, we will focus on areas where ITC is making a significant contribution and will highlight some interesting applications of the technique. This overview of papers published in 2004 also discusses current issues of interest in the development of ITC as a tool of choice in the determination of the thermodynamics of molecular recognition and interaction. PMID:16220545

Ababou, Abdessamad; Ladbury, John E

2006-01-01

369

DCTA Titration of iron(III) with p-aminosalicylic acid and sodium azide as indicators.  

PubMed

Iron(III) has been determined by DCTA titration with p-aminosalicylic acid and sodium azide as indicator at pH 1.4-3.5. The titrations are rapid, simple, accurate and reversible and as little as 0.15 mg of iron(III) can be determined in the presence of up to 100 times as much of certain ions. Cadmium, zinc, lead, copper(II), aluminium, thorium, oxalate, phosphate, fluoride and sulphide interfere. The method is utilized for determination of iron(III) in presence of copper(II) or lead and in limestone, cement and haemetite. PMID:18962489

Parkash, R; Bala, R; Lal Singhal, R

1979-07-01

370

Photometric relief of the previously uninvestigated surface of mercury  

NASA Astrophysics Data System (ADS)

The results of investigations of the surface relief of Mercury with a classical photometric method are reported. A subject of the photometric method is the intensity of light reflected by the surface of the planet. The main data for the photometric study are the high-resolution images of Mercury received from the MESSENGER space station during its first flyby over Mercury. The images of the surface of Mercury were downloaded from the NASA web-site (http://messenger.jhuapl.edu) and converted to a digital form for photometric measurements. The reflectance characteristics of the surface were calculated according to the model of a three-dimensional scattering phase function (Shevchenko, 1979; 2004a; 2006). From the photometric processing of the space-borne images, the reflectance of four morphologic types of the surface structure of Mercury was determined. With the Hapke model of the bidirectional reflectance (Hapke, 2001), the structural inhomogeneity of the regions of the morphologic forms with centimeter-sized rough-ness was estimated.

Pugacheva, S. G.; Shevchenko, V. V.

2014-01-01

371

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.

2007-01-01

372

Values of the photometric parameters of Mars and their interpretation  

NASA Technical Reports Server (NTRS)

Photometric data for the Martian disk obtained by Thorpe from television-camera pictures taken by Mariner 9 were used to derive values for the parameters in the photometric function. The photometric function can be applied to Mars and to the design of cameras for photography of Mars. Values of the parameters are for one wavelength only, 0.56 micros and are average or effective values for the Martian disk. The values derived were interpreted to provide semi-quantitative information on the soil. The results do not disagree with other indications that the effective mean diameter of the surface particles is about 400 micros. Another result is that the mean intercenter spacing of adjacent particles may be about 4/3 of the mean diameter.

Weaver, W. R.; Meador, W. E.; Wood, G. P.

1974-01-01

373

Effects of photometric geometry on spectral reflectance measurements. [celestial bodies  

NASA Technical Reports Server (NTRS)

Progress is reported in obtaining valuable results needed for the full interpretation of the spectral reflectance curves of solar system objects. The degree to which photometric geometry affects spectral reflectance curves was demonstrated. Various forms of photometric functions were compared and a function adequate for describing the scattering properties of low and moderately reflecting materials was developed and applied in a study of the phase coefficients of various materials, as well as in a study of how the shape of a body affects the spectral reflectance properties. The adequacy of the photometric function for Mars-like analogs was studied. The goniometer system is being converted to a computer driven mode. As soon as computer controls are integrated in the goniometer, the phase dependence 0.95 micron feature in meteorite spectra is scheduled to begin.

Veverka, J.; Gradie, J. C.

1981-01-01

374

Photometric Calibration of the Swift Ultraviolet/Optical Telescope  

E-print Network

We present the photometric calibration of the Swift UltraViolet/Optical Telescope (UVOT) which includes: optimum photometric and background apertures, effective area curves, colour transformations, conversion factors for count rates to flux, and the photometric zero points (which are accurate to better than 4 per cent) for each of the seven UVOT broadband filters. The calibration was performed with observations of standard stars and standard star fields that represent a wide range of spectral star types. The calibration results include the position dependent uniformity, and instrument response over the 1600-8000A operational range. Because the UVOT is a photon counting instrument, we also discuss the effect of coincidence loss on the calibration results. We provide practical guidelines for using the calibration in UVOT data analysis. The results presented here supersede previous calibration results.

T. S. Poole; A. A. Breeveld; M. J. Page; W. Landsman; S. T. Holland; P. Roming; N. P. M. Kuin; P. J. Brown; C. Gronwall; S. Hunsberger; S. Koch; K. O. Mason; P. Schady; D. Vanden Berk; A. J. Blustin; P. Boyd; P. Broos; M. Carter; M. M. Chester; A. Cucchiara; B. Hancock; H. Huckle; S. Immler; M. Ivanushkina; T. Kennedy; F. Marshall; A. Morgan; S. Pandey; M. de Pasquale; P. J. Smith; M. Still

2007-11-09

375

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.

2010-01-01

376

CALIBRATING PHOTOMETRIC REDSHIFT DISTRIBUTIONS WITH CROSS-CORRELATIONS  

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)

2010-12-01

377

Charge Density Quantification of Polyelectrolyte Polysaccharides by Conductometric Titration: An Analytical Chemistry Experiment  

ERIC Educational Resources Information Center

An easy analytical method for determination of the charge density of polyelectrolytes, including polysaccharides and other biopolymers, is presented. The basic principles of conductometric titration, which is used in the pulp and paper industry as well as in colloid and interface science, were adapted to quantify the charge densities of a…

Farris, Stefano; Mora, Luigi; Capretti, Giorgio; Piergiovanni, Luciano

2012-01-01

378

Analysis of polymeric quaternary ammonium salts as found in cosmetics by metachromatic polyelectrolyte titration  

Microsoft Academic Search

Metachromatic polyelectrolyte titration was investigated as a means of analyzing polymeric quaternary ammonium salts (polyquaterniums) of relatively low charge density used as ingredients in cosmetics. They are of possible toxicological concern, but little is known of their environmental fate and behavior. With o-toluidine blue as the indicator, determination of the concentration of a range of polyquaterniums of commercial importance and

J. L. Cumming; D. W. Hawker; C. Matthews; H. F. Chapman; K. Nugent

2010-01-01

379

Titration of Monoprotic Acids with Sodium Hydroxide Contaminated by Sodium Carbonate.  

ERIC Educational Resources Information Center

Discusses the effects of using carbon dioxide contaminated sodium hydroxide solution as a titrant for a solution of a weak monoprotic acid and the resulting distortion of the titration curve in comparison to one obtained when an uncontaminated titrant is used. (CW)

Michalowski, Tadeusz

1988-01-01

380

An automated differential thermal and potentiometric titration apparatus for binding studies.  

PubMed

A differential pH-thermal titration apparatus is described which can detect pH differences with a sensitivity of +/- 0.0001 pH units and a thermal sensitivity of +/- 0.00002 degree C at a time constant of 0.1 s. With a reaction which yields 1 kcal mol-1, the current system can detect concentrations as low as 4 X 10(-6) M or, in a 2 ml volume, a total amount of 40 nmol. With a time constant of 0.1 s, the sensitivity is 20 +/- 4 micro degrees C. The experimental protocol is specified by a microprocessor and three modes of operation are possible: titration at constant rate of reagent addition, titration at variable rates of addition so that the contents of both cells are at either constant pH or at a constant temperature and variable rate when a rate of change is specified. Experimental data are collected in files, corrected for heat loss, initial baseline drift, and changes in volume. The final corrected data from the standardized run of 0.01338 M HCl in 0.2 M KCl at 25 degrees C calibrate the pH scale and yield the calorimetric conversion constants and pKw which are calculated and stored for subsequent corrections for the titration of an unknown acid or the measurement of binding constants and heats. PMID:3998380

Berger, R L; Cascio, H E; Davids, N; Gibson, C G; Marini, M; Thiebault, L

1985-03-01

381

Impairment and Deportment Responses to Different Methylphenidate Doses in Children With ADHD: The MTA Titration Trial  

Microsoft Academic Search

ObjectiveResults of the NIMH Collaborative Multisite Multimodal Treatment Study of Children With Attention-Deficit\\/Hyperactivity Disorder (MTA) were analyzed to determine whether a double-blind, placebo-controlled methylphenidate (MPH) titration trial identified the best MPH dose for each child with attention-deficit\\/hyperactivity disorder (ADHD).

