Asphalt compatibility testing using the automated Heithaus titration test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauli, A.T.

1996-12-31

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

Spectrophotometric Titration of a Mixture of Calcium and Magnesium.

ERIC Educational Resources Information Center

Fulton, Robert; And Others

1986-01-01

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

pH Static Titration: A Quasistatic Approach

ERIC Educational Resources Information Center

Michalowski, Tadeusz; Toporek, Marcin; Rymanowski, Maciej

2007-01-01

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

Surface acid-base behaviors of Chinese loess.

PubMed

Chu, Zhaosheng; Liu, Wenxin; Tang, Hongxiao; Qian, Tianwei; Li, Shushen; Li, Zhentang; Wu, Guibin

2002-08-15

Acid-base titration was applied to investigate the surface acid-base properties of a Chinese loess sample at different ionic strengths. The acidimetric supernatant was regarded as the system blank of titration to correct the influence of particle dissolution on the estimation of proton consumption. The titration behavior of the system blank could be described by the hydrolysis of Al3+ and Si(OH)4 in aqueous solution as well as the production of hydroxyaluminosilicates. The formation of Al-Si species on homogeneous surface sites by hydrous aluminum and silicic acid, released from solid substrate during the acidic titration, was considered in the model description of the back-titration procedure. A surface reaction model was suggested as follows: >SOH<-->SO(-)+H+, pK(a)(int)=3.48-3.98;>SOH+Al(3+)+H4SiO4<-->SOAl(OSi(OH)3(+)+2H+, pK(SC)=3.48-4.04. Two simple surface complexation models accounted for the interfacial structure, i.e., the constant capacitance model (CCM) and the diffuse layer model (DLM), and gave a satisfactory description of the experimental data. Considering the effect of ionic strength on the electrostatic profile at the solid-aqueous interface, the DLM was appropriate at the low concentrations (0.01 and 0.005 mol/L) of background electrolyte (NaNO3 in this study), while the CCM was preferable in the case of high ionic strength (0.1 mol/L).

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

PubMed Central

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

2007-01-01

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

Initiation of Levodopa-Carbidopa Intestinal Gel Infusion Using Telemedicine (Video Communication System) Facilitates Efficient and Well-Accepted Home Titration in Patients with Advanced Parkinson's Disease.

PubMed

Willows, Thomas; Dizdar, Nil; Nyholm, Dag; Widner, Håkan; Grenholm, Peter; Schmiauke, Ursula; Urbom, Anna; Groth, Kristina; Larsson, Jörgen; Permert, Johan; Kjellander, Susanna

2017-01-01

Levodopa-carbidopa intestinal gel (LCIG; Duodopa®) is used for continuous infusion in advanced Parkinson's disease. To achieve optimal effect, the LCIG dose is individually titrated, traditionally conducted during hospitalization in Sweden. However, dose adjustment depends on surrounding conditions, physical activity, and emotional stress, which is why titration at home could be beneficial. Telemedicine (TM) using a video communication system offers alternative titration procedures, allowing LCIG initiation at home. Study objectives were to show the feasibility of TM for LCIG home titration, evaluate resource use, and assess patient, neurologist, and nurse satisfaction. Four clinics enrolled 15 patients to observe efficiency and feasibility of TM-based monitoring. Patient median (range) age was 67 (52-73) years and time since diagnosis was 10 (7-23) years. Median time between LCIG initiation and end of TM-assisted titration was 2.8 (2.0-13.8) days. Median time required for home titration by neurologists, nurses, and patients was (hours:minutes) 1 : 14 (0 : 29-1 : 52), 5 : 49 (2 : 46-10 : 3), and 8 : 53 (4 : 11-14 : 11), respectively. Neurologists and nurses considered this to be less time than required for hospital titration. TM allowed patients 92% free time from start to end of titration. Technical problems associated with TM contacts were rare, mostly related to digital link, and quickly resolved. Patients, neurologists, and nurses were satisfied using TM. No serious adverse events were reported; there was one device complaint (tube occlusion). In this study, TM-assisted LCIG titration at home was resource-efficient, technically feasible, well-accepted and was deemed satisfactory by patients, neurologists, and nurses.

Assessment of two theoretical methods to estimate potentiometric titration curves of peptides: comparison with experiment.

PubMed

Makowska, Joanna; Bagiñska, Katarzyna; Makowski, Mariusz; Jagielska, Anna; Liwo, Adam; Kasprzykowski, Franciszek; Chmurzyñski, Lech; Scheraga, Harold A

2006-03-09

We compared the ability of two theoretical methods of pH-dependent conformational calculations to reproduce experimental potentiometric titration curves of two models of peptides: Ac-K5-NHMe in 95% methanol (MeOH)/5% water mixture and Ac-XX(A)7OO-NH2 (XAO) (where X is diaminobutyric acid, A is alanine, and O is ornithine) in water, methanol (MeOH), and dimethyl sulfoxide (DMSO), respectively. The titration curve of the former was taken from the literature, and the curve of the latter was determined in this work. The first theoretical method involves a conformational search using the electrostatically driven Monte Carlo (EDMC) method with a low-cost energy function (ECEPP/3 plus the SRFOPT surface-solvation model, assumming that all titratable groups are uncharged) and subsequent reevaluation of the free energy at a given pH with the Poisson-Boltzmann equation, considering variable protonation states. In the second procedure, molecular dynamics (MD) simulations are run with the AMBER force field and the generalized Born model of electrostatic solvation, and the protonation states are sampled during constant-pH MD runs. In all three solvents, the first pKa of XAO is strongly downshifted compared to the value for the reference compounds (ethylamine and propylamine, respectively); the water and methanol curves have one, and the DMSO curve has two jumps characteristic of remarkable differences in the dissociation constants of acidic groups. The predicted titration curves of Ac-K5-NHMe are in good agreement with the experimental ones; better agreement is achieved with the MD-based method. The titration curves of XAO in methanol and DMSO, calculated using the MD-based approach, trace the shape of the experimental curves, reproducing the pH jump, while those calculated with the EDMC-based approach and the titration curve in water calculated using the MD-based approach have smooth shapes characteristic of the titration of weak multifunctional acids with small differences between the dissociation constants. Nevertheless, quantitative agreement between theoretically predicted and experimental titration curves is not achieved in all three solvents even with the MD-based approach, which is manifested by a smaller pH range of the calculated titration curves with respect to the experimental curves. The poorer agreement obtained for water than for the nonaqueous solvents suggests a significant role of specific solvation in water, which cannot be accounted for by the mean-field solvation models.

Going Beyond, Going Further: Knives, Forks, and Beer Cans as Potentiometric Sensors.

ERIC Educational Resources Information Center

Selig, Walter S.

1985-01-01

Background information, materials needed, and procedures used are provided for potentiometric fluoride, halide, orthophosphate, and sulfate titrations. Typical results obtained are also provided for each type of titration. (JN)

Detoxification with titration and tapering in gamma-hydroxybutyrate (GHB) dependent patients: The Dutch GHB monitor project.

PubMed

Dijkstra, Boukje A G; Kamal, Rama; van Noorden, Martijn S; de Haan, Hein; Loonen, Anton J M; De Jong, Cor A J

2017-01-01

Gamma-hydroxybutyrate (GHB) detoxification procedures have been insufficiently studied for effectiveness and safety. Based on case reports, benzodiazepines are generally regarded as first-choice agents in GHB detoxification. Detoxification by titration and tapering (DeTiTap) with pharmaceutical GHB in an open-label consecutive case series of 23 GHB-dependent patients showed to be feasible, effective and safe. This study further explored the feasibility, effectiveness and safety of this detoxification procedure in a large group of patients. A large observational multicenter study was carried out in six addiction treatment centers in the Netherlands. GHB-dependent inpatients (229 unique patients, 274 admissions) were titrated on and tapered off with pharmaceutical GHB. Successful detoxification was achieved in 85% of cases. Detoxification was carried out in 12.5days in most patients. The DeTiTap procedure proved to be feasible and significantly reduced the experienced withdrawal symptoms and craving (p≤0.001). Several symptoms were found to influence the course of subjective withdrawal symptoms. During detoxification, psychological symptoms such as depression, anxiety, and stress decreased (p≤0.05). The main complications were hypertension and anxiety. Six patients were sent to the general hospital for observation, but all six were able to continue detoxification in the addiction treatment centers. Most patients (69%) relapsed within three months after detoxification. The DeTiTap procedure using pharmaceutical GHB seems a safe alternative to benzodiazepines as a GHB detoxification procedure. However, the high relapse rates warrant further investigation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Novel approaches to analysis by flow injection gradient titration.

PubMed

Wójtowicz, Marzena; Kozak, Joanna; Kościelniak, Paweł

2007-09-26

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

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

PubMed

Salonen, K; Leisola, M; Eerikäinen, T

2009-01-01

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

Evaluation on the use of cerium in the NBL Titrimetric Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zebrowski, J.P.; Orlowicz, G.J.; Johnson, K.D.

An alternative to potassium dichromate as titrant in the New Brunswick Laboratory Titrimetric Method for uranium analysis was sought since chromium in the waste makes disposal difficult. Substitution of a ceric-based titrant was statistically evaluated. Analysis of the data indicated statistically equivalent precisions for the two methods, but a significant overall bias of +0.035% for the ceric titrant procedure. The cause of the bias was investigated, alterations to the procedure were made, and a second statistical study was performed. This second study revealed no statistically significant bias, nor any analyst-to-analyst variation in the ceric titration procedure. A statistically significant day-to-daymore » variation was detected, but this was physically small (0.01 5%) and was only detected because of the within-day precision of the method. The added mean and standard deviation of the %RD for a single measurement was found to be 0.031%. A comparison with quality control blind dichromate titration data again indicated similar overall precision. Effects of ten elements on the ceric titration`s performance was determined. Co, Ti, Cu, Ni, Na, Mg, Gd, Zn, Cd, and Cr in previous work at NBL these impurities did not interfere with the potassium dichromate titrant. This study indicated similar results for the ceric titrant, with the exception of Ti. All the elements (excluding Ti and Cr), caused no statistically significant bias in uranium measurements at levels of 10 mg impurity per 20-40 mg uranium. The presence of Ti was found to cause a bias of {minus}0.05%; this is attributed to the presence of sulfate ions, resulting in precipitation of titanium sulfate and occlusion of uranium. A negative bias of 0.012% was also statistically observed in the samples containing chromium impurities.« less

Non-Aqueous Titration Method for Determining Suppressor Concentration in the MCU Next Generation Solvent (NGS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor-Pashow, Kathryn M. L.; Jones, Daniel H.

A non-aqueous titration method has been used for quantifying the suppressor concentration in the MCU solvent hold tank (SHT) monthly samples since the Next Generation Solvent (NGS) was implemented in 2013. The titration method measures the concentration of the NGS suppressor (TiDG) as well as the residual tri-n-octylamine (TOA) that is a carryover from the previous solvent. As the TOA concentration has decreased over time, it has become difficult to resolve the TiDG equivalence point as the TOA equivalence point has moved closer. In recent samples, the TiDG equivalence point could not be resolved, and therefore, the TiDG concentration wasmore » determined by subtracting the TOA concentration as measured by semi-volatile organic analysis (SVOA) from the total base concentration as measured by titration. In order to improve the titration method so that the TiDG concentration can be measured directly, without the need for the SVOA data, a new method has been developed that involves spiking of the sample with additional TOA to further separate the two equivalence points in the titration. This method has been demonstrated on four recent SHT samples and comparison to results obtained using the SVOA TOA subtraction method shows good agreement. Therefore, it is recommended that the titration procedure be revised to include the TOA spike addition, and this to become the primary method for quantifying the TiDG.« less

Assessment of two theoretical methods to estimate potentiometrictitration curves of peptides: comparison with experiment

PubMed Central

Makowska, Joanna; Bagiñska, Katarzyna; Makowski, Mariusz; Jagielska, Anna; Liwo, Adam; Kasprzykowski, Franciszek; Chmurzyñski, Lech; Scheraga, Harold A.

2008-01-01

We compared the ability of two theoretical methods of pH-dependent conformational calculations to reproduce experimental potentiometric-titration curves of two models of peptides: Ac-K5-NHMe in 95% methanol (MeOH)/5% water mixture and Ac-XX(A)7OO-NH2 (XAO) (where X is diaminobutyric acid, A is alanine, and O is ornithine) in water, methanol (MeOH) and dimethylsulfoxide (DMSO), respectively. The titration curve of the former was taken from the literature, and the curve of the latter was determined in this work. The first theoretical method involves a conformational search using the Electrostatically Driven Monte Carlo (EDMC) method with a low-cost energy function (ECEPP/3 plus the SRFOPT surface-solvation model, assumming that all titratable groups are uncharged) and subsequent reevaluation of the free energy at a given pH with the Poisson-Boltzmann equation, considering variable protonation states. In the second procedure, MD simulations are run with the AMBER force field and the Generalized-Born model of electrostatic solvation, and the protonation states are sampled during constant-pH MD runs. In all three solvents, the first pKa of XAO is strongly downshifted compared to the value for the reference compounds (ethyl amine and propyl amine, respectively); the water and methanol curves have one, and the DMSO curve has two jumps characteristic of remarkable differences in the dissociation constants of acidic groups. The predicted titration curves of Ac-K5-NHMe are in good agreement with the experimental ones; better agreement is achieved with the MD-based method. The titration curves of XAO in methanol and DMSO, calculated using the MD-based approach, trace the shape of the experimental curves, reproducing the pH jump, while those calculated with the EDMC-based approach, and the titration curve in water calculated using the MD-based approach, have smooth shapes characteristic of the titration of weak multifunctional acids with small differences between the dissociation constants. Nevertheless, quantitative agreement between theoretically predicted and experimental titration curves is not achieved in all three solvents even with the MD-based approach which is manifested by a smaller pH range of the calculated titration curves with respect to the experimental curves. The poorer agreement obtained for water than for the non-aqueous solvents suggests a significant role of specific solvation in water, which cannot be accounted for by the mean-field solvation models. PMID:16509748

Determination of sulphite in wine by coulometric titration.

PubMed

Lowinsohn, D; Bertotti, M

2001-09-01

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

ASSESSMENT OF ATTENTION THRESHOLD IN RATS BY TITRATION OF VISUAL CUE DURATION DURING THE FIVE CHOICE SERIAL REACTION TIME TASK

PubMed Central

Martin, Thomas J.; Grigg, Amanda; Kim, Susy A.; Ririe, Douglas G.; Eisenach, James C.

2014-01-01

Background The 5 choice serial reaction time task (5CSRTT) is commonly used to assess attention in rodents. We sought to develop a variant of the 5CSRTT that would speed training to objective success criteria, and to test whether this variant could determine attention capability in each subject. New Method Fisher 344 rats were trained to perform a variant of the 5CSRTT in which the duration of visual cue presentation (cue duration) was titrated between trials based upon performance. The cue duration was decreased when the subject made a correct response, or increased with incorrect responses or omissions. Additionally, test day challenges were provided consisting of lengthening the intertrial interval and inclusion of a visual distracting stimulus. Results Rats readily titrated the cue duration to less than 1 sec in 25 training sessions or less (mean ± SEM, 22.9 ± 0.7), and the median cue duration (MCD) was calculated as a measure of attention threshold. Increasing the intertrial interval increased premature responses, decreased the number of trials completed, and increased the MCD. Decreasing the intertrial interval and time allotted for consuming the food reward demonstrated that a minimum of 3.5 sec is required for rats to consume two food pellets and successfully attend to the next trial. Visual distraction in the form of a 3 Hz flashing light increased the MCD and both premature and time out responses. Comparison with existing method The titration variant of the 5CSRTT is a useful method that dynamically measures attention threshold across a wide range of subject performance, and significantly decreases the time required for training. Task challenges produce similar effects in the titration method as reported for the classical procedure. Conclusions The titration 5CSRTT method is an efficient training procedure for assessing attention and can be utilized to assess the limit in performance ability across subjects and various schedule manipulations. PMID:25528113

End-point detection in potentiometric titration by continuous wavelet transform.

PubMed

Jakubowska, Małgorzata; Baś, Bogusław; Kubiak, Władysław W

2009-10-15

The aim of this work was construction of the new wavelet function and verification that a continuous wavelet transform with a specially defined dedicated mother wavelet is a useful tool for precise detection of end-point in a potentiometric titration. The proposed algorithm does not require any initial information about the nature or the type of analyte and/or the shape of the titration curve. The signal imperfection, as well as random noise or spikes has no influence on the operation of the procedure. The optimization of the new algorithm was done using simulated curves and next experimental data were considered. In the case of well-shaped and noise-free titration data, the proposed method gives the same accuracy and precision as commonly used algorithms. But, in the case of noisy or badly shaped curves, the presented approach works good (relative error mainly below 2% and coefficients of variability below 5%) while traditional procedures fail. Therefore, the proposed algorithm may be useful in interpretation of the experimental data and also in automation of the typical titration analysis, specially in the case when random noise interfere with analytical signal.

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

PubMed

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

2008-12-01

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.

Initiation of Levodopa-Carbidopa Intestinal Gel Infusion Using Telemedicine (Video Communication System) Facilitates Efficient and Well-Accepted Home Titration in Patients with Advanced Parkinson’s Disease

PubMed Central

Willows, Thomas; Dizdar, Nil; Nyholm, Dag; Widner, Håkan; Grenholm, Peter; Schmiauke, Ursula; Urbom, Anna; Groth, Kristina; Larsson, Jörgen; Permert, Johan; Kjellander, Susanna

2017-01-01

Background: Levodopa-carbidopa intestinal gel (LCIG; Duodopa®) is used for continuous infusion in advanced Parkinson’s disease. To achieve optimal effect, the LCIG dose is individually titrated, traditionally conducted during hospitalization in Sweden. However, dose adjustment depends on surrounding conditions, physical activity, and emotional stress, which is why titration at home could be beneficial. Telemedicine (TM) using a video communication system offers alternative titration procedures, allowing LCIG initiation at home. Objective: Study objectives were to show the feasibility of TM for LCIG home titration, evaluate resource use, and assess patient, neurologist, and nurse satisfaction. Methods: Four clinics enrolled 15 patients to observe efficiency and feasibility of TM-based monitoring. Results: Patient median (range) age was 67 (52–73) years and time since diagnosis was 10 (7–23) years. Median time between LCIG initiation and end of TM-assisted titration was 2.8 (2.0–13.8) days. Median time required for home titration by neurologists, nurses, and patients was (hours:minutes) 1 : 14 (0 : 29–1 : 52), 5 : 49 (2 : 46–10 : 3), and 8 : 53 (4 : 11–14 : 11), respectively. Neurologists and nurses considered this to be less time than required for hospital titration. TM allowed patients 92% free time from start to end of titration. Technical problems associated with TM contacts were rare, mostly related to digital link, and quickly resolved. Patients, neurologists, and nurses were satisfied using TM. No serious adverse events were reported; there was one device complaint (tube occlusion). Conclusions: In this study, TM-assisted LCIG titration at home was resource-efficient, technically feasible, well-accepted and was deemed satisfactory by patients, neurologists, and nurses. PMID:28984615

Determination of Ammonia in Household Cleaners: An Instrumental Analysis Experiment.

ERIC Educational Resources Information Center

Graham, Richard C.; DePew, Steven

1983-01-01

Briefly discusses three techniques for assessing amount of ammonia present in household cleaners. Because of disadvantages with these methods, the thermometric titration technique is suggested in which students judge the best buy based on relative cost of ammonia present in samples. Laboratory procedures, typical results, and reactions involved…

Four points function fitted and first derivative procedure for determining the end points in potentiometric titration curves: statistical analysis and method comparison.

PubMed

Kholeif, S A

2001-06-01

A new method that belongs to the differential category for determining the end points from potentiometric titration curves is presented. It uses a preprocess to find first derivative values by fitting four data points in and around the region of inflection to a non-linear function, and then locate the end point, usually as a maximum or minimum, using an inverse parabolic interpolation procedure that has an analytical solution. The behavior and accuracy of the sigmoid and cumulative non-linear functions used are investigated against three factors. A statistical evaluation of the new method using linear least-squares method validation and multifactor data analysis are covered. The new method is generally applied to symmetrical and unsymmetrical potentiometric titration curves, and the end point is calculated using numerical procedures only. It outperforms the "parent" regular differential method in almost all factors levels and gives accurate results comparable to the true or estimated true end points. Calculated end points from selected experimental titration curves compatible with the equivalence point category of methods, such as Gran or Fortuin, are also compared with the new method.

Titrating Oxygen Requirements During Exercise: Evaluation of a Standardized Single Walk Test Protocol.

PubMed

Giovacchini, Coral X; Mathews, Anne M; Lawlor, Brian R; MacIntyre, Neil R

2018-04-01

Oxygen supplementation for exercise-induced hypoxemia is a common clinical practice that improves exercise tolerance. However, we know of no standardized exercise oxygen titration protocol using a single walk test. We report our experience with a protocol developed in our laboratory. Our protocol is based on the 6-min walk test (6MWT). Pulse oximetry readings (oxygen saturation [Spo 2 ]) are monitored, and supplemental oxygen is added in 2 L/min increments to keep Spo 2 > 88%. This continues for at least 6 min of walking with the Spo 2 remaining > 88% for at least 3 min. The records of consecutive patients over 4 months undergoing this procedure were reviewed for test performance, oxygen titration results, and adverse events. Two hundred twenty-two patients were tested; only two prematurely terminated the protocol because of intractable dyspnea. One hundred fifty-six patients (38%) required oxygen supplementation, with the first titration most commonly occurring between 1 and 2 min of walking. Nine of the patients had the first titration after 5 min of walking. The average test duration was 7 min (maximum, 15 min). The average number of titrations was 2.2 (maximum six). Sixteen patients could not maintain Spo 2 > 88% for 3 min despite administration of 15 L/min of supplemental oxygen (maximal dose). Our protocol was easily performed as a modification of a standard 6MWT with no serious adverse events. Because it is based on a widely accepted measurement of functional capabilities, and because it determined a stable final oxygen dose for ≥ 3 min of walking in most patients, we believe this protocol can be easily adapted for clinical use. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

3-D Topo Surface Visualization of Acid-Base Species Distributions: Corner Buttes, Corner Pits, Curving Ridge Crests, and Dilution Plains

ERIC Educational Resources Information Center

Smith, Garon C.; Hossain, Md Mainul

2017-01-01

Species TOPOS is a free software package for generating three-dimensional (3-D) topographic surfaces ("topos") for acid-base equilibrium studies. This upgrade adds 3-D species distribution topos to earlier surfaces that showed pH and buffer capacity behavior during titration and dilution procedures. It constructs topos by plotting…

Development and validation of a simplified titration method for monitoring volatile fatty acids in anaerobic digestion.

PubMed

Sun, Hao; Guo, Jianbin; Wu, Shubiao; Liu, Fang; Dong, Renjie

2017-09-01

The volatile fatty acids (VFAs) concentration has been considered as one of the most sensitive process performance indicators in anaerobic digestion (AD) process. However, the accurate determination of VFAs concentration in AD processes normally requires advanced equipment and complex pretreatment procedures. A simplified method with fewer sample pretreatment procedures and improved accuracy is greatly needed, particularly for on-site application. This report outlines improvements to the Nordmann method, one of the most popular titrations used for VFA monitoring. The influence of ion and solid interfering subsystems in titrated samples on results accuracy was discussed. The total solid content in titrated samples was the main factor affecting accuracy in VFA monitoring. Moreover, a high linear correlation was established between the total solids contents and VFA measurement differences between the traditional Nordmann equation and gas chromatography (GC). Accordingly, a simplified titration method was developed and validated using a semi-continuous experiment of chicken manure anaerobic digestion with various organic loading rates. The good fitting of the results obtained by this method in comparison with GC results strongly supported the potential application of this method to VFA monitoring. Copyright © 2017. Published by Elsevier Ltd.

Acid Rain Analysis by Standard Addition Titration.

ERIC Educational Resources Information Center

Ophardt, Charles E.

1985-01-01

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

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

ERIC Educational Resources Information Center

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

2011-01-01

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

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

PubMed

Scherrer, Robert A; Donovan, Stephen F

2009-04-01

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

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

PubMed Central

2009-01-01

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

Titrimetric Analysis of Han-Based Liquid Propellants

DTIC Science & Technology

1988-03-01

acid-base and Karl Fischer titrimetry, procedures that quantitatively determine the three major propellant components. The method developed converts...sodium hydroxide as titrant for both HAN and TEAN. Water is determined by Karl Fischer titration using the proprietary reagent "Hydranal". Each major...water, react with one or more of the components of the Karl Fischer reagent. One of the newer Karl Fischer titrants is "Hydranal", a proprietary reagent

Novel microscale approaches for easy, rapid determination of protein stability in academic and commercial settings

PubMed Central

Alexander, Crispin G.; Wanner, Randy; Johnson, Christopher M.; Breitsprecher, Dennis; Winter, Gerhard; Duhr, Stefan; Baaske, Philipp; Ferguson, Neil

2014-01-01

Chemical denaturant titrations can be used to accurately determine protein stability. However, data acquisition is typically labour intensive, has low throughput and is difficult to automate. These factors, combined with high protein consumption, have limited the adoption of chemical denaturant titrations in commercial settings. Thermal denaturation assays can be automated, sometimes with very high throughput. However, thermal denaturation assays are incompatible with proteins that aggregate at high temperatures and large extrapolation of stability parameters to physiological temperatures can introduce significant uncertainties. We used capillary-based instruments to measure chemical denaturant titrations by intrinsic fluorescence and microscale thermophoresis. This allowed higher throughput, consumed several hundred-fold less protein than conventional, cuvette-based methods yet maintained the high quality of the conventional approaches. We also established efficient strategies for automated, direct determination of protein stability at a range of temperatures via chemical denaturation, which has utility for characterising stability for proteins that are difficult to purify in high yield. This approach may also have merit for proteins that irreversibly denature or aggregate in classical thermal denaturation assays. We also developed procedures for affinity ranking of protein–ligand interactions from ligand-induced changes in chemical denaturation data, and proved the principle for this by correctly ranking the affinity of previously unreported peptide–PDZ domain interactions. The increased throughput, automation and low protein consumption of protein stability determinations afforded by using capillary-based methods to measure denaturant titrations, can help to revolutionise protein research. We believe that the strategies reported are likely to find wide applications in academia, biotherapeutic formulation and drug discovery programmes. PMID:25262836

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

ERIC Educational Resources Information Center

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

2012-01-01

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

Tested Demonstrations: Buffer Capacity of Various Acetic Acid-Sodium Acetate Systems: A Lecture Experiment.

ERIC Educational Resources Information Center

Donahue, Craig J.; Panek, Mary G.

1985-01-01

Background information and procedures are provided for a lecture experiment which uses indicators to illustrate the concept of differing buffer capacities by titrating acetic acid/sodium acetate buffers with 1.0 molar hydrochloric acid and 1.0 molar sodium hydroxide. A table with data used to plot the titration curve is included. (JN)

Droplet-counting Microtitration System for Precise On-site Analysis.

PubMed

Kawakubo, Susumu; Omori, Taichi; Suzuki, Yasutada; Ueta, Ikuo

2018-01-01

A new microtitration system based on the counting of titrant droplets has been developed for precise on-site analysis. The dropping rate was controlled by inserting a capillary tube as a flow resistance in a laboratory-made micropipette. The error of titration was 3% in a simulated titration with 20 droplets. The pre-addition of a titrant was proposed for precise titration within an error of 0.5%. The analytical performances were evaluated for chelate titration, redox titration and acid-base titration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor-Pashow, K.; Fondeur, F.; White, T.

Savannah River National Laboratory (SRNL) was tasked with identifying and developing at least one, but preferably two methods for quantifying the suppressor in the Next Generation Solvent (NGS) system. The suppressor is a guanidine derivative, N,N',N"-tris(3,7-dimethyloctyl)guanidine (TiDG). A list of 10 possible methods was generated, and screening experiments were performed for 8 of the 10 methods. After completion of the screening experiments, the non-aqueous acid-base titration was determined to be the most promising, and was selected for further development as the primary method. {sup 1}H NMR also showed promising results from the screening experiments, and this method was selected formore » further development as the secondary method. Other methods, including {sup 36}Cl radiocounting and ion chromatography, also showed promise; however, due to the similarity to the primary method (titration) and the inability to differentiate between TiDG and TOA (tri-n-ocytlamine) in the blended solvent, {sup 1}H NMR was selected over these methods. Analysis of radioactive samples obtained from real waste ESS (extraction, scrub, strip) testing using the titration method showed good results. Based on these results, the titration method was selected as the method of choice for TiDG measurement. {sup 1}H NMR has been selected as the secondary (back-up) method, and additional work is planned to further develop this method and to verify the method using radioactive samples. Procedures for analyzing radioactive samples of both pure NGS and blended solvent were developed and issued for the both methods.« less

Theoretical problems associated with the use of acetic anhydride as a co-solvent for the non-aqueous titration of hydrohalides of organic bases and quaternary ammonium salts.

PubMed

Völgyi, Gergely; Béni, Szabolcs; Takács-Novák, Krisztina; Görög, Sándor

2010-01-05

A potentiometric titration study of organic base hydrohalides and quaternary ammonium salts using perchloric acid as the titrant and a mixture of acetic anhydride and acetic acid as the solvent was carried out and the titration mixture was analysed by NMR in order to clarify the chemistry of the reactions involved. It was found that in contrast to the general belief the formation of acetyl halides and titratable free acetate ion does not take place prior to the titration but NMR spectra proved the formation of acetyl halides in the course of the titration. This observation and the fact that the shape of the titration curves depends on the nature of the hydrohaloic acid bound to the base or of the anion in the quaternary ammonium salts led to the conclusion that the titrating agent is acetyl perchlorate formed in situ during the titration. Equations of the reactions involved in the titration process are shown in the paper.

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

PubMed

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

2014-12-16

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

Students' integration of multiple representations in a titration experiment

NASA Astrophysics Data System (ADS)

Kunze, Nicole M.

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

Aquaporin-4 antibody titration in NMO patients treated with rituximab: A retrospective study.

PubMed

Valentino, Paola; Marnetto, Fabiana; Granieri, Letizia; Capobianco, Marco; Bertolotto, Antonio

2017-03-01

We undertook an observational retrospective study to investigate the usefulness of aquaporin-4 (AQP4) antibodies (Ab) titration in the management of patients with neuromyelitis optica (NMO) treated with rituximab (RTX) by studying (1) the correlation between AQP4-Ab titer and disease activity, (2) the influence of RTX on antibody levels, and (3) the association between AQP4-Ab levels and responsiveness to RTX. A cell-based assay was used for AQP4-Ab titration in 322 serum samples from 7 patients with NMO treated with RTX (median follow-up 65 months), according to a treatment-to-target approach. Serum samples were collected every month following standardized procedures. (1) In group analysis, AQP4-Ab titers correlated with the disease activity, showing higher titers during and preceding relapses than during remission. However, in individual analysis, an increase in AQP4-Ab titers and CD19+ B cells did not always precede a relapse. (2) A reduction of AQP4-Ab titers in the short-term and long-term period was observed during RTX treatment. (3) Reduction of AQP4-Ab titers was observed in responder patients both 3 months after RTX infusion and in the long-term follow-up. In one nonresponder patient, AQP4-Ab levels never decreased during the treatment period. Titration of AQP4-Abs could be useful in the clinical management of patients with NMO treated with RTX: titration before each reinfusion and 3 months after each reinfusion may provide information about responsiveness to RTX. Although a relationship among AQP4-Ab levels, disease activity, and response to RTX was observed, the usefulness of AQP4-Ab titration to predict relapses is limited.

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2011 CFR

2011-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment... procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas Engineers Handbook, Fuel.... In principle, this method consists of titrating hydrogen sulfide in a gas sample directly with a...

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2010 CFR

2010-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment... procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas Engineers Handbook, Fuel.... In principle, this method consists of titrating hydrogen sulfide in a gas sample directly with a...

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2013 CFR

2013-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment..., 2011 § 60.648 Optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas... dilute solutions are used. In principle, this method consists of titrating hydrogen sulfide in a gas...

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2012 CFR

2012-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment... procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas Engineers Handbook, Fuel.... In principle, this method consists of titrating hydrogen sulfide in a gas sample directly with a...

40 CFR 60.5408 - What is an optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure?

Code of Federal Regulations, 2013 CFR

2013-07-01

... measuring hydrogen sulfide in acid gas-Tutwiler Procedure? 60.5408 Section 60.5408 Protection of Environment... § 60.5408 What is an optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure... of titrating hydrogen sulfide in a gas sample directly with a standard solution of iodine. (b...

40 CFR 60.5408 - What is an optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure?

Code of Federal Regulations, 2014 CFR

2014-07-01

... measuring hydrogen sulfide in acid gas-Tutwiler Procedure? 60.5408 Section 60.5408 Protection of Environment... § 60.5408 What is an optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure... of titrating hydrogen sulfide in a gas sample directly with a standard solution of iodine. (b...

40 CFR 60.648 - Optional procedure for measuring hydrogen sulfide in acid gas-Tutwiler Procedure. 1

Code of Federal Regulations, 2014 CFR

2014-07-01

... hydrogen sulfide in acid gas-Tutwiler Procedure. 1 60.648 Section 60.648 Protection of Environment..., 2011 § 60.648 Optional procedure for measuring hydrogen sulfide in acid gas—Tutwiler Procedure. 1 1 Gas... dilute solutions are used. In principle, this method consists of titrating hydrogen sulfide in a gas...

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

PubMed

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

2007-10-01

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

Visualization of Buffer Capacity with 3-D "Topo" Surfaces: Buffer Ridges, Equivalence Point Canyons and Dilution Ramps

ERIC Educational Resources Information Center

Smith, Garon C.; Hossain, Md Mainul

2016-01-01

BufCap TOPOS is free software that generates 3-D topographical surfaces ("topos") for acid-base equilibrium studies. It portrays pH and buffer capacity behavior during titration and dilution procedures. Topo surfaces are created by plotting computed pH and buffer capacity values above a composition grid with volume of NaOH as the x axis…

Standard Free Droplet Digital Polymerase Chain Reaction as a New Tool for the Quality Control of High-Capacity Adenoviral Vectors in Small-Scale Preparations

PubMed Central

Boehme, Philip; Stellberger, Thorsten; Solanki, Manish; Zhang, Wenli; Schulz, Eric; Bergmann, Thorsten; Liu, Jing; Doerner, Johannes; Baiker, Armin E.

2015-01-01

Abstract High-capacity adenoviral vectors (HCAdVs) are promising tools for gene therapy as well as for genetic engineering. However, one limitation of the HCAdV vector system is the complex, time-consuming, and labor-intensive production process and the following quality control procedure. Since HCAdVs are deleted for all viral coding sequences, a helper virus (HV) is needed in the production process to provide the sequences for all viral proteins in trans. For the purification procedure of HCAdV, cesium chloride density gradient centrifugation is usually performed followed by buffer exchange using dialysis or comparable methods. However, performing these steps is technically difficult, potentially error-prone, and not scalable. Here, we establish a new protocol for small-scale production of HCAdV based on commercially available adenovirus purification systems and a standard method for the quality control of final HCAdV preparations. For titration of final vector preparations, we established a droplet digital polymerase chain reaction (ddPCR) that uses a standard free-end-point PCR in small droplets of defined volume. By using different probes, this method is capable of detecting and quantifying HCAdV and HV in one reaction independent of reference material, rendering this method attractive for accurately comparing viral titers between different laboratories. In summary, we demonstrate that it is possible to produce HCAdV in a small scale of sufficient quality and quantity to perform experiments in cell culture, and we established a reliable protocol for vector titration based on ddPCR. Our method significantly reduces time and required equipment to perform HCAdV production. In the future the ddPCR technology could be advantageous for titration of other viral vectors commonly used in gene therapy. PMID:25640117

Switching From Age-Based Stimulus Dosing to Dose Titration Protocols in Electroconvulsive Therapy: Empirical Evidence for Better Patient Outcomes With Lower Peak and Cumulative Energy Doses.

PubMed

O'Neill-Kerr, Alex; Yassin, Anhar; Rogers, Stephen; Cornish, Janie

2017-09-01

The aim of this study was to test the proposition that adoption of a dose titration protocol may be associated with better patient outcomes, at lower treatment dose, and with comparable cumulative dose to that in patients treated using an age-based stimulus dosing protocol. This was an analysis of data assembled from archived records and based on cohorts of patients treated respectively on an age-based stimulus dosing protocol and on a dose titration protocol in the National Health Service in England. We demonstrated a significantly better response in the patient cohort treated with dose titration than with age-based stimulus dosing. Peak doses were less and the total cumulative dose was less in the dose titration group than in the age-based stimulus dosing group. Our findings are consistent with superior outcomes in patients treated using a dose titration protocol when compared with age-based stimulus dosing in a similar cohort of patients.

A Closer Look at Acid-Base Olfactory Titrations

ERIC Educational Resources Information Center

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

2005-01-01

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

Comparative study of procedures for the analysis of chloride in hardened concrete.

DOT National Transportation Integrated Search

1976-01-01

In the widely used potentiometric titration procedure for the analysis of chloride in powdered hardened concrete samples, difficulties have often been encountered when determining the endpoint. These difficulties have been eliminated through the use ...

An Olfactory Indicator for Acid-Base Titrations.

ERIC Educational Resources Information Center

Flair, Mark N.; Setzer, William N.

1990-01-01

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

Determining a Solubility Product Constant by Potentiometric Titration to Increase Students' Conceptual Understanding of Potentiometry and Titrations

ERIC Educational Resources Information Center

Grabowski, Lauren E.; Goode, Scott R.

2017-01-01

Potentiometric titrations are widely taught in first-year undergraduate courses to connect electrochemistry, stoichiometry, and equilibria and to reinforce acid-base titrations. Students perform a potentiometric titration that is then analyzed to determine analyte concentrations and the solubility product constant of the solid species.

Determination of organic bases in non-aqueous solvents by catalytic thermometric titration.

PubMed

Vajgand, V J; Kiss, T A; Gaál, F F; Zsigrai, I J

1968-07-01

Catalytic thermometric titrations have been developed for bases (brucine, diethylaniline, potassium acetate and triethylamine) in acetic acid by continuous and discontinuous addition of the standard solution and automatic temperature recording. The determination of weak bases, e.g., antipyrine, unsuccessful in acetic acid by catalytic thermometric titration, has been achieved by using nitromethane or acetic anhydride as solvent. Catalytic thermometric titrations were also performed by coulometric generation of hydrogen ions for the determination of micro amounts of weak bases in a mixture of acetic anhyride and acetic acid.

Analysis of Aircraft Fuels and Related Materials

DTIC Science & Technology

1982-09-01

content by the Karl Fischer method . Each 2040 solvent sample represented a different step in a clean-up procedure conducted by Aero Propulsion...izes a potentiometric titration with alcoholic silver nitrate. This method has a minimum detectability of 1 ppm. It has a re- peatability of 0.1 ppm... Method 163-80, which util- izes a potentiometric titration with alcoholic silver nitrate. This method has a minimum detectability of 1 ppm and has a

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

PubMed

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

2011-11-01

We propose a high precision rapid personal computer (PC) based potentiometric titration technique using a specially designed mini-cell to carry out redox titrations for assay of chemicals in quality control laboratories attached to industrial, R&D, and nuclear establishments. Using this technique a few microlitre of sample (50-100 μl) in a total volume of ~2 ml solution can be titrated and the waste generated after titration is extremely low comparing to that obtained from the conventional titration technique. The entire titration including online data acquisition followed by immediate offline analysis of data to get information about concentration of unknown sample is completed within a couple of minutes (about 2 min). This facility has been created using a new class of sensors, viz., pulsating sensors developed in-house. The basic concept in designing such instrument and the salient features of the titration device are presented in this paper. The performance of the titration facility was examined by conducting some of the high resolution redox titrations using dilute solutions--hydrazine against KIO(3) in HCl medium, Fe(II) against Ce(IV) and uranium using Davies-Gray method. The precision of titrations using this innovative approach lies between 0.048% and 1.0% relative standard deviation in different redox titrations. With the evolution of this rapid PC based titrator it was possible to develop a simple but high precision potentiometric titration technique for quick determination of hydrazine in nuclear fuel dissolver solution in the context of reprocessing of spent nuclear fuel in fast breeder reactors. © 2011 American Institute of Physics

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

NASA Astrophysics Data System (ADS)

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

2011-11-01

We propose a high precision rapid personal computer (PC) based potentiometric titration technique using a specially designed mini-cell to carry out redox titrations for assay of chemicals in quality control laboratories attached to industrial, R&D, and nuclear establishments. Using this technique a few microlitre of sample (50-100 μl) in a total volume of ˜2 ml solution can be titrated and the waste generated after titration is extremely low comparing to that obtained from the conventional titration technique. The entire titration including online data acquisition followed by immediate offline analysis of data to get information about concentration of unknown sample is completed within a couple of minutes (about 2 min). This facility has been created using a new class of sensors, viz., pulsating sensors developed in-house. The basic concept in designing such instrument and the salient features of the titration device are presented in this paper. The performance of the titration facility was examined by conducting some of the high resolution redox titrations using dilute solutions--hydrazine against 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.

Potentiometric/turbidometric titration of antiperspirant actives.

PubMed

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

2003-01-01

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

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

PubMed

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

2006-11-01

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.

Process for Assessing the Stability of HAN (Hydroxylamine)-Based Liquid Propellants.

DTIC Science & Technology

1987-07-29

liquid propellants on the basis of HAN according to Fig. 1 can be determined directly by Fischer titration. This method requires a special unit, as the...Wasserreagenzien nach Eugen Scholz fUr die Karl - Fischer -Titration (Guidelines by Messrs. Riedel-de Haen for Titration according to the Karl Fischer ...Propellant components 2 2.2 Methods of determination 3 2.3 Acid/base titration and pK values 4 2.4 The Titroprozessor 636 8 2.5 Propellant analyses 10

Time-to-isolation guided titration of freeze duration in 3rd generation short-tip cryoballoon pulmonary vein isolation - Comparable clinical outcome and shorter procedure duration.

PubMed

Pott, Alexander; Kraft, Christoph; Stephan, Tilman; Petscher, Kerstin; Rottbauer, Wolfgang; Dahme, Tillman

2018-03-15

The optimal freeze duration in cryoballoon pulmonary vein isolation (PVI) is unknown. The 3rd generation cryoballoon facilitates observation of the time-to-isolation (TTI) and thereby enables individualized cryoenergy titration. To evaluate the efficacy of an individualized freeze duration we compared the clinical outcome of patients treated with a TTI-guided ablation protocol to the outcome of patients treated with a fixed ablation protocol. We compared 100 patients treated with the 3rd generation cryoballoon applying a TTI-based protocol (TTI group) to 100 patients treated by a fixed freeze protocol (fixed group). In the fixed group a 240s freeze cycle was followed by a 240s bonus freeze after acute PV isolation. In the TTI group freeze duration was 180s if TTI was ≥30s and reduced to only 120s, if TTI was <30s. In case of a TTI >60s a 180s bonus freeze was applied. Freedom from atrial arrhythmia recurrence off class I/III antiarrhythmic drugs after one year was not different between the TTI group (73.6%) and the fixed group (75.7%; p=0.75). Mean procedure duration was 85.8±27.3min in the TTI group compared to 115.7±27.1min in the fixed group (p<0.001). Mean fluoroscopy time was 17.5±6.6min in the TTI group and 22.5±9.8min in the fixed group (p<0.001). TTI-guided cryoenergy titration leads to reduced procedure duration and fluoroscopy time and appears to be as effective as a fixed ablation strategy. A single 2-minute freeze seems to be sufficient in case of short TTI. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Titration Curves: Fact and Fiction.

ERIC Educational Resources Information Center

Chamberlain, John

1997-01-01

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

Chem Ed Compacts

ERIC Educational Resources Information Center

Wolf, Walter A., Ed.

1978-01-01

Presents four simple laboratory procedures for: preparation of organometallic compounds, a realistic qualitative organic analysis project, a computer program to plot potentiometric titration curves, and preparation of stereoscopic transparencies. (SL)

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

NASA Technical Reports Server (NTRS)

Meites, L.

1978-01-01

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.

Linear Titration Curves of Acids and Bases.

PubMed

Joseph, N R

1959-05-29

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.

Thermometric titration of cadmium with sodium diethyldithiocarbamate, with oxidation by hydrogen peroxide as indicator reaction.

PubMed

Hattori, T; Yoshida, H

1987-08-01

A new method of end-point indication is described for thermometric titration of cadmium with sodium diethyldithiocarbamate (DDTC). It is based on the redox reaction between hydrogen peroxide added to the system before titration, and the first excess of DDTC. Amounts of cadmium in the range 10-50 mumoles are titrated within 1% error.

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

PubMed

Coelho, Lúcia H G; Gutz, Ivano G R

2006-03-15

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.

Determination of Carbonyl Groups in Pyrolysis Bio-oils Using Potentiometric Titration: Review and Comparison of Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Black, Stuart; Ferrell, Jack R.

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here in this study, we present a modification of the traditional carbonyl oximation procedures that results inmore » less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. Some compounds such as carbohydrates are not measured by the traditional method (modified Nicolaides method), resulting in low estimations of the carbonyl content. Furthermore, we have shown that reaction completion for the traditional method can take up to 300 hours. The new method presented here (the modified Faix method) reduces the reaction time to 2 hours, uses triethanolamine (TEA) in the place of pyridine, and requires a smaller sample size for the analysis. Carbonyl contents determined using this new method are consistently higher than when using the traditional titration methods.« less

Determination of Carbonyl Groups in Pyrolysis Bio-oils Using Potentiometric Titration: Review and Comparison of Methods

DOE PAGES

Black, Stuart; Ferrell, Jack R.

2016-01-06

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here in this study, we present a modification of the traditional carbonyl oximation procedures that results inmore » less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. Some compounds such as carbohydrates are not measured by the traditional method (modified Nicolaides method), resulting in low estimations of the carbonyl content. Furthermore, we have shown that reaction completion for the traditional method can take up to 300 hours. The new method presented here (the modified Faix method) reduces the reaction time to 2 hours, uses triethanolamine (TEA) in the place of pyridine, and requires a smaller sample size for the analysis. Carbonyl contents determined using this new method are consistently higher than when using the traditional titration methods.« less

Computer controlled titration with piston burette or peristaltic pump - a comparison.

PubMed

Hoffmann, W

1996-09-01

The advantages and problems of the use of piston burettes and peristaltic pumps for dosage of titrant solutions in automatic titrations are shown. For comparison, only the dosing devices were exchanged and all other components and conditions remained unchanged. The results of continuous acid base titration show good agreement and comparable reproducibility. Potentiometric sensors (glass electrodes) with different equilibration behaviour influence the results. The capability of such electrodes was tested. Conductometric measurements allow a much faster detection because there is no equilibration of electrodes. Piston burettes should be used for titration with very high precision, titration with organic solvents and slow titrations. Peristaltic pumps seem to be more suitable for continuous titrations and long time operation without service.

Titration Techniques

NASA Astrophysics Data System (ADS)

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

1995-07-01

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.

A Computer-Based Simulation of an Acid-Base Titration

ERIC Educational Resources Information Center

Boblick, John M.

1971-01-01

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)

Optimal level of continuous positive airway pressure: auto-adjusting titration versus titration with a predictive equation.

PubMed

Choi, Ji Ho; Jun, Young Joon; Oh, Jeong In; Jung, Jong Yoon; Hwang, Gyu Ho; Kwon, Soon Young; Lee, Heung Man; Kim, Tae Hoon; Lee, Sang Hag; Lee, Seung Hoon

2013-05-01

The aims of the present study were twofold. We sought to compare two methods of titrating the level of continuous positive airway pressure (CPAP) - auto-adjusting titration and titration using a predictive equation - with full-night manual titration used as the benchmark. We also investigated the reliability of the two methods in patients with obstructive sleep apnea syndrome (OSAS). Twenty consecutive adult patients with OSAS who had successful, full-night manual and auto-adjusting CPAP titration participated in this study. The titration pressure level was calculated with a previously developed predictive equation based on body mass index and apnea-hypopnea index. The mean titration pressure levels obtained with the manual, auto-adjusting, and predictive equation methods were 9.0 +/- 3.6, 9.4 +/- 3.0, and 8.1 +/- 1.6 cm H2O,respectively. There was a significant difference in the concordance within the range of +/- 2 cm H2O (p = 0.019) between both the auto-adjusting titration and the titration using the predictive equation compared to the full-night manual titration. However, there was no significant difference in the concordance within the range of +/- 1 cm H2O (p > 0.999). When compared to full-night manual titration as the standard method, auto-adjusting titration appears to be more reliable than using a predictive equation for determining the optimal CPAP level in patients with OSAS.

"Why not stoichiometry" versus "Stoichiometry--why not?" Part II: GATES in context with redox systems.

PubMed

Michałowska-Kaczmarczyk, Anna Maria; Asuero, Agustin G; Toporek, Marcin; Michałowski, Tadeusz

2015-01-01

Redox equilibria and titration play an important role in chemical analysis, and the formulation of an accurate mathematical description is a challenge. This article is devoted to static and (mainly) dynamic redox systems; the dynamic systems are represented by redox titrations. An overview addresses earlier approaches to static redox systems (redox diagram plots, including Pourbaix diagrams) and to titration redox systems, thereby covering a gap in the literature. After this short review, the generalized approach to electrolytic systems (GATES) is introduced, with generalized electron balance (GEB) as its inherent part within GATES/GEB. Computer simulation, performed according to GATES/GEB, enables following the changes in potential and pH of the solution, together with chemical speciation at each step of a titration, thus providing better insight into this procedure. The undeniable advantages of GATES/GEB over earlier approaches are indicated. Formulation of GEB according to two approaches (I and II) is presented on the respective examples. A general criterion distinguishing between non-redox and redox systems is presented. It is indicated that the formulation of GEB according to Approach II does not need the knowledge of oxidation degrees of particular elements; knowledge of the composition, expressed by chemical formula of the species and its charge, is sufficient for this purpose. Approach I to GEB, known also as the "short" version of GEB, is applicable if oxidation degrees for all elements of the system are known beforehand. The roles of oxidants and reductants are not ascribed to particular components forming a system and to the species thus formed. This is the complete opposite of earlier approaches to redox titrations, based on the stoichiometric redox reaction, formulated for this purpose. GEB, perceived as a law of matter conservation, is fully compatible with other (charge and concentration) balances related to the system in question. The applicability of GATES/GEB in optimization a priori of chemical analyses made with use of redox titration is indicated. The article is illustrated with many examples of static and dynamic redox systems. The related plots are obtained from calculations made according to iterative computer programs. This way, GATES/GEB enables seeing details invisible in real experiments.

Wet Labs, Computers, and Spreadsheets.

ERIC Educational Resources Information Center

Durham, Bill

1990-01-01

Described are some commonly encountered chemistry experiments that have been modified for computerized data acquisition. Included are exercises in radioactivity, titration, calorimetry, kinetics, and electrochemistry. Software considerations and laboratory procedures are discussed. (CW)

The acid-base buffer capacity of podzolic soils and its changes under the impact of treatment with the Mehra-Jackson and Tamm reagents

NASA Astrophysics Data System (ADS)

Maksimova, Yu. G.; Maryakhina, N. N.; Tolpeshta, I. I.; Sokolova, T. A.

2010-10-01

The acid-base buffer capacity before and after the treatment with the Mehra-Jackson and Tamm reagents was assessed by continuous potentiometric titration for the main genetic horizons of two profiles of podzolic soils in the Central Forest State Reserve. The total buffer capacity was calculated in the pH range from the initial titration point (ITP) to 3 for the acid titration and from the ITP to 10 for the base titration, as well as the buffer capacities in the pH intervals of 0.25. It was found that both treatments abruptly decreased the base buffer capacity, which reached 70-90% in the E horizons. The high direct linear correlation of the difference between the total base buffer capacities before and after each treatment with the content of Fe in the Tamm extract was revealed. From the results obtained, a conclusion was drawn that finely dispersed Fe hydroxides were the main solid-phase constituents ensuring the base buffer capacity, and the deprotonation of hydroxyl groups on the surface of Fe hydroxides was the essential buffer reaction during the base titration.

GKI chloride in water, analysis method. GKI boron in water, analysis method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morriss, L.L.

1979-05-01

Procedures for the chemical analysis of chlorides and boron in water are presented. Chlorides can be titrated with mercuric nitrate to form mercuric chloride. At pH 2.3 to 2.8, diphenylcarbazone indicates the end point of this titration by formation of a purple complex with mercury ions. When a sample of water containing boron is acidified and evaporated in the presence of curcumin, a red colored product called rosocyanine is formed. This is dissolved and can be measured photometrically or visually. (DMC)

Iron Analysis by Redox Titration. A General Chemistry Experiment.

ERIC Educational Resources Information Center

Kaufman, Samuel; DeVoe, Howard

1988-01-01

Describes a simplified redox method for total iron analysis suitable for execution in a three-hour laboratory period by general chemistry students. Discusses materials, procedures, analyses, and student performance. (CW)

Concentration determination of methyl magnesium chloride and other Grignard reagents by potentiometric titration with in-line characterization of reaction species by FTIR spectroscopy.

PubMed

Chen, Yadan; Wang, Tao; Helmy, Roy; Zhou, George X; LoBrutto, Rosario

2002-07-01

A potentiometric titration method for methyl magnesium chloride and other Grignard reagents based on the reaction with 2-butanol in THF has been developed and validated. The method employs a commercially available platinum electrode, using an electrolyte compatible with non-aqueous solvents. Well-defined titration curves were obtained, along with excellent method precision. The endpoint was precisely determined based on the first derivative of the titration curve. Different solvents such as THF, diethyl ether and methylene chloride provided similar results with regard to sharpness of the endpoint and method precision. The method was applied to a wide array of Grignard reagents including methyl magnesium bromide, ethyl magnesium chloride, propyl magnesium chloride, vinyl magnesium chloride, phenyl magnesium chloride, and benzyl magnesium chloride with similar precision and accuracy. Application of in-line FTIR was demonstrated for in situ monitoring of the titration reaction, allowing characterization of the reaction species. An authentic spectrum of the MeMgCl-THF complex was obtained using spectral subtraction and the vibrational absorbance bands were identified. FTIR also provided an alternative for detecting the titration endpoint, and the titration results so obtained, provided a cross-validation of the accuracy of the potentiometric titration.

Potentiometric titration and equivalent weight of humic acid

USGS Publications Warehouse

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

1960-01-01

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

A digital image-based method for determining of total acidity in red wines using acid-base titration without indicator.

PubMed

Tôrres, Adamastor Rodrigues; Lyra, Wellington da Silva; de Andrade, Stéfani Iury Evangelista; Andrade, Renato Allan Navarro; da Silva, Edvan Cirino; Araújo, Mário César Ugulino; Gaião, Edvaldo da Nóbrega

2011-05-15

This work proposes the use of digital image-based method for determination of total acidity in red wines by means of acid-base titration without using an external indicator or any pre-treatment of the sample. Digital images present the colour of the emergent radiation which is complementary to the radiation absorbed by anthocyanines present in wines. Anthocyanines change colour depending on the pH of the medium, and from the variation of colour in the images obtained during titration, the end point can be localized with accuracy and precision. RGB-based values were employed to build titration curves, and end points were localized by second derivative curves. The official method recommends potentiometric titration with a NaOH standard solution, and sample dilution until the pH reaches 8.2-8.4. In order to illustrate the feasibility of the proposed method, titrations of ten red wines were carried out. Results were compared with the reference method, and no statistically significant difference was observed between the results by applying the paired t-test at the 95% confidence level. The proposed method yielded more precise results than the official method. This is due to the trivariate nature of the measurements (RGB), associated with digital images. Copyright © 2011 Elsevier B.V. All rights reserved.

A potentiometric titration method for the crystallization of drug-like organic molecules.

PubMed

Du-Cuny, Lei; Huwyler, Jörg; Fischer, Holger; Kansy, Manfred

2007-09-05

It is generally accepted, that crystalline solids representing a low energy polymorph should be selected for development of oral dosage forms. As a consequence, efficient and robust procedures are needed at an early stage during drug discovery to prepare crystals from drug-like organic molecules. In contrast to the use of supersaturated solutions, we present a potentiometric crystallization procedure where saturated solutions are prepared in a controlled manner by pH-titration. Crystallization is carried out under defined conditions using the sample concentration and experimental pK(a) values as input parameters. Crystals of high quality were obtained for 11 drugs selected to demonstrate the efficiency and applicability of the new method. Technical improvements are suggested to overcome practical limitations and to enhance the possibility of obtaining crystals from molecules in their uncharged form.

A semi-grand canonical Monte Carlo simulation model for ion binding to ionizable surfaces: proton binding of carboxylated latex particles as a case study.

PubMed

Madurga, Sergio; Rey-Castro, Carlos; Pastor, Isabel; Vilaseca, Eudald; David, Calin; Garcés, Josep Lluís; Puy, Jaume; Mas, Francesc

2011-11-14

In this paper, we present a computer simulation study of the ion binding process at an ionizable surface using a semi-grand canonical Monte Carlo method that models the surface as a discrete distribution of charged and neutral functional groups in equilibrium with explicit ions modelled in the context of the primitive model. The parameters of the simulation model were tuned and checked by comparison with experimental titrations of carboxylated latex particles in the presence of different ionic strengths of monovalent ions. The titration of these particles was analysed by calculating the degree of dissociation of the latex functional groups vs. pH curves at different background salt concentrations. As the charge of the titrated surface changes during the simulation, a procedure to keep the electroneutrality of the system is required. Here, two approaches are used with the choice depending on the ion selected to maintain electroneutrality: counterion or coion procedures. We compare and discuss the difference between the procedures. The simulations also provided a microscopic description of the electrostatic double layer (EDL) structure as a function of pH and ionic strength. The results allow us to quantify the effect of the size of the background salt ions and of the surface functional groups on the degree of dissociation. The non-homogeneous structure of the EDL was revealed by plotting the counterion density profiles around charged and neutral surface functional groups. © 2011 American Institute of Physics

Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method.

PubMed

Black, Stuart; Ferrell, Jack R

2017-02-07

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Additionally, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. While traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 °C.

Isolating behavioral mechanisms of intertemporal choice: nicotine effects on delay discounting and amount sensitivity.

PubMed

Locey, Matthew L; Dallery, Jesse

2009-03-01

Many drugs of abuse produce changes in impulsive choice, that is, choice for a smaller-sooner reinforcer over a larger-later reinforcer. Because the alternatives differ in both delay and amount, it is not clear whether these drug effects are due to the differences in reinforcer delay or amount. To isolate the effects of delay, we used a titrating delay procedure. In phase 1, 9 rats made discrete choices between variable delays (1 or 19 s, equal probability of each) and a delay to a single food pellet. The computer titrated the delay to a single food pellet until the rats were indifferent between the two options. This indifference delay was used as the starting value for the titrating delay for all future sessions. We next evaluated the acute effects of nicotine (subcutaneous 1.0, 0.3, 0.1, and 0.03 mg/kg) on choice. If nicotine increases delay discounting, it should have increased preference for the variable delay. Instead, nicotine had very little effect on choice. In a second phase, the titrated delay alternative produced three food pellets instead of one, which was again produced by the variable delay (1 s or 19 s) alternative. Under this procedure, nicotine increased preference for the one pellet alternative. Nicotine-induced changes in impulsive choice are therefore likely due to differences in reinforcer amount rather than differences in reinforcer delay. In addition, it may be necessary to include an amount sensitivity parameter in any mathematical model of choice when the alternatives differ in reinforcer amount.

Benefit of slow titration of paroxetine to treat depression in the elderly.

