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Sample records for group contributed titration

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

    Science.gov (United States)

    Ebling, A. M.; Schijf, J.

    2008-12-01

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

  2. The origin of multiply sigmoid curves of pH-dependence. The partitioning of groups among titration pK values.

    Science.gov (United States)

    Dixon, H B; Clarke, S D; Smith, G A; Carne, T K

    1991-08-15

    An acid, HnA, with n ionizing groups is known to have the same titration curve as an equimolar mixture of n hypothetical monobasic acids, whose dissociation constants are known as the 'titration constants' of the real acid. We show that the pH-dependence of any property of HnA is also represented by the sum of one-site titration curves, characterized by these same titration constants. Since one such property is the degree of dissociation of one of the dissociating groups, a fraction of each group shows each of the various titration pK values, so that the group partitions among them. The n groups therefore share the same n titration pK values but differ in the fractions belonging to each. The one H+ ion per molecule that titrates with each pK is thus made up of the fractions, one from each group, that share this pK value. A group may possess a single pK value, in that it contributes virtually all of this pK and almost nothing to the others, only if either (1) in titrates in a different pH range from the other groups or (2) its affinity for H+ is unaffected by their ionization state.

  3. Assessing Contributions to Group Assignments

    Science.gov (United States)

    Johnston, Lucy; Miles, Lynden

    2004-01-01

    We report the use of a combination of self- and peer-assessment in an undergraduate social psychology laboratory course. Students worked in small groups on a self-directed empirical project that they each wrote up independently as a laboratory report. Marks for the written assignment were moderated by a contribution index measure based on the…

  4. Titratable Acidity and Alkalinity of Red Soil Surfaces

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; HEQUN; 等

    1993-01-01

    The surfaces of red soils have an apparent amphoteric character,carrying titratable acidity and titratable alkalinity simultaneously.The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxide-type surfaces and dissociation of weak-acid functional groups of soil organic matter,while the titratable alkalinity is derived from release of hydroxyl groups of hydrous oxide-type surfaces.The titratable acidity and titratable alkalinity mainly depended on the composition and content of iron and aluminum oxides in the soils.The results showed that the titratable acidity and titratable alkalinity were in significantly positive correlation not only with the content of amorphous aluminum oxide(Alo) and iron oxide(Feo) extracted with acid ammonium oxalate solution,free iron oxide(Fed) extracted with sodium dithionite-citrate-bicarbonate(DCB) and clays,but also with the zero point of charge (ZPC) of the samples.Organic matter made an important contribution to the titratable acidity.the titratable alkalinity was closely correlated with the amount of fluoride ions adsorbed.The titratable acidity and titratable alkalinity of red soils were influenced by parent materials,being in the order of red soil derived from basalt> that from tuff> that from granite.The titratable acidity and titratable alkalinity ware closely related with origination of the variable charges of red soils,and to a certain extent were responsible for variable negative and positive charges of the soils.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Black, Stuart; Ferrell, Jack R.

    2017-01-01

    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 degrees C.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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)

  9. Group Contribution Methods for Phase Equilibrium Calculations.

    Science.gov (United States)

    Gmehling, Jürgen; Constantinescu, Dana; Schmid, Bastian

    2015-01-01

    The development and design of chemical processes are carried out by solving the balance equations of a mathematical model for sections of or the whole chemical plant with the help of process simulators. For process simulation, besides kinetic data for the chemical reaction, various pure component and mixture properties are required. Because of the great importance of separation processes for a chemical plant in particular, a reliable knowledge of the phase equilibrium behavior is required. The phase equilibrium behavior can be calculated with the help of modern equations of state or g(E)-models using only binary parameters. But unfortunately, only a very small part of the experimental data for fitting the required binary model parameters is available, so very often these models cannot be applied directly. To solve this problem, powerful predictive thermodynamic models have been developed. Group contribution methods allow the prediction of the required phase equilibrium data using only a limited number of group interaction parameters. A prerequisite for fitting the required group interaction parameters is a comprehensive database. That is why for the development of powerful group contribution methods almost all published pure component properties, phase equilibrium data, excess properties, etc., were stored in computerized form in the Dortmund Data Bank. In this review, the present status, weaknesses, advantages and disadvantages, possible applications, and typical results of the different group contribution methods for the calculation of phase equilibria are presented.

  10. Pregnant teenagers' group: contributions to prenatal care.

    Science.gov (United States)

    Queiroz, Maria Veraci Oliveira; Menezes, Giselle Maria Duarte; Silva, Thaís Jormanna Pereira; Brasil, Eysler Gonçalves Maia; Silva, Raimunda Magalhães da

    2017-06-05

    To describe changes in nurses' care following the implementation of a group of pregnant teenagers in prenatal care based on the expectations and experiences of pregnant teenagers. Qualitative and descriptive study conducted from February to November 2013 at a Primary Care Unit in Fortaleza, Ceará, Brazil, through focus groups with 16 adolescents from the group of pregnant women in the second or third trimester of pregnancy. The analysis identified central ideas and units of meanings that formed the categories. The strategy of a group of pregnant teenagers, which provides a space for coexistence and the establishment of ties encourages these individuals to talk about their needs, re-signifying their ties. Educational strategies to promote self-care of pregnant teenagers and care for their babies involve the sharing of experiences, doubts and beliefs. Considerations and suggestions of the adolescents contributed to guide nurses' practice and provide a strategic space of care and support for pregnant adolescents in primary care.

  11. Protamine titration.

    Science.gov (United States)

    Newall, Fiona

    2013-01-01

    Protamine titration is the gold standard method for the measurement of unfractionated heparin (UFH) concentration in plasma. Protamine titration produces reliable and reproducible results; however it is -generally not considered a convenient assay for current clinical management of UFH as it is not readily automated (Olson et al. Arch Pathol Lab Med 122(9):782-798, 1998). Early clinical trials of UFH therapy determined that a heparin concentration of 0.2-0.4 U/ml by protamine titration correlated to an APTT of 1.5-2.5 times higher compared to baseline values produced desirable UFH safety and efficacy outcomes (Hull et al. N Engl J Med 315(18):1109-1114, 1986; Hull et al. N Engl J Med 322:1260-1264, 1990; Turpie et al. N Engl J Med 320:352-357, 1989; Brill-Edwards et al. Ann Intern Med 119(2):104-109, 1993; Hull Int Angiol 14(1):32-34, 1995). Such studies paved the way to the current view that it is no longer ideal to manage UFH based solely upon a 1.5-2.5 times prolongation of the "normal" APTT. Most advisory bodies recommend therapeutic APTTs be determined by correlating APTT results with therapeutic UFH levels as measured by anti-Xa assay (0.35-0.7 U/ml) or protamine titration (0.2-0.4 U/ml) (Hirsh and Raschke. Chest 126(3):188S-203S, 2004) (see Note 1). The concentration of UFH in a sample is measured by determining the amount of protamine required to return the thrombin clotting time (TCT) test (prolonged by UFH) to a pre-UFH level (Laffan and Manning. Dacie and Lewis: practical haematology. Churchill Livingstone: London, 2001).

  12. ''Titration'' polymerization of monovinylacetylene

    NARCIS (Netherlands)

    Mavinkurve, A; Visser, S; vandenBroek, W; Pennings, AJ

    1996-01-01

    A polymer consisting of a saturated carbon backbone with pendent acetylenic groups was prepared from monovinylacetylene. A titration was performed between the monomer and tertiary butyllithium, its lithiating agent. The charge transfer complex formed between the solvent THF and the tertiary butyllit

  13. 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.

    Science.gov (United States)

    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.

  14. Computer Aided Flowsheet Design using Group Contribution Methods

    DEFF Research Database (Denmark)

    Bommareddy, Susilpa; Eden, Mario R.; Gani, Rafiqul

    In this paper, a systematic group contribution based framework is presented for synthesis of process flowsheets from a given set of input and output specifications. Analogous to the group contribution methods developed for molecular design, the framework employs process groups to represent...

  15. Computer Aided Flowsheet Design using Group Contribution Methods

    DEFF Research Database (Denmark)

    Bommareddy, Susilpa; Eden, Mario R.; Gani, Rafiqul

    2011-01-01

    In this paper, a systematic group contribution based framework is presented for synthesis of process flowsheets from a given set of input and output specifications. Analogous to the group contribution methods developed for molecular design, the framework employs process groups to represent...

  16. Group Contribution Based Process Flowsheet Synthesis, Design and Modelling

    DEFF Research Database (Denmark)

    d'Anterroches, Loïc; Gani, Rafiqul

    2005-01-01

    In a group contribution method for pure component property prediction, a molecule is described as a set of groups linked together to form a molecular structure. In the same way, for flowsheet "property" prediction, a flowsheet can be described as a set of process-groups linked together to represent...... provides a contribution to the "property" of the flowsheet, which can be performance in terms of energy consumption, thereby allowing a flowsheet "property" to be calculated, once it is described by the groups. Another feature of this approach is that the process-group attachments provide automatically...... the flowsheet structure. Just as a functional group is a collection of atoms, a process-group is a collection of operations forming an "unit" operation or a set of "unit" operations. The link between the process-groups are the streams similar to the bonds that are attachments to atoms/groups. Each process-group...

  17. Group Contribution Based Process Flowsheet Synthesis, Design and Modelling

    DEFF Research Database (Denmark)

    Gani, Rafiqul; d'Anterroches, Loïc

    2004-01-01

    This paper presents a process-group-contribution Method to model. simulate and synthesize a flowsheet. The process-group based representation of a flowsheet together with a process "property" model are presented. The process-group based synthesis method is developed on the basis of the computer...

  18. Peer-Assessing Peers' Contribution to EFL Group Presentations

    Science.gov (United States)

    Saito, Hidetoshi; Fujita, Tomoko

    2009-01-01

    The aim of this study is three-fold: (1) to examine the similarities and differences between instructor and peer assessments of EFL group presentations; (2) to understand the utility of peer assessment for discriminating each group member's contribution to group presentations in college EFL classrooms; and (3) to investigate the relationship…

  19. A Group Contribution Method for Estimating Cetane and Octane Numbers

    Energy Technology Data Exchange (ETDEWEB)

    Kubic, William Louis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Process Modeling and Analysis Group

    2016-07-28

    Much of the research on advanced biofuels is devoted to the study of novel chemical pathways for converting nonfood biomass into liquid fuels that can be blended with existing transportation fuels. Many compounds under consideration are not found in the existing fuel supplies. Often, the physical properties needed to assess the viability of a potential biofuel are not available. The only reliable information available may be the molecular structure. Group contribution methods for estimating physical properties from molecular structure have been used for more than 60 years. The most common application is estimation of thermodynamic properties. More recently, group contribution methods have been developed for estimating rate dependent properties including cetane and octane numbers. Often, published group contribution methods are limited in terms of types of function groups and range of applicability. In this study, a new, broadly-applicable group contribution method based on an artificial neural network was developed to estimate cetane number research octane number, and motor octane numbers of hydrocarbons and oxygenated hydrocarbons. The new method is more accurate over a greater range molecular weights and structural complexity than existing group contribution methods for estimating cetane and octane numbers.

  20. Computer Aided Flowsheet Design using Group Contribution Methods

    DEFF Research Database (Denmark)

    Bommareddy, Susilpa; Eden, Mario R.; Gani, Rafiqul

    In this paper, a systematic group contribution based framework is presented for synthesis of process flowsheets from a given set of input and output specifications. Analogous to the group contribution methods developed for molecular design, the framework employs process groups to represent...... information of each flowsheet to minimize the computational load and information storage. The design variables for the selected flowsheet(s) are identified through a reverse simulation approach and are used as initial estimates for rigorous simulation to verify the feasibility and performance of the design....