LAURENCE L. GREENHILL; JAMES M. SWANSON; BENEDETTO VITIELLO; MARK DAVIES; WALTER CLEVENGER; MIN WU; L. EUGENE ARNOLD; HOWARD B. ABIKOFF; OSCAR G. BUKSTEIN; C. KEITH CONNERS; GLEN R. ELLIOTT; LILY HECHTMAN; STEPHEN P. HINSHAW; BETSY HOZA; PETER S. JENSEN; HELENA C. KRAEMER; JOHN S. MARCH; JEFFREY H. NEWCORN; JOANNE B. SEVERE; KAREN WELLS; TIMOTHY WIGAL

2001-01-01

382

Potentiometric titration of bisarenechromium compounds with an ion-selective electrode  

SciTech Connect

A liquid-membrane ion-selective electrode was developed for determining bisbenzene-chromium and its electrochemical and analytical characteristics studied. Methods have also been developed for determining bisarenechromium compounds in the industrial product and its waste waters by potentiometric titration with sodium tetraphenylborate solution.

Gur'ev, I.A.; Gur'eva, Z.M.; Sankova, E.V.; Sirotkin, N.I.

1986-06-10

383

A new linear potentiometric titration method for the determination of deacetylation degree of chitosan  

Microsoft Academic Search

The degree of deacetylation (DD) is one of the most important properties of chitosan. Therefore, a simple, rapid and reliable method for the determination of DD of chitosan is essential. In this report, two new potentiometric titration functions are derived for the determination of DD of chitosan. The effects of the precipitation and the errors induced in pH measurement are

Xuan Jiang; Lirong Chen; Wei Zhong

2003-01-01

384

Lead biosorption study with Rhizopus arrhizus using a metal-based titration technique  

Microsoft Academic Search

Acid–base and metal-based potentiometric titration methods were used to analyze sorption mechanisms of lead by Rhizopus arrhizus fungal biomass. Biosorption was not considered globally but as the result of successive sorption reactions on various binding sites with different selectivities. Precipitation occurred rapidly when lead concentration increased. Lead was sorbed essentially by carboxylic groups and by phosphates and sulfonates (less abundant)

Ghinwa Naja; Christian Mustin; Jacques Berthelin; Bohumil Volesky

2005-01-01

385

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

2013-05-01

386

Application of a focus formation assay for detection and titration of porcine epidemic diarrhea virus  

Microsoft Academic Search

A focus formation assay (FFA) for detection and titration of porcine epidemic diarrhea virus (PEDV) in a micro-culture system using Vero cells and PAP staining technique was evaluated. A linear correlation between the virus dilution and virus titer determined by FFA was observed between the range of 10 and 30 foci per well. Comparative analysis between FFA and plaque assay

Deu John M. Cruz; Hyun-Jin Shin

2007-01-01

387

Single-experiment displacement assay for quantifying high-affinity binding by isothermal titration calorimetry.  

PubMed

Isothermal titration calorimetry (ITC) is the gold standard for dissecting the thermodynamics of a biomolecular binding process within a single experiment. However, reliable determination of the dissociation constant (KD) from a single titration is typically limited to the range 100?M>KD>1nM. Interactions characterized by a lower KD can be assessed indirectly by so-called competition or displacement assays, provided that a suitable competitive ligand is available whose KD falls within the directly accessible window. However, this protocol is limited by the fact that it necessitates at least two titrations to characterize one high-affinity inhibitor, resulting in considerable consumption of both sample material and time. Here, we introduce a fast and efficient ITC displacement assay that allows for the simultaneous characterization of both a high-affinity ligand and a moderate-affinity ligand competing for the same binding site on a receptor within a single experiment. The protocol is based on a titration of the high-affinity ligand into a solution containing the moderate-affinity ligand bound to the receptor present in excess. The resulting biphasic binding isotherm enables accurate and precise determination of KD values and binding enthalpies (?H) of both ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation, explore its potential and limitations with the aid of simulations and statistical analyses, and elaborate on potential applications to protein-inhibitor interactions. PMID:25461813

Krainer, Georg; Keller, Sandro

2015-04-01

388

Use of tetrabutylammonium tribromide for voltametric titration of unsaturation in vegetable oils and fatty acids  

Microsoft Academic Search

The use of tetrabutylammonium tribromide as reagent for bromination of carbon-carbon double bonds of fatty acids and vegetable\\u000a oils, followed by a voltametric titration of tribromide and bromide ions, has been studied. This method is easy and fast,\\u000a and results show good accuracy and high sensitivity.

J. Berthelota; P. L. Desbène; A. Desbène-Monvernay

1993-01-01

389

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.

390

Selective coulometric release of ions from ion selective polymeric membranes for calibration-free titrations.  

PubMed

Coulometry belongs to one of the few known calibration-free techniques and is therefore highly attractive for chemical analysis. Titrations performed by the coulometric generation of reactants is a well-known approach in electrochemistry, but suffers from limited selectivity and is therefore not generally suited for samples of varying or unknown composition. Here, the selective coulometric release of ionic reagents from ion-selective polymeric membrane materials ordinarily used for the fabrication of ion-selective electrodes is described. The selectivity of such membranes can be tuned to a significant extent by the type and concentration of ionophore and lipophilic ion-exchanger and is today well understood. An anodic current of fixed magnitude and duration may be imposed across such a membrane to release a defined quantity of ions with high selectivity and precision. Since the applied current relates to a defined ion flux, a variety of non-redox active ions may be accurately released with this technique. In this work, the released titrant's activity was measured with a second ionophore-based ion-selective electrode and corresponded well with expected dosage levels on the basis of Faraday's law of electrolysis. Initial examples of coulometric titrations explored here include the release of calcium ions for complexometric titrations, including back titrations, and the release of barium ions to determine sulfate. PMID:17028722

Bhakthavatsalam, Vishnupriya; Shvarev, Alexey; Bakker, Eric

2006-08-01

391

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

Paris-Sud XI, Université de

392

Avian influenza virus isolation, propagation and titration in embryonated chicken eggs  

Technology Transfer Automated Retrieval System (TEKTRAN)

Avian influenza (AI) virus is usually isolated, propagated, and titrated in embryonated chickens eggs (ECE). Most any sample type can be accommodated for culture with appropriate processing. Isolation may also be accomplished in cell culture particularly if mammalian lineage isolates are suspected, ...

393

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

2007-01-01

394

Subsite binding energies of an exo-polygalacturonase using isothermal titration calorimetry  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thermodynamic parameters for binding of a series of galacturonic acid oligomers to an exo-polygalacturonase, RPG16 from Rhizopus oryzae, were determined by isothermal titration calorimetry. Binding of oligomers varying in chain length from two to five galacturonic acid residues is an exothermic proc...

395

Remote titration of carvedilol for heart failure patients by advanced practice nurses  

Microsoft Academic Search

Background?-blockers (BB) in the treatment of heart failure (HF) are frequently underprescribed and underdosed, perhaps because of recommendations for office visits at each dose change. In previous work, we demonstrated the feasibility of remote telephonically assisted BB titration and found favorable effects on morbidity, time to target dose, and low withdrawal rates. In the current expanded evaluation, we reasoned that

Deborah Moyer-Knox; Teresa M. Mueller; Karen Vuckovic; Lisa Mischke; Randall E. Williams

2004-01-01

396

TITRATION OF A BRUCELLA PROTEIN ALLERGEN IN SHEEP SENSITIZED WITH BRUCELLA MELITENSIS  

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

397

Sequential injection redox or acid–base titration for determination of ascorbic acid or acetic acid  

Microsoft Academic Search

Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to

Narong Lenghor; Jaroon Jakmunee; Michael Vilen; Rolf Sara; Gary D Christian; Kate Grudpan

2002-01-01

398

Trace analysis of acids and bases by conductometric titration with multiparametric non-linear regression.  