PubMed

Olgiati, Paolo; Bajo, Emanuele; Serretti, Alessandro

2014-11-01

Paroxetine is commonly used to treat depression in the elderly; however, titration issues have been raised. Rapid titration may lead to increased anxiety and early dropout. The aim of this cost-utility analysis was to compare the potential benefit of standard (10 mg the first day) versus slow titration (2.5 mg gradually increased). Clinical analysis was based on a naturalistic trial integrated with a decision-analytic model representing second treatments for those who initially did not respond and for dropout cases. Treatment setting was a public outpatient center for mental disorders in Italy. Service use data were estimated from best practice guidelines, whereas costs (Euros; 2012) were retrieved from Italian official sources. Slow titration approach produced 0.031 more quality-adjusted life years (remission rate: 57% vs 44% in standard titration group) at an incremental cost of €5.53 (generic paroxetine) and €54.54 (brand paroxetine syrup). Incremental cost-effectiveness ratio (ICER) values were €159 and €1768, respectively, in favor of slow titration approach. Cost-effectiveness threshold, defined as ICER < 1 GDP per capita according to World Health Organization criteria, is about €25 000 in Italy. Our results are consistent with a superiority of slow titration of paroxetine in older depressed patients. However, these findings, in part based on simulated data, need to be replicated in clinical trials. Copyright © 2014 John Wiley & Sons, Ltd.

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

PubMed

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

2005-06-01

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.

Determination of the titratable acidity and the pH of wine based on potentiometric flow injection analysis.

PubMed

Vahl, Katja; Kahlert, Heike; von Mühlen, Lisandro; Albrecht, Anja; Meyer, Gabriele; Behnert, Jürgen

2013-07-15

A FIA system using a pH-sensitive detector based on a graphite/quinhydrone/silicone composite electrode was applied to determine sequentially the titratable acidity and the pH of wine, as well as the sum of calcium and magnesium ions. For all measurements the same FIA configuration was used employing different carrier solutions. The results for the determination of acidity and pH are in good agreement with those obtained by classical potentiometric titrations and by pH measurements using a conventional glass electrode. The standard deviation was less than 1.5% for both kinds of measurements and the sample volume was 150 μL. The method allows about 40 determinations of titratable acidity per hour and 30 pH measurements per hour. The titration method can be adjusted to the legal requirements in USA and Europe. Copyright © 2013 Elsevier B.V. All rights reserved.

A rigorous multiple independent binding site model for determining cell-based equilibrium dissociation constants.

PubMed

Drake, Andrew W; Klakamp, Scott L

2007-01-10

A new 4-parameter nonlinear equation based on the standard multiple independent binding site model (MIBS) is presented for fitting cell-based ligand titration data in order to calculate the ligand/cell receptor equilibrium dissociation constant and the number of receptors/cell. The most commonly used linear (Scatchard Plot) or nonlinear 2-parameter model (a single binding site model found in commercial programs like Prism(R)) used for analysis of ligand/receptor binding data assumes only the K(D) influences the shape of the titration curve. We demonstrate using simulated data sets that, depending upon the cell surface receptor expression level, the number of cells titrated, and the magnitude of the K(D) being measured, this assumption of always being under K(D)-controlled conditions can be erroneous and can lead to unreliable estimates for the binding parameters. We also compare and contrast the fitting of simulated data sets to the commonly used cell-based binding equation versus our more rigorous 4-parameter nonlinear MIBS model. It is shown through these simulations that the new 4-parameter MIBS model, when used for cell-based titrations under optimal conditions, yields highly accurate estimates of all binding parameters and hence should be the preferred model to fit cell-based experimental nonlinear titration data.

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

Code of Federal Regulations, 2010 CFR

2010-07-01

... Method A Appendix A to Part 425 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The potassium ferricyanide titration method is based on method SLM 4/2 described in “Official Method of Analysis,” Society of Leather Trades...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... Method A Appendix A to Part 425 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED..., App. A Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The potassium ferricyanide titration method is based on method SLM 4/2 described in “Official Method of Analysis,” Society of...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... Method A Appendix A to Part 425 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The potassium ferricyanide titration method is based on method SLM 4/2 described in “Official Method of Analysis,” Society of Leather Trades...

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

PubMed Central

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

2016-01-01

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

Calculation of the acid-base equilibrium constants at the alumina/electrolyte interface from the ph dependence of the adsorption of singly charged ions (Na+, Cl-)

NASA Astrophysics Data System (ADS)

Gololobova, E. G.; Gorichev, I. G.; Lainer, Yu. A.; Skvortsova, I. V.

2011-05-01

A procedure was proposed for the calculation of the acid-base equilibrium constants at an alumina/electrolyte interface from experimental data on the adsorption of singly charged ions (Na+, Cl-) at various pH values. The calculated constants (p K {1/0}= 4.1, p K {2/0}= 11.9, p K {3/0}= 8.3, and p K {4/0}= 7.7) are shown to agree with the values obtained from an experimental pH dependence of the electrokinetic potential and the results of potentiometric titration of Al2O3 suspensions.

A Microscale Spectrophotometric Determination of Water Hardness

NASA Astrophysics Data System (ADS)

Gordon, James S.

2001-08-01

A spectrophotometric titration was performed to determine water hardness. The titration incorporated the traditional titration method employing EDTA as the titrant and calmagite as the indicator. The microscale experiment was carried out in a spectrometer cuvette and made use of a Texas Instruments (TI-83) calculator interfaced through a TI Calculator-Based Laboratory system to a Vernier colorimeter as the detector. Monitoring at 635 nm, one of the colorimeter's fixed wavelengths, was well suited for this analysis. Agreement was found with results from traditional titrations.

Rapid analytical determination of glutaraldehyde concentrations

NASA Technical Reports Server (NTRS)

Frigerio, N. A.; Shaw, M. H.

1971-01-01

Technique utilizes the iodimetric procedure which adds unknown excess of bisulfite to glutaraldehyde /GA/ then titrates unreacted bisulfite with standard iodine isotope to determine GA concentrations. Technique may interest microscopists, food researchers, biochemical or medical laboratories, and drug manufacturers.

Titration of individual strains in trivalent live-attenuated influenza vaccine without neutralization.

PubMed

Sirinonthanawech, Naraporn; Surichan, Somchaiya; Namsai, Aphinya; Puthavathana, Pilaipan; Auewarakul, Prasert; Kongchanagul, Alita

2016-11-01

Formulation and quality control of trivalent live-attenuated influenza vaccine requires titration of infectivity of individual strains in the trivalent mix. This is usually performed by selective neutralization of two of the three strains and titration of the un-neutralized strain in cell culture or embryonated eggs. This procedure requires standard sera with high neutralizing titer against each of the three strains. Obtaining standard sera, which can specifically neutralize only the corresponding strain of influenza viruses and is able to completely neutralize high concentration of virus in the vaccine samples, can be a problem for many vaccine manufacturers as vaccine stocks usually have very high viral titers and complete neutralization may not be obtained. Here an alternative approach for titration of individual strain in trivalent vaccine without the selective neutralization is presented. This was done by detecting individual strains with specific antibodies in an end-point titration of a trivalent vaccine in cell culture. Similar titers were observed in monovalent and trivalent vaccines for influenza A H3N2 and influenza B strains, whereas the influenza A H1N1 strain did not grow well in cell culture. Viral interference among the vaccine strains was not observed. Therefore, providing that vaccine strains grow well in cell culture, this assay can reliably determine the potency of individual strains in trivalent live-attenuated influenza vaccines. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of Titratable Acidity in Wine Using Potentiometric, Conductometric, and Photometric Methods

ERIC Educational Resources Information Center

Volmer, Dietrich A.; Curbani, Luana; Parker, Timothy A.; Garcia, Jennifer; Schultz, Linda D.; Borges, Endler Marcel

2017-01-01

This experiment describes a simple protocol for teaching acid-base titrations using potentiometry, conductivity, and/or photometry to determine end points without an added indicator. The chosen example examines the titratable acidity of a red wine with NaOH. Wines contain anthocyanins, the colors of which change with pH. Importantly, at the…

Using Spreadsheets to Produce Acid-Base Titration Curves.

ERIC Educational Resources Information Center

Cawley, Martin James; Parkinson, John

1995-01-01

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

Efficacy and safety of weight-based insulin glargine dose titration regimen compared with glucose level- and current dose-based regimens in hospitalized patients with type 2 diabetes: a randomized, controlled study.

PubMed

Li, Xiaowei; Du, Tao; Li, Wangen; Zhang, Tong; Liu, Haiyan; Xiong, Yifeng

2014-09-01

Insulin glargine is widely used as basal insulin. However, published dose titration regimens for insulin glargine are complex. This study aimed to compare the efficacy and safety profile of a user-friendly, weight-based insulin glargine dose titration regimen with 2 published regimens. A total of 160 hospitalized patients with hyperglycemia in 3 medical centers were screened. Our inclusion criteria included age 18 to 80 years and being conscious. Exclusion criteria included pregnancy or breast-feeding and hepatic or renal dysfunction. A total of 149 patients were randomly assigned to receive weight-based, glucose level-based, or dose-based insulin glargine dose titration regimen between January 2011 and February 2013. The initial dose of insulin glargine was 0.2 U/kg. In the weight-based regimen (n = 49), the dose was titrated by increments of 0.1 U/kg daily. In the glucose level-based regimen (n = 51), the dose was titrated by 2, 4, 6, or 8 U daily when fasting blood glucose (FBG) was, respectively, between 7.0 and 7.9, 8.0 and 8.9, 9.0 and 9.9, or ≥10 mmol/L. In the current dose-based regimen (n = 49), titration was by daily increments of 20% of the current dose. The target FBG in all groups was ≤7.0 mmol/L. The incidence of hypoglycemia was recorded. One-way ANOVA and χ(2) test were used to compare data between the 3 groups. All but 1 patient who required additional oral antidiabetic medication completed the study. The mean (SD) time to achieve target FBG was 3.2 (1.2) days with the weight-based regimen and 3.7 (1.5) days with the glucose level-based regimen (P = 0.266). These times were both shorter than that achieved with the current dose-based regimen (4.8 [2.8] days; P = 0.0001 and P = 0.005, respectively). The daily doses of insulin glargine at the study end point were 0.43 (0.13) U/kg with the weight-based regimen, 0.50 (0.20) U/kg with the glucose level-based regimen, and 0.47 (0.23) U/kg with the current dose-based regimen (P = 0.184). The incidence of hypoglycemia was 4.1%, 2.0%, and 6.3%, respectively (P = 0.557). The currently proposed weight-based insulin glargine dose titration regimen is effective, tolerable, and user-friendly at achieving FBG target levels in hospitalized patients with hyperglycemia. Copyright © 2014 Elsevier HS Journals, Inc. All rights reserved.

The Exchange.

ERIC Educational Resources Information Center

Blain, Mary P., Ed.; Pintavalle, Steven J., Ed.

1985-01-01

Presents 10 activities in biology, chemistry, physical science, and general science. Activities focus on: alfalfa sprouts; soap test; density; skating on cold ice; Kirlian photography; titration analysis (with program listing); radioactive decay; and others. Each activity includes suggested grade level(s) and procedures. (DH)

An Empirical Formula From Ion Exchange Chromatography and Colorimetry.

ERIC Educational Resources Information Center

Johnson, Steven D.

1996-01-01

Presents a detailed procedure for finding an empirical formula from ion exchange chromatography and colorimetry. Introduces students to more varied techniques including volumetric manipulation, titration, ion-exchange, preparation of a calibration curve, and the use of colorimetry. (JRH)

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

PubMed

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

2008-09-01

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

Kinetics of bacterial potentiometric titrations: the effect of equilibration time on buffering capacity of Pantoea agglomerans suspensions.

PubMed

Kapetas, Leon; Ngwenya, Bryne T; Macdonald, Alan M; Elphick, Stephen C

2011-07-15

Several recent studies have made use of continuous acid-base titration data to describe the surface chemistry of bacterial cells as a basis for accurately modelling metal adsorption to bacteria and other biomaterials of potential industrial importance. These studies do not share a common protocol; rather they titrate in different pH ranges and they use different stability criteria to define equilibration time during titration. In the present study we investigate the kinetics of bacterial titrations and test the effect they have on the derivation of functional group concentrations and acidity constants. We titrated suspensions of Pantoea agglomerans by varying the equilibration time between successive titrant additions until stability of 0.1 or 0.001 mV s(-1) was attained. We show that under longer equilibration times, titration results are less reproducible and suspensions exhibit marginally higher buffering. Fluorescence images suggest that cell lysis is not responsible for these effects. Rather, high DOC values and titration reversibility hysterisis after long equilibration times suggest that variability in buffering is due to the presence of bacterial exudates, as demonstrated by titrating supernatants separated from suspensions of different equilibration times. It is recommended that an optimal equilibration time is always determined with variable stability control and preliminary reversibility titration experiments. Copyright © 2011 Elsevier Inc. All rights reserved.

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

ERIC Educational Resources Information Center

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

2004-01-01

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

Integration and global analysis of isothermal titration calorimetry data for studying macromolecular interactions.

PubMed

Brautigam, Chad A; Zhao, Huaying; Vargas, Carolyn; Keller, Sandro; Schuck, Peter

2016-05-01

Isothermal titration calorimetry (ITC) is a powerful and widely used method to measure the energetics of macromolecular interactions by recording a thermogram of differential heating power during a titration. However, traditional ITC analysis is limited by stochastic thermogram noise and by the limited information content of a single titration experiment. Here we present a protocol for bias-free thermogram integration based on automated shape analysis of the injection peaks, followed by combination of isotherms from different calorimetric titration experiments into a global analysis, statistical analysis of binding parameters and graphical presentation of the results. This is performed using the integrated public-domain software packages NITPIC, SEDPHAT and GUSSI. The recently developed low-noise thermogram integration approach and global analysis allow for more precise parameter estimates and more reliable quantification of multisite and multicomponent cooperative and competitive interactions. Titration experiments typically take 1-2.5 h each, and global analysis usually takes 10-20 min.

Determination of arsenate and organic arsenic via potentiometric titration of its heteropoly anions.

PubMed

Metelka, R; Slavíková, S; Vytras, K

2002-08-16

Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption versus concentration of arsenic were constructed and used to evaluate the content of arsenic in aqueous samples. The method could be applied in the analyses of samples with quite low arsenic content (amounts approximately 10 mug As in 50 cm(3) could be titrated). Organic arsenic was determined analogously after the Schöniger combustion of the sample and conversion of its arsenic to arsenate.

Comparative study of titrated oral misoprostol solution and vaginal dinoprostone for labor induction at term pregnancy.

PubMed

Wang, Xiu; Yang, Aijun; Ma, Qingyong; Li, Xuelan; Qin, Li; He, Tongqiang

2016-09-01

To evaluate effectiveness and safety of titrated oral misoprostol solution (OMS) in comparison with vaginal dinoprostone for cervix ripening and labor induction in term pregnant women. A multicenter randomized controlled trial of women with term singleton pregnancy with indications for labor induction; 481 participants were allocated to receive titrated OMS with different doses by hourly administration according to the procedure or insert vaginal dinoprostone for cervix ripening and labor induction to compare maternal outcomes including indication of labor induction, mode of outcome of delivery, maternal morbidity, and neonatal outcomes between two groups for evaluating the efficacy and safety of titrated oral misoprostol induction. Proportion of delivery within 12 h of titrated oral misoprostol is significantly less than vaginal dinoprostone (p = 0.03), but no difference of total vaginal delivery rate (p = 0.93); the mean time of first treatment to vaginal delivery was longer in OMS group (21.3 ± 14.5 h) compared with the vaginal dinoprostone group (15.7 ± 9.6 h). Although the proportion of cesarean section between the two groups showed no statistically significant difference, OMS group showed significantly lower frequency of uterine hyperstimulation, hypertonus, partus precipitatus and non-reassuring fetal heart rate than dinoprostone group. Neonatal outcomes were similar evaluating from Apgar score and NICU admission. Our study also showed that labor induction of women with cervix Bishop score ≤3 needed increased dosage of misoprostol solution. Titrated OMS is as effective as vaginal dinoprostone in labor induction for term pregnant women, with safer effect for its lower rate of adverse effect for women.

Determining the folding and binding free energy of DNA-based nanodevices and nanoswitches using urea titration curves

PubMed Central

Idili, Andrea

2017-01-01

Abstract DNA nanotechnology takes advantage of the predictability of DNA interactions to build complex DNA-based functional nanoscale structures. However, when DNA functional and responsive units that are based on non-canonical DNA interactions are employed it becomes quite challenging to predict, understand and control their thermodynamics. In response to this limitation, here we demonstrate the use of isothermal urea titration experiments to estimate the free energy involved in a set of DNA-based systems ranging from unimolecular DNA-based nanoswitches to more complex DNA folds (e.g. aptamers) and nanodevices. We propose here a set of fitting equations that allow to analyze the urea titration curves of these DNA responsive units based on Watson–Crick and non-canonical interactions (stem-loop, G-quadruplex, triplex structures) and to correctly estimate their relative folding and binding free energy values under different experimental conditions. The results described herein will pave the way toward the use of urea titration experiments in the field of DNA nanotechnology to achieve easier and more reliable thermodynamic characterization of DNA-based functional responsive units. More generally, our results will be of general utility to characterize other complex supramolecular systems based on different biopolymers. PMID:28605461

Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

ERIC Educational Resources Information Center

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

2016-01-01

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

Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Black, Stuart; Ferrell, Jack R.

We know that carbonyl compounds, present in bio-oils, are responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. In addition, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation havemore » long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. And while traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 degrees C.« less

[Determination of total protein content in soya-bean milk via visual moving reaction boundary titration].

PubMed

Guo, Chengye; Wang, Houyu; Zhang, Lei; Fan, Liuyin; Cao, Chengxi

2013-11-01

A visual, rapid and accurate moving reaction boundary titration (MRBT) method was used for the determination of the total protein in soya-bean milk. During the process, moving reaction boundary (MRB) was formed by hydroxyl ions in the catholyte and soya-bean milk proteins immobilized in polyacrylamide gel (PAG), and an acid-base indicator was used to denote the boundary motion. The velocity of MRB has a relationship with protein concentration, which was used to obtain a standard curve. By paired t-test, there was no significant difference of the protein content between MRBT and Kjeldahl method at 95% confidence interval. The procedure of MRBT method required about 10 min, and it had linearity in the range of 2.0-14.0 g/L, low limit of detection (0.05 g/L), good precision (RSD of intra-day < 1.90% and inter-day < 4.39%), and high recoveries (97.41%-99.91%). In addition, non-protein nitrogen (NPN) such as melamine added into the soya-bean milk had weak influence on MRBT results.

Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

DOE PAGES

Black, Stuart; Ferrell, Jack R.

2017-02-07

We know that carbonyl compounds, present in bio-oils, are responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. In addition, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation havemore » long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. And while traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 degrees C.« less

Consensus on Insulin Dose and Titration Algorithms in Ambulatory Care of Type 2 Diabetes in India.

PubMed

Kovil, Rajiv; Chawla, Manoj; Rajput, Rajesh; Singh, A K; Sinha, Binayak; Ghosal, Samit; Ballani, Piya; Gupta, Sunil; Tanna, Snehal; Bandukwala, S M; Shah, Tejas; Negalur, Vijay; Bhoraskar, Anil; Aravind, S R; Zargar, Abdul H; Kesavadev, Jothydev; Das, Ashok Kumar

2017-02-01

Insulin is the oldest of the currently available treatment options in Type 2 diabetes mellitus (T2DM) and is considered as the most effective glucose lowering agent. Despite this, decision on starting insulin therapy is often delayed in India as well as worldwide due to various barriers at both patient and physician levels. Appropriate insulin dosing and titration is also critical to the successful achievement of tight glycaemic control. To provide simple and easily implementable guidelines to primary care physicians on appropriate insulin dosing and titration of various insulin regimens for both initiation and intensification. Each insulin regimen (once daily [OD] basal, OD, twice daily and thrice daily premixed, basal-plus and basal-bolus) was presented and evaluated for dosing and titration based on established guidelines, data from approved pack inserts, and published scientific literature. These evaluations were then factored into the national context based on the expert committee representatives patient-physician experience in their clinical practice and common therapeutic practices followed in India. Recommendations for dosing and titration of basal, basal-plus, premixed and basal-bolus insulins were developed. The key recommendations are that insulin doses can be adjusted once or twice weekly; adjustment can be based on lowest/mean of three recent self-monitoring of plasma glucose pre-meal/fasting plasma glucose (FPG) values. The titration should be based on FPG or pre-meal value of 80-130 mg/dL and the dose should be reduced by 10-20% for patients reporting hypoglycaemia(<70mg/dL). The consensus based recommendations mentioned in this paper will be a useful reference tool for health care practitioners, to initiate, optimise and intensify insulin therapy and to successfully achieve optimal glucose control.

Effect of temperature on the acid-base properties of the alumina surface: microcalorimetry and acid-base titration experiments.

PubMed

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

2006-06-15

Sorption reactions on natural or synthetic materials that can attenuate the migration of pollutants in the geosphere could be affected by temperature variations. Nevertheless, most of the theoretical models describing sorption reactions are at 25 degrees C. To check these models at different temperatures, experimental data such as the enthalpies of sorption are thus required. Highly sensitive microcalorimeters can now be used to determine the heat effects accompanying the sorption of radionuclides on oxide-water interfaces, but enthalpies of sorption cannot be extracted from microcalorimetric data without a clear knowledge of the thermodynamics of protonation and deprotonation of the oxide surface. However, the values reported in the literature show large discrepancies and one must conclude that, amazingly, this fundamental problem of proton binding is not yet resolved. We have thus undertaken to measure by titration microcalorimetry the heat effects accompanying proton exchange at the alumina-water interface at 25 degrees C. Based on (i) the surface sites speciation provided by a surface complexation model (built from acid-base titrations at 25 degrees C) and (ii) results of the microcalorimetric experiments, calculations have been made to extract the enthalpic variations associated respectively to first and second deprotonation of the alumina surface. Values obtained are deltaH1 = 80+/-10 kJ mol(-1) and deltaH2 = 5+/-3 kJ mol(-1). In a second step, these enthalpy values were used to calculate the alumina surface acidity constants at 50 degrees C via the van't Hoff equation. Then a theoretical titration curve at 50 degrees C was calculated and compared to the experimental alumina surface titration curve. Good agreement between the predicted acid-base titration curve and the experimental one was observed.

Insights into energy delivery to myocardial tissue during radiofrequency ablation through application of the first law of thermodynamics.

PubMed

Bunch, T Jared; Day, John D; Packer, Douglas L

2009-04-01

The approach to catheter-based radiofrequency ablation of atrial fibrillation has evolved, and as a consequence, more energy is delivered in the posterior left atrium, exposing neighboring tissue to untoward thermal injury. Simultaneously, catheter technology has advanced to allow more efficient energy delivery into the myocardium, which compounds the likelihood of collateral injury. This review focuses on the basic principles of thermodynamics as they apply to energy delivery during radiofrequency ablation. These principles can be used to titrate energy delivery and plan ablative approaches in an effort to minimize complications during the procedure.

Amperometric, Bipotentiometric, and Coulometric Titration.

ERIC Educational Resources Information Center

Stock, John T.

1980-01-01

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

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

PubMed

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

2008-06-01

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. Denaturation temperature for this enzyme was calculated using analysis of the proportion of stabilizing and destabilizing amino acids in the molecule.

Process monitored spectrophotometric titration coupled with chemometrics for simultaneous determination of mixtures of weak acids.

PubMed

Liao, Lifu; Yang, Jing; Yuan, Jintao

2007-05-15

A new spectrophotometric titration method coupled with chemometrics for the simultaneous determination of mixtures of weak acids has been developed. In this method, the titrant is a mixture of sodium hydroxide and an acid-base indicator, and the indicator is used to monitor the titration process. In a process of titration, both the added volume of titrant and the solution acidity at each titration point can be obtained simultaneously from an absorption spectrum by least square algorithm, and then the concentration of each component in the mixture can be obtained from the titration curves by principal component regression. The method only needs the information of absorbance spectra to obtain the analytical results, and is free of volumetric measurements. The analyses are independent of titration end point and do not need the accurate values of dissociation constants of the indicator and the acids. The method has been applied to the simultaneous determination of the mixtures of benzoic acid and salicylic acid, and the mixtures of phenol, o-chlorophenol and p-chlorophenol with satisfactory results.

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

PubMed

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

2005-10-15

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

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

PubMed

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

2014-01-01

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.

Reduction and determination of dixanthogens.

PubMed

Prasad, M S

1971-06-01

A convenient method for the reduction and determination of dixaathogen has been developed. It is based on the quantitative reaction of dixanthogen with zinc amalgam to form xanthate; the latter can be determined by iodine titration, potentiometric titration with silver nitrate or by spectrophotometry at 310 mmu. Dixanthogen can be determined in mixtures containing xanthate, by titration of aliquots with and without reduction. Higher dixanthogens can also be determined, and flotation liquors analysed.

Methods for collection and analysis of geopressured geothermal and oil field waters

USGS Publications Warehouse

Lico, Michael S.; Kharaka, Yousif K.; Carothers, William W.; Wright, Victoria A.

1982-01-01

Present methods are described for the collection, preservation, and chemical analysis of waters produced from geopressured geothermal and petroleum wells. Detailed procedures for collection include precautions and equipment necessary to ensure that the sample is representative of the water produced. Procedures for sample preservation include filtration, acidification, dilution for silica, methyl isobutyl ketone (MIBK) extraction of aluminum, addition of potassium permanganate to preserve mercury, and precipitation of carbonate species as strontium carbonate for stable carbon isotopes and total dissolved carbonate analysis. Characteristics determined at the well site are sulfide, pH, ammonia, and conductivity. Laboratory procedures are given for the analysis of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, iron, manganese, zinc, lead, aluminum, .and mercury by atomic absorption and flame emission spectroscopy. Chloride is determined by silver nitrate titration and fluoride by ion-specific electrode. Bromide and iodide concentrations are determined by the hypochlorite oxidation method. Sulfate is analyzed by titration using barium chloride with thorin indicator after pretreatment with alumina. Boron and silica are determined colorimetrically by the carmine and molybdate-blue methods, respectively. Aliphatic acid anions (C2 through C5) are determined by gas chromatography after separation and concentration in a chloroform-butanol mixture.

Determination of the total acidity in soft drinks using potentiometric sequential injection titration.

PubMed

van Staden, J Koos F; Mashamba, M Mulalo G; Stefan, R Raluca I

2002-12-06

A potentiometric SI titration system for the determination of total acidity in soft drinks is proposed. The concept is based on the aspiration of the acid soft drink sample between two base zones into a holding coil with the volume of the first base zone twice to that of the second one and channelled by flow reversal through a reaction coil to a potentiometric sensor. A solution of 0.1 mol l(-1) sodium chloride is used as ionic strength adjustment buffer in the carrier stream. The system has been applied to the analysis of some South African soft drinks having a total acidity level of about 0.2-0.3% (w/v). The method has a sample frequency of 45 samples per h with a linear range of 0.1 and 0.6% (w/v). It is easy to use, fully computerised, and gives the results that are comparable to both automated batch titration and manual titration.

Spectroscopic study on variations in illite surface properties after acid-base titration.

PubMed

Liu, Wen-xin; Coveney, R M; Tang, Hong-xiao

2003-07-01

FT-IR, Raman microscopy, XRD, 29Si and 27Al MAS NMR, were used to investigate changes in surface properties of a natural illite sample after acid-base potentiometric titration. The characteristic XRD lines indicated the presence of surface Al-Si complexes, preferable to Al(OH)3 precipitates. In the microscopic Raman spectra, the vibration peaks of Si-O and Al-O bonds diminished as a result of treatment with acid, then increased after hydroxide back titration. The varied ratio of signal intensity between (IV)Al and (VI)Al species in 27Al MAS NMR spectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure of illite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illite surfaces and acid-leaching silicic acid and aluminum ions should be considered in the model description of surface acid-base properties of the aqueous illite.

Old and new approaches to the interpretation of acid-base metabolism, starting from historical data applied to diabetic acidosis.

PubMed

Mioni, Roberto; Marega, Alessandra; Lo Cicero, Marco; Montanaro, Domenico

2016-11-01

The approach to acid-base chemistry in medicine includes several methods. Currently, the two most popular procedures are derived from Stewart's studies and from the bicarbonate/BE-based classical formulation. Another method, unfortunately little known, follows the Kildeberg theory applied to acid-base titration. By using the data produced by Dana Atchley in 1933, regarding electrolytes and blood gas analysis applied to diabetes, we compared the three aforementioned methods, in order to highlight their strengths and their weaknesses. The results obtained, by reprocessing the data of Atchley, have shown that Kildeberg's approach, unlike the other two methods, is consistent, rational and complete for describing the organ-physiological behavior of the hydrogen ion turnover in human organism. In contrast, the data obtained using the Stewart approach and the bicarbonate-based classical formulation are misleading and fail to specify which organs or systems are involved in causing or maintaining the diabetic acidosis. Stewart's approach, despite being considered 'quantitative', does not propose in any way the concept of 'an amount of acid' and becomes even more confusing, because it is not clear how to distinguish between 'strong' and 'weak' ions. As for Stewart's approach, the classical method makes no distinction between hydrogen ions managed by the intermediate metabolism and hydroxyl ions handled by the kidney, but, at least, it is based on the concept of titration (base-excess) and indirectly defines the concept of 'an amount of acid'. In conclusion, only Kildeberg's approach offers a complete understanding of the causes and remedies against any type of acid-base disturbance.

Simulation-Based Evaluation of Dose-Titration Algorithms for Rapid-Acting Insulin in Subjects with Type 2 Diabetes Mellitus Inadequately Controlled on Basal Insulin and Oral Antihyperglycemic Medications.

PubMed

Ma, Xiaosu; Chien, Jenny Y; Johnson, Jennal; Malone, James; Sinha, Vikram

2017-08-01

The purpose of this prospective, model-based simulation approach was to evaluate the impact of various rapid-acting mealtime insulin dose-titration algorithms on glycemic control (hemoglobin A1c [HbA1c]). Seven stepwise, glucose-driven insulin dose-titration algorithms were evaluated with a model-based simulation approach by using insulin lispro. Pre-meal blood glucose readings were used to adjust insulin lispro doses. Two control dosing algorithms were included for comparison: no insulin lispro (basal insulin+metformin only) or insulin lispro with fixed doses without titration. Of the seven dosing algorithms assessed, daily adjustment of insulin lispro dose, when glucose targets were met at pre-breakfast, pre-lunch, and pre-dinner, sequentially, demonstrated greater HbA1c reduction at 24 weeks, compared with the other dosing algorithms. Hypoglycemic rates were comparable among the dosing algorithms except for higher rates with the insulin lispro fixed-dose scenario (no titration), as expected. The inferior HbA1c response for the "basal plus metformin only" arm supports the additional glycemic benefit with prandial insulin lispro. Our model-based simulations support a simplified dosing algorithm that does not include carbohydrate counting, but that includes glucose targets for daily dose adjustment to maintain glycemic control with a low risk of hypoglycemia.

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

PubMed

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

2011-01-01

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. 2011 © The Japan Society for Analytical Chemistry

Clozapine Titration for People in Early Psychosis: A Chart Review and Treatment Guideline.

PubMed

Ballon, Jacob S; Ashfaq, Hera; Noordsy, Douglas L

2018-06-01

The use of clozapine, particularly in young people, is often limited by early treatment-emergent adverse effects including drowsiness and lethargy. Concerns about adverse effects, medication adherence, and the need for blood monitoring often impede the use of clozapine in this population, leading to repeated trials of less effective medications. Current clozapine dosing recommendations are based on people further in the course of their illness and thus reflect different responsiveness and sensitivities to antipsychotic medication. As such, there is a need for evidence-based guidelines for titration and dosing of clozapine among people in early psychosis. We performed a chart review of 14 people treated with clozapine within our early psychosis team. Data regarding dose titration, response, time to discontinuation, symptom severity, weight gain, and other adverse effects were gathered at clozapine initiation, 3 months, and last available visit on clozapine. People treated with slow titration within their first year of psychosis onset achieved sustained response at very low maintenance doses (mean dose = 81 mg/d, mean duration of treatment = 200 weeks) compared with slow titration with longer duration of illness (mean dose = 350 mg/d, mean duration of treatment = 68 weeks) or standard dose titration in early psychosis (mean dose = 112 mg/d, mean duration of treatment = 38 weeks). The most common adverse effects in all groups were weight gain and sedation, with the groups requiring higher mean doses reporting a broader range of adverse effects. There was no apparent difference in the clinical global impression for severity or improvement between the slow titration and standard titration groups in people with early psychosis. These observations are synthesized into a proposed treatment guideline for use of clozapine among people in early psychosis. We describe development of a slow titration approach to initiating clozapine among people in early psychosis. This approach resulted in clinical response at remarkably low maintenance doses of clozapine among people within their first year of illness, but not in those with longer duration of symptoms. Slow titration also led to good tolerability and acceptance of clozapine treatment for some patients.

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

ERIC Educational Resources Information Center

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

2015-01-01

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

Mesoporous Carbons With Self-Assembled High-Activity Surfaces (PREPRINT)

DTIC Science & Technology

2006-07-07

temperature-programmed desorption, and potentiometric titrations . Journal of Colloid and Interface Science 2001; 240: 252–258. [40] Rotkin SV, Gogotsi Y...selected carbon samples were treated with nitric acid and the total acid site density determined by base titration [32-34 Boehm 1994; Boehm 2002; 32...washed thoroughly using distilled/deionized water, and dried in the oven. For the titration , 50 mg of HNO3-treated carbon powder was added to 20 ml

High-Molecular Compounds (Selected Articles).

DTIC Science & Technology

1987-10-15

us ions The method of potentiometric titration in dimethylformamide was used to study the structure of macro molecular chain of copolymers based on...macromolecular chain we used the method of potential metric titration . The objects of the study uere alpha chloroacrylic acid (KO)K) in monomer...homopolymer, and copolymer (with methylmethacrylate) form 131. I e d* r. I%0 I 0 12 # z Curves of potential metric titration of solutions of copolymers of KjAK

Process for Assessing the Stability of HAN (Hydroxylammonium Nitrate)-Based Liquid Propellants

DTIC Science & Technology

1989-02-09

Scholz, Guidelines by Messrs. Riedel - de Haen for Titration according to the Karl Fischer Method ), 3. Auflage/3rd Edition 1982 /22/ JANDER; G. and... Potentiometric determination of the equivalence point is the most suitable method /15/. Time is saved by using automatically recording titration 33...propellant. The water content of liquid propellants on the basis of HAN according to Fig. 6 can be determined directly by Karl Fischer titration. This

Amperometric, Bipotentiometric, and Coulometric Titration.

ERIC Educational Resources Information Center

Stock, John T.

1984-01-01

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

The predictive value of drug-induced sleep endoscopy for CPAP titration in OSA patients.

PubMed

Lan, Ming-Chin; Hsu, Yen-Bin; Lan, Ming-Ying; Huang, Yun-Chen; Kao, Ming-Chang; Huang, Tung-Tsun; Chiu, Tsan-Jen; Yang, Mei-Chen

2017-12-15

The aim of this study was to identify possible upper airway obstructions causing a higher continuous positive airway pressure (CPAP) titration level, utilizing drug-induced sleep endoscopy (DISE). A total of 76 patients with obstructive sleep apnea (OSA) underwent CPAP titration and DISE. DISE findings were recorded using the VOTE classification system. Polysomnographic (PSG) data, anthropometric variables, and patterns of airway collapse during DISE were analyzed with CPAP titration levels. A significant association was found between the CPAP titration level and BMI, oxygen desaturation index (ODI), apnea-hypopnea index (AHI), and neck circumference (NC) (P < 0.001, P < 0.001, P < 0.001, and P < 0.001, respectively, by Spearman correlation). Patients with concentric collapse of the velum or lateral oropharyngeal collapse were associated with a significantly higher CPAP titration level (P < 0.001 and P = 0.043, respectively, by nonparametric Mann-Whitney U test; P < 0.001 and P = 0.004, respectively, by Spearman correlation). No significant association was found between the CPAP titration level and any other collapse at the tongue base or epiglottis. By analyzing PSG data, anthropometric variables, and DISE results with CPAP titration levels, we can better understand possible mechanisms resulting in a higher CPAP titration level. We believe that the role of DISE can be expanded as a tool to identify the possible anatomical structures that may be corrected by oral appliance therapy or surgical intervention to improve CPAP compliance.

A model for oxygen conservation associated with titration during pediatric oxygen therapy.

PubMed

Wu, Grace; Wollen, Alec; Himley, Stephen; Austin, Glenn; Delarosa, Jaclyn; Izadnegahdar, Rasa; Ginsburg, Amy Sarah; Zehrung, Darin

2017-01-01

Continuous oxygen treatment is essential for managing children with hypoxemia, but access to oxygen in low-resource countries remains problematic. Given the high burden of pneumonia in these countries and the fact that flow can be gradually reduced as therapy progresses, oxygen conservation through routine titration warrants exploration. To determine the amount of oxygen saved via titration during oxygen therapy for children with hypoxemic pneumonia. Based on published clinical data, we developed a model of oxygen flow rates needed to manage hypoxemia, assuming recommended flow rate at start of therapy, and comparing total oxygen used with routine titration every 3 minutes or once every 24 hours versus no titration. Titration every 3 minutes or every 24 hours provided oxygen savings estimated at 11.7% ± 5.1% and 8.1% ± 5.1% (average ± standard error of the mean, n = 3), respectively. For every 100 patients, 44 or 30 kiloliters would be saved-equivalent to 733 or 500 hours at 1 liter per minute. Ongoing titration can conserve oxygen, even performed once-daily. While clinical validation is necessary, these findings could provide incentive for the routine use of pulse oximeters for patient management, as well as further development of automated systems.

Titrimetric Determination of Carbon Dioxide in a Heterogeneous Sample ("Pop Rocks")

NASA Astrophysics Data System (ADS)

Davis, Craig M.; Mauck, Matthew C.

2003-05-01

A traditional exercise in quantitative analysis is the titration of mixtures of sodium hydroxide, sodium carbonate, and sodium bicarbonate. Often, consumer products are studied. A procedure to analyze the total volume of carbon dioxide bubbles in the candy "Pop Rocks" is presented. The popularity of the sample and the simplicity of the procedure make this exercise suitable for a wide variety of students: from non-science majors to chemistry majors in a quantitative analysis course.

Risky Choice in Pigeons and Humans: A Cross-Species Comparison

ERIC Educational Resources Information Center

Lagorio, Carla H.; Hackenberg, Timothy D.

2010-01-01

Pigeon and human subjects were given repeated choices between variable and adjusting delays to token reinforcement that titrated in relation to a subject's recent choice patterns. Indifference curves were generated under two different procedures: "immediate exchange," in which a token earned during each trial was exchanged immediately for access…

Oxygen from Hydrogen Peroxide. A Safe Molar Volume-Molar Mass Experiment.

ERIC Educational Resources Information Center

Bedenbaugh, John H.; And Others

1988-01-01

Describes a molar volume-molar mass experiment for use in general chemistry laboratories. Gives background technical information, procedures for the titration of aqueous hydrogen peroxide with standard potassium permanganate and catalytic decomposition of hydrogen peroxide to produce oxygen, and a discussion of the results obtained in three…

21 CFR 172.133 - Dimethyl dicarbonate.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., analytical-grade Solution of 1 N diisobutylamine in chlorobenzene, distilled 1 N Acetic Acid procedure... the 1 N diisobutylamine solution by pipette and allow to stand for 5 minutes. Subsequently, titrate...). calculation ER10MR99.023 Note: For adding the diisobutylamine solution, always use the same pipette and wait...

21 CFR 172.133 - Dimethyl dicarbonate.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., analytical-grade Solution of 1 N diisobutylamine in chlorobenzene, distilled 1 N Acetic Acid procedure... the 1 N diisobutylamine solution by pipette and allow to stand for 5 minutes. Subsequently, titrate...). calculation ER10MR99.023 Note: For adding the diisobutylamine solution, always use the same pipette and wait...

Optimizing Glycemic Control Through Titration of Insulin Glargine 100 U/mL: A Review of Current and Future Approaches with a Focus on Asian Populations.

PubMed

Deerochanawong, Chaicharn; Bajpai, Shailendra; Dwipayana, I Made Pande; Hussein, Zanariah; Mabunay, Maria Aileen; Rosales, Reynaldo; Tsai, Shih-Tzer; Tsang, Man Wo

2017-12-01

Various data have demonstrated inadequate glycemic control amongst Asians with type 2 diabetes mellitus (T2DM), possibly on account of suboptimal titration of basal insulin-an issue which needs to be further examined. Here we review the available global and Asia-specific data on titration of basal insulin, with a focus on the use of insulin glargine 100 U/mL (Gla-100). We also discuss clinical evidence on the efficacy and safety of titrating Gla-100, different approaches to titration, including some of the latest technological advancements, and guidance on the titration of basal insulin from international and local Asian guidelines. The authors also provide their recommendations for the initiation and titration of basal insulin for Asian populations. Discussion of the data included in this review and in relation to the authors' clinical experience with treating T2DM in Asian patients is also included. Briefly, clinical studies demonstrate the achievement of adequate glycemic control in adults with T2DM through titration of Gla-100. However, studies investigating approaches to titration, specifically in Asian populations, are lacking and need to be conducted. Given that the management of insulin therapy is a multidisciplinary team effort involving endocrinologists, primary care physicians, nurse educators, and patients, greater resources and education targeted at these groups are needed regarding the optimal titration of basal insulin. Technological advancements in the form of mobile or web-based applications for automated dose adjustment can aid different stakeholders in optimizing the dose of basal insulin, enabling a larger number of patients in Asia to reach their target glycemic goals with improved outcomes.

The impact of Narcotrend™ EEG-guided propofol administration on the speed of recovery from pediatric procedural sedation-A randomized controlled trial.

PubMed

Weber, Frank; Walhout, Laurence C; Escher, Johanna C

2018-05-01

Propofol is often used for procedural sedation in children undergoing gastrointestinal endoscopy. Reliable assessment of the depth of hypnosis during the endoscopic procedure is challenging. Processed electroencephalography using the Narcotrend Index can help titrating propofol to a predefined sedation level. The aim of this trial was to investigate the impact of Narcotrend Index-guided titration of propofol delivery on the speed of recovery. Children, aged 12-17 years, undergoing gastrointestinal endoscopy under procedural sedation, had propofol delivered via target controlled infusion either based on Narcotrend Index guidance (group NI) or standard clinical parameters (group C). Sedation was augmented with remifentanil in both study groups. The primary endpoint of this study was to compare the speed of fulfilling discharge criteria from the operating room between study groups. Major secondary endpoints were propofol consumption, discharge readiness from the recovery room, hypnotic depth as measured by the Narcotrend Index, and adverse events. Of the 40 children included, data were obtainable from 37. The time until discharge readiness from the operating room was shorter in group NI than in group C, with a difference between medians of 4.76 minutes [95%CI 2.6 to 7.4 minutes]. The same accounts for recovery room discharge times; difference between medians 4.03 minutes [95%CI 0.81 to 7.61 minutes]. Propofol consumption and the percentage of EEG traces indicating oversedation were higher in group C than in group NI. There were no significant adverse events in either study group. Narcotrend Index guidance of propofol delivery for deep sedation in children aged 12-17 years, underdoing gastrointestinal endoscopy results in faster recovery, less drug consumption, and fewer episodes of oversedation than dosing propofol according to clinical surrogate parameters of depth of hypnosis. The results of this study provide additional evidence in favor of the safety profile of propofol/remifentanil for procedural sedation in adequately selected pediatric patients. © 2018 The Authors. Pediatric Anesthesia Published by John Wiley & Sons Ltd.

A high-throughput microtiter plate based method for the determination of peracetic acid and hydrogen peroxide.

PubMed

Putt, Karson S; Pugh, Randall B

2013-01-01

Peracetic acid is gaining usage in numerous industries who have found a myriad of uses for its antimicrobial activity. However, rapid high throughput quantitation methods for peracetic acid and hydrogen peroxide are lacking. Herein, we describe the development of a high-throughput microtiter plate based assay based upon the well known and trusted titration chemical reactions. The adaptation of these titration chemistries to rapid plate based absorbance methods for the sequential determination of hydrogen peroxide specifically and the total amount of peroxides present in solution are described. The results of these methods were compared to those of a standard titration and found to be in good agreement. Additionally, the utility of the developed method is demonstrated through the generation of degradation curves of both peracetic acid and hydrogen peroxide in a mixed solution.

A High-Throughput Microtiter Plate Based Method for the Determination of Peracetic Acid and Hydrogen Peroxide

PubMed Central

Putt, Karson S.; Pugh, Randall B.

2013-01-01

Peracetic acid is gaining usage in numerous industries who have found a myriad of uses for its antimicrobial activity. However, rapid high throughput quantitation methods for peracetic acid and hydrogen peroxide are lacking. Herein, we describe the development of a high-throughput microtiter plate based assay based upon the well known and trusted titration chemical reactions. The adaptation of these titration chemistries to rapid plate based absorbance methods for the sequential determination of hydrogen peroxide specifically and the total amount of peroxides present in solution are described. The results of these methods were compared to those of a standard titration and found to be in good agreement. Additionally, the utility of the developed method is demonstrated through the generation of degradation curves of both peracetic acid and hydrogen peroxide in a mixed solution. PMID:24260173

Evaluation of Expedient Decontamination Options with Activated Peroxide-based Liquid Sporicides

DTIC Science & Technology

2013-02-05

H2O2 (6% immediately post mixing) was verified by potassium permanganate titration (see Appendix B, DTRL MOP #3177) and then monitored throughout testing...H2O2 Concentration in AHP The concentration of H2O2 in the AHP solution was verified by analyzing with the potassium permanganate (KMnO4) titration...Concentration of H2O2 in the working decontamination solution was measured via permanganate titration in 24 samples of AHP taken from the backpack sprayer

Real-time PCR-based infectivity assay for the titration of turkey hemorrhagic enteritis virus, an adenovirus, in live vaccines.

PubMed

Mahsoub, Hassan M; Evans, Nicholas P; Beach, Nathan M; Yuan, Lijuan; Zimmerman, Kurt; Pierson, Frank W

2017-01-01

The current in vitro titration method for turkey hemorrhagic enteritis virus (THEV) is the end-point dilution assay (EPD) in suspension cell culture (CC). This assay is subjective and results in high variability among vaccine lots. In this study, a new in vitro infectivity method combining a SYBR Green I-based qPCR assay and CC was developed for titration of live hemorrhagic enteritis (HE) CC vaccines. The qPCR was used to determine the virus genome copy number (vGCN) of the internalized virus particles following inoculation of susceptible RP19 cells with 1 vaccine label dose. The measured vGCN represents the number of infectious viral particles (IVP) per 1 dose. This method was used to compare 9 vaccine lots from 3 companies in the United States. Significant lot-to-lot variations within the same company and among the various companies were found in genomic and qPCR-based infectious titer per label dose. A positive linear relationship was found between qPCR infectious titer and genomic titer. Further, considerable variations in CCID 50 titers were found among tested vaccine lots, indicating the high variability of the current titration methods. The new method provides an alternative to classical titration assays and can help reduce variation among HE vaccine products. Copyright © 2016 Elsevier B.V. All rights reserved.

Filtrates & Residues: Olfactory Titration.

ERIC Educational Resources Information Center

Wood, John T.; Eddy, Roberta M.

1996-01-01

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

Positive end-expiratory pressure at minimal respiratory elastance represents the best compromise between mechanical stress and lung aeration in oleic acid induced lung injury.

PubMed

Carvalho, Alysson Roncally S; Jandre, Frederico C; Pino, Alexandre V; Bozza, Fernando A; Salluh, Jorge; Rodrigues, Rosana; Ascoli, Fabio O; Giannella-Neto, Antonio

2007-01-01

Protective ventilatory strategies have been applied to prevent ventilator-induced lung injury in patients with acute lung injury (ALI). However, adjustment of positive end-expiratory pressure (PEEP) to avoid alveolar de-recruitment and hyperinflation remains difficult. An alternative is to set the PEEP based on minimizing respiratory system elastance (Ers) by titrating PEEP. In the present study we evaluate the distribution of lung aeration (assessed using computed tomography scanning) and the behaviour of Ers in a porcine model of ALI, during a descending PEEP titration manoeuvre with a protective low tidal volume. PEEP titration (from 26 to 0 cmH2O, with a tidal volume of 6 to 7 ml/kg) was performed, following a recruitment manoeuvre. At each PEEP, helical computed tomography scans of juxta-diaphragmatic parts of the lower lobes were obtained during end-expiratory and end-inspiratory pauses in six piglets with ALI induced by oleic acid. The distribution of the lung compartments (hyperinflated, normally aerated, poorly aerated and non-aerated areas) was determined and the Ers was estimated on a breath-by-breath basis from the equation of motion of the respiratory system using the least-squares method. Progressive reduction in PEEP from 26 cmH2O to the PEEP at which the minimum Ers was observed improved poorly aerated areas, with a proportional reduction in hyperinflated areas. Also, the distribution of normally aerated areas remained steady over this interval, with no changes in non-aerated areas. The PEEP at which minimal Ers occurred corresponded to the greatest amount of normally aerated areas, with lesser hyperinflated, and poorly and non-aerated areas. Levels of PEEP below that at which minimal Ers was observed increased poorly and non-aerated areas, with concomitant reductions in normally inflated and hyperinflated areas. The PEEP at which minimal Ers occurred, obtained by descending PEEP titration with a protective low tidal volume, corresponded to the greatest amount of normally aerated areas, with lesser collapsed and hyperinflated areas. The institution of high levels of PEEP reduced poorly aerated areas but enlarged hyperinflated ones. Reduction in PEEP consistently enhanced poorly or non-aerated areas as well as tidal re-aeration. Hence, monitoring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aeration.

Cost-effectiveness of ezetimibe coadministration in statin-treated patients not at cholesterol goal: application to Germany, Spain and Norway.

PubMed

Cook, John R; Yin, Don; Alemao, Evo; Davies, Glenn; Krobot, Karl J; Veltri, Enrico; Lipka, Leslie; Badia, Xavier

2004-01-01

Despite the growing use of statins, many hypercholesterolaemic patients fail to reach their lipid goal and remain at elevated risk of coronary heart disease (CHD). Alternative treatment strategies, such as ezetimibe coadministration and statin titration, can help patients achieve greater lipid control, and thereby lower their CHD risk. But is it cost effective to more aggressively lower cholesterol levels across a broad range of current statin users? Using a decision-analytic model based on epidemiological and clinical trials data, we project the lifetime benefit and cost of alternative lipid-lowering treatment strategies for CHD and non-CHD diabetic patients in Germany, Spain and Norway. It is projected that from 40% to 76% of these patients who have failed to reach their lipid goal with their current statin treatment will be able to reach their goal with ezetimibe coadministration; this represents a gain of up to an additional absolute 14% who will be able to reach their goal compared with a 'titrate to goal' strategy where patients are titrated in order to reach their lipid goal (up to the maximum approved dose). For CHD patients, the estimated incremental cost-effectiveness ratio for ezetimibe coadministration is under Euro 18 000 per life-year gained (Euro/LYG) and 26 000 Euro/LYG compared with strategies based on the observed titration rates and the aggressive 'titrate to goal' strategy, respectively; for non-CHD diabetic patients, these ratios are under 26 000 Euro/LYG and 48 000 Euro/LYG for ezetimibe coadministration compared with the two titration strategies. Compared with statin titration, ezetimibe coadministration is projected to be cost effective in the populations and countries studied.

Evaluation of synergistic effects of resynchronization therapy and a β-blocker up-titration strategy based on a predefined patient-management program: the RESTORE study.

PubMed

Palmisano, Pietro; Ammendola, Ernesto; D'Onofrio, Antonio; Accogli, Michele; Calò, Leonardo; Ruocco, Antonio; Rapacciuolo, Antonio; Del Giorno, Giuseppe; Bianchi, Valter; Malacrida, Maurizio; Valsecchi, Sergio; Gronda, Edoardo

2015-01-01

Prior studies have suggested that a substantial number of eligible heart failure (HF) patients fail to receive β-blocker therapy, or receive it at a suboptimal dose. The aim of this study is to assess the benefit of a predefined management program designed for β-blocker up-titration, evaluating the synergistic effect of cardiac resynchronization therapy (CRT) and β-blockers in a HF population. The Resynchronization Therapy and β-Blocker Titration (RESTORE) study is a prospective, case-control, multicenter cohort study designed to test the hypothesis that a β-blocker up-titration strategy based on a predefined management program maximizes the beneficial effect of CRT, increasing the number of patients reaching the target dose of β-blockers and improving their clinical outcome. All study patients receive an implantable defibrillator for CRT delivery in accordance with current guidelines. Enrollments started in December 2011 and are scheduled to end in December 2014. Approximately 250 consecutive patients will be prospectively enrolled in 6 Italian centers and followed up for 24 months after implantation. The primary endpoint is to demonstrate that CRT may allow titration of β-blockers until the optimal dose, or at least to the effective dose, in patients with HF. This study might provide important information about the benefit of a predefined management program for β-blocker up-titration in patients receiving CRT. Moreover, assessment of health-care utilization and the consumption of resources will allow estimating the potential utility of remote monitoring by means of an automated telemedicine system in facilitating the titration of β-blockers in comparison with a standard in-hospital approach. © 2015 Wiley Periodicals, Inc.

What is the evidence behind the evidence-base? The premature death of block-replace antithyroid drug regimens for Graves' disease.

PubMed

Razvi, Salman; Vaidya, Bijay; Perros, Petros; Pearce, Simon H S

2006-06-01

Block-replace and titration antithyroid drug regimens both give similar rates of medium- to long-term remission of hyperthyroid Graves' disease. Recent meta-analysis, however, has suggested that titration regimens may be preferable owing to a higher rate of adverse events seen in the block-replace arms of published comparative studies. This article critically re-evaluates the evidence upon which these meta-analyses were based. We suggest that there is little objective evidence that is pertinent to current clinical practice to separate block-replace from titration antithyroid drug regimens and that both remain satisfactory approaches to the medical management of hyperthyroid Graves' disease.

Development of new composite biosorbents from olive pomace wastes

NASA Astrophysics Data System (ADS)

Pagnanelli, Francesca; Viggi, Carolina Cruz; Toro, Luigi

2010-06-01

In this study olive pomace was used as a source of binding substances for the development of composite biosorbents to be used in heavy metal removal from aqueous solutions. The aim was to obtain biosorbent material with an increased concentration of binding sites. The effects of two different extraction procedures (one using only methanol and the other one hexane followed by methanol) on the binding properties of olive pomace were tested by potentiometric titrations and batch biosorption tests for copper and cadmium removal. Titration modelling evidenced that both kinds of extractions generated a solid with a reduced amount of protonatable sites. Biosorption tests were organized according to full factorial designs. Analysis of variance denoted that both kinds of extractions determined a statistically significant negative effect on metal biosorption. In the case of cadmium extractions also determined a significant decrease of selectivity with respect to olive pomace. When the acid-base and binding properties of the substances extracted were determined, they were adsorbed onto a synthetic resin (octadecylsilane) and calcium alginate beads. In this way two kinds of composite biosorbents have been obtained both having an increased concentration of binding substances with respect to native olive pomace, also working more efficiently in metal removal.

Titration effectiveness of two autoadjustable continuous positive airway pressure devices driven by different algorithms in patients with obstructive sleep apnoea.

PubMed

Damiani, Mario Francesco; Quaranta, Vitaliano Nicola; Tedeschi, Ersilia; Drigo, Riccardo; Ranieri, Teresa; Carratù, Pierluigi; Resta, Onofrio

2013-08-01

Nocturnal application of continuous positive airway pressure (CPAP) is the standard treatment for patients with obstructive sleep apnoea (OSA). Determination of the therapeutic pressure (CPAP titration) is usually performed by a technician in the sleep laboratory during attended polysomnography. One possible alternative to manual titration is automated titration. Indeed, during the last 15 years, devices have been developed that deliver autoadjustable CPAP (A-CPAP). The aim of the present study was to compare the titration effectiveness of two A-CPAP devices using different flow-based algorithms in patients with OSA. This is a randomized study; 79 subjects underwent two consecutive unattended home A-CPAP titration nights with two different devices (Autoset Resmed; Remstar Auto Respironics); during the third and the fourth night, patients underwent portable monitoring in the sleep laboratory during fixed CPAP at the A-CPAP recommended pressure. Bland Altman plots showed good agreement between the recommended median and maximal pressure levels obtained with the two devices. A significant improvement was observed in all the sleep parameters by both A-CPAP machines to a similar degree. It was observed that the two A-CPAP devices using different algorithms are equally effective in initial titration of CPAP. © 2013 The Authors. Respirology © 2013 Asian Pacific Society of Respirology.

A model for oxygen conservation associated with titration during pediatric oxygen therapy

PubMed Central

Wu, Grace; Wollen, Alec; Himley, Stephen; Austin, Glenn; Delarosa, Jaclyn; Izadnegahdar, Rasa; Ginsburg, Amy Sarah; Zehrung, Darin

2017-01-01

Background Continuous oxygen treatment is essential for managing children with hypoxemia, but access to oxygen in low-resource countries remains problematic. Given the high burden of pneumonia in these countries and the fact that flow can be gradually reduced as therapy progresses, oxygen conservation through routine titration warrants exploration. Aim To determine the amount of oxygen saved via titration during oxygen therapy for children with hypoxemic pneumonia. Methods Based on published clinical data, we developed a model of oxygen flow rates needed to manage hypoxemia, assuming recommended flow rate at start of therapy, and comparing total oxygen used with routine titration every 3 minutes or once every 24 hours versus no titration. Results Titration every 3 minutes or every 24 hours provided oxygen savings estimated at 11.7% ± 5.1% and 8.1% ± 5.1% (average ± standard error of the mean, n = 3), respectively. For every 100 patients, 44 or 30 kiloliters would be saved—equivalent to 733 or 500 hours at 1 liter per minute. Conclusions Ongoing titration can conserve oxygen, even performed once-daily. While clinical validation is necessary, these findings could provide incentive for the routine use of pulse oximeters for patient management, as well as further development of automated systems. PMID:28234903

Acid-Base Titration Curves of Soils from a Low-Centered Polygon, Barrow, Alaska, 2013

DOE Data Explorer

Jianqiu Zheng; David Graham

2017-12-05

This dataset provides pH titration data of soils from a low-centered polygon center. The soil core was collected in 2013 from a low-centered polygon center from the NGEE-Arctic Intensive Study Site 1, Barrow, Alaska.

A systematic review on the effectiveness of titratable over nontitratable mandibular advancement appliances for sleep apnea.

PubMed

Sivaramakrishnan, Gowri; Sridharan, Kannan

2017-01-01

Mandibular advancement appliances are being tested for use in patients with obstructive sleep apnea (OSA). However, the effectiveness of titration of these appliances does not have conclusive evidence. Systematic reviews help us to compile all available clinical evidence using statistical principles. Hence, the aim of this systematic review is to identify the effectiveness of titratable over nontitratable mandibular advancement appliances in patients with mild to moderate OSA. This review objective is to identify if titration of these appliances produce significant benefits over fixed appliances. Electronic databases were searched to identify eligible studies based on set inclusion criteria. Data extraction form was created and the data were extracted. The participants were mild to moderate OSA patients who received mandibular advancement appliances. Studies included a comparison between titratable and nontitratable mandibular advancement appliance. Of the five included studies, three were observational and two were a randomized trial. All these studies were conducted in adults. The outcome attributes were polysomnographic readings and apnea-hypopnea index (AHI). A significant heterogeneity was seen between the eligible studies and hence a meta-analysis could not be performed. The results from this systematic review did not show significant advantages of titratable appliances, although titratable appliances performed better from individual studies as regards to reduction in AHI and polysomnography. The reason is the lack of sufficient clinical trials on the same. More high quality randomized controlled trials comparing titratable and fixed appliances have to be initiated to get to conclusive evidence.

A field method for the determination of calcium and magnesium in limestone and dolomite

USGS Publications Warehouse

Shapiro, Leonard; Brannock, Walter Wallace

1957-01-01

The method is an adaptation of a procedure described by Betz and Noll1 in 1950. Calcium and magnesium are determined by visual titration using Versene (disodium ethylenediamine tetraacetate) with Murexide (ammonium purpurate) as the indicator for calcium and Eriochrome Black T as the indicator for magnesium.

Depression May Reduce Adherence during CPAP Titration Trial

PubMed Central

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

2014-01-01

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

Equivalence-point electromigration acid-base titration via moving neutralization boundary electrophoresis.