  1. Prediction of biodegradation kinetics using a nonlinear group contribution method

    Energy Technology Data Exchange (ETDEWEB)

    Tabak, H.H. (Environmental Protection Agency, Cincinnati, OH (United States)); Govind, R. (Univ. of Cincinnati, OH (United States))

    1993-02-01

    The fate of organic chemicals in the environment depends on their susceptibility to biodegradation. Hence, development of regulations concerning their manufacture and use requires information on the extent and rate of biodegradation. Recent studies have attempted to correlate the kinetics of biodegradation with the molecular structure of the compound. This has led to the development of structure-biodegradation relationships (SBRs) using the group contribution approach. Each defined group present in the chemical structure of the compound is assigned a unique numerical contribution toward the calculation of the biodegradation kinetic constants. In this paper, a nonlinear group contribution method has been developed using neural networks; it is trained using literature data on the first-order biodegradation kinetic rate constant for a number of priority pollutants. The trained neural network is then used to predict the biodegradation kinetic constant for a new list of compounds, and results have been compared with the experimental values and the predictions obtained from a linear group contribution method. It has been shown that the nonlinear group contribution method using neural networks is able to provide a superior fit to the training set data and test data set and produce a lower prediction error than the previous linear method.

  2. Global Manufacturing Research: Experience Exchange Group (EEG) contributions

    DEFF Research Database (Denmark)

    Bruun, Peter

    1998-01-01

    The intention of this paper is to clarify if and how an ExperienceExchange Group (EEG) can be involved in a research process in the areaof industrial management. For exemplification of the topic an ongoingresearch in global manufacturing is referred to. In this research itwas after a series...... activities aredescribed and a tentative coupling to the phases in a research processis proposed. Following this is a discussion of methodological andquality requirements. It is considered how EEG activities couldpossible contribute to an industrial rooted research. The paper endsup looking at future research...

  3. Filtrates & Residues: Olfactory Titration.

    Science.gov (United States)

    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)

  4. Treating student contributions as displays of understanding in group supervision

    DEFF Research Database (Denmark)

    2012-01-01

    The analyses this paper reports come from ongoing research into the interactive establishment of local social order in an educational setting (Day & Kjærbeck 2008, Day & Kjærbeck, in preparation). In focus for this paper are a particular sort of activity in the setting, 'group supervision', whereby...... students working in 'project groups' are to meet with their 'supervisor' to discuss the group's ongoing project, and a particular set of interactive phenomena, namely students' displays of comprehension directed toward the supervisor following his or evaluation of their work. This work is in line...

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

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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…

  7. Extended Group Contribution Model for Polyfunctional Phase Equilibria

    DEFF Research Database (Denmark)

    Abildskov, Jens

    -liquid equilibria from data on binary mixtures, composed of structurally simple molecules with a single functional group. More complex is the situation with mixtures composed of structurally more complicated molecules or molecules with more than one functional group. The UNIFAC method is extended to handle...... polyfunctional group situations, based on additional information on molecular structure. The extension involves the addition of second-order correction terms to the existing equation. In this way the current first-order formulation is retained. The second-order concept is developed for mixture properties based....... In chapter 4 parameters are estimated for the first-order UNIFAC model, based on which parameters are estimated for one of the second-order models described in chapter 3. The parameter estimation is based on measured binary data on around 4000 systems, covering 11 C-, H- and O-containing functional groups...

  8. Contribution to CCN Workshop report from University of Wyoming group

    Science.gov (United States)

    Rogers, D. C.; Politovich, M. K.

    1981-01-01

    The group's CCN counter is described. It is a static, horizontal, parallel plate thermal gradient diffusion chamber. Examples of the application of the CCN are presented and include the CCN spectra measured during the winter of 1978-79 near Elk Mountain, Wyoming. Comparisons of droplet concentrations derived from upwind CCN spectra are covered.

  9. 对用于活性炭表面含氧官能团分析的Boehm滴定法的几点讨论%Discussion on the Boehm titration method used in analysis of surface oxygen functional groups on activated carbon

    Institute of Scientific and Technical Information of China (English)

    毛磊; 童仕唐; 王宇

    2011-01-01

    不同的研究者在采用Boehm滴定法测定活性炭表面含氧官能团的含量时在操作方法上存在差异.本文探讨了Boehm滴定法中CO2的去除,直接滴定与返滴定,振荡时间,溶液的浓度对滴定过程的影响,提出适宜的操作建议.%Boehm titration has been carried out in different ways by different researchers to analyze the surface oxygen functional groups.The methods of CO2 expulsion, direct titration and back titration, duration of shaking and concentration of titrant are discussed.The suitable operation suggestions are proposed.

  10. Group contribution modelling for the prediction of safety-related and environmental properties

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    We present a new set of property prediction models based on group contributions to predict major safety-related and environmental properties for organic compounds. The predicted list of properties includes lower and upper flammability limits, heat of combustion, auto ignition temperature, global...... models like group contribution (GC) models can estimate data. However, the estimation needs to be accurate, reliable and as little time-consuming as possible so that the models can be used on the fly. In this study the Marrero and Gani group contribution (MR GC) method has been used to develop the models...... for safety-related and environmental properties. The method considers the group contribution in three levels: The contributions from a specific functional group (1st order parameters), from poly-functional (2nd order parameters) as well as from structural groups (3rd order parameters). The latter two classes...

  11. The pernicious effects of unstable work group membership : How work group changes undermine unique task contributions and newcomer acceptance

    NARCIS (Netherlands)

    Rink, Floor; Ellemers, Naomi

    2015-01-01

    This research demonstrates that group membership instability tends to raise self-related concerns that make it less likely that people value and accept constructive task contributions offered by newcomers. In Study 1 (N = 88), unstable group membership heightened self-related concerns. Participants

  12. Treatment discontinuation and tolerability as a function of dose and titration of duloxetine in the treatment of major depressive disorder

    Directory of Open Access Journals (Sweden)

    Harada E

    2016-01-01

    Full Text Available Eiji Harada,1 Osamu Shirakawa,2 Yoichi Satoi,3 Lauren B Marangell,4 Rodrigo Escobar5 1Eli Lilly Japan K.K., Medicines Development Unit Japan, Medical Science, Kobe, 2Department of Neuropsychiatry, Kinki University Faculty of Medicine, Osakasayama, 3Eli Lilly Japan K.K., Medicines Development Unit Japan, Statistical Science, Kobe, Japan; 4The University of Texas Health Science Center School of Medicine, Houston, TX, 5Eli Lilly and Company, Neuroscience, Indianapolis, IN, USA Purpose: We sought to better understand how dose and titration with duloxetine treatment may impact tolerability and treatment discontinuation in patients with major depressive disorder.Patients and methods: 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.Results: 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.Conclusion: 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. Keywords: antidepressant, dose, duloxetine, major depressive disorder, titration

  13. Prediction of heat capacities and heats of vaporization of organic liquids by group contribution methods

    DEFF Research Database (Denmark)

    Ceriani, Roberta; Gani, Rafiqul; Meirelles, A.J.A.

    2009-01-01

    In the present work a group contribution method is proposed for the estimation of the heat capacity of organic liquids as a function of temperature for fatty compounds found in edible oil and biofuels industries. The data bank used for regression of the group contribution parameters (1395 values...

  14. A predictive group-contribution simplified PC-SAFT equation of state: Application to polymer systems

    DEFF Research Database (Denmark)

    Tihic, Amra; Kontogeorgis, Georgios; von Solms, Nicolas

    2008-01-01

    A group-contribution (GC) method is coupled with the molecular-based perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) to predict its characteristic pure compound parameters. The estimation of group contributions for the parameters is based on a parameter...... are the molecular structure of the polymer of interest in terms of functional groups and a single binary interaction parameter for accurate mixture calculations....

  15. Estimation and Uncertainty Analysis of Flammability Properties of Chemicals using Group-Contribution Property Models

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    or time constraints, property prediction models like group contribution (GC) models can estimate flammability data. The estimation needs to be accurate, reliable and as less time consuming as possible. However, GC property prediction methods frequently lack rigorous uncertainty analysis. Hence......, there is no information about the reliability of the data. Furthermore, the global optimality of the GC parameters estimation is often not ensured. In this research project flammability-related property data, like LFL and UFL, are estimated using the Marrero and Gani group contribution method (MG method). In addition...... the group contribution in three levels: The contributions from a specific functional group (1st order parameters), from polyfunctional (2nd order parameters) as well as from structural groups (3rd order parameters). The latter two classes of GC factors provide additional structural information beside...

  16. Contribution of Food Groups to Energy and Nutrient Intakes in Five Developed Countries

    Directory of Open Access Journals (Sweden)

    Nancy Auestad

    2015-06-01

    Full Text Available Economic growth in developing countries and globalization of the food sector is leading to increasingly similar food consumption patterns worldwide. The aim of this study was to describe similarities and differences in the contributions of main food groups to energy and nutrient intakes in five developed countries across three continents. We obtained summary reports of national food consumption survey data from Australia, France, Denmark, the Netherlands, and the United States. Survey years spanned 2003–2012; sample size ranged from 1444 to 17,386. To mitigate heterogeneity of food groups across countries, we recategorized each survey’s reported food groups and subgroups into eight main food groups and, for three countries, a ninth “mixed dishes” group. We determined the percent contribution of each food group to mean daily intakes of energy, saturated fat, sodium, fiber, and ten vitamins and minerals that are commonly under-consumed. Differences in findings from surveys utilizing a foods-as-consumed versus a disaggregated or ingredients approach to food group composition and contributions from the milk and milk products group, a source of several under-consumed nutrients, were explored. Patterns of food group contributions to energy and nutrient intakes were generally similar across countries. Some differences were attributable to the analytical approach used by the surveys. For the meat/protein, milk and milk products, vegetables, and fruit groups, percent contributions to key nutrient intakes exceeded percent contributions to energy intake. The mixed dishes group provided 10%–20% of total daily energy and a similar 10%–25% of the daily intake of several nutrients. This descriptive study contributes to an understanding of food group consumption patterns in developed countries.

  17. Contribution of Food Groups to Energy and Nutrient Intakes in Five Developed Countries.

    Science.gov (United States)

    Auestad, Nancy; Hurley, Judith S; Fulgoni, Victor L; Schweitzer, Cindy M

    2015-06-08

    Economic growth in developing countries and globalization of the food sector is leading to increasingly similar food consumption patterns worldwide. The aim of this study was to describe similarities and differences in the contributions of main food groups to energy and nutrient intakes in five developed countries across three continents. We obtained summary reports of national food consumption survey data from Australia, France, Denmark, the Netherlands, and the United States. Survey years spanned 2003-2012; sample size ranged from 1444 to 17,386. To mitigate heterogeneity of food groups across countries, we recategorized each survey's reported food groups and subgroups into eight main food groups and, for three countries, a ninth "mixed dishes" group. We determined the percent contribution of each food group to mean daily intakes of energy, saturated fat, sodium, fiber, and ten vitamins and minerals that are commonly under-consumed. Differences in findings from surveys utilizing a foods-as-consumed versus a disaggregated or ingredients approach to food group composition and contributions from the milk and milk products group, a source of several under-consumed nutrients, were explored. Patterns of food group contributions to energy and nutrient intakes were generally similar across countries. Some differences were attributable to the analytical approach used by the surveys. For the meat/protein, milk and milk products, vegetables, and fruit groups, percent contributions to key nutrient intakes exceeded percent contributions to energy intake. The mixed dishes group provided 10%-20% of total daily energy and a similar 10%-25% of the daily intake of several nutrients. This descriptive study contributes to an understanding of food group consumption patterns in developed countries.