PubMed

A chemometric method for analysis of conductometric titration data was introduced to extend its applicability to lower concentrations and more complex acid-base systems. Auxiliary pH measurements were made during the titration to assist the calculation of the distribution of protonable species on base of known or guessed equilibrium constants. Conductivity values of each ionized or ionizable species possibly present in the sample were introduced in a general equation where the only unknown parameters were the total concentrations of (conjugated) bases and of strong electrolytes not involved in acid-base equilibria. All these concentrations were adjusted by a multiparametric nonlinear regression (NLR) method, based on the Levenberg-Marquardt algorithm. This first conductometric titration method with NLR analysis (CT-NLR) was successfully applied to simulated conductometric titration data and to synthetic samples with multiple components at concentrations as low as those found in rainwater (approximately 10 micromol L(-1)). It was possible to resolve and quantify mixtures containing a strong acid, formic acid, acetic acid, ammonium ion, bicarbonate and inert electrolyte with accuracy of 5% or better. PMID:18970555

Coelho, Lúcia H G; Gutz, Ivano G R

2006-03-15

399

Evaluation of the number of ionogenic groups of inulinase by acid-base titration  

Microsoft Academic Search

Acid base titration showed that Aspergillus awamori inulinase includes 178 asparaginic and glutamic acid residues, 20 histidine, 10 serine, and 34 lysine and tyrosine residues.\\u000a Denaturation temperature for this enzyme was calculated using analysis of the proportion of stabilizing and destabilizing\\u000a amino acids in the molecule.

T. A. Kovaleva; M. G. Holyavka; S. G. Rezvan; S. V. Kozhedub

2008-01-01

400

Titrating Rituximab to Circulating B Cells to Optimize Lymphocytolytic Therapy in Idiopathic Membranous Nephropathy  

Microsoft Academic Search

Background and Objectives: Rituximab, given in four weekly doses, is a promising treatment for idiopathic membranous nephropathy and other immune-mediated diseases and lymphoproliferative disorders. This multidose regimen, however, may cause hypersensitivity reactions and is extremely expensive. This study was aimed at evaluating whether titrating rituximab to circulating CD20 B cells may improve safety and limit costs of treatment. Design, Setting,

Paolo Cravedi; Piero Ruggenenti; Maria Chiara Sghirlanzoni; Giuseppe Remuzzi; Mario Negri; Villa Camozzi

401

Non-euclidean simplex optimization. [Application to potentiometric titration of Pu  

Microsoft Academic Search

Geometric optimization techniques useful for studying chemical equilibrium traditionally rely upon principles of euclidean geometry, but such algorithms may also be based upon principles of a non-euclidean geometry. The sequential simplex method is adapted to the hyperbolic plane, and application of optimization to problems such as the potentiometric titration of plutonium is suggested.

1977-01-01

402

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,

M. W. H. Pijnenburg; W. C. J. Hop; Jongste de J. C; E. M. Bakker

2005-01-01

403

Exact Analysis of Competition Ligand Binding by Displacement Isothermal Titration Calorimetry  

Microsoft Academic Search

A rigorous method for the least-squares nonlinear regression analysis of displacement isothermal titration calorimetric data is presented. The method can fit the binding isotherm of a ligand which is competitively inhibited in its binding by another bound ligand to a molecule with n identical and independent binding sites. There are no other assumptions for the method and no approximations. Analysis

Bent W. Sigurskjold

2000-01-01

404

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

1975-01-01

405

Tested Demonstrations: Comparison of Strong Acid and Weak Acid Titration Curves.  

ERIC Educational Resources Information Center

A lecture demonstration is presented for comparing titration curves. A plot of pH vs volume of strong base is produced by connecting the external output of a pH meter to a strip recorder. Thus, pH is recorded as a function of time. (BB)

Gilbert, George L., Ed.

1979-01-01

406

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.

1983-01-01

407

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.

1978-01-01

408

A mechanistic description of Ni and Zn sorption on Na-montmorillonite Part I: Titration and sorption measurements  

Microsoft Academic Search

In this paper experimental investigations into the acid\\/base titration characteristics of Na-montmorillonite and the sorption behaviour of Ni and Zn under a wide variety of conditions are presented. From these measurements the dominant sorption mechanisms could be deduced. In the following paper (Bradbury and Baeyens, 1997) the titration and sorption data are analysed to determine the parameters in cation exchange

Bart Baeyens; Michael H. Bradbury

1997-01-01

409

Theoretical autophotogrammetry. I - The method of the photometric potential  

NASA Technical Reports Server (NTRS)

The present work presents preliminary efforts at a mathematical formulation of a photogrammetric method suitable for computerized processing. A theory is derived for the extraction of surface topography from stereometric pairs of photographs. The theory can be applied to either convergent or near-orthographic-projection stereo. Scene brightness is treated as a scalar function defined on a general surface embedded in ordinary three-dimensional space (the actual topography). Correspondence of points is based on adjustments leading to photometric equivalence, while the adjustments are based on the local value of the photometric gradient.

Wildey, R. L.

1973-01-01

410

A photometric study of the counterglow from space.  

NASA Technical Reports Server (NTRS)

Photometric observations of the region of the counterglow (Gegenschein) made from OSO-6 are examined. The observations were made during the September to October 1970 period when the counterglow was between the Milky Way arms at a relatively high (negative) galactic latitude. The lines of sight included a slice across the antisun region at an inclination of 48 degrees to the ecliptic. A comparison is made between the photometric gradients as measured from the spacecraft and similar gradients deduced from ground-based observations.

Roach, F. E.; Carroll, B.; Aller, L. H.; Roach, J. R.

1973-01-01

411

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

1998-10-26

412

Preliminary Photometric Solutions of Two EA Type Binaries in ? Centauri  

NASA Astrophysics Data System (ADS)

We present the preliminary results of photometric solutions of two EA type binaries (V192 and V239) in the southern globular cluster ? Cen. This is the first time to obtain photometric solutions of the two binaries. From our preliminary analysis we get that both the two binaries have very low mass-ratio, 0.139 for V192 and 0.085 for V239. Because of the low mass-ratio their secondary components are both very special objects and they are possibly horizontal branch stars. But they need more observation.

Li, K.; Qian, S.; Leung, K.

2011-12-01

413

SHARDS: AN OPTICAL SPECTRO-PHOTOMETRIC SURVEY OF DISTANT GALAXIES  

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

2013-01-01

414

Simultaneous Estimation of Photometric Redshifts and SED Parameters: Improved Techniques and a Realistic Error Budget  

NASA Astrophysics Data System (ADS)

We present the results of recent work seeking to improve the accuracy of joint galaxy photometric redshift estimation and spectral energy distribution (SED) fitting. By simulating different sources of uncorrected systematic errors, we show that if the uncertainties on the photometric redshifts are estimated correctly, so are those on the other SED fitting parameters, such as stellar mass, stellar age, and dust reddening. Furthermore, we find that if the redshift uncertainties are over(under)-estimated, the uncertainties in SED parameters will be over(under)-estimated by similar amounts. These results hold even in the presence of severe systematics and provide, for the first time, a mechanism to validate the uncertainties on these parameters via comparison with spectroscopic redshifts. We show that template incompleteness, a major cause of inaccuracy in this process, is ``flagged" by a large fraction of outliers in redshift and that it can be corrected by using more flexible stellar population models. We propose a new technique (annealing) to re-calibrate the joint uncertainties in the photo-z and SED fitting parameters without compromising the performance of the SED fitting + photo-z estimation. This procedure provides a consistent estimation of the multidimensional probability distribution function in SED fitting + z parameter space, including all correlations.

Acquaviva, Viviana; Raichoor, Anand; Gawiser, Eric J.