PubMed

Yang, Qing; Fan, Liu-Yin; Huang, Shan-Sheng; Zhang, Wei; Cao, Cheng-Xi

2011-04-01

In this paper, we developed a novel method of acid-base titration, viz. the electromigration acid-base titration (EABT), via a moving neutralization boundary (MNR). With HCl and NaOH as the model strong acid and base, respectively, we conducted the experiments on the EABT via the method of moving neutralization boundary for the first time. The experiments revealed that (i) the concentration of agarose gel, the voltage used and the content of background electrolyte (KCl) had evident influence on the boundary movement; (ii) the movement length was a function of the running time under the constant acid and base concentrations; and (iii) there was a good linearity between the length and natural logarithmic concentration of HCl under the optimized conditions, and the linearity could be used to detect the concentration of acid. The experiments further manifested that (i) the RSD values of intra-day and inter-day runs were less than 1.59 and 3.76%, respectively, indicating similar precision and stability in capillary electrophoresis or HPLC; (ii) the indicators with different pK(a) values had no obvious effect on EABT, distinguishing strong influence on the judgment of equivalence-point titration in the classic one; and (iii) the constant equivalence-point titration always existed in the EABT, rather than the classic volumetric analysis. Additionally, the EABT could be put to good use for the determination of actual acid concentrations. The experimental results achieved herein showed a new general guidance for the development of classic volumetric analysis and element (e.g. nitrogen) content analysis in protein chemistry. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Immediate effect of CPAP titration on perceived health related quality of life: a prospective observational study.

PubMed

Iacono Isidoro, Serena; Salvaggio, Adriana; Lo Bue, Anna; Romano, Salvatore; Marrone, Oreste; Insalaco, Giuseppe

2016-12-01

Perceived Health Related Quality of Life (HRQoL) is impaired in obstructive sleep apnea (OSA). This study examines changes in HRQoL aspects occurring immediately after CPAP titration. Furthermore, we analyzed variations in each gender and in patients undergoing home or laboratory-based CPAP titration pathways. Twohundredfive outpatients (151 M) (56.7 ± 10.3 years) were evaluated, before first visit and nocturnal diagnostic examination (T0), and the morning after CPAP titration (T1). Two self-reported HRQoL questionnaires were administered: Psychological General Well-Being Index (PGWBI), composed by six subscales, and 12-Item Short-Form Health Survey (SF-12), including Physical (PCS) and Mental Component Summaries (MCS). CPAP titration was performed using auto-adjusting CPAP units at patients' home or in the sleep laboratory. PGWBI scores at T1 improved compared to T0 (p < 0.0001). A similar improvement was observed in SF-12 MCS (p = 0.0011), but not in SF-12 PCS. Changes were independent from anthropometric parameters, OSA severity and excessive daytime sleepiness. Gender comparisons showed better HRQoL in males at both times. At T0, patients who received home or laboratory CPAP titration pathways did not show any differences in PGWBI and SF-12 scores. At T1, PGWBI and SF-12 MCS improved in both home and laboratory groups. This study gives evidence that first time CPAP application for titration can lead to a general increase in perceived well-being. Gender comparisons showed better perceived HRQoL with more subscales improvements in males after CPAP titration. The improvement was similar with both home and laboratory CPAP titration pathways.

Axitinib with or without dose titration for first-line metastatic renal-cell carcinoma: a randomised double-blind phase 2 trial.

PubMed

Rini, Brian I; Melichar, Bohuslav; Ueda, Takeshi; Grünwald, Viktor; Fishman, Mayer N; Arranz, José A; Bair, Angel H; Pithavala, Yazdi K; Andrews, Glen I; Pavlov, Dmitri; Kim, Sinil; Jonasch, Eric

2013-11-01

Population pharmacokinetic data suggest axitinib plasma exposure correlates with efficacy in metastatic renal-cell carcinoma. Axitinib dose titration might optimise exposure and improve outcomes. We prospectively assessed the efficacy and safety of axitinib dose titration in previously untreated patients with metastatic renal-cell carcinoma. In this randomised, double-blind, multicentre, phase 2 study, patients were enrolled from 49 hospitals and outpatient clinics in the Czech Republic, Germany, Japan, Russia, Spain, and USA. Patients with treatment-naive metastatic renal-cell carcinoma received axitinib 5 mg twice daily during a 4 week lead-in period. Those patients with blood pressure 150/90 mm Hg or lower, no grade 3 or 4 treatment-related toxic effects, no dose reductions, and no more than two antihypertensive drugs for 2 consecutive weeks were stratified by Eastern Cooperative Oncology Group performance status (0 vs 1), and then randomly assigned (1:1) to either masked titration with axitinib to total twice daily doses of 7 mg, and then 10 mg, if tolerated, or placebo titration. Patients who did not meet these criteria continued without titration. The primary objective was comparison of the proportion of patients achieving an objective response between randomised groups. Safety analyses were based on all patients who received at least one dose of axitinib. Between Sept 2, 2009, and Feb 28, 2011, we enrolled 213 patients, of whom 112 were randomly assigned to either the axitinib titration group (56 patients) or the placebo titration group (56 patients). 91 were not eligible for titration, and ten withdrew during the lead-in period. 30 patients (54%, 95% CI 40-67) in the axitinib titration group had an objective response, as did 19 patients (34%, 22-48]) in the placebo titration group (one-sided p=0·019). 54 (59%, 95% CI 49-70) of non-randomised patients achieved an objective response. Common grade 3 or worse, all-causality adverse events in treated patients were hypertension (ten [18%] of 56 in the axitinib titration group vs five [9%] of 56 in the placebo titration group vs 45 [49%] of 91 in the non-randomised group), diarrhoea (seven [13%] vs two [4%] vs eight [9%]), and decreased weight (four [7%] vs three [5%] vs six [7%]). One or more all-causality serious adverse events were reported in 15 (27%) patients in the axitinib titration group, 13 (23%) patients in the placebo titration group, and 35 (38%) non-randomised patients. The most common serious adverse events in all 213 patients were disease progression and dehydration (eight each [4%]), and diarrhoea, vomiting, pneumonia, and decreased appetite (four each [2%]). The greater proportion of patients in the axitinib titration group achieving an objective response supports the concept of individual axitinib dose titration in selected patients with metastatic renal-cell carcinoma. Axitinib shows clinical activity with a manageable safety profile in treatment-naive patients with this disease. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Colorimetric and Luminescent Dual-Modal Assay for Cu(II) Ion Detection Using an Iridium(III) Complex

PubMed Central

Ma, Dik-Lung; He, Hong-Zhang; Chan, Daniel Shiu-Hin; Wong, Chun-Yuen; Leung, Chung-Hang

2014-01-01

A novel iridium(III) complex-based chemosensor bearing the 5,6-bis(salicylideneimino)-1,10-phenanthroline ligand receptor was developed, which exhibited a highly sensitive and selective color change from colorless to yellow and a visible turn-off luminescence response upon the addition of Cu(II) ions. The interactions of this iridium(III) complex with Cu2+ ions and thirteen other cations have been investigated by UV-Vis absorption titration, emission titration, and 1H NMR titration. PMID:24927177

Balanced conscious sedation with intravenous induction and inhalational maintenance for patients requiring endoscopic and/or surgical procedures.

PubMed

Lahoud, G Y; Hopkins, P M

2007-02-01

The use of inhalation sedation with sub-anaesthetic concentrations of sevoflurane and nitrous oxide mixture is expected to reduce amounts of intravenous sedative drugs needed to produce a balanced sedation with the benefits of having reduced side-effects. Eighty-two patients requiring endoscopic and/or surgical procedures under conscious sedation and local anaesthesia were recruited for this pilot study. Conscious sedation was induced with a titrated dose of midazolam and propofol given intravenously until the clinical end-point of conscious sedation was achieved. Subsequently, during the procedure, the patient was asked to breathe sevoflurane 0.1-0.3% and a fixed ratio of 40% nitrous oxide in oxygen given through a face mask. In 78 patients (95.1%), the treatment was completed successfully. Patients were discharged back to the wards within 4-16 min (10.1) without significant side-effects. Treatment was satisfactorily accepted by 38 patients (48.7%) and considered excellent by 40 patients (51.3%). The use of titrated doses of intravenous sedative drugs for induction of conscious sedation followed by the use of low concentrations (0.1-0.3%) of sevoflurane combined with 40% nitrous oxide for maintenance of conscious sedation in patients requiring endoscopic and/or surgical procedures under local anaesthesia, has the potential advantages of reducing amounts of intravenous sedative drugs, less likelihood of problems from drug side-effects and fast recovery and discharge time. Further investigations to establish the technique are currently in progress.

Assessment of Knowledge of Self Blood Glucose Monitoring and Extent of Self Titration of Anti-Diabetic Drugs among Diabetes Mellitus Patients - A Cross Sectional, Community Based Study.

PubMed

Krishnan, V; Thirunavukkarasu, J

2016-03-01

Self blood glucose monitoring is an important context of self care in the management of diabetes mellitus. All the guidelines must be followed while performing self blood glucose monitoring and tracking of values is essential to facilitate the physician while titrating the drugs and /or doses of anti diabetes medication. Self titration by patients following self monitoring must be discouraged. To assess the knowledge and practice of self blood glucose monitoring among diabetes patients and extent of self titration of anti diabetes medicines among diabetes patients based on self blood glucose monitoring. This pilot, cross-sectional, observational study was conducted using a validated questionnaire among adult male and female diabetes patients performing self blood glucose monitoring at home. Diabetes patients with complications and juvenile diabetes patients were excluded. Out of 153 patients surveyed, only 37 (24.1%) (20 males, 17 females) patients were aware and have been following self blood glucose monitoring appropriately. About 116 (75.8%) (64 males, 52 females) of patients were devoid of adequate knowledge and did not practice self blood glucose monitoring in a proper way. Ninety eight (64.05%) accepted that they self titrate their anti diabetic medicines based on self monitoring. Self monitoring of blood glucose should be encouraged and patients should be taught importance of following correct steps and tracking of self monitoring by physician or diabetes educator.

Entropy as an indicator of cerebral perfusion in patients with increased intracranial pressure.

PubMed

Khan, James; Mariappan, Ramamani; Venkatraghavan, Lashmi

2014-07-01

Changes in electroencephalogram (EEG) patterns correlate well with changes in cerebral perfusion pressure (CPP) and hence entropy and bispectral index values may also correlate with CPP. To highlight the potential application of entropy, an EEG-based anesthetic depth monitor, on indicating cerebral perfusion in patients with increased intracranial pressure (ICP), we report two cases of emergency neurosurgical procedure in patients with raised ICP where anesthesia was titrated to entropy values and the entropy values suddenly increased after cranial decompression, reflecting the increase in CPP. Maintaining systemic blood pressure in order to maintain the CPP is the anesthetic goal while managing patients with raised ICP. EEG-based anesthetic depth monitors may hold valuable information on guiding anesthetic management in patients with decreased CPP for better neurological outcome.

The Use and Evaluation of Videodiscs in the Chemistry Laboratory.

ERIC Educational Resources Information Center

Russell, Arlene A.; And Others

1985-01-01

Describes a quantitative evaluation of an interactive videodisc program in which students measure the temperature dependence of the solubility product of lead chloride by titration of chloride with silver nitrate using a Mohr titration. Student reaction (based on responses made using the program, quiz answers, and laboratory performance) was…

Reduction in in vivo testing at the National Veterinary Services Laboratories of the United States Department of Agriculture.

PubMed

Hyde, R L

1986-01-01

Efforts are being made at the National Veterinary Services Laboratories to reduce in vivo testing of USDA licensed veterinary vaccines. A hemagglutination test for determining potency of killed parvovirus vaccine is currently being used for canine and swine adjuvanted and nonadjuvanted products; a serum neutralization inhibition test (SNIT) is being developed for potency testing of killed adjuvanted infectious bovine rhinotracheitis (IBR), bovine virus diarrhea (BVD) and parainfluenza (PI3) vaccines: and a tissue culture titration method for live avian encephalomyelitis virus vaccine is being pursued as a replacement for the old hatch-out chick embryo titration method. Difficulties in separating the antigen from oil emulsion products are preventing significant advances in developing in vitro testing procedures for poultry killed-virus vaccines.

The Plaque-Antiserum Method: an Assay of Virus Infectivity and an Experimental Model of Virus Infection

PubMed Central

De Flora, Silvio

1974-01-01

Areas of cytopathic effect can be circumscribed in cell monolayers by adding antiserum to the liquid nutrient medium after adsorption of virus. This procedure represents a simple and reliable tool for the titration of virus infectivity and provides an experimental model for studying some aspects of virus infection. Images PMID:4364462

7 CFR 58.810 - Temperature requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 3 2012-01-01 2012-01-01 false Temperature requirements. 58.810 Section 58.810... Procedures § 58.810 Temperature requirements. (a) Unless processed within 2 hours, all whey or condensed whey, except acid type whey with a titratable acidity of 0.40 percent or above, or a pH of 4.6 or below, shall...

7 CFR 58.810 - Temperature requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 3 2014-01-01 2014-01-01 false Temperature requirements. 58.810 Section 58.810... Procedures § 58.810 Temperature requirements. (a) Unless processed within 2 hours, all whey or condensed whey, except acid type whey with a titratable acidity of 0.40 percent or above, or a pH of 4.6 or below, shall...

7 CFR 58.810 - Temperature requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 3 2011-01-01 2011-01-01 false Temperature requirements. 58.810 Section 58.810... Procedures § 58.810 Temperature requirements. (a) Unless processed within 2 hours, all whey or condensed whey, except acid type whey with a titratable acidity of 0.40 percent or above, or a pH of 4.6 or below, shall...

7 CFR 58.810 - Temperature requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 3 2013-01-01 2013-01-01 false Temperature requirements. 58.810 Section 58.810... Procedures § 58.810 Temperature requirements. (a) Unless processed within 2 hours, all whey or condensed whey, except acid type whey with a titratable acidity of 0.40 percent or above, or a pH of 4.6 or below, shall...

Insulin degludec/insulin aspart once daily in Type 2 diabetes: a comparison of simple or stepwise titration algorithms (BOOST® : SIMPLE USE).

PubMed

Park, S W; Bebakar, W M W; Hernandez, P G; Macura, S; Hersløv, M L; de la Rosa, R

2017-02-01

To compare the efficacy and safety of two titration algorithms for insulin degludec/insulin aspart (IDegAsp) administered once daily with metformin in participants with insulin-naïve Type 2 diabetes mellitus. This open-label, parallel-group, 26-week, multicentre, treat-to-target trial, randomly allocated participants (1:1) to two titration arms. The Simple algorithm titrated IDegAsp twice weekly based on a single pre-breakfast self-monitored plasma glucose (SMPG) measurement. The Stepwise algorithm titrated IDegAsp once weekly based on the lowest of three consecutive pre-breakfast SMPG measurements. In both groups, IDegAsp once daily was titrated to pre-breakfast plasma glucose values of 4.0-5.0 mmol/l. Primary endpoint was change from baseline in HbA 1c (%) after 26 weeks. Change in HbA 1c at Week 26 was IDegAsp Simple -14.6 mmol/mol (-1.3%) (to 52.4 mmol/mol; 6.9%) and IDegAsp Stepwise -11.9 mmol/mol (-1.1%) (to 54.7 mmol/mol; 7.2%). The estimated between-group treatment difference was -1.97 mmol/mol [95% confidence interval (CI) -4.1, 0.2] (-0.2%, 95% CI -0.4, 0.02), confirming the non-inferiority of IDegAsp Simple to IDegAsp Stepwise (non-inferiority limit of ≤ 0.4%). Mean reduction in fasting plasma glucose and 8-point SMPG profiles were similar between groups. Rates of confirmed hypoglycaemia were lower for IDegAsp Stepwise [2.1 per patient years of exposure (PYE)] vs. IDegAsp Simple (3.3 PYE) (estimated rate ratio IDegAsp Simple /IDegAsp Stepwise 1.8; 95% CI 1.1, 2.9). Nocturnal hypoglycaemia rates were similar between groups. No severe hypoglycaemic events were reported. In participants with insulin-naïve Type 2 diabetes mellitus, the IDegAsp Simple titration algorithm improved HbA 1c levels as effectively as a Stepwise titration algorithm. Hypoglycaemia rates were lower in the Stepwise arm. © 2016 The Authors. Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.

A comparison of cationic polymerization and esterification for end-point detection in the catalytic thermometric titration of organic bases.

PubMed

J Greenhow, E; Viñas, P

1984-08-01

A systematic comparison has been made of two indicator systems for the non-aqueous catalytic thermometric titration of strong and weak organic bases. The indicator reagents, alpha-methylstyrene and mixtures of acetic anhydride and hydroxy compounds, are shown to give results (for 14 representative bases) which do not diner significantly in coefficient of variation or titration error. Calibration graphs for all the samples, in the range 0.01-0.1 meq, are linear, with correlation coefficients of 0.995 or better. Aniline, benzylamine, n-butylamine, morpholine, pyrrole, l-dopa, alpha-methyl-l-dopa, dl-alpha-alanine, dl-leucine and l-cysteine cannot be determined when acetic anhydride is present in the sample solution, but some primary and second amines can. This is explained in terms of rates of acetylation of the amino groups.

Axitinib with or without dose titration for first-line metastatic renal-cell carcinoma: a randomised double-blind phase 2 trial

PubMed Central

Rini, Brian I; Melichar, Bohuslav; Ueda, Takeshi; GrÜnwald, Viktor; Fishman, Mayer N; Arranz, José A; Bair, Angel H; Pithavala, Yazdi K; Andrews, Glen I; Pavlov, Dmitri; Kim, Sinil; Jonasch, Eric

2014-01-01

Summary Background Population pharmacokinetic data suggest axitinib plasma exposure correlates with efficacy in metastatic renal-cell carcinoma. Axitinib dose titration might optimise exposure and improve outcomes. We prospectively assessed the efficacy and safety of axitinib dose titration in previously untreated patients with metastatic renal-cell carcinoma. Methods In this randomised, double-blind, multicentre, phase 2 study, patients were enrolled from 49 hospitals and outpatient clinics in the Czech Republic, Germany, Japan, Russia, Spain, and USA. Patients with treatment-naive metastatic renal-cell carcinoma received axitinib 5 mg twice daily during a 4 week lead-in period. Those patients with blood pressure 150/90 mm Hg or lower, no grade 3 or 4 treatment-related toxic effects, no dose reductions, and no more than two antihypertensive drugs for 2 consecutive weeks were stratified by Eastern Cooperative Oncology Group performance status (0 vs 1), and then randomly assigned (1:1) to either masked titration with axitinib to total twice daily doses of 7 mg, and then 10 mg, if tolerated, or placebo titration. Patients who did not meet these criteria continued without titration. The primary objective was comparison of the proportion of patients achieving an objective response between randomised groups. Safety analyses were based on all patients who received at least one dose of axitinib. This ongoing trial is registered with ClinicalTrials.gov, number NCT00835978. Findings Between Sept 2, 2009, and Feb 28, 2011, we enrolled 213 patients, of whom 112 were randomly assigned to either the axitinib titration group (56 patients) or the placebo titration group (56 patients). 91 were not eligible for titration, and ten withdrew during the lead-in period. 30 patients (54%, 95% CI 40–67) in the axitinib titration group had an objective response, as did 19 patients (34%, 22–48]) in the placebo titration group (one-sided p=0·019). 54 (59%, 95% CI 49–70) of non-randomised patients achieved an objective response. Common grade 3 or worse, all-causality adverse events in treated patients were hypertension (ten [18%] of 56 in the axitinib titration group vs five [9%] of 56 in the placebo titration group vs 45 [49%] of 91 in the non-randomised group), diarrhoea (seven [13%] vs two [4%] vs eight [9%]), and decreased weight (four [7%] vs three [5%] vs six [7%]). One or more all-causality serious adverse events were reported in 15 (27%) patients in the axitinib titration group, 13 (23%) patients in the placebo titration group, and 35 (38%) non-randomised patients. The most common serious adverse events in all 213 patients were disease progression and dehydration (eight each [4%]), and diarrhoea, vomiting, pneumonia, and decreased appetite (four each [2%]). Interpretation The greater proportion of patients in the axitinib titration group achieving an objective response supports the concept of individual axitinib dose titration in selected patients with metastatic renal-cell carcinoma. Axitinib shows clinical activity with a manageable safety profile in treatment-naive patients with this disease. Funding Pfizer Inc. PMID:24140184

Effects of different crystal faces on the surface charge of colloidal goethite (α-FeOOH) particles: an experimental and modeling study

NASA Astrophysics Data System (ADS)

Gaboriaud, Fabien; Ehrhardt, Jean-Jacques

2003-03-01

The surface charge of colloidal particles is usually determined by potentiometric titration. These acid-base titrations make it possible to measure the pH of point-of-zero charge (pzc) for oxide minerals. This macroscopic property is the most important parameter used in surface complexation modeling to reproduce experimental data. The pzc values of goethite reported in the literature vary between 7.0 and 9.5. Carbonate adsorption and/or surface morphology are thought to account for this wide range. We demonstrate a procedure for the removal of the carbonate ions that initially adsorb on goethite and strongly affect the titration curves and pzc determination. We also investigated the crystal-face-specific reactivity of two morphologically different goethites. The z-profiles obtained from atomic force microscopy (AFM) images showed that the goethite with the smallest specific surface area ( S = 49 m 2/g, denoted G49) exhibits 70% of the (001) face, whereas this value is only 30% for the goethite with largest specific surface area ( S = 95 m 2/g, denoted G95). This morphologic difference results in slightly different pzc values: 9.0 for G49 goethite and 9.1 for G95 geothite. These experimental pzc values have been correlated with multisite complexation calculations using both the full-site and the 1-pK approaches. We used the full-site approach to consider all of the configurations of hydrogen bond interactions with surface site. The resulting mean charges gave estimated pzc values of 8.9 and 9.2 for the (001) and (101) faces, respectively. Considering these theoretical pzc values for individual faces and the face distributions obtained from AFM analysis, the calculated pzc values are in full agreement with the experimental pzc values. However, this morphologic difference is more expressed in surface charge values than in the pzc values. Indeed, the surface charge of G49 goethite is much higher than that of G95 goethite, and the 1-pK calculations make it possible to fit the titration data satisfactorily.

Titration and HPLC Characterization of Kombucha Fermentation: A Laboratory Experiment in Food Analysis

ERIC Educational Resources Information Center

Miranda, Breanna; Lawton, Nicole M.; Tachibana, Sean R.; Swartz, Natasja A.; Hall, W. Paige

2016-01-01

Quantification of the many constituents that make up our food, whether they are desirable (vitamins, antioxidants, nutrients) or undesirable (pesticides, toxins), is one of the most practical applications of chemistry. In this study, kombucha, a popular fermented tea beverage, was analyzed using acid-base titration and high-performance liquid…

Calculating Equilibrium Constants in the SnCl2-H2O-NaOH System According to Potentiometric Titration Data

NASA Astrophysics Data System (ADS)

Maskaeva, L. N.; Fedorova, E. A.; Yusupov, R. A.; Markov, V. F.

2018-05-01

The potentiometric titration of tin chloride SnCl2 is performed in the concentration range of 0.00009-1.1 mol/L with a solution of sodium hydroxide NaOH. According to potentiometric titration data based on modeling equilibria in the SnCl2-H2O-NaOH system, basic equations are generated for the main processes, and instability constants are calculated for the resulting hydroxo complexes and equilibrium constants of low-soluble tin(II) compounds. The data will be of interest for specialists in the field of theory of solutions.

A comparison between simplified and intensive dose-titration algorithms using AIR inhaled insulin for insulin-naive patients with type 2 diabetes in a randomized noninferiority trial.

PubMed

Mathieu, C; Cuddihy, R; Arakaki, R F; Belin, R M; Planquois, J-M; Lyons, J N; Heilmann, C R

2009-09-01

Insulin initiation and optimization is a challenge for patients with type 2 diabetes. Our objective was to determine whether safety and efficacy of AIR inhaled insulin (Eli Lilly and Co., Indianapolis, IN) (AIR is a registered trademark of Alkermes, Inc., Cambridge, MA) using a simplified regimen was noninferior to an intensive regimen. This was an open-label, randomized study in insulin-naive adults not optimally controlled by oral antihyperglycemic medications. Simplified titration included a 6 U per meal AIR insulin starting dose. Individual doses were adjusted at mealtime in 2-U increments from the previous day's four-point self-monitored blood glucose (SMBG) (total < or =6 U). Starting Air insulin doses for intensive titration were based on fasting blood glucose, gender, height, and weight. Patients conducted four-point SMBG daily for the study duration. Insulin doses were titrated based on the previous 3 days' mean SMBG (total < or =8 U). End point hemoglobin A1C (A1C) was 7.07 +/- 0.09% and 6.87 +/- 0.09% for simplified (n = 178) and intensive (n = 180) algorithms, respectively. Noninferiority between algorithms was not established. The fasting blood glucose (least squares mean +/- standard error) values for the simplified (137.27 +/- 3.42 mg/dL) and intensive (133.13 +/- 3.42 mg/dL) algorithms were comparable. Safety profiles were comparable. The hypoglycemic rate at 4, 8, 12, and 24 weeks was higher in patients receiving intensive titration (all P < .0001). The nocturnal hypoglycemic rate for patients receiving intensive titration was higher than for those receiving simplified titration at 8 (P < 0.015) and 12 weeks (P < 0.001). Noninferiority between the algorithms, as measured by A1C, was not demonstrated. This finding re-emphasizes the difficulty of identifying optimal, simplified insulin regimens for patients.

Digital movie-based on automatic titrations.

PubMed

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

2016-01-15

This study proposes the use of digital movies (DMs) in a flow-batch analyzer (FBA) to perform automatic, fast and accurate titrations. The term used for this process is "Digital movie-based on automatic titrations" (DMB-AT). A webcam records the DM during the addition of the titrant to the mixing chamber (MC). While the DM is recorded, it is decompiled into frames ordered sequentially at a constant rate of 26 frames per second (FPS). The first frame is used as a reference to define the region of interest (ROI) of 28×13pixels and the R, G and B values, which are used to calculate the Hue (H) values for each frame. The Pearson's correlation coefficient (r) is calculated between the H values of the initial frame and each subsequent frame. The titration curves are plotted in real time using the r values and the opening time of the titrant valve. The end point is estimated by the second derivative method. A software written in C language manages all analytical steps and data treatment in real time. The feasibility of the method was attested by application in acid/base test samples and edible oils. Results were compared with classical titration and did not present statistically significant differences when the paired t-test at the 95% confidence level was applied. The proposed method is able to process about 117-128 samples per hour for the test and edible oil samples, respectively, and its precision was confirmed by overall relative standard deviation (RSD) values, always less than 1.0%. Copyright © 2015 Elsevier B.V. All rights reserved.

Improving medication titration in heart failure by embedding a structured medication titration plan.

PubMed

Hickey, Annabel; Suna, Jessica; Marquart, Louise; Denaro, Charles; Javorsky, George; Munns, Andrew; Mudge, Alison; Atherton, John J

2016-12-01

To improve up-titration of medications to target dose in heart failure patients by improving communication from hospital to primary care. This quality improvement project was undertaken within three heart failure disease management (HFDM) services in Queensland, Australia. A structured medication plan was collaboratively designed and implemented in an iterative manner, using methods including awareness raising and education, audit and feedback, integration into existing work practice, and incentive payments. Evaluation was undertaken using sequential audits, and included process measures (use of the titration plan, assignment of responsibility) and outcome measures (proportion of patients achieving target dose) in HFDM service patients with reduced left ventricular ejection fraction. Comparison of the three patient cohorts (pre-intervention cohort A n=96, intervention cohort B n=95, intervention cohort C n=89) showed increase use of the titration plan, a shift to greater primary care responsibility for titration, and an increase in the proportion of patients achieving target doses of angiotensin converting enzyme inhibitors/angiotensin receptor blockers (ACEI/ARB) (A 37% vs B 48% vs C 55%, p=0.051) and beta-blockers (A 38% vs B 33% vs C 51%, p=0.045). Combining all three cohorts, patients not on target doses when discharged from hospital were more likely to achieve target doses of ACEI/ARB (p<0.0001) and beta blockers (p<0.0001) within six months if they received a medication titration plan. A medication titration plan was successfully implemented in three HFDM services and improved transitional communication and achievement of target doses of evidence-based therapies within six months of hospital discharge. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Dose Titration of Pregabalin in Patients with Painful Diabetic Peripheral Neuropathy: Simulation Based on Observational Study Patients Enriched with Data from Randomized Studies.

PubMed

Alexander, Joe; Edwards, Roger A; Manca, Luigi; Grugni, Roberto; Bonfanti, Gianluca; Emir, Birol; Whalen, Edward; Watt, Stephen; Parsons, Bruce

2018-03-01

Achieving a therapeutic response to pregabalin in patients with painful diabetic peripheral neuropathy (pDPN) requires adequate upward dose titration. Our goal was to identify relationships between titration and response to pregabalin in patients with pDPN. Data were integrated from nine randomized, placebo-controlled clinical trials as well as one 6-week open-label observational study conducted by 5808 physicians (2642 patients with pDPN) in standard outpatient settings in Germany. These studies evaluated pregabalin for treatment of pDPN. Using these data, we examined "what if" scenarios using a microsimulation platform that integrates data from randomized and observational sources as well as autoregressive-moving-average with exogenous inputs models that predict pain outcomes, taking into account weekly changes in pain, sleep interference, dose, and other patient characteristics that were unchanging. Final pain levels were significantly different depending on dose changes (P < 0.0001), with greater proportions improving with upward titration regardless of baseline pain severity. Altogether, 78.5% of patients with pDPN had 0-1 dose change, and 15.2% had ≥ 2 dose changes. Simulation demonstrated that the 4.8% of inadequately titrated patients who did not improve/very much improve their pain levels would have benefited from ≥ 2 dose changes. Patient satisfaction with tolerability (range 90.3-96.2%) was similar, regardless of baseline pain severity, number of titrations, or extent of improvement, suggesting that tolerability did not influence treatment response patterns. Upward dose titration reduced pain in patients with pDPN who actually received it. Simulation also predicted pain reduction in an inadequately titrated nonresponder subgroup of patients had they actually received adequate titration. The decision not to uptitrate must have been driven by factors other than tolerability. Pfizer, Inc.

Efficient analysis of stochastic gene dynamics in the non-adiabatic regime using piecewise deterministic Markov processes

PubMed Central

2018-01-01

Single-cell experiments show that gene expression is stochastic and bursty, a feature that can emerge from slow switching between promoter states with different activities. In addition to slow chromatin and/or DNA looping dynamics, one source of long-lived promoter states is the slow binding and unbinding kinetics of transcription factors to promoters, i.e. the non-adiabatic binding regime. Here, we introduce a simple analytical framework, known as a piecewise deterministic Markov process (PDMP), that accurately describes the stochastic dynamics of gene expression in the non-adiabatic regime. We illustrate the utility of the PDMP on a non-trivial dynamical system by analysing the properties of a titration-based oscillator in the non-adiabatic limit. We first show how to transform the underlying chemical master equation into a PDMP where the slow transitions between promoter states are stochastic, but whose rates depend upon the faster deterministic dynamics of the transcription factors regulated by these promoters. We show that the PDMP accurately describes the observed periods of stochastic cycles in activator and repressor-based titration oscillators. We then generalize our PDMP analysis to more complicated versions of titration-based oscillators to explain how multiple binding sites lengthen the period and improve coherence. Last, we show how noise-induced oscillation previously observed in a titration-based oscillator arises from non-adiabatic and discrete binding events at the promoter site. PMID:29386401

Potentiometric Titrations for Measuring the Capacitance of Colloidal Photodoped ZnO Nanocrystals.

PubMed

Brozek, Carl K; Hartstein, Kimberly H; Gamelin, Daniel R

2016-08-24

Colloidal semiconductor nanocrystals offer a unique opportunity to bridge molecular and bulk semiconductor redox phenomena. Here, potentiometric titration is demonstrated as a method for quantifying the Fermi levels and charging potentials of free-standing colloidal n-type ZnO nanocrystals possessing between 0 and 20 conduction-band electrons per nanocrystal, corresponding to carrier densities between 0 and 1.2 × 10(20) cm(-3). Potentiometric titration of colloidal semiconductor nanocrystals has not been described previously, and little precedent exists for analogous potentiometric titration of any soluble reductants involving so many electrons. Linear changes in Fermi level vs charge-carrier density are observed for each ensemble of nanocrystals, with slopes that depend on the nanocrystal size. Analysis indicates that the ensemble nanocrystal capacitance is governed by classical surface electrical double layers, showing no evidence of quantum contributions. Systematic shifts in the Fermi level are also observed with specific changes in the identity of the charge-compensating countercation. As a simple and contactless alternative to more common thin-film-based voltammetric techniques, potentiometric titration offers a powerful new approach for quantifying the redox properties of colloidal semiconductor nanocrystals.

The influence of graded degrees of chronic hypercapnia on the acute carbon dioxide titration curve

PubMed Central

Goldstein, Marc B.; Gennari, F. John; Schwartz, William B.

1971-01-01

Studies were carried out to determine the influence of the chronic level of arterial carbon dioxide tension upon the buffering response to acute changes in arterial carbon dioxide tension. After chronic adaptation to six levels of arterial CO2 tension, ranging between 35 and 110 mm Hg, unanesthetized dogs underwent acute whole body CO2 titrations. In each instance a linear relationship was observed between the plasma hydrogen ion concentration and the arterial carbon dioxide tension. Because of this linear relationship, it has been convenient to compare the acute buffering responses among dogs in terms of the slope, dH+/dPaco2. With increasing chronic hypercapnia there was a decrease in this slope, i.e. an improvement in buffer capacity, which is expressed by the equation dH+/dPaco2=-0.005 (Paco2)chronic + 0.95. In effect, the ability to defend pH during acute titration virtually doubled as chronic Paco2 increased from 35 to 110 mm Hg. The change in slope, dH+/dPaco2, was the consequence of the following two factors: the rise in plasma bicarbonate concentration which occurs with chronic hypercapnia of increasing severity, and the greater change in bicarbonate concentration which occurred during the acute CO2 titration in the animals with more severe chronic hypercapnia. These findings demonstrate the importance of the acid-base status before acute titration in determining the character of the carbon dioxide titration curve. They also suggest that a quantitative definition of the interplay between acute and chronic hypercapnia in man should assist in the rational analysis of acid-base disorders in chronic pulmonary insufficiency. PMID:5543876

Neural control of ventilation prevents both over-distension and de-recruitment of experimentally injured lungs.

PubMed

Brander, Lukas; Moerer, Onnen; Hedenstierna, Göran; Beck, Jennifer; Takala, Jukka; Slutsky, Arthur S; Sinderby, Christer

2017-03-01

Endogenous pulmonary reflexes may protect the lungs during mechanical ventilation. We aimed to assess integration of continuous neurally adjusted ventilatory assist (cNAVA), delivering assist in proportion to diaphragm's electrical activity during inspiration and expiration, and Hering-Breuer inflation and deflation reflexes on lung recruitment, distension, and aeration before and after acute lung injury (ALI). In 7 anesthetised rabbits with bilateral pneumothoraces, we identified adequate cNAVA level (cNAVA AL ) at the plateau in peak ventilator pressure during titration procedures before (healthy lungs with endotracheal tube, [HL ETT ]) and after ALI (endotracheal tube [ALI ETT ] and during non-invasive ventilation [ALI NIV ]). Following titration, cNAVA AL was maintained for 5min. In 2 rabbits, procedures were repeated after vagotomy (ALI ETT+VAG ). In 3 rabbits delivery of assist was temporarily modulated to provide assist on inspiration only. Computed tomography was performed before intubation, before ALI, during cNAVA titration, and after maintenance at cNAVA AL . During ALI ETT and ALI NIV , normally aerated lung-regions doubled and poorly aerated lung-regions decreased to less than a third (p<0.05) compared to HL ETT ; no over-distension was observed. Tidal volumes were<5ml/kg throughout. Removing assist during expiration resulted in lung de-recruitment during ALI ETT , but not during ALI NIV . During ALI ETT+VAG the expiratory portion of EAdi disappeared, resulting in cyclic lung collapse and recruitment. When using cNAVA in ALI, vagally mediated reflexes regulated lung recruitment preventing both lung over-distension and atelectasis. During non-invasive cNAVA the upper airway muscles play a role in preventing atelectasis. Future studies should be performed to compare these findings with conventional lung-protective approaches. Copyright © 2016 Elsevier B.V. All rights reserved.

Understanding the bias between moisture content by oven drying and water content by Karl Fischer titration at moisture equilibrium

USDA-ARS?s Scientific Manuscript database

Multiple causes of the difference between equilibrium moisture and water content have been found. The errors or biases were traced to the oven drying procedure to determine moisture content. The present paper explains the nature of the biases in oven drying and how it is possible to suppress one ...

A SIMPLE AND RAPID METHOD FOR THE SIMULTANEOUS DETERMINATION OF CALCIUM AND MAGNESIUM FROM THE SAME SAMPLE OF BLOOD SERUM

PubMed Central

Kovács, G. S.; Tárnoky, K. E.

1960-01-01

A simple and rapid procedure has been developed for the complexometric titration of serum calcium and magnesium using “plasmocorinth B” as indicator. Both determinations can be carried out from the same 0.5 ml. sample. The method is in good agreement with the established calcium and magnesium methods. PMID:14411396

Chemical Characterization and Toxicologic Evaluation of Airborne Mixtures

DTIC Science & Technology

1981-04-01

in the chamber air (",50% relative humidity) that phosphoric acid would be the principal component of the...triphosphoric, and tetrametaphosphoric acids were present; trimeta- phosphoric and tetrapolyphosporic acids may also have been present in trace amounts. The...triphosphoric acid , diphosphoric acid , and phosphoric acid are all strong acids that, with strong bases, can be titrated in water. Titration

Reference test methods for total water in lint cotton by Karl Fischer Titration and low temperature distillation

USDA-ARS?s Scientific Manuscript database

In a study of comparability of total water contents (%) of conditioned cottons by Karl Fischer Titration (KFT) and Low Temperature Distillation (LTD) reference methods, we demonstrated a match of averaged results based on a large number of replications and weighing the test specimens at the same tim...

Using Conductivity Measurements to Determine the Identities and Concentrations of Unknown Acids: An Inquiry Laboratory Experiment

ERIC Educational Resources Information Center

Smith, K. Christopher; Garza, Ariana

2015-01-01

This paper describes a student designed experiment using titrations involving conductivity measurements to identify unknown acids as being either HCl or H[subscript 2]SO[subscript 4], and to determine the concentrations of the acids, thereby improving the utility of standard acid-base titrations. Using an inquiry context, students gain experience…

Thermometric studies on the Fe(III)-EDTA chelate.

PubMed

Dot, K

1978-02-01

A DeltaH of -11.5 +/- 0.5 kJ/mole has been determined for the formation of the Fe(III)-EDTA chelate at 25.0 degrees and mu = 0.1(= [HClO(4)] + [NaClO(4)]) by a direct thermometric titration procedure. The entropy change, DeltaS, has been calculated to be 440 J.mole(-1) .deg(-1) by combining the result of the heat measurements with the free energy change obtained from the stability constant previously determined. A relationship between the DeltaS values and the standard partial molal entropies of the tervalent metal ions is discussed. In addition, conditions for the thermometric titration of Fe(III) with NA(4)EDTA at room temperature have been investigated. Iron(III) can be determined in the presence of fairly large amounts of phosphate, Cr(III), Mn(II) and Al(III).

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

PubMed

Karita, Shingo; Kaneta, Takashi

2014-12-16

Rapid and simple acid-base titration was accomplished using a novel microfluidic paper-based analytical device (μPAD). The μPAD 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 μPAD 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 μPADs 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 μPAD was applicable to the titrations of nitric acid, sulfuric acid, acetic acid, and ammonia solutions. The μPADs 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 μPAD, and the results agreed well with those obtained by classic acid-base titration.

An on-line potentiometric sequential injection titration process analyser for the determination of acetic acid.

PubMed

van Staden, J F; Mashamba, Mulalo G; Stefan, Raluca I

2002-09-01

An on-line potentiometric sequential injection titration process analyser for the determination of acetic acid is proposed. A solution of 0.1 mol L(-1) sodium chloride is used as carrier. Titration is achieved by aspirating acetic acid samples between two strong base-zone volumes into a holding coil and by channelling the stack of well-defined zones with flow reversal through a reaction coil to a potentiometric sensor where the peak widths were measured. A linear relationship between peak width and logarithm of the acid concentration was obtained in the range 1-9 g/100 mL. Vinegar samples were analysed without any sample pre-treatment. The method has a relative standard deviation of 0.4% with a sample frequency of 28 samples per hour. The results revealed good agreement between the proposed sequential injection and an automated batch titration method.

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

PubMed

Jonnalagadda, Sreekanth B; Gengan, Prabhashini

2010-01-01

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

[The water content reference material of water saturated octanol].

PubMed

Wang, Haifeng; Ma, Kang; Zhang, Wei; Li, Zhanyuan

2011-03-01

The national standards of biofuels specify the technique specification and analytical methods. A water content certified reference material based on the water saturated octanol was developed in order to satisfy the needs of the instrument calibration and the methods validation, assure the accuracy and consistency of results in water content measurements of biofuels. Three analytical methods based on different theories were employed to certify the water content of the reference material, including Karl Fischer coulometric titration, Karl Fischer volumetric titration and quantitative nuclear magnetic resonance. The consistency of coulometric and volumetric titration was achieved through the improvement of methods. The accuracy of the certified result was improved by the introduction of the new method of quantitative nuclear magnetic resonance. Finally, the certified value of reference material is 4.76% with an expanded uncertainty of 0.09%.

Graphical evaluation of complexometric titration curves.

PubMed

Guinon, J L

1985-04-01

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

Prediction of fermentation index of cocoa beans (Theobroma cacao L.) based on color measurement and artificial neural networks.

PubMed

León-Roque, Noemí; Abderrahim, Mohamed; Nuñez-Alejos, Luis; Arribas, Silvia M; Condezo-Hoyos, Luis

2016-12-01

Several procedures are currently used to assess fermentation index (FI) of cocoa beans (Theobroma cacao L.) for quality control. However, all of them present several drawbacks. The aim of the present work was to develop and validate a simple image based quantitative procedure, using color measurement and artificial neural network (ANNs). ANN models based on color measurements were tested to predict fermentation index (FI) of fermented cocoa beans. The RGB values were measured from surface and center region of fermented beans in images obtained by camera and desktop scanner. The FI was defined as the ratio of total free amino acids in fermented versus non-fermented samples. The ANN model that included RGB color measurement of fermented cocoa surface and R/G ratio in cocoa bean of alkaline extracts was able to predict FI with no statistical difference compared with the experimental values. Performance of the ANN model was evaluated by the coefficient of determination, Bland-Altman plot and Passing-Bablok regression analyses. Moreover, in fermented beans, total sugar content and titratable acidity showed a similar pattern to the total free amino acid predicted through the color based ANN model. The results of the present work demonstrate that the proposed ANN model can be adopted as a low-cost and in situ procedure to predict FI in fermented cocoa beans through apps developed for mobile device. Copyright © 2016 Elsevier B.V. All rights reserved.

The Sound and Feel of Titrations: A Smartphone Aid for Color-Blind and Visually Impaired Students

ERIC Educational Resources Information Center

Bandyopadhyay, Subhajit; Rathod, Balraj B.

2017-01-01

An Android-based application has been developed to provide color-blind and visually impaired students a multisensory perception of color change observed in a titration. The application records and converts the color information into beep sounds and vibration pulses, which are generated by the smartphone. It uses a range threshold of hue and…

Thermodynamic analysis of Bacillus subtilis endospore protonation using isothermal titration calorimetry

NASA Astrophysics Data System (ADS)

Harrold, Zoë R.; Gorman-Lewis, Drew

2013-05-01

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.

Zinc sorption to three gram-negative bacteria: combined titration, modeling, and EXAFS study.

PubMed

Guiné, V; Spadini, L; Sarret, G; Muris, M; Delolme, C; Gaudet, J P; Martins, J M F

2006-03-15

The acid-base and Zn sorption properties of three bacteria, Cupriavidus metallidurans CH34, Pseudomonas putida ATCC12633, and Escherichia coli K12DH5alpha, were investigated through an original combination of extended X-ray absorption fine structure (EXAFS) spectroscopy and equilibrium titration studies. Acid-base titration curves of the three strains were fitted with a model accounting for three conceptual reactive sites: an acidic (carboxyl and/or phosphodiester), a neutral (phosphomonoester), and a basic (amine and/or hydroxyl) group. Calculated proton and Zn equilibrium constants and site densities compare with literature data. The nature of Zn binding sites was studied by EXAFS spectroscopy. Phosphoester, carboxyl, and unexpectedly sulfhydryl ligands were identified. Their proportions depended on Zn loading and bacterial strain and were consistent with the titration results. These findings were compared to the structure and site density of the major cell wall components. It appeared that the cumulated theoretical site density of these structures (<2 Zn nm(-2)) was much lower than the total site density of the investigated strains (16-56 Zn nm(-2)). These results suggest a dominant role of extracellular polymeric substances in Zn retention processes, although Zn binding to inner cell components cannot be excluded.

Modeling the acid-base surface chemistry of montmorillonite.

PubMed

Bourg, Ian C; Sposito, Garrison; Bourg, Alain C M

2007-08-15

Proton uptake on montmorillonite edge surfaces can control pore water pH, solute adsorption, dissolution kinetics and clay colloid behavior in engineered clay barriers and natural weathering environments. Knowledge of proton uptake reactions, however, is currently limited by strong discrepancies between reported montmorillonite titration data sets and by conflicting estimates of edge structure, reactivity and electrostatics. In the present study, we show that the apparent discrepancy between titration data sets results in large part from the widespread use of an erroneous assumption of zero specific net proton surface charge at the onset of titration. Using a novel simulation scheme involving a surface chemistry model to simulate both pretreatment and titration, we find that montmorillonite edge surface chemistry models that account for the "spillover" of electrostatic potential from basal onto edge surfaces and for the stabilization of deprotonated Al-Si bridging sites through bond-length relaxation at the edge surface can reproduce key features of the best available experimental titration data (the influence of pretreatment conditions on experimental results, the absence of a point of zero salt effect, buffer capacity in the acidic pH range). However, no combination of current models of edge surface structure, reactivity and electrostatics can quantitatively predict, without fitted parameters, the experimental titration data over the entire range of pH (4.5 to 9) and ionic strength (0.001 to 0.5 mol dm(-3)) covered by available data.

Determination of the Effect of Various Modes of Cooking on the Vitamin C Content of a Common Food, Green Pepper: An Introductory Biochemistry Experiment.

ERIC Educational Resources Information Center

Johnson, Eric R.

1988-01-01

Describes a laboratory experiment that measures the amount of ascorbic acid destroyed by food preparation methods (boiling and steaming). Points out that aqueous extracts of cooked green pepper samples can be analyzed for ascorbic acid by a relatively simple redox titration. Lists experimental procedure for four methods of preparation. (MVL)

DETERMINING SERUM BICARBONATE—A Simple Syringe Titrator and Colorimeter

PubMed Central

Boone, Charles W.; Field, John B.

1953-01-01

The use of a tuberculin syringe as a burette has made possible an easy bedside technique for the determination of serum bicarbonate. By combining it with the use of a simple colorimeter, a relatively untrained person can do numerous bicarbonate determinations with a high degree of accuracy. The same technique also lends itself to other colorimetric clinical procedures such as determination of gastric acidity. PMID:13106724

Determining serum bicarbonate; a simple syringe titrator and colorimeter.

PubMed

BOONE, C W; FIELD, J B

1953-12-01

The use of a tuberculin syringe as a burette has made possible an easy bedside technique for the determination of serum bicarbonate. By combining it with the use of a simple colorimeter, a relatively untrained person can do numerous bicarbonate determinations with a high degree of accuracy. The same technique also lends itself to other colorimetric clinical procedures such as determination of gastric acidity.

Efficient analysis of stochastic gene dynamics in the non-adiabatic regime using piecewise deterministic Markov processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Yen Ting; Buchler, Nicolas E.

Single-cell experiments show that gene expression is stochastic and bursty, a feature that can emerge from slow switching between promoter states with different activities. In addition to slow chromatin and/or DNA looping dynamics, one source of long-lived promoter states is the slow binding and unbinding kinetics of transcription factors to promoters, i.e. the non-adiabatic binding regime. Here, we introduce a simple analytical framework, known as a piecewise deterministic Markov process (PDMP), that accurately describes the stochastic dynamics of gene expression in the non-adiabatic regime. We illustrate the utility of the PDMP on a non-trivial dynamical system by analysing the propertiesmore » of a titration-based oscillator in the non-adiabatic limit. We first show how to transform the underlying chemical master equation into a PDMP where the slow transitions between promoter states are stochastic, but whose rates depend upon the faster deterministic dynamics of the transcription factors regulated by these promoters. We show that the PDMP accurately describes the observed periods of stochastic cycles in activator and repressor-based titration oscillators. We then generalize our PDMP analysis to more complicated versions of titration-based oscillators to explain how multiple binding sites lengthen the period and improve coherence. Finally, we show how noise-induced oscillation previously observed in a titration-based oscillator arises from non-adiabatic and discrete binding events at the promoter site.« less

Determination of concentration and molar absorptivity of hypochlorous acid and hypobromous acid species by hydrogen peroxide titration

NASA Astrophysics Data System (ADS)

Uehara, H.; Arakaki, T.

2017-12-01

Hypochlorous acid and hypobromous acid (abbreviated as "HypoX acids") are the main ingredients of bleaching and bactericides. The HypoX acids change their chemical forms depending on environmental factors such as pH and various chemical reactions. For example, it has been reported that hypobromite ion in water changes to carcinogenic bromate by photochemical reaction with ultraviolet light. In this study, concentrations of HypoX acids were determined by UV-VIS absorbance measurement utilizing the fact that HypoX acids react with hydrogen peroxide and do not co-exist in the solution. The method for determining the concentration by titration with hydrogen peroxide can be carried out simpler and more efficiently than the DPD method or the current titration method generally used for chlorine concentration measurement. Molar absorptivity between 250 - 500 nm of HypoX acids, including their conjugate base species, was determined by solving theoretical acid-base formula including molar fraction of each chemical species at various pHs. Molar absorptivity of OCl- and OBr- between 250 - 500 nm was determined based on the concentrations obtained from titration with hydrogen peroxide and absorbance at pH > 10, where OCl- and OBr- dominate. Furthermore, the HypoX acids solutions were irradiated with a solar simulator, and the photolysis rate constants were obtained. Based on those values, the half-lives were calculated and the behavior of HypoX acids in the environment was elucidated.

Efficient analysis of stochastic gene dynamics in the non-adiabatic regime using piecewise deterministic Markov processes

DOE PAGES

Lin, Yen Ting; Buchler, Nicolas E.

2018-01-31

Single-cell experiments show that gene expression is stochastic and bursty, a feature that can emerge from slow switching between promoter states with different activities. In addition to slow chromatin and/or DNA looping dynamics, one source of long-lived promoter states is the slow binding and unbinding kinetics of transcription factors to promoters, i.e. the non-adiabatic binding regime. Here, we introduce a simple analytical framework, known as a piecewise deterministic Markov process (PDMP), that accurately describes the stochastic dynamics of gene expression in the non-adiabatic regime. We illustrate the utility of the PDMP on a non-trivial dynamical system by analysing the propertiesmore » of a titration-based oscillator in the non-adiabatic limit. We first show how to transform the underlying chemical master equation into a PDMP where the slow transitions between promoter states are stochastic, but whose rates depend upon the faster deterministic dynamics of the transcription factors regulated by these promoters. We show that the PDMP accurately describes the observed periods of stochastic cycles in activator and repressor-based titration oscillators. We then generalize our PDMP analysis to more complicated versions of titration-based oscillators to explain how multiple binding sites lengthen the period and improve coherence. Finally, we show how noise-induced oscillation previously observed in a titration-based oscillator arises from non-adiabatic and discrete binding events at the promoter site.« less

Microscale Titration in Schools Titration Competition.

ERIC Educational Resources Information Center

Clark, Michael J.

1998-01-01

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

Antioxidative Categorization of Twenty Amino Acids Based on Experimental Evaluation.

PubMed

Xu, Naijin; Chen, Guanqun; Liu, Hui

2017-11-27

In view of the great importance bestowed on amino acids as antioxidants in oxidation resistance, we attempted two common redox titration methods in this report, including micro-potassium permanganate titration and iodometric titration, to measure the antioxidative capacity of 20 amino acids, which are the construction units of proteins in living organisms. Based on the relative intensities of the antioxidative capacity, we further conducted a quantitative comparison and found out that the product of experimental values obtained from the two methods was proven to be a better indicator for evaluating the relative antioxidative capacity of amino acids. The experimental results were largely in accordance with structural analysis made on amino acids. On the whole, the 20 amino acids concerned could be divided into two categories according to their antioxidative capacity. Seven amino acids, including tryptophan, methionine, histidine, lysine, cysteine, arginine and tyrosine, were greater in total antioxidative capacity compared with the other 13 amino acids.

Complications associated with intravenous midazolam and fentanyl sedation in patients undergoing minor oral surgery

PubMed Central

2017-01-01

Background Anxiety control remains an important concern in dental practice. We evaluated the incidence, nature, and sequelae of complications during and after minor oral surgeries performed under intravenous midazolam and fentanyl sedation using the titration technique. Methods The medical records of patients who had undergone minor oral surgeries under moderate intravenous midazolam and fentanyl sedation at our institution between January 1, 2015 and December 31, 2015 were retrospectively evaluated. Age, sex, body mass index, medical history, American Society of Anesthesiologists (ASA) classification, indications for sedation, amount of sedative used, surgical duration, and recovery time were evaluated for all patients. Results In total, 107 patients aged 9–84 years were included. ASA class I and class II were observed for 56.1% and 43.9% patients, respectively. Complications associated with sedation occurred in 11 (10.2%) patients. There were no serious adverse events. Oxygen saturation reached 95% during the procedure in six patients; this was successfully managed by stimulating the patients to take a deep breath. Two patients exhibited deep sedation and one exhibited paradoxical excitement. After the procedure, one patient experienced nausea without vomiting and one exhibited a prolonged recovery time. The surgical procedures were completed in all patients. Obesity was found to be significantly associated with sedation-related complications. Conclusions Our results suggest that complications associated with intravenous midazolam and fentanyl sedation using the titration technique for minor oral surgeries are mostly minor and can be successfully managed with no prolonged sequelae. PMID:29090250

A randomised controlled trial evaluating IGF1 titration in contrast to current GH dosing strategies in children born small for gestational age: the North European Small-for-Gestational-Age Study.

PubMed

Jensen, Rikke Beck; Thankamony, Ajay; O'Connell, Susan M; Kirk, Jeremy; Donaldson, Malcolm; Ivarsson, Sten-A; Söder, Olle; Roche, Edna; Hoey, Hilary; Dunger, David B; Juul, Anders

2014-10-01

Short children born small for gestational age (SGA) are treated with a GH dose based on body size, but treatment may lead to high levels of IGF1. The objective was to evaluate IGF1 titration of GH dose in contrast to current dosing strategies. In the North European Small-for-Gestational-Age Study (NESGAS), 92 short pre-pubertal children born SGA were randomised after 1 year of high-dose GH treatment (67 μg/kg per day) to three different regimens: high dose (67 μg/kg per day), low dose (35 μg/kg per day) or IGF1 titration. The average dose during the second year of the randomised trial did not differ between the IGF1 titration group (38 μg/kg per day, s.d. 0.019) and the low-dose group (35 μg/kg per day, s.d. 0.002; P=0.46), but there was a wide variation in the IGF1 titration group (range 10-80 μg/kg per day). The IGF1 titration group had significantly lower height gain (0.17 SDS, s.d. 0.18) during the second year of the randomised trial compared with the high-dose group (0.46 SDS, s.d. 0.25), but not significantly lower than the low-dose group (0.23 SDS, s.d. 0.15; P=0.17). The IGF1 titration group had lower IGF1 levels after 2 years of the trial (mean 1.16, s.d. 1.24) compared with both the low-dose (mean 1.76, s.d. 1.48) and the high-dose (mean 2.97, s.d. 1.63) groups. IGF1 titration of GH dose in SGA children proved less effective than current dosing strategies. IGF1 titration resulted in physiological IGF1 levels with a wide range of GH dose and a poorer growth response, which indicates the role of IGF1 resistance and highlights the heterogeneity of short SGA children. © 2014 European Society of Endocrinology.

Determination of biguanide groups in polyhexamethylene biguanide hydrochloride by titrimetric methods.

PubMed

Hattori, Toshiaki; Nakata, Yasuko; Kato, Ryo

2003-11-01

The biguanide concentration of polyhexamethylene biguanide hydrochloride (PHMB-HCl) was measured by non-aqueous titration with HClO4, argentometric titration, the Kjeldhal method, and colloidal titration. The summation value of non-aqueous titration and argentometric titration corresponded to two titrable nitrogens in five nitrogens per one unit of PHMB-HCl, and consisted with the result of the Kjeldhal method to the five nitrogens. The colloidal titration of PHMB-HCl at pH 2.05 was equal to that with the two nitrogens. The relative standard deviations of non-aqueous titration, argentometric titration, the Kjeldhal method, and colloidal titration were 0.50% for 8 runs, 0.13% for 7 runs, 3.61% for 6 runs, and 0.69% for 6 runs, respectively.

Thermometric titration of acids in pyridine.

PubMed

Vidal, R; Mukherjee, L M

1974-04-01

Thermometric titration of HClO(4), HI, HNO(3), HBr, picric acid o-nitrobenzoic acid, 2,4- and 2,5-dinitrophenol, acetic acid and benzoic acid have been attempted in pyridine as solvent, using 1,3-diphenylguanidine as the base. Except in the case of 2,5-dinitrophenol, acetic acid and benzoic acid, the results are, in general, reasonably satisfactory. The approximate molar heats of neutralization have been calculated.

Determination of hydroxide and carbonate contents of alkaline electrolytes containing zinc

NASA Technical Reports Server (NTRS)

Otterson, D. A.

1975-01-01

A method to prevent zinc interference with the titration of OH- and CO3-2 ions in alkaline electrolytes with standard acid is presented. The Ba-EDTA complex was tested and shown to prevent zinc interference with acid-base titrations without introducing other types of interference. Theoretical considerations indicate that this method can be used to prevent interference by other metals.

Thermometric titration in investigation of the formation of polyanions of molybdenum(VI), tungsten(VI), vanadium(V), and chromium (VI)-I: comparison of thermometric and potentiometric titration curves.

PubMed

Kiba, N; Takeuchi, T

1973-09-01

A new twin-cell thermometric titrator has been devised and used for thermometric titration of solutions of sodium molybdate, sodium tungstate, sodium orthovanadate, ammonium metavanadate, and potassium chromate with perchloric acid. The thermometric titration curves were compared with corresponding pH-titration curves for elucidation of the reactions occurring in the titrations. Thermometric titrimetric methods have been developed for the determination of tungsten, vanadium and chromium.

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

PubMed

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

2014-11-18

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

Thermometric titration of sulphate.

PubMed

Williams, M B; Janata, J

1970-06-01

Direct thermometric titration of sulphate with a solution of barium perchlorate is proposed. The stoichiometry of the titration is shown to be critically dependent on the concentration of ethanol in the titration medium. The titration is rapid and suffers from only a few interferences.

Small-volume potentiometric titrations: EPR investigations of Fe-S cluster N2 in mitochondrial complex I.