  18. Flowing toward Correct Contributions during Group Problem Solving: A Statistical Discourse Analysis

    Science.gov (United States)

    Chiu, Ming Ming

    2008-01-01

    Groups that created more correct ideas (correct contributions or CCs) might be more likely to solve a problem, and students' recent actions (micro-time context) might aid CC creation. 80 high school students worked in groups of 4 on an algebra problem. Groups with higher mathematics grades or more CCs were more likely to solve the problem. Dynamic…

  19. Contribution of the trifluoroacetyl group in the thermodynamics of antigen-antibody binding.

    Science.gov (United States)

    Oda, Masayuki; Saito, Minoru; Tsumuraya, Takeshi; Fujii, Ikuo

    2010-01-01

    We analyzed the binding of the 7C8 antibody to the chloramphenicol phosphonate antigens-one containing a trifluoroacetyl group (CP-F) and the other containing an acetyl group (CP-H)-by using isothermal titration calorimetry (ITC). The thermodynamic difference due to the substitution of F by H was evaluated using free energy calculations based on molecular dynamics (MD) simulations. We have previously shown that another antibody, namely, 6D9, binds more weakly to CP-H than to CP-F, mainly due to the different hydration free energies of the dissociated state and not due to the unfavorable hydrophobic interactions with the antibody in the bound state. Unlike in the binding of the trifluoroacetyl group with 6D9, in its binding with 7C8, it is exposed to the solvent, as seen in the crystal structure of the complex of 7C8 with CP-F. The thermodynamic analysis performed in this study showed that the binding affinity of 7C8 for CP-H is similar to that for CP-F, but this binding to CP-H is accompanied with less favorable enthalpy and more favorable entropy changes. The free energy calculations indicated that, upon the substitution of F by H, enthalpy and entropy changes in the associated and dissociated states were decreased, but the magnitude of enthalpy and entropy changes in the dissociated state was larger than that in the associated state. The differences in binding free energy, enthalpy, and entropy changes determined by the free energy calculations for the substitution of F by H are in good agreement with the experimental results.

  20. Estimating the contribution of genetic variants to difference in incidence of disease between population groups.

    Science.gov (United States)

    Moonesinghe, Ramal; Ioannidis, John P A; Flanders, W Dana; Yang, Quanhe; Truman, Benedict I; Khoury, Muin J

    2012-08-01

    Genome-wide association studies have identified multiple genetic susceptibility variants to several complex human diseases. However, risk-genotype frequency at loci showing robust associations might differ substantially among different populations. In this paper, we present methods to assess the contribution of genetic variants to the difference in the incidence of disease between different population groups for different scenarios. We derive expressions for the contribution of a single genetic variant, multiple genetic variants, and the contribution of the joint effect of a genetic variant and an environmental factor to the difference in the incidence of disease. The contribution of genetic variants to the difference in incidence increases with increasing difference in risk-genotype frequency, but declines with increasing difference in incidence between the two populations. The contribution of genetic variants also increases with increasing relative risk and the contribution of joint effect of genetic and environmental factors increases with increasing relative risk of the gene-environmental interaction. The contribution of genetic variants to the difference in incidence between two populations can be expressed as a function of the population attributable risks of the genetic variants in the two populations. The contribution of a group of genetic variants to the disparity in incidence of disease could change considerably by adding one more genetic variant to the group. Any estimate of genetic contribution to the disparity in incidence of disease between two populations at this stage seems to be an elusive goal.

  1. Isothermal titration calorimetry and differential scanning calorimetry.

    Science.gov (United States)

    Holdgate, Geoff

    2009-01-01

    Isothermal titration [Holdgate (BioTechniques 31:164-184, 2001); Ward and Holdgate (Prog. Med. Chem. 38:309-376, 2001); O'Brien et al. (2001) Isothermal titration calorimetry of biomolecules. In: Harding, S. E. and Chowdhry, B. Z. (eds.), Protein-Ligand Interactions: Hydrodynamics and Calorimetry, A Practical Approach. Oxford University Press, Oxford, UK] and differential scanning calorimetry [Jelesarov and Bosshard (J. Mol. Recognit. 12:3-18, 1999); Privalov and Dragan (Biophys. Chem. 126:16-24, 2007); Cooper et al. (2001) Differential scanning microcalorimetry. In: Harding, S. E. and Chowdhry, B. Z. (eds.), Protein-Ligand Interactions: Hydrodynamics and Calorimetry, A Practical Approach. Oxford University Press, Oxford, UK] are valuable tools for characterising protein targets, and their interactions with ligands, during the drug discovery process. The parameters obtained from these techniques: triangle DeltaH, triangle DeltaG, triangle DeltaS, and triangle DeltaC (p), are properties of the entire system studied and may be composed of many contributions, including the binding reaction itself, conformational changes of the protein and/or ligand during complexation, changes in solvent organisation or other equilibria linked to the binding process. Dissecting and understanding these components, and how they contribute to binding interactions, is a critical step in the ability to design ligands that have high binding affinity for the target protein.

  2. Her earnings: Exploring variation in wives' earning contributions across six major Asian groups and Whites.

    Science.gov (United States)

    Kulkarni, Veena S

    2015-07-01

    Previous research on understanding race-ethnic differentials in employment and economic contributions by married women has primarily focused on Blacks, Hispanics, or Whites. This study investigates variations in wives' earning contributions as measured by wives earnings as a proportion of total annual household earnings among six Asian groups, Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese relative to native born non-Hispanic White. I disaggregate the six Asian groups by their ethnicity and nativity status. Using pooled data from 2009-2011 American Community Survey, the findings show significance of human capital, hours of paid labor market engagement and nativity status. There is strong and negative association between husbands' human capital and labor supply with wives' earning contributions suggesting near universality of male-breadwinner status. Notwithstanding the commonalities, there is significant intergroup diversity. While foreign born and native born Filipina wives despite their spouses' reasonably high human capital and work hours, contribute one of the highest shares, the same cannot be said for the Asian Indians and Japanese. For foreign born Asian Indian and to some extent Japanese women, their high human capital is not translated to high earning contribution after controlling for husband's human capital. Further, nativity status impacts groups differentially. Native born Vietnamese wives contribute the greatest. Overall, the findings underscore the relevance of employing multiple conceptual frameworks in understanding earning contributions of foreign and native born Asian wives belonging to the six Asian groups, Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Contribution of the heme propionate groups to the electron transfer and electrostatic properties of myoglobin.

    Science.gov (United States)

    Lim, Anthony R; Sishta, Bhavini P; Mauk, A Grant

    2006-12-01

    The role of the heme propionate groups in determining the electron transfer and electrostatic properties of myoglobin have been studied by thermodynamic, kinetic, and spectroscopic studies of horse heart myoglobin in which the heme propionate groups are esterified. Spectroelectrochemical analysis has established that the E(m,7) of dimethylester heme-substituted Mb (DME-Mb) (E(m,7)=100.2(2)mV vs. NHE (Normal Hydrogen Electrode) (25 degrees C) is increased approximately 40mV relative to that of the native protein with DeltaH degrees =-12.9(2) kcal/mol and DeltaS degrees =-51.0(8) cal/mol/deg (pH 7.0, mu=0.1M (phosphate)). The second order rate constant for reduction of DME-metMb by Fe(EDTA)(2-) is increased >400-fold relative to that for reduction of native metMb to a value of 1.34(2)x10(3)M(-1)s(-1) with DeltaS(double dagger)=-13(1) cal/mol/deg and DeltaH(double dagger)=9.2(3) (pH 7.0, micro=0.1M (phosphate)). Analysis of the pH dependences of the reduction potential and rate constant for reduction by Fe(EDTA)(2-) demonstrates that heme propionate esterification introduces significant changes into the electrostatic interactions in myoglobin. These changes are also manifested by differences in the pH dependences of the (1)H NMR spectra of native and DME-metMb that reveal shifts in pK(a) values for specific His residues as the result of heme propionate esterification. In sum, the current results establish that heme propionate esterification not only affects the electron transfer properties of myoglobin but also influences the titration behavior of specific His residues.

  4. Factors Contributing to Student Engagement in an Instructional Facebook Group for Undergraduate Mathematics

    Science.gov (United States)

    Gregory, Peter L.; Gregory, Karen M.; Eddy, Erik R.

    2016-01-01

    This study investigates factors contributing to student engagement in an educational Facebook group. The study is based on survey results of 138 undergraduate mathematics students at a highly diverse urban public university. Survey measures included engagement in the Facebook group, access to Facebook, comfort using technology, and interest in the…

  5. A NEW METHOD FOR QUANTIFYING THE DEGREE OF SUBSTITUTION OF AMPHOTERIC STARCH WITH CARBOXYLIC GROUP AND QUATERNARY AMMONIUM GROUP IN PAPERMAKING:NEW COLLOID TITRATION METHOD%造纸用季铵盐羧酸型两性淀粉的阴、阳离子取代度的新测量方法:新胶体滴定法

    Institute of Scientific and Technical Information of China (English)

    罗明辉; 陆恩锡

    2008-01-01

    A new colloid titration method for analyzing the degree of substitute (DS) of amphoteric starch with carboxylic and quaternary ammonium groups is first developed in this work. The cationic or anionic desires will be measured while measuring the oxidized starches of known carboxylic DS or cationic starches of known cationic DS by back titration. The amphoteric starch′s DS will be reached by interpolation method while two calibration equations of the DSes and desires are obtained through the polynomial regression based on the analyzed data. The cationic and anionic DS in the traditional method are 0.032 and 0.022, respectively. Their DS in the New Colloid Titration are 0.033 and 0.018, respectively. In comparison with the traditional method, the new method avoids the variations of the cationic and anionic groups during the analyzing. Thus, when the starch′s complex mechanism is analyzed, the results obtained by the new method are more accurate and reflect the real degree of substitution of the amphoteric starch.%首次提出了用胶体滴定法测量季铵盐羧酸型两性淀粉的阴、阳离子取代度.通过测量已知羧基取代度的氧化淀粉或已知季铵盐取代度的阳离子淀粉的阳性需求量或阴性需求量,对其做出取代度与需求量的校正工作方程,使用内插法分别得出了该两性淀粉的阳离子取代度和阴离子取代度.在用传统测量方法测量该两性淀粉的阴、阳离子取代度分别为0.022和0.032的情况下,使用新胶体滴定法测量的结果分别为0.018和0.033.对比两种方法,使用新胶体滴定法避免了阴、阳离子基团在测量过程中的变化.通过机理分析,使用胶体滴定法测量该淀粉更准确、更符合实际情况.

  6. Toward understanding and treating violence in America: some contributions from group dynamic and group therapy perspectives: introduction to part I.

    Science.gov (United States)

    Klein, Robert H; Schermer, Victor L

    2015-01-01

    The co-editors introduce a two-part Special Section of the Journal devoted to understanding and treating violence in America. They examine the relevance of clinical experience for contributions that can be made by group therapists and group dynamic thinkers to the growing national dialogue about this problem. The pervasive nature, causes, and different forms of violence in the United States are compared with those found in other countries. Underlying sociocultural values and myths, historical and current cultural contexts are considered breeding grounds for potential violence. How therapists can promote healthy change in their groups and in the broader society is explored. The articles contained in part one are reviewed against this backdrop.