2015-01-01

415

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

PubMed

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

2014-01-01

416

THE FUTURE OF PHOTOMETRIC, SPECTROPHOTOMETRIC AND POLARIMETRIC STANDARDIZATION  

E-print Network

Stratospheric Observatory for Infrared Astronomy/Universities Space Research Association, NASA Ames Research Series, Vol. 999, 2007 C. Sterken Steps Toward a Common Near-Infrared Photometric System A. T. Tokunaga Institute for Astronomy, University of Hawaii, 2680 Woodlawn Dr., Honolulu, HI 96822 W. D. Vacca

Tokunaga, Alan

417

Photometric Detection of Extrasolar Planets by the Transit Method  

E-print Network

Photometric Detection of Extrasolar Planets by the Transit Method Hans­J¨org Deeg Instituto de Astrofisica de Canarias, E­38200 La Laguna, Tenerife, Spain Abstract. The transit method for the detection of extrasolar planets is based on the detection of stellar brightness variations, which result from the transit

Deeg, Hans-Jörg

418

BVRI photometric analysis for the galaxy group NGC 4410  

Microsoft Academic Search

We present a BVRI CCD (Charge Coupled Device) surface photometry analysis of the galaxy group NGC 4410, which contains four galaxies in interaction. Along with our photometric study, we show residual images (after subtracting isophotal models) and unsharp masked images to uncover any hidden structures in this system of galaxies; we have also performed a two-dimensional bulge-disk decomposition for NGC

J. A. Pérez Grana; S. N. Kemp; A. C. Katsiyannis; A. Franco-Balderas; E. de La Fuente; J. Meaburn; H. G. Khosroshahi

2008-01-01

419

Accretion disc evolution in DW Ursae Majoris: A photometric study  

Microsoft Academic Search

We present an analysis of CCD photometric observations of the eclipsing novalike cataclysmic variable DW UMa obtained in two different luminosity states: high and intermediate. The star presents eclipses with very different depth: ˜1.2 mag in the high and ˜3.4 mag in the intermediate state. Eclipse mapping reveals that this difference is almost entirely due to the changes in the

V. Stanishev; Z. Kraicheva; H. M. J. Boffin; V. Genkov; C. Papadaki; S. Carpano

2004-01-01

420

Photometric study of the young open cluster NGC 3293  

Microsoft Academic Search

Deep and extensive CCD photometric observations at UBV(RI)_CHalpha were carried out in the area of the open cluster NGC 3293. The new data set allows to see the entire cluster sequence down to MV ~ +4.5, revealing that stars with MV < -2 are evolving off the main sequence; stars with -2 < MV < +2 are located on the

Gustavo Baume; R. A. Vázquez; Giovanni Carraro; Alejandro Feinstein

2003-01-01

421

Type Ia SN1999cw: photometric and spectroscopic study  

E-print Network

The preliminary analysis of the optical data of SN1999cw show that this object has the photometric and spectroscopic behavior of a Type Ia supernova similar to SN1991T, reaching an apparent magnitude at maximum B(max)=14.30 and a Delta m_{15}(B)=0.94.

F. Bufano; M. Turatto; S. Benetti; A. Harutyunyan; N. Elias-Rosa; E. Cappellaro; .

2004-10-20

422

A photometric study of heat flow at the solar photosphere  

Microsoft Academic Search

Results of a general survey of photospheric heat flow on scales between granulation and global scale convection are presented. Photometric rasters in the visible continuum show a prominent mottle pattern whose scale and morphology resemble the CaK chromospheric network, but the pattern's correlation with photospheric magnetic fields is too low and its lifetime of 5-10 minutes is too short to

P. Foukal; L. Fowler

1984-01-01

423

Remote sensing photometric studies of Mars in 1971.  

NASA Technical Reports Server (NTRS)

Evaluation of the photometric Mars observations performed during the exceptionally favorable opposition of this planet in 1971. The techniques employed included conventional photography, multichannel spot photometry, dual channel area scanning, and image digitizing. Among the results obtained, there are indications that the Minnaert function is generally valid for the bright areas of Mars.

Boyce, P.

1973-01-01

424

Recovering Photometric Properties Of Architectural Scenes From Photographs  

E-print Network

- plain the measured values in the various photographs of the scene. The lighting models include of generating photore- alistic renderings of real architectural scenes under novel lighting conditions has beenRecovering Photometric Properties Of Architectural Scenes From Photographs Yizhou Yu Jitendra Malik

Malik, Jitendra

425

Recovering Photometric Properties Of Architectural Scenes From Photographs  

E-print Network

­ plain the measured values in the various photographs of the scene. The lighting models include of generating photore­ alistic renderings of real architectural scenes under novel lighting conditions has beenRecovering Photometric Properties Of Architectural Scenes From Photographs Yizhou Yu Jitendra Malik

Yu, Yizhou

426

Extremely Late-Time Photometric Observations of SN 2011fe  

NASA Astrophysics Data System (ADS)

We have obtained 2 epochs of extremely late-time optical and infrared (IR) photometric observations of the nearby (6.4 Mpc; Shappee & Stanek 2011) Type Ia Supernova SN2011fe (Nugent et al., ATEL #3581) with WFC3 onboard HST under the Cycle 22 program GO-13737 (PI Shappee).

Shappee, B. J.; Stanek, K. Z.; Kochanek, C. S.; Gerke, J. R.; Garnavich, P.

2015-04-01

427

10.1117/2.1201102.003507 Photometric design of  

E-print Network

. Traditional broad-emitter phosphors are made by incorporating a combination of rare earth ions into ceramic of the human eye. LER values rarely go above 300lm/Wopt. The correlated color temperature (CCT) is another to be tuned. However, the complex relationship between the photometric figures-of-merit makes it difficult

Demir, Hilmi Volkan

428

PROTOTYPE CORRELATION MASK FLAME PHOTOMETRIC DETECTOR FOR MEASURING SULFUR DIOXIDE  

EPA Science Inventory

A prototype flame photometric detector system (FPD) to measure gaseous sulfur compounds was fabricated using a previously developed correlation mask optical system and a new flame housing. Also, a new burner for the FPD system was optimized to view the excited molecular sulfur em...

429

A Computer Program to Analyze Photometric Data on Asteroids  

NASA Astrophysics Data System (ADS)

A description is given of a computer program written in BASIC designed to yield photometric parameters of asteroids. Using the least squares method, the program computes the asteroids' phase coefficient and absolute magnitude. Also derived are its albedo, multiple scattering factor, and diameter. For each night of observation, the mean magnitude, the correction factor, the corrected magnitude, and the phase angle are calculated.

Cunningham, Clifford J.; Kaitting, Murray K.

1983-06-01

430

A photometric investigation of ultra-efficient LEDs with high color rendering index and high  

E-print Network

@bilkent.edu.tr Abstract: We report a photometric study of ultra-efficient light emitting diodes (LEDs) that exhibitA photometric investigation of ultra-efficient LEDs with high color rendering index and high

Demir, Hilmi Volkan

431

21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Discrete photometric chemistry analyzer for clinical use. 862.2160...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical... § 862.2160 Discrete photometric chemistry analyzer for clinical use. (a)...

2011-04-01

432

21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Discrete photometric chemistry analyzer for clinical use. 862.2160...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical... § 862.2160 Discrete photometric chemistry analyzer for clinical use. (a)...

2013-04-01

433

21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Discrete photometric chemistry analyzer for clinical use. 862.2160...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical... § 862.2160 Discrete photometric chemistry analyzer for clinical use. (a)...

2010-04-01

434

21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 false Discrete photometric chemistry analyzer for clinical use. 862.2160...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical... § 862.2160 Discrete photometric chemistry analyzer for clinical use. (a)...

2014-04-01

435

21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Discrete photometric chemistry analyzer for clinical use. 862.2160...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical... § 862.2160 Discrete photometric chemistry analyzer for clinical use. (a)...

2012-04-01

436

EXPLORING THE VARIABLE SKY WITH LINEAR. I. PHOTOMETRIC RECALIBRATION WITH THE SLOAN DIGITAL SKY SURVEY  

E-print Network

We describe photometric recalibration of data obtained by the asteroid survey LINEAR. Although LINEAR was designed for astrometric discovery of moving objects, the data set described here contains over 5 billion photometric ...