PubMed

Wright, John J; Salvadori, Enrico; Bridges, Hannah R; Hirst, Judy; Roessler, Maxie M

2016-09-01

EPR-based potentiometric titrations are a well-established method for determining the reduction potentials of cofactors in large and complex proteins with at least one EPR-active state. However, such titrations require large amounts of protein. Here, we report a new method that requires an order of magnitude less protein than previously described methods, and that provides EPR samples suitable for measurements at both X- and Q-band microwave frequencies. We demonstrate our method by determining the reduction potential of the terminal [4Fe-4S] cluster (N2) in the intramolecular electron-transfer relay in mammalian respiratory complex I. The value determined by our method, E m7 =-158mV, is precise, reproducible, and consistent with previously reported values. Our small-volume potentiometric titration method will facilitate detailed investigations of EPR-active centres in non-abundant and refractory proteins that can only be prepared in small quantities. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Estimating iron and aluminum content of acid mine discharge from a north-central Pennsylvania coal field by use of acidity titration curves

USGS Publications Warehouse

Ott, A.N.

1986-01-01

Determination of acidity provides a value that denotes the quantitative capacity of the sample water to neutralize a strong base to a particular pH. However, much additional information can be obtained from this determination if a titration curve is constructed from recorded data of titrant increments and their corresponding pH values. The curve can be used to identify buffer capabilities, the acidity with respect to any pH value within the curve limit, and, in the case of acid mine drainage from north-central Pennsylvania, the identification and estimation of the concentration of dissolved ferrous iron, ferric iron, and aluminum. Through use of titration curves, a relationship was observed for the acid mine drainage between: (1) the titratable acidity (as milligrams per liter calcium carbonate) to pH 4.0 and the concentration of dissolved ferric iron; and (2) the titratable acidity (as milligrams per liter calcium carbonate) from pH 4.0 to 5.0 and the concentration of dissolved aluminum. The presence of dissolved ferrous iron can be detected by the buffering effect exhibited in the area between pH 5.5 to 7.5. The concentration of ferrous iron is estimated by difference between the concentrations of ferric iron in an oxidized and unoxidized sample. Interferences in any of the titrations from manganese, magnesium, and aluminate, appear to be negligible within the pH range of interest.

Protofit: A program for determining surface protonation constants from titration data

NASA Astrophysics Data System (ADS)

Turner, Benjamin F.; Fein, Jeremy B.

2006-11-01

Determining the surface protonation behavior of natural adsorbents is essential to understand how they interact with their environments. ProtoFit is a tool for analysis of acid-base titration data and optimization of surface protonation models. The program offers a number of useful features including: (1) enables visualization of adsorbent buffering behavior; (2) uses an optimization approach independent of starting titration conditions or initial surface charge; (3) does not require an initial surface charge to be defined or to be treated as an optimizable parameter; (4) includes an error analysis intrinsically as part of the computational methods; and (5) generates simulated titration curves for comparison with observation. ProtoFit will typically be run through ProtoFit-GUI, a graphical user interface providing user-friendly control of model optimization, simulation, and data visualization. ProtoFit calculates an adsorbent proton buffering value as a function of pH from raw titration data (including pH and volume of acid or base added). The data is reduced to a form where the protons required to change the pH of the solution are subtracted out, leaving protons exchanged between solution and surface per unit mass of adsorbent as a function of pH. The buffering intensity function Qads* is calculated as the instantaneous slope of this reduced titration curve. Parameters for a surface complexation model are obtained by minimizing the sum of squares between the modeled (i.e. simulated) buffering intensity curve and the experimental data. The variance in the slope estimate, intrinsically produced as part of the Qads* calculation, can be used to weight the sum of squares calculation between the measured buffering intensity and a simulated curve. Effects of analytical error on data visualization and model optimization are discussed. Examples are provided of using ProtoFit for data visualization, model optimization, and model evaluation.

Use of computer-assisted drug therapy outside the operating room.

PubMed

Singh, Preet Mohinder; Borle, Anuradha; Goudra, Basavana G

2016-08-01

The number of procedures performed in the out-of-operating room setting under sedation has increased many fold in recent years. Sedation techniques aim to achieve rapid patient turnover through the use of short-acting drugs with minimal residual side-effects (mainly propofol and opioids). Even for common procedures, the practice of sedation delivery varies widely among providers. Computer-based sedation models have the potential to assist sedation providers and offer a more consistent and safer sedation experience for patients. Target-controlled infusions using propofol and other short-acting opioids for sedation have shown promising results in terms of increasing patient safety and allowing for more rapid wake-up times. Target-controlled infusion systems with real-time patient monitoring can titrate drug doses automatically to maintain optimal depth of sedation. The best recent example of this is the propofol-based Sedasys sedation system. Sedasys redefined individualized sedation by the addition of an automated clinical parameter that monitors depth of sedation. However, because of poor adoption and cost issues, it has been recently withdrawn by the manufacturer. Present automated drug delivery systems can assist in the provision of sedation for out-of-operating room procedures but cannot substitute for anesthesia providers. Use of the available technology has the potential to improve patient outcomes, decrease provider workload, and have a long-term economic impact on anesthesia care delivery outside of the operating room.

Interplay of charge distribution and conformation in peptides: comparison of theory and experiment.

PubMed

Makowska, Joanna; Bagińska, Katarzyna; Kasprzykowski, F; Vila, Jorge A; Jagielska, Anna; Liwo, Adam; Chmurzyński, Lech; Scheraga, Harold A

2005-01-01

We assessed the correlation between charge distribution and conformation of flexible peptides by comparing the theoretically calculated potentiometric-titration curves of two model peptides, Ac-Lys5-NHMe (a model of poly-L-lysine) and Ac-Lys-Ala11-Lys-Gly2-Tyr-NH2 (P1) in water and methanol, with the experimental curves. The calculation procedure consisted of three steps: (i) global conformational search of the peptide under study using the electrostatically driven Monte Carlo (EDMC) method with the empirical conformational energy program for peptides (ECEPP)/3 force field plus the surface-hydration (SRFOPT) or the generalized Born surface area (GBSA) solvation model as well as a molecular dynamics method with the assisted model building and energy refinement (AMBER)99/GBSA force field; (ii) reevaluation of the energy in the pH range considered by using the modified Poisson-Boltzmann approach and taking into account all possible protonation microstates of each conformation, and (iii) calculation of the average degree of protonation of the peptide at a given pH value by Boltzmann averaging over conformations. For Ac-Lys5-NHMe, the computed titration curve agrees qualitatively with the experimental curve of poly-L-lysine in 95% methanol. The experimental titration curves of peptide P1 in water and methanol indicate a remarkable downshift of the first pK(a) value compared to the values for reference compounds (n-butylamine and phenol, respectively), suggesting the presence of a hydrogen bond between the tyrosine hydroxyl oxygen and the H(epsilon) proton of a protonated lysine side chain. The theoretical titration curves agree well with the experimental curves, if conformations with such hydrogen bonds constitute a significant part of the ensemble; otherwise, the theory predicts too small a downward pH shift. Copyright 2005 Wiley Periodicals, Inc

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

PubMed

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

2011-11-01

Gene therapy represents a promising approach in the treatment of several diseases. Currently, the ideal vector has yet to be designed; though, adenoviral vectors (Ad-v) have provided the most utilized tool for gene transfer due principally to their simple production, among other specific characteristics. Ad-v viability represents a critical variable that may be affected by storage or shipping conditions and therefore it is advisable to be assessed previously to protocol performance. The present work is unique in this matter, as the complete detailed process to obtain Ad-v of preclinical grade is explained. Amplification in permissive HEK-293 cells, purification in CsCl gradients in a period of 10 h, spectrophotometric titration of viral particles (VP) and titration of infectious units (IU), yielding batches of AdβGal, AdGFP, AdHuPA and AdMMP8, of approximately 10¹³-10¹⁴ VP and 10¹²-10¹³ IU were carried out. In vivo functionality of therapeutic AdHuPA and AdMMP8 was evidenced in rats presenting CCl₄-induced fibrosis, as more than 60% of fibrosis was eliminated in livers after systemic delivery through iliac vein in comparison with irrelevant AdβGal. Time required to accomplish the whole Ad-v production steps, including IU titration was 20 to 30 days. We conclude that production of Ad-v following standard operating procedures assuring vector functionality and the possibility to effectively evaluate experimental gene therapy results, leaving aside the use of high-cost commercial kits or sophisticated instrumentation, can be performed in a conventional laboratory of cell culture. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Processes for Assessing the Thermal Stability of Han-Based Liquid Propellants. Revision

DTIC Science & Technology

1990-07-01

indicators is not adequate, and potentiometric determination cr’ the equivalence point is the most suitable method (Kraft and Fischer 1972). The use of...be determined by Karl Fischer titration. This method requires a special titration apparatus because the Titroprozessor 636 is not suited for this type... methods obtained from the literature (Kraft and Fischer 1972), and, where necessary, the manufacturer has modified evaluation methods (Firmenschrift

Stabilization of the initial electrochemical potential for a metal-based potentiometric titration study of a biosorption process.

PubMed

Naja, Ghinwa; Mustin, Christian; Volesky, Bohumil; Berthelin, Jacques

2006-01-01

An interactive metal-based potentiometric titration method has been developed using an ion selective electrode for studying the sorption of metal cations. The accuracy of this technique was verified by analyzing the metal sorption mechanism for the biomass of Rhizopus arrhizus fungus and diatomite, two dissimilar materials (organic and mineral, strong sorbent and weak sorbent) of a different order of cation exchange capacity. The problem of the initial electrochemical potential was addressed identifying the usefulness of a Na-sulfonic resin as a strong chelating agent applied before the beginning of sorption titration experiments so that the titration curves and the sorption uptake could be quantitatively compared. The resin stabilized the initial electrochemical potential to -405+/-5 mV corresponding to 2 micro gl(-1) of lead concentration in solution. The amounts of lead sorbed by R. arrhizus biomass and diatomite were 0.9 mmol g(-1) (C(e)=5.16 x 10(-2)mM) and 0.052 mmol g(-1) (C(e)=5.97 x 10(-2) mM), respectively. Lead sorption by the fungal biomass was pinpointed to at least two types of chemical active sites. The first type was distinguished by high reactivity and a low number of sites whereas the other was characterized by their higher number and lower reactivity.

Characterization of acid functional groups of carbon dots by nonlinear regression data fitting of potentiometric titration curves

NASA Astrophysics Data System (ADS)

Alves, Larissa A.; de Castro, Arthur H.; de Mendonça, Fernanda G.; de Mesquita, João P.

2016-05-01

The oxygenated functional groups present on the surface of carbon dots with an average size of 2.7 ± 0.5 nm were characterized by a variety of techniques. In particular, we discussed the fit data of potentiometric titration curves using a nonlinear regression method based on the Levenberg-Marquardt algorithm. The results obtained by statistical treatment of the titration curve data showed that the best fit was obtained considering the presence of five Brønsted-Lowry acids on the surface of the carbon dots with constant ionization characteristics of carboxylic acids, cyclic ester, phenolic and pyrone-like groups. The total number of oxygenated acid groups obtained was 5 mmol g-1, with approximately 65% (∼2.9 mmol g-1) originating from groups with pKa < 6. The methodology showed good reproducibility and stability with standard deviations below 5%. The nature of the groups was independent of small variations in experimental conditions, i.e. the mass of carbon dots titrated and initial concentration of HCl solution. Finally, we believe that the methodology used here, together with other characterization techniques, is a simple, fast and powerful tool to characterize the complex acid-base properties of these so interesting and intriguing nanoparticles.

Multi-complexity measures of heart rate variability and the effect of vasopressor titration: a prospective cohort study of patients with septic shock.

PubMed

Brown, Samuel M; Sorensen, Jeffrey; Lanspa, Michael J; Rondina, Matthew T; Grissom, Colin K; Shahul, Sajid; Mathews, V J

2016-10-10

Septic shock is a common and often devastating syndrome marked by severe cardiovascular dysfunction commonly managed with vasopressors. Whether markers of heart rate complexity before vasopressor up-titration could be used to predict success of the up-titration is not known. We studied patients with septic shock requiring vasopressor, newly admitted to the intensive care unit. We measured the complexity of heart rate variability (using the ratio of fractal exponents from detrended fluctuation analysis) in the 5 min before all vasopressor up-titrations in the first 24 h of an intensive care unit (ICU) admission. A successful up-titration was defined as one that did not require further up-titration (or decrease in mean arterial pressure) for 60 min. We studied 95 patients with septic shock, with a median APACHE II of 27 (IQR: 20-37). The median number of up-titrations, normalized to 24 h, was 12.2 (IQR: 8-17) with a maximum of 49. Of the up-titrations, the median proportion of successful interventions was 0.28 (IQR: 0.12-0.42). The median of mean arterial pressure (MAP) at the time of a vasopressor up-titration was 66 mmHg; the average infusion rate of norepinephrine at the time of an up-titration was 0.11 mcg/kg/min. The ratio of fractal exponents was not associated with successful up-titration on univariate or multivariate regression. On exploratory secondary analyses, however, the long-term fractal exponent was associated (p = 0.003) with success of up-titration. Independent of heart rate variability, MAP was associated (p < 0.001) with success of vasopressor up-titration, while neither Sequential Organ Failure Assessment (SOFA) nor Acute Physiology and Chronic Health Evaluation II (APACHE II) score was associated with vasopressor titration. Only a third of vasopressor up-titrations were successful among patients with septic shock. MAP and the long-term fractal exponent were associated with success of up-titration. These two, complementary variables may be important to the development of rational vasopressor titration protocols.

Differential electrolytic potentiometric titration method for the determination of ciprofloxacin in drug formulations.

PubMed

Abulkibash, Abdalla M; Sultan, Salah M; Al-Olyan, Abeer M; Al-Ghannam, Sheikha M

2003-10-17

A simple and rapid differential electrolytic potentiometric titration method for the determination of ciprofloxacin was developed. The work is based on the fast complexation reaction between iron(III) and ciprofloxacin in a ratio of 1:3, respectively, in sulfuric acid media of 0.09 mol dm(-3). Among the electrodes tested silver amalgam electrodes were found to be a suitable indicating system. By applying a current density of 0.5 muA cm(-2) to these electrodes and using iron(III) solution of 0.097 mol dm(-3) as a titrant, normal titration curves were obtained. The method was successfully applied for the determination of ciprofloxacin in drug formulations as low as 4.0 ppm.

A titration method for determining individual oxidant concentration in the dual sodium persulfate and hydrogen peroxide oxidation system.

PubMed

Liang, Chenju; He, Boyu

2018-05-01

The use of a dual oxidation system, which combines sodium persulfate (Na 2 S 2 O 8 , SPS) and hydrogen peroxide (H 2 O 2 , HP) is increasing as an in-situ chemical oxidation (ISCO) process for soil and groundwater remediation. An analytical method was assessed in this study for determining individual oxidant concentration in order to understand the interactions, and variations in the concentrations, of SPS and HP in aqueous systems containing both SPS and HP. The iodometric titration method was demonstrated to be capable of measuring total oxidant (SPS + HP) concentration; while the ceric sulfate titration method can be used specifically for measuring HP in the dual oxidation system without interfering with the iodometric titration. Therefore, SPS concentration can be deduced by subtraction of the HP concentration from the total oxidant concentration. Direct iodometric titration for determination of total oxidant at concentration above 20 mM exhibited <8% concentration. Based on the results of indirect determination of SPS in the dual oxidation system, an approximate 10% concentration variation was expected. This research may serve as a reference for measuring oxidant variations in this ISCO dual oxidant application. Copyright © 2018. Published by Elsevier Ltd.

Managed care cost-containment strategies and their impact on physician prescribing and treatment of depression. Based on a presentation by Robert K. Schreter, MD.

PubMed

2000-02-01

Pharmacy costs are outpacing other healthcare expenditures, with psychotropic medications accounting for 16% to 25% of the total pharmacy costs. Managed care organizations (MCOs) can be expected to exert considerable pressure to control such costs. Avenues for cost containment include changing the management and spending decisions of MCOs, influencing physician prescribing patterns, encouraging economically efficient pharmacy policies and procedures, and controlling patient access to prescription drugs. From the cost standpoint of an MCO, briefer approaches to treating depressed patients are desirable. The MCOs prefer a limited number of psychotherapeutic sessions, rapid titration and prescription of higher dosage levels of appropriate drugs, and a longer continuation phase of pharmacological treatment to avert a relapse.

Multivariate curve resolution of incomplete fused multiset data from chromatographic and spectrophotometric analyses for drug photostability studies.

PubMed

De Luca, Michele; Ragno, Gaetano; Ioele, Giuseppina; Tauler, Romà

2014-07-21

An advanced and powerful chemometric approach is proposed for the analysis of incomplete multiset data obtained by fusion of hyphenated liquid chromatographic DAD/MS data with UV spectrophotometric data from acid-base titration and kinetic degradation experiments. Column- and row-wise augmented data blocks were combined and simultaneously processed by means of a new version of the multivariate curve resolution-alternating least squares (MCR-ALS) technique, including the simultaneous analysis of incomplete multiset data from different instrumental techniques. The proposed procedure was applied to the detailed study of the kinetic photodegradation process of the amiloride (AML) drug. All chemical species involved in the degradation and equilibrium reactions were resolved and the pH dependent kinetic pathway described. Copyright © 2014 Elsevier B.V. All rights reserved.

Sensitivity of the acid-base properties of clays to the methods of preparation and measurement. 1. Literature review.

PubMed

Duc, Myriam; Gaboriaud, Fabien; Thomas, Fabien

2005-09-01

Measuring and modeling the surface charge of clays, and more especially smectites, has become an important issue in the use of bentonites as a waste confinement material aimed at retarding migration of water and solutes. Therefore, many studies of the acid-base properties of montmorillonite have appeared recently in the literature, following older studies principally devoted to cation exchange. It is striking that beyond the consensus about the complex nature of the surface charge of clays, there are many discrepancies, especially concerning the dissociable charge, that prevents intercomparison among the published data. However, a general trend is observed regarding the absence of common intersection point on raw titration curves at different ionic strengths. Analysis of the literature shows that these discrepancies originate from the experimental procedures for the preparation of the clays and for the quantification of their surface charge. The present work is an attempt to understand how these procedures can impact the final results. Three critical operations can be identified as having significant effects on the surface properties of the studied clays. The first one is the preparation of purified clay from the raw material: the use of acid or chelation treatments, and the repeated washings in deionized water result in partial dissolution of the clays. Then storage of the purified clay in dry or wet conditions strongly influences the equilibria in the subsequent experiments respectively by precipitation or enhanced dissolution. The third critical operation is the quantification of the surface charge by potentiometric titration, which requires the use of strong acids and bases. As a consequence, besides dissociation of surface sites, many secondary titrant consuming reactions were described in the literature, such as cation exchange, dissolution, hydrolysis, or precipitation. The cumulated effects make it difficult to derive proper dissociation constants, and to build adequate models. The inadequation of the classical surface complexation models to describe the acid-base behavior of clays is illustrated by the electrokinetic behavior of smectites, which is independent from the pH and the ionic strength. Therefore, there is still a need on one hand for accurate data recorded in controlled conditions, and on the other hand for new models taking into account the complex nature of the charge of clays.

Titratable acidity of beverages influences salivary pH recovery.

PubMed

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

2015-01-01

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

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

PubMed

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

2002-12-06

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 1200 mg l(-1) was achieved. The relative standard deviation for 11 replicate determinations of 400 mg l(-1) ascorbic acid was 2.9%. The second system, for acetic acid determination, was based on acid-base titration of acetic acid with sodium hydroxide using phenolphthalein as an indicator. The decrease in color intensity of the indicator was proportional to the acid content. A linear calibration graph in the range of 2-8% w v(-1) of acetic acid with a relative standard deviation of 4.8% (5.0% w v(-1) acetic acid, n=11) was obtained. Sample throughputs of 60 h(-1) were achieved for both systems. The systems were successfully applied for the assays of ascorbic acid in vitamin C tablets and acetic acid content in vinegars, respectively.

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

NASA Technical Reports Server (NTRS)

Demore, W. B.; Patapoff, M.

1976-01-01

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.

Atomic and Molecular Gas Phase Spectrometry.

DTIC Science & Technology

1983-09-30

between the thermometric levels, k is the Boltzmann constant (k = 0.695 cm-I K-1 ), Aik (s- 1) is the transition probability for spontaneous emission from...monitoring of the atomic absorption of M; information about the reaction processes were deduced from the shapes of the titration curves; (5) measure- ment of...Changes During Titration Based Upon The Releasing Effect Atomic Absorption Spectroscopy," D. Stojanovic and J.D. Winefordner, Anal Chim. Acta, 114, 295

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

PubMed

Brix, Kevin V; Wood, Chris M; Grosell, Martin

2013-01-01

In this study, Na(+) uptake and acid-base balance in the euryhaline pupfish Cyprinodon variegatus variegatus were characterized when fish were exposed to pH 4.5 freshwater (7mM Na(+)). Similar to the related cyprinodont, Fundulus heteroclitus, Na(+) uptake was significantly inhibited when exposed to low pH water. However, it initially appeared that C. v. variegatus increased apparent net acid excretion at low pH relative to circumneutral pH. This result is opposite to previous observations for F. heteroclitus under similar conditions where fish were observed to switch from apparent net H(+) excretion at circumneutral pH to apparent net H(+) uptake at low pH. Further investigation revealed disparate observations between these studies were the result of using double endpoint titrations to measure titratable alkalinity fluxes in the current study, while the earlier study utilized single endpoint titrations to measure these fluxes (i.e.,. Cyprinodon acid-base transport is qualitatively similar to Fundulus when characterized using single endpoint titrations). This led to a comparative investigation of these two methods. We hypothesized that either the single endpoint methodology was being influenced by a change in the buffer capacity of the water (e.g., mucus being released by the fish) at low pH, or the double endpoint methodology was not properly accounting for ammonia flux by the fish. A series of follow-up experiments indicated that buffer capacity of the water did not change significantly, that excretion of protein (a surrogate for mucus) was actually reduced at low pH, and that the double endpoint methodology does not properly account for NH(3) excretion by fish under low pH conditions. As a result, it overestimates net H(+) excretion during low pH exposure. After applying the maximum possible correction for this error (i.e., assuming that all ammonia is excreted as NH(3)), the double endpoint methodology indicates that net H(+) transport was reduced to effectively zero in both species at pH 4.5. However, significant differences between the double endpoint (no net H(+) transport at low pH) and single endpoint titrations (net H(+) uptake at low pH) remain to be explained. Copyright © 2012 Elsevier Inc. All rights reserved.

Detecting Levels of Polyquaternium-10 (PQ-10) via Potentiometric Titration with Dextran Sulphate and Monitoring the Equivalence Point with a Polymeric Membrane-Based Polyion Sensor.

PubMed

Ferguson, Stephen A; Wang, Xuewei; Meyerhoff, Mark E

2016-08-07

Polymeric quaternary ammonium salts (polyquaterniums) have found increasing use in industrial and cosmetic applications in recent years. More specifically, polyquaternium-10 (PQ-10) is routinely used in cosmetic applications as a conditioner in personal care product formulations. Herein, we demonstrate the use of potentiometric polyion-sensitive polymeric membrane-based electrodes to quantify PQ-10 levels. Mixtures containing both PQ-10 and sodium lauryl sulfate (SLS) are used as model samples to illustrate this new method. SLS is often present in cosmetic samples that contain PQ-10 (e.g., shampoos, etc.) and this surfactant species interferes with the polyion sensor detection chemistry. However, it is shown here that SLS can be readily separated from the PQ-10/SLS mixture by use of an anion-exchange resin and that the PQ-10 can then be titrated with dextran sulphate (DS). This titration is monitored by potentiometric polyanion sensors to provide equivalence points that are directly proportional to PQ-10 concentrations.

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

NASA Astrophysics Data System (ADS)

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

2007-12-01

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.

Intravenous infusion of prostaglandin E2 for management of premature rupture of membranes.

PubMed

Thiery, M; Parewijck, W; Martens, G

1982-01-01

In term with premature rupture of the membranes (PROM) and an unripe cervix who have no contraindications for prostaglandin (PG) administration and vaginal delivery, intravenous (I.V.) infusion of titrated PGE2 is highly effective. In healthy gravidas with dito fetus this treatment appeared perinatally safe and was well tolerated by the mother. To enhance its safety margin and procedure must be conducted under toco-cardiographic control.

[Comparison of different continuous positive airway pressure titration methods for obstructive sleep apnea hypopnea syndrome].

PubMed

Li, Jingjing; Ye, Jingying; Zhang, Peng; Kang, Dan; Cao, Xin; Zhang, Yuhuan; Ding, Xiu; Zheng, Li; Li, Hongguang; Bian, Qiuli

2014-10-01

To explore whether there were differences between the results of automatic titration and the results of manual titration for positive airway pressure treatment in patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and its influencing factors, the results might provide a theoretical basis for the rational use of two pressure titration methods. Sixty one patients with OSAHS were included in this study. All patients underwent a manual titration and an automatic titration within one week. The clinical informations, polysomnography data, and the results of both two titration of all patients were obtained for analysis. The overall apnea/hypopnea index was (63.1 ± 17.7)/h, with a range of 14.9/h to 110.4/h. The treatment pressure of manual titration was (8.4 ± 2.1) cmH(2)O, which was significantly lower than the treatment pressure of automatic titration, (11.5 ± 2.7) cmH(2)O (t = -9.797, P < 0.001). After using a ΔP of 3 cmH(2)O for the cutoff value (ΔP was defined as the difference of automatic titration and manual titration), it was found that the pressure of automatic titration was significantly higher in patients with a ΔP > 3 cmH(2)O than in patients with a ΔP ≤ 3 cmH(2)O, which was (13.3 ± 2.3) cmH(2)O vs (10.0 ± 2.0) cmH(2)O (t = -6.159, P < 0.001). However, there were no differences for the pressure of manual titration between these two groups, which was (8.6 ± 2.4) cmH(2)O vs (8.3 ± 2.0)cmH(2)O (P > 0.05). There was no significant difference in age, body mass index, neck circumference, abdomen circumference, apnea hypopnea index, and arterial oxygen saturation between these two groups. The treatment pressure of automatic titration is usually higher than that of manual titration. For patients with a high treatment pressure which is derived from automatic titration, a suggestion about manual titration could be given to decrease the potential treatment pressure of continuous positive airway pressure, which may be helpful in improving the comfortableness and the compliance of this treatment.

Limitations of pH-potentiometric titration for the determination of the degree of deacetylation of chitosan.

PubMed

Balázs, Nándor; Sipos, Pál

2007-01-15

The degree of deacetylation (DDA) of chitosan determines the biopolymer's physico-chemical properties and technological applications. pH-Potentiometric titration seems to offer a simple and convenient means of determining DDA. However, to obtain accurate pH-potentiometric DDA values, several factors have to be taken into consideration. We found that the moisture content of the air-dry chitosan samples can be as high as 15%, and a reasonable fraction of this humidity cannot be removed by ordinary drying. Corrections have to be made for the ash content, as in some samples it can be as high as 1% by weight. The method of equivalence point determination was also found to cause systematic variations in the results and in some samples extra acid as high as 1 mol% of the free amino content was also identified. To compensate for the latter effect, the second equivalence point of the titration has to be determined separately and the analytical concentration of the acid be corrected for it. All the corrections listed here are necessary to obtain DDA values that are in reasonable agreement with those obtained from (1)H NMR and IR spectroscopic measurements. The need for these corrections severely limits the usefulness of pH-metry for determining accurate DDA values and thus potentiometry is hardly able to compete with other standard spectroscopic procedures, that is, (1)H NMR spectroscopy.

Modified spectrophotometer for multi-dimensional circular dichroism/fluorescence data acquisition in titration experiments: application to the pH and guanidine-HCI induced unfolding of apomyoglobin.

PubMed

Ramsay, G; Ionescu, R; Eftink, M R

1995-08-01

In a previous paper (Ramsay and Eftink, Biophys. J. 66:516-523) we reported the development of a modified spectrophotometer that can make nearly simultaneous circular dichroism (CD) and fluorescence measurements. This arrangement allows multiple data sets to be collected during a single experiment, resulting in a saving of time and material, and improved correlation between the different types of measurements. The usefulness of the instrument was shown by thermal melting experiments on several different protein systems. This CD/fluorometer spectrophotometer has been further modified by interfacing with a syringe pump and a pH meter. This arrangement allows ligand, pH, and chemical denaturation titration experiments to be performed while monitoring changes in the sample's CD, absorbance, fluorescence, and light scattering properties. Our data acquisition program also has an ability to check whether the signals have approached equilibrium before the data is recorded. For performing pH titrations we have developed a procedure which uses the signal from a pH meter in a feedback circuit in order to collect data at evenly spaced pH intervals. We demonstrate the use of this instrument with studies of the unfolding of sperm whale apomyoglobin, as induced by acid pH and by the addition of guanidine-HCI.

Modified spectrophotometer for multi-dimensional circular dichroism/fluorescence data acquisition in titration experiments: application to the pH and guanidine-HCI induced unfolding of apomyoglobin.

PubMed Central

Ramsay, G; Ionescu, R; Eftink, M R

1995-01-01

In a previous paper (Ramsay and Eftink, Biophys. J. 66:516-523) we reported the development of a modified spectrophotometer that can make nearly simultaneous circular dichroism (CD) and fluorescence measurements. This arrangement allows multiple data sets to be collected during a single experiment, resulting in a saving of time and material, and improved correlation between the different types of measurements. The usefulness of the instrument was shown by thermal melting experiments on several different protein systems. This CD/fluorometer spectrophotometer has been further modified by interfacing with a syringe pump and a pH meter. This arrangement allows ligand, pH, and chemical denaturation titration experiments to be performed while monitoring changes in the sample's CD, absorbance, fluorescence, and light scattering properties. Our data acquisition program also has an ability to check whether the signals have approached equilibrium before the data is recorded. For performing pH titrations we have developed a procedure which uses the signal from a pH meter in a feedback circuit in order to collect data at evenly spaced pH intervals. We demonstrate the use of this instrument with studies of the unfolding of sperm whale apomyoglobin, as induced by acid pH and by the addition of guanidine-HCI. Images FIGURE 2 PMID:8527683

An Improved MUSIC Model for Gibbsite Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, Scott C.; Bickmore, Barry R.; Tadanier, Christopher J.

2004-06-01

Here we use gibbsite as a model system with which to test a recently published, bond-valence method for predicting intrinsic pKa values for surface functional groups on oxides. At issue is whether the method is adequate when valence parameters for the functional groups are derived from ab initio structure optimization of surfaces terminated by vacuum. If not, ab initio molecular dynamics (AIMD) simulations of solvated surfaces (which are much more computationally expensive) will have to be used. To do this, we had to evaluate extant gibbsite potentiometric titration data that where some estimate of edge and basal surface area wasmore » available. Applying BET and recently developed atomic force microscopy methods, we found that most of these data sets were flawed, in that their surface area estimates were probably wrong. Similarly, there may have been problems with many of the titration procedures. However, one data set was adequate on both counts, and we applied our method of surface pKa int prediction to fitting a MUSIC model to this data with considerable success—several features of the titration data were predicted well. However, the model fit was certainly not perfect, and we experienced some difficulties optimizing highly charged, vacuum-terminated surfaces. Therefore, we conclude that we probably need to do AIMD simulations of solvated surfaces to adequately predict intrinsic pKa values for surface functional groups.« less

Indirect potentiometric titration of ascorbic acid in pharmaceutical preparations using copper based mercury film electrode.

PubMed

Abdul Kamal Nazer, Meeran Mohideen; Hameed, Abdul Rahman Shahul; Riyazuddin, Patel

2004-01-01

A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance.

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

PubMed

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

2006-11-01

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

[Synthesis and Spectroscopic Study of a Chemosensor for Naked Eye Recognition of Cu2+ and Hg2+].

PubMed

Cao, Li; Qian, Ya-ao; Huang, Yan; Cao, Juan; Jia, Chun-man; Liu, Chun-ling; Zhang, Qi; Lu, Zheng-rong

2015-07-01

Compound L, as the procedural sensor for the detection of Cu2+ and Hg2+, was designed and synthesized based on the coumarin-modified rhodamine derivative. The structure of compound L was characterized by NMR, high resolution mass spectrometry and infrared method. Its sensing behavior toward various metal ions was investigated with absorbance methods. The study found that L had good selectivity and sensitivity for Cu2+. When addition of various metal ions (Zn2+, Hg2+, Cu2+, Fe3+, Cd2+, CO2+, Ni2+, Mg2+, Ca2+, Al3+, La3+, K+, Na+, Mn2+, Pb2+ and Ag+), only Cu2+ could induce a visible change of solution from colourless to pink and a new absorption band centered at 534 nm appear, which indicated that compound L could be used for the naked eye detection of Cu2+. From UV titration, the detection limit was about 1.9 X 10(-8) mol x L(-1). Test strips based on L were fabricated, and this test strips could act as a convenient and efficient Cu2+ test kit. The binding ratio of the complex of L-Cu2+ was 1:1 according to the Job's plot and high resolution mass spectrometer (HRMS) experiments. Moreover, Upon addition of 1 equiv. EDTA to the mixture of L and Cu2+ in DMSO solution, colour changed from pink to almost colourless, indicating that the EDTA replaced the receptor L to coordinate with Cu2+. Therefore, L could be classified as a reversible sensor for Cu2+. In addition, when adding Hg2+ to L-Cu2+ complexes, a visible change of solution from pink to colourless was observed, while other metal ions didn't cause this change. Thus, L-Cu2+ complex also could be used for the naked eye recognition of Hg2+, and the detection limit was calculated about 2.9 x 10(-1) mol x L(-1) according to the UV titration. Consequently, this procedural sensor L could be use for the orderly naked eye recognition of Cu2+ and Hg2+.

Comparison of manual versus automatic continuous positive airway pressure titration and the development of a predictive equation for therapeutic continuous positive airway pressure in Chinese patients with obstructive sleep apnoea.

PubMed

Luo, Jiaying; Xiao, Sichang; Qiu, Zhihui; Song, Ning; Luo, Yuanming

2013-04-01

Whether the therapeutic nasal continuous positive airway pressure (CPAP) derived from manual titration is the same as derived from automatic titration is controversial. The purpose of this study was to compare the therapeutic pressure derived from manual titration with automatic titration. Fifty-one patients with obstructive sleep apnoea (OSA) (mean apnoea/hypopnoea index (AHI) = 50.6 ± 18.6 events/h) who were newly diagnosed after an overnight full polysomnography and who were willing to accept CPAP as a long-term treatment were recruited for the study. Manual titration during full polysomnography monitoring and unattended automatic titration with an automatic CPAP device (REMstar Auto) were performed. A separate cohort study of one hundred patients with OSA (AHI = 54.3 ± 18.9 events/h) was also performed by observing the efficacy of CPAP derived from manual titration. The treatment pressure derived from automatic titration (9.8 ± 2.2 cmH(2)O) was significantly higher than that derived from manual titration (7.3 ± 1.5 cmH(2)O; P < 0.001) in 51 patients. The cohort study of 100 patients showed that AHI was satisfactorily decreased after CPAP treatment using a pressure derived from manual titration (54.3 ± 18.9 events/h before treatment and 3.3 ± 1.7 events/h after treatment; P < 0.001). The results suggest that automatic titration pressure derived from REMstar Auto is usually higher than the pressure derived from manual titration. © 2013 The Authors. Respirology © 2013 Asian Pacific Society of Respirology.

Application of cause-and-effect analysis to potentiometric titration.

PubMed

Kufelnicki, A; Lis, S; Meinrath, G

2005-08-01

A first attempt has been made to interpret physicochemical data from potentiometric titration analysis in accordance with the complete measurement-uncertainty budget approach (bottom-up) of ISO and Eurachem. A cause-and-effect diagram is established and discussed. Titration data for arsenazo III are used as a basis for this discussion. The commercial software Superquad is used and applied within a computer-intensive resampling framework. The cause-and-effect diagram is applied to evaluation of seven protonation constants of arsenazo III in the pH range 2-10.7. The data interpretation is based on empirical probability distributions and their analysis by second-order correct confidence estimates. The evaluated data are applied in the calculation of a speciation diagram including uncertainty estimates using the probabilistic speciation software Ljungskile.

Investigation of the use of thermometric titrimetry for the determination of acidic substances in wine.

PubMed

Godinho, O E; Coelho, J A; Chagas, A P; Aleixo, L M

1984-03-01

The use of thermometric titrimetry in the determination of acidic substances in red wine is described. The titration curve obtained in the thermometric titration of red wine with strong base presents two inflections. The stoichiometry corresponding to the first inflection presents good agreement with the so-called "total acidity" of wine, and is proposed for its determination. The second inflection is related to the content of phenolic substances in red wine.

A wet chemical method for the estimation of carbon in uranium carbides.

PubMed

Chandramouli, V; Yadav, R B; Rao, P R

1987-09-01

A wet chemical method for the estimation of carbon in uranium carbides has been developed, based on oxidation with a saturated solution of sodium dichromate in 9M sulphuric acid, absorption of the evolved carbon dioxide in a known excess of barium hydroxide solution, and titration of the excess of barium hydroxide with standard potassium hydrogen phthalate solution. The carbon content obtained is in good agreement with that obtained by combustion and titration.

Sensitive methods for the titrimetric micro-determination of biological calcium and magnesium

PubMed Central

Beale, R. N.; Bostrom, J. O.

1963-01-01

New reagents containing high concentrations of urea are developed for micro-titration of calcium and magnesium, with ethylenediamine tetra-acetic acid (E.D.T.A.) as titrant and Corinth Ca (Plasmocorinth B) as indicator. Magnesium is determined as the difference between calcium plus magnesium and calcium. Quantitative aspects are studied, and accurate titration of untreated serum or urine is believed to be possible; precision is satisfactory. The methods are simple, robust, and suitable for routine use. Normal ranges are established for serum from blood donors of each sex. The mean serum calcium level for women is found to be lower than for men, while the mean magnesium contents are approximately the same. The latter appear to be somewhat lower than values found by flame emission spectrophotometry; in very good agreement with a mean value for plasma obtained by flame absorption spectrophotometry; and intermediate when compared with the values obtained by two other titrimetric procedures. PMID:13969919

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

PubMed

Burgot, G; Burgot, J-L

2002-10-15

Thermometric titrimetry permits titration of acido-basic compounds in water in the presence of n-octanol. n-Octanol permits the solubilization of protolytes and moreover may also displace the equilibria of the titration reactions. Hydrochlorides of highly insoluble derivatives such as phenothiazine derivatives can be titrated with satisfactory accuracy and precision by sodium hydroxide despite their high pK(a) values. Likewise barbiturate salts can be titrated by hydrochloric acid. In the case of some salts, the methodology may permit the sequential titration of the ion and counter ion. Copyright 2002 Elsevier Science B.V.

Risks and Benefits of Rapid Clozapine Titration.

PubMed

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

2016-05-18

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

Pilot study of a new device to titrate oxygen flow in hypoxic patients on long-term oxygen therapy.

PubMed

Cirio, Serena; Nava, Stefano

2011-04-01

The O(2) Flow Regulator (Dima, Bologna, Italy) is a new automated oxygen regulator that titrates the oxygen flow based on a pulse-oximetry signal to maintain a target S(pO(2)). We tested the device's safety and efficacy. We enrolled 18 subjects with chronic lung disease, exercise-induced desaturation, and on long-term oxygen therapy, in a randomized crossover study with 2 constant-work-load 15-min cycling exercise tests, starting with the patient's previously prescribed usual oxygen flow. In one test the oxygen flow was titrated manually by the respiratory therapist, and in the other test the oxygen flow was titrated by the O(2) Flow Regulator, to maintain an S(pO(2)) of 94%. We measured S(pO(2)) throughout each test, the time spent by the respiratory therapist to set the device or to manually regulate the oxygen flow, and the total number of respiratory-therapist titration interventions during the trial. There were no differences in symptoms or heart rate between the exercise tests. Compared to the respiratory-therapist-controlled tests, during the O(2) Flow Regulator tests S(pO(2)) was significantly higher (95 ± 2% vs 93 ± 3%, P = .04), significantly less time was spent below the target S(pO(2)) (171 ± 187 s vs 340 ± 220 s, P < .001), and the O(2) Flow Regulator tests required significantly less respiratory therapist time (5.6 ± 3.7 min vs 2.0 ± 0.1 min, P = .005). The O(2) Flow Regulator may be a safe and effective alternative to manual oxygen titration during exercise in hypoxic patients. It provided stable S(pO(2)) and avoided desaturations in our subjects.

Randomized Trial of Long-Acting Insulin Glargine Titration Web Tool (LTHome) Versus Enhanced Usual Therapy of Glargine Titration (INNOVATE Trial).

PubMed

Bajaj, Harpreet S; Venn, Karri; Ye, Chenglin; Aronson, Ronnie

2016-10-01

Basal insulin titration in the real world is often unsuccessful. LTHome, a web tool, applies a rules engine-based algorithm providing insulin titration advice directly to the patient. This pilot, randomized trial evaluates basal insulin glargine titration by LTHome compared to enhanced usual therapy ([EUT]-diabetes education program) over 12 weeks. Important inclusion criteria: 18-75 years, type 2 diabetes, computer literacy, and HbA1c >7.0%. Trial protocol was approved by ethics board. We randomized 139 subjects. The achievement of primary composite outcome (four out of seven fasting plasma glucose [FPG] within 5-7.2 mmol/L + mean for three consecutive FPG within 5-7.2 mmol/L + no severe hypoglycemia) was 15% in LTHome versus 41% in EUT (noninferiority not met, P-value = 0.92). Other outcomes were similar between the LTHome and EUT arms: alternate composite outcome achievement (last five FPG mean within the range of 5-7.2 mmol/L + no hypoglycemia, 47% and 51%, P = 0.73); A1c reduction (-1.0% and -1.1%, P = 0.66); proportion achieving A1c ≤7% (14% and 20%, P = 0.36); and hypoglycemia incidence (31% and 37%, P = 0.4), respectively. Patient satisfaction score improvements were greater in LTHome versus EUT (change in fear of hypoglycemia score P = 0.04 and change in diabetes distress score P = 0.04). The mean number of additional healthcare provider visits was 0.13 for LTHome and 1.22 for EUT (P < 0.01). INNOVATE trial suggests clinical utility of LTHome compared to EUT in real-life settings. Further research is needed to evaluate the efficacy and safety of automated insulin titration algorithms.

Production, concentration and titration of pseudotyped HIV-1-based lentiviral vectors.

PubMed

Kutner, Robert H; Zhang, Xian-Yang; Reiser, Jakob

2009-01-01

Over the past decade, lentiviral vectors have emerged as powerful tools for transgene delivery. The use of lentiviral vectors has become commonplace and applications in the fields of neuroscience, hematology, developmental biology, stem cell biology and transgenesis are rapidly emerging. Also, lentiviral vectors are at present being explored in the context of human clinical trials. Here we describe improved protocols to generate highly concentrated lentiviral vector pseudotypes involving different envelope glycoproteins. In this protocol, vector stocks are prepared by transient transfection using standard cell culture media or serum-free media. Such stocks are then concentrated by ultracentrifugation and/or ion exchange chromatography, or by precipitation using polyethylene glycol 6000, resulting in vector titers of up to 10(10) transducing units per milliliter and above. We also provide reliable real-time PCR protocols to titrate lentiviral vectors based on proviral DNA copies present in genomic DNA extracted from transduced cells or on vector RNA. These production/concentration methods result in high-titer vector preparations that show reduced toxicity compared with lentiviral vectors produced using standard protocols involving ultracentrifugation-based methods. The vector production and titration protocol described here can be completed within 8 d.

Signal processing with a summing operational amplifier in multicomponent potentiometric titrations.

PubMed

Parczewski, A

1987-06-01

It has been proved that application of two indicator electrodes connected to the ordinary titration apparatus through an auxiliary electronic device (a summing operational amplifier) significantly extends the scope of multicomponent potentiometric titrations in which the analytes are determined simultaneously from a single titration curve. For each analyte there is a corresponding potential jump on the titration curve. By application of the proposed auxiliary device, the sum of the electrode potentials is measured. The device also enables the relative sizes of the potential jumps at the end-points on the titration curve to be varied. The advantages of the proposed signal processing are exemplified by complexometric potentiometric titrations of Fe(III) and Cu(II) in mixtures, with a platinum electrode and a copper ion-selective electrode as the indicator electrodes.

Insights into optimal basal insulin titration in type 2 diabetes: Results of a quantitative survey.

PubMed

Berard, Lori; Bonnemaire, Mireille; Mical, Marie; Edelman, Steve

2018-02-01

Basal insulin (BI) treatment initiation and dose titration in type 2 diabetes (T2DM) are often delayed. Such "clinical inertia" results in poor glycaemic control and high risk of long-term complications. This survey aimed to determine healthcare professional (HCP) and patient attitudes to BI initiation and titration. An online survey (July-August 2015) including HCPs and patients with T2DM in the USA, France and Germany. Patients were ≥18 years old and had been on BI for 6 to 36 months, or discontinued BI within the previous 12 months. Participants comprised 386 HCPs and 318 people with T2DM. While >75% of HCPs reported discussing titration at the initiation visit, only 16% to 28% of patients remembered such discussions, many (32%-42%) were unaware of the need to titrate BI, and only 28% to 39% recalled mention of the time needed to reach glycaemic goals. Most HCPs and patients agreed that more effective support tools to assist BI initiation/titration are needed; patients indicated that provision of such tools would increase confidence in self-titration. HCPs identified fear of hypoglycaemia, failure to titrate in the absence of symptoms, and low patient motivation as important titration barriers. In contrast, patients identified weight gain, the perception that titration meant worsening disease, frustration over the time to reach HbA1c goals and fear of hypoglycaemia as major factors. A disconnect exists between HCP- and patient-perceived barriers to effective BI titration. To optimize titration, strategies should be targeted to improve HCP-patient communication, and provide support and educational tools. © 2017 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.

Insights into optimal basal insulin titration in type 2 diabetes: Results of a quantitative survey

PubMed Central

Bonnemaire, Mireille; Mical, Marie; Edelman, Steve

2017-01-01

Aims Basal insulin (BI) treatment initiation and dose titration in type 2 diabetes (T2DM) are often delayed. Such “clinical inertia” results in poor glycaemic control and high risk of long‐term complications. This survey aimed to determine healthcare professional (HCP) and patient attitudes to BI initiation and titration. Methods An online survey (July–August 2015) including HCPs and patients with T2DM in the USA, France and Germany. Patients were ≥18 years old and had been on BI for 6 to 36 months, or discontinued BI within the previous 12 months. Results Participants comprised 386 HCPs and 318 people with T2DM. While >75% of HCPs reported discussing titration at the initiation visit, only 16% to 28% of patients remembered such discussions, many (32%–42%) were unaware of the need to titrate BI, and only 28% to 39% recalled mention of the time needed to reach glycaemic goals. Most HCPs and patients agreed that more effective support tools to assist BI initiation/titration are needed; patients indicated that provision of such tools would increase confidence in self‐titration. HCPs identified fear of hypoglycaemia, failure to titrate in the absence of symptoms, and low patient motivation as important titration barriers. In contrast, patients identified weight gain, the perception that titration meant worsening disease, frustration over the time to reach HbA1c goals and fear of hypoglycaemia as major factors. Conclusion A disconnect exists between HCP‐ and patient‐perceived barriers to effective BI titration. To optimize titration, strategies should be targeted to improve HCP–patient communication, and provide support and educational tools. PMID:28719066

Multiplex titration RT-PCR: rapid determination of gene expression patterns for a large number of genes

NASA Technical Reports Server (NTRS)

Nebenfuhr, A.; Lomax, T. L.

1998-01-01

We have developed an improved method for determination of gene expression levels with RT-PCR. The procedure is rapid and does not require extensive optimization or densitometric analysis. Since the detection of individual transcripts is PCR-based, small amounts of tissue samples are sufficient for the analysis of expression patterns in large gene families. Using this method, we were able to rapidly screen nine members of the Aux/IAA family of auxin-responsive genes and identify those genes which vary in message abundance in a tissue- and light-specific manner. While not offering the accuracy of conventional semi-quantitative or competitive RT-PCR, our method allows quick screening of large numbers of genes in a wide range of RNA samples with just a thermal cycler and standard gel analysis equipment.

pH-Induced precipitation behavior of weakly basic compounds: determination of extent and duration of supersaturation using potentiometric titration and correlation to solid state properties.

PubMed

Hsieh, Yi-Ling; Ilevbare, Grace A; Van Eerdenbrugh, Bernard; Box, Karl J; Sanchez-Felix, Manuel Vincente; Taylor, Lynne S

2012-10-01

To examine the precipitation and supersaturation behavior of ten weak bases in terms of the relationship between pH-concentration-time profiles and the solid state properties of the precipitated material. Initially the compound was dissolved at low pH, followed by titration with base to induce precipitation. Upon precipitation, small aliquots of acid or base were added to induce slight subsaturation and supersaturation respectively and the resultant pH gradient was determined. The concentration of the unionized species was calculated as a function of time and pH using mass and charge balance equations. Two patterns of behavior were observed in terms of the extent and duration of supersaturation arising following an increase in pH and this behavior could be rationalized based on the crystallization tendency of the compound. For compounds that did not readily crystallize, an amorphous precipitate was formed and a prolonged duration of supersaturation was observed. For compounds that precipitated to crystalline forms, the observed supersaturation was short-lived. This study showed that supersaturation behavior has significant correlation with the solid-state properties of the precipitate and that pH-metric titration methods can be utilized to evaluate the supersaturation behavior.

Polyether precursors of molecular recognition systems based on the 9,10-anthraquinone moiety

NASA Astrophysics Data System (ADS)

Wcisło, Anna; Cirocka, Anna; Zarzeczańska, Dorota; Niedziałkowski, Paweł; Nakonieczna, Sandra; Ossowski, Tadeusz

2015-02-01

A series of novel polyether derivatives of 9,10-anthraquinone (AQ) was synthesized and characterized by means of UV-Vis spectroscopy, acid-base titration and complexometric titration. The results were compared with 1-NEt2AQ and 1-NHEtAQ - model compounds of alkylaminoanthraquinones. Acetonitrile and methanol were used as solvents for determination of spectroscopic and acid-base properties. Complexometric titrations were carried out exclusively in acetonitrile. Spectral characteristic of these compounds strongly depends on pH. Addition of acid causes the decrease of absorption intensity and in some cases also a shift of the visible range band. The weakest base is the compound (2), and the strongest - compound (1), both in methanol and acetonitrile solution. The introduction of an additional substituent in the position 8 of the anthraquinone compound increases its basicity. The presence of metal ions causes changes in intensity of absorption (decrease for compounds (2) and (3) and increase with bathochromic shift for (1) and (4)). For the determination of the coordination properties aluminum (III) ions were chosen. The highest complex stability constant with Al (III) ions is observed for compound (1), and the weakest for compound (3). The elongation of the polyether chain decreases the stability of the complex formed.

Polyether precursors of molecular recognition systems based on the 9,10-anthraquinone moiety.

PubMed

Wcisło, Anna; Cirocka, Anna; Zarzeczańska, Dorota; Niedziałkowski, Paweł; Nakonieczna, Sandra; Ossowski, Tadeusz

2015-02-25

A series of novel polyether derivatives of 9,10-anthraquinone (AQ) was synthesized and characterized by means of UV-Vis spectroscopy, acid-base titration and complexometric titration. The results were compared with 1-NEt2AQ and 1-NHEtAQ--model compounds of alkylaminoanthraquinones. Acetonitrile and methanol were used as solvents for determination of spectroscopic and acid-base properties. Complexometric titrations were carried out exclusively in acetonitrile. Spectral characteristic of these compounds strongly depends on pH. Addition of acid causes the decrease of absorption intensity and in some cases also a shift of the visible range band. The weakest base is the compound (2), and the strongest--compound (1), both in methanol and acetonitrile solution. The introduction of an additional substituent in the position 8 of the anthraquinone compound increases its basicity. The presence of metal ions causes changes in intensity of absorption (decrease for compounds (2) and (3) and increase with bathochromic shift for (1) and (4)). For the determination of the coordination properties aluminum (III) ions were chosen. The highest complex stability constant with Al (III) ions is observed for compound (1), and the weakest for compound (3). The elongation of the polyether chain decreases the stability of the complex formed. Copyright © 2014 Elsevier B.V. All rights reserved.

Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.

PubMed

In, Byunggyu; Hwang, Gi Won; Lee, Keun-Hyeung

2016-09-15

A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84×10(4)M(-1)) in aqueous buffered solutions. The detection limit (230nM, 5.98ppb) of the peptide-based sensor was much lower than the maximum allowable level (7.41μM) of aluminium ions in drinking water demanded by EPA. The binding mode of the peptide sensor with aluminium ions was characterized using ESI mass spectrometry, NMR titration, and pH titration experiments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determination of pKa values of alendronate sodium in aqueous solution by piecewise linear regression based on acid-base potentiometric titration.

PubMed

Ke, Jing; Dou, Hanfei; Zhang, Ximin; Uhagaze, Dushimabararezi Serge; Ding, Xiali; Dong, Yuming

2016-12-01

As a mono-sodium salt form of alendronic acid, alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups. The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and pH value based on acid-base potentiometric titration reaction. The distribution curves of alendronate sodium were drawn according to the determined pKa values. There were 4 dissociation constants (pKa 1 =2.43, pKa 2 =7.55, pKa 3 =10.80, pKa 4 =11.99, respectively) of alendronate sodium, and 12 existing forms, of which 4 could be ignored, existing in different pH environments.

Inactivation of the Hutchinson strain of non-A, non-B hepatitis virus by combined use of beta-propiolactone and ultraviolet irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prince, A.M.; Stephan, W.; Dichtelmueller, H.B.

1985-06-01

A beta-propiolactone/ultraviolet irradiation procedure (beta PL/UV) has been evaluated for its ability to inactivate 30,000 chimpanzee infectious doses of the Hutchinson strain of non-A, non-B (NANB) virus. The chimpanzees were inoculated with plasma to which this dose of the titrated virus had been added prior to application of the beta PL/UV process in accordance with a procedure used for licensed blood derivatives in Germany. Neither animal developed hepatitis. When subsequently challenged with the same contaminated plasma, which had not been sterilized, both animals promptly developed typical NANB hepatitis. This study extends the high (approximately 10(7)-fold) process efficiency of the betamore » PL/UV procedure previously reported for hepatitis B virus to a blood-borne NANB virus.« less

Practice parameters for the use of autotitrating continuous positive airway pressure devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome: an update for 2007. An American Academy of Sleep Medicine report.

PubMed

Morgenthaler, Timothy I; Aurora, R Nisha; Brown, Terry; Zak, Rochelle; Alessi, Cathy; Boehlecke, Brian; Chesson, Andrew L; Friedman, Leah; Kapur, Vishesh; Maganti, Rama; Owens, Judith; Pancer, Jeffrey; Swick, Todd J

2008-01-01

These practice parameters are an update of the previously published recommendations regarding the use of autotitrating positive airway pressure (APAP) devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome. Continuous positive airway pressure (CPAP) at an effective setting verified by attended polysomnography is a standard treatment for obstructive sleep apnea (OSA). APAP devices change the treatment pressure based on feedback from various patient measures such as airflow, pressure fluctuations, or measures of airway resistance. These devices may aid in the pressure titration process, address possible changes in pressure requirements throughout a given night and from night to night, aid in treatment of OSA when attended CPAP titration has not or cannot be accomplished, or improve patient comfort. A task force of the Standards of Practice Committee of the American Academy of Sleep Medicine has reviewed the literature published since the 2002 practice parameter on the use of APAP. Current recommendations follow: (1) APAP devices are not recommended to diagnose OSA; (2) patients with congestive heart failure, patients with significant lung disease such as chronic obstructive pulmonary disease; patients expected to have nocturnal arterial oxyhemoglobin desaturation due to conditions other than OSA (e.g., obesity hypoventilation syndrome); patients who do not snore (either naturally or as a result of palate surgery); and patients who have central sleep apnea syndromes are not currently candidates for APAP titration or treatment; (3) APAP devices are not currently recommended for split-night titration; (4) certain APAP devices may be used during attended titration with polysomnography to identify a single pressure for use with standard CPAP for treatment of moderate to severe OSA; (5) certain APAP devices may be initiated and used in the self-adjusting mode for unattended treatment of patients with moderate to severe OSA without significant comorbidities (CHF, COPD, central sleep apnea syndromes, or hypoventilation syndromes); (6) certain APAP devices may be used in an unattended way to determine a fixed CPAP treatment pressure for patients with moderate to severe OSA without significant comorbidities (CHF, COPD, central sleep apnea syndromes, or hypoventilation syndromes); (7) patients being treated with fixed CPAP on the basis of APAP titration or being treated with APAP must have close clinical follow-up to determine treatment effectiveness and safety; and (8) a reevaluation and, if necessary, a standard attended CPAP titration should be performed if symptoms do not resolve or the APAP treatment otherwise appears to lack efficacy.

Rapid Clozapine Titration in Patients with Treatment Refractory Schizophrenia.

PubMed

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

2016-06-01

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

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

PubMed

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

2013-11-01

Retigabine (RTG; international nonproprietary name)/ezogabine (EZG; US adopted name) is an antiepileptic drug (AED) that prolongs neuronal voltage-gated potassium-channel KCNQ2-5 (Kv 7.2-7.5) opening. This double-blind study evaluated different RTG/EZG dose-titration rates. Patients (N=73) with partial-onset seizures receiving concomitant AEDs were randomized to one of three titration groups, all of which were initiated at RTG/EZG 300mg/day divided into three equal doses. Fast-, medium-, and slow-titration groups received dose increments of 150mg/day every 2, 4, and 7 days, respectively, achieving the target dose of 1200mg/day after 13, 25, and 43 days, respectively. Safety assessments were performed throughout. Discontinuation rates due to treatment-emergent adverse events (TEAEs) were numerically higher in the fast- (10/23) and medium- (7/22) titration groups than in the slow-titration group (3/23) but statistical significance was achieved only for the high-titration group compared with the low-titration group (p=0.024). Stratified analysis, with concomitant AEDs divided into enzyme inducers (carbamazepine, phenytoin, oxcarbazepine) or noninducers, showed that the risk of discontinuation due primarily to TEAEs was significantly higher in the fast- (p=0.010) but not in the medium-titration group (p=0.078) when compared with the slow-titration group. Overall, the slow-titration rate appeared to be best tolerated and was used in further efficacy and safety studies with RTG/EZG. Copyright © 2013 Elsevier B.V. All rights reserved.

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Potassium Ferricyanide Titration..., App. A Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The potassium... buffered sulfide solution is titrated with standard potassium ferricyanide solution in the presence of a...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Potassium Ferricyanide Titration..., App. A Appendix A to Part 425—Potassium Ferricyanide Titration Method Source The potassium... buffered sulfide solution is titrated with standard potassium ferricyanide solution in the presence of a...

A new method for determining the acid number of biodiesel based on coulometric titration.

PubMed

Barbieri Gonzaga, Fabiano; Pereira Sobral, Sidney

2012-08-15

A new method is proposed for determining the acid number (AN) of biodiesel using coulometric titration with potentiometric detection, basically employing a potentiostat/galvanostat and an electrochemical cell containing a platinum electrode, a silver electrode, and a combination pH electrode. The method involves a sequential application of a constant current between the platinum (cathode) and silver (anode) electrodes, followed by measuring the potential of the combination pH electrode, using an isopropanol/water mixture as solvent and LiCl as the supporting electrolyte. A preliminary evaluation of the new method, using acetic acid for doping a biodiesel sample, showed an average recovery of 100.1%. Compared to a volumetric titration-based method for determining the AN of several biodiesel samples (ranging from about 0.18 to 0.95 mg g(-1)), the new method produced statistically similar results with better repeatability. Compared to other works reported in the literature, the new method presented an average repeatability up to 3.2 times better and employed a sample size up to 20 times smaller. Copyright © 2012 Elsevier B.V. All rights reserved.

Tunable Control of an Escherichia coli Expression System for the Overproduction of Membrane Proteins by Titrated Expression of a Mutant lac Repressor.