  7. Process synthesis, design and analysis using a process-group contribution method

    DEFF Research Database (Denmark)

    Kumar Tula, Anjan; Eden, Mario R.; Gani, Rafiqul

    2015-01-01

    This paper describes the development and application of a process-group contribution method to model, simulate and synthesize chemical processes. Process flowsheets are generated in the same way as atoms or groups of atoms are combined to form molecules in computer aided molecular design (CAMD......) techniques. The fundamental pillars of this framework are the definition and use of functional process-groups (building blocks) representing a wide range of process operations, flowsheet connectivity rules to join the process-groups to generate all the feasible flowsheet alternatives and flowsheet property...

  8. Isothermal titration calorimetric analysis of the interaction between cationic lipids and plasmid DNA.

    Science.gov (United States)

    Lobo, B A; Davis, A; Koe, G; Smith, J G; Middaugh, C R

    2001-02-01

    The effects of buffer and ionic strength upon the enthalpy of binding between plasmid DNA and a variety of cationic lipids used to enhance cellular transfection were studied using isothermal titration calorimetry at 25.0 degrees C and pH 7.4. The cationic lipids DOTAP (1,2-dioleoyl-3-trimethyl ammonium propane), DDAB (dimethyl dioctadecyl ammonium bromide), DOTAP:cholesterol (1:1), and DDAB:cholesterol (1:1) bound endothermally to plasmid DNA with a negligible proton exchange with buffer. In contrast, DOTAP: DOPE (L-alpha-dioleoyl phosphatidyl ethanolamine) (1:1) and DDAB:DOPE (1:1) liposomes displayed a negative enthalpy and a significant uptake of protons upon binding to plasmid DNA at neutral pH. These findings are most easily explained by a change in the apparent pKa of the amino group of DOPE upon binding. Complexes formed by reverse addition methods (DNA into lipid) produced different thermograms, sizes, zeta potentials, and aggregation behavior, suggesting that structurally different complexes were formed in each titration direction. Titrations performed in both directions in the presence of increasing ionic strength revealed a progressive decrease in the heat of binding and an increase in the lipid to DNA charge ratio at which aggregation occurred. The unfavorable binding enthalpy for the cationic lipids alone and with cholesterol implies an entropy-driven interaction, while the negative enthalpies observed with DOPE-containing lipid mixtures suggest an additional contribution from changes in protonation of DOPE.

  9. Promoting Perceived Benefits of Group Projects: The Role of Instructor Contributions and Intragroup Processes

    Science.gov (United States)

    Bailey, Sarah; Barber, Larissa K.; Ferguson, Amanda J.

    2015-01-01

    Group projects are often used in psychology courses to prepare students for future collaborative work. However, psychology alumni report that their education did not adequately prepare them for collaborative work. To better understand these perceptions, this study examined how instructor contributions (involvement and evaluation techniques)…

  10. Outlier treatment for improving parameter estimation of group contribution based models for upper flammability limit

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    2015-01-01

    Flammability data is needed to assess the risk of fire and explosions. This study presents a new group contribution (GC) model to predict the upper flammability limit UFL oforganic chemicals. Furthermore, it provides a systematic method for outlier treatment inorder to improve the parameter...

  11. Promoting Perceived Benefits of Group Projects: The Role of Instructor Contributions and Intragroup Processes

    Science.gov (United States)

    Bailey, Sarah; Barber, Larissa K.; Ferguson, Amanda J.

    2015-01-01

    Group projects are often used in psychology courses to prepare students for future collaborative work. However, psychology alumni report that their education did not adequately prepare them for collaborative work. To better understand these perceptions, this study examined how instructor contributions (involvement and evaluation techniques)…

  12. The Contribution of Group Work Programmes to Early Intervention and Improving Children's Emotional Well-Being

    Science.gov (United States)

    Parton, Christine; Manby, Martin

    2009-01-01

    Recent government policy has emphasised links between the acquisition of social skills by children and young people and their educational attainment. This study aims to fill a gap in the literature about the contribution of school-based group work programmes to developing children's social skills. National Society for the Prevention of Cruelty to…

  13. Group-Contribution based Property Estimation and Uncertainty analysis for Flammability-related Properties

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Marcarie, Camille; Abildskov, Jens

    2016-01-01

    This study presents new group contribution (GC) models for the prediction of Lower and Upper Flammability Limits (LFL and UFL), Flash Point (FP) and Auto Ignition Temperature (AIT) of organic chemicals applying the Marrero/Gani (MG) method. Advanced methods for parameter estimation using robust...

  14. An adaptive distance-based group contribution method for thermodynamic property prediction.

    Science.gov (United States)

    He, Tanjin; Li, Shuang; Chi, Yawei; Zhang, Hong-Bo; Wang, Zhi; Yang, Bin; He, Xin; You, Xiaoqing

    2016-09-14

    In the search for an accurate yet inexpensive method to predict thermodynamic properties of large hydrocarbon molecules, we have developed an automatic and adaptive distance-based group contribution (DBGC) method. The method characterizes the group interaction within a molecule with an exponential decay function of the group-to-group distance, defined as the number of bonds between the groups. A database containing the molecular bonding information and the standard enthalpy of formation (Hf,298K) for alkanes, alkenes, and their radicals at the M06-2X/def2-TZVP//B3LYP/6-31G(d) level of theory was constructed. Multiple linear regression (MLR) and artificial neural network (ANN) fitting were used to obtain the contributions from individual groups and group interactions for further predictions. Compared with the conventional group additivity (GA) method, the DBGC method predicts Hf,298K for alkanes more accurately using the same training sets. Particularly for some highly branched large hydrocarbons, the discrepancy with the literature data is smaller for the DBGC method than the conventional GA method. When extended to other molecular classes, including alkenes and radicals, the overall accuracy level of this new method is still satisfactory.

  15. Competition over personal resources favors contribution to shared resources in human groups

    DEFF Research Database (Denmark)

    Barker, Jessie; Barclay, Pat; Reeve, H. Kern

    2013-01-01

    laboratory economic games with humans, comparing people's investment decisions in games with and without the options to compete over personal resources or invest in a group resource. Our results help explain why people cooperatively contribute to group resources, suggest how a tragedy of the commons may......Members of social groups face a trade-off between investing selfish effort for themselves and investing cooperative effort to produce a shared group resource. Many group resources are shared equitably: they may be intrinsically non-excludable public goods, such as vigilance against predators, or so...... large that there is little cost to sharing, such as cooperatively hunted big game. However, group members' personal resources, such as food hunted individually, may be monopolizable. In such cases, an individual may benefit by investing effort in taking others' personal resources, and in defending one...

  16. Ionic conductivities of solid polymer electrolyte/salt systems: Group-contribution method

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Jae Ho; Bae, Young Chan [Division of Chemical Engineering and Molecular Thermodynamics Laboratory, Hanyang University, Seoul 133791 (Korea, Republic of)

    2006-06-19

    We establish a new group-contribution model based on the Nernst-Einstein equation in which the diffusion coefficient is derived from the modified double-lattice (MDL) model and the Debye-Huckel (DH) theory. The model includes the combinatorial energy contribution that is responsible for the revised Flory-Huggins entropy of mixing, the van der Waals energy contribution from dispersion, and the polar force and the specific energy contribution from hydrogen bonding. The Nernst-Einstein equation takes into account the mobility of the salt and the motion of the polymer host. To describe the segmental motion of the polymer chain, which is the well known conduction mechanism for solid polymer electrolyte (SPE) systems, the effective co-ordinated unit parameter is introduced. Our results show that good agreement is obtained upon comparison with experimental data of various PEO and salt systems in the interested ranges. (author)

  17. A new group contribution-based model for estimation of lower flammability limit of pure compounds.

    Science.gov (United States)

    Gharagheizi, Farhad

    2009-10-30

    In the present study, a new method is presented for estimation of lower flammability limit (LFL) of pure compounds. This method is based on a combination of a group contribution method and neural networks. The parameters of the model are the occurrences of a new collection of 105 functional groups. Basing on these 105 functional groups, a feed forward neural network is presented to estimate the LFL of pure compounds. The average absolute deviation error obtained over 1057 pure compounds is 4.62%. Therefore, the model is an accurate model and can be used to predict the LFL of a wide range of pure compounds.

  18. Estimation of Physical Properties of Amino Acids by Group-Contribution Method

    DEFF Research Database (Denmark)

    Jhamb, Spardha Virendra; Liang, Xiaodong; Gani, Rafiqul

    2017-01-01

    In this paper, we present group-contribution (GC) based property models for estimation of physical properties of amino acids using their molecular structural information. The physical properties modelled in this work are normal melting point (Tm), aqueous solubility (Ws), and octanol....../water partition coefficient (Kow) of amino acids. The developed GC-models are based on the published GC-method by Marrero and Gani (J. Marrero, R. Gani, Fluid Phase Equilib. 2001, 183-184, 183-208) with inclusion of new structural parameters (groups and molecular weight of compounds). The main objective...... of introducing these new structural parameters in the GC-model is to provide additional structural information for amino acids having large and complex structures and thereby improve predictions of physical properties of amino acids. The group-contribution values were calculated by regression analysis using...

  19. Competition over personal resources favors contribution to shared resources in human groups.

    Directory of Open Access Journals (Sweden)

    Jessica L Barker

    Full Text Available Members of social groups face a trade-off between investing selfish effort for themselves and investing cooperative effort to produce a shared group resource. Many group resources are shared equitably: they may be intrinsically non-excludable public goods, such as vigilance against predators, or so large that there is little cost to sharing, such as cooperatively hunted big game. However, group members' personal resources, such as food hunted individually, may be monopolizable. In such cases, an individual may benefit by investing effort in taking others' personal resources, and in defending one's own resources against others. We use a game theoretic "tug-of-war" model to predict that when such competition over personal resources is possible, players will contribute more towards a group resource, and also obtain higher payoffs from doing so. We test and find support for these predictions in two laboratory economic games with humans, comparing people's investment decisions in games with and without the options to compete over personal resources or invest in a group resource. Our results help explain why people cooperatively contribute to group resources, suggest how a tragedy of the commons may be avoided, and highlight unifying features in the evolution of cooperation and competition in human and non-human societies.