Sesar, Branimir

437

Photometric and positional accuracy of the PDS Bonn in view of astronomical requirements  

NASA Technical Reports Server (NTRS)

The photometric and positional accuracy of a microdensitometer is examined. A calibrating plate with different density areas available is used to determine photometric accuracy. Position accuracy is evaluated by multiple scans of sharp edges and analyzed statistically.

Becker, H. J.

1984-01-01

438

A sounding rocket spectroheliometer for photometric studies at extreme ultraviolet wavelengths. [Skylab Apollo Telescope Mount calibration  

NASA Technical Reports Server (NTRS)

Construction and mode of operation are described for a sounding rocket spectroheliometer used to establish the sensitivity of the EUV spectroheliometer on the Skylab Apollo Telescope Mount (ATM). The sounding rocket instrument was calibrated immediately before and after two flights and the calibration was transferred when the rocket and ATM instruments simultaneously measured the average intensity emitted by a quiet area of the solar disk. Descriptions are presented for the payload assembly and flight sequence, the optical system (telescope, spectrometer, and pointing reference camera), the vacuum pumping system, and the instrument electronics. Results obtained from the two flights in August and December 1973 are discussed, which included unambiguous determinations of the absolute intensity emitted by a region of the quiet solar disk over the wavelength range from 1350 to 300 A on two separate occasions and the establishment of photometric accuracy to that of laboratory calibration procedures.

Timothy, J. G.; Chambers, R. M.; Dentremont, A. M.; Lanham, N. W.; Reeves, E. M.

1975-01-01

439

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.

1957-01-01

440

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.

2007-05-01

441

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.

2014-11-01

442

Photometric Reverberation Mapping using a Meter-class Telescope  

NASA Astrophysics Data System (ADS)

For the past several decades, mass estimates for supermassive black holes hosted by active galactic nuclei (AGNs) have been made using the reverberation mapping (RM) technique. This methodology has produced consistent results and has been used to establish several relations that link the characteristics of the host galaxy to the mass of the central black hole. Despite this success, there are less than 50 AGNs with black hole masses derived from RM. This low number is generally attributed to the difficulties in coordinating large blocks of telescope time for making the simultaneous photometric and spectroscopic observations. In addition, the spectroscopic observations generally require several months of nightly observations with moderate to large size telescopes.We have made photometric observations of several AGNs in selected filters in order to evaluate a photometric methodology for determining the lag time between the variations observed in the continuum and the response signal that is seen coming from the broad-line region (BLR) gas. This time delay represents the mean light travel time to the BLR, and is therefore a measurement of the mean BLR radius. In traditional RM campaigns, this time lag is combined with a measure of the width of the broad line to determine the velocity of the gas and then make a virial estimate of the black hole mass. We investigate results obtained using photometric time lags and a single epoch spectroscopic measurement of the line width in order to estimate the mass of the central black hole.We present results from our photometric observations of several target AGNs made with the West Mountain Observatory 0.9 m reflector during the spring and summer of 2014.This research was supported by the College of Physical and Mathematical Sciences at Brigham Young University as well as through a fellowship from the NASA Rocky Mountain Space Grant Consortium.

Carroll, Carla June; Joner, Michael D.

2015-01-01

443

PHOTOMETRIC SUPERNOVA COSMOLOGY WITH BEAMS AND SDSS-II  

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: rhlozek@astro.princeton.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

2012-06-20

444

ULTRACOMPACT DWARF GALAXIES IN ABELL 1689: A PHOTOMETRIC STUDY WITH THE ADVANCED CAMERA FOR SURVEYS  

E-print Network

ULTRACOMPACT DWARF GALAXIES IN ABELL 1689: A PHOTOMETRIC STUDY WITH THE ADVANCED CAMERA FOR SURVEYS from Bayesian photometric redshifts. We find 160 UCD candidates with 22 mag that about 100 of these are cluster members, based on their spatial distribution and photometric redshifts

445

CD-monitored redox titration of the Rieske Fe-S protein of Rhodobacter sphaeroides: pH dependence of the midpoint potential  

E-print Network

CD-monitored redox titration of the Rieske Fe-S protein of Rhodobacter sphaeroides: pH dependence.5 in the range of titration, or by two pK values, pKI = 7.6 and pKP = 9.8. Similar titrations and pK values were

Crofts, Antony R.

446

Radial Velocity Variations of Photometrically Quiet, Chromospherically Inactive Kepler Stars: A Link between RV Jitter and Photometric Flicker  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

447

Analysis of creams. II. Quantitative determination of drugs in creams by titration in non-aqueous solvents.  

PubMed

The possibilities for the determination of active components in creams by acid-base titrations in non-aqueous solvents were investigated. Interference by cream-base components with the titration of weak organic bases and their halides with perchloric acid in acetic acid, and with the titration of weak acids with tetrabutylammonium hydroxide in N,N-dimethylformamide were studied. It appeared to be possible to determine alkaloid halides, salicylic acid, hexachlorophene and methyl salicylate without previous clean-up of the cream samples. PMID:6280125

Van de Vaart, F J; Hulshoff, A; Indemans, A W

1982-02-19

448

Influence of kinetics on the determination of the surface reactivity of oxide suspensions by acid-base titration.  

PubMed

The effect of acid-base titration protocol and speed on pH measurement and surface charge calculation was studied on suspensions of gamma-alumina, hematite, goethite, and silica, whose size and porosity have been well characterized. The titration protocol has an important effect on surface charge calculation as well as on acid-base constants obtained by fitting of the titration curves. Variations of pH versus time after addition of acid or base to the suspension were interpreted as diffusion processes. Resulting apparent diffusion coefficients depend on the nature of the oxide and on its porosity. PMID:16949092

Duc, M; Adekola, F; Lefèvre, G; Fédoroff, M

2006-11-01

449

Volumetric determination of uranium titanous sulfate as reductant before oxidimetric titration  

USGS Publications Warehouse

Need for a more rapid volumetric method for the routine determination of uranium in uranium-rich materials has led to the development of a method that uses titanous sulfate as a reductant before oxidimetric titration. Separation of the hydrogen sulfide group is not necessary. Interfering elements precipitated by cupferron are removed by automatic filtrations made simultaneously rather than by the longer chloroform extraction method. Uranium is reduced from VI to IV by addition of an excess of titanous sulfate solution, cupric ion serving as an indicator by forming red metallic copper when reduction is complete. The copper is reoxidized by addition of mercuric perchlorate. The reduced uranium is then determined by addition of excess ferric sulfate and titration with ceric sulfate. The method has proved to be rapid, accurate, and economical.

Wahlberg, J.S.; Skinner, D.L.; Rader, L.F., Jr.

1957-01-01

450

The binding of aluminum to mugineic acid and related compounds as studied by potentiometric titration.  

PubMed

The phytosiderophores, mugineic acid (MA) and epi-hydroxymugineic acid (HMA), together with a related compound, nicotianamine (NA), were investigated for their ability to bind Al(III). Potentiometric titration analysis demonstrated that MA and HMA bind Al(III), in contrast to NA which does not under normal physiological conditions. With MA and HMA, in addition to the Al complex (AlL), the protonated (AlLH) and deprotonated (AlLH(-1)) complexes were identified from an analysis of titration curves, where L denotes the phytosiderophore form in which all the carboxylate functions are ionized. The equilibrium formation constants of the Al(III) phytosiderophore complexes are much smaller than those of the corresponding Fe(III) complexes. The higher selectivity of phytosiderophores for Fe(III) over Al(III) facilitates Fe(III) acquisition in alkaline conditions where free Al(III) levels are higher than free Fe(III) levels. PMID:21350950

Yoshimura, Etsuro; Kohdr, Hicham; Mori, Satoshi; Hider, Robert C

2011-08-01

451

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.

2007-12-01

452

The predictive value of Muller's maneuvre for CPAP titration in OSAHS patients.  