PubMed

Kim, Seong Keun; Lee, Dae-Hee; Kim, Oh Cheol; Kim, Jihyun F; Yoon, Sung Ho

2017-09-15

Most inducible expression systems suffer from growth defects, leaky basal induction, and inhomogeneous expression levels within a host cell population. These difficulties are most prominent with the overproduction of membrane proteins that are toxic to host cells. Here, we developed an Escherichia coli inducible expression system for membrane protein production based on titrated expression of a mutant lac repressor (mLacI). Performance of the mLacI inducible system was evaluated in conjunction with commonly used lac operator-based expression vectors using a T7 or tac promoter. Remarkably, expression of a target gene can be titrated by the dose-dependent addition of l-rhamnose, and the expression levels were homogeneous in the cell population. The developed system was successfully applied to overexpress three membrane proteins that were otherwise difficult to produce in E. coli. This gene expression control system can be easily applied to a broad range of existing protein expression systems and should be useful in constructing genetic circuits that require precise output signals.

Acid-base buffering of soils in transitional and transitional-accumulative positions of undisturbed southern-taiga landscapes

NASA Astrophysics Data System (ADS)

Rusakova, E. S.; Ishkova, I. V.; Tolpeshta, I. I.; Sokolova, T. A.

2012-05-01

The method of continuous potentiometric titration (CPT) of soil water suspensions was used to evaluate the acid-base buffering of samples from the major genetic horizons of podzolic soils on a slope and soddy gley soils on the adjacent floodplain of a rivulet. In the soils of the slope, the buffering to acid upon titration from the pH of the initial titration point (ITP) to pH 3 in all the horizons was 1.5-2.0 times lower than that in the podzolic soils of the leveled interfluve, which could be due to the active leaching of exchangeable bases and oxalate-soluble aluminum and iron compounds with the later soil flows. In the soddy gley soils, the buffering to acid in the mineral horizons was 2-10 times higher than that in the podzolic soils. A direct dependence of the soil buffering to acid on the total content of exchangeable bases and on the content of oxalate-soluble aluminum compounds was found. A direct dependence of the buffering to basic upon titration from the ITP to pH 10 on the contents of the oxalate-soluble aluminum and organic matter was observed in the mineral horizons of all the studied soils. The soil treatment with Tamm's reagent resulted in the decrease of the buffering to acid in the soddy gley soils of the floodplain, as well as in the decrease of the buffering to basic in the soils on the slopes and in the soddy gley soils. It was also found that the redistribution of the mobile aluminum compounds between the eluvial, transitional, and transitional-accumulative positions in the undisturbed southern taiga landscapes leads to significant spatial differentiation of the acid-base buffering of the mineral soil horizons with a considerable increase in the buffer capacity of the soils within the transitional-accumulative terrain positions.

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

PubMed

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

2015-03-13

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. 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. 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. 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. 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. Clinicaltrials.gov NCT01879579; http://clinicaltrials.gov/ct2/show/NCT01879579 (Archived by WebCite at http://www.webcitation.org/6WUEgjZUO).

Impact of systolic blood pressure on the safety and tolerability of initiating and up-titrating sacubitril/valsartan in patients with heart failure and reduced ejection fraction: insights from the TITRATION study.

PubMed

Senni, Michele; McMurray, John J V; Wachter, Rolf; McIntyre, Hugh F; Anand, Inder S; Duino, Vincenzo; Sarkar, Arnab; Shi, Victor; Charney, Alan

2018-03-01

The TITRATION trial investigated two strategies to initiate and up-titrate sacubitril/valsartan (LCZ696) to the same target dose, over a condensed (3-week) or conservative (6-week) period, in patients with heart failure with reduced ejection fraction (HFrEF) and systolic blood pressure (SBP) of ≥100 mmHg. This post hoc analysis examined the relationship between baseline SBP at screening and achievement of the target dose of sacubitril/valsartan of 97 mg/103 mg (also termed 'LCZ696 200 mg') twice per day during the study. Patients (n = 498) were categorized in four groups based on SBP at screening: 100-110 mmHg (n = 70); 111-120 mmHg (n = 93); 121-139 mmHg (n = 168) and ≥140 mmHg (n = 167). Overall, 72.7%, 76.1%, 85.6% and 82.9%, respectively, of patients in these SBP categories achieved and maintained the target dose of sacubitril/valsartan without down-titration/dose interruption over 12 weeks ('treatment success'). Compared with patients with SBP of 100-110 mmHg, rates of treatment success among patients in the higher SBP groups [111-120 mmHg (P = 0.96); 121-139 mmHg (P = 0.06) and ≥140 mmHg (P = 0.25)] did not differ significantly. A higher percentage of patients with lower SBP (100-110 mmHg) achieved treatment success with gradual up-titration (6 weeks) (∼80%) than with rapid up-titration (∼69%). Similar findings were observed with regard to 'tolerability success' (maintenance of the target dose for at least the final 2 weeks prior to study completion). Hypotension occurred more frequently in patients with lower SBP. The majority of patients (>80%) with SBP of ≥100 mmHg achieved and maintained the target dose of sacubitril/valsartan if the treatment was titrated gradually. These findings suggest that low SBP should not prevent clinicians from considering the initiation of sacubitril/valsartan. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

Highly selective electrode for potentiometric analysis of methadone in biological fluids and pharmaceutical formulations.

PubMed

Ardeshiri, Moslem; Jalali, Fahimeh

2016-06-01

In order to develop a fast and simple procedure for methadone analysis in biological fluids, a graphite paste electrode (GPE) was modified with the ion-pair of methadone-phosphotungstic acid, and multiwalled carbon nanotubes (MWCNTs). Optimized composition of the electrode with respect to graphite powder:paraffin oil:MWCNTs:ion pair, was 58:30:8:4 (w/w%). The electrode showed a near-Nernstian slope of 58.9 ± 0.3 mV/decade for methadone in a wide linear range of 1.0 × 10(-8)-4.6 × 10(-3)M, with a detection limit of 1.0 × 10(-8)M. The electrode response was independent of pH in the range of 5-11, with a fast response time (~4s) at 25 °C. The sensor showed high selectivity and was successfully applied to the determination of sub-micromolar concentrations of methadone in human blood serum and urine samples, with recoveries in the range of 95-99.8%. The average recovery of methadone from tablets (5 mg/tablet) by using the proposed method was 98%. The life time of the modified electrode was more than 5 months, due to the characteristic of GPE which can be cut off and fresh electrode surface be available. A titration procedure was performed for methadone analysis by using phosphotungstic acid, as titrating agent, which showed an accurate end point and 1:1 stoichiometry for the ion-pair formed (methadone:phosphotungstic acid). The simple and rapid procedure as well as excellent detection limit and selectivity are some of the advantages of the proposed sensor for methadone. Copyright © 2016 Elsevier B.V. All rights reserved.

Predictors of Arterial Blood Pressure Control During Deliberate Hypotension with Sodium Nitroprusside in Children

PubMed Central

Spielberg, David R; Barrett, Jeffrey S; Hammer, Gregory B; Drover, David R; Reece, Tammy; Cohane, Carol A; Schulman, Scott R

2014-01-01

Background Sodium nitroprusside (SNP) is used to decrease arterial blood pressure (BP) during certain surgical procedures. There are limited data regarding efficacy of BP control with SNP. There are no data on patient and clinician factors that affect BP control. We evaluated the dose-response relationship of SNP in infants and children undergoing major surgery and performed a quantitative assessment of BP control. Methods One hundred fifty-three subjects at 7 sites received a blinded infusion followed by open-label SNP during operative procedures requiring controlled hypotension. SNP was administered by continuous infusion and titrated to maintain BP control (mean arterial BP [MAP] within ±10% of clinician-defined target). BP was recorded using an arterial catheter. Statistical Process Control methodology was used to quantify BP control. A multivariable model assessed the effects of patient and procedural factors. Results BP was controlled an average 45.4% (SD 23.9%, 95% CI 41.5%-49.18%) of the time. Larger changes in infusion rate were associated with worse BP control (7.99% less control for 1 mcg•kg−•min− increase in average titration size, p=0.0009). A larger difference between a patient's baseline and target MAP predicted worse BP control (0.93% worse control per 1 mmHg increase in MAP difference, p=0.0013). Both effects persisted in multivariable models. Conclusions : SNP was effective in reducing BP. However, BP was within the target range less than half of the time. No clinician or patient factors were predictive of BP control, although two inverse relationships were identified. These relationships require additional study and may be best coupled with exposure-response modeling to propose improved dosing strategies when using SNP for controlled hypotension in the pediatric population. PMID:25099924

Predictors of arterial blood pressure control during deliberate hypotension with sodium nitroprusside in children.

PubMed

Spielberg, David R; Barrett, Jeffrey S; Hammer, Gregory B; Drover, David R; Reece, Tammy; Cohane, Carol A; Schulman, Scott R

2014-10-01

Sodium nitroprusside (SNP) is used to decrease arterial blood pressure (BP) during certain surgical procedures. There are limited data regarding efficacy of BP control with SNP. There are no data on patient and clinician factors that affect BP control. We evaluated the dose-response relationship of SNP in infants and children undergoing major surgery and performed a quantitative assessment of BP control. One hundred fifty-three subjects at 7 sites received a blinded infusion followed by open-label SNP during operative procedures requiring controlled hypotension. SNP was administered by continuous infusion and titrated to maintain BP control (mean arterial BP [MAP] within ±10% of clinician-defined target). BP was recorded using an arterial catheter. Statistical process control methodology was used to quantify BP control. A multivariable model assessed the effects of patient and procedural factors. BP was controlled an average 45.4% (SD 23.9%; 95% CI, 41.5%-49.18%) of the time. Larger changes in infusion rate were associated with worse BP control (7.99% less control for 1 μg·kg·min increase in average titration size, P = 0.0009). A larger difference between a patient's baseline and target MAP predicted worse BP control (0.93% worse control per 1-mm Hg increase in MAP difference, P = 0.0013). Both effects persisted in multivariable models. SNP was effective in reducing BP. However, BP was within the target range less than half of the time. No clinician or patient factors were predictive of BP control, although 2 inverse relationships were identified. These relationships require additional study and may be best coupled with exposure-response modeling to propose improved dosing strategies when using SNP for controlled hypotension in the pediatric population.

Inquiry-based Laboratory Activities on Drugs Analysis for High School Chemistry Learning

NASA Astrophysics Data System (ADS)

Rahmawati, I.; Sholichin, H.; Arifin, M.

2017-09-01

Laboratory activity is an important part of chemistry learning, but cookbook instructions is still commonly used. However, the activity with that way do not improve students thinking skill, especially students creativity. This study aims to improve high school students creativity through inquiry-based laboratory on drugs analysis activity. Acid-base titration is used to be method for drugs analysis involving a color changing indicator. The following tools were used to assess the activity achievement: creative thinking test on acid base titration, creative attitude and action observation sheets, questionnaire of inquiry-based lab activities, and interviews. The results showed that the inquiry-based laboratory activity improving students creative thinking, creative attitude and creative action. The students reacted positively to this teaching strategy as demonstrated by results from questionnaire responses and interviews. This result is expected to help teachers to overcome the shortcomings in other laboratory learning.

Determination of total fluoride in HF/HNO3/H2SiF6 etch solutions by new potentiometric titration methods.

PubMed

Weinreich, Wenke; Acker, Jörg; Gräber, Iris

2007-03-30

In the photovoltaic industry the etching of silicon in HF/HNO(3) solutions is a decisive process for cleaning wafer surfaces or to produce certain surface morphologies like polishing or texturization. With regard to cost efficiency, a maximal utilisation of etch baths in combination with highest quality and accuracy is strived. To provide an etch bath control realised by a replenishment with concentrated acids the main constituents of these HF/HNO(3) etch solutions including the reaction product H(2)SiF(6) have to be analysed. Two new methods for the determination of the total fluoride content in an acidic etch solution based on the precipitation titration with La(NO(3))(3) are presented within this paper. The first method bases on the proper choice of the reaction conditions, since free fluoride ions have to be liberated from HF and H(2)SiF(6) at the same time to be detected by a fluoride ion-selective electrode (F-ISE). Therefore, the sample is adjusted to a pH of 8 for total cleavage of the SiF(6)(2-) anion and titrated in absence of buffers. In a second method, the titration with La(NO(3))(3) is followed by a change of the pH-value using a HF resistant glass-electrode. Both methods provide consistent values, whereas the analysis is fast and accurate, and thus, applicable for industrial process control.

Acid-base titration of melanocortin peptides: evidence of Trp rotational conformers interconversion.

PubMed

Fernandez, Roberto M; Vieira, Renata F F; Nakaie, Clóvis R; Lamy, M Teresa; Ito, Amando S

2005-01-01

Tryptophantime-resolved fluorescence was used to monitor acid-base titration properties of alpha-melanocyte stimulating hormone (alpha-MSH) and the biologically more potent analog [Nle4, D-Phe7]alpha -MSH (NDP-MSH), labeled or not with the paramagnetic amino acid probe 2,2,6,6-tetramthylpiperidine-N-oxyl-4-amino-4-carboxylic acid (Toac). Global analysis of fluorescence decay profiles measured in the pH range between 2.0 and 11.0 showed that, for each peptide, the data could be well fitted to three lifetimes whose values remained constant. The less populated short lifetime component changed little with pH and was ascribed to Trp g+ chi1 rotamer, in which electron transfer deactivation predominates over fluorescence. The long and intermediate lifetime preexponential factors interconverted along that pH interval and the result was interpreted as due to interconversion between Trp g- and trans chi1 rotamers, driven by conformational changes promoted by modifications in the ionization state of side-chain residues. The differences in the extent of interconversion in alpha-MSH and NDP-MSH are indicative of structural differences between the peptides, while titration curves suggest structural similarities between each peptide and its Toac-labeled species, in aqueous solution. Though less sensitive than fluorescence, the Toac electron spin resonance (ESR) isotropic hyperfine splitting parameter can also monitor the titration of side-chain residues located relatively far from the probe. Copyright (c) 2005 Wiley Periodicals, Inc.

A rapid Q-PCR titration protocol for adenovirus and helper-dependent adenovirus vectors that produces biologically relevant results

PubMed Central

Gallaher, Sean D.; Berk, Arnold J.

2013-01-01

Adenoviruses are employed in the study of cellular processes and as expression vectors used in gene therapy. The success and reproducibility of these studies is dependent in part on having accurate and meaningful titers of replication competent and helper-dependent adenovirus stocks, which is problematic due to the use of varied and divergent titration protocols. Physical titration methods, which quantify the total number of viral particles, are used by many, but are poor at estimating activity. Biological titration methods, such as plaque assays, are more biologically relevant, but are time consuming and not applicable to helper-dependent gene therapy vectors. To address this, a protocol was developed called “infectious genome titration” in which viral DNA is isolated from the nuclei of cells ~3 h post-infection, and then quantified by Q-PCR. This approach ensures that only biologically active virions are counted as part of the titer determination. This approach is rapid, robust, sensitive, reproducible, and applicable to all forms of adenovirus. Unlike other Q-PCR-based methods, titers determined by this protocol are well correlated with biological activity. PMID:23624118

Acidic beverages increase the risk of in vitro tooth erosion.

PubMed

Ehlen, Leslie A; Marshall, Teresa A; Qian, Fang; Wefel, James S; Warren, John J

2008-05-01

Acidic beverages are thought to increase the potential for dental erosion. We report pH and titratable acidities (ie, quantity of base required to bring a solution to neutral pH) of beverages popular in the United States and lesion depths in enamel and root surfaces after beverage exposure, and we describe associations among pH, titratable acidity, and both enamel and root erosive lesion depths. The pH of 100% juices, regular sodas, diet sodas, and sports drinks upon opening and the titratable acidity both upon opening and after 60 minutes of stirring were measured. Enamel and root surfaces of healthy permanent molars and premolars were exposed to individual beverages (4 enamel and 4 root surfaces per beverage) for 25 hours, and erosion was measured. Statistical analyses included 2-sample t tests, analyses of variance with post hoc Tukey studentized range test; and Spearman rank correlation coefficients. All beverages were acidic; the titratable acidity of energy drinks was greater than that of regular and diet sodas that were greater than that of 100% juices and sports drinks (P < .05). Enamel lesion depths after beverage exposures were greatest for Gatorade, followed by those for Red Bull and Coke that were greater than those for Diet Coke and 100% apple juice (P < .05). Root lesion depths were greatest for Gatorade, followed by Red Bull, Coke, 100% apple juice, and Diet Coke (P < .05). Lesion depths were not associated with pH or titratable acidity. Beverages popular in the United States can produce dental erosion.

Simple and Automated Coulometric Titration of Acid Using Nonisolated Electrodes

ERIC Educational Resources Information Center

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

2011-01-01

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

Natural monocrystalline pyrite as a sensor in non-aqueous solution Part I: Potentiometric titration of weak acids in, N,N-dimethylformamide, methylpyrrolidone and pyridine.

PubMed

Mihajlović, Lj V; Mihajlović, R P; Antonijević, M M; Vukanović, B V

2004-11-15

The possibility of applying natural monocrystaline pyrite as a sensor for the potentiometric titration of weak acids in N,N-dimethylformamide, methylpyrrolidone and pyridine was investigated. The potential of this electrode in N,N-dimethylformamide, methylpyrrolidone and pyridine exhibits a sub-Nernst dependence. In N,N-dimethylformamide the slope (mV/pH) is 39.0 and in methylpyrrolidone it is 45.0. The potential jumps at the titration end-point obtained in the titration of weak acids are higher than those obtained by the application of a glass electrode as the indicator electrode The potential in the course of the titration and at the titration end-point (TEP) are rapidly established. Sodium methylate, potassium hydroxide and tetrabutylammonium hydroxide (TBAH) proved to be very suitable titrating agents for these titrations. The results obtained in the determination of the investigated weak acids deviate by 0.1-0.35% with respect to those obtained by using a glass electrode as the indicator electrode.

Utility of Left Atrial Expansion Index and Stroke Volume in Management of Chronic Systolic Heart Failure.

PubMed

Hsiao, Shih-Hung; Lin, Shih-Kai; Chiou, Yi-Ran; Cheng, Chin-Chang; Hwang, Hwong-Ru; Chiou, Kuan-Rau

2018-06-01

Titration of evidence-based medications, important for treating heart failure (HF), is often underdosed by symptom-guided treatment. The aim of this study was to investigate, using echocardiographic parameters, stroke volume and left ventricular (LV) filling pressure to guide up-titration of medications, increasing prognostic benefits. A total of 765 patients with chronic HF and severely reduced LV ejection fractions (<35%), referred from 2008 to 2016, were prospectively studied. Echocardiographic guidance was performed in 149 patients. LV filling pressure was assessed by left atrial expansion index, and stroke volume was estimated from diameter and time-velocity integral in the LV outflow tract. Up-titration of evidence-based medications and adjustment for side effects or worsening clinical conditions according to those parameters were performed. Propensity score matching was used to match pairs of patients with (n = 110) or without (n = 110) echocardiographic guidance. End points were 4-year frequencies of HF hospitalization and all-cause mortality. During a mean follow-up time of 4.1 years, rates of adverse events were 58 (52.7%) with no echocardiographic guidance and 36 (32.7%) with echocardiographic guidance (P < .0001). Echocardiography provided effective guidance to reduce prescribing frequency and dose of diuretics and to promote evidence-based medication prescription. It reduced HF rehospitalization and all-cause mortality. By multivariate analysis, prognostic improvement was associated with up-titration of medications with echocardiographic guidance. There was a statistically significant difference in long-term prognosis between propensity score-matched pairs of patients with chronic severe HF with and without echocardiographic guidance. These findings need further validation in large prospective clinical trials. Copyright © 2018 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Corrosion Control Through a Better Understanding of the Metallic Substrate/Organic Coating/Interface.

DTIC Science & Technology

1981-11-01

and the cyclohexane over molecular sieves, -79- pm NO pAalB hION fl i4a and then measuring the ppm of water in the cyclohexane using the Karl Fischer ... potentiometric titration using a method outlined by Bell [J. Polymer Sci. 8, 417-36 (1970)]. The procedure for epoxy groups involves the re- action with...with time, earliest stages of coating delamination, and secondary processes that occur was obtained by time lapse photography. Electrical methods are

Potentiometric titration of metal ions in ethanol.

PubMed

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

2006-09-18

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.

Rapid Inpatient Titration of Intravenous Treprostinil for Pulmonary Arterial Hypertension: Safe and Tolerable.

PubMed

El-Kersh, Karim; Ruf, Kathryn M; Smith, J Shaun

There is no standard protocol for intravenous treprostinil dose escalation. In most cases, slow up-titration is performed in the outpatient setting. However, rapid up-titration in an inpatient setting is an alternative that provides opportunity for aggressive treatment of common side effects experienced during dose escalation. In this study, we describe our experience with inpatient rapid up-titration of intravenous treprostinil. This was a single-center, retrospective study in which we reviewed the data of subjects with pulmonary arterial hypertension treated at our center who underwent inpatient rapid up-titration of intravenous treprostinil. Our treprostinil dose escalation protocol included initiation at 2 ng·kg·min with subsequent up-titration by 1 ng·kg·min every 6 to 8 hours as tolerated by side effects. A total of 16 subjects were identified. Thirteen subjects were treprostinil naive (naive group), and 3 subjects were receiving subcutaneous treprostinil but were hospitalized for further intravenous up-titration of treprostinil dose (nonnaive group). In the naive group, the median maximum dose achieved was 20 ng·kg·min with an interquartile range (IQR) of 20-23 ng·kg·min. The median up-titration interval was 6 days (IQR: 4-9). In the nonnaive group, the median maximum dose achieved was 20 ng·kg·min (range: 17-30). The median up-titration interval was 8.5 days (range: 1.5-11). Overall, the median maximum dose achieved was 20 ng·kg·min (IQR: 20-23.5), and the median up-titration interval was 6 days (IQR: 4.6-9.25), with no reported significant adverse hemodynamic events. In patients with pulmonary arterial hypertension, rapid inpatient titration of intravenous treprostinil is safe and tolerable.

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

PubMed Central

Legangneux, Eric; Gardin, Anne; Johns, Donald

2013-01-01

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

DIFFERENTIAL THERMOMETRIC TITRATIONS AND THE DETERMINATION OF HEATS OF REACTION,

DTIC Science & Technology

TITRATION , THERMISTORS), (*HEAT OF REACTION, TITRATION ), SILVER COMPOUNDS, NITRATES, AMMONIA, PYRIDINES, ETHYLENEDIAMINE, AMINES, ALCOHOLS, BUTANOLS, PROPANOLS, SODIUM COMPOUNDS, HYDROXIDES, TEST METHODS

Ultrasonic and densimetric titration applied for acid-base reactions.

PubMed

Burakowski, Andrzej; Gliński, Jacek

2014-01-01

Classical acoustic acid-base titration was monitored using sound speed and density measurements. Plots of these parameters, as well as of the adiabatic compressibility coefficient calculated from them, exhibit changes with the volume of added titrant. Compressibility changes can be explained and quantitatively predicted theoretically in terms of Pasynski theory of non-compressible hydrates combined with that of the additivity of the hydration numbers with the amount and type of ions and molecules present in solution. It also seems that this development could be applied in chemical engineering for monitoring the course of chemical processes, since the applied experimental methods can be carried out almost independently on the medium under test (harmful, aggressive, etc.).

Surface acid-base properties and hydration/dehydration mechanisms of aluminum (hydr)oxides.

PubMed

Yang, Xiaofang; Sun, Zhongxi; Wang, Dongsheng; Forsling, Willis

2007-04-15

In this paper, surface physiochemical properties of three typical aluminas, gamma-Al(OH)3, gamma-Al2O3, and alpha-Al2O3, were investigated by means of XRD, SEM, TEM, BET surface area, TG/DTA, and potentiometric titration techniques. Based on the titration data, surface protonation and deprotonation constants were determined using the constant capacitance model (CCM). The emphasis of this research was laid on the comparison of the crystal structure, surface hydration/dehydration and acid-base properties of these three typical alumina minerals. The calculation results revealed that the surface acidity of the aluminas is in the order of alpha-Al2O3>gamma-Al(OH)3>gamma-Al2O3 after being hydrated for 1 h. The correlation between the hydration/dehydration mechanisms of alumina and its acid/base properties is discussed.

The SimpleMix study with biphasic insulin aspart 30: a randomized controlled trial investigating patient-driven titration versus investigator-driven titration.

PubMed

Gao, Yan; Luquez, Cecilia; Lynggaard, Helle; Andersen, Henning; Saboo, Banshi

2014-12-01

The study aimed to confirm the efficacy, through non-inferiority, of patient-driven versus investigator-driven titration of biphasic insulin aspart 30 (BIAsp 30) in terms of glycemic control assessed by HbA1c change. SimpleMix was a 20 week, open-label, randomized, two-armed, parallel-group, multicenter study in five countries (Argentina, China, India, Poland, and the UK). Patients with type 2 diabetes were randomized into either patient-driven or investigator-driven BIAsp 30 titration groups. Non-inferiority of patient-driven vs. investigator-driven titration based on change in HbA1c from baseline to week 20 could not be demonstrated. Mean (SE) estimated change from baseline to week 20 was -0.72 (0.08)% in the patient-driven group and -0.97 (0.08)% in the investigator-driven group; estimated difference 0.25% (95% CI: 0.04; 0.46). Estimated mean change (SE) in fasting plasma glucose from baseline to week 20 was similar between groups: -0.94 (0.21) mmol/L for patient-driven and -1.07 (0.22) mmol/L for investigator-driven (difference non-significant). Both treatment arms were well tolerated, and hypoglycemic episode rates were similar between groups, with a rate ratio of 0.77 (95% CI: 0.54; 1.09; p = 0.143) for all hypoglycemic episodes and 0.78 (95% CI: 0.42; 1.43; p = 0.417) for nocturnal hypoglycemic episodes. Non-inferiority of patient-driven versus investigator-driven titration with regard to change from baseline to end-of-treatment HbA1c could not be confirmed. It is possible that a clinic visit 12 weeks after intensification of treatment with BIAsp 30 in patients with type 2 diabetes inadequately treated with basal insulin may benefit patient-driven titration of BIAsp 30. A limitation of the study was the relatively small number of patients recruited in each country, which does not allow country-specific analyses to be performed. Overall, treatment with BIAsp 30 was well tolerated in both treatment groups.

Determination of carbonate carbon in geological materials by coulometric titration

USGS Publications Warehouse

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

1985-01-01

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

Simple Modification of Karl-Fischer Titration Method for Determination of Water Content in Colored Samples

PubMed Central

Tavčar, Eva; Turk, Erika; Kreft, Samo

2012-01-01

The most commonly used technique for water content determination is Karl-Fischer titration with electrometric detection, requiring specialized equipment. When appropriate equipment is not available, the method can be performed through visual detection of a titration endpoint, which does not enable an analysis of colored samples. Here, we developed a method with spectrophotometric detection of a titration endpoint, appropriate for moisture determination of colored samples. The reaction takes place in a sealed 4 ml cuvette. Detection is performed at 520 nm. Titration endpoint is determined from the graph of absorbance plotted against titration volume. The method has appropriate reproducibility (RSD = 4.3%), accuracy, and linearity (R 2 = 0.997). PMID:22567558

Practice Parameters for the Use of Autotitrating Continuous Positive Airway Pressure Devices for Titrating Pressures and Treating Adult Patients with Obstructive Sleep Apnea Syndrome: An Update for 2007

PubMed Central

Morgenthaler, Timothy I.; Aurora, R. Nisha; Brown, Terry; Zak, Rochelle; Alessi, Cathy; Boehlecke, Brian; Chesson, Andrew L.; Friedman, Leah; Kapur, Vishesh; Maganti, Rama; Owens, Judith; Pancer, Jeffrey; Swick, Todd J.

2008-01-01

These practice parameters are an update of the previously published recommendations regarding the use of autotitrating positive airway pressure (APAP) devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome. Continuous positive airway pressure (CPAP) at an effective setting verified by attended polysomnography is a standard treatment for obstructive sleep apnea (OSA). APAP devices change the treatment pressure based on feedback from various patient measures such as airflow, pressure fluctuations, or measures of airway resistance. These devices may aid in the pressure titration process, address possible changes in pressure requirements throughout a given night and from night to night, aid in treatment of OSA when attended CPAP titration has not or cannot be accomplished, or improve patient comfort. A task force of the Standards of Practice Committee of the American Academy of Sleep Medicine has reviewed the literature published since the 2002 practice parameter on the use of APAP. Current recommendations follow: (1) APAP devices are not recommended to diagnose OSA; (2) patients with congestive heart failure, patients with significant lung disease such as chronic obstructive pulmonary disease; patients expected to have nocturnal arterial oxyhemoglobin desaturation due to conditions other than OSA (e.g., obesity hypoventilation syndrome); patients who do not snore (either naturally or as a result of palate surgery); and patients who have central sleep apnea syndromes are not currently candidates for APAP titration or treatment; (3) APAP devices are not currently recommended for split-night titration; (4) certain APAP devices may be used during attended titration with polysomnography to identify a single pressure for use with standard CPAP for treatment of moderate to severe OSA; (5) certain APAP devices may be initiated and used in the self-adjusting mode for unattended treatment of patients with moderate to severe OSA without significant comorbidities (CHF, COPD, central sleep apnea syndromes, or hypoventilation syndromes); (6) certain APAP devices may be used in an unattended way to determine a fixed CPAP treatment pressure for patients with moderate to severe OSA without significant comorbidities (CHF, COPD, central sleep apnea syndromes, or hypoventilation syndromes); (7) patients being treated with fixed CPAP on the basis of APAP titration or being treated with APAP must have close clinical follow-up to determine treatment effectiveness and safety; and (8) a reevaluation and, if necessary, a standard attended CPAP titration should be performed if symptoms do not resolve or the APAP treatment otherwise appears to lack efficacy. Citation: Morgenthaler TI; Aurora RN; Brown T; Zak R; Alessi C; Boehlecke B; Chesson AL; Friedman L; Kapur V; Maganti R; Owens J; Pancer J; Swick TJ; Standards of Practice Committee of the AASM. Practice parameters for the use of autotitrating continuous positive airway pressure devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome: An update for 2007. SLEEP 2008;31(1):141-147. PMID:18220088

Adjustable tongue advancement for obstructive sleep apnea: a pilot study.

PubMed

Hamans, Evert; Boudewyns, An; Stuck, Boris A; Baisch, Alexander; Willemen, Marc; Verbraecken, Johan; Van de Heyning, Paul

2008-11-01

Surgical treatment of obstructive sleep apnea (OSA) caused by hypopharyngeal collapse of the upper airway can be considered in patients who are intolerant to continuous positive airway pressure (CPAP). The present procedures addressing the hypopharynx are invasive and have substantial morbidity and limited efficacy. Ten patients (mean age, 44 years) with moderate to severe OSA, ie, an apnea-hypopnea index (AHI) between 15 and 50, with CPAP intolerance were included in a prospective, nonrandomized, multicenter study to evaluate the feasibility, safety, and efficacy of a novel tongue advancement procedure. The procedure consists of the implantation of a tissue anchor in the tongue base and an adjustment spool at the mandible. Titration of this tissue anchor results in advancement of the tongue and a patent upper airway. The mean AHI decreased from 22.8 at baseline to 11.8 at the 6-month follow-up (p = 0.007). The Epworth Sleepiness Scale score decreased from 11.4 at baseline to 7.7 at the 6-month follow-up (p = 0.094), and the snoring score decreased from 7.5 at baseline to 3.9 at the 6-month follow-up (p = 0.005). Four technical adverse events were noted, and 1 clinical adverse event occurred. Adjustable tongue advancement is a feasible and relatively safe way to reduce the AHI and snoring in selected patients with moderate to severe OSA and CPAP intolerance. Technical improvements and refinements to the procedure are ongoing.

Development of a potentiometric EDTA method for determination of molybdenum. Use of the analysis for molybdenite concentrates

NASA Technical Reports Server (NTRS)

Khristova, R.; Vanmen, M.

1986-01-01

Based on considerations of principles and experimental data, the interference of sulfate ions in poteniometric titration of EDTA with FeCl3 was confirmed. The method of back complexometric titration of molybdenum of Nonova and Gasheva was improved by replacing hydrazine sulfate with hydrazine hydrochloride for reduction of Mo(VI) to Mo(V). The method can be used for one to tenths of mg of molybdenum with 0.04 mg standard deviation. The specific method of determination of molybdenum in molybdenite concentrates is presented.

Passive haemagglutination test for antibodies against rabies virus*

PubMed Central

Gough, P. M.; Dierks, R. E.

1971-01-01

All the procedures now available for the measurement of rabies virus antibodies in serum have certain disadvantages. The serum neutralization test (SN), whether carried out by assay in mice or by the plaque-reduction technique, requires several days before the titrations are completed, necessitates special facilities for keeping large numbers of animals and tissue-culture plates, and is relatively expensive. A complement-fixation test is very insensitive, giving low titres in comparison with SN tests, and a haemagglutination-inhibition procedure is complicated by the presence of nonspecific reactions. A rabies passive haemagglutination technique (RPHA), developed to overcome many of these problems, is described. Titres obtained with human sera by the RPHA procedure correlated well with those obtained by SN tests. Both IgG and IgM classes of antibodies were measured by the RPHA procedure; however, it appeared to be more sensitive for detecting IgM than was the SN test and, therefore, gave higher titres for this class of immunoglobulins. PMID:5317009

Implementation of a pharmacist-managed heart failure medication titration clinic.

PubMed

Martinez, Amanda S; Saef, Jerold; Paszczuk, Anna; Bhatt-Chugani, Hetal

2013-06-15

The development, implementation, and initial results of a pharmacist-managed heart failure (HF) medication titration clinic are described. In a quality-improvement initiative at a Veterans Affairs health care system, clinical pharmacists were incorporated into the hospital system's interprofessional outpatient HF clinic. In addition, a separate pharmacist-managed HF medication titration clinic was established, in which pharmacists were granted an advanced scope of practice and prescribing privileges, enabling them to initiate and adjust medication dosages under specific protocols jointly established by cardiology and pharmacy staff. Pharmacists involved in the titration clinic tracked patients' daily body weight, vital signs, and volume status using telephone-monitoring technology and via patient interviews. A retrospective chart review comparing achievement of target doses of angiotensin-converting enzyme inhibitor (ACEI), angiotensin-receptor blocker (ARB), and β-blocker therapies in a group of patients (n = 28) whose dosage titrations were carried out by nurses or physicians prior to implementation of the pharmacist-managed HF medication titration clinic and a group of patients (n = 27) enrolled in the medication titration clinic during its first six months of operation indicated that target ACEI and ARB doses were achieved in a significantly higher percentage of pharmacist-managed titration clinic enrollees (52.9% versus 31%, p = 0.007). Patients enrolled in the pharmacist-managed HF medication titration clinic also had a significantly higher rate of attainment of optimal β-blocker doses (49% versus 24.7%, p = 0.012). Implementation of a pharmacist-managed HF medication titration clinic increased the percentage of patients achieving optimal ACEI, ARB, and β-blocker dosages.

A study of pH-dependent photodegradation of amiloride by a multivariate curve resolution approach to combined kinetic and acid-base titration UV data.

PubMed

De Luca, Michele; Ioele, Giuseppina; Mas, Sílvia; Tauler, Romà; Ragno, Gaetano

2012-11-21

Amiloride photostability at different pH values was studied in depth by applying Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) to the UV spectrophotometric data from drug solutions exposed to stressing irradiation. Resolution of all degradation photoproducts was possible by simultaneous spectrophotometric analysis of kinetic photodegradation and acid-base titration experiments. Amiloride photodegradation showed to be strongly dependent on pH. Two hard modelling constraints were sequentially used in MCR-ALS for the unambiguous resolution of all the species involved in the photodegradation process. An amiloride acid-base system was defined by using the equilibrium constraint, and the photodegradation pathway was modelled taking into account the kinetic constraint. The simultaneous analysis of photodegradation and titration experiments revealed the presence of eight different species, which were differently distributed according to pH and time. Concentration profiles of all the species as well as their pure spectra were resolved and kinetic rate constants were estimated. The values of rate constants changed with pH and under alkaline conditions the degradation pathway and photoproducts also changed. These results were compared to those obtained by LC-MS analysis from drug photodegradation experiments. MS analysis allowed the identification of up to five species and showed the simultaneous presence of more than one acid-base equilibrium.

Comparison of the clinical outcomes between unattended home APAP and polysomnography manual titration in obstructive sleep apnea patients.

PubMed

Wongsritrang, Krongthong; Fueangkamloon, Sumet

2013-09-01

To compare the clinical outcomes and determine the difference in therapeutic pressure between Automatic positive airway pressure (APAP) and polysomnography manual titration. Fifty patients of obstructive sleep apnea (OSA), moderate to severe cases, were randomized into two groups of intervention: 95-percentile pressure derived from APAP titration and an optimal pressure derived from manual titration. Clinical outcomes were assessed before and after four weeks. The average 95-percentile pressure derived from APAP titration was 11.7 +/- 0.3 cmH2O with median mask leak 1.3 L/min. The average optimal pressure derived from manual titration was 8.2 +/- 0.3 cmH2O. Pearson correlation analysis showed weak positive correlation (r = 0.336, p = 0.017). The Epworth Sleepiness Score (ESS), Quality of life tests: PSQI (Pittsburg Sleep Quality Index), and SF-36 (Medical Outcomes Study 36-Item Short-Form Health Survey) were improved significantly in both groups, but there were no statistical significant differences between groups. An APAP titration is an effective method of pressure determination for conventional CPAP therapy and shows no difference in clinical outcomes comparing the standard titration.

Peroxydisulfate Oxidation of L-Ascorbic Acid for Its Direct Spectrophotometric Determination in Dietary Supplements

NASA Astrophysics Data System (ADS)

Salkić, M.; Selimović, A.; Pašalić, H.; Keran, H.

2014-03-01

A selective and accurate direct spectrophotometric method was developed for the determination of L-as cor bic acid in dietary supplements. Background correction was based on the oxidation of L-ascorbic acid by potassi um peroxydisulfate in an acidic medium. The molar absorptivity of the proposed method was 1.41 · 104 l/(mol · cm) at 265 nm. The method response was linear up to an L-ascorbic acid concentration of 12.00 μg/ml. The detection limit was 0.11 μg/ml, and the relative standard deviation was 0.9 % (n = 7) for 8.00 μg/ml L-ascorbic acid. Other compounds commonly found in the dietary supplements did not interfere with the detection of L-ascorbic acid. The proposed procedure was successfully applied to the determination of L-ascorbic acid in these supplements, and the results obtained agreed with those obtained by iodine titration.

Acute and Perioperative Care of the Burn-Injured Patient

PubMed Central

Bittner, Edward A.; Shank, Erik; Woodson, Lee; Martyn, J.A. Jeevendra

2016-01-01

Care of burn-injured patients requires knowledge of the pathophysiologic changes affecting virtually all organs from the onset of injury until wounds are healed. Massive airway and/or lung edema can occur rapidly and unpredictably after burn and/or inhalation injury. Hemodynamics in the early phase of severe burn injury are characterized by a reduction in cardiac output, increased systemic and pulmonary vascular resistance. Approximately 2–5 days after major burn injury, a hyperdynamic and hypermetabolic state develops. Electrical burns result in morbidity much higher than expected based on burn size alone. Formulae for fluid resuscitation should serve only as guideline; fluids should be titrated to physiologic end points. Burn injury is associated basal and procedural pain requiring higher than normal opioid and sedative doses. Operating room concerns for the burn-injured patient include airway abnormalities, impaired lung function, vascular access, deceptively large and rapid blood loss, hypothermia and altered pharmacology. PMID:25485468

Weak acid-concentration Atot and dissociation constant Ka of plasma proteins in racehorses.

PubMed

Stampfli, H R; Misiaszek, S; Lumsden, J H; Carlson, G P; Heigenhauser, G J

1999-07-01

The plasma proteins are a significant contributor to the total weak acid concentration as a net anionic charge. Due to potential species difference, species-specific values must be confirmed for the weak acid anionic concentrations of proteins (Atot) and the effective dissociation constant for plasma weak acids (Ka). We studied the net anion load Atot of equine plasma protein in 10 clinically healthy mature Standardbred horses. A multi-step titration procedure, using a tonometer covering a titration range of PCO2 from 25 to 145 mmHg at 37 degrees C, was applied on the plasma of these 10 horses. Blood gases (pH, PCO2) and electrolytes required to calculate the strong ion difference ([SID] = [(Na(+) + K(+) + Ca(2+) + Mg(2+))-(Cl(-) + Lac(-) + PO4(2-))]) were simultaneously measured over a physiological pH range from 6.90-7.55. A nonlinear regression iteration to determine Atot and Ka was performed using polygonal regression curve fitting applied to the electrical neutrality equation of the physico-chemical system. The average anion-load Atot for plasma protein of 10 Standardbred horses was 14.89 +/- 0.8 mEq/l plasma and Ka was 2.11 +/- 0.50 x 10(-7) Eq/l (pKa = 6.67). The derived conversion factor (iterated Atot concentration/average plasma protein concentration) for calculation of Atot in plasma is 0.21 mEq/g protein (protein-unit: g/l). This value compares closely with the 0.24 mEq/g protein determined by titration of Van Slyke et al. (1928) and 0.22 mEq/g protein recently published by Constable (1997) for horse plasma. The Ka value compares closely with the value experimentally determined by Constable in 1997 (2.22 x 10(7) Eq/l). Linear regression of a set of experimental data from 5 Thoroughbred horses on a treadmill exercise test, showed excellent correlation with the regression lines not different from identity for the calculated and measured variables pH, HCO3 and SID. Knowledge of Atot and Ka for the horse is useful especially in exercise studies and in clinical conditions to quantify the mechanisms of the acid-base disturbances occurring.

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

PubMed

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

2015-02-01

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

Initial Evaluation of a Titration Appliance for Temporary Treatment of Obstructive Sleep Apnea.

PubMed

Levendowski, Daniel J; Morgan, Todd; Westbrook, Philip

2012-01-01

Custom oral appliances that adjustably advance the mandible provide superior outcomes when treating patients with moderate or severe sleep apnea. Custom appliances, however, are expensive, must be fitted by a dentist, and the likelihood of successful outcomes are difficult to predict. An inexpensive trial appliance, if proven efficacious, might be used to predict custom appliance outcomes or to provide temporary therapeutic benefit. The aim of this initial study was to assess the treatment efficacy of a novel titration oral appliance with that of an optimized custom appliance. Seventeen patients, treated with a custom oral appliance for at least one year, successfully completed a three-night home sleep test. The baseline obstructive sleep apnea severity was established on Night 1 with seven patients exhibiting severe, six moderate and four mild apnea/hypopnea indexes. Patients were randomly assigned to wear their custom appliance or the titration appliance on Nights 2 and 3. Significant reductions in the mean overall and supine apnea indexes (p < 0.05), and the overall (p < 0.01) and supine (p < 0.05) apnea/hypopnea indexes were observed for both the titration and custom appliances. The proportion of patients who exhibited at least a 50% reduction in the overall apnea index and supine apnea/hypopnea were similar for the titration and custom appliance (~60%). The custom appliance reduced the overall apnea/hypopnea index by 50% in a greater proportion of the patients compared to the titration appliance (77% vs. 53%). The titration appliance significantly reduced the degree of hypoxic exposure across sleep disordered breathing events overall (p < 0.05) and supine (p < 0.01). Patients found their custom appliance was more comfortable than the titration appliance, but preferred the titration appliance to no therapy. The titration appliance may be useful in assessing oral appliance treatment efficacy. When set to 70% of maximum protrusion, the titration appliance may provide immediate, temporary therapeutic benefit.

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

PubMed

Legangneux, Eric; Gardin, Anne; Johns, Donald

2013-03-01

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. 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. 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. Both titration regimens effectively attenuated the initial bradyarrhythmia observed on day 1 of treatment with BAF312 10 mg. © 2012 Novartis Institutes for BioMedical Research (NIBIR). British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.

Initial Evaluation of a Titration Appliance for Temporary Treatment of Obstructive Sleep Apnea

PubMed Central

Levendowski, Daniel J.; Morgan, Todd; Westbrook, Philip

2015-01-01

Background Custom oral appliances that adjustably advance the mandible provide superior outcomes when treating patients with moderate or severe sleep apnea. Custom appliances, however, are expensive, must be fitted by a dentist, and the likelihood of successful outcomes are difficult to predict. An inexpensive trial appliance, if proven efficacious, might be used to predict custom appliance outcomes or to provide temporary therapeutic benefit. Objective The aim of this initial study was to assess the treatment efficacy of a novel titration oral appliance with that of an optimized custom appliance. Methods Seventeen patients, treated with a custom oral appliance for at least one year, successfully completed a three-night home sleep test. The baseline obstructive sleep apnea severity was established on Night 1 with seven patients exhibiting severe, six moderate and four mild apnea/hypopnea indexes. Patients were randomly assigned to wear their custom appliance or the titration appliance on Nights 2 and 3. Results Significant reductions in the mean overall and supine apnea indexes (p < 0.05), and the overall (p < 0.01) and supine (p < 0.05) apnea/hypopnea indexes were observed for both the titration and custom appliances. The proportion of patients who exhibited at least a 50% reduction in the overall apnea index and supine apnea/hypopnea were similar for the titration and custom appliance (~60%). The custom appliance reduced the overall apnea/hypopnea index by 50% in a greater proportion of the patients compared to the titration appliance (77% vs. 53%). The titration appliance significantly reduced the degree of hypoxic exposure across sleep disordered breathing events overall (p < 0.05) and supine (p < 0.01). Patients found their custom appliance was more comfortable than the titration appliance, but preferred the titration appliance to no therapy. Conclusion The titration appliance may be useful in assessing oral appliance treatment efficacy. When set to 70% of maximum protrusion, the titration appliance may provide immediate, temporary therapeutic benefit. PMID:26523244

Heat shock protein expression as guidance for the therapeutic window of retinal laser therapy

NASA Astrophysics Data System (ADS)

Wang, Jenny; Huie, Philip; Dalal, Roopa; Lee, Seungjun; Tan, Gavin; Lee, Daeyoung; Lavinksy, Daniel; Palanker, Daniel

2016-03-01

Unlike conventional photocoagulation, non-damaging retinal laser therapy (NRT) limits laser-induced heating to stay below the retinal damage threshold and therefore requires careful dosimetry. Without the adverse effects associated with photocoagulation, NRT can be applied to critical areas of the retina and repeatedly to manage chronic disorders. Although the clinical benefits of NRT have been demonstrated, the mechanism of therapeutic effect and width of the therapeutic window below damage threshold are not well understood. Here, we measure activation of heat shock response via laser-induced hyperthermia as one indication of cellular response. A 577 nm laser is used with the Endpoint Management (EpM) user interface, a titration algorithm, to set experimental pulse energies relative to a barely visible titration lesion. Live/dead staining and histology show that the retinal damage threshold in rabbits is at 40% of titration energy on EpM scale. Heat shock protein 70 (HSP70) expression in the retinal pigment epithelium (RPE) was detected by whole-mount immunohistochemistry after different levels of laser treatment. We show HSP70 expression in the RPE beginning at 25% of titration energy indicating that there is a window for NRT between 25% and 40% with activation of the heat shock protein expression in response to hyperthermia. HSP70 expression is also seen at the perimeter of damaging lesions, as expected based on a computational model of laser heating. Expression area for each pulse energy setting varied between laser spots due to pigmentation changes, indicating the relatively narrow window of non-damaging activation and highlighting the importance of proper titration.

Acidic beverages increase the risk of in vitro tooth erosion

PubMed Central

Ehlen, Leslie A.; Marshall, Teresa A.; Qian, Fang; Wefel, James S.; Warren, John J.

2008-01-01

Acidic beverages are thought to increase the potential for dental erosion. We report pH and titratable acidities (i.e., quantity of base required to bring a solution to neutral pH) of beverages popular in the United States and lesion depths in enamel and root surfaces following beverage exposure, and we describe associations among pH, titratable acidity and both enamel and root erosive lesion depths. The pH of 100% juices, regular sodas, diet sodas and sports drinks upon opening, and the titratable acidity both upon opening and after 60 minutes of stirring were measured. Enamel and root surfaces of healthy permanent molars and premolars were exposed to individual beverages (4 enamel and 4 root surfaces per beverage) for 25 hours and erosion was measured. Statistical analyses included two-sample t-tests, analyses of variance with post hoc Tukey’s studentized range test; and Spearman rank correlation coefficients. All beverages were acidic; the titratable acidity of energy drinks was greater than regular sodas and diet sodas which were greater than 100% juices and sports drinks (P<0.05). Enamel lesion depths following beverage exposures were greatest for Gatorade® followed by Red Bull® and Coke® which were greater than Diet Coke® and 100% apple juice (P <0.05). Root lesion depths were greatest for Gatorade® followed by Red Bull®, Coke®, 100% apple juice and Diet Coke® (P<0.05). Lesion depths were not associated with pH or titratable acidity. Beverages popular in the United States can produce dental erosion. PMID:19083423

Control of OSA during automatic positive airway pressure titration in a clinical case series: predictors and accuracy of device download data.

PubMed

Huang, Hsin-Chia Carol; Hillman, David R; McArdle, Nigel

2012-09-01

To investigate the factors associated with physiologic control of obstructive sleep apnea (OSA) during automatic positive airway pressure (APAP) titration in a clinical series. To also assess the usefulness of apnea-hypopnea index (AHI) data downloaded from the APAP device (Dev AHI). Retrospective review of a consecutive series of patients with OSA who underwent APAP titration (Autoset Spirit, ResMed, Bella Vista, New South Wales, Australia ) with simultaneous polysomnographic (PSG) monitoring in the sleep laboratory. Tertiary sleep clinic. There were 190 consecutive patients with OSA referred for APAP titration. There were 58% of patients who achieved optimal or good control of OSA (titration PSG AHI < 10, or at least 50% reduction in AHI if diagnostic AHI < 15/hr) during APAP titration. The independent predictors of titration PSG AHI were a history of cardiac disease and elevated central apnea and arousal indices during the diagnostic study. Although the median and interquartile range (IQR) AHI from the device (7.0, 3.9-11.6 events/hr) was only slightly less than the PSG AHI (7.8, 3.9-14.4 events/hr, P = 0.04) during titration, case-by-case agreement between the two measures was poor (chi-square < 0.001). In a clinical sample control of OSA during APAP titration is often poor, and close clinical follow-up is particularly needed in patients with a history of cardiac disease or with high arousal or central apnea indices on the diagnostic study. Device AHI does not reliably assess control during APAP titration, and PSG assessment may be required if clinical response to treatment is poor. The findings relate to the ResMed AutoSet device and may not apply to other devices.

An RCT Investigating Patient-Driven Versus Physician-Driven Titration of BIAsp 30 in Patients with Type 2 Diabetes Uncontrolled Using NPH Insulin.

PubMed

Chraibi, Abdelmjid; Al-Herz, Shoorook; Nguyen, Bich Dao; Soeatmadji, Djoko W; Shinde, Anil; Lakshmivenkataraman, Balasubramanian; Assaad-Khalil, Samir H

2017-08-01

The aim of this study was to confirm the efficacy of patient-driven titration of BIAsp 30 in terms of glycemic control, by comparing it to physician-driven titration of BIAsp 30, in patients with type 2 diabetes in North Africa, the Middle East, and Asia. A 20-week, open-label, randomized, two-armed, parallel-group, multicenter study in Egypt, Indonesia, Morocco, Saudi Arabia, and Vietnam. Patients (n = 155) with type 2 diabetes inadequately controlled using neutral protamine Hagedorn (NPH) insulin were randomized to either patient-driven or physician-driven BIAsp 30 titration. The noninferiority of patient-driven compared to physician-driven titration with respect to the reduction in HbA1c was confirmed. The estimated mean change in HbA1c from baseline to week 20 was -1.27% in the patient-driven arm and -1.04% in the physician-driven arm, with an estimated treatment difference of -0.23% (95% confidence interval: -0.54; 0.08). After 20 weeks of treatment, the proportions of patients achieving the target of HbA1c <7.5% were similar between titration arms; the proportions of patients achieving the target of ≤6.5% were also similar. Both titration algorithms were well tolerated, and hypoglycemic episode rates were similar in both arms. Patient-driven titration of BIAsp 30 can be as effective and safe as physician-driven titration in non-Western populations. Overall, the switch from NPH insulin to BIAsp 30 was well tolerated in both titration arms and led to improved glycemic control. A limitation of the study was the relatively small number of patients recruited in each country. ClinicalTrials.gov NCT01589653. Novo Nordisk A/S, Denmark.

Persistent benefits of slow titration of paroxetine in a six-month follow-up.

PubMed

Olgiati, Paolo; Serretti, Alessandro

2015-09-01

Paroxetine titration may be difficult in older individuals as they are more sensitive to side effects. The current study extends to 6 months our previously published report in which paroxetine was started at 2.5 mg/day and slowly increased by 2.5 mg on alternate days (slow titration) or rapidly titrated to target dose from 10 mg/day (standard titration) in a naturalistic setting. Here, the follow-up period was extended to 26 weeks. We performed an intent-to-treat analysis of 47 subjects from the original sample (major depressive disorder and/or generalized anxiety disorder (GAD); >60 years of age). Missing evaluations were replaced by last observations carried forward. GAD was included as a stratification factor. Patients in whom paroxetine was slowly up-titrated were more likely to remit (84.0% vs 54.5%; p = 0.028) and had lower core depression (p = 0.0015) and psychic anxiety levels (p = 0.006) after 26 weeks. Dropout rate was 20% in the slow titration group compared with 77.3% in the standard titration arm (p < 0.001). Patients with GAD accounted for all significant associations. No substantial differences were reported between slow and standard titration groups in the subsample without GAD. Despite some limitations, these findings suggest that paroxetine treatment should be started at lower doses in older depressed patients and slowly up-titrated. This strategy would allow to increase antidepressant response and the likelihood of completing treatment cycle in patients with high anxiety levels and GAD comorbidity. Copyright © 2015 John Wiley & Sons, Ltd.

Up-titration of allopurinol in patients with gout.

PubMed

Jennings, Claudine G; Mackenzie, Isla S; Flynn, Rob; Ford, Ian; Nuki, George; De Caterina, Raffaele; Riches, Philip L; Ralston, Stuart H; MacDonald, Thomas M

2014-08-01

European League against Rheumatism (EULAR) gout management guidelines recommend achieving a target urate level <6.0 mg/dL (<357 µmol/L). Allopurinol is the most widely used urate-lowering therapy; however, many gout patients who are prescribed allopurinol do not have urate levels optimally controlled. The objective of this analysis was to review the efficacy and tolerability of allopurinol up-titration in achieving the EULAR target levels. The Febuxostat versus Allopurinol Streamlined Trial (FAST) is an ongoing multi-centre study comparing the cardiovascular safety of febuxostat and allopurinol (target recruitment: 5706 patients). Recruited patients were already taking allopurinol and the protocol required up-titration of daily allopurinol dose, in 100 mg increments, to achieve the EULAR urate target level prior to randomisation. We reviewed pre-randomisation data from the first 400 recruited and subsequently randomised FAST patients. Of 400 patients, 144 (36%) had urate levels ≥357 µmol/L at screening and required allopurinol up-titration. Higher urate levels were significantly associated with lower allopurinol dose, male sex, increased BMI, increased alcohol intake and diuretic use. Mean fall in urate levels after a single 100-mg dose increase was 71 µmol/L. The number of up-titrations required ranged from one to five (median = 1) with 65% of patients controlled after one 100-mg up-titration. Overall, 97% of up-titrated patients achieved target urate levels with median final allopurinol dose of 300 mg daily. Side effects and complications of up-titration were minimal. Overall, 36% of FAST patients were not at target urate levels and required up-titration. Allopurinol up-titration was effective in achieving urate target levels and was generally well tolerated by patients. Copyright © 2014 Elsevier Inc. All rights reserved.

Parametric changes in response equilibrium during an intra-cranial self stimulation (ICSS) task: can reward value be assessed independently of absolute threshold?

PubMed

Easterling, K W; Holtzman, S G

1997-01-01

Traditional ICSS methodologies have attempted to evaluate changes in the rewarding value of brain stimulation by assessing the lowest value of the stimulation that will support responding. However, orderly changes in suprathreshold indicants of hedonic magnitude such as titration point have been shown. In the present experiments, rats were trained to respond on two ICSS autotitration schedules in which every response on one lever produced stimulation of the medial forebrain bundle, and every Xth response decreased either the stimulation current or the stimulation frequency. At any time, a response on a second "reset" lever restored the stimulation current or frequency available on the stimulation lever to its starting level and operationally defined changes in "reward value". In order to study this titration point measure, two response requirements (responses/stepdown; step size) and two stimulation parameters (initial stimulation level; train duration) were systematically varied. Under both current and frequency titration schedules, data indicated that response rate and titration point remained stable over repeated trials and multiple testing days--parameters being constant. Across all conditions, compared to the frequency titration schedule, subjects responding under the current titration schedule showed significantly higher titration points and lower rates of responding. Indicating the independence of rate and titration point data, parametric manipulations did not affect titration point and rate data concurrently. Results support the conclusion that titration point is a relative measure of "reward value" that is generally independent of response rate, but that is affected by manipulations that alter the amount of stimulation available between "resets". Additional work is needed in order to determine the relationship between the magnitude of stimulation needed to maintain minimal responding and that needed to maintain response equilibrium in an autotitration task.

Viscoelastic Tamponade Applied to the Ocular Surface for Enhanced Control of Gaseous Egress From the Anterior Chamber During Final Bubble Titration in DMEK Surgery: The "Polite" Burp.

PubMed

Sales, Christopher S; Fernandez, Ana Alzaga; Anwar, Zane

2018-07-01

To present a novel technique for enhancing the surgeon's control over the volume of air or gas that is "burped" from the anterior chamber during final bubble and intraocular pressure (IOP) titration in Descemet membrane endothelial keratoplasty. After ascertaining that the intracameral bubble is either too large and/or has rendered IOP too high, a bead of ophthalmic viscoelastic is applied to the ocular surface over a paracentesis incision, which is then depressed in the usual fashion to burp gas from the anterior chamber. The weight and viscosity of the viscoelastic create a tamponade that slows the egress of gas from the anterior chamber, thereby making it more controllable. If the bubble size or IOP needs to be reduced at the conclusion of the Descemet membrane endothelial keratoplasty procedure, application of ophthalmic viscoelastic over the paracentesis can enhance the surgeon's control over the volume of gas burped from the anterior chamber, thereby reducing the tendency to swing between a bubble that is too large or too small.

Structural changes in calcium-binding allergens: use of circular dichroism to study binding characteristics.

PubMed

Hebenstreit, D; Ferreira, F

2005-09-01

Several studies showed that calcium-binding proteins have a fixed place in the spectrum of allergenic substances. Often the binding of a calcium ion induces conformational changes and affects immunoglobulin E-binding to the allergen. Hence, the quantitative characterization of the binding to calcium is of importance to understand both the biologic and allergenic activity of these proteins. In the present study we describe a procedure for determining the stoichiometry and dissociation constant (K(D)) of calcium-binding allergens using circular dichroism (CD) techniques. For the experiments, we used recombinant Bet v 4, a two EF-hand allergen from birch pollen. Solutions of Bet v 4 were titrated with calcium and the change in molar ellipticity at 222 nm was monitored with a CD spectropolarimeter. The determination of the binding stoichiometry as well as of the K(D) for one EF-hand (4 microM) demonstrated the applicability of the method. CD-monitored calcium-titration of protein solutions represents a fast and easy method for determining the binding characteristics of calcium-binding allergens.

Economic benefit of back titration in the treatment of hypertension in Jos, Nigeria.

PubMed

Okeahialam, Basil N; Adeniyi, Michael A

2017-01-01

Treatment of hypertension is expensive and cost is one of the reasons for inadequate blood pressure control. Where there are no social cost cushions, the burden is borne by patients. With pervasive poverty and inadequate control, complications are unchecked. Back titration in appropriate circumstances should, therefore, translate to economic benefit. This is an attempt to compute, in economic terms, the benefit of back titration. Thirty-nine patients who entered an antihypertensive back titration program for 12 months and who had been earlier reported on, form the subject of this study. A survey of the cost of antihypertensives in pharmacy outlets in Jos, Nigeria was undertaken. Regimens of antihypertensives that patients were on at the onset and end of the 12 months of back titration were costed in Nigerian currency and compared. Back titration translated to economic benefit in all patients with a cost reduction varying from 2.3% to 100%. This reflected in reduction in mean daily cost of treatment of N107.09-N54.61. The benefit of antihypertensive back titration apart from psychological relief of lower pill burden and side effect profile is in pharmacoeconomics. This permits greater adherence and prevents morbi-mortality consequences of hypertension. In this study, back titration over 12 months translated to average cost reduction of >50%, making treatment more affordable. In appropriate circumstances, back titration of antihypertensives results in economic relief for patients. This should improve adherence, reduce morbi-mortality and is recommended for wider application.