  20. Development of a group contribution method to predict aqueous phase hydroxyl radical (HO*) reaction rate constants.

    Science.gov (United States)

    Minakata, Daisuke; Li, Ke; Westerhoff, Paul; Crittenden, John

    2009-08-15

    The hydroxyl radical (HO*) is a strong oxidant that reacts with electron-rich sites of organic compounds and initiates complex chain mechanisms. In order to help understand the reaction mechanisms, a rule-based model was previously developed to predict the reaction pathways. For a kinetic model, there is a need to develop a rate constant estimator that predicts the rate constants for a variety of organic compounds. In this study, a group contribution method (GCM) is developed to predict the aqueous phase HO* rate constants for the following reaction mechanisms: (1) H-atom abstraction, (2) HO* addition to alkenes, (3) HO* addition to aromatic compounds, and (4) HO* interaction with sulfur (S)-, nitrogen (N)-, or phosphorus (P)-atom-containing compounds. The GCM hypothesizes that an observed experimental rate constant for a given organic compound is the combined rate of all elementary reactions involving HO*, which can be estimated using the Arrhenius activation energy, E(a), and temperature. Each E(a) for those elementary reactions can be comprised of two parts: (1) a base part that includes a reactive bond in each reaction mechanism and (2) contributions from its neighboring functional groups. The GCM includes 66 group rate constants and 80 group contribution factors, which characterize each HO* reaction mechanism with steric effects of the chemical structure groups and impacts of the neighboring functional groups, respectively. Literature-reported experimental HO* rate constants for 310 and 124 compounds were used for calibration and prediction, respectively. The genetic algorithms were used to determine the group rate constants and group contribution factors. The group contribution factors for H-atom abstraction and HO* addition to the aromatic compounds were found to linearly correlate with the Taft constants, sigma*, and electrophilic substituent parameters, sigma+, respectively. The best calibrations for 83% (257 rate constants) and predictions for 62% (77

  1. Prediction of Hansen Solubility Parameters with a New Group-Contribution Method

    Science.gov (United States)

    Stefanis, Emmanuel; Panayiotou, Costas

    2008-04-01

    A group-contribution method for the estimation of Hansen solubility parameters of pure organic compounds is presented. It uses two kinds of characteristic groups: first-order groups that describe the basic molecular structure of compounds and second-order groups, which are based on the conjugation theory and improve the accuracy of predictions. A large variety of characteristic groups ensure the prediction of Hansen solubility parameters for a broad series of organic compounds, including those having complex multi-ring, heterocyclic, and aromatic structures. The predictions are exclusively based on the molecular structure of compounds, and no experimental data are needed. The predicted values permit a fairly reliable selection of solvents based on the radius of a Hansen solubility parameter sphere or on a Teas parameter ternary plot. Especially designed algorithms permit the preparation of a list of new molecular structures which, if synthesized, could be the ideally suited solvents for a series of corresponding applications.

  2. Risks and benefits of rapid clozapine titration

    Directory of Open Access Journals (Sweden)

    Jeannie D. Lochhead

    2016-05-01

    Full Text Available 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.

  3. Prediction of heat capacities of solid inorganic salts from group contributions

    Energy Technology Data Exchange (ETDEWEB)

    Mostafa, A.T.M.G.; Eakman, J.M. [New Mexico State Univ., Las Cruces, NM (United States). Dept. of Chemical Engineering; Yarbro, S.L. [Los Alamos National Lab., NM (United States)

    1997-01-01

    A group contribution technique is proposed to predict the coefficients in the heat capacity correlation, C{sub p} = a + bT + c/T{sup 2} + dT{sup 2}, for solid inorganic salts. The results from this work are compared with fits to experimental data from the literature. It is shown to give good predictions for both simple and complex solid inorganic salts. Literature heat capacities for a large number (664) of solid inorganic salts covering a broad range of cations (129), anions (17) and ligands (2) have been used in regressions to obtain group contributions for the parameters in the heat capacity temperature function. A mean error of 3.18% is found when predicted values are compared with literature values for heat capacity at 298{degrees} K. Estimates of the error standard deviation from the regression for each additivity constant are also determined.

  4. A rigorous methodology for development and uncertainty analysis of group contribution based property models

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    . The GC model uses the Marrero-Gani (MR) method which considers the group contribution in different levels both functional and structural. The methodology helps improve accuracy and reliability of property modeling and provides a rigorous model quality check and assurance. This is expected to further......Property prediction models are a fundamental tool of process modeling and analysis, especially at the early stage of process development. Furthermore, property prediction models are the fundamental tool for Computer-aided molecular design used for the development of new refrigerants. Group...... contribution (GC) based prediction methods use structurally dependent parameters in order to determine the property of pure components. The aim of the GC parameter estimation is to find the best possible set of model parameters that fits the experimental data. In that sense, there is often a lack of attention...

  5. Estimation of Properties of Pure Organic Substances with Group and Pair Contributions

    Directory of Open Access Journals (Sweden)

    Ourique J.E.S.

    1997-01-01

    Full Text Available ABSTRACTbstract - This work presents a new predictive method for the estimation of properties of pure organic substances. Each compound is assigned a molecular graph or an adjacency matrix representing its chemical structure, from which properties are then obtained as a summation of all contributions associated with functional groups and chemically bonded pairs of groups. The proposed technique is applied to the estimation of critical temperature, critical pressure, critical volume and normal boiling point of 325 organic compounds from different chemical species. Accurate predictions based solely on chemical structure are obtained

  6. Computer-aided polymer design using group contribution plus property models

    DEFF Research Database (Denmark)

    Satyanarayana, Kavitha Chelakara; Abildskov, Jens; Gani, Rafiqul

    2009-01-01

    . Polymer repeat unit property prediction models are required to calculate the properties of the generated repeat units. A systematic framework incorporating recently developed group contribution plus (GC(+)) models and an extended CAMD technique to include design of polymer repeat units is highlighted...... in this paper. The advantage of a GC(+) model in CAMD applications is that a very large number of polymer structures can be considered even though some of the group parameters may not be available. A number of case studies involving different polymer design problems have been solved through the developed...

  7. Analysis and applications of a group contribution sPC-SAFT equation of state

    DEFF Research Database (Denmark)

    Tihic, Amra; von Solms, Nicolas; Michelsen, Michael Locht

    2009-01-01

    A group contribution (GC) method for estimating pure compound parameters for the molecular-based perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) is proposed in a previous work [A. Tihic, G.M. Kontogeorgis, N. von Solms, M.L Michelsen, L Constantinou. Ind. Eng...... method allow satisfactory representation of experimental data of investigated systems with the sPC-SAFT EoS. Moreover, the variety of functional groups in the available GC scheme ensures broad applications of the CC sPC-SAFT EoS....

  8. Midterm peer feedback in problem-based learning groups: the effect on individual contributions and achievement.

    Science.gov (United States)

    Kamp, Rachelle J A; van Berkel, Henk J M; Popeijus, Herman E; Leppink, Jimmie; Schmidt, Henk G; Dolmans, Diana H J M

    2014-03-01

    Even though peer process feedback is an often used tool to enhance the effectiveness of collaborative learning environments like PBL, the conditions under which it is best facilitated still need to be investigated. Therefore, this study investigated the effects of individual versus shared reflection and goal setting on students' individual contributions to the group and their academic achievement. In addition, the influence of prior knowledge on the effectiveness of peer feedback was studied. In this pretest-intervention-posttest study 242 first year students were divided into three conditions: condition 1 (individual reflection and goal setting), condition 2 (individual and shared reflection and goal setting), and condition 3 (control group). Results indicated that the quality of individual contributions to the tutorial group did not improve after receiving the peer feedback, nor did it differ between the three conditions. With regard to academic achievement, only males in conditions 1 and 2 showed better academic achievement compared with condition 3. However, there was no difference between both ways of reflection and goal setting with regard to achievement, indicating that both ways are equally effective. Nevertheless, it is still too early to conclude that peer feedback combined with reflection and goal setting is not effective in enhancing students' individual contributions. Students only had a limited number of opportunities to improve their contributions. Therefore, future research should investigate whether an increase in number of tutorial group meetings can enhance the effectiveness of peer feedback. In addition, the effect of quality of reflection and goal setting could be taken into consideration in future research.

  9. The quantum-chemical determination of group contributions to the thermodynamic properties of organophosphorus compounds

    Science.gov (United States)

    Dorofeeva, O. V.; Ryzhova, O. N.; Moiseeva, N. F.

    2008-06-01

    The enthalpies of formation, entropies, and heat capacities of 95 organophosphorus derivatives calculated by nonempirical quantum-chemical methods were used to develop the additive method for estimating the thermodynamic properties of these compounds. 86 group contribution values were obtained for estimating the thermodynamic properties of diverse organic derivatives of phosphorus in the oxidation states 3 and 5 (three-and four-coordinate phosphorus atoms).

  10. Regular group exercise contributes to balanced health in older adults in Japan: a qualitative study.

    Science.gov (United States)

    Komatsu, Hiroko; Yagasaki, Kaori; Saito, Yoshinobu; Oguma, Yuko

    2017-08-22

    While community-wide interventions to promote physical activity have been encouraged in older adults, evidence of their effectiveness remains limited. We conducted a qualitative study among older adults participating in regular group exercise to understand their perceptions of the physical, mental, and social changes they underwent as a result of the physical activity. We conducted a qualitative study with purposeful sampling to explore the experiences of older adults who participated in regular group exercise as part of a community-wide physical activity intervention. Four focus group interviews were conducted between April and June of 2016 at community halls in Fujisawa City. The participants in the focus group interviews were 26 older adults with a mean age of 74.69 years (range: 66-86). The interviews were analysed using the constant comparative method in the grounded theory approach. We used qualitative research software NVivo10® to track the coding and manage the data. The finding 'regular group exercise contributes to balanced health in older adults' emerged as an overarching theme with seven categories (regular group exercise, functional health, active mind, enjoyment, social connectedness, mutual support, and expanding communities). Although the participants perceived that they were aging physically and cognitively, the regular group exercise helped them to improve or maintain their functional health and enjoy their lives. They felt socially connected and experienced a sense of security in the community through caring for others and supporting each other. As the older adults began to seek value beyond individuals, they gradually expanded their communities beyond geographical and generational boundaries. The participants achieved balanced health in the physical, mental, and social domains through regular group exercise as part of a community-wide physical activity intervention and contributed to expanding communities through social connectedness and

  11. Temporal lobe contribution to perceptual function: A tale of three patient groups.

    Science.gov (United States)

    Behrmann, M; Lee, A C H; Geskin, J Z; Graham, K S; Barense, M D

    2016-09-01

    There has been growing recognition of the contribution of medial and anterior temporal lobe structures to non-mnemonic functions, such as perception. To evaluate the nature of this contribution, we contrast the perceptual performance of three patient groups, all of whom have a perturbation of these temporal lobe structures. Specifically, we compare the profile of patients with focal hippocampal (HC) lesions, those with more extensive lesions to the medial temporal lobe (MTL) that include HC and perirhinal cortex (PrC), and those with congenital prosopagnosia (CP), whose deficit has been attributed to the disconnection of the anterior temporal lobe from more posterior structures. All participants completed a range of'oddity' tasks in which, on each trial, they determined which of four visual stimuli in a display was the'odd-one-out'. There were five stimulus categories including faces, scenes, objects (high and low ambiguity) and squares of different sizes. Comparisons were conducted separately for the HC, MTL and CP groups against their matched control groups and then the group data were compared to each other directly. The group profiles were easily differentiable. Whereas the HC group stood out for its difficulty in discriminating scenes and the CP group stood out for its disproportionate difficulty in discriminating faces with milder effects for scenes and high ambiguity objects, the MTL group evinced a more general discrimination deficit for faces, scenes and high ambiguity objects. The group differences highlight distinct profiles for each of the three groups and distinguish the signature perceptual impairments following more extended temporal lobe alterations. In the recent reconsideration of the role of the hippocampus and neocortex, Moscovitch and colleagues (Moscovitch et al., 2016) note that the medial temporal lobe structures play a role in non-mnemonic functions, such as perception, problem solving, decision-making and language. Here, we address this

  12. Titrated oral misoprostol solution compared with oxytocin for induction of labor in women with unfavorable cervix

    Directory of Open Access Journals (Sweden)

    Akrami M

    2011-10-01

    Full Text Available "nBackground: Uterine contractions and an appropriate cervix are two important factors in labor contributing to good pregnancy outcomes. Oxytocin and prostaglandins, such as misoprostol, are used for the induction of labor. Misoprostol is used for cervical ripening and labor induction. The aim of this trial was to compare the efficacy and safety of titrated oral misoprostol solution with oxytocin for labor induction in pregnant women with an unfavorable cervix."n "nMethods: In this randomized double-blind clinical trial, 140 women with a gestational age of 34-42 weeks and an unfavorable cervix were recruited. The participants had an indication for labor induction and had been referred to the Women's Hospital in Tehran, Iran between January 2010 and January 2011. The participants were randomly assigned to receive 20 µg/hour titrated oral misoprostol plus intravenous placebo or 6 mU/min oxytocin plus oral placebo. In case contractions were inadequate, the drug doses were gradually increased. Pharmacological complications, the mean interval from the start of induction till vaginal delivery and delivery type were monitored and analyzed in both groups."n "nResults: The mean interval from the start of induction till vaginal delivery in misoprostol group was shorter than the oxytocin group (11.07±3.42 vs. 14.87±3.21 hours, P=0.001. The frequency of pharmacological complications and vaginal or cesarean deliveries were similar between the two groups (P>0.05."n "nConclusion: Use of titrated oral misoprostol is a safe and effective method for labor induction in pregnant women with unfavorable cervix. Misoprostol is associated with a shorter interval from induction to vaginal delivery than oxytocin.