PubMed

To investigate the role of awake upper airways (UA) endoscopy assessment as a parameter of prediction for CPAP titration in OSAHS patient therapy. Retrospective analysis of UA endoscopic assessment with Mueller's maneuvre and the application of the nose oropharynx hypopharynx score (NOHs) was conducted to obtain a numeric score representing the grade of severity of UA obstruction. Other commonly used predictive parameters for CPAP titration were also included in the study: anthropometric [BMI, neck circumference (NC)] and polysomnographic parameters (AHI, ODI). 3 groups of patients were identified: (1) 67/90 patients requiring intermediate CPAP values, (2) 13/90 patients requiring high CPAP values, and (3) 10/90 patients requiring low pressure values. BMI (p = 0.0013) was the only monitored parameter to show significant statistical value as a CPAP titration predictor. However, higher values of anthropometric parameters (NOHs ?9, BMI >35, NC >45) showed a sensitivity of 69.2% as a single parameter and 76.9% as combined parameters, and specificity between 66.2 and 72.7% as a single parameter and 43.4% as combined parameters, unequivocally identifying patients requiring high therapeutic CPAP value. A lower cut-off of anthropometric parameters (NOHs ?6, BMI ?29, NC <42) showed sensitivity between 40 and 60% as a single parameter and of 90% as combined parameters, and specificity between 68.7 and 80.2% as a single parameter which increased to 93.7% as combined parameters, identifying patients requiring a low therapeutic CPAP value. The results show that anthropometric and polygraphic parameters have no significant independent predictive value for CPAP titration, with the exception of BMI. However, anthropometric parameters showed good levels of sensitivity and specificity in OSAHS patients requiring high or low levels of CPAP therapy. PMID:23463348

Bosi, Marcello; De Vito, Andrea; Vicini, Claudio; Poletti, Venerino

2013-08-01

453

31P NMR and isothermal titration calorimetry studies on polyoxomolybdates-catalyzed hydrolysis of ATP  

Microsoft Academic Search

ATP hydrolysis in the presence of polyoxomolybdates at pH levels of 6, 4, and 2 has been investigated with a help of high pressure liquid chromatography (HPLC) analyses, 31P- and 1H NMR measurements, and isothermal titration calorimetry (ITC). The polyoxomolybdates-induced ATP-hydrolysis proceeded satisfactorily in pH<6 media at 20°C with an optimum pH level of 4, while it was significantly depressed

Eri Ishikawa; Toshihiro Yamase

2006-01-01

454

Determination of the cyclodextrin inclusion constant with the constant current coulometric titration method.  

PubMed

With fluorometry this paper has proved that alpha-cyclodextrin (CD) and gamma-CD do not form inclusion complexes with procaine, while beta-CD and HP-beta-CD do. Their molar ratios are demonstrated both 1:1 with the equimolar variation method. The constant current coulometric titration method (CCCT) is first proposed and applied in the determination of the CD inclusion constant. To compare with this method, the fluorescence experiment has been done with the satisfactory results. PMID:18967691

Gu, J; Pan, J

1999-08-23

455

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)

1994-07-01

456

Hydrogen-Aluminum Clays: A Third Buffer Range Appearing in Potentiometric Titration  

Microsoft Academic Search

Wyoming montmorillonite (bentonite, particles 2 to 0.2 mu in diameter) treated with hydrogen-ion-saturated resin shows, on titration in 1N KNO3 with NaOH by a continuously recording instrument, a third buffer range between pH 5.5 and 7.6 in addition to the first range where exchangeable hydronium is neutralized and the second range where a reaction with exchangeable aluminohexahydronium, Al(OH2)6{}3+, occurs. The

U. Schwertmann; M. L. Jackson

1963-01-01

457

Reduction of sample volume and waste generation in acid/base titrations using microelectrodes  

SciTech Connect

The Analytical Development Section (ADS) has developed microelectrode methods for use with pH titrations and pH determinations. These microelectrode methods offer increased sensitivity and enable analyses to be done with smaller sample and buffer volumes than are used with standard size electrodes. This report establishes the technical validity of the methods and describes the application of these methods to decreased detection limits, decreased waste generation, and decreased radiation exposure.

Ekechukwu, A.A. [Westinghouse Savannah River Company, AIKEN, SC (United States)

1996-03-22

458

Study of Some Physicochemical Properties of Pillared Montmorillonites: AcidBase Potentiometric Titrations and Electrophoretic Measurements  

Microsoft Academic Search

The surface charges and the zeta potential ofa Na-montmorillonite (Na-mont) and two pillared montmorillonite (MP1 and MP2) samples with different aluminum contents were determined by poten- tiometric titrations and electrophoretic measurements. At pH > 9 the two pillared montmorillonite sam- ples showed zeta potentials similar to those of Na-mont, but at pH <8, the negative zeta potential shifted to lower

Marcelo J. Avena; RAOL CABROL; CARLOS P. DE PAULI

1990-01-01

459

Persistence length of carboxymethyl cellulose as evaluated from size exclusion chromatography and potentiometric titrations  

Microsoft Academic Search

The intrinsic persistence length of carboxymethyl cellulose (CMC) is determined by size exclusion chromatography in combination with multiangle laser light scattering (SEC-MALLS) as well as from potentiometric titrations. Samples with degree of substitution (ds) ranging from 0.75 to 1.25 were investigated. The relation between molar mass M and radius of gyration Rg as obtained by SEC-MALLS is determined in 0.02,

C. W. Hoogendam; A. de Keizer; M. A. Cohen Stuart; B. H. Bijsterbosch; J. A. M. Smit; Dijk van J. A. P. P; Horst van der P. M; J. G. Batelaan

1998-01-01

460

Thermodynamic dissociation constants of codeine, ethylmorphine and homatropine by regression analysis of potentiometric titration data  

Microsoft Academic Search

Concentration and mixed dissociation constant(s) of three drug acids HJL, codeine, ethylmorphine and homatropine, at various ionic strengths I in the range of 0.03–0.81 have been determined with the use of regression analysis of potentiometric titration data when common parameters (pKa,j, j=1,…,J), and group parameters (E0?, L0, HT) are simultaneously refined. Reliability of the dissociation constant(s) should be proven because

Milan Meloun; Marta Pluha?ová

2000-01-01

461

Characterization of electrostatic binding sites of extracellular polymers by linear programming analysis of titration data  

Microsoft Academic Search

Electrostatic binding sites of extracellular poly- meric substances (EPS) were characterized from titration data using linear programming analysis. Test results for three synthetic solutions of given solutes comprising amino, carboxyl, and phenolic groups indicated that this method was able to identify the electrostatic binding sites. For the six sites with pKa between 3 and 10, the estimated pKa deviated 0.11

Hong Liu; Herbert H. P. Fang

2002-01-01

462

Titration of chiral kink sites on Cu(6 4 3) using iodine adsorption  

E-print Network

Titration of chiral kink sites on Cu(6 4 3) using iodine adsorption Preeti Kamakoti a,b , Joshua have been used to probe the site preferences of adsorbed iodine atoms on Cu surfaces. DFT calculations are presented for iodine adsorption on Cu(1 1 1), Cu(1 0 0), Cu(2 2 1), Cu(5 3 3), Cu(5 3 1), and Cu(6 4 3

Gellman, Andrew J.

463

Comparison of ozone determinations by ultraviolet photometry and gas-phase titration  

NASA Technical Reports Server (NTRS)

A comparison of ozone determinations based on ultraviolet absorption photometry and gas-phase titration (GPT) shows good agreement between the two methods. Together with other results, these findings indicate that three candidate reference methods for ozone, UV photometry, IR photometry, and GPT are in substantial agreement. However, the GPT method is not recommended for routine use by air pollution agencies for calibration of ozone monitors because of susceptibility to experimental error.

Demore, W. B.; Patapoff, M.

1976-01-01

464

Revisiting the streptavidin-biotin binding by using an aptamer and displacement isothermal calorimetry titration.  

PubMed

The association constant of a well-known streptavidin-biotin binding has only been inferred from separately measured kinetic parameters. In a single experiment, we obtained Ka 1??×??10(12) ?M(-1) by using a streptavidin-binding aptamer and ligand-displacement isothermal titration calorimetry. This study explores the challenges of determining thermodynamic parameters and the derived equilibrium binding affinity of tight ligand-receptor binding. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25615849

Kuo, Tai-Chih; Tsai, Ching-Wei; Lee, Peng-Chen; Chen, Wen-Yih

2015-03-01

465

Acid-base titrations using microfluidic paper-based analytical devices.  