Differential Binding Models for Direct and Reverse Isothermal Titration Calorimetry.

PubMed

Herrera, Isaac; Winnik, Mitchell A

2016-03-10

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

Surface electrochemical properties of red mud (bauxite residue): zeta potential and surface charge density.

PubMed

Liu, Yanju; Naidu, Ravendra; Ming, Hui

2013-03-15

The surface electrochemical properties of red mud (bauxite residue) from different alumina refineries in Australia and China were studied by electrophoresis and measuring surface charge density obtained from acid/base potentiometric titrations. The electrophoretic properties were measured from zeta potentials obtained in the presence of 0.01 and 0.001 M KNO(3) over a wide pH range (3.5-10) by titration. The isoelectric point (IEP) values were found to vary from 6.35 to 8.70 for the red mud samples. Further investigation into the surface charge density of one sample (RRM) by acid/base potentiometric titration showed similar results for pH(PZC) with pH(IEP) obtained from electrokinetic measurements. The pH(IEP) determined from zeta potential measurements can be used as a characteristic property of red mud. The minerals contained in red mud contributed to the different values of pH(IEP) of samples obtained from different refineries. Different relationships of pH(IEP) with Al/Fe and Al/Si ratios (molar basis) were also found for different red mud samples. Copyright © 2012 Elsevier Inc. All rights reserved.

A rapid method for infectivity titration of Andes hantavirus using flow cytometry.

PubMed

Barriga, Gonzalo P; Martínez-Valdebenito, Constanza; Galeno, Héctor; Ferrés, Marcela; Lozach, Pierre-Yves; Tischler, Nicole D

2013-11-01

The focus assay is currently the most commonly used technique for hantavirus titer determination. This method requires an incubation time of between 5 and 11 days to allow the appearance of foci after several rounds of viral infection. The following work presents a rapid Andes virus (ANDV) titration assay, based on viral nucleocapsid protein (N) detection in infected cells by flow cytometry. To this end, an anti-N monoclonal antibody was used that was developed and characterized previously. ANDV N could be detected as early as 6 h post-infection, while viral release was not observed until 24-48 h post-infection. Given that ANDV detection was performed during its first round of infection, a time reduction for titer determination was possible and provided results in only two days. The viral titer was calculated from the percentage of N positive cells and agreed with focus assay titers. Furthermore, the assay was applied to quantify the inhibition of ANDV cell entry by patient sera and by preventing endosome acidification. This novel hantavirus titration assay is a highly quantitative and sensitive tool that facilitates infectivity titration of virus stocks, rapid screening for antiviral drugs, and may be further used to detect and quantify infectious virus in human samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Titration in the treatment of the more troubled patient.

PubMed

Winer, J A; Ornstein, E D

2001-01-01

This article defines and discusses a modification of technique recommended by the authors in the psychoanalytic treatment of more troubled patients--a modification they call titration. Titration is defined as a conscious decision by the analyst to increase or decrease assistance (or gratification) gradually, in order to facilitate the analytic process. The authors emphasize the complexity of decisions in treatment by focusing on the decision-making processes that titration requires. Guidelines and a case vignette are presented. The authors conclude by considering some of the politics involved in the introduction of technique modifications, the salience of the titration concept, and directions for further exploration.

Influence of levels of information as presented by different technologies on students' understanding of acid, base, and ph concepts

NASA Astrophysics Data System (ADS)

Nakhleh, Mary B.; Krajcik, Joseph S.

We investigated how different levels of information presented by various technologies affected secondary students' understanding of acid, base, and pH concepts. Secondary students who were selected for the study had just completed their study of acid-base chemistry. No attempt was made to provide further instruction. We analyzed changes in the understanding of individual students by constructing concept maps from the propositions that the students used in interviews conducted before and after a series of acid-base titrations. After the initial interview, students were divided into three groups. Within each group, students individually performed the same set of titrations using different technologies: chemical indicators, pH meters, and microcomputer-based laboratories (MBL). After the titrations were completed, all students were interviewed again. We found that students using MBL exhibited a larger positive shift in their concept map scores, which indicates a greater differentiation and integration of their knowledge of acids and bases. The chemical indicator students exhibited a more moderate positive shift in their concept map scores, and the pH meter students exhibited a smaller positive shift. We also found that the MBL students constructed more inappropriate links in their concept maps than the chemical indicator or pH meter students. However, we speculate that this increased number of inappropriate links indicates a high level of involvement with the technology. We therefore argue that the level of information offered by the technology affected students' understanding of the chemical concepts.Received: 24 February 1993; Revised: 21 February 1994;

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

PubMed Central

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

2011-01-01

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

The Conjugate Acid-Base Chart.

ERIC Educational Resources Information Center

Treptow, Richard S.

1986-01-01

Discusses the difficulties that beginning chemistry students have in understanding acid-base chemistry. Describes the use of conjugate acid-base charts in helping students visualize the conjugate relationship. Addresses chart construction, metal ions, buffers and pH titrations, and the organic functional groups and nonaqueous solvents. (TW)

On-Board Monitoring of Engine Oil

DTIC Science & Technology

2011-04-01

Viscosity of Transparent and Opaque Liquids at 40°C Infracal Soot Meter Karl Fischer Titration ASTM D 664 Standard Test Method for Acid Number of... methods involve potentiometric and colorimetric titrations, respectively. For both tests, a titration solvent is prepared and added to the oil. The...ASTM D 2896 and ASTM D 4739 [17]. Both methods involve potentiometric titrations. ASTM D 2896 uses a stronger acid and more polar solvent than ASTM D

Efficacy and Tolerability of Two Different Kinds of Titration of Paroxetine Hydrocloride Solution: an Observational Study.

PubMed

Ielmini, Marta; Poloni, Nicola; Caselli, Ivano; Bianchi, Lucia; Diurni, Marcello; Vender, Simone; Callegari, Camilla

2018-03-13

Depressive disorders are expected to be the second highest cause of morbidity in the world until few years. Moreover, patients with depression frequently show many side effects and low compliance to therapy. To find a more tolerated and more efficacy therapy is a growing need. This observational study investigates the efficacy, safety and tolerability of paroxetine hydrochloride comparing slow versus standard titration in a population affected by Depressive Disoders (according to DSM 5). 186 outpatients were assessed throught the following scales: Hamilton Depression Rating Scale (HDRS) for depression and World Health Organization Quality of Life Scale Bref for the perceived quality of life (WHOQOL BREF). Treatment-emerged Adverse Events (TEAEs) were recorded throught self-reports. Statystical analysys was performed by GraphPad Prism Version 5.1. The efficacy of paroxetine was confirmed in both titrations by the number of clinical remitters (HDRS ≤ 7 at 12 weeks for 53% of the standard titration group and 58% of the slow titration group), without differences. About safety and tolerability there were more frequent TEAEs among the standard titration group (p < 0.01). Comparing WHOQOL BREF between the two groups at the recruitment and at the twelth week emerged a statistically significant difference (p = 0.003), with highest scores reached in slow titration group. Although the short observation period is an evident limit, this study is consistent to the literature about the efficacy of both titrations of paroxetine to improve depression and shows promising results about the increased tolerability of paroxetine slow titration.

Interagency comparison of iodometric methods for ozone determination

NASA Technical Reports Server (NTRS)

Demore, W. B.; Romanovsky, J. C.; Feldstein, M.; Mueller, P. K.; Hamming, W. J.

1976-01-01

The California Air Resources Board appointed an Oxidant Calibration Committee for the purpose of evaluating the accuracy of the different agency calibration procedures. The committee chose UV absorption photometry as the reference method for ozone measurement. Interagency comparisons of the various iodometric methods were conducted relative to the ultraviolet standard. The tests included versions of the iodometric methods as employed by the Air Resources Board, the Los Angeles Air Pollution Control District, and the EPA. An alternative candidate reference method for ozone measurement, gas phase titration, was also included in the test series.

Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

NASA Technical Reports Server (NTRS)

May, R. D.; Molina, L. T.; Webster, C. R.

1988-01-01

A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

Synthesis of Side Chain Liquid Crystal Polymers by Living Ring Opening Metathesis Polymerization. 3. Influence of Molecular Weight, Interconnecting Unit and Substituent on the Mesomorphic behavior of Polymers with Laterally Attached Mesogens

DTIC Science & Technology

1992-04-08

polymethylsiloxanes, 6 -7 polyacrylates ,2,4,5 polymethacrylates, 1 ,3 and polychloroacrylates, 5 exhibit only nematic mesophases regardless of the...corresponding carboxyl chloride. Potassium bicyclo[2.2.1]hept-2-ene-5- carboxylate was prepared by titrating a methanolic solution of the carboxylic acid...Esterification of the Corresponding Benzyl Bromides. Monomers 1I-n were prepared in 47-88% yield using the following procedure. A mixture of potassium bicyclo

A simple and rapid Hepatitis A Virus (HAV) titration assay based on antibiotic resistance of infected cells: evaluation of the HAV neutralization potency of human immune globulin preparations

PubMed Central

Konduru, Krishnamurthy; Virata-Theimer, Maria Luisa; Yu, Mei-ying W; Kaplan, Gerardo G

2008-01-01

Background Hepatitis A virus (HAV), the causative agent of acute hepatitis in humans, is an atypical Picornaviridae that grows poorly in cell culture. HAV titrations are laborious and time-consuming because the virus in general does not cause cytopathic effect and is detected by immunochemical or molecular probes. Simple HAV titration assays could be developed using currently available viral construct containing selectable markers. Results We developed an antibiotic resistance titration assay (ARTA) based on the infection of human hepatoma cells with a wild type HAV construct containing a blasticidin (Bsd) resistance gene. Human hepatoma cells infected with the HAV-Bsd construct survived selection with 2 μg/ml of blasticidin whereas uninfected cells died within a few days. At 8 days postinfection, the color of the pH indicator phenol red in cell culture media correlated with the presence of HAV-Bsd-infected blasticidin-resistant cells: an orange-to-yellow color indicated the presence of growing cells whereas a pink-to-purple color indicated that the cells were dead. HAV-Bsd titers were determined by an endpoint dilution assay based on the color of the cell culture medium scoring orange-to-yellow wells as positive and pink-to-purple wells as negative for HAV. As a proof-of-concept, we used the ARTA to evaluate the HAV neutralization potency of two commercially available human immune globulin (IG) preparations and a WHO International Standard for anti-HAV. The three IG preparations contained comparable levels of anti-HAV antibodies that neutralized approximately 1.5 log of HAV-Bsd. Similar neutralization results were obtained in the absence of blasticidin by an endpoint dilution ELISA at 2 weeks postinfection. Conclusion The ARTA is a simple and rapid method to determine HAV titers without using HAV-specific probes. We determined the HAV neutralization potency of human IG preparations in 8 days by ARTA compared to the 14 days required by the endpoint dilution ELISA. The ARTA reduced the labour, time, and cost of HAV titrations making it suitable for high throughput screening of sera and antivirals, determination of anti-HAV antibodies in human immune globulin preparations, and research applications that involve the routine evaluation of HAV titers. PMID:19094229

Sedation and analgesia in gastrointestinal endoscopy: What’s new?

PubMed Central

Fanti, Lorella; Testoni, Pier Alberto

2010-01-01

Various types of sedation and analgesia technique have been used during gastrointestinal endoscopy procedures. The best methods for analgesia and sedation during gastrointestinal endoscopy are still debated. Providing an adequate regimen of sedation/analgesia might be considered an art, influencing several aspects of endoscopic procedures: the quality of the examination, the patient’s cooperation and the patient’s and physician’s satisfaction with the sedation. The properties of a model sedative agent for endoscopy would include rapid onset and offset of action, analgesic and anxiolytic effects, ease of titration to desired level of sedation, rapid recovery and an excellent safety profile. Therefore there is an impulse for development of new approaches to endoscopic sedation. This article provides an update on the methods of sedation today available and future directions in endoscopic sedation. PMID:20503443

Titration Calorimetry Standards and the Precision of Isothermal Titration Calorimetry Data

PubMed Central

Baranauskienė, Lina; Petrikaitė, Vilma; Matulienė, Jurgita; Matulis, Daumantas

2009-01-01

Current Isothermal Titration Calorimetry (ITC) data in the literature have relatively high errors in the measured enthalpies of protein-ligand binding reactions. There is a need for universal validation standards for titration calorimeters. Several inorganic salt co-precipitation and buffer protonation reactions have been suggested as possible enthalpy standards. The performances of several commercial calorimeters, including the VP-ITC, ITC200, and Nano ITC-III, were validated using these suggested standard reactions. PMID:19582227

Control of OSA During Automatic Positive Airway Pressure Titration in a Clinical Case Series: Predictors and Accuracy of Device Download Data

PubMed Central

Huang, Hsin-Chia Carol; Hillman, David R.; McArdle, Nigel

2012-01-01

Study Objectives: To investigate the factors associated with physiologic control of obstructive sleep apnea (OSA) during automatic positive airway pressure (APAP) titration in a clinical series. To also assess the usefulness of apnea-hypopnea index (AHI) data downloaded from the APAP device (Dev AHI). Design: Retrospective review of a consecutive series of patients with OSA who underwent APAP titration (Autoset Spirit, ResMed, Bella Vista, New South Wales, Australia ) with simultaneous polysomnographic (PSG) monitoring in the sleep laboratory. Setting: Tertiary sleep clinic. Participants: There were 190 consecutive patients with OSA referred for APAP titration. Measurements and Results: There were 58% of patients who achieved optimal or good control of OSA (titration PSG AHI < 10, or at least 50% reduction in AHI if diagnostic AHI < 15/hr) during APAP titration. The independent predictors of titration PSG AHI were a history of cardiac disease and elevated central apnea and arousal indices during the diagnostic study. Although the median and interquartile range (IQR) AHI from the device (7.0, 3.9-11.6 events/hr) was only slightly less than the PSG AHI (7.8, 3.9-14.4 events/hr, P = 0.04) during titration, case-by-case agreement between the two measures was poor (chi-square < 0.001). Conclusion: In a clinical sample control of OSA during APAP titration is often poor, and close clinical follow-up is particularly needed in patients with a history of cardiac disease or with high arousal or central apnea indices on the diagnostic study. Device AHI does not reliably assess control during APAP titration, and PSG assessment may be required if clinical response to treatment is poor. The findings relate to the ResMed AutoSet device and may not apply to other devices. Citation: Huang HCC; Hillman DR; McArdle N. Control of OSA during automatic positive airway pressure titration in a clinical case series: predictors and accuracy of device download data. SLEEP 2012;35(9):1277–1283. PMID:22942506

Flow cytometry for enrichment and titration in massively parallel DNA sequencing

PubMed Central

Sandberg, Julia; Ståhl, Patrik L.; Ahmadian, Afshin; Bjursell, Magnus K.; Lundeberg, Joakim

2009-01-01

Massively parallel DNA sequencing is revolutionizing genomics research throughout the life sciences. However, the reagent costs and labor requirements in current sequencing protocols are still substantial, although improvements are continuously being made. Here, we demonstrate an effective alternative to existing sample titration protocols for the Roche/454 system using Fluorescence Activated Cell Sorting (FACS) technology to determine the optimal DNA-to-bead ratio prior to large-scale sequencing. Our method, which eliminates the need for the costly pilot sequencing of samples during titration is capable of rapidly providing accurate DNA-to-bead ratios that are not biased by the quantification and sedimentation steps included in current protocols. Moreover, we demonstrate that FACS sorting can be readily used to highly enrich fractions of beads carrying template DNA, with near total elimination of empty beads and no downstream sacrifice of DNA sequencing quality. Automated enrichment by FACS is a simple approach to obtain pure samples for bead-based sequencing systems, and offers an efficient, low-cost alternative to current enrichment protocols. PMID:19304748

Fast Proton Titration Scheme for Multiscale Modeling of Protein Solutions.

PubMed

Teixeira, Andre Azevedo Reis; Lund, Mikael; da Silva, Fernando Luís Barroso

2010-10-12

Proton exchange between titratable amino acid residues and the surrounding solution gives rise to exciting electric processes in proteins. We present a proton titration scheme for studying acid-base equilibria in Metropolis Monte Carlo simulations where salt is treated at the Debye-Hückel level. The method, rooted in the Kirkwood model of impenetrable spheres, is applied on the three milk proteins α-lactalbumin, β-lactoglobulin, and lactoferrin, for which we investigate the net-charge, molecular dipole moment, and charge capacitance. Over a wide range of pH and salt conditions, excellent agreement is found with more elaborate simulations where salt is explicitly included. The implicit salt scheme is orders of magnitude faster than the explicit analog and allows for transparent interpretation of physical mechanisms. It is shown how the method can be expanded to multiscale modeling of aqueous salt solutions of many biomolecules with nonstatic charge distributions. Important examples are protein-protein aggregation, protein-polyelectrolyte complexation, and protein-membrane association.

Evaluating paper degradation progress. Cross-linking between chromatographic, spectroscopic and chemical results

NASA Astrophysics Data System (ADS)

Łojewski, Tomasz; Zięba, Katarzyna; Knapik, Arkadiusz; Bagniuk, Jacek; Lubańska, Anna; Łojewska, Joanna

2010-09-01

The study presents an overview of the chromatographic (SEC), spectroscopic (FTIR, UV/VIS), viscometric (DP) and chemical methods (titration, pH) used for the evaluation of the degradation progress of various kinds of paper under various conditions. The methods were chosen to follow different routes of paper degradation. Model paper samples represented boundary paper types from pure cellulose cotton paper, through softwood to low quality acidic, sized groundwood paper The accelerated ageing conditions were adjusted to achieve maximum effect (climatic chamber RH 59%, 90oC) and also to mimic the environment inside books (closed vials). The results were settled on the literature data on the degradation mechanisms and compared in terms of the paper types and ageing conditions. The estimators of coupled de-polymerisation and oxidation have been proposed based on the correlation between SEC, UV/VIS and titrative coppper number determination. The overall oxidation index derived from FTIR results was shown to correlate with the summary -CHO and -COOH concentration determined by titrative methods.

Further optimization of culture method for rat keratinocytes: titration of glucose and sodium chloride.

PubMed

Oku, H; Yamashita, M; Iwasaki, H; Chinen, I

1999-02-01

The present study further improved the serum-free method of culturing rat keratinocytes. To obtain the best growth of rat keratinocytes, we modified our previous serum-free medium (MCDB153 based medium), particularly the amounts of glucose and sodium chloride (NaCl). Titration experiments showed the optimal concentration to be 0.8 mM for glucose and 100 mM for NaCl. This modification eliminated the requirement for albumin, which had been essential for colony formation when our previous medium was used. Titration of glucose and NaCl, followed by adjustment of essential amino acids and growth factors, produced a new formulation. More satisfactory and better growth was achieved with the new medium than with the previous medium. Accumulation of monoalkyldiacylglycerol (MADAG) was consistently noted in this study, representing the unusual lipid profile. A tendency toward normalization was, however, noted with the neutral lipid profile of keratinocytes cultivated in the new medium: lower production of MADAG was obtained with the new formulation, rather than the previous one.

A short 2 week dose titration regimen reduces the severity of flu-like symptoms with initial interferon gamma-1b treatment.

PubMed

Devane, John G; Martin, Mary L; Matson, Mark A

2014-06-01

Flu-like symptoms (FLS) are commonly experienced by patients receiving interferon gamma-1b which may cause discontinuation or disruption of dosing during initial therapy or on re-initiation following a break in therapy. In contrast to Type I interferons, the impact of dose-titration on FLS has not been reported and is not a practice described or included in the approved prescribing information for interferon gamma-1b.The objective of this study was to assess the effect of a 2 week titration regimen on the severity of FLS during the initial 3 weeks of therapy with three times weekly subcutaneous injections of interferon gamma-1b. Healthy men and women were randomized into a double-blind, two-period, crossover study. Each study period was 3 weeks in duration and there was a minimum 15 day washout between treatment periods. Two treatment regimens were compared: No Titration dosing (full 50 mcg/m(2) subcutaneously [s.c.] three times weekly for 3 weeks) and Titration (15 mcg/m(2) s.c. three times weekly during week 1, 30 mcg/m(2) s.c. three times weekly during week 2 followed by the full dose of 50 mcg/m(2) s.c. three times weekly during week 3). Subjects remained in the clinic for at least 12 hours following each injection. FLS was based on a composite score for fever, chills, tiredness and muscle aches assessed at baseline and 4, 8 and 12 hours following each injection. Acetaminophen was allowed at the discretion of the PI. The primary endpoint was the change from baseline in FLS severity at 8 hours averaged over the 3 weeks of treatment. Additional endpoints included FLS at 4 and 12 hours, individual flu-like symptoms, rates of discontinuation, incidence of FLS and acetaminophen use. NCT 01929382. Of the 40 subjects randomized, there were 15 (37.5%) discontinuations. Titration resulted in a significant reduction in FLS severity at 8 hours (p = 0.023) averaged over the 3 week treatment period. The difference in 3 week FLS severity reflects differences during week 1 treatment, indicating an early peak in FLS severity during the No Titration treatment and subsequent development of tolerance. In contrast, titration results in near baseline severity scores throughout the treatment period. Similar trends were seen for 4 and 12 hour FLS severity scores. Of the individual FLS, difference in fever severity was most marked. Safety profiles for both regimens were consistent with the approved prescribing information for interferon gamma-1b. Study limitations included the use of healthy subjects rather than disease subjects, the lack of a validated assessment tool for evaluating FLS and the relatively high discontinuation rate. A short 2 week, dose-titration regimen reduces FLS severity following interferon gamma-1b treatment initiation in normal subjects.

Comparison of methods for acid quantification: impact of resist components on acid-generating efficiency

NASA Astrophysics Data System (ADS)

Cameron, James F.; Fradkin, Leslie; Moore, Kathryn; Pohlers, Gerd

2000-06-01

Chemically amplified deep UV (CA-DUV) positive resists are the enabling materials for manufacture of devices at and below 0.18 micrometer design rules in the semiconductor industry. CA-DUV resists are typically based on a combination of an acid labile polymer and a photoacid generator (PAG). Upon UV exposure, a catalytic amount of a strong Bronsted acid is released and is subsequently used in a post-exposure bake step to deprotect the acid labile polymer. Deprotection transforms the acid labile polymer into a base soluble polymer and ultimately enables positive tone image development in dilute aqueous base. As CA-DUV resist systems continue to mature and are used in increasingly demanding situations, it is critical to develop a fundamental understanding of how robust these materials are. One of the most important factors to quantify is how much acid is photogenerated in these systems at key exposure doses. For the purpose of quantifying photoacid generation several methods have been devised. These include spectrophotometric methods, ion conductivity methods and most recently an acid-base type titration similar to the standard addition method. This paper compares many of these techniques. First, comparisons between the most commonly used acid sensitive dye, tetrabromophenol blue sodium salt (TBPB) and a less common acid sensitive dye, Rhodamine B base (RB) are made in several resist systems. Second, the novel acid-base type titration based on the standard addition method is compared to the spectrophotometric titration method. During these studies, the make up of the resist system is probed as follows: the photoacid generator and resist additives are varied to understand the impact of each of these resist components on the acid generation process.

Native ESI Mass Spectrometry Can Help to Avoid Wrong Interpretations from Isothermal Titration Calorimetry in Difficult Situations

NASA Astrophysics Data System (ADS)

Wolff, Philippe; Da Veiga, Cyrielle; Ennifar, Eric; Bec, Guillaume; Guichard, Gilles; Burnouf, Dominique; Dumas, Philippe

2017-02-01

We studied by native ESI-MS the binding of various DNA-polymerase-derived peptides onto DNA-polymerase processivity rings from Escherichia coli, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. These homodimeric rings present two equivalent specific binding sites, which leads to successive formation during a titration experiment of singly- and doubly occupied rings. By using the ESI-MS free-ring spectrum as a ruler, we derived by robust linear regression the fractions of the different ring species at each step of a titration experiment. These results led to accurate Kd values (from 0.03 to 0.5 μM) along with the probability of peptide loss due to gas phase dissociation (GPD). We show that this good quality is due to the increased information content of a titration experiment with a homodimer. Isothermal titration calorimetry (ITC) led with the same binding model to Kd(ITC) values systematically higher than their ESI-MS counterparts and, often, to poor fit of the ITC curves. A processing with two competing modes of binding on the same site requiring determination of two (Kd, ΔH) pairs greatly improved the fits and yielded a second Kd(ITC) close to Kd(ESI-MS). The striking features are: (1) ITC detected a minor binding mode ( 20%) of `low-affinity' that did not appear with ESI-MS; (2) the simplest processing of ITC data with only one (Kd, ΔH) pair led wrongly to the Kd of the low-affinity binding mode but to the ΔH of the high-affinity binding mode. Analogous misleading results might well exist in published data based on ITC experiments.

Native ESI Mass Spectrometry Can Help to Avoid Wrong Interpretations from Isothermal Titration Calorimetry in Difficult Situations.

PubMed

Wolff, Philippe; Da Veiga, Cyrielle; Ennifar, Eric; Bec, Guillaume; Guichard, Gilles; Burnouf, Dominique; Dumas, Philippe

2017-02-01

We studied by native ESI-MS the binding of various DNA-polymerase-derived peptides onto DNA-polymerase processivity rings from Escherichia coli, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. These homodimeric rings present two equivalent specific binding sites, which leads to successive formation during a titration experiment of singly- and doubly occupied rings. By using the ESI-MS free-ring spectrum as a ruler, we derived by robust linear regression the fractions of the different ring species at each step of a titration experiment. These results led to accurate K d values (from 0.03 to 0.5 μM) along with the probability of peptide loss due to gas phase dissociation (GPD). We show that this good quality is due to the increased information content of a titration experiment with a homodimer. Isothermal titration calorimetry (ITC) led with the same binding model to K d (ITC) values systematically higher than their ESI-MS counterparts and, often, to poor fit of the ITC curves. A processing with two competing modes of binding on the same site requiring determination of two (K d , ΔH) pairs greatly improved the fits and yielded a second K d (ITC) close to K d (ESI-MS). The striking features are: (1) ITC detected a minor binding mode (~20%) of 'low-affinity' that did not appear with ESI-MS; (2) the simplest processing of ITC data with only one (K d , ΔH) pair led wrongly to the Kd of the low-affinity binding mode but to the ΔH of the high-affinity binding mode. Analogous misleading results might well exist in published data based on ITC experiments. Graphical Abstract ᅟ.

Home blood pressure monitoring and self-titration of antihypertensive medications: Proposed patient selection criteria.

PubMed

Hill, James R

2016-05-01

Recent studies have demonstrated that home blood pressure monitoring (HBPM), coupled with self-titration of medications is a viable intervention to control hypertension. There are currently no established criteria to evaluate patients for inclusion in such a program. The purpose of this discussion is to propose criteria for determining if a patient is appropriate to participate in a program of HBPM and self-titration. Inclusion criteria for two self-titration trials were examined, and additional factors in clinical practice were identified and discussed. Additional selection criteria were proposed to support the decision to enroll a patient in an antihypertensive self-titration program. Inclusion criteria from self-titration trials provide a reasonable starting point for choosing appropriate patients in clinical practice, but additional research is necessary. Adaptation of these criteria and consideration of the identified factors can be used to develop decision support instruments. Such instruments should be evaluated for effectiveness and reliability prior to use in clinical practice. HBPM combined with self-titration is an effective patient-centered approach for hypertension management. Decision support instruments to determine appropriate patients are necessary for safe and effective use in clinical practice. ©2015 American Association of Nurse Practitioners.

Thermometric titrations of amines with nitrosyl perchlorate in acetonitrile solvent.

PubMed

Gündüz, T; Kiliç, E; Cakirer, O

1996-05-01

Thirteen aliphatic and four aromatic amines, namely diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-butylamine, isopropylamine, di-isopropylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, aniline, N,N-dimethylaniline, 2-nitroaniline and 4-nitroaniline were titrated thermometrically with nitrosyl perchlorate in acetonitrile solvent. All the aliphatic amines gave very well-shaped thermometric titration curves. The calculated recovery values of the amines were very good. In comparison, the aromatic amines, aniline and N,N-dimethylaniline gave rather well-shaped titration curves, but the recovery values were fairly low. 2-Nitro- and 4-nitro anilines gave no thermometric response at all. The heats of reaction of the amines with nitrosyl perchlorate are rather high. However, the average heat of reaction of the aromatic amines is approximately two-thirds that of the average heat of the aliphatic amines. To support this method all the amines were also titrated potentiometrically and very similar results to those obtained with the thermometric method are seen. The nitrosyl ion is a Lewis acid, strong enough to titrate quantitatively aliphatic amines in acetonitrile solvent, but not strong enough to titrate aromatic amines at the required level in the same solvent.

Assessment of residual active chlorine in sodium hypochlorite solutions after dissolution of porcine incisor pulpal tissue.

PubMed

Clarkson, R M; Smith, T K; Kidd, B A; Evans, G E; Moule, A J

2013-12-01

In previous studies, surfactant-containing Hypochlor brands of sodium hypochlorite showed better tissue solubilizing abilities than Milton; differences not explained by original active chlorine content or presence of surfactant. It was postulated that exhaustion of active chlorine content could explain differences. This study aimed to assess whether Milton's poorer performance was due to exhaustion of active chlorine. Parallel experiments assessed the influence of titration methods, and the presence of chlorates, on active chlorine measurements. Time required to dissolve one or groups of 10 samples of porcine incisor pulp samples in Milton was determined. Residual active chlorine was assessed by thermometric titration. Iodometric and thermometric titration was carried out on samples of Milton. Chlorate content was also measured. Dissolution of single and 10 pulp samples caused a mean loss of 1% and 3% respectively of active chlorine, not being proportional to tissue dissolved. Thermometric ammonium ion titration resulted in 10% lower values than iodometric titration. Chlorate accounted for much of this difference. Depletion of active chlorine is not the reason for differences in tissue dissolving capabilities of Milton. Thermometric ammonium ion titration gives more accurate measurement of active chlorine content than iodometric titration. © 2013 Australian Dental Association.

Acid-base titrations of functional groups on the surface of the thermophilic bacterium Anoxybacillus flavithermus: comparing a chemical equilibrium model with ATR-IR spectroscopic data.

PubMed

Heinrich, Hannah T M; Bremer, Phil J; Daughney, Christopher J; McQuillan, A James

2007-02-27

Acid-base functional groups at the surface of Anoxybacillus flavithermus (AF) were assigned from the modeling of batch titration data of bacterial suspensions and compared with those determined from in situ infrared spectroscopic titration analysis. The computer program FITMOD was used to generate a two-site Donnan model (site 1: pKa = 3.26, wet concn = 2.46 x 10(-4) mol g(-1); site 2: pKa = 6.12, wet concn = 6.55 x 10(-5) mol g(-1)), which was able to describe data for whole exponential phase cells from both batch acid-base titrations at 0.01 M ionic strength and electrophoretic mobility measurements over a range of different pH values and ionic strengths. In agreement with information on the composition of bacterial cell walls and a considerable body of modeling literature, site 1 of the model was assigned to carboxyl groups, and site 2 was assigned to amino groups. pH difference IR spectra acquired by in situ attenuated total reflection infrared (ATR-IR) spectroscopy confirmed the presence of carboxyl groups. The spectra appear to show a carboxyl pKa in the 3.3-4.0 range. Further peaks were assigned to phosphodiester groups, which deprotonated at slightly lower pH. The presence of amino groups could not be confirmed or discounted by IR spectroscopy, but a positively charged group corresponding to site 2 was implicated by electrophoretic mobility data. Carboxyl group speciation over a pH range of 2.3-10.3 at two different ionic strengths was further compared to modeling predictions. While model predictions were strongly influenced by the ionic strength change, pH difference IR data showed no significant change. This meant that modeling predictions agreed reasonably well with the IR data for 0.5 M ionic strength but not for 0.01 M ionic strength.

pH-metric solubility. 2: correlation between the acid-base titration and the saturation shake-flask solubility-pH methods.

PubMed

Avdeef, A; Berger, C M; Brownell, C

2000-01-01

The objective of this study was to compare the results of a normal saturation shake-flask method to a new potentiometric acid-base titration method for determining the intrinsic solubility and the solubility-pH profiles of ionizable molecules, and to report the solubility constants determined by the latter technique. The solubility-pH profiles of twelve generic drugs (atenolol, diclofenac.Na, famotidine, flurbiprofen, furosemide, hydrochlorothiazide, ibuprofen, ketoprofen, labetolol.HCl, naproxen, phenytoin, and propranolol.HCl), with solubilities spanning over six orders of magnitude, were determined both by the new pH-metric method and by a traditional approach (24 hr shaking of saturated solutions, followed by filtration, then HPLC assaying with UV detection). The 212 separate saturation shake-flask solubility measurements and those derived from 65 potentiometric titrations agreed well. The analysis produced the correlation equation: log(1/S)titration = -0.063(+/- 0.032) + 1.025(+/- 0.011) log(1/S)shake-flask, s = 0.20, r2 = 0.978. The potentiometrically-derived intrinsic solubilities of the drugs were: atenolol 13.5 mg/mL, diclofenac.Na 0.82 microg/mL, famotidine 1.1 mg/ mL, flurbiprofen 10.6 microg/mL, furosemide 5.9 microg/mL, hydrochlorothiazide 0.70 mg/mL, ibuprofen 49 microg/mL, ketoprofen 118 microg/mL, labetolol.HCl 128 microg/mL, naproxen 14 microg/mL, phenytoin 19 microg/mL, and propranolol.HCl 70 microg/mL. The new potentiometric method was shown to be reliable for determining the solubility-pH profiles of uncharged ionizable drug substances. Its speed compared to conventional equilibrium measurements, its sound theoretical basis, its ability to generate the full solubility-pH profile from a single titration, and its dynamic range (currently estimated to be seven orders of magnitude) make the new pH-metric method an attractive addition to traditional approaches used by preformulation and development scientists. It may be useful even to discovery scientists in critical decision situations (such as calibrating computational prediction methods).

The Potentiometric Titration of Filtrates from the Bachmann Process

DTIC Science & Technology

1942-06-23

SCIENTIFIC RESEARCH AND DEVELOP11ENT The Potentiometric Titration of Filtrates from the Bachmann Process (OD-12) by F. C. Whitmore OSRD No. 654... Potentiometric Titration of Synthetic Mixtures. A? Nitric Acid-Acetic Acid. A sample of 60 ml. glacial acetic acid war diluted to 200 ml. with distilled...i4flinflr?fj3 TADLE 1 CO) |S?lDBnTl» POTENTIOMETRIC TITRATION OF SYNTHETIC t’.IXTURES WITH CONCENTRATED AJKDNIUM HYDROXIDE A; unonium HNO-j- AcOfi Ky

Quantitative Determination of NTA and Other Chelating Agents in Detergents by Potentiometric Titration with Copper Ion Selective Electrode.

PubMed

Ito, Sana; Morita, Masaki

2016-01-01

Quantitative analysis of nitrilotriacetate (NTA) in detergents by titration with Cu 2+ solution using a copper ion selective electrode was achieved. This method tolerates a wide range of pH and ingredients in detergents. In addition to NTA, other chelating agents, having relatively lower stability constants toward Cu 2+ , were also qualified with sufficient accuracy by this analytical method for model detergent formulations. The titration process was automated by automatic titrating systems available commercially.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauli, Adam T; Robertson, Raymond E; Branthaver, Jan F

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.

A supramolecular miktoarm star polymer based on porphyrin metal complexation in water.

PubMed

Hou, Zhanyao; Dehaen, Wim; Lyskawa, Joël; Woisel, Patrice; Hoogenboom, Richard

2017-07-25

A novel supramolecular miktoarm star polymer was successfully constructed in water from a pyridine end-decorated polymer (Py-PmDEGA) and a metalloporphyrin based star polymer (ZnTPP-(PEG) 4 ) via metal-ligand coordination. The Py-PmDEGA moiety was prepared via a combination of reversible addition-fragmentation chain transfer polymerization (RAFT) and subsequent aminolysis and Michael addition reactions to introduce the pyridine end-group. The ZnTPP(PEG) 4 star-polymer was synthesized by the reaction between tetrakis(p-hydroxyphenyl)porphyrin and toluenesulfonyl-PEG, followed by insertion of a zinc ion into the porphyrin core. The formation of a well-defined supramolecular AB 4 -type miktoarm star polymer was unambiguously demonstrated via UV-Vis spectroscopic titration, isothermal titration calorimetry (ITC) and diffusion ordered NMR spectroscopy (DOSY).

Value of routine investigations to predict loop diuretic down-titration success in stable heart failure.

PubMed

Martens, Pieter; Verbrugge, Frederik H; Boonen, Levinia; Nijst, Petra; Dupont, Matthias; Mullens, Wilfried

2018-01-01

Guidelines advocate down-titration of loop diuretics in chronic heart failure (CHF) when patients have no signs of volume overload. Limited data are available on the expected success rate of this practice or how routine diagnostic tests might help steering this process. Fifty ambulatory CHF-patients on stable neurohumoral blocker/diuretic therapy for at least 3months without any clinical sign of volume overload were prospectively included to undergo loop diuretic down-titration. All patients underwent a similar pre-down-titration evaluation consisting of a dyspnea scoring, physical examination, transthoracic echocardiography (diastolic function, right ventricular function, cardiac filling pressures and valvular disease), blood sample (serum creatinine, plasma NT-pro-BNP and neurohormones). Loop diuretic maintenance dose was subsequently reduced by 50% or stopped if dose was ≤40mg furosemide equivalents. Successful down-titration was defined as a persistent dose reduction after 30days without weight increase >1.5kg or new-onset symptoms of worsening heart failure. At 30-day follow-up, down-titration was successful in 62% (n=31). In 12/19 patients exhibiting down-titration failure, this occurred within the first week. Physical examination, transthoracic echocardiography and laboratory analysis had limited predictive capability to detect patients with down-titration success/failure (positive likelihood-ratios below 1.5, or area under the curve [AUC] non-statically different from AUC=0.5). Loop diuretic down-titration is feasible in a majority of stable CHF patients in which the treating clinician felt continuation of loops was unnecessary to sustain euvolemia. Importantly, routine diagnostics which suggest euvolemia, have limited diagnostic impact on the post-test probability. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of positive end-expiratory pressure titration and recruitment maneuver on lung inflammation and hyperinflation in experimental acid aspiration-induced lung injury.

PubMed

Ambrosio, Aline M; Luo, Rubin; Fantoni, Denise T; Gutierres, Claudia; Lu, Qin; Gu, Wen-Jie; Otsuki, Denise A; Malbouisson, Luiz M S; Auler, Jose O C; Rouby, Jean-Jacques

2012-12-01

In acute lung injury positive end-expiratory pressure (PEEP) and recruitment maneuver are proposed to optimize arterial oxygenation. The aim of the study was to evaluate the impact of such a strategy on lung histological inflammation and hyperinflation in pigs with acid aspiration-induced lung injury. Forty-seven pigs were randomly allocated in seven groups: (1) controls spontaneously breathing; (2) without lung injury, PEEP 5 cm H2O; (3) without lung injury, PEEP titration; (4) without lung injury, PEEP titration + recruitment maneuver; (5) with lung injury, PEEP 5 cm H2O; (6) with lung injury, PEEP titration; and (7) with lung injury, PEEP titration + recruitment maneuver. Acute lung injury was induced by intratracheal instillation of hydrochloric acid. PEEP titration was performed by incremental and decremental PEEP from 5 to 20 cm H2O for optimizing arterial oxygenation. Three recruitment maneuvers (pressure of 40 cm H2O maintained for 20 s) were applied to the assigned groups at each PEEP level. Proportion of lung inflammation, hemorrhage, edema, and alveolar wall disruption were recorded on each histological field. Mean alveolar area was measured in the aerated lung regions. Acid aspiration increased mean alveolar area and produced alveolar wall disruption, lung edema, alveolar hemorrhage, and lung inflammation. PEEP titration significantly improved arterial oxygenation but simultaneously increased lung inflammation in juxta-diaphragmatic lung regions. Recruitment maneuver during PEEP titration did not induce additional increase in lung inflammation and alveolar hyperinflation. In a porcine model of acid aspiration-induced lung injury, PEEP titration aimed at optimizing arterial oxygenation, substantially increased lung inflammation. Recruitment maneuvers further improved arterial oxygenation without additional effects on inflammation and hyperinflation.

Impact of hypoglycemic events and HbA1c level on sulfonylurea discontinuation and down-titration.

PubMed

Laires, Pedro A; Tang, Jackson; Fan, Chun Po Steve; Li, Zhiyi; Qiu, Ying; Iglay, Kristy

2017-04-01

A retrospective cohort study using GE Centricity electronic medical records assessed the association between post-index hypoglycemia and HbA1c with discontinuation and down-titration of sulfonylureas among patients with Type 2 diabetes mellitus. Adult patients with an index prescription for a sulfonylurea and ≥12 months' continuous records pre- and post-index were eligible. Sulfonylurea discontinuation and down-titration was assessed 1-year post-index. Discontinuation occurred if the date of a prescription was >90 days from the preceding prescription plus days of supply. Down-titration occurred when a subsequent prescription was lower than the index dose. Cox regression assessed the association between post-index hypoglycemia and HbA1c with time to sulfonylurea discontinuation and down-titration, as well as other factors. 28,371 participants were included in the study; 13,459 (47.4%) were discontinuers, 717 (2.5%) were down-titraters, and 14,195 (50.0%) were continuers. 0.6% of continuers experienced hypoglycemia 1-year post-index, compared with 3.1% of down-titraters and 0.8% of discontinuers (p < 0.0001). Patients with post-index hypoglycemia had a significantly higher rate of discontinuation (hazard ratio [HR] = 1.82, 95% CI: 1.47-2.23) and down-titration (HR = 4.25, 95% CI: 1.92-8.03). Patients with higher post-index HbA1c and use of 2 nd generation sulfonylureas had an increased rate of discontinuation (HR = 1.05, 95% CI: 1.04-1.06; HR = 1.19, 95% CI: 1.14-1.24, respectively). Approximately half of participants who initiated sulfonylureas discontinued or down-titrated therapy within one year. Both post-index hypoglycemia and higher HbA1c were significant risk factors for sulfonylurea treatment change.

Temperature effect on the acid-base behaviour of Na-montmorillonite.

PubMed

Duc, Myriam; Carteret, Cédric; Thomas, Fabien; Gaboriaud, Fabien

2008-11-15

We report a study of the acid-base properties of Na-montmorillonite suspensions at temperatures from 25 degrees C to 80 degrees C, by continuous and batch potentiometric methods, combined with analysis of the dissolved and readsorbed species. The batch titration curves reveal that the dissolution processes of Na-montmorillonite and silica-rich secondary phases are increasingly predominant, respectively at acid and basic pH, and according to the temperature. The continuous titration curves are less affected by these side reactions. In the absence of a common intersection point, the thermodynamic analysis of the curves was based on the shift of the PZNPC with the ionic strength. This shift was not significantly altered by the temperature, by comparison with the dissociation product of water in the same conditions. Therefore we concluded that protonation-deprotonation of the dissociable sites at the edges of the clay platelets is not significantly temperature dependent.

Highly accurate nephelometric titrimetry.

PubMed

Zhan, Xiancheng; Li, Chengrong; Li, Zhiyi; Yang, Xiucen; Zhong, Shuguang; Yi, Tao

2004-02-01

A method that accurately indicates the end-point of precipitation reactions by the measurement of the relative intensity of the scattered light in the titrate is presented. A new nephelometric titrator with an internal nephelometric sensor has been devised. The work of the titrator including the sensor and change in the turbidity of the titrate and intensity of the scattered light are described. The accuracy of the nephelometric titrimetry is discussed theoretically. The titration of NaCl with AgNO(3) serves as a model. A relative error as well as deviation is within 0.2% under the experimental conditions. The applicability of the titrimetry in pharmaceutical analyses, for example, phenytoin sodium and procaine hydrochloride, is generally illustrated. Copyright 2004 Wiley-Liss, Inc. and the American Pharmacists Association

Microtitration of various anions with quaternary ammonium halides using solid-state electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selig, W.

1980-01-01

Many solid-state electrodes were found to respond as endpoint detectors in the potentiometric titration of large inorganic and organic anions with quaternary ammonium halides. The best response was obtained with the iodide and cyanide electrodes although practically any electrode can function as endpoint sensor. The titrants were hexadecylpyridinium chloride and hexadecyltrimethylammonium chloride; hexadecyltrimethylammonium bromide and Hyamine 1622 may also be used. Some inorganic anions thus titratable are perrhenate, persulfate, ferricyanide, hexafluorophosphate, and hexachloroplatinate. Examples of organic anions titratable are nitroform, tetraphenylborate, cyanotriphenylborate, picrate, long-chain sulfates and sulfonates, and some soaps. The reverse titration of quaternary ammonium halides vs dodecylsulfate ismore » also feasible. Some titrations are feasible in a partially nonaqueous medium.« less

Symmetry Properties of Potentiometric Titration Curves.

ERIC Educational Resources Information Center

Macca, Carlo; Bombi, G. Giorgio

1983-01-01

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)

A Tabular Approach to Titration Calculations

ERIC Educational Resources Information Center

Lim, Kieran F.

2012-01-01

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

LIGHT TITRATIONS

PubMed Central

Field, John; Baas-Becking, Lourens G. M.

1926-01-01

1. The usefulness of the radiomicrometer in titration work has been pointed out. The authors suggest that light titration may also be used where a reaction mixture changes its absorption in the (near) infra-red. 2. The applicability of this method to the starch-iodine reaction has been demonstrated. PMID:19872266

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Guoping; Luo, Wensui; Brooks, Scott C

We conducted batch and recirculating column titration tests with contaminated acidic sediments with controlled CO2 in the headspace, and extended the geochemical model by Gu et al. (2003, GCA) to better understand and quantify the reactions governing trace metal fate in the subsurface. The sediment titration curve showed slow pH increase due to strong buffering by Al precipitation and CO2 uptake. Assuming precipitation of basaluminite at low saturation index (SI=-4), and decreasing cation exchange selectivity coefficient (kNa\\Al=0.3), the predictions are close to the observed pH and Al; and the model explains 1) the observed Ca, Mg, and Mn concentration decreasemore » by cation exchange with sorbed Al, and 2) the decrease of U by surface complexation with Fe hydroxides at low pH, and precipitation as liebigite (Ca2UO2(CO3)3:10H2O) at pH>5.5. Without further adjustment geochemical parameters, the model describes reasonably well previous sediment and column titration tests without CO2 in the headspace, as well as the new large column test. The apparent inhibition of U and Ni decrease in the large column can be explained by formation of aqueous carbonate complexes and/or competition with carbonate for surface sites. These results indicated that ignoring labile solid phase Al would underestimate base requirement in titration of acidic aquifers.« less

Antiepileptic Drug Titration and Related Health Care Resource Use and Costs.

PubMed

Fishman, Jesse; Kalilani, Linda; Song, Yan; Swallow, Elyse; Wild, Imane

2018-02-27

Unexpected breakthrough seizures resulting from suboptimal antiepileptic drug (AED) dosing during the titration period, as well as adverse events resulting from rapid AED titration, may influence the titration schedule and significantly increase health care resource use (HRU) and health care costs. To assess the relationship between AEDs, HRU, and costs during AED titration and maintenance. Practicing neurologists were recruited from a nationwide panel to provide up to 3 patient records each for this retrospective medical chart review. Patients with epilepsy who were aged ≥ 18 years and had initiated an AED between January 1, 2014, and January 1, 2016, were followed for 6 months from AED initiation. Titration duration was the time from AED initiation to the beginning of treatment maintenance as determined by the physician. Outcomes were epilepsy-specific HRU (hospitalizations, emergency department visits, outpatient visits, physician referral, laboratory testing/diagnostic imaging, and phone calls) and related costs that occurred during the titration or maintenance treatment periods. Of 811 patients, 156, 128, 125, 120, 114, 107, and 61 initiated the following AEDs: levetiracetam, lamotrigine, lacosamide, valproate, topiramate, carbamazepine, and phenytoin, respectively. Most patients (619/803 [77.1%] with complete AED data) received monotherapy. Baseline characteristics were similar across AEDs (mean [SD] age, 36.6 [14.4] years; 59.0% male). Kaplan-Meier estimates of titration duration ranged from 3.3 weeks (phenytoin) to 8.1 weeks (lamotrigine). From titration to maintenance, the overall incidence of HRU per person-month decreased 54.5%-89.3% for each HRU measure except outpatient visits (24.6% decrease). Total epilepsy-related costs decreased from $80.48 to $42.77 per person-month, or 46.9% from titration to maintenance. AED titration periods had higher HRU rates and costs than AED maintenance, suggesting that use of AEDs with shorter titration requirements reduces health care costs, although disease severity may also factor into overall cost. UCB Pharma sponsored this study and reviewed the manuscript. Fishman and Kalilani are employees of UCB Pharma. Wild was an employee of UCB Pharma at the time this analysis was conducted. Song and Swallow are employees of Analysis Group, which received funding from UCB Pharma. Study concept and design were contributed by Fishman, Kalilani, and Wild, along with other authors. Data collection was performed by Song and Swallow. All authors contributed to data interpretation. Writing of the manuscript was led by Fishman, Song, and Swallow, with revisions by all authors.

Simultaneous determination of thermodynamic and kinetic parameters of aminopolycarbonate complexes of cobalt(II) and nickel(II) based on isothermal titration calorimetry data.

PubMed

Tesmar, Aleksandra; Wyrzykowski, Dariusz; Muñoz, Eva; Pilarski, Bogusław; Pranczk, Joanna; Jacewicz, Dagmara; Chmurzyński, Lech

2017-04-01

The influence of the different side chain residues on the thermodynamic and kinetic parameters for complexation reactions of the Co 2 + and Ni 2 + ions has been investigated by using the isothermal titration calorimetry (ITC) technique supported by potentiometric titration data. The study was concerned with the 2 common tripodal aminocarboxylate ligands, namely, nitrilotriacetic acid and N-(2-hydroxyethyl) iminodiacetic acid. Calorimetric measurements (ITC) were run in the 2-(N-morpholino)ethanesulfonic acid hydrate (2-(N-morpholino) ethanesulfonic acid), piperazine-N,N'-bis(2-ethanesulfonic acid), and dimethylarsenic acid buffers (0.1 mol L -1 , pH 6) at 298.15 K. The quantification of the metal-buffer interactions and their incorporation into the ITC data analysis enabled to obtain the pH-independent and buffer-independent thermodynamic parameters (K, ΔG, ΔH, and ΔS) for the reactions under study. Furthermore, the kinITC method was applied to obtain kinetic information on complexation reactions from the ITC data. Correlations, based on kinetic and thermodynamic data, between the kinetics of formation of Co 2 + and Ni 2 + complexes and their thermodynamic stabilities are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Solid State Sensor for Simultaneous Measurement of Total Alkalinity and pH of Seawater.

PubMed

Briggs, Ellen M; Sandoval, Sergio; Erten, Ahmet; Takeshita, Yuichiro; Kummel, Andrew C; Martz, Todd R

2017-09-22

A novel design is demonstrated for a solid state, reagent-less sensor capable of rapid and simultaneous measurement of pH and Total Alkalinity (A T ) using ion sensitive field effect transistor (ISFET) technology to provide a simplified means of characterization of the aqueous carbon dioxide system through measurement of two "master variables": pH and A T . ISFET-based pH sensors that achieve 0.001 precision are widely used in various oceanographic applications. A modified ISFET is demonstrated to perform a nanoliter-scale acid-base titration of A T in under 40 s. This method of measuring A T , a Coulometric Diffusion Titration, involves electrolytic generation of titrant, H + , through the electrolysis of water on the surface of the chip via a microfabricated electrode eliminating the requirement of external reagents. Characterization has been performed in seawater as well as titrating individual components (i.e., OH - , HCO 3 - , CO 3 2- , B(OH) 4 - , PO 4 3- ) of seawater A T . The seawater measurements are consistent with the design in reaching the benchmark goal of 0.5% precision in A T over the range of seawater A T of ∼2200-2500 μmol kg -1 which demonstrates great potential for autonomous sensing.

Absolute determination of single-stranded and self-complementary adeno-associated viral vector genome titers by droplet digital PCR.

PubMed

Lock, Martin; Alvira, Mauricio R; Chen, Shu-Jen; Wilson, James M

2014-04-01

Accurate titration of adeno-associated viral (AAV) vector genome copies is critical for ensuring correct and reproducible dosing in both preclinical and clinical settings. Quantitative PCR (qPCR) is the current method of choice for titrating AAV genomes because of the simplicity, accuracy, and robustness of the assay. However, issues with qPCR-based determination of self-complementary AAV vector genome titers, due to primer-probe exclusion through genome self-annealing or through packaging of prematurely terminated defective interfering (DI) genomes, have been reported. Alternative qPCR, gel-based, or Southern blotting titering methods have been designed to overcome these issues but may represent a backward step from standard qPCR methods in terms of simplicity, robustness, and precision. Droplet digital PCR (ddPCR) is a new PCR technique that directly quantifies DNA copies with an unparalleled degree of precision and without the need for a standard curve or for a high degree of amplification efficiency; all properties that lend themselves to the accurate quantification of both single-stranded and self-complementary AAV genomes. Here we compare a ddPCR-based AAV genome titer assay with a standard and an optimized qPCR assay for the titration of both single-stranded and self-complementary AAV genomes. We demonstrate absolute quantification of single-stranded AAV vector genomes by ddPCR with up to 4-fold increases in titer over a standard qPCR titration but with equivalent readout to an optimized qPCR assay. In the case of self-complementary vectors, ddPCR titers were on average 5-, 1.9-, and 2.3-fold higher than those determined by standard qPCR, optimized qPCR, and agarose gel assays, respectively. Droplet digital PCR-based genome titering was superior to qPCR in terms of both intra- and interassay precision and is more resistant to PCR inhibitors, a desirable feature for in-process monitoring of early-stage vector production and for vector genome biodistribution analysis in inhibitory tissues.

Effects of Epoetin Alfa Titration Practices, Implemented After Changes to Product Labeling, on Hemoglobin Levels, Transfusion Use, and Hospitalization Rates.

PubMed

Molony, Julia T; Monda, Keri L; Li, Suying; Beaubrun, Anne C; Gilbertson, David T; Bradbury, Brian D; Collins, Allan J

2016-08-01

Little is known about epoetin alfa (EPO) dosing at dialysis centers after implementation of the US Medicare prospective payment system and revision of the EPO label in 2011. Retrospective cohort study. Approximately 412,000 adult hemodialysis patients with Medicare Parts A and B as primary payer in 2009 to 2012 to describe EPO dosing and hemoglobin patterns; of these, about 70,000 patients clustered in about 1,300 dialysis facilities to evaluate facility-level EPO titration practices and patient-level outcomes in 2012. Facility EPO titration practices when hemoglobin levels were <10 and >11g/dL (grouped treatment variable) determined from monthly EPO dosing and hemoglobin level patterns. Patient mean hemoglobin levels, red blood cell transfusion rates, and all-cause and cause-specific hospitalization rates using a facility-based analysis. Monthly EPO dose and hemoglobin level, red blood cell transfusion rates, and all-cause and cause-specific hospitalization rates. Monthly EPO doses declined across all hemoglobin levels, with the greatest decline in patients with hemoglobin levels < 10g/dL (July-October 2011). In 2012, nine distinct facility titration practices were identified. Across groups, mean hemoglobin levels differed slightly (10.5-10.8g/dL) but within-patient hemoglobin standard deviations were similar (∼0.68g/dL). Patients at facilities implementing greater dose reductions and smaller dose escalations had lower hemoglobin levels and higher transfusion rates. In contrast, patients at facilities that implemented greater dose escalations (and large or small dose reductions) had higher hemoglobin levels and lower transfusion rates. There were no clinically meaningful differences in all-cause or cause-specific hospitalization events across groups. Possibly incomplete claims data; excluded small facilities and those without consistent titration patterns; hemoglobin levels reported monthly; inferred facility practice from observed dosing. Following prospective payment system implementation and labeling revisions, EPO doses declined significantly. Under the new label, facility EPO titration practices were associated with mean hemoglobin levels (but not standard deviations) and transfusion use, but not hospitalization rates. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Application of Computers for Experiment Design, Data Acquisition, and Analysis in the Chemistry Laboratory

DTIC Science & Technology

1990-05-01

Obtain Thermistor Operating Characteristics ................................. 82 25. Ag+/Ci" Thermometric Titration ........................... 85 26...Experiment Program for Thermometric Titrations ............... 85 27. Appearance of the Spreadsheet in the Analysis Mode ............ 86 28...rate experiments, carbon dioxide exhalation monitoring, stream turbidity measurement, photosynthesis monitoring, pendulum timing, thermometric titrations

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

NASA Astrophysics Data System (ADS)

Villela, R. L. A.; Borges, P. P.; Vyskočil, L.

2015-01-01

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

Automatic photometric titrations of calcium and magnesium in carbonate rocks

USGS Publications Warehouse

Shapiro, L.; Brannock, W.W.

1955-01-01

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

Overall Survival Analysis From a Randomized Phase II Study of Axitinib With or Without Dose Titration in First-Line Metastatic Renal Cell Carcinoma.

PubMed

Rini, Brian I; Tomita, Yoshihiko; Melichar, Bohuslav; Ueda, Takeshi; Grünwald, Viktor; Fishman, Mayer N; Uemura, Hirotsugu; Oya, Mototsugu; Bair, Angel H; Andrews, Glen I; Rosbrook, Brad; Jonasch, Eric

2016-12-01

In a randomized phase II trial in metastatic renal cell carcinoma (mRCC), objective response rate was significantly higher with axitinib versus placebo titration (54% vs. 34%; 1-sided P = .019). Treatment-naive patients with mRCC (n = 213) received axitinib 5 mg twice per day (b.i.d.) for 4 weeks. Patients meeting dose titration criteria were randomized to receive axitinib 5 mg b.i.d. with axitinib or placebo titration (n = 56 each); 91 patients ineligible for randomization continued axitinib 5 mg b.i.d.; 10 discontinued before randomization. Median overall survival (95% confidence interval [CI]) was 42.7 months (24.7-not estimable) with axitinib titration versus 30.4 months (23.7-45.0) with placebo titration (stratified hazard ratio, 0.785; 95% CI, 0.485-1.272; 1-sided P = .162), and 41.6 months (95% CI, 33.0-not estimable) in nonrandomized patients. Safety data were consistent with previous reports. Median overall survival was numerically longer in patients with first-line mRCC who received axitinib versus placebo titration. No new safety signal was observed after long-term axitinib treatment in first-line mRCC. Copyright © 2016 Elsevier Inc. All rights reserved.

A 24-Week, Randomized, Controlled Study to Evaluate the Tolerability, Safety and Efficacy of 2 Different Titration Schemes of the Rivastigmine Patch in Japanese Patients with Mild to Moderate Alzheimer's Disease.

PubMed

Nakamura, Yu; Strohmaier, Christine; Tamura, Kaoru; Kataoka, Naoko; Nakano, Masayuki; Oda, Shoichiro; Nishimura, Kazuma; Homma, Akira

2015-01-01

To investigate whether 1-step titration of the rivastigmine patch (initiated at 5 cm(2) and titrated to 10 cm(2) after 4 weeks) is well tolerated in Japanese patients with Alzheimer's disease (AD) as compared to 3-step titration (initiated at 2.5 cm(2) and titrated by 2.5 cm(2) every 4 weeks to 10 cm(2)). A 24-week, multicenter, randomized, double-blind study was conducted in Japan between July 2012 and May 2014. Patients with mild to moderate AD aged 50-85 years were randomized 1:1 to 1-step or 3-step titration of the rivastigmine once-daily patch. The primary endpoint was the proportion of patients with adverse events leading to discontinuation. Of 216 patients randomized, 215 (1-step, n = 107; 3-step, n = 108) were included in the safety analysis. The primary endpoint outcome was 15.0% in the 1-step group and 18.5% in the 3-step group. The observed treatment difference was -3.6% (95% confidence interval: -17.0, 9.6), falling within the prespecified acceptance range. The tolerability of two different titration schemes was similar in Japanese patients with AD.