  13. Food group contribution of essential elements of the Sao Paulo State market basket

    Energy Technology Data Exchange (ETDEWEB)

    Avegliano, Roseane P.; Maihara, Vera A., E-mail: pagliaro@usp.b, E-mail: vmaihara@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Silva, Fabio F. da, E-mail: ffsusp@uol.com.b [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Matematica e Estatistica. Empresa Junior de Informatica, Matematica e Estatistica

    2009-07-01

    To establish a Market Basket of Sao Paulo state seventy-one foods, with a mean consumption of more than 2 g day{sup -1} per person, were grouped into 30 food categories. The food groups were: cereals, leguminous, leafy vegetables, fruity vegetables, tuberous vegetables, tropical fruits, other fruits, flours, pastas, breads, biscuits, prime grade beef, standard grade beef, pork meats, other meats, poultry, milk/cream, other dairy products, sugars, sweets, salts, sauces, oils, fats, alcoholic beverages, non-alcoholic beverages, coffee, ready-made dishes, saltwater and freshwater fishes. Information about individual food consumption was obtained from a recent national household food budget survey 'POF 2002-2003' conducted by the Brazilian Institute for Geography and Statistics from July 2002 to June 2003. Sampling and kitchen preparation of foods were carried out in restaurants of the University of Sao Paulo. Each food item was individually prepared table-ready. Foods of the same group were mixed, homogenized, pulverized and analyzed for the determination of Ca, Cr, Fe, K, Na and Zn concentrations by Instrumental Neutron Activation Analysis. Average daily intake of each element was calculated by multiplying the element concentration in the food by the corresponding weight of the ready-to-consume food group. The contribution of each food group to the total daily intake of elements by the ready-to-consume food groups of the Market Basket was evaluated. The food groups representing the highest contributions were salts: 79% Na; breads: 37% Fe and 46% Cr; cereals: 19% Zn and milk/cream: 58% Ca and 24% K. (author)

  14. Nap-titration : An effective alternative for continuous positive airway pressure titration

    NARCIS (Netherlands)

    Hoekema, A; Stegenga, B; Meinesz, AF; van der Hoeven, JH; Wijkstra, PJ

    2006-01-01

    When treating Obstructive Steep Apnea-Hypopnea Syndrome (OSAHS) several alternatives for standard (manual) continuous positive airway pressure (CPAP) titration are feasible. A practical alternative is titration without polysomnography during an afternoon nap (Nap-titration). The aim of the present s

  15. Group Ia afferents contribute to short-latency interlimb reflexes in the human biceps femoris muscle

    DEFF Research Database (Denmark)

    Stevenson, Andrew James Thomas; Kamavuako, Ernest Nlandu; Geertsen, Svend Sparre

    2017-01-01

    and velocity of the iKnee rotations. Methods 11 seated participants (mean age: 25 ± 5 years) performed a voluntary isometric knee extension with the ipsilateral leg and contralateral knee flexion to 10% of maximum voluntary contraction (MVC). A mechanical actuator (MTS-Systems Corporation) imposed i...... amplitudes (4 vs. 8°) at the same 150°/s velocity (p’s > 0.08). Conclusion Because fast conducting group Ia muscle spindle afferents are sensitive to changes in muscle stretch velocity, while group II spindle afferents are sensitive to changes in amplitude (Grey et al., JPhysiol., 2001; Matthews, Trends...... Neurosci., 1991), group Ia velocity sensitive muscle spindle afferents likely contribute to the short-latency crossed spinal reflexes in the cBF muscle following iKnee joint rotations. This supports the findings for the short-latency crossed responses in the human soleus muscle (Stubbs & Mrachacz...

  16. Report from the working group on procedures for payment of Member States' contributions

    CERN Document Server

    2000-01-01

    At its Two-hundred-and-forty-second meeting in June 2000*, the Committee of Council decided to set up a Working Group to review the procedures on the payment of contributions of the Member States for the purposes of improving the cash-flow of the Organization. On the basis of its analysis of the different aspects of the problem and of possible solutions and their anticipated impact, the Working Group submits the following recommendations which it considers to be in the best interests of the Organization: - to adopt a revised payment schedule, i.e. payment of 50% not later than 10 February and the remaining 50% not later than 10 June; - to request the Director-General, in addition to the usual reminders sent by the Finance Division, to write to the relevant Minister in the Member State concerned or to take other equivalent action when contributions are outstanding, i.e. payment of over 20% of the total annual contribution is one month late with respect to the adopted payment schedule; - to request the Manageme...

  17. Towards the Development of a Second-Order Approximation in Activity Coefficient Models Based on Group Contributions

    DEFF Research Database (Denmark)

    Abildskov, Jens; Constantinou, Leonidas; Gani, Rafiqul

    1996-01-01

    A simple modification of group contribution based models for estimation of liquid phase activity coefficients is proposed. The main feature of this modification is that contributions estimated from the present first-order groups in many instances are found insufficient since the first-order groups...

  18. Prediction of properties of new halogenated olefins using two group contribution approaches

    DEFF Research Database (Denmark)

    Montagud, Maria E. Mondejar; Cignitti, Stefano; Abildskov, Jens

    2017-01-01

    as refrigerants and solvents, due to their environmentally-friendly features. However there is a lack of experimental data of their thermophysical properties. In this work we present two models based on a group contribution method, using a classical approach and neural networks, to predict the critical...... temperature, critical pressure, normal boiling temperature, acentric factor, and ideal gas heat capacity of organic fluids containing chlorine and/or fluorine. The accuracy of the prediction capacity of the two models is analyzed, and compared with equivalent methods in the literature. The models showed...

  19. Development and Analysis of Group Contribution Plus Models for Property Prediction of Organic Chemical Systems

    DEFF Research Database (Denmark)

    Mustaffa, Azizul Azri

    the molecular fragmentation that relates properties which is the molecular interactions with the molecular structures. One well known and established group-contribution method is the UNIFAC model, used to predict liquid phase activity coefficients for mixtures. The needed values of the group interaction...... parameters (GIPs) are obtained by fitting phase equilibrium data. There are, however many gaps in the UNIFAC parameter table due to lack of data. Alternative to performing measurements, which may not be feasible, values of the missing GIPs, can be predicted through the GCPlus approach. The predicted values...... further developed by including chlorinated and sulfurated VLE systems. Finally, in Chapter 7, the developed Original UNIFAC-CI (VLE/SLE) model has been highlighted in selected case studies involving the design of a working solution for hydrogen peroxide production and solubility investigation...

  20. Surface Titrations of Perlite Suspensions.

    Science.gov (United States)

    Alkan; Do

    1998-11-01

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

  1. Improving Group Contribution Methods by Distance Weighting Amélioration de la méthode de contribution du groupe en pondérant la distance du groupe

    Directory of Open Access Journals (Sweden)

    Zaitseva A.

    2013-03-01

    Full Text Available A novel approach for improving estimations of existing group contribution methods is developed. Instead of fixed contributions, weighted contributions are optimized for each property estimation using a database. These weighting factors are calculated based on similarities between the compound whose properties are estimated and the other compounds in the database. By this approach, those components which are chemically more similar to the estimated one can systematically be given more weight in the estimation process, while sustaining the general nature of the group contribution methods. The new approach was applied to the Joback and Reid (1987, and the Marrero and Gani (2001 group contribution methods. The performances were demonstrated on Normal Boiling Point (NBP predictions. The absolute average error of NBP estimations was reduced by 6.3 K for the Joback and Reid method and by 4 K for the Marrero and Gani method. Other physical properties such as critical pressure, volume, formation energies, melting temperature and fusion enthalpy were estimated by applying the new technique to Joback and Reid method. La nouvelle approche pour améliorer les estimations existantes de la méthode de contribution du groupe est développée. Au lieu d’utiliser les contributions fixes, les contributions pondérées sont optimisées pour chaque propriété de la base de données. Les facteurs de pondération sont calculés en se basant sur les similitudes entre le composé, dont les propriétés sont estimées, et les autres composés de la base de données. En utilisant cette approche, les substances qui sont chimiquement plus proches des substances en question sont systématiquement plus pondérées. Ainsi la nature générale de l’approche est maintenue. La nouvelle technique est appliquée aux méthodes de contribution du groupe de Joback et Reid (1987, ainsi que de Marrero et Gani (2001. Les performances sont démontrées en utilisant la prédiction du

  2. Thermodynamic Modeling of Organic-Inorganic Aerosols with the Group-Contribution Model AIOMFAC

    Science.gov (United States)

    Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.

    2009-04-01

    Liquid aerosol particles are - from a physicochemical viewpoint - mixtures of inorganic salts, acids, water and a large variety of organic compounds (Rogge et al., 1993; Zhang et al., 2007). Molecular interactions between these aerosol components lead to deviations from ideal thermodynamic behavior. Strong non-ideality between organics and dissolved ions may influence the aerosol phases at equilibrium by means of liquid-liquid phase separations into a mainly polar (aqueous) and a less polar (organic) phase. A number of activity models exists to successfully describe the thermodynamic equilibrium of aqueous electrolyte solutions. However, the large number of different, often multi-functional, organic compounds in mixed organic-inorganic particles is a challenging problem for the development of thermodynamic models. The group-contribution concept as introduced in the UNIFAC model by Fredenslund et al. (1975), is a practical method to handle this difficulty and to add a certain predictability for unknown organic substances. We present the group-contribution model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients), which explicitly accounts for molecular interactions between solution constituents, both organic and inorganic, to calculate activities, chemical potentials and the total Gibbs energy of mixed systems (Zuend et al., 2008). This model enables the computation of vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria within one framework. Focusing on atmospheric applications we considered eight different cations, five anions and a wide range of alcohols/polyols as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are very well represented up to high ionic strength. We show that the semi-empirical middle-range parametrization of direct organic-inorganic interactions in alcohol-water-salt solutions enables accurate computations of vapor-liquid and liquid

  3. Determination of titratable acidity in white wine

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2007-01-01

    Full Text Available The amount of titration acid in must is in the largest number of cases with in the range 5.0-8.0 g/dm3. Wines, as a rule, contain less acids than must, and according to Regulations, titratable acidity is in the range of 4.0-8.0 g/dm3 expressed in tartaric acid, because a part of tartaric acid is deposited in the form of salts (tartar or argol during alcohol fermentation. For wines that contain less than 4 g/dm3 of titratable acids there arises a suspicion about their origin, that is, that during the preparation some illegal acts were done. Because of that, the aim of this paper is to determine titratable acidity in white wine, using standard methods of determination, which are compared with the results received by potentiometric titration using ion-selective electrode. According to the received results it can be seen that wine titration with indicator gives sufficient reliable values of wine titration acidity. However, as potentiometric titration at pH value 7.00 is more reliable and objective method, the values of titratable acids content in wine, expressed through tartaric acid, are given according to this result. The analysis of differential potentiometric curves shows that these curves can give us an answer to the question of the presence of a larger amount of other nonorganic substances, which have already existed in wine. However, none of the used methods gives absolutely reliable answer what substances are present in analysed samples.