PubMed

Rapid and simple acid-base titration was accomplished using a novel microfluidic paper-based analytical device (?PAD). The ?PAD was fabricated by wax printing and consisted of ten reservoirs for reaction and detection. The reaction reservoirs contained various amounts of a primary standard substance, potassium hydrogen phthalate (KHPth), whereas a constant amount of phenolphthalein was added to all the detection reservoirs. A sample solution containing NaOH was dropped onto the center of the ?PAD and was allowed to spread to the reaction reservoirs where the KHPth neutralized it. When the amount of NaOH exceeded that of the KHPth in the reaction reservoirs, unneutralized hydroxide ion penetrated the detection reservoirs, resulting in a color reaction from the phenolphthalein. Therefore, the number of the detection reservoirs with no color change determined the concentration of the NaOH in the sample solution. The titration was completed within 1 min by visually determining the end point, which required neither instrumentation nor software. The volumes of the KHPth and phenolphthalein solutions added to the corresponding reservoirs were optimized to obtain reproducible and accurate results for the concentration of NaOH. The ?PADs determined the concentration of NaOH at orders of magnitude ranging from 0.01 to 1 M. An acid sample, HCl, was also determined using Na2CO3 as a primary standard substance instead of KHPth. Furthermore, the ?PAD was applicable to the titrations of nitric acid, sulfuric acid, acetic acid, and ammonia solutions. The ?PADs were stable for more than 1 month when stored in darkness at room temperature, although this was reduced to only 5 days under daylight conditions. The analysis of acidic hot spring water was also demonstrated in the field using the ?PAD, and the results agreed well with those obtained by classic acid-base titration. PMID:25423320

Karita, Shingo; Kaneta, Takashi

2014-12-16

466

What do acid-base titrations of live bacteria tell us? A preliminary assessment  

Microsoft Academic Search

To gain insight into the non-equilibrium processes that affect the titration curves of bacteria, we performed pH stat experiments with suspensions of live cells of the Gram-negative bacterium Shewanella putrefaciens. The experiments lasted for 5 hours, during which acid or base addition was monitored. Periodically, the electrophoretic mobility of the cells, as well as the buffer capacity and the concentrations

Jacqueline Claessens; Thilo Behrends; Philippe Van Cappellen

2004-01-01

467

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

1988-01-01

468

Determining surface areas of marine alga cells by acid-base titration method  

Microsoft Academic Search

A new method for determining the surface area of living marine alga cells was described. The method uses acid-base titration to measure the surface acid\\/base amount on the surface of alga cells and uses the BET (Brunauer, Emmett, and Teller) equation to estimate the maximum surface acid\\/base amount, assuming that hydrous cell walls have carbohydrates or other structural compounds which

Xiulin Wang; Yanjun Ma; Yuenlan Su

1997-01-01

469

Coulometric generation of acids and bases for acid–base titrations in non-aqueous solvents  

Microsoft Academic Search

A literature review of compounds which on electro-oxidation or reduction produce a strong acid or strong base in non-aqueous solvents is presented in this paper. The application of these compounds as anodic or cathodic depolarizers for coulometric titrations of acids, bases and salts as well as for the study of acid–base equilibria in non-aqueous solvents is also covered.

R. P. Mihajlovi?; Lj. N. Jakši?; R. M. Džudovi?

2006-01-01

470

Single-strand DNA translation initiation step analyzed by Isothermal Titration Calorimetry  

Microsoft Academic Search

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

Luminita Damian; Claire Marty-Detraves; Mathias Winterhalter; Didier Fournier; Laurent Paquereau

2009-01-01

471

High polyphenol oxidase activity and low titratable acidity in browning bamboo tissue culture  

Microsoft Academic Search

Summary  Tissue browning that frequently results in the early death of bamboo shoots in vitro correlated directly with polyphenol oxidase (PPO, EC 1.10.3.1) activity and inversely with titratable acidity. It was unrelated\\u000a to the level of endogenous phenols. During the course of culture, timing of PPO activity paralleled that of explant browning.\\u000a Browning was highest among shoots cultured in a medium

Li-Chun Huang; Ya-Lin Lee; Bau-Lian Huang; Ching-I Kuo; Jei-Fu Shaw

2002-01-01

472

THEORETICAL ANALYSIS OF RELATIONSHIPS BETWEEN COMPOSITION, pH, AND TITRATABLE ACIDITY OF PEACH FRUIT  

Microsoft Academic Search

The chemical reactions that determine pH and titration curve of peach (Prunus persica L. Batsch) fruit flesh tissue have been modeled. Fruit pulp pH is computed as the result of acid\\/base reactions between organic acids, amino acids, and phosphate derivatives, and their respective salts. Amino acids and phosphate derivatives are taken into account as if they comprised asparagine and phosphoric

Philippe Lobit; Patrick Soing; Michel Génard; Robert Habib

2002-01-01

473

THE PHOTOMETRIC CLASSIFICATION SERVER FOR Pan-STARRS1  

SciTech Connect

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

Saglia, R. P.; Bender, R.; Seitz, S.; Senger, R.; Snigula, J.; Phleps, S.; Wilman, D. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, 85741 Garching (Germany); Tonry, J. L.; Burgett, W. S.; Chambers, K. C.; Heasley, J. N.; Kaiser, N.; Magnier, E. A.; Morgan, J. S. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Greisel, N. [University Observatory Munich, Ludwig-Maximilians Universitaet, Scheinerstrasse 1, 81679 Munich (Germany); Bailer-Jones, C. A. L.; Klement, R. J.; Rix, H.-W.; Smith, K. [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Green, P. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); and others

2012-02-20

474

Photometric Imaging of the Moon from the Robotic Lunar Observatory  

NASA Astrophysics Data System (ADS)

As part of the calibration program for the NASA Earth Observing System (part of NASA's Earth Science Enterprise), the U.S. Geological Survey operates the Robotic Lunar Observatory (ROLO). The ROLO project is designed to produce a photometric model of the nearside lunar surface for all phase and libration angles visible from Flagstaff [2]. Goals for this photometric model are 2.5 % absolute and 1.0% relative uncertainty. Although the model is principally intended to produce radiance images of the Moon for use in calibration of Earth-orbiting spacecraft, the ROLO data and model will also provide important information for studies of the lunar soil. Instrumentation: An astronomical observatory dedicated to the radiometry of the Moon has been constructed on the campus of the U.S. Geological Survey Flagstaff Field Station in Arizona. Two separate camera systems are attached to a single telescope mount and boresighted to the same pointing direction. The visible/near infrared (VNIR) camera uses a 512 x 512 pixel CCD and 23 intermediate width interference filters for wavelength selection. The shortwave infrared (SWIR) camera uses a 256 x 256 pixel cooled-HgCdTe infrared array and nine intermediate-width interference filters. Table I and Fig. I provide information on the instrumental passbands. Separate 20-cm-diameter Ritchey-Cretien telescopes are provided for the two cameras. The optics are designed to image the entire Moon within each camera's field of view, resulting in instrument pixel scales of 4 and 8 arcsec /pixel (about 7.4 and 15 km/pixel for the sub-Earth point on the Moon) for VNIR and SWIR respectively. Detailed information on the instrumentation can be found in Anderson et al. Observations: Routine imaging has been in progress since late 1995 for VNIR and late 1997 for SWIR, and is expected to continue through at least 2002. ROLO observes the Moon every clear night between the first and last quarter phases of the moon. On such nights, the Moon is imaged through all 32 filters at half-hour intervals during the time that the Moon is above the 60 deg. zenith angle. Observations of standard stars to measure atmospheric extinction and detector responsivity drifts occupy the remainder of the nighttime. Measurements of the dark current and detector bias levels are made during the dusk and dawn periods for VNIR and throughout the night for SWIR. Flat field corrections and absolute radiance calibrations are provided through observations of a Spectralon plate illuminated by a NIST-traceable 1000 W FEL lamp. Raw data are converted to ISIS cubes and stored on CD-ROM. Detailed information on the observing procedure is also found. As the development of data-reduction software for the ROLO project progresses and additional data are accumulated, the raw data are repeatedly processed into a calibrated form. Corrections for instrument response characteristics, photon scattering processes, and atmospheric extinction are applied to the raw lunar images to produce exoatmospheric radiance images of the Moon. These images are then transformed to a fixed selenographic-grid projection designed to accommodate all of the possible viewing geometries of the ROLO telescope. A preliminary discussion of results for the total irradiance of the Moon derived from ROLO VNIR images acquired through April 1998 was published by Kieffer and Anderson. At that time, difficulties in adequately determining the atmospheric extinction limited the accuracy of the derived lunar irradiance values. Significant improvements in the reduction software have been developed since that time and measurement scatter is expected to be reduced to approximately = or <2% for the data-processing run planned for the summer of 1999. As of June 1999 , ROLO has acquired over 2200 cubes of raw Moon images with VNIR and over 1200 cubes with SWIR. By 2002, ROLO expects to have acquired roughly 3500 images of the Moon through each VNIR filter and nearly 3000 images through each SWIR filter, or more than 100,000 absolutely calibrated images of the Moon. These data are used to create p