A 24-Week, Randomized, Controlled Study to Evaluate the Tolerability, Safety and Efficacy of 2 Different Titration Schemes of the Rivastigmine Patch in Japanese Patients with Mild to Moderate Alzheimer's Disease

PubMed Central

Nakamura, Yu; Strohmaier, Christine; Tamura, Kaoru; Kataoka, Naoko; Nakano, Masayuki; Oda, Shoichiro; Nishimura, Kazuma; Homma, Akira

2015-01-01

Aim To investigate whether 1-step titration of the rivastigmine patch (initiated at 5 cm2 and titrated to 10 cm2 after 4 weeks) is well tolerated in Japanese patients with Alzheimer's disease (AD) as compared to 3-step titration (initiated at 2.5 cm2 and titrated by 2.5 cm2 every 4 weeks to 10 cm2). Methods A 24-week, multicenter, randomized, double-blind study was conducted in Japan between July 2012 and May 2014. Patients with mild to moderate AD aged 50-85 years were randomized 1:1 to 1-step or 3-step titration of the rivastigmine once-daily patch. The primary endpoint was the proportion of patients with adverse events leading to discontinuation. Results Of 216 patients randomized, 215 (1-step, n = 107; 3-step, n = 108) were included in the safety analysis. The primary endpoint outcome was 15.0% in the 1-step group and 18.5% in the 3-step group. The observed treatment difference was −3.6% (95% confidence interval: −17.0, 9.6), falling within the prespecified acceptance range. Conclusion The tolerability of two different titration schemes was similar in Japanese patients with AD. PMID:26557135

Edible Acid-Base Indicators.

ERIC Educational Resources Information Center

Mebane, Robert C.; Rybolt, Thomas R.

1985-01-01

Reports on the colors observed during titrations of 15 natural indicators obtained from common fruits and vegetables. These edible indicators can be used for a variety of teacher demonstrations or for simple student experiments. (JN)

Improving Heart rate variability in sleep apnea patients: differences in treatment with auto-titrating positive airway pressure (APAP) versus conventional CPAP.

PubMed

Karasulu, Levent; Epöztürk, Pinar Ozkan; Sökücü, Sinem Nedime; Dalar, Levent; Altin, Sedat

2010-08-01

The effect of positive airway pressure treatments in different modalities on the cardiovascular consequences of the disease in sleep apnea patients is still unclear. We aimed to compare auto-titrating positive airway pressure (APAP) and conventional continuous positive airway pressure (CPAP) in terms of improving heart rate variability (HRV) in obstructive sleep apnea patients. This was a prospective study done in a tertiary research hospital. All patients underwent a manual CPAP titration procedure to determine the optimal pressure that abolishes abnormal respiratory events. Then patients underwent two treatment nights, one under APAP mode and one under conventional CPAP mode with a 1-week interval. Forty newly diagnosed obstructive sleep apnea patients were enrolled in the study. We compared heart rate variability analysis parameters between the APAP night and the CPAP night. This final analysis included the data of 28 patients (M/F: 22/6; mean age = 46 +/- 10 years). Sleep characteristics were comparable between the two treatment nights, whereas all-night time domains of HRV analysis such as HF, nuLF, and LF/HF were different between APAP and CPAP nights (2.93 +/- 0.31 vs. 3.01 +/- 0.31; P = 0.041; 0.75 +/- 0.13 vs. 0.71 +/- 0.14; P = 0.027; and 4.37 +/- 3.24 vs. 3.56 +/- 2.07; P = 0.023, respectively). HRV analysis for individual sleep stages showed that Stage 2 LF, nuLF, nuHF, LF/HF parameters entirely improved under CPAP treatment whereas APAP treatment resulted in nonsignificant changes. These results suggest that despite comparable improvement in abnormal respiratory events with APAP or CPAP treatments, CPAP may be superior to APAP in terms of correcting cardiovascular alterations in sleep apnea patients.

Oxygen titration after resuscitation from out-of-hospital cardiac arrest: A multi-centre, randomised controlled pilot study (the EXACT pilot trial).

PubMed

Bray, Janet E; Hein, Cindy; Smith, Karen; Stephenson, Michael; Grantham, Hugh; Finn, Judith; Stub, Dion; Cameron, Peter; Bernard, Stephen

2018-04-21

Recent studies suggest the administration of 100% oxygen to hyperoxic levels following return-of-spontaneous-circulation (ROSC) post-cardiac arrest may be harmful. However, the feasibility and safety of oxygen titration in the prehospital setting is unknown. We conducted a multi-centre, phase-2 study testing whether prehospital titration of oxygen results in an equivalent number of patients arriving at hospital with oxygen saturations SpO2 ≥ 94%. We enrolled unconscious adults with: sustained ROSC; initial shockable rhythm; an advanced airway; and an SpO2 ≥ 95%. Initially (Sept 2015-March 2016) patients were randomised 1:1 to either 2 L/minute (L/min) oxygen (titrated) or >10 L/min oxygen (control) via a bag-valve reservoir. However, one site experienced a high number of desaturations (SpO2 < 94%) in the titrated arm and this arm was changed (April 2016) to an initial reduction of oxygen to 4 L/min then, if tolerated, to 2 L/min, and the desaturation limit was decreased to <90%. We randomised 61 patients to titrated (n = 37: 2L/min = 20 and 2-4 L/min = 17) oxygen or control (n = 24). Patients allocated to titrated oxygen were more likely to desaturate compared to controls ((SpO2 < 94%: 43% vs. 4%, p = 0.001; SpO2 < 90%: 19% vs. 4%, p = 0.09). The majority of desaturations (81%) occurred at 2L/min. On arrival at hospital the majority of patients had a SpO2 ≥ 94% (titrated: 90% vs. control: 100%) and all patients had a SpO2 ≥ 90%. One patient (control) re-arrested. Survival to hospital discharge was similar. Oxygen titration post-ROSC is feasible in the prehospital environment, but incremental titration commencing at 4L/min oxygen flow may be needed to maintain an oxygen saturation >90% (NCT02499042). Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis for nickel (3 and 4) in positive plates from nickel-cadmium cells

NASA Technical Reports Server (NTRS)

Lewis, Harlan L.

1994-01-01

The NASA-Goddard procedure for destructive physical analysis (DPA) of nickel-cadmium cells contains a method for analysis of residual charged nickel as NiOOH in the positive plates at complete cell discharge, also known as nickel precharge. In the method, the Ni(III) is treated with an excess of an Fe(II) reducing agent and then back titrated with permanganate. The Ni(III) content is the difference between Fe(II) equivalents and permanganate equivalents. Problems have arisen in analysis at NAVSURFWARCENDIV, Crane because for many types of cells, particularly AA-size and some 'space-qualified' cells, zero or negative Ni(III) contents are recorded for which the manufacturer claims 3-5 percent precharge. Our approach to this problem was to reexamine the procedure for the source of error, and correct it or develop an alternative method.

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

PubMed

Pethica, Brian A

2015-03-01

Isothermal titration calorimetry (ITC) has given a mass of data on the binding of small molecules to proteins and other biopolymers, with particular interest in drug binding to proteins chosen as therapeutic indicators. Interpretation of the enthalpy data usually follows an unsound protocol that uses thermodynamic relations in circumstances where they do not apply. Errors of interpretation include incomplete definitions of ligand binding and equilibrium constants and neglect of the non-ideality of the solutions under study, leading to unreliable estimates of standard free energies and entropies of binding. The mass of reported thermodynamic functions for ligand binding to proteins estimated from ITC enthalpies alone is consequently of uncertain thermodynamic significance and utility. ITC and related experiments to test the protocol assumptions are indicated. A thermodynamic procedure avoiding equilibrium constants or other reaction models and not requiring protein activities is given. The discussion draws attention to the fundamental but neglected relation between the thermodynamic activity and bioactivity of drugs and to the generally unknown thermodynamic status of ligand solutions, which for drugs relates directly to effective therapeutic dosimetry. Copyright © 2014 Elsevier Inc. All rights reserved.

A method to rapidly and accurately compare relative efficacies of non-invasive imaging reporter genes in a mouse model, and its application to luciferase reporters

PubMed Central

Gil, Jose S.; Machado, Hidevaldo B.; Herschman, Harvey R.

2013-01-01

Purpose Our goal is to develop a simple, quantitative, robust method to compare the efficacy of imaging reporter genes in culture and in vivo. We describe an adenoviral vector-liver transduction procedure, and compare the luciferase reporter efficacies. Procedures Alternative reporter genes are expressed in a common adenoviral vector. Vector amounts used in vivo are based on cell culture titrations, ensuring the same transduction efficacy is used for each vector. After imaging, in vivo and in vitro values are normalized to hepatic vector transduction using quantitative real-time PCR. Results We assayed standard firefly luciferase (FLuc), enhanced firefly luciferase (EFLuc), luciferase 2 (Luc2), humanized Renilla luciferase (hRLuc), Renilla luciferase 8.6-535 (RLuc8.6), and a membrane-bound Gaussia luciferase variant (extGLuc) in cell culture and in vivo. We observed a greater that 100-fold increase in bioluminescent signal for both EFLuc and Luc2 when compared to FLuc, and a greater than 106-fold increase for RLuc8.6 when compared to hRLuc. ExtGLuc was not detectable in liver. Conclusions Our findings contrast, in some cases, with conclusions drawn in prior comparisons of these reporter genes, and demonstrate the need for a standardized method to evaluate alternative reporter genes in vivo. Our procedure can be adapted for reporter genes that utilize alternative imaging modalities (fluorescence, bioluminescence, MRI, SPECT, PET). PMID:21850545

Reviews.

ERIC Educational Resources Information Center

Radcliffe, George; And Others

1988-01-01

Reviews three software packages: 1) a package containing 68 programs covering general topics in chemistry; 2) a package dealing with acid-base titration curves and allows for variables to be changed; 3) a chemistry tutorial and drill package. (MVL)

Immobilization of Chlorosulfonyl-Calix[4]arene onto the surface of silica gel through the directly estrification

NASA Astrophysics Data System (ADS)

Taghvaei-Ganjali, Saeed; Zadmard, Reza; Saber-Tehrani, Mandana

2012-06-01

For the first time Chlorosulfonyl-Calix[4]arene has been chemically bonded to silica gel through the directly estrification without silane coupling agent to prepare Chlorosulfonyl-Calix[4]arene-bonded silica gel. Sample characterization was performed by various techniques such as elemental analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), powder X-ray diffraction (XRD), N2 adsorption-desorption, thermal gravimetric analysis (TGA), 29Si CP/MAS spectroscopy and acid-base titration. All data approve the successful incorporation of organic group via covalent bond. From the comparison between sulfur content determined by elemental analysis and the number of H+ determined by acid-base titration, it was shown that two ester units took place onto the new synthesized sample and two acidic sites exist on the surface.

NMR structural study of the prototropic equilibrium in solution of Schiff bases as model compounds.

PubMed

Ortegón-Reyna, David; Garcías-Morales, Cesar; Padilla-Martínez, Itzia; García-Báez, Efren; Aríza-Castolo, Armando; Peraza-Campos, Ana; Martínez-Martínez, Francisco

2013-12-31

An NMR titration method has been used to simultaneously measure the acid dissociation constant (pKa) and the intramolecular NHO prototropic constant ΔKNHO on a set of Schiff bases. The model compounds were synthesized from benzylamine and substituted ortho-hydroxyaldehydes, appropriately substituted with electron-donating and electron-withdrawing groups to modulate the acidity of the intramolecular NHO hydrogen bond. The structure in solution was established by 1H-, 13C- and 15N-NMR spectroscopy. The physicochemical parameters of the intramolecular NHO hydrogen bond (pKa, ΔKNHO and ΔΔG°) were obtained from 1H-NMR titration data and pH measurements. The Henderson-Hasselbalch data analysis indicated that the systems are weakly acidic, and the predominant NHO equilibrium was established using Polster-Lachmann δ-diagram analysis and Perrin model data linearization.

Acid-base properties of 2:1 clays. I. Modeling the role of electrostatics.

PubMed

Delhorme, Maxime; Labbez, Christophe; Caillet, Céline; Thomas, Fabien

2010-06-15

We present a theoretical investigation of the titratable charge of clays with various structural charge (sigma(b)): pyrophyllite (sigma(b) = 0 e x nm(-2)), montmorillonite (sigma(b) = -0.7 e x nm(-2)) and illite (sigma(b) = -1.2 e x nm(-2)). The calculations were carried out using a Monte Carlo method in the Grand Canonical ensemble and in the framework of the primitive model. The clay particle was modeled as a perfect hexagonal platelet, with an "ideal" crystal structure. The only fitting parameters used are the intrinsic equilibrium constants (pK(0)) for the protonation/deprotonation reactions of the broken-bond sites on the lateral faces of the clay particles, silanol, =SiO(-) + H(+) --> =SiOH, and aluminol, =AlO(-1/2) + H(+) --> =AlOH(+1/2). Simulations are found to give a satisfactory description of the acid-base titration of montmorillonite without any additional fitting parameter. In particular, combining the electrostatics from the crystal substitutions with ionization constants, the simulations satisfactorily catch the shift in the titration curve of montmorillonite according to the ionic strength. Change in the ionic strength modulates the screening of the electrostatic interactions which results in this shift. Accordingly, the PZNPC is found to shift toward alkaline pH upon increasing the permanent basal charge. Unlike previous mean field model results, a significant decrease in PZNPC values is predicted in response to stack formation. Finally, the mean field approach is shown to be inappropriate to study the acid-base properties of clays.

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

NASA Astrophysics Data System (ADS)

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

1999-10-01

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.

A comparison of skin endpoint titration and skin-prick testing in the diagnosis of allergic rhinitis.

PubMed

Gungor, Anil; Houser, Steven M; Aquino, Benjamin F; Akbar, Imran; Moinuddin, Rizwan; Mamikoglu, Bulent; Corey, Jacquelynne P

2004-01-01

Among the many methods of allergy diagnosis are intradermal testing (IDT) and skin-prick testing (SPT). The usefulness of IDT has been called into question by some authors, while others believe that studies demonstrating that SPT was superior might have been subject to bias. We conducted a study to compare the validity of SPT and IDT--specifically, the skin endpoint titration (SET) type of IDT--in diagnosing allergic rhinitis. We performed nasal provocation testing on 62 patients to establish an unbiased screening criterion for study entry. Acoustic rhinometric measurements of the nasal responses revealed that 34 patients tested positive and 28 negative. All patients were subsequently tested by SET and SPT. We found that SPT was more sensitive (85.3 vs 79.4%) and more specific (78.6 vs 67.9%) than SET as a screening procedure. The positive predictive value of SPT was greater than that of SET (82.9 vs 75.0%), as was the negative predictive value (81.5 vs 73.0%). None of these differences was statistically significant; because of the relatively small sample size, our study was powered to show only equivalency. The results of our study suggest that the information obtained by the SET method of IDT is comparable to that obtained by SPT in terms of sensitivity, specificity, and overall performance and that both SET and SPT correlate well with nasal provocation testing for ragweed. Therefore, the decision as to which to use can be based on other factors, such as the practitioner's training, the desire for quantitative results, the desire for rapid results, and the type of treatment (i.e., immunotherapy or pharmacotherapy) that is likely to be chosen on the basis of test results.

Individual Effect-Site Concentrations of Propofol are Similar at Loss of Consciousness and at Awakening

PubMed Central

Iwakiri, Hiroko; Nishihara, Noboru; Nagata, Osamu; Matsukawa, Takashi; Ozaki, Makoto; Sessler, Daniel I.

2005-01-01

Reported effect-site concentrations of propofol at loss of consciousness and recovery of consciousness vary widely. Thus, no single concentration based on a population average will prove optimal for individual patients. We therefore tested the hypothesis that individual propofol effect-site concentrations at loss and return of consciousness are similar. Propofol effect-site concentrations at loss and recovery of consciousness were estimated with a target-control infusion system in 20 adults. Propofol effect-site concentrations were gradually increased until the volunteers lost consciousness (no response to verbal stimuli); unconsciousness was maintained for 15 minutes, and the volunteers were then awakened. This protocol was repeated three times in each volunteer. Our major outcomes were the concentration producing unconsciousness and the relationship between the estimated effect-site concentrations at loss and recovery of consciousness. The target effect-site propofol concentration was 2.0 ± 0.9 at loss of consciousness and 1.8 ± 0.7 at return of consciousness (P < 0.001). The average difference between individual effect-site concentrations at return and loss of consciousness was only 0.17 ± 0.32 μg/mL (95% confidence interval for the difference 0.09 to 0.25 μg/mL). Our results thus suggest that individual titration to loss of consciousness is an alternative to dosing propofol on the basis of average population requirements. Implications Propofol can be titrated to the concentration that produces consciousness in individual patients. Provided that the propofol effect-site concentration does not much exceed the concentration initially required to produce unconsciousness, patients can be expected to awaken quickly upon completion of the procedure. PMID:15616062

On-Chip Titration of an Anticoagulant Argatroban and Determination of the Clotting Time within Whole Blood or Plasma Using a Plug-Based Microfluidic System

PubMed Central

Song, Helen; Li, Hung-Wing; Munson, Matthew S.; Van Ha, Thuong G.; Ismagilov, Rustem F.

2006-01-01

This paper describes extending plug-based microfluidics to handling complex biological fluids such as blood, solving the problem of injecting additional reagents into plugs, and applying this system to measuring of clotting time in small volumes of whole blood and plasma. Plugs are droplets transported through microchannels by fluorocarbon fluids. A plug-based microfluidic system was developed to titrate an anticoagulant (argatroban) into blood samples and to measure the clotting time using the activated partial thromboplastin time (APTT) test. To carry out these experiments, the following techniques were developed for a plug-based system: (i) using Teflon AF coating on the microchannel wall to enable formation of plugs containing blood and transport of the solid fibrin clots within plugs, (ii) using a hydrophilic glass capillary to enable reliable merging of a reagent from an aqueous stream into plugs, (iii) using bright-field microscopy to detect the formation of a fibrin clot within plugs and using fluorescent microscopy to detect the production of thrombin using a fluorogenic substrate, and (iv) titration of argatroban (0–1.5 μg/mL) into plugs and measurement of the resulting APTTs at room temperature (23 °C) and physiological temperature (37 °C). APTT measurements were conducted with normal pooled plasma (platelet-poor plasma) and with donor’s blood samples (both whole blood and platelet-rich plasma). APTT values and APTT ratios measured by the plug-based microfluidic device were compared to the results from a clinical laboratory at 37 °C. APTT obtained from the on-chip assay were about double those from the clinical laboratory but the APTT ratios from these two methods agreed well with each other. PMID:16841902

Risk factors associated with treatment discontinuation and down-titration in type 2 diabetes patients treated with sulfonylureas.

PubMed

Iglay, Kristy; Qiu, Ying; Steve Fan, Chun-Po; Li, Zhiyi; Tang, Jackson; Laires, Pedro

2016-09-01

Sulfonylurea therapy among patients with type 2 diabetes mellitus (T2DM) can be disrupted due to adverse events, including hypoglycemia. A retrospective study using the MarketScan claims database quantified the frequency of sulfonylurea discontinuation or down-titration and identified associated risk factors. Adult patients with an index sulfonylurea prescription between 2008 and 2012 and 1 year continuous enrollment pre- and post-index were included. Therapy changes assessed over 1 year post-index included discontinuation and down-titration. Discontinuation occurred if the date of a fill was >90 days from the end date of the preceding fill. Down-titration occurred when a fill had a lower equivalent dose than the fill on the index date. Kaplan-Meier methods estimated the probability of either discontinuation or down-titration over 12 months, and Cox regression models identified associated risk factors. A total of 104,082 sulfonylurea users were included in the study and the probability of either discontinuation or down-titration at 3, 6 and 12 months was 23.2%, 38.9%, and 52.3%, respectively. Major risk factors associated with therapy changes included post-index hypoglycemia (discontinuation hazard ratio [HR] = 1.78 [1.68, 1.89]; down-titration HR =2.79 [2.40, 3.23]) and concomitant use of insulin (discontinuation HR =1.48 [1.40, 1.57]; down-titration HR =1.82 [1.56, 2.11]). Other risk factors included younger age, female gender, use of second generation sulfonylureas, prior cardiovascular comorbidity and liver disease. The study was not able to assess unreported, potentially mild cases of hypoglycemia, nor was it able to evaluate the association between changes in therapy and HbA1c levels or body weight. More than half of T2DM patients who initiated sulfonylurea therapy discontinued or down-titrated within 1 year. Insulin use and hypoglycemia were associated with sulfonylurea therapy change.

Lacosamide and sodium channel-blocking antiepileptic drug cross-titration against levetiracetam background therapy.

PubMed

Baulac, M; Byrnes, W; Williams, P; Borghs, S; Webster, E; De Backer, M; Dedeken, P

2017-04-01

To assess prospectively the effectiveness of lacosamide (LCM) added to levetiracetam (LEV) after down-titration of a concomitant sodium channel blocker (SCB) among patients with focal epilepsy not adequately controlled on LEV and SCB. In this open-label trial, LCM was initiated at 100 mg/day and up-titrated to 200-600 mg/day over 9 weeks; SCB down-titration started when LCM dose reached 200 mg/day. Patients remained on stable LCM/LEV doses for 12 weeks' maintenance (21-week treatment period). The primary outcome was retention rate on LCM. Due to recruitment challenges, fewer than the planned 300 patients participated in the trial, resulting in the trial being underpowered. Overall, 120 patients (mean age 39.7 years) started and 93 completed the trial. The most frequently used SCBs were lamotrigine (39.2%), carbamazepine (30.8%) and oxcarbazepine (27.5%). Eighty-four patients adhered to protocol and discontinued their SCB after cross-titration, but there was insufficient evidence for 36 patients. Retention rate was 73.3% (88/120) for all patients and 83.3% (70/84) for those with evidence of SCB discontinuation. Seizure freedom for patients completing maintenance was 14.0% (13/93). Discontinuation due to adverse events (6.7%) and lack of efficacy (3.3%) occurred primarily during cross-titration. Most frequently reported adverse events during treatment were dizziness (23.3%), headache (15.0%) and fatigue (8.3%). In patients with uncontrolled seizures on LEV/SCB, the LCM/LEV combination appeared to be effective and well tolerated. A cross-titration schedule-flexible LCM up-titration, concomitant SCB down-titration and stable background LEV-could present a feasible and practical approach to initiating LCM while minimizing pharmacodynamic interactions with a SCB. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Biological Evaluation of Methods for the Determination of Free Available Chlorine.

DTIC Science & Technology

1980-03-01

tri • :., t at pH 6.0, 20’C. Lowest C1 level for false positive, mg/l Chloramine Species Test NH2CI NHC1 2 NCI1 DPDT 4.8 b 0.8 DPDTSF 4.8 b 0.6 DPDP 1.1...Available Chlorine Chlorine Membrane Electrode T )PD FACTS biofac Amperometric titration 20. ASIST’IACT C’ntAtmoe so &eJie .b f nerandm Idenwlry by block...methods tested yielded false positive determinations of free chlorine with one or more of the inorganic chloramines . The FACTS procedure was the most

Radiocarbon tracer measurements of atmospheric hydroxyl radical concentrations

NASA Technical Reports Server (NTRS)

Campbell, M. J.; Farmer, J. C.; Fitzner, C. A.; Henry, M. N.; Sheppard, J. C.

1986-01-01

The usefulness of the C-14 tracer in measurements of atmospheric hydroxyl radical concentration is discussed. The apparatus and the experimental conditions of three variations of a radiochemical method of atmosphere analysis are described and analyzed: the Teflon bag static reactor, the flow reactor (used in the Wallops Island tests), and the aircraft OH titration reactor. The procedure for reduction of the aircraft reactor instrument data is outlined. The problems connected with the measurement of hydroxyl radicals are discussed. It is suggested that the gas-phase radioisotope methods have considerable potential in measuring tropospheric impurities present in very low concentrations.

Pulsating potentiometric titration technique for assay of dissolved oxygen in water at trace level.

PubMed

Sahoo, P; Ananthanarayanan, R; Malathi, N; Rajiniganth, M P; Murali, N; Swaminathan, P

2010-06-11

A simple but high performance potentiometric titration technique using pulsating sensors has been developed for assay of dissolved oxygen (DO) in water samples down to 10.0 microg L(-1) levels. The technique involves Winkler titration chemistry, commonly used for determination of dissolved oxygen in water at mg L(-1) levels, with modification in methodology for accurate detection of end point even at 10.0 microg L(-1) levels DO present in the sample. An indigenously built sampling cum pretreatment vessel has been deployed for collection and chemical fixing of dissolved oxygen in water samples from flowing water line without exposure to air. A potentiometric titration facility using pulsating sensors developed in-house is used to carry out titration. The power of the titration technique has been realised in estimation of very dilute solution of iodine equivalent to 10 microg L(-1) O(2). Finally, several water samples containing dissolved oxygen from mg L(-1) to microg L(-1) levels were successfully analysed with excellent reproducibility using this new technique. The precision in measurement of DO in water at 10 microg L(-1) O(2) level is 0.14 (n=5), RSD: 1.4%. Probably for the first time a potentiometric titration technique has been successfully deployed for assay of dissolved oxygen in water samples at 10 microg L(-1) levels. Copyright 2010 Elsevier B.V. All rights reserved.

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

PubMed

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

2015-01-01

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

Production of ⁶¹Cu by the natZn(p,α) reaction: Improved separation and specific activity determination by titration with three chelators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asad, Ali H.; Smith, Suzanne V.; Morandeau, Laurence M.

In this study, the cyclotron-based production of position-emitting ⁶¹Cu using the (p,α) reaction at 11.7 MeV was investigated starting from natural-zinc ( natZn) and enriched ⁶⁴Zn-foil targets, as well as its subsequent purification. For natZn, a combination of three resins were assessed to separate ⁶¹Cu from contaminating 66,67,68Ga and natZn. The specific activity of the purified ⁶¹Cu determined using ICP-MS analysis ranged from 143.3±14.3(SD) to 506.2±50.6 MBq/μg while the titration method using p-SCN-Bn-DOTA, p-SCN-Bn-NOTA and diamsar gave variable results (4.7±0.2 to 412.5±15.3 MBq/μg), with diamsar lying closest to the ICP-MS values. Results suggest that the p-SCN-Bn-DOTA and p-SCN-Bn-NOTA titration methodsmore » are significantly affected by the presence of trace-metal contaminants.« less

Production of ⁶¹Cu by the natZn(p,α) reaction: Improved separation and specific activity determination by titration with three chelators

DOE PAGES

Asad, Ali H.; Smith, Suzanne V.; Morandeau, Laurence M.; ...

2015-09-01

In this study, the cyclotron-based production of position-emitting ⁶¹Cu using the (p,α) reaction at 11.7 MeV was investigated starting from natural-zinc ( natZn) and enriched ⁶⁴Zn-foil targets, as well as its subsequent purification. For natZn, a combination of three resins were assessed to separate ⁶¹Cu from contaminating 66,67,68Ga and natZn. The specific activity of the purified ⁶¹Cu determined using ICP-MS analysis ranged from 143.3±14.3(SD) to 506.2±50.6 MBq/μg while the titration method using p-SCN-Bn-DOTA, p-SCN-Bn-NOTA and diamsar gave variable results (4.7±0.2 to 412.5±15.3 MBq/μg), with diamsar lying closest to the ICP-MS values. Results suggest that the p-SCN-Bn-DOTA and p-SCN-Bn-NOTA titration methodsmore » are significantly affected by the presence of trace-metal contaminants.« less

Nurses' reported thinking during medication administration.

PubMed

Eisenhauer, Laurel A; Hurley, Ann C; Dolan, Nancy

2007-01-01

To document nurses' reported thinking processes during medication administration before and after implementation of point-of-care technology. Semistructured interviews and real-time tape recordings were used to document the thinking processes of 40 nurses practicing in inpatient care units in a large tertiary care teaching hospital in the northeastern US. Content analysis resulted in identification of 10 descriptive categories of nurses' thinking: communication, dose-time, checking, assessment, evaluation, teaching, side effects, work arounds, anticipating problem solving, and drug administration. Situations requiring judgment in dosage, timing, or selection of specific medications (e.g., pain management, titration of antihypertensives) provided the most explicit data about nurses' use of critical thinking and clinical judgment. A key element was nurses' constant professional vigilance to ensure that patients received their appropriate medications. Nurses' thinking processes extended beyond rules and procedures and were based on patient data and interdisciplinary professional knowledge to provide safe and effective care. Identification of thinking processes can help nurses to explain the professional expertise inherent in medication administration beyond the technical application of the "5 rights."

Development of analytical procedures for coprocessing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogh, J.W.; Anderson, R.P.

1990-05-01

Maya crude residue and Illinois No. 6 coal have been processed together over a range of reactant ratios to produce material for study of the product composition and of the coprocessing chemistry. The reaction conditions have been described in previous reports. Acid fractions have been derivatized to produce {sup 13}C tagged products suitable for NMR analysis. The acids have been identified as phenols and other oxygen acids, nitrogen acids including carbazoles, and benzylic and sulfur acids. All of the acid fractions appear to be essentially monofunctional. Base fractions were analyzed by nonaqueous titration and were shown to consist of azaarenesmore » and arylamines. Two of the distillates boiling below 175{degrees}C were analyzed by PIANO capillary gas chromatography. Maya crude petroleum fractions similar to those obtained from coprocessing products have been analyzed for carbon isotope ratios. These fractions were prepared directly from the Maya crude without application of hydrogenation or other processing chemistry. Trends indicating isotopic fractionation coprocessing to that reported earlier for coprocessing products were observed. 14 figs., 13 tabs.« less

Physical, chemical and kinetic factors affecting prion infectivity

PubMed Central

Properzi, Francesca; Badhan, Anjna; Klier, Steffi; Schmidt, Christian; Klöhn, Peter C.; Wadsworth, Jonathan D. F.; Clarke, Anthony R.; Jackson, Graham S.; Collinge, John

2016-01-01

ABSTRACT The mouse-adapted scrapie prion strain RML is one of the most widely used in prion research. The introduction of a cell culture-based assay of RML prions, the scrapie cell assay (SCA) allows more rapid and precise prion titration. A semi-automated version of this assay (ASCA) was applied to explore a range of conditions that might influence the infectivity and properties of RML prions. These include resistance to freeze-thaw procedures; stability to endogenous proteases in brain homogenate despite prolonged exposure to varying temperatures; distribution of infective material between pellet and supernatant after centrifugation, the effect of reducing agents and the influence of detergent additives on the efficiency of infection. Apparent infectivity is increased significantly by interaction with cationic detergents. Importantly, we have also elucidated the relationship between the duration of exposure of cells to RML prions and the transmission of infection. We established that the infection process following contact of cells with RML prions is rapid and followed an exponential time course, implying a single rate-limiting process. PMID:27282252

Physical, chemical and kinetic factors affecting prion infectivity.

PubMed

Properzi, Francesca; Badhan, Anjna; Klier, Steffi; Schmidt, Christian; Klöhn, Peter C; Wadsworth, Jonathan D F; Clarke, Anthony R; Jackson, Graham S; Collinge, John

2016-05-03

The mouse-adapted scrapie prion strain RML is one of the most widely used in prion research. The introduction of a cell culture-based assay of RML prions, the scrapie cell assay (SCA) allows more rapid and precise prion titration. A semi-automated version of this assay (ASCA) was applied to explore a range of conditions that might influence the infectivity and properties of RML prions. These include resistance to freeze-thaw procedures; stability to endogenous proteases in brain homogenate despite prolonged exposure to varying temperatures; distribution of infective material between pellet and supernatant after centrifugation, the effect of reducing agents and the influence of detergent additives on the efficiency of infection. Apparent infectivity is increased significantly by interaction with cationic detergents. Importantly, we have also elucidated the relationship between the duration of exposure of cells to RML prions and the transmission of infection. We established that the infection process following contact of cells with RML prions is rapid and followed an exponential time course, implying a single rate-limiting process.

Chemical and sensory quality of fresh pomegranate fruits exposed to gamma radiation as quarantine treatment.

PubMed

Shahbaz, Hafiz Muhammad; Ahn, Jae-Jun; Akram, Kashif; Kim, Hyo-Young; Park, Eun-Joo; Kwon, Joong-Ho

2014-02-15

The U.S. Department of Agriculture in February 2012 approved the import of fresh pomegranates subjected to irradiation as a quarantine procedure with a minimum absorbed dose of 0.4kGy against different pests. This study evaluated the application of different gamma-irradiation doses (0.4, 1, and 2kGy) in fresh pomegranate fruits and their effect on the chemical and sensory characteristics. The total soluble solids, titratable acidity, and pH values remained unaffected up to 1kGy treatment. Irradiation caused a significant decrease in the total anthocyanins and phenolic content. A strong positive correlation was observed among the antioxidant activities, total phenolics and anthocyanin contents. In general, a stronger preference was shown by sensory panelists for the juice from irradiated fruits. This study provides research-based information about the application of irradiation as a quarantine disinfestation treatment to enhance the marketing and consumer acceptance of pomegranates. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quantitative Analysis of Sulfate in Water by Indirect EDTA Titration

ERIC Educational Resources Information Center

Belle-Oudry, Deirdre

2008-01-01

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

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

Smith, Robert L.; Popham, Ronald E.

1983-01-01

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)

Microscale pH Titrations Using an Automatic Pipet.

ERIC Educational Resources Information Center

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

2002-01-01

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

Does a patient-managed insulin intensification strategy with insulin glargine and insulin glulisine provide similar glycemic control as a physician-managed strategy? Results of the START (Self-Titration With Apidra to Reach Target) Study: a randomized noninferiority trial.

PubMed

Harris, Stewart B; Yale, Jean-François; Berard, Lori; Stewart, John; Abbaszadeh, Babak; Webster-Bogaert, Susan; Gerstein, Hertzel C

2014-01-01

OBJECTIVE Diabetes self-management is universally regarded as a foundation of diabetes care. We determined whether comparable glycemic control could be achieved by self-titration versus physician titration of a once-daily bolus insulin dose in patients with type 2 diabetes who are unable to achieve optimal glycemia control with a basal insulin. RESEARCH DESIGN AND METHODS Patients with type 2 diabetes, an HbA1c level >7% (53 mmol/mol), and either nocturnal hypoglycemia episodes or an insufficient basal insulin glargine level (with or without oral agents) to achieve a fasting plasma glucose level ≤6 mmol/L (108 mg/dL) were studied. Participants all had bolus insulin glulisine added at breakfast and were allocated to either algorithm-guided patient self-titration or physician titration. The primary outcome was an HbA1c level ≤7% (53 mmol/mol) without severe hypoglycemia. RESULTS After a mean (SD) follow-up of 159.4 days (36.2 days), 28.4% of participants in the self-titration arm vs. 21.2% in the physician titration arm achieved an HbA1c level of ≤7% (53 mmol/mol) without severe hypoglycemia (between-group absolute difference 7.2%; 95% CI -3.2 to 17.7). The lower end of this 95% confidence interval was within the predetermined noninferiority boundary of -5% (P noninferiority = 0.011). CONCLUSIONS In stable patients with type 2 diabetes who are receiving doses of basal insulin glargine who require bolus insulin, a simple bolus insulin patient-managed titration algorithm is as effective as a physician-managed algorithm.

Rapid clozapine titration in treatment-refractory bipolar disorder.

PubMed

Ifteni, Petru; Correll, Christoph U; Nielsen, Jimmi; Burtea, Victoria; Kane, John M; Manu, Peter

2014-09-01

Clozapine is effective in treatment-refractory bipolar disorder (BD). Guidelines recommend slow titration to prevent seizures, hypotension and myocarditis, but this stance is not supported by comparative data. To evaluate the safety and effectiveness of rapid clozapine titration in BD. Analysis of a consecutive cohort of treatment-refractory BD patients with mixed/manic episode admitted on alternate days to one of two units of a psychiatric hospital. On one unit, clozapine was started at 25mg followed by 25-50mg as needed every 6h (maximum=100mg/day) on day 1, followed by increases of 25-100mg/day. On the other unit, clozapine was initiated with 25mg in day 1, followed by increases of 25-50mg/day. The primary outcome was the number of days from starting clozapine until readiness for discharge, adjusted in logistic regression for the number of antipsychotics tried during the hospitalization, psychotropic co-treatments and presence of psychotic features. Patients subject to rapid (N=44) and standard (N=23) titration were similar in age, gender, smoking status, body mass index, illness severity at baseline and discharge, and highest clozapine dose. Clozapine was discontinued due to hypotension (N=1) and pneumonia (N=1) during rapid titration, and for excessive sedation (N=1) in each titration group. The number of hospital days from starting clozapine until readiness for discharge was 3.8 days shorter in the rapid titration group (12.7±6.3 vs. 16.5±5.8, p=0.0077). Rapid clozapine titration appeared safe and effective for treatment-refractory BD. The potential for shorter hospital stays justifies prospective trials of this method. Copyright © 2014 Elsevier B.V. All rights reserved.

Clinical, polysomnographic, and CPAP titration features of obstructive sleep apnea: Mixed versus purely obstructive type.

PubMed

Lee, Sang-Ahm; Lee, Gha-Hyun; Chung, Yoo-Sam; Kim, Woo Sung

2015-08-15

To determine whether obstructive sleep apnea syndrome (OSAS) patients with mixed sleep apnea (MSA) have different clinical, polysomnographic, and continuous positive airway pressure (CPAP) titration findings compared to OSAS patients without MSA. We retrospectively reviewed the records of OSAS patients who had undergone CPAP titration and categorized them into pure-OSA and mixed-OSA groups. Demographic features, daytime sleepiness, and apnea severity were compared between the two groups using univariate and multivariate analyses. CPAP titration findings were also compared between the two groups. One hundred and ninety-five subjects (n=126 pure-OSA; n=69 mixed-OSA) were included in the analysis. Compared to the pure-OSA group, the mixed-OSA group had a higher percentage of males (p=0.003) and a higher body mass index (p=0.044), Epworth Sleepiness Scale score (p=0.028), and apnea-hypopnea index (AHI) (p<0.001). In logistic regression analysis, older age, male sex, and higher body mass index were independently associated with mixed-OSA before PSG study. When using AHI as a covariable, the higher AHI with older age, male sex, and daytime sleepiness was independently related to mixed-OSA. The mixed-OSA group had a higher percentage of patients with complex sleep apnea, a lower percentage of patients with optimal titration, and a higher titrated pressure than the pure-OSA group. Severe OSA, older age, male sex, obesity, and daytime sleepiness were related to mixed-OSA. Complex sleep apnea, less optimal titration, and a higher titrated CPAP were also associated with MSA in OSAS patients. Copyright © 2015 Elsevier B.V. All rights reserved.

Fluorometric titration approach for calibration of quantity of binding site of purified monoclonal antibody recognizing epitope/hapten nonfluorescent at 340 nm.

PubMed

Yang, Xiaolan; Hu, Xiaolei; Xu, Bangtian; Wang, Xin; Qin, Jialin; He, Chenxiong; Xie, Yanling; Li, Yuanli; Liu, Lin; Liao, Fei

2014-06-17

A fluorometric titration approach was proposed for the calibration of the quantity of monoclonal antibody (mcAb) via the quench of fluorescence of tryptophan residues. It applied to purified mcAbs recognizing tryptophan-deficient epitopes, haptens nonfluorescent at 340 nm under the excitation at 280 nm, or fluorescent haptens bearing excitation valleys nearby 280 nm and excitation peaks nearby 340 nm to serve as Förster-resonance-energy-transfer (FRET) acceptors of tryptophan. Titration probes were epitopes/haptens themselves or conjugates of nonfluorescent haptens or tryptophan-deficient epitopes with FRET acceptors of tryptophan. Under the excitation at 280 nm, titration curves were recorded as fluorescence specific for the FRET acceptors or for mcAbs at 340 nm. To quantify the binding site of a mcAb, a universal model considering both static and dynamic quench by either type of probes was proposed for fitting to the titration curve. This was easy for fitting to fluorescence specific for the FRET acceptors but encountered nonconvergence for fitting to fluorescence of mcAbs at 340 nm. As a solution, (a) the maximum of the absolute values of first-order derivatives of a titration curve as fluorescence at 340 nm was estimated from the best-fit model for a probe level of zero, and (b) molar quantity of the binding site of the mcAb was estimated via consecutive fitting to the same titration curve by utilizing such a maximum as an approximate of the slope for linear response of fluorescence at 340 nm to quantities of the mcAb. This fluorometric titration approach was proved effective with one mcAb for six-histidine and another for penicillin G.

Titration ELISA as a Method to Determine the Dissociation Constant of Receptor Ligand Interaction.

PubMed

Eble, Johannes A

2018-02-15

The dissociation constant describes the interaction between two partners in the binding equilibrium and is a measure of their affinity. It is a crucial parameter to compare different ligands, e.g., competitive inhibitors, protein isoforms and mutants, for their binding strength to a binding partner. Dissociation constants are determined by plotting concentrations of bound versus free ligand as binding curves. In contrast, titration curves, in which a signal that is proportional to the concentration of bound ligand is plotted against the total concentration of added ligand, are much easier to record. The signal can be detected spectroscopically and by enzyme-linked immunosorbent assay (ELISA). This is exemplified in a protocol for a titration ELISA that measures the binding of the snake venom-derived rhodocetin to its immobilized target domain of α2β1 integrin. Titration ELISAs are versatile and widely used. Any pair of interacting proteins can be used as immobilized receptor and soluble ligand, provided that both proteins are pure, and their concentrations are known. The difficulty so far has been to determine the dissociation constant from a titration curve. In this study, a mathematical function underlying titration curves is introduced. Without any error-prone graphical estimation of a saturation yield, this algorithm allows processing of the raw data (signal intensities at different concentrations of added ligand) directly by mathematical evaluation via non-linear regression. Thus, several titration curves can be recorded simultaneously and transformed into a set of characteristic parameters, among them the dissociation constant and the concentration of binding-active receptor, and they can be evaluated statistically. When combined with this algorithm, titration ELISAs gain the advantage of directly presenting the dissociation constant. Therefore, they may be used more efficiently in the future.

On the connection between autoimmunity, tic disorders and obsessive-compulsive disorders: a meta-analysis on anti-streptolysin O titres.

PubMed

Pozzi, Marco; Pellegrino, Paolo; Carnovale, Carla; Perrone, Valentina; Antoniazzi, Stefania; Perrotta, Cristiana; Radice, Sonia; Clementi, Emilio

2014-12-01

Anti-streptolysin O (ASO) titration is useful in the context of autoimmune pathologies, including specific cases of tic and obsessive-compulsive disorders occurring after streptococcal infections. There is currently a lack of consensus on the use of ASO titres; therefore we performed a meta-analysis to systematise available data and clarify the role of ASO titres in the context of neuropsychiatric disorders. A meta-analysis was performed on ASO titration in neuropsychiatric patients, including tic disorders and obsessive-compulsive disorders. Included studies reported numbers of positive subjects, depending on a chosen threshold, or detailed ASO titrations. Three hundred and twenty nine studies were identified, of which 13 were eligible for meta-analysis. Due to limited available data, only tic disorders were evaluated. The odds ratio of finding an abnormal ASO titre in patients was 3.22 (95% C.I. 1.51-6.88) as compared to healthy controls and 16.14 (95% C.I. 8.11-32.11) as compared to non-psychiatric patients. Studies using different thresholds were generally concordant. ASO titres were also compared quantitatively, finding an overall difference of the means of 70.50 U/ml (95% C.I. 25.21-115.80) in favour of patients with tic disorders. Based on current evidence, tic disorders are associated with a significant increase in ASO titres, evident both in a threshold-level perspective and on a quantitative level. These results encourage the systematisation of ASO titration in the context of tic disorders.

The effect of packaging methods (paper, active paper, and edible coating) on the characteristic of papaya MJ9 in ambient temperature storage

NASA Astrophysics Data System (ADS)

Suwanti, D.; Utami, R.; Kawiji; Praseptiangga, D.; Khasanah, L. U.

2018-01-01

Papaya is one of the export commodities that contain high vitamin C but having short shelf-life. One method that use to extend the shelf-life and maintain the quality of papaya is packaging. The aim of this study was to investigate the effect of the packaging methods (paper, active paper and edible coating) on the characteristics of papaya MJ9 (weight loss, firmness, total soluble solid (TSS), Total Titratable Acid (TTA), pH, vitamin C and total mold and yeast). The packaging methods were control (F1), wrapping paper (F2), wrapping active paper (F3), combination of edible coating and wrapping paper (F4), and combination of edible coating and wrapping active paper (F5). The result showed that paper packaging, edible coating and active paper packaging significantly affected the weight loss, firmness, total soluble solid, total titratable acids, pH, vitamin C, and total mold and yeast of papaya. The weight loss, total soluble solid and pH of packaged papaya was lower than that of control sample, however, the value of firmness and total titratable acid was higher than that of the control sample. Packaging can inhibit the increase of weight loss, total soluble solids and pH, and the decrease of firmness, total titratable acid, vitamin C and total mold and yeast. Based on the papaya characteristics, the selected packaging method was the combination of edible coating and wrapping active paper.

Delay Discounting in Lewis and Fischer 344 Rats: Steady-state and Rapid-determination Adjusting-amount Procedures

PubMed Central

Stein, Jeffrey S; Pinkston, Jonathan W; Brewer, Adam T; Francisco, Monica T; Madden, Gregory J

2012-01-01

Lewis rats have been shown to make more impulsive choices than Fischer 344 rats in discrete-trial choice procedures that arrange fixed (i.e., nontitrating) reinforcement parameters. However, nontitrating procedures yield only gross estimates of preference, as choice measures in animal subjects are rarely graded at the level of the individual subject. The present study was designed to examine potential strain differences in delay discounting using an adjusting-amount procedure, in which distributed (rather than exclusive) choice is observed due to dynamic titration of reinforcer magnitude across trials. Using a steady-state version of the adjusting-amount procedure in which delay was manipulated between experimental conditions, steeper delay discounting was observed in Lewis rats compared to Fischer 344 rats; further, delay discounting in both strains was well described by the traditional hyperbolic discounting model. However, upon partial completion of the present study, a study published elsewhere (Wilhelm & Mitchell, 2009) demonstrated no difference in delay discounting between these strains with the use of a more rapid version of the adjusting-amount procedure (i.e., in which delay is manipulated daily). Thus, following completion of the steady-state assessment in the present study, all surviving Lewis and Fischer 344 rats completed an approximation of this rapid-determination procedure in which no strain difference in delay discounting was observed. PMID:22693360

Delay discounting in Lewis and Fischer 344 rats: steady-state and rapid-determination adjusting-amount procedures.

PubMed

Stein, Jeffrey S; Pinkston, Jonathan W; Brewer, Adam T; Francisco, Monica T; Madden, Gregory J

2012-05-01

Lewis rats have been shown to make more impulsive choices than Fischer 344 rats in discrete-trial choice procedures that arrange fixed (i.e., nontitrating) reinforcement parameters. However, nontitrating procedures yield only gross estimates of preference, as choice measures in animal subjects are rarely graded at the level of the individual subject. The present study was designed to examine potential strain differences in delay discounting using an adjusting-amount procedure, in which distributed (rather than exclusive) choice is observed due to dynamic titration of reinforcer magnitude across trials. Using a steady-state version of the adjusting-amount procedure in which delay was manipulated between experimental conditions, steeper delay discounting was observed in Lewis rats compared to Fischer 344 rats; further, delay discounting in both strains was well described by the traditional hyperbolic discounting model. However, upon partial completion of the present study, a study published elsewhere (Wilhelm & Mitchell, 2009) demonstrated no difference in delay discounting between these strains with the use of a more rapid version of the adjusting-amount procedure (i.e., in which delay is manipulated daily). Thus, following completion of the steady-state assessment in the present study, all surviving Lewis and Fischer 344 rats completed an approximation of this rapid-determination procedure in which no strain difference in delay discounting was observed.

Calcium-buffering effects of gluconate and nucleotides, as determined by a novel fluorimetric titration method.

PubMed

Woehler, Andrew; Lin, Kun-Han; Neher, Erwin

2014-11-15

Significantly more Ca(2+) influx is required for eliciting release of neurotransmitter during whole cell patch clamp recording in the Calyx of Held, when gluconate with 3 mm free ATP is used as pipette filling solution, as compared to a methanesulfonate-based solution with excess Mg(2+). This reduction in efficiency of Ca(2+) in eliciting release is due to low-affinity Ca(2+) binding of both gluconate and ATP(2-) anions. To study these effects we developed a simple fluorimeteric titration procedure, which reports the dissociation constant, KD, of a given Ca(2+) indicator dye, multiplied by 1 plus the sum of Ca(2+) binding ratios of any anions, which act as low-affinity Ca(2+) ligands. For solutions without Ca(2+) binding anions we find KD values for Fura2FF ranging from 11.5 ± 1.7 to 15.6 ± 7.47 μm depending on the dominant anion used. For Fura6F and KCl-based solutions we find KD = 17.8 ± 1.3 μm. For solutions with gluconate as the main anion and for solutions that contain nucleotides, such as ATP and GTP, we find much higher values for the product. Assuming that the KD of the indicator dye is equal to that of KCl-based solutions we calculate the summed Ca(2+) binding ratios and find a value of 3.55 for a solution containing 100 mm potassium gluconate and 4 mm ATP. Gluconate contributes a value of 1.75 to this number, while the contribution of ATP depends strongly on the presence of Mg(2+) and varies from 0.8 (with excess Mg(2+)) to 13.8 (in the presence of 3 mm free ATP). Methanesulfonate has negligible Ca(2+) binding capacity. These results explain the reduced efficiency of Ca(2+) influx in the presence of gluconate or nucleotides, as these anions are expected to intercept Ca(2+) ions at short distance. © 2014 The Authors. The Journal of Physiology © 2014 The Physiological Society.

Graphene oxide for acid catalyzed-reactions: Effect of drying process

NASA Astrophysics Data System (ADS)

Gong, H. P.; Hua, W. M.; Yue, Y. H.; Gao, Z.

2017-03-01

Graphene oxides (GOs) were prepared by Hummers method through various drying processes, and characterized by XRD, SEM, FTIR, XPS and N2 adsorption. Their acidities were measured using potentiometric titration and acid-base titration. The catalytic properties were investigated in the alkylation of anisole with benzyl alcohol and transesterification of triacetin with methanol. GOs are active catalysts for both reaction, whose activity is greatly affected by their drying processes. Vacuum drying GO exhibits the best performance in transesterification while freezing drying GO is most active for alkylation. The excellent catalytic behavior comes from abundant surface acid sites as well as proper surface functional groups, which can be obtained by selecting appropriate drying process.

Comparative studies on the salt content of white bread and wholemeal bread

NASA Astrophysics Data System (ADS)

Adi Riyanto, Rachmad; Eko Caraka, Rezzy

2018-05-01

Bread contributes to the high salt daily intake of human which can cause increased blood pressure and cardiovascular health problems. Salt in bread has some important functions that affect the bread quality. However, some government organization regulated to reduce salt in bread production. Hence, this study aims to explain the salt content in commercial white bread and wholemeal bread by Mohr titration and Atomic Absorption Spectroscopy (AAS). Based on statistical analysis by using F test and t-test can be concluded there is no significant difference of salt content in both types of bread (p>0.05), however the result by Mohr titration was significantly higher than by AAS (p<0.05).

Assessing the acid-base and conformational properties of histidine residues in human prion protein (125-228) by means of pK(a) calculations and molecular dynamics simulations.

PubMed

Langella, Emma; Improta, Roberto; Crescenzi, Orlando; Barone, Vincenzo

2006-07-01

A thorough study of the acid-base behavior of the four histidines and the other titratable residues of the structured domain of human prion protein (125-228) is presented. By using multi-tautomer electrostatic calculations, average titration curves have been built for all titratable residues, using the whole bundles of NMR structures determined at pH 4.5 and 7.0. According to our results, (1) only histidine residues are likely to be involved in the first steps of the pH-driven conformational transition of prion protein; (2) the pK(a)'s of His140 and His177 are approximately 7.0, whereas those of His155 and His187 are < 5.5. 10-ns long molecular dynamics simulations have been performed on five different models, corresponding to the most significant combinations of histidine protonation states. A critical comparison between the available NMR structures and our computational results (1) confirms that His155 and His187 are the residues whose protonation is involved in the conformational rearrangement of huPrP in mildly acidic condition, and (2) shows how their protonation leads to the destructuration of the C-terminal part of HB and to the loss of the last turn of HA that represent the crucial microscopic steps of the rearrangement. (c) 2006 Wiley-Liss, Inc.

The kinetic study of the inhibition of human cholinesterases by demeton-S-methyl shows that cholinesterase-based titration methods are not suitable for this organophosphate.

PubMed

Bazire, Alexandre; Gillon, Emilie; Lockridge, Oksana; Vallet, Virginie; Nachon, Florian

2011-04-01

The organophosphorus insecticide, demeton-S-methyl (DSM), is considered as a good surrogate of the highly toxic nerve agent VX for skin absorption studies due to similar physico-chemical properties and in vitro percutaneous penetration profile. But, when skin distribution was estimated by measuring inhibition of cholinesterase activity, the results were poorly reproducible. The various grades of commercial DSM solutions were suspected to be the origin of the discrepancies. This hypothesis was tested by measuring inhibition of human acetyl- and butyrylcholinesterase by two commercial DSM solutions. The inhibition rate was independent on the enzyme concentration confirming pseudo-first order conditions. But complete inhibition of butyrylcholinesterase activity was achieved only when the DSM concentration was at least 1500-fold higher than the enzyme concentration. Besides, complete inhibition of acetylcholinesterase was never achieved. Mass spectrometry analysis of the inhibited butyrylcholinesterase adducts identified monomethoxyphosphorylated-serine, the aged product of inhibition by DSM or a derivative with a modified leaving group. Neither spontaneous reactivation nor aging of the dimethoxyphosphorylated-serine could account for the inhibition kinetics observed, suggesting an overly complicated kinetic scheme not compatible with the requirement of a titration experiment. In conclusion, cholinesterase-based analytical methods should be avoided for DSM titration in skin penetration studies. Copyright © 2011 Elsevier Ltd. All rights reserved.

A highly selective and sensitive fluorescent chemosensor and its application for rapid on-site detection of Al3 +

NASA Astrophysics Data System (ADS)

Yue, Xiao-li; Wang, Zhao-qing; Li, Chao-rui; Yang, Zheng-yin

2018-03-01

In this paper, a simple naphthalene-based derivative (HL) has been designed and synthesized as a Al3 +-selective fluorescent chemosensor based on the PET mechanism. HL exhibited high selectivity and sensitivity towards Al3 + over other commonly coexisting metal ions in ethanol with a detection limit of 2.72 nM. The 1:1 binding stoichiometry of the complex (HL-Al3 +) was determined from the Job's plot based on fluorescence titrations and the ESI-MS spectrum data. Moreover, the binding site of HL with Al3 + was assured by the 1H NMR titration experiment. The binding constant (Ka) of the complex (HL-Al3 +) was calculated to be 5.06 × 104 M- 1 according to the Benesi-Hildebrand equation. In addition, the recognizing process of HL towards Al3 + was chemically reversible by adding Na2EDTA. Importantly, HL could directly and rapidly detect aluminum ion through the filter paper without resorting to additional instrumental analysis.

Total Acid Value Titration of Hydrotreated Biomass Fast Pyrolysis Oil: Determination of Carboxylic Acids and Phenolics with Multiple End-Point Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christensen, E.; Alleman, T. L.; McCormick, R. L.

Total acid value titration has long been used to estimate corrosive potential of petroleum crude oil and fuel oil products. The method commonly used for this measurement, ASTM D664, utilizes KOH in isopropanol as the titrant with potentiometric end point determination by pH sensing electrode and Ag/AgCl reference electrode with LiCl electrolyte. A natural application of the D664 method is titration of pyrolysis-derived bio-oil, which is a candidate for refinery upgrading to produce drop in fuels. Determining the total acid value of pyrolysis derived bio-oil has proven challenging and not necessarily amenable to the methodology employed for petroleum products duemore » to the different nature of acids present. We presented an acid value titration for bio-oil products in our previous publication which also utilizes potentiometry using tetrabutylammonium hydroxide in place of KOH as the titrant and tetraethylammonium bromide in place of LiCl as the reference electrolyte to improve the detection of these types of acids. This method was shown to detect numerous end points in samples of bio-oil that were not detected by D664. These end points were attributed to carboxylic acids and phenolics based on the results of HPLC and GC-MS studies. Additional work has led to refinement of the method and it has been established that both carboxylic acids and phenolics can be determined accurately. Use of pH buffer calibration to determine half-neutralization potentials of acids in conjunction with the analysis of model compounds has allowed us to conclude that this titration method is suitable for the determination of total acid value of pyrolysis oil and can be used to differentiate and quantify weak acid species. The measurement of phenolics in bio-oil is subject to a relatively high limit of detection, which may limit the utility of titrimetric methodology for characterizing the acidic potential of pyrolysis oil and products.« less

Computer Series, 13.

ERIC Educational Resources Information Center

Moore, John W., Ed.

1981-01-01

Provides short descriptions of chemists' applications of computers in instruction: an interactive instructional program for Instrumental-Qualitative Organic Analysis; question-and-answer exercises in organic chemistry; computerized organic nomenclature drills; integration of theoretical and descriptive materials; acid-base titration simulation;…

Electronic Detection of Lectins Using Carbohydrate Functionalized Nanostructures: Graphene versus Carbon Nanotubes

PubMed Central

Chen, Yanan; Vedala, Harindra; Kotchey, Gregg P.; Audfray, Aymeric; Cecioni, Samy; Imberty, Anne; Vidal, Sébastien; Star, Alexander

2012-01-01

Here we investigated the interactions between lectins and carbohydrates using field-effect transistor (FET) devices comprised of chemically converted graphene (CCG) and single-walled carbon nanotubes (SWNTs). Pyrene- and porphyrin-based glycoconjugates were functionalized noncovalently on the surface of CCG-FET and SWNT-FET devices, which were then treated with 2 µM of nonspecific and specific lectins. In particular, three different lectins (PA-IL, PA-IIL and ConA) and three carbohydrate epitopes (galactose, fucose and mannose) were tested. The responses of 36 different devices were compared and rationalized using computer-aided models of carbon nanostructure/glycoconjugate interactions. Glycoconjugates surface coverage in addition to one-dimensional structures of SWNTs resulted in optimal lectin detection. Additionally, lectin titration data of SWNT- and CCG-based biosensors were used to calculate lectin dissociation constants (Kd) and compare them to the values obtained from the isothermal titration microcalorimetry (ITC) technique. PMID:22136380

A rapid and efficient branched DNA hybridization assay to titer lentiviral vectors.

PubMed

Nair, Ayyappan; Xie, Jinger; Joshi, Sarasijam; Harden, Paul; Davies, Joan; Hermiston, Terry

2008-11-01

A robust assay to titer lentiviral vectors is imperative to qualifying their use in drug discovery, target validation and clinical applications. In this study, a novel branched DNA based hybridization assay was developed to titer lentiviral vectors by quantifying viral RNA genome copy numbers from viral lysates without having to purify viral RNA, and this approach was compared with other non-functional (p24 protein ELISA and viral RT-qPCR) and a functional method (reporter gene expression) used commonly. The RT-qPCR method requires purification of viral RNA and the accuracy of titration therefore depends on the efficiency of purification; this requirement is ameliorated in the hybridization assay as RNA is measured directly in viral lysates. The present study indicates that the hybridization based titration assay performed on viral lysates was more accurate and has additional advantages of being rapid, robust and not dependent on transduction efficiency in different cell types.

Determination of the intrinsic redox potentials of FeS centers of respiratory complex I from experimental titration curves

PubMed Central

Medvedev, Emile S.; Couch, Vernon A.