  4. Contribution of methyl group to secondary organic aerosol formation from aromatic hydrocarbon photooxidation

    Science.gov (United States)

    Li, Lijie; Qi, Li; Cocker, David R.

    2017-02-01

    The complete atmospheric oxidation pathways leading to secondary organic aerosol remain elusive for aromatic compounds including the role of methyl substitutes on oxidation. This study investigates the contribution of methyl group to Secondary Organic Aerosol (SOA) formation during the photooxidation of aromatic hydrocarbons under low NOx condition by applying methyl carbon labeled aromatic hydrocarbons ((13C2) m-xylene and (13C2) p-xylene). Particle and gas phase oxidation products are analyzed by a series of mass spectrometers (HR-TOF-AMS, PTR-MS and SIFT-MS). The methyl group carbon containing oxidation products partition to the particle-phase at a lower rate than the carbons originating from the aromatic ring as a result of ring opening reactions. Further, the methyl carbon in the original aromatic structure is at least 7 times less likely to be oxidized when forming products that partition to SOA than the aromatic ring carbon. Therefore, oxidation of the methyl group in xylenes exerts little impact on SOA formation in current study. This study provides supporting evidence for a recent finding - a similarity in the SOA formation and composition from aromatic hydrocarbons regardless of the alkyl substitutes.

  5. Contributions of object relations theory and self psychology to relational psychology and group psychotherapy.

    Science.gov (United States)

    Schermer, V L

    2000-04-01

    Object relations theory and self psychology are psychoanalytic perspectives that are especially concerned with interpersonal relations and their mental representations. Object relations theory began as an intrapsychic "singleton" psychology with the work of Freud and Melanie Klein. It subsequently evolved into a multi-person psychology with the work of Bion on groups, as well as the clinical and theoretical contributions of Winnicott and Fairbairn. Kohutian self psychology, which emerged later, has been interested in the relations between the self and significant others as mirroring and idealizing "self-objects." Stolorow's "inter-subjective perspective" emerged from self psychology as a full-fledged multi-person point of view. This article considers the significance of contemporary object relations theory and self psychology as relational, multi-person perspectives in terms of their application to group psychotherapy, focusing upon the group-as-a-whole, projective identification, transitional space and object, and self/self-object relations as particularly useful constructs. A clinical vignette is provided.

  6. Prediction of solubility in nonideal multicomponent systems using the UNIFAC group contribution model.

    Science.gov (United States)

    Ochsner, A B; Sokoloski, T D

    1985-06-01

    There is a need to identify suitable blends of solvents to dissolve drugs. Empirical approaches, such as trial-and-error and response surface, require several solubility measurements. In this study the UNIFAC method was used to predict solubility in highly nonideal multicomponent systems in which only the solute enthalpy of fusion and melting point must by measured. UNIFAC combines a group contribution approach with the UNIQUAC model for activity coefficients. Parameters characterizing interactions among constituent groups of a molecule have been previously determined from binary vapor pressure data. These tabulated group parameters are used to predict activity coefficients for newly synthesized compounds. These coefficients, together with the ideal solubility, permit a prediction of solubility. The solubility of 4-hexylresorcinol in ethyl acetate, ethyl myristate, and hexane mixtures was both measured and calculated using UNIFAC. The predicted solubilities were within 10% of the experimental solubilities for all but 3 of 21 mixtures. Since the method accounted for positive and negative deviations from ideality in a hydrogen-bonding system of molecules having different sizes, it shows great potential for use in pharmacy.

  7. Modelling the absorption refrigeration cycle using partially miscible working fluids by group contribution methods

    Science.gov (United States)

    Larkeche, O.; Meniai, A.-H.; Cachot, T.

    2012-06-01

    The present study concerns the cycle performance modelling of a particular configuration of an absorption refrigeration machine based on phase separation as well as development of a strategy for computer aided design of absorbents. The model uses predictive methods based on the group contribution concept for the computation of the thermodynamic phase equilibria involved such as liquid-liquid and vapour-liquid as well as enthalpy-concentration diagrams. The proposed absorbents computer-aided design strategy is based on the exploration of a number of structural group combinations obtained from a selected set of functional groups, according to the chemistry laws. The model was tested on four different absorbent-refrigerant pairs reported in the literature, namely (benzyl ethyl amine-glycerol), (water-hexanoic acid), (water-2-hexanone) and (water-ethyl propionate) as well as on pairs where the absorbent compound is generated by the proposed absorbent design strategy and the refrigerant is water. The results show that quite good values of the coefficient of performance (COP) can be obtained, indicating that this cycle configuration is promising and energetically efficient, mainly due to hardware savings, i.e. absence of condenser. However, other working fluid combinations have to be tested using the proposed model.

  8. Blood selenium levels and contribution of food groups to selenium intake in adolescent girls in Iceland

    Directory of Open Access Journals (Sweden)

    Ingibjorg Gunnarsdottir

    2012-08-01

    Full Text Available Background/objectives: Significant changes have been reported in dietary habits and food availability in Iceland that would be expected to compromise selenium intake and status, especially among young people. These include substantial decreases in the consumption of fish and milk, as well as the selenium content of imported wheat. The aim of this study was to assess selenium in the diet and whole blood of adolescent girls, as well as define the most important foods contributing to intake and blood concentrations of selenium. Design: The subjects were 96 randomly selected girls, aged 16–20, who answered a validated food frequency questionnaire (FFQ for dietary assessment. Selenium intake from each food group was calculated in µg/day. Blood samples were collected for measurement of whole blood selenium. Results: Mean dietary selenium was 51±25 µg/day. Milk/dairy products, including cheese, contributed 36±14% of total dietary selenium; fish 18±12%; and bread/cereal products 13±6%. Mean whole blood selenium was 117±12 µg/l (range 90–208; nearly 90% of subjects were above the optimal level of 100 µg/l. Fish and bread/cereal products were the only foods significantly correlated with selenium in blood (r=0.32; P = 0.002 and r=0.22; P = 0.04, respectively while no correlation was found with milk and dairy products in spite of their greater contribution to total selenium intake. Conclusion: In this population of Icelandic adolescent girls, selenium intake and status seem acceptable. Judging from associations between intake and blood levels, fish and cereals may be the most important contributors to blood selenium.

  9. Evaluation of Group-Contribution Methods to Estimate Vegetable Oils and Biodiesel Properties

    Directory of Open Access Journals (Sweden)

    E. G. Lima Neto

    2012-09-01

    Full Text Available Knowing the phase equilibrium has fundamental importance on mixture separation; and physical and thermodynamic properties of the compounds underlie that equilibrium. Estimation methods are supposed to be a powerful skill for predicting physical and thermodynamic properties of the involved compounds, not only because the large number of properties that can be predicted (vapor pressure, boiling point, melting point, critical properties, etc but also due to the low deviation to experimental measure. This work focuses the prediction of some properties of organic substances present in vegetable oils and in the biodiesel of these oils through group-contribution methods and empiric relations. Estimations were compared to data available on literature and experimental data. This comparison shows satisfactory deviation for application on engineering problems.

  10. Viscosity of heptane-toluene mixtures. Comparison of molecular dynamics and group contribution methods.

    Science.gov (United States)

    Velásquez, Ana Milena; Hoyos, Bibian A

    2017-02-01

    Three methods of molecular dynamics simulation [Green-Kubo (G-K), non-equilibrium molecular dynamics (NEMD) and reversed non-equilibrium molecular dynamics (RNEMD)], and two group contribution methods [UNIFAC-VISCO and Grunberg-Nissan (G-N)] were used to calculate the viscosity of mixtures of n-heptane and toluene (known as heptol). The results obtained for the viscosity and density of heptol were compared with reported experimental data, and the advantages and disadvantages of each method are discussed. Overall, the five methods showed good agreement between calculated and experimental viscosities. In all cases, the deviation was lower than 9%. It was found that, as the concentration of toluene increases, the deviation of the density of the mixture (as calculated with molecular dynamics methods) also increases, which directly affects the viscosity result obtained. Among the molecular simulation techniques evaluated here, G-K produced the best results, and represents the optimal balance between quality of result and time required for simulation. The NEMD method produced acceptable results for the viscosity of the system but required more simulation time as well as the determination of an appropriate shear rate. The RNEMD method was fast and eliminated the need to determine a set of values for shear rate, but introduced large fluctuations in measurements of shear rate and viscosity. The two group contribution methods were accurate and fast when used to calculate viscosity, but require knowledge of the viscosity of the pure compounds, which is a serious limitation for applications in complex multicomponent systems.

  11. From Distraction to Contribution: A Preliminary Study on How Peers Outside the Group Can Contribute to Students’ Learning

    Directory of Open Access Journals (Sweden)

    Victoria Chen

    2015-12-01

    Full Text Available Active Learning Classrooms are new learning spaces that allow collaborative learning activities to take place easily over the traditional classroom. However, some features of these rooms could be viewed as “distracting” to students’ learning such as the multiple interactive screens. The purpose of this paper is to begin the conversation on how subtle roles in the learning environment could impact learning. Using a case study approach, an activity from one course was chosen that exemplified how peers outside students’ immediate group can influence their learning. Based on the preliminary findings, it is suggested that being aware of these subtle roles peers outside the group can have on students and making them explicit in the pedagogical design of the course can lead to maximizing the usage of the space to potentially foster greater learning.

  12. A Group Contribution Method for the Correlation of Static Dielectric Constant of Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    周颖; 林真; 吴可君; 徐国华; 何潮洪

    2014-01-01

    Static dielectric constant is a key parameter to estimate the electro-viscous effect which plays important roles in the flow and convective heat transfer of fluids with ions in microfluidic devices such as micro reactors and heat exchangers. A group contribution method based on 27 groups is developed for the correlation of static dielec-tric constant of ionic liquids in this paper. The ionic liquids considered include imidazolium, pyridinium, pyrrolid-inium, alkylammonium, alkylsulfonium, morpholinium and piperidinium cations and various anions. The data col-lected cover the temperature ranges of 278.15-343.15 K and static dielectric constant ranges of 9.4-85.6. The re-sults of the method show a satisfactory agreement with the literature data with an average absolute relative devia-tion of 7.41%, which is generally of the same order of the experimental data accuracy. The method proposed in this paper provides a simple but reliable approach for the prediction of static dielectric constant of ionic liquids at dif-ferent temperatures.