Anderson, J. M.; Kieffer, H. H.

1999-01-01

475

Prediction of aluminum, uranium, and co-contaminants precipitation and adsorption during titration of acidic sediments.  

PubMed

Batch and column recirculation titration tests were performed with contaminated acidic sediments. A generic geochemical model was developed combining precipitation, cation exchange, and surface complexation reactions to describe the observed pH and metal ion concentrations in experiments with or without the presence of CO2. Experimental results showed a slow pH increase due to strong buffering by Al hydrolysis and precipitation and CO2 uptake. The cation concentrations generally decreased at higher pH than those observed in previous tests without CO2. Using amorphous Al(OH)3 and basaluminite precipitation reactions and a cation exchange selectivity coefficient K(Na\\Al) of 0.3, the model approximately described the observed (1) pH titration curve, (2) Ca, Mg, and Mn concentration by cation exchange, and (3) U concentrations by surface complexation with Fe hydroxides at pH < 5 and with liebigite (Ca2UO2(CO3)3·10H2O) precipitation at pH > 5. The model indicated that the formation of aqueous carbonate complexes and competition with carbonate for surface sites could inhibit U and Ni adsorption and precipitation. Our results suggested that the uncertainty in basaluminite solubility is an important source of prediction uncertainty and ignoring labile solid phase Al underestimates the base requirement in titration of acidic sediments. PMID:23641798

Tang, Guoping; Luo, Wensui; Watson, David B; Brooks, Scott C; Gu, Baohua

2013-06-01

476

Titration of biologically active amyloid-? seeds in a transgenic mouse model of Alzheimer's disease.  

PubMed

Experimental evidence in animal models suggests that misfolded Amyloid-? (A?) spreads in disease following a prion-like mechanism. Several properties characteristics of infectious prions have been shown for the induction of A? aggregates. However, a detailed titration of A? misfolding transmissibility and estimation of the minimum concentration of biologically active A? seeds able to accelerate pathological changes has not yet been performed. In this study, brain extracts from old tg2576 animals were serially diluted and intra-cerebrally injected into young subjects from the same transgenic line. Animals were sacrificed several months after treatment and brain slices were analyzed for amyloid pathology. We observed that administration of misfolded A? was able to significantly accelerate amyloid deposition in young mice, even when the original sample was diluted a million times. The titration curve obtained in this experiment was compared to the natural A? load spontaneously accumulated by these mice overtime. Our findings suggest that administration of the largest dose of A? seeds led to an acceleration of pathology equivalent to over a year. These results show that active A? seeds present in the brain can seed amyloidosis in a titratable manner, similarly as observed for infectious prions. PMID:25879692

Morales, Rodrigo; Bravo-Alegria, Javiera; Duran-Aniotz, Claudia; Soto, Claudio

2015-01-01

477

Protein-salt binding data from potentiometric titrations of lysozyme in aqueous solutions containing KCl  

SciTech Connect

An existing method for potentiometric titrations of proteins was improved, tested and applied to titrations of the enzyme hen-egg-white lysozyme in aqueous solutions containing KCl at ionic strengths from 0.1 M to 2.0 M at 25 C. Information about the protein`s net charge dependence on pH and ionic strength were obtained and salt binding numbers for the system were calculated using a linkage concept. For the pH range 2.5--11.5, the net charge slightly but distinctly increases with increasing ionic strength between 0.1 M and 2.0 M. The differences are most distinct in the pH region below 5. Above pH 11.35, the net charge decreases with increasing ionic strength. Preliminary calculation of binding numbers from titration curves at 0.1 M and 1.0 M showed selective association of chloride anions and expulsion of potassium ions at low pH. Ion-binding numbers from this work will be used to evaluate thermodynamic properties and to correlate crystallization or precipitation phase-equilibrium data in terms of a model based on the integral-equation theory of fluids which is currently under development.

Engmann, J.; Blanch, H.W.; Prausnitz, J.M. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.

1997-03-01

478

Titration and characterization of two rhesus-derived SIVmac challenge stocks.  

PubMed

Simian immunodeficiency virus infection of macaques is a model for human immunodeficiency virus infection of humans. In vivo-titrated stocks of SIV are essential for the utilization of this model for vaccine development. The elicitation of anti-human cell antibodies by some vaccines prepared in human cells and the related protective effects of the vaccine produced in human cells suggest a need for new macaque-derived SIV stocks. Here we describe the titration and characterization of two stocks of SIVmac that were produced in primary rhesus macaque cells. The first virus is SIVmac251, isolated from tissues of macaque 251, and the second is a molecular clone designated as SIVmac239. A 50% rhesus monkey infectious dose (MID50) was titrated for each virus stock by intravenous inoculation. An additional five macaques were inoculated with 10 MID50 of the SIVmac251 stock and were followed for disease outcome. All five monkeys developed antigenemia by 14 days postchallenge. Two of the five monkeys developed strong anti-SIV humoral immunity, whereas three developed little or no humoral immunity. As has been observed previously, the rapidity of disease progression correlated with the lack of a strong antibody response. The three animals with low humoral immunity died within 7 months of challenge, with antigenemia, cachexia, hypoproteinemia, hypoalbuminemia, weight loss, and intractable diarrhea, while maintaining their circulating CD4 numbers. One animal died at 1.5 years of more typical simian AIDS. PMID:8198874

Lewis, M G; Bellah, S; McKinnon, K; Yalley-Ogunro, J; Zack, P M; Elkins, W R; Desrosiers, R C; Eddy, G A

1994-02-01

479

[Automatic positive airway pressure in titration and treatment of the obstructive sleep apnea syndrome].  

PubMed

Although continuous airway pressure therapy (CPAP) represents the standard treatment for obstructive sleep apnea syndrome (OSAS) auto-adjusting CPAP (APAP) devices were developed which adapt the treatment pressure to the actual requirement of the patients. The aim of automatic CPAP therapy is to improve the patients' acceptance of positive pressure treatment. The devices react to respiratory flow, flattening of the inspiratory flow contour, snoring, generator speed or the upper airway impedance. In recent years several studies showed that auto CPAP effectively treats respiratory disturbances, improves sleep profile and the self-assessment of the patients equally as good as the gold standard constant CPAP. Moreover, APAP reduces the treatment pressure substantially. Although an improvement of the patient's compliance has not consistently been proven, most patients prefer APAP versus constant CPAP. APAP devices use different algorithms depending on the primary purpose of the application. Therefore, a clear distinction between automatic titration and treatment is of major relevance. While titration devices aim at the finding of one single pressure which is fixed to a constant CPAP device, automatic treatment means the chronic use of APAP at home for optimal adaptation of the treatment pressure to the actual requirements of the patient. A high constant CPAP level, huge pressure variability, insuffici