2014-01-01

Recently, Euro et al. [Biochem. 47, 3185 (2008)] have reported titration data for seven of nine FeS redox centers of complex I from E. coli. There is a significant uncertainty in the assignment of the titration data. Four of the titration curves were assigned to N1a, N1b, N6b, and N2 centers; one curve either to N3 or N7; one more either to N4 or N5; and the last one denoted Nx could not be assigned at all. In addition, the assignment of the titration data to N6b/N6a pair is also uncertain. In this paper, using our calculated interaction energies [Couch et al. BBA 1787, 1266 (2009)], we perform statistical analysis of these data, considering a variety of possible assignments, find the best fit, and determine the intrinsic redox potentials of the centers. The intrinsic potentials could be determined with uncertainty of less than ±10 mV at 95% confidence level for best fit assignments. We also find that the best agreement between theoretical and experimental titration curves is obtained with the N6b-N2 interaction equal to 71±14 or 96±26 mV depending on the N6b/N6a titration data assignment, which is stronger than was expected and may indicate a close distance of N2 center to the membrane surface. PMID:20513348

Treatment discontinuation and tolerability as a function of dose and titration of duloxetine in the treatment of major depressive disorder.

PubMed

Harada, Eiji; Shirakawa, Osamu; Satoi, Yoichi; Marangell, Lauren B; Escobar, Rodrigo

2016-01-01

We sought to better understand how dose and titration with duloxetine treatment may impact tolerability and treatment discontinuation in patients with major depressive disorder. We investigated Phase III duloxetine trials. Group 1 was a single placebo-controlled study with a 20 mg initial dose and a slow titration to 40 and 60 mg. Group 2 was a single study with a 40 mg initial dose and final "active" doses of 40 and 60 mg (5 mg control group), with 1-week titration. Group 3 consisted of eight placebo-controlled studies with starting doses of 40, 60, and 80 mg/day with minimal titration (final dose 40-120 mg/day). Tolerability was measured by rate of discontinuation due to adverse events (DCAE). The DCAE in Group 1 were 3.6% in the 60 mg group, 3.3% in the 40 mg group, and 3.2% in the placebo group. In Group 2, the DCAE were 15.0% in the 60 mg group, 8.1% in the 40 mg group, and 4.9% in the 5 mg group. In Group 3, the DCAE were 9.7% and 4.2% in the duloxetine and placebo groups, respectively. This study suggests that starting dose and titration may have impacted tolerability and treatment discontinuation. A lower starting dose of duloxetine and slower titration may contribute to improving treatment tolerability for patients with major depressive disorder.

Dose titration of repaglinide in patients with inadequately controlled type 2 diabetes.

PubMed

Kølendorf, Klaus; Eriksson, Johan; Birkeland, Kåre I; Kjellström, Thomas; Hreidarsson, Astradur B

2004-04-01

A total of 385 drug-therapy naïve patients, with inadequately controlled type 2 diabetes, were randomised into a multinational, parallel-group study to compare two strategies for dose titration of the oral hypoglycaemic agent repaglinide. Patients were allocated to either a fasting blood glucose (FBG) monitoring group with titration target 4.4-6.1 mmol/l or to a post-prandial blood glucose (PPBG) monitoring group with titration target 4.4-8.0 mmol/l. An initial titration period of up to 8 weeks was followed by a 12-week treatment period. Glycaemic control and hypoglycaemic outcomes were compared for the respective groups. HbA(1c) decreased significantly more in the FBG monitoring group by a mean of 1.38% compared to the PPBG group by a mean of 1.22% (P=0.03). The glycaemic control targets were met by fewer patients in the FBG group than in the PPBG group (57% versus 86% (P<0.001)) despite a higher mean dose of repaglinide in the FBG group. The within-patient blood glucose variability was significantly lower in the FBG group than in the PPBG group (P<0.001). In conclusion, repaglinide lowered the HbA(1c) effectively and safely in both groups and self-monitored FBG is a suitable parameter for titration of repaglinide. Whether a lower PPBG target might be as good a guide as FBG for titration of repaglinide should be addressed in a future study.

Prescribing and up-titration in recently hospitalized heart failure patients attending a disease management program.

PubMed

Carroll, Robert; Mudge, Alison; Suna, Jessica; Denaro, Charles; Atherton, John

2016-08-01

Heart failure (HF) medications improve clinical outcomes, with optimal doses defined in clinical trials. Patient, provider and system barriers may limit achievement of optimal doses in real life settings, although disease management programs (HF-DMPs) can facilitate up-titration. Secondary analysis of a prospective cohort of 216 participants recently hospitalized with systolic HF, attending 5 HF-DMPs in Queensland, Australia. Medication history at baseline (6weeks after discharge) and 6months provided data to describe prescription rates, dosage and optimal titration of HF medications, and associations with patient and system factors were explored. At baseline, 94% were on an angiotensin converting enzyme inhibitor/angiotensin II receptor blocker (ACEI/ARB), 94% on a beta-blocker (BB) and 42% on a mineralocorticoid receptor antagonist (MRA). The proportion of participants on optimal doses of ACEI/ARB increased from 38% (baseline) to 52% (6months, p=0.001) and on optimal BB dose from 23% to 49% (p<0.001). Significant barriers to ACEI/ARB up-titration were body mass index (BMI)<25, female gender, polypharmacy, previously diagnosed HF, and tertiary hospital. Significant barriers for BB up-titration were BMI<25, previously diagnosed HF and non-cardiologist care. Effective up-titration in HF DMPs is influenced by patient, disease and service factors. Better understanding of barriers to effective up-titration in women, normal weight, and established HF patients may help provide targeted strategies for improving outcomes in these groups. Copyright © 2016 Elsevier Ltd. All rights reserved.

When instructions fail. The effects of stimulus control training on brain injury survivors' attending and reporting during hearing screenings.

PubMed

Schlund, M W

2000-10-01

Bedside hearing screenings are routinely conducted by speech and language pathologists for brain injury survivors during rehabilitation. Cognitive deficits resulting from brain injury, however, may interfere with obtaining estimates of auditory thresholds. Poor comprehension or attention deficits often compromise patient abilities to follow procedural instructions. This article describes the effects of jointly applying behavioral methods and psychophysical methods to improve two severely brain-injured survivors' attending and reporting on auditory test stimuli presentation. Treatment consisted of stimulus control training that involved differentially reinforcing responding in the presence and absence of an auditory test tone. Subsequent hearing screenings were conducted with novel auditory test tones and a common titration procedure. Results showed that prior stimulus control training improved attending and reporting such that hearing screenings were conducted and estimates of auditory thresholds were obtained.

Incorporating Guideline Adherence and Practice Implementation Issues into the Design of Decision Support for Beta-Blocker Titration for Heart Failure.

PubMed

Smith, Michael W; Brown, Charnetta; Virani, Salim S; Weir, Charlene R; Petersen, Laura A; Kelly, Natalie; Akeroyd, Julia; Garvin, Jennifer H

2018-04-01

 The recognition of and response to undertreatment of heart failure (HF) patients can be complicated. A clinical reminder can facilitate use of guideline-concordant β-blocker titration for HF patients with depressed ejection fraction. However, the design must consider the cognitive demands on the providers and the context of the work.  This study's purpose is to develop requirements for a clinical decision support tool (a clinical reminder) by analyzing the cognitive demands of the task along with the factors in the Cabana framework of physician adherence to guidelines, the health information technology (HIT) sociotechnical framework, and the Promoting Action on Research Implementation in Health Services (PARIHS) framework of health services implementation. It utilizes a tool that extracts information from medical records (including ejection fraction in free text reports) to identify qualifying patients at risk of undertreatment.  We conducted interviews with 17 primary care providers, 5 PharmDs, and 5 Registered Nurses across three Veterans Health Administration outpatient clinics. The interviews were based on cognitive task analysis (CTA) methods and enhanced through the inclusion of the Cabana, HIT sociotechnical, and PARIHS frameworks. The analysis of the interview data led to the development of requirements and a prototype design for a clinical reminder. We conducted a small pilot usability assessment of the clinical reminder using realistic clinical scenarios.  We identified organizational challenges (such as time pressures and underuse of pharmacists), knowledge issues regarding the guideline, and information needs regarding patient history and treatment status. We based the design of the clinical reminder on how to best address these challenges. The usability assessment indicated the tool could help the decision and titration processes.  Through the use of CTA methods enhanced with adherence, sociotechnical, and implementation frameworks, we designed a decision support tool that considers important challenges in the decision and execution of β-blocker titration for qualifying HF patients at risk of undertreatment. Schattauer GmbH Stuttgart.

Concurrent determination of total serum calcium and magnesium by thermometric titration with ethylenediaminetetraacetate.

PubMed

Callicott, R H; Carr, P W

1976-07-01

Total serum calcium and magnesium may be determined in one thermometric titration, with disodium ethylenediaminetetraacetate as the titrant. A 1-ml serum sample is diluted with 1 ml of tris(hydroxymethyl)aminomethane buffer (pH 8) and titrated at a constant rate with a motorized syringe buret. Results by the thermometric method compared well with those by atomic absorption spectroscopy.

Randomized clinical trial of an intravenous hydromorphone titration protocol versus usual care for management of acute pain in older emergency department patients.

PubMed

Chang, Andrew K; Bijur, Polly E; Davitt, Michelle; Gallagher, E John

2013-09-01

Opioid titration is an effective strategy for treating pain; however, titration is generally impractical in the busy emergency department (ED) setting. Our objective was to test a rapid, two-step, hydromorphone titration protocol against usual care in older patients presenting to the ED with acute severe pain. This was a prospective, randomized clinical trial of patients 65 years of age and older presenting to an adult, urban, academic ED with acute severe pain. The study was registered at http://www.clinicaltrials.gov (NCT01429285). Patients randomized to the hydromorphone titration protocol initially received 0.5 mg intravenous hydromorphone. Patients randomized to usual care received any dose of any intravenous opioid. At 15 min, patients in both groups were asked, 'Do you want more pain medication?' Patients in the hydromorphone titration group who answered 'yes' received a second dose of 0.5 mg intravenous hydromorphone. Patients in the usual care group who answered 'yes' had their ED attending physician notified, who then could administer any (or no) additional medication. The primary efficacy outcome was satisfactory analgesia defined a priori as the patient declining additional analgesia at least once when asked at 15 or 60 min after administration of the initial opioid. Dose was calculated in morphine equivalent units (MEU: 1 mg hydromorphone = 7 mg morphine). The need for naloxone to reverse adverse opioid effects was the primary safety outcome. 83.0 % of 153 patients in the hydromorphone titration group achieved satisfactory analgesia compared with 82.5 % of 166 patients in the usual care group (p = 0.91). Patients in the hydromorphone titration group received lower mean initial doses of opioids at baseline than patients in the usual care group (3.5 MEU vs. 4.7 MEU, respectively; p ≤ 0.001) and lower total opioids through 60 min (5.3 MEU vs. 6.0 MEU; p = 0.03). No patient needed naloxone. Low-dose titration of intravenous hydromorphone in increments of 0.5 mg provides comparable analgesia to usual care with less opioid over 60 min.

Subject-driven titration of biphasic insulin aspart 30 twice daily is non-inferior to investigator-driven titration in Chinese patients with type 2 diabetes inadequately controlled with premixed human insulin: A randomized, open-label, parallel-group, multicenter trial.

PubMed

Yang, Wenying; Zhu, Lvyun; Meng, Bangzhu; Liu, Yu; Wang, Wenhui; Ye, Shandong; Sun, Li; Miao, Heng; Guo, Lian; Wang, Zhanjian; Lv, Xiaofeng; Li, Quanmin; Ji, Qiuhe; Zhao, Weigang; Yang, Gangyi

2016-01-01

The present study was to compare the efficacy and safety of subject-driven and investigator-driven titration of biphasic insulin aspart 30 (BIAsp 30) twice daily (BID). In this 20-week, randomized, open-label, two-group parallel, multicenter trial, Chinese patients with type 2 diabetes inadequately controlled by premixed/self-mixed human insulin were randomized 1:1 to subject-driven or investigator-driven titration of BIAsp 30 BID, in combination with metformin and/or α-glucosidase inhibitors. Dose adjustment was decided by patients in the subject-driven group after training, and by investigators in the investigator-driven group. Eligible adults (n = 344) were randomized in the study. The estimated glycated hemoglobin (HbA1c) reduction was 14.5 mmol/mol (1.33%) in the subject-driven group and 14.3 mmol/mol (1.31%) in the investigator-driven group. Non-inferiority of subject-titration vs investigator-titration in reducing HbA1c was confirmed, with estimated treatment difference -0.26 mmol/mol (95% confidence interval -2.05, 1.53) (-0.02%, 95% confidence interval -0.19, 0.14). Fasting plasma glucose, postprandial glucose increment and self-measured plasma glucose were improved in both groups without statistically significant differences. One severe hypoglycemic event was experienced by one subject in each group. A similar rate of nocturnal hypoglycemia (events/patient-year) was reported in the subject-driven (1.10) and investigator-driven (1.32) groups. There were 64.5 and 58.1% patients achieving HbA1c <53.0 mmol/mol (7.0%), and 51.2 and 45.9% patients achieving the HbA1c target without confirmed hypoglycemia throughout the trial in the subject-driven and investigator-driven groups, respectively. Subject-titration of BIAsp 30 BID was as efficacious and well-tolerated as investigator-titration. The present study supported patients to self-titrate BIAsp 30 BID under physicians' supervision.

Sleep Quality, Short-Term and Long-Term CPAP Adherence

PubMed Central

Somiah, Manya; Taxin, Zachary; Keating, Joseph; Mooney, Anne M.; Norman, Robert G.; Rapoport, David M.; Ayappa, Indu

2012-01-01

Study Objectives: Adherence to CPAP therapy is low in patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). The purpose of the present study was to evaluate the utility of measures of sleep architecture and sleep continuity on the CPAP titration study as predictors of both short- and long-term CPAP adherence. Methods: 93 patients with OSAHS (RDI 42.8 ± 34.3/h) underwent in-laboratory diagnostic polysomnography, CPAP titration, and follow-up polysomnography (NPSG) on CPAP. Adherence to CPAP was objectively monitored. Short-term (ST) CPAP adherence was averaged over 14 days immediately following the titration study. Long-term (LT) CPAP adherence was obtained in 56/93 patients after approximately 2 months of CPAP use. Patients were grouped into CPAP adherence groups for ST (< 2 h, 2-4 h, and > 4 h) and LT adherence (< 4 h, > 4 h). Sleep architecture, sleep disordered breathing (SDB) indices, and daytime outcome variables from the diagnostic and titration NPSGs were compared between CPAP adherence groups. Results: There was a significant relationship between ST and LT CPAP adherence (r = 0.81, p < 0.001). Neither ST nor LT adherence were related to demographic variables, baseline severity of untreated SDB, sleep architecture, or measures of daytime impairment. Good CPAP adherence groups had significantly lower %N2 and greater %REM on the titration NPSG. A model combining change in sleep efficiency and change in sleep continuity between the diagnostic and titration NPSGs predicted 17% of the variance in LT adherence (p = 0.006). Conclusions: These findings demonstrate that characteristics of sleep architecture, even on the titration NPSG, may predict some of the variance in CPAP adherence. Better sleep quality on the titration night was related to better CPAP adherence, suggesting that interventions to improve sleep on/prior to the CPAP titration study might be used as a therapeutic intervention to improve CPAP adherence. Citation: Somiah M; Taxin Z; Keating J; Mooney AM; Norman RG; Rapoport DM; Ayappa I. Sleep quality, short-term and long-term CPAP adherence. J Clin Sleep Med 2012;8(5):489-500. PMID:23066359

Standardizing care and monitoring for anesthesia or procedural sedation delivered outside the operating room.

PubMed

Eichhorn, Volker; Henzler, Dietrich; Murphy, Michael F

2010-08-01

The purpose of this review is to summarize recommendations for the safe and efficient conductance of sedation and anesthesia at remote locations; and to define safety standards, monitoring techniques, quality of care and procedural eligibility. Anesthesia outside of the operating room is rapidly increasing in numbers, which has seen a growth of older and sicker patients. These circumstances have created a need for guidelines, for both specialist anesthesia providers and nonanesthesia-trained practitioners, that define patient selection, minimum monitoring (hemodynamics and respiration), facility design and equipment, policy framework, recovery facilities and policies. The patient's safety throughout all stages of sedation and/or anesthesia is the most pertinent goal. Recent data emphasize the importance of monitoring pulse oximetry and end-tidal carbon dioxide for any sedating or anesthetic procedure. Substandard monitoring combined with oversedation and subsequent respiratory depression are implicated as the main reasons for catastrophic sedation and anesthetic outcomes at remote locations. Patient selection, procedure appropriateness and location appropriateness are the key elements defining the provision of safe anesthesia care outside the operating room. Titratable, short-acting intravenous drugs are preferred such as propofol and remifentanil.

Semi-empirical proton binding constants for natural organic matter

NASA Astrophysics Data System (ADS)

Matynia, Anthony; Lenoir, Thomas; Causse, Benjamin; Spadini, Lorenzo; Jacquet, Thierry; Manceau, Alain

2010-03-01

Average proton binding constants ( KH,i) for structure models of humic (HA) and fulvic (FA) acids were estimated semi-empirically by breaking down the macromolecules into reactive structural units (RSUs), and calculating KH,i values of the RSUs using linear free energy relationships (LFER) of Hammett. Predicted log KH,COOH and log KH,Ph-OH are 3.73 ± 0.13 and 9.83 ± 0.23 for HA, and 3.80 ± 0.20 and 9.87 ± 0.31 for FA. The predicted constants for phenolic-type sites (Ph-OH) are generally higher than those derived from potentiometric titrations, but the difference may not be significant in view of the considerable uncertainty of the acidity constants determined from acid-base measurements at high pH. The predicted constants for carboxylic-type sites agree well with titration data analyzed with Model VI (4.10 ± 0.16 for HA, 3.20 ± 0.13 for FA; Tipping, 1998), the Impermeable Sphere model (3.50-4.50 for HA; Avena et al., 1999), and the Stockholm Humic Model (4.10 ± 0.20 for HA, 3.50 ± 0.40 for FA; Gustafsson, 2001), but differ by about one log unit from those obtained by Milne et al. (2001) with the NICA-Donnan model (3.09 ± 0.51 for HA, 2.65 ± 0.43 for FA), and used to derive recommended generic values. To clarify this ambiguity, 10 high-quality titration data from Milne et al. (2001) were re-analyzed with the new predicted equilibrium constants. The data are described equally well with the previous and new sets of values ( R2 ⩾ 0.98), not necessarily because the NICA-Donnan model is overparametrized, but because titration lacks the sensitivity needed to quantify the full binding properties of humic substances. Correlations between NICA-Donnan parameters are discussed, but general progress is impeded by the unknown number of independent parameters that can be varied during regression of a model fit to titration data. The high consistency between predicted and experimental KH,COOH values, excluding those of Milne et al. (2001), gives faith in the proposed semi-empirical structural approach, and its usefulness to assess the plausibility of proton stability constants derived from simulations of titration data.

Students' Cognitive Focus during a Chemistry Laboratory Exercise: Effects of a Computer-Simulated Prelab

ERIC Educational Resources Information Center

Winberg, T. Mikael; Berg, C. Anders R.

2007-01-01

To enhance the learning outcomes achieved by students, learners undertook a computer-simulated activity based on an acid-base titration prior to a university-level chemistry laboratory activity. Students were categorized with respect to their attitudes toward learning. During the laboratory exercise, questions that students asked their assistant…

Identification of Weak Acids and Bases by Titration with Primary Standards. A Modern Version of an Old Analytical Chemistry Experiment.

ERIC Educational Resources Information Center

Thompson, Robert Q.

1988-01-01

Describes a laboratory exercise in which acid dissociation constants and molecular weights are extracted from sample data and the sample is identified. Emphasizes accurate volumetric work while bringing to practice the concepts of acid-base equilibria, activity coefficients, and thermodynamic constants. (CW)

[Soil pH buffer capacity of tea garden with different planting years].

PubMed

Su, You-Jian; Wang, Ye-Jun; Zhang, Yong-Li; Luo, Yi; Sun, Li; Song, Li; Liao, Wan-You

2014-10-01

In order to investigate the effects of long-term tea planting on soil pH buffer capacity (pHBC), the variation of pHBC and its influence factors were investigated in tea gardens of 10, 15, 20, 25 and 30 years in Langxi and Qimen of Anhui Province. The results showed that the acid-base titration method was suitable for the determination of soil pHBC of tea gardens. The amount of acid-base added had approximate linear relationship with soil pH value in specific section (pH 4.0-6.0) of acid-base titration curves, so the soil pHBC could be calculated by linear regression equation. Soil pHBC in the tea gardens from the two regions showed a downward trend with increasing the planting years, which decreased at rates of 0.10 and 0.06 mmol · kg(-1) · a(-1) in Langxi and Qimen tea gardens, respectively. Soil pHBC had significant positive correlation with CEC, soil organic matter, base saturation and physical clay content, and significant negative correlation with exchangeable acid and exchange H+.

Analysis of titanium content in titanium tetrachloride solution

NASA Astrophysics Data System (ADS)

Bi, Xiaoguo; Dong, Yingnan; Li, Shanshan; Guan, Duojiao; Wang, Jianyu; Tang, Meiling

2018-03-01

Strontium titanate, barium titan and lead titanate are new type of functional ceramic materials with good prospect, and titanium tetrachloride is a commonly in the production such products. Which excellent electrochemical performance of ferroelectric tempreature coefficient effect.In this article, three methods are used to calibrate the samples of titanium tetrachloride solution by back titration method, replacement titration method and gravimetric analysis method. The results show that the back titration method has many good points, for example, relatively simple operation, easy to judgment the titration end point, better accuracy and precision of analytical results, the relative standard deviation not less than 0.2%. So, it is the ideal of conventional analysis methods in the mass production.

Determinations of Carbon Dioxide by Titration: New Experiments for General, Physical, and Quantitative Analysis Courses.

ERIC Educational Resources Information Center

Crossno, S. K.; And Others

1996-01-01

Presents experiments involving the analysis of commercial products such as carbonated beverages and antacids that illustrate the principles of acid-base reactions and present interesting problems in stoichiometry for students. (JRH)

The Computer Bulletin Board. Modified Gran Plots of Very Weak Acids on a Spreadsheet.

ERIC Educational Resources Information Center

Chau, F. T.; And Others

1990-01-01

Presented are two applications of computer technology to chemistry instruction: the use of a spreadsheet program to analyze acid-base titration curves and the use of database software to catalog stockroom inventories. (CW)

Ammonia Transporters and Their Role in Acid-Base Balance

PubMed Central

2017-01-01

Acid-base homeostasis is critical to maintenance of normal health. Renal ammonia excretion is the quantitatively predominant component of renal net acid excretion, both under basal conditions and in response to acid-base disturbances. Although titratable acid excretion also contributes to renal net acid excretion, the quantitative contribution of titratable acid excretion is less than that of ammonia under basal conditions and is only a minor component of the adaptive response to acid-base disturbances. In contrast to other urinary solutes, ammonia is produced in the kidney and then is selectively transported either into the urine or the renal vein. The proportion of ammonia that the kidney produces that is excreted in the urine varies dramatically in response to physiological stimuli, and only urinary ammonia excretion contributes to acid-base homeostasis. As a result, selective and regulated renal ammonia transport by renal epithelial cells is central to acid-base homeostasis. Both molecular forms of ammonia, NH3 and NH4+, are transported by specific proteins, and regulation of these transport processes determines the eventual fate of the ammonia produced. In this review, we discuss these issues, and then discuss in detail the specific proteins involved in renal epithelial cell ammonia transport. PMID:28151423

Correct titration of non-drugs and some other methodological issues.

PubMed

Beneke, M; Rasmus, W; Rød, I S; Fritze, J

1994-01-01

Doctors' prescription and dosing behaviour was investigated using data from 9 clinical trials in 550 patients treated with psychotropics. 7 trials were conducted under double- and 2 under single-blind conditions. In 3 of these trials, oral and i.m. preparations were used demanding a double-dummy design. All patients were evaluated on a weekly or 2-week basis using psychopathological rating scales (i.e. Hamilton Anxiety Scale, Hamilton Depression Scale, Clinical Global Impressions, Simpson and Angus EPS). It was found that (a) oral-medication titration was 3- to 4-fold more broad-ranging than i.m. medication titration, (b) oral placebo was titrated to the same extent as the oral investigational drugs, and (c) the titration schedule did not follow protocol requirements. Moreover, the average doses in all drug and placebo groups were the same. Concomitant medication like sleep inducers was found to be more closely related to doctors' habits than to actual medical need. Independent of trial and investigational drug, 10-33% of all patients received additional sleep inducers.

Multiple Diphtheria Antigen-Antibody Systems Investigated by Passive Haemagglutination Techniques and Other Methods

PubMed Central

Fulthorpe, A. J.

1962-01-01

A fair degree of correlation has been found between the in vivo antitoxin content of sera from horses immunized with crude Corynebacterium diphtheriae culture filtrates and the direct agglutinin titre of the sera when tested with sheep cells sensitized with diphtheria toxoid. Haemagglutination inhibition tests at the LA level of test with the same sera showed some rather large discrepancies from the in vivo and further tests with special agglutinin inhibiting toxins suggested that specific antitoxin free from other accessory antibodies might be non-agglutinating, and therefore not titratable by haemagglutination inhibition. The phosphate-stable, pepsin-stable and trypsin-stable antigens isolated from culture filtrates of C. diphtheriae were found to contain extremely small quantities of specific toxoid, and cross titration of each of the three antigen preparations showed that there was very little contamination by other antigens within the group. Absorption of diphtheria antiserum with red cells sensitized with each of the three accessory antigens individually, showed that the antibodies were highly specific and distinct. Absorption of diphtheria antiserum with a mixture of red cells sensitized with the three different antigens removed all demonstrable accessory antibodies, and the absorbed serum would no longer agglutinate cells sensitized with complete diphtheria toxoid. The absorbed serum, however, retained a large proportion of its neutralizing capacity for diphtheria toxin, when titrated in vivo. Titration of each of the accessory antibodies in a number of horse sera by haemagglutination inhibition demonstrated a correlation between the values for the accessory antibodies to the phosphate-stable and pepsin-stable antigens, but no correlation with the values for the antibody to the trypsin-stable antigen, when compared with results of the flocculation test. The relative proportions of diphtheria toxin and of the phosphate-stable and pepsin-stable antigens remained constant at all stages of purification of a filtrate including several recrystallization procedures. However, the concentration of the trypsin-stable antigen declined steadily during the process. The relative proportions of toxin, phosphate-stable and pepsin-stable antigens in several crude culture filtrates were constant under reasonable conditions of storage and very varied where deterioration had occurred. These three antigens also maintained a constant ratio in growing culture, the trypsin-stable antigen did not. PMID:13895880

An Ion-Selective Electrode for the Determination of Phencyclidine (PCP).

DTIC Science & Technology

1980-08-06

as an indicator_ ectrode in potentiometric titration of PCPA at concentrations DD 1473 EDITION or I Nov soIS OSSOOL TC SEPURqITY CLAWSFICATION Of...and ISE detection limits determined as described previous (25). The PCP electrode was used as the indicator electrode in potentiometric titrations of...was standardized by potentiometric titration with a dodecyltrimethyl- ammonium bromide (DoTAB) solution using a DoTA+ ISE (25) as the indicator

[Not Available].

PubMed

Burgot, J L

1978-04-01

Maleic, fumaric, tartaric, glutaric and adipic acids are titrated directly with sodium hydroxide by means of an automatic thermometric titrimeter. The titration curves have two break-points, corresponding to the successive neutralization of the two acid groups. Previous standardization permits measurement of the heats of neutralization, from which the enthalpies of dissociation can be deduced. From 0.3 to 1 mmole of acid can be titrated with a relative standard deviation of about 3%.

Use of vitreous carbon as a working electrode in coulometric titration of potassium hydrogen phthalate.

PubMed

Jennings, V J; Dodson, A; Tedds, G

1973-07-01

The use of a vitreous carbon electrode as a cathode in the amperostatic coulometric titration of aqueous potassium hydrogen phthalate solution is described. It is shown that 10 mg of the phthalate can be titrated with a precision better than 0.5%. Current-voltage curves for platinum and vitreous carbon cathodes show that there is an overpotential on the latter relative to the former.

A stable and convenient protein electrophoresis titration device with bubble removing system.

PubMed

Zhang, Qiang; Fan, Liu-Yin; Li, Wen-Lin; Cong, Feng-Song; Zhong, Ran; Chen, Jing-Jing; He, Yu-Chen; Xiao, Hua; Cao, Cheng-Xi

2017-07-01

Moving reaction boundary titration (MRBT) has a potential application to immunoassay and protein content analysis with high selectivity. However, air bubbles often impair the accuracy of MRBT, and the leakage of electrolyte greatly decreases the safety and convenience of electrophoretic titration. Addressing these two issues a reliable MRBT device with modified electrolyte chamber of protein titration was designed. Multiphysics computer simulation was conducted for optimization according to two-phase flow. The single chamber was made of two perpendicular cylinders with different diameters. After placing electrophoretic tube, the resident air in the junction next to the gel could be eliminated by a simple fast electrolyte flow. Removing the electrophoretic tube automatically prevented electrolyte leakage at the junction due to the gravity-induced negative pressure within the chamber. Moreover, the numerical simulation and experiments showed that the improved MRBT device has following advantages: (i) easy and rapid setup of electrophoretic tube within 20 s; (ii) simple and quick bubble dissipates from the chamber of titration within 2 s; (iii) no electrolyte leakage from the two chambers: and (iv) accurate protein titration and safe instrumental operation. The developed technique and apparatus greatly improves the performance of the previous MRBT device, and providing a new route toward practical application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of a gel microcolumn assay with the conventional tube test for red blood cell alloantibody titration.

PubMed

Finck, Rachel; Lui-Deguzman, Carrie; Teng, Shih-Mao; Davis, Rebecca; Yuan, Shan

2013-04-01

Titration is a semiquantitative method used to estimate red blood cell (RBC) alloantibody reactivity. The conventional tube test (CTT) technique is the traditional method for performing titration studies. The gel microcolumn assay (GMA) is also a sensitive method to detect RBC alloantibodies. The aim of this study was to compare a GMA with the CTT technique in the performance of Rh and K alloantibody titration. Patient serum samples that contained an RBC alloantibody with a singular specificity were identified by routine blood bank workflow. Parallel titration studies were performed on these samples by both the CTT method and a GMA (ID-Micro Typing System anti-IgG gel card, Micro Typing Systems, Inc., an Ortho-Clinical Diagnostics Company). Forty-eight samples were included, including 11 anti-D, five anti-c, 13 anti-E, one anti-C, three anti-e, and 15 anti-K. Overall, the two methods generated identical results in 21 of 48 samples. For 42 samples (87.5%) the two methods generated results that were within one serial dilution, and for the remaining six samples, results were within two dilutions. GMA systems may perform comparably to the CTT in titrating alloantibodies to Rh and Kell antigens. © 2012 American Association of Blood Banks.

Down-titration of biologics for the treatment of rheumatoid arthritis: a systematic literature review.

PubMed

Lau, Chak Sing; Gibofsky, Allan; Damjanov, Nemanja; Lula, Sadiq; Marshall, Lisa; Jones, Heather; Emery, Paul

2017-11-01

Biologic therapies have improved the management of rheumatoid arthritis (RA) and the treat-to-target approach has resulted in many patients achieving remission. In the current treatment landscape, clinicians have begun considering dose reduction/tapering for their patients. Rheumatology guidelines in Asia, Europe, and the United States include down-titration of biologics but admit that the level of evidence is moderate. We conducted a systematic literature review to assess the published studies that evaluate down-titration of biologics in RA. The published literature was searched for studies that down-titrated the following biologics: abatacept, adalimumab, certolizumab, etanercept, golimumab, infliximab, rituximab, and tocilizumab. Eligible studies included randomized controlled trials (RCTs), non-RCTs, observational, and pharmacoeconomic studies. The outcomes of interest were (1) efficacy and health-related quality of life, (2) disease flares, and (3) impact on cost. Eleven full-text publications were identified; only three were RCTs. Study results suggest that dosing down may be an option in many patients who have achieved remission or low disease activity. However, some patients are likely to experience a disease flare. Across the studies, the definition of disease flare and the down-titration criteria were inconsistent, making it difficult to conclude which patients may be appropriate and when to attempt down-titration. Studies have evaluated the practice of dosing down biologic therapy in patients with RA; however, a relatively small number of RCTs have been published. Although down-titration may be an option for some patients in LDA or remission, additional RCTs are needed to provide guidance on this practice.

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

NASA Astrophysics Data System (ADS)

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

2014-02-01

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

Macromolecular Competition Titration Method: Accessing Thermodynamics of the Unmodified Macromolecule–Ligand Interactions Through Spectroscopic Titrations of Fluorescent Analogs

PubMed Central

Bujalowski, Wlodzimierz; Jezewska, Maria J.

2011-01-01

Analysis of thermodynamically rigorous binding isotherms provides fundamental information about the energetics of the ligand–macromolecule interactions and often an invaluable insight about the structure of the formed complexes. The Macromolecular Competition Titration (MCT) method enables one to quantitatively obtain interaction parameters of protein–nucleic acid interactions, which may not be available by other methods, particularly for the unmodified long polymer lattices and specific nucleic acid substrates, if the binding is not accompanied by adequate spectroscopic signal changes. The method can be applied using different fluorescent nucleic acids or fluorophores, although the etheno-derivatives of nucleic acid are especially suitable as they are relatively easy to prepare, have significant blue fluorescence, their excitation band lies far from the protein absorption spectrum, and the modification eliminates the possibility of base pairing with other nucleic acids. The MCT method is not limited to the specific size of the reference nucleic acid. Particularly, a simple analysis of the competition titration experiments is described in which the fluorescent, short fragment of nucleic acid, spanning the exact site-size of the protein–nucleic acid complex, and binding with only a 1:1 stoichiometry to the protein, is used as a reference macromolecule. Although the MCT method is predominantly discussed as applied to studying protein–nucleic acid interactions, it can generally be applied to any ligand–macromolecule system by monitoring the association reaction using the spectroscopic signal originating from the reference macromolecule in the presence of the competing macromolecule, whose interaction parameters with the ligand are to be determined. PMID:21195223

Clozapine for Drug-Refractory Irritability in Individuals with Developmental Disability.

PubMed

Wink, Logan K; Badran, Ismail; Pedapati, Ernest V; Sorensen, Rena; Benton, Stacy C; Johnson, Mark C; Wissel, Gregory; Erickson, Craig A

2016-11-01

In this case series, we describe the acute clinical impact and tolerability of rapid titration of clozapine for treatment of refractory irritability in five hospitalized youth with developmental disability. We offer this descriptive report in an effort to expand the evidence base guiding treatment of refractory aggression in this population. Five youth with developmental disability and severe irritability were admitted to a 10-bed psychiatric crisis stabilization unit where they received thorough psychiatric and medical evaluation. Informed consent was obtained in each case, and each patient underwent rapid titration onto clozapine. Clozapine monitoring guidelines were followed for all patients throughout treatment, and clinical severity at baseline and improvement with treatment was measured by use of the Clinical Global Impressions-Severity scale (CGI-S) and the Clinical Global Impressions-Improvement scale (CGI-I). One female and four males diagnosed with developmental disability and at least one other psychiatric diagnosis, mean age of 13.1 ± 2.1 years, and mean CGI-S at baseline of 5.8, each received clozapine treatment by rapid titration. The mean therapeutic total daily dose of clozapine was 380 ± 200 mg. All patients demonstrated acute clinical improvement with the mean final CGI-I of 2.0, or "much improved." These initial results support the potential utility of clozapine rapid titration for treatment of severe refractory irritability in youth with developmental disability. These patients tolerated clozapine treatment in the short term. Future studies are needed to thoroughly evaluate the long-term safety of clozapine treatment in this population.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sukri, Shahratul Ain Mohd; Heng, Lee Yook; Karim, Nurul Huda Abd

A platinum (II) salphen complex was synthesised by condensation reaction of 2,4-dihydroxylbenzaldehyde and o-phenylenediamine with potassium tetrachloroplatinate to obtain N,N′-Bis-4-(hydroxysalicylidene)-phenylenediamine-platinum (II). The structure of the complex was confirmed by {sup 1}H and {sup 13}C NMR spectroscopy, FTIR spectroscopy, CHN elemental analyses and ESI-MS spectrometry. The platinum (II) salphen complex with four donor atoms N{sub 2}O{sub 2} from its salphen ligand coordinated to platinum (II) metal centre were determined. The binding mode and interaction of this complex with calf thymus DNA was determined by UV/Vis DNA titration and emission titration. The intercalation between the DNA bases by π-π stacking due tomore » its square planar geometry and aromatic rings structures was proposed.« less

Proposal for a new protein therapeutic immunogenicity titer assay cutpoint.

PubMed

Wakshull, Eric; Hendricks, Robert; Amaya, Caroline; Coleman, Daniel

2011-12-01

Generally, immunogenicity assessment strategies follow this assay triage schema: screen→confirm→titer. Each requires the determination of a threshold value (cutpoint) for decision making. No guidance documents exist for the determination of a specific titration assay cutpoint. The default practice is to use the screening assay cutpoint, frequently leading to controls or samples not reaching this cutpoint. We propose a method for determination of a titration cutpoint based upon the variance of the negative-control sample. Positive-control samples that did not cross a screening cutpoint did cross the titer cutpoint, albeit generating slightly lower titer values. Our approach is consistent with the statistical methods currently recommended for the screening and confirmatory assay cutpoints and is operationally simple and efficient.

Prophylactic Therapy for Hereditary Angioedema.

PubMed

Longhurst, Hilary; Zinser, Emily

2017-08-01

Long-term prophylaxis is needed in many patients with hereditary angioedema and poses many challenges. Attenuated androgens are effective in many but are limited by side effect profiles. There is less evidence for efficacy of tranexamic acid and progestagens; however, the small side effect profile makes tranexamic acid an option for prophylaxis in children and progestagens an option for women. C1 inhibitor is beneficial, but at present requires intravenous delivery and may need dose titration for maximum efficacy. Short-term prophylaxis should be considered for all procedures. New therapies are promising in overcoming many problems encountered with current options for long-term prophylaxis. Copyright © 2017 Elsevier Inc. All rights reserved.

Cannabinoids concentration variability in cannabis olive oil galenic preparations.

PubMed

Carcieri, Chiara; Tomasello, Cristina; Simiele, Marco; De Nicolò, Amedeo; Avataneo, Valeria; Canzoneri, Luca; Cusato, Jessica; Di Perri, Giovanni; D'Avolio, Antonio

2018-01-01

Knowledge of the exact concentration of active compounds in galenic preparations is crucial to be able to ensure their quality and to properly administer the prescribed dose. Currently, the need for titration of extracts is still debated. Considering this, together with the absence of a standard preparation method, the aim of this study was to evaluate cannabinoids concentrations variability in galenic olive oil extracts, to evaluate the interlot and interlaboratory variability in the extraction yield and in the preparation composition. Two hundred and one extracts (123 (61.2%) from Bedrocan ® , 54 (26.9%) from Bediol ® , 11 (5.5%) from Bedrolite ® , and 13 (6.5%) from mixed preparations) were analysed by liquid chromatography coupled with tandem mass spectrometry, quantifying cannabinoids (THC, CBD, THCA, CBDA and CBN) concentrations. The RSD% of THC and CBD concentrations resulted higher than 50%. Specifically for Bedrocan ® , Bediol ® , Bedrolite ® (5 g/50 ml), these were THC 82%, THC 53% and CBD 91%, THC 58% and CBD 59%, respectively. The median extraction yields were greater than 75% for all preparations. Our results highlighted a wide variability in THC and CBD concentrations that justify the need for titration and opens further questions about other pharmaceutical preparations without regulatory indication for this procedure. © 2017 Royal Pharmaceutical Society.

Grafting the surface of carbon nanotubes and carbon black with the chemical properties of hyperbranched polyamines

NASA Astrophysics Data System (ADS)

Morales-Lara, Francisco; Domingo-García, María; López-Garzón, Rafael; Luz Godino-Salido, María; Peñas-Sanjuán, Antonio; López-Garzón, F. Javier; Pérez-Mendoza, Manuel; Melguizo, Manuel

2016-01-01

Controlling the chemistry on the surface of new carbon materials is a key factor to widen the range of their applicability. In this paper we show a grafting methodology of polyalkylamines to the surface of carbon nanomaterials, in particular, carbon nanotubes and a carbon black. The aim of this work is to reach large degrees of covalent functionalization with hyperbranched polyethyleneimines (HBPEIs) and to efficiently preserve the strong chelating properties of the HBPEIs when they are fixed to the surface of these carbon materials. This functionalization opens new possibilities of using these carbon nanotubes-based hybrids. The results show that the HBPEIs are covalently attached to the carbon materials, forming hybrids. These hybrids emerge from the reaction of amine functions of the HBPEIs with carbonyls and carboxylic anhydrides of the carbon surface which become imine and imide bonds. Thus, due to the nature of these bonds, the pre-oxidized samples with relevant number of C=O groups showed an increase in the degree of functionalization with the HBPEIs. Furthermore, both the acid-base properties and the coordination capacity for metal ions of the hybrids are equivalent to that of the free HBPEIs in solution. This means that the chemical characteristics of the HBPEIs have been efficiently transferred to the hybrids. To reach this conclusion we have developed a novel procedure to assess the acid-base and the coordination properties of the hybrids (solids) by means of potentiometric titration. The good agreement of the values obtained for the hybrids and for the free HBPEIs in aqueous solution supports the reliability of the procedure. Moreover, the high capacity of the hybrids to capture Ni2+ by complexation opens new possibilities of using these hybrids to capture high-value metal ions such as Pd2+ and Pt2+.

The Thermodynamics of the Carbonate System in Seawater,

DTIC Science & Technology

1979-03-08

ionization of water at various water by potentiometric titration . Deep-Sea Res. 17, temperatures from molal volume data. J. Soln. Chem. 737-750. 1... titration alkalinity, AT, givcn by not available at low salinities and molal volume cal- A, = [HCO/] + 2[CO2-] + [B(OH-] culations (MILLERO et al...used to characterize obtained by a computer titration improves, pH the parameters of the carbonate system in seawater. measurements should be made. This

The Velocity of Sound in Sea Water at Zero Depth

DTIC Science & Technology

1952-06-11

the Woods Hole Oceanographic Institution. Toward the end of this investigation a potentiometric titration with the Beckman automatic titratcr and a...Interferon eter as soon as received, and at Intervals throughout the investigation. Ch!orlnitie3 were determined by the Mohr method of AgNOi titration ...chlorinity of each of the solutions was actually determined by Mohr titration in the sar.? manner as the chiorinities of the original samples. The

Acid-Base Homeostasis

PubMed Central

Nakhoul, Nazih; Hering-Smith, Kathleen S.

2015-01-01

Acid-base homeostasis and pH regulation are critical for both normal physiology and cell metabolism and function. The importance of this regulation is evidenced by a variety of physiologic derangements that occur when plasma pH is either high or low. The kidneys have the predominant role in regulating the systemic bicarbonate concentration and hence, the metabolic component of acid-base balance. This function of the kidneys has two components: reabsorption of virtually all of the filtered HCO3− and production of new bicarbonate to replace that consumed by normal or pathologic acids. This production or generation of new HCO3− is done by net acid excretion. Under normal conditions, approximately one-third to one-half of net acid excretion by the kidneys is in the form of titratable acid. The other one-half to two-thirds is the excretion of ammonium. The capacity to excrete ammonium under conditions of acid loads is quantitatively much greater than the capacity to increase titratable acid. Multiple, often redundant pathways and processes exist to regulate these renal functions. Derangements in acid-base homeostasis, however, are common in clinical medicine and can often be related to the systems involved in acid-base transport in the kidneys. PMID:26597304

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

PubMed

Wang, X; Ma, Y; Su, Y

1997-09-01

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 can behave like surface Brönsted acid-base sites due to coordination of environmental H2O molecules. The method was applied to 18 diverse alga species (including 7 diatoms, 2 flagellates, 8 green algae and 1 red alga) maintained in seawater cultures. For the species examined, the surface areas of individual cells ranged from 2.8 x 10(-8) m2 for Nannochloropsis oculata to 690 x 10(-8) m2 for Dunaliella viridis, specific surface areas from 1,030 m2.g-1 for Dunaliella salina to 28,900 m2.g-1 for Pyramidomonas sp. Measurement accuracy was 15.2%. Preliminary studies show that the method may be more promising and accurate than light/electron microscopic measurements for coarse estimation of the surface area of living algae.

Turn on ESPT: novel salicylaldehyde based sensor for biological important fluoride sensing.

PubMed

Liu, Kai; Zhao, Xiaojun; Liu, Qingxiang; Huo, Jianzhong; Fu, Huifang; Wang, Ying

2014-09-05

A novel and simple salicylaldehyde based anion fluorescent sensor 1 has been designed, which can selectively sense fluoride by 'turn on' excited-state intermolecular proton transfer (ESPT). The binding constant and the stoichiometry were obtained by non-linear least-square analysis of the titration curves. Copyright © 2014 Elsevier B.V. All rights reserved.

A mRNA-Responsive G-Quadruplex-Based Drug Release System

PubMed Central

Yaku, Hidenobu; Murashima, Takashi; Miyoshi, Daisuke; Sugimoto, Naoki

2015-01-01

G-quadruplex-based drug delivery carriers (GDDCs) were designed to capture and release a telomerase inhibitor in response to a target mRNA. Hybridization between a loop on the GDDC structure and the mRNA should cause the G-quadruplex structure of the GDDC to unfold and release the bound inhibitor, anionic copper(II) phthalocyanine (CuAPC). As a proof of concept, GDDCs were designed with a 10-30-mer loop, which can hybridize with a target sequence in epidermal growth factor receptor (EGFR) mRNA. Structural analysis using circular dichroism (CD) spectroscopy showed that the GDDCs form a (3 + 1) type G-quadruplex structure in 100 mM KCl and 10 mM MgCl2 in the absence of the target RNA. Visible absorbance titration experiments showed that the GDDCs bind to CuAPC with Ka values of 1.5 × 105 to 5.9 × 105 M−1 (Kd values of 6.7 to 1.7 μM) at 25 °C, depending on the loop length. Fluorescence titration further showed that the G-quadruplex structure unfolds upon binding to the target RNA with Ka values above 1.0 × 108 M−1 (Kd values below 0.01 μM) at 25 °C. These results suggest the carrier can sense and bind to the target RNA, which should result in release of the bound drug. Finally, visible absorbance titration experiments demonstrated that the GDDC release CuAPC in response to the target RNA. PMID:25905703

Characterization of acid-base properties of two gibbsite samples in the context of literature results.

PubMed

Adekola, F; Fédoroff, M; Geckeis, H; Kupcik, T; Lefèvre, G; Lützenkirchen, J; Plaschke, M; Preocanin, T; Rabung, T; Schild, D

2011-02-01

Two different gibbsites, one commercial and one synthesized according to a frequently applied recipe, were studied in an interlaboratory attempt to gain insight into the origin of widely differing reports on gibbsite acid-base surface properties. In addition to a thorough characterization of the two solids, several methods relevant to the interfacial charging were applied to the two samples: potentiometric titrations to obtain the "apparent" proton related surface charge density, zeta-potential measurements characterizing the potential at the plane of shear, and Attenuated Total Reflection Infrared Spectroscopy (ATR-IR) to obtain information on the variation of counter-ion adsorption with pH (using nitrate as a probe). Values of the IEP at 9-10 and 11.2-11.3 were found for the commercial and synthesized sample, respectively. The experimental observations revealed huge differences in the charging behavior between the two samples. Such differences also appeared in the titration kinetics. A detailed literature review revealed similar disparity with no apparent systematic trend. While previously the waiting time between additions had been advocated to explain such differences among synthesized samples, our results do not support such a conclusion. Instead, we find that the amount of titrant added in each aliquot appears to have a significant influence on the titration curves. While we can relate a number of observations to others, a number of open questions and contradictions remain. We suggest various processes, which can explain the observed behavior. Copyright © 2010 Elsevier Inc. All rights reserved.

Acid-base properties of humic substances from composted and thermally-dried sewage sludges and amended soils as determined by potentiometric titration and the NICA-Donnan model.

PubMed

Fernández, José M; Plaza, César; Senesi, Nicola; Polo, Alfredo

2007-09-01

The acid-base properties of humic acids (HAs) and fulvic acids (FAs) isolated from composted sewage sludge (CS), thermally-dried sewage sludge (TS), soils amended with either CS or TS at a rate of 80 t ha(-1)y(-1) for 3y and the corresponding unamended soil were investigated by use of potentiometric titrations. The non-ideal competitive adsorption (NICA)-Donnan model for a bimodal distribution of proton binding sites was fitted to titration data by use of a least-squares minimization method. The main fitting parameters of the NICA-Donnan model obtained for each HA and FA sample included site densities, median affinity constants and widths of affinity distributions for proton binding to low and high affinity sites, which were assumed to be, respectively, carboxylic- and phenolic-type groups. With respect to unamended soil HA and FA, the HAs and FAs from CS, and especially TS, were characterized by smaller acidic functional group contents, larger proton binding affinities of both carboxylic- and phenolic-type groups, and smaller heterogeneity of carboxylic and phenolic-type groups. Amendment with CS or TS led to a decrease of acidic functional group contents and a slight increase of proton binding affinities of carboxylic- and phenolic-type groups of soil HAs and FAs. These effects were more evident in the HA and FA fractions from CS-amended soil than in those from TS-amended soil.

Acid-base properties of the surface of the α-Al2O3 suspension

NASA Astrophysics Data System (ADS)

Ryazanov, M. A.; Dudkin, B. N.

2009-12-01

The distribution of the acid-base centers on the surface of α-Al2O3 suspension particles was studied by potentiometric titration, and the corresponding p K spectra were constructed. It was inferred that the double electric layer created by the supporting electrolyte substantially affected the screening of the acid-base centers on the particle surface of the suspension.

Complexity in Acid–Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

PubMed Central

Malm, Christian; Kim, Heejae; Wagner, Manfred

2017-01-01

Abstract Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid–base aggregates challenging. Here, we track such acid–base interactions over a broad range of relative compositions between diphenyl phosphoric acid and the base quinaldine in dichloromethane, by using a combination of dielectric relaxation and NMR spectroscopy. In contrast to what one would expect for an acid–base titration, we find strong deviations from quantitative proton transfer from the acid to the base. Even for an excess of the base, multimers consisting of one base and at least two acid molecules are formed, in addition to the occurrence of proton transfer from the acid to the base and simultaneous formation of ion pairs. For equimolar mixtures such multimers constitute about one third of all intermolecular aggregates. Quantitative analysis of our results shows that the acid‐base association constant is only around six times larger than that for the acid binding to an acid‐base dimer, that is, to an already protonated base. Our findings have implications for the interpretation of previous studies of reactive intermediates in organocatalysis and provide a rationale for previously observed nonlinear effects in phosphoric acid catalysis. PMID:28597513

Clinical Outcomes of Continuation of Metformin Titration Instructions with Electronic Prescribing.

PubMed

Delate, Thomas; Rader, Nathan; Rawlings, Julia E; Smith, Karen; Herner, Sheryl J

2015-06-01

Anecdotal evidence suggests that metformin titration instructions are not being updated and refill requests are approved without modification of the titration instructions such that the titration instructions is continued for patients newly initiated on metformin. This was a retrospective cohort analysis of adult patients who received newly initiated metformin pharmacotherapy. Patients were followed from their initial metformin purchase through two subsequent metformin refill purchases. Outcomes, including the 3-year incidence rate of patients with at least one set of continued titration instructions and proportions of patients with at least one gastrointestinal adverse effect (AE) and those with an elevated glucose measurement at follow-up, were assessed during the time period between patients' second and third metformin purchases. Analyses were performed comparing the exposure (i.e., patients with continued instructions) group to the control (i.e., patients without continued instructions) group. The exposure group had a higher mean age and chronic disease score but lower metformin starting dose than the control group (all p < 0.05). The 3-year incidence rate of patients with at least one continuation of titration instructions was 60.3 % (95 % CI 58.3-62.3). Gastrointestinal AEs were rare with equivalent proportions of patients in each group experiencing an event (p > 0.05). Control patients (48.7 % of patients with a measurement) were more likely to have had poorly controlled glucose than exposure patients (35.7 % of patients with a measurement) (p < 0.001). A high rate of continuation of titration instructions for patients newly initiated on metformin was observed; however, such continuation did not negatively affect clinical outcomes.

Barriers to Beta-Blocker Use and Up-Titration Among Patients with Heart Failure with Reduced Ejection Fraction.

PubMed

Levitan, Emily B; Van Dyke, Melissa K; Loop, Matthew Shane; O'Beirne, Ronan; Safford, Monika M

2017-12-01

For patients with heart failure with reduced ejection fraction (HFrEF), guidelines recommend use of beta-blockers with gradual up-titration. However, many patients with HFrEF do not use beta-blockers and up-titration is rare. Our purpose was to identify and rank barriers to beta-blocker use and up-titration from the perspective of primary care physicians. We conducted 4 moderated, structured group discussions among 19 primary care physicians using the nominal group technique; 16 participants also completed a survey. Participants generated lists of barriers to beta-blocker use and up-titration among patients with HFrEF. Each participant had six votes with three votes assigned to the item ranked most important, two to the second most important item, and one to the third most important item. Investigators characterized items into themes. The percentage of available votes was calculated for each theme. Fifteen of 16 participating primary care physicians who completed the survey reported that management of beta-blockers was their responsibility. Treatment/side effects, particularly hypotension, were identified as the most important barrier for beta-blocker use (72% of available votes) followed by polypharmacy (11%), healthcare system barriers (10%), and comorbidities (6%). Barriers to up-titration included treatment/side effects (49% of available votes), patient communication/buy-in (21%), polypharmacy (13%), and healthcare system barriers (8%). Many barriers to guideline concordant use of beta-blockers among patients with HFrEF identified by primary care providers are not readily modifiable. Addressing these barriers may require development, testing, and dissemination of protocols for beta-blocker initiation and up-titration that are safe and appropriate in primary care.

Predicting prolonged dose titration in patients starting warfarin.

PubMed

Finkelman, Brian S; French, Benjamin; Bershaw, Luanne; Brensinger, Colleen M; Streiff, Michael B; Epstein, Andrew E; Kimmel, Stephen E

2016-11-01

Patients initiating warfarin therapy generally experience a dose-titration period of weeks to months, during which time they are at higher risk of both thromboembolic and bleeding events. Accurate prediction of prolonged dose titration could help clinicians determine which patients might be better treated by alternative anticoagulants that, while more costly, do not require dose titration. A prediction model was derived in a prospective cohort of patients starting warfarin (n = 390), using Cox regression, and validated in an external cohort (n = 663) from a later time period. Prolonged dose titration was defined as a dose-titration period >12 weeks. Predictor variables were selected using a modified best subsets algorithm, using leave-one-out cross-validation to reduce overfitting. The final model had five variables: warfarin indication, insurance status, number of doctor's visits in the previous year, smoking status, and heart failure. The area under the ROC curve (AUC) in the derivation cohort was 0.66 (95%CI 0.60, 0.74) using leave-one-out cross-validation, but only 0.59 (95%CI 0.54, 0.64) in the external validation cohort, and varied across clinics. Including genetic factors in the model did not improve the area under the ROC curve (0.59; 95%CI 0.54, 0.65). Relative utility curves indicated that the model was unlikely to provide a clinically meaningful benefit compared with no prediction. Our results suggest that prolonged dose titration cannot be accurately predicted in warfarin patients using traditional clinical, social, and genetic predictors, and that accurate prediction will need to accommodate heterogeneities across clinical sites and over time. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Entire-Dataset Analysis of NMR Fast-Exchange Titration Spectra: A Mg2+ Titration Analysis for HIV-1 Ribonuclease H Domain.

PubMed

Karki, Ichhuk; Christen, Martin T; Spiriti, Justin; Slack, Ryan L; Oda, Masayuki; Kanaori, Kenji; Zuckerman, Daniel M; Ishima, Rieko

2016-12-15

This article communicates our study to elucidate the molecular determinants of weak Mg 2+ interaction with the ribonuclease H (RNH) domain of HIV-1 reverse transcriptase in solution. As the interaction is weak (a ligand-dissociation constant >1 mM), nonspecific Mg 2+ interaction with the protein or interaction of the protein with other solutes that are present in the buffer solution can confound the observed Mg 2+ -titration data. To investigate these indirect effects, we monitored changes in the chemical shifts of backbone amides of RNH by recording NMR 1 H- 15 N heteronuclear single-quantum coherence spectra upon titration of Mg 2+ into an RNH solution. We performed the titration under three different conditions: (1) in the absence of NaCl, (2) in the presence of 50 mM NaCl, and (3) at a constant 160 mM Cl - concentration. Careful analysis of these three sets of titration data, along with molecular dynamics simulation data of RNH with Na + and Cl - ions, demonstrates two characteristic phenomena distinct from the specific Mg 2+ interaction with the active site: (1) weak interaction of Mg 2+ , as a salt, with the substrate-handle region of the protein and (2) overall apparent lower Mg 2+ affinity in the absence of NaCl compared to that in the presence of 50 mM NaCl. A possible explanation may be that the titrated MgCl 2 is consumed as a salt and interacts with RNH in the absence of NaCl. In addition, our data suggest that Na + increases the kinetic rate of the specific Mg 2+ interaction at the active site of RNH. Taken together, our study provides biophysical insight into the mechanism of weak metal interaction on a protein.

Barriers to and enablers of insulin self-titration in adults with Type 2 diabetes: a qualitative study.

PubMed

McBain, H; Begum, S; Rahman, S; Mulligan, K

2017-02-01

To identify the barriers to and enablers of effective insulin self-titration in people with Type 2 diabetes. A qualitative semi-structured interview approach was used. Questions were structured according to the Theoretical Domains Framework, which outlines 14 domains that can act as barriers to and enablers of changing behaviour. Interviews were audio-recorded and transcribed verbatim. The data were coded according to the 14 domains, belief statements were created within each domain, and a frequency count of the most reported barriers and enablers was then carried out. Analyses were conducted by two researchers, and discrepancies agreed with a third researcher. A total of 18 adults with Type 2 diabetes took part in an interview. The majority were of South-Asian ethnicity (n = 8) and were men (n = 12). Their mean age was 61 years old. The mean duration of diabetes was 16 years and time on insulin 9 years. Inter-rater reliability for each of the domains varied (29-100%). The most frequently reported domains were Social Influence and Beliefs about Consequences; the least frequently reported were Optimism and Reinforcement. Interviewees reported receiving support to self-titrate from a range of sources. Self-titrating was perceived to have a range of both positive and negative consequences, as was not titrating. The findings highlight that those interviewed experienced a range of barriers and enablers when attempting to self-titrate. Improved education and training when initiating insulin treatment among adults with Type 2 diabetes, and throughout their journey on insulin therapy could help identify and address these barriers in order to optimize self-titration. © 2016 Diabetes UK.

Labeling Cells with Silver/Dendrimer Nanocomposites

DTIC Science & Technology

2005-01-01

used in further studies without additional purification. Potentiometric titrations were performed manually, under nitrogen atmosphere, at room...transmits light between 465 and 485 nm. Results and Discussion Figure IA presents potentiometric titration curves of Ag+-PAMAM_E5.NH 2 systems mixed at 15:1... Potentiometric titration curves of PAMAM_E5.NH 2 (circles) Ag+-PAMAME5.NH 2 30:1 (squares) and Ag+-PAMAME5.NH2 45:1 systems (triangles). B - UV-vis spectra of UV

Molecular Weight Measurement of Biobased Furan Polyamides via Non-Aqueous Potentiometric Titration

DTIC Science & Technology

2013-06-01

electromagnetic fields, all titrations were completed in a chemical hood, which acted as a Faraday cage (a shield used to blocks external static and...while using DMF as a solvent. Additionally, no Faraday cage was used in the experimental setup, so the titrations were conducted inside the chemical...monomer was becoming more soluble in glacial acetic acid and the amount of chlorobenzene had less of an effect on the solution properties (i.e