  13. Titration procedure for low ethoxylated nonionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Buschmann, N. [Anorganisch-Chemisches Inst., Lehrstuhl fuer Analytische Chemie, Muenster Univ. (Germany); Huelskoetter, F. [Anorganisch-Chemisches Inst., Lehrstuhl fuer Analytische Chemie, Muenster Univ. (Germany)

    1997-01-01

    Highly lipophilic surfactants are frequently used as emulsifiers for preparing oil-in-water emulsions (e.g. coolants lubricants). Typical surfactants used for this purpose are low ethoxylated alcohols and ethoxylated alkylphenols. Due to the low degree of ethoxylation they cannot be analysed by conventional methods. The method described in this article is based on the introduction of an anionic group into the molecule by a derivatization reaction. The reaction product can be determined by conventional titration methods for anionic surfactants without any modification. The use of the new method for other nonionic surfactants like sorbitan esters, (ethoxylated) fatty acid amides or glycerol fatty acid partial esters is also described as well as the sample preparation for coolants lubricants. (orig.) [Deutsch] Lipophile Tenside werden haeufig zur Herstellung von Oel-in-Wasser-Emulsionen verwandt, wie sie beispielsweise in Kuehlschmiermitteln eingesetzt werden. Typische Vertreter dieser Tenside sind niedrig ethoxylierte Fettalkohole und Alkylphenole. Wegen ihres geringen Ethoxylierungsgrades koennen sie mit den konventionellen Methoden nicht analytisch bestimmt werden. Die hier beschriebene Analysenmethode beruht auf der Derivatisierung der Ethoxylate zu entsprechenden anionischen Tensiden (Ethersulfate). Diese koennen ohne weiteres mit den etablierten Titrationsverfahren bestimmt werden. Die Anwendung dieses neuen Verfahrens auf die Bestimmung anderer nichtionischer Tenside - Sorbitanester, (ethoxylierte) Fettsaeureamide und Partialglyceride - wird ebenso beschrieben wie die Probenvorbereitung fuer die Analyse von Kuehlschmiermitteln. (orig.)

  14. Titration of gold nanoparticles in phase extraction.

    Science.gov (United States)

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

    2015-12-07

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

  15. The Problem of Free-Riding in Group Projects: Looking beyond Social Loafing as Reason for Non-Contribution

    Science.gov (United States)

    Hall, David; Buzwell, Simone

    2013-01-01

    The increase in popularity of group work in higher education has been accompanied by an increase in the frequency of reports of students not equally contributing to work within the groups. Referred to as "free-riders", the effect of this behaviour on other students can make group work an unpleasant experience for some. Of most…

  16. Heparin and protamine titration do not improve haemostasis in cardiac surgical patients.

    Science.gov (United States)

    Shore-Lesserson, L; Reich, D L; DePerio, M

    1998-01-01

    Weight-based heparin and protamine dosing strategies for cardiopulmonary bypass (CPB) do not take into account interpatient variability in drug sensitivity and may result in bleeding complications. We compared the Hemochron RxDx heparin and protamine titration system with standard weight based management with regard to heparin dose, protamine dose, and perioperative bleeding. One hundred and thirty-five cardiac surgical patients were randomised into four groups. Group 1 received standard heparin and protamine management: Group 2 received heparin and protamine by in vitro titration. Group 3 had the heparin dose titrated, and group 4 had the protamine dose titrated. Coagulation tests, bleeding, and transfusion requirements were measured. The initial heparin bolus predicted by the titration was < 300 U.kg-1 in all patients. Group 2 received a lower heparin bolus for the initiation of bypass but total heparin doses were not different among groups (group 1 = 365 +/- 43, group 2 = 348 +/- 73 U.kg-1, group 3 = 394 +/- 86 U.kg-1, group 4 = 376 +/- 60; P = 0.06). Groups 2 and 4 received a lower initial and a lower total protamine dose (total dose group 1 = 4.03 +/- 0.65 mg.kg-1, group 2 = 3.56 +/- 1.11 mg.kg-1, group 3 = 4.22 +/- 0.90 mg.kg-1, group 4 = 3.38 +/- 0.98 mg.kg-1, P = 0.001). The incidences of incomplete heparin neutralisation (P = 0.14) and heparin rebound (P = 0.1) were not different among groups. Postoperative bleeding and transfusion requirements did not differ. In cardiac surgical patients, heparin and protamine titration did predict a lower protamine dose but did not result in a measurable improvement in haemostasis during the perioperative period.

  17. Volumetric behaviour of amino acids and their group contributions in aqueous lactose solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Amalendu, E-mail: palchem@sify.co [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India); Chauhan, Nalin [Department of Chemistry, Kurukshetra University, Kurukshetra 136 119 (India)

    2011-02-15

    Densities, {rho}, for glycine, L-alanine, L-valine, and L-leucine [(0.05 to 0.30) m] in aqueous lactose solutions ranging from pure water to 6 mass% lactose were determined at T = (293.15, 298.15, 303.15, and 308.15) K. The density was used to compute apparent molar volume, V{sub {phi}}, partial molar volume at infinite dilution, V{sub {phi}}{sup o}, and experimental slope, S{sub V} were obtained and interpreted in terms of solute-solvent and solute-solute interactions. These data were used to calculate the ({partial_derivative}V{sub {phi}}{sup 0}/{partial_derivative}T){sub P} values. The partial molar volume of transfer, {Delta}V{sub {phi}}{sup 0} from water to aqueous lactose solutions at infinite dilution has also been calculated. In addition to this, the linear correlation of V{sub {phi}}{sup 0} with number of carbon atoms in the alkyl chain of amino acids was utilized to determine the respective contributions of NH{sub 3}{sup +}COO{sup -}, and CH{sub 2} groups to V{sub {phi}}{sup 0}.

  18. Group-contribution based property estimation and uncertainty analysis for flammability-related properties.

    Science.gov (United States)

    Frutiger, Jérôme; Marcarie, Camille; Abildskov, Jens; Sin, Gürkan

    2016-11-15

    This study presents new group contribution (GC) models for the prediction of Lower and Upper Flammability Limits (LFL and UFL), Flash Point (FP) and Auto Ignition Temperature (AIT) of organic chemicals applying the Marrero/Gani (MG) method. Advanced methods for parameter estimation using robust regression and outlier treatment have been applied to achieve high accuracy. Furthermore, linear error propagation based on covariance matrix of estimated parameters was performed. Therefore, every estimated property value of the flammability-related properties is reported together with its corresponding 95%-confidence interval of the prediction. Compared to existing models the developed ones have a higher accuracy, are simple to apply and provide uncertainty information on the calculated prediction. The average relative error and correlation coefficient are 11.5% and 0.99 for LFL, 15.9% and 0.91 for UFL, 2.0% and 0.99 for FP as well as 6.4% and 0.76 for AIT. Moreover, the temperature-dependence of LFL property was studied. A compound specific proportionality constant (K(LFL)) between LFL and temperature is introduced and an MG GC model to estimate K(LFL) is developed. Overall the ability to predict flammability-related properties including the corresponding uncertainty of the prediction can provide important information for a qualitative and quantitative safety-related risk assessment studies.

  19. Improved group contribution parameter set for the application of solubility parameters to melt extrusion.

    Science.gov (United States)

    Just, Susann; Sievert, Frank; Thommes, Markus; Breitkreutz, Jörg

    2013-11-01

    Hot-melt extrusion is gaining importance for the production of amorphous solid solutions; in parallel, predictive tools for estimating drug solubility in polymers are increasingly demanded. The Hansen solubility parameter (SP) approach is well acknowledged for its predictive power of the miscibility of liquids as well as the solubility of some amorphous solids in liquid solvents. By solely using the molecular structure, group contribution (GC) methods allow the calculation of Hansen SPs. The GC parameter sets available were derived from liquids and polymers which conflicts with the object of prediction, the solubility of solid drugs. The present study takes a step from the liquid based SPs toward their application to solid solutes. On the basis of published experimental Hansen SPs of solid drugs and excipients only, a new GC parameter set was developed. In comparison with established parameter sets by van Krevelen/Hoftyzer, Beerbower/Hansen, Breitkreutz and Stefanis/Panayiotou, the new GC parameter set provides the highest overall predictive power for solubility experiments (correlation coefficient r = -0.87 to -0.91) as well as for literature data on melt extrudates and casted films (r = -0.78 to -0.96).

  20. End-point construction and systematic titration error in linear titration curves-complexation reactions

    NARCIS (Netherlands)

    Coenegracht, P.M.J.; Duisenberg, A.J.M.

    1975-01-01

    The systematic titration error which is introduced by the intersection of tangents to hyperbolic titration curves is discussed. The effects of the apparent (conditional) formation constant, of the concentration of the unknown component and of the ranges used for the end-point construction are consid

  1. A generalized approach for the calculation and automation of potentiometric titrations Part 2. Redox Titrations

    NARCIS (Netherlands)

    Stur, J.; Bos, M.; van der Linden, W.E.

    1984-01-01

    The very fast calculation procedure described earlier is applied to calculate the titration curves of complicated redox systems. The theory is extended slightly to cover inhomogeneous redox systems. Titrations of iodine or 2,6-dichloroindophenol with ascorbic acid are described. It is shown that cor

  2. Group-contribution+ (GC+) based estimation of properties of pure components: Improved property estimation and uncertainty analysis

    DEFF Research Database (Denmark)

    Hukkerikar, Amol; Sarup, Bent; Ten Kate, Antoon

    2012-01-01

    The aim of this work is to present revised and improved model parameters for group-contribution+ (GC+) models (combined group-contribution (GC) method and atom connectivity index (CI) method) employed for the estimation of pure component properties, together with covariance matrices to quantify.......g. prediction errors in terms of 95% confidence intervals) in the estimated property values. This feature allows one to evaluate the effects of these uncertainties on product-process design, simulation and optimization calculations, contributing to better-informed and more reliable engineering solutions. (C...

  3. Estimation of Properties of Pure Components Using Improved Group-Contribution+ (GC+) Based Models and Uncertainty Analysis

    DEFF Research Database (Denmark)

    Hukkerikar, Amol; Sarup, Bent; Abildskov, Jens

    they must be estimated. Predictive methods such as the group-contribution+ (GC+) method (combined group-contribution (GC) method and atom connectivity index (CI) method) are generally suitable to estimate the needed property values. For assessing the quality and reliability of the selected property...... the estimated property values using the GC+ approach, but also the uncertainties in the estimated property values. This feature allows one to evaluate the effects of these uncertainties on the product-process design calculations thereby contributing to better-informed and reliable engineering solutions....

  4. Diverse Bacterial Groups Contribute to the Alkane Degradation Potential of Chronically Polluted Subantarctic Coastal Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Guibert, Lilian M.; Loviso, Claudia L.; Borglin, Sharon; Jansson, Janet K.; Dionisi, Hebe M.; Lozada, Mariana

    2015-11-07

    We aimed to gain insight into the alkane degradation potential of microbial communities from chronically polluted sediments of a subantarctic coastal environment using a combination of metagenomic approaches. A total of 6178 sequences annotated as alkane-1-monooxygenases (EC 1.14.15.3) were retrieved from a shotgun metagenomic dataset that included two sites analyzed in triplicate. The majority of the sequences binned with AlkB described in Bacteroidetes (32 ± 13 %) or Proteobacteria (29 ± 7 %), although a large proportion remained unclassified at the phylum level. Operational taxonomic unit (OTU)-based analyses showed small differences in AlkB distribution among samples that could be correlated with alkane concentrations, as well as with site-specific variations in pH and salinity. A number of low-abundance OTUs, mostly affiliated with Actinobacterial sequences, were found to be only present in the most contaminated samples. On the other hand, the molecular screening of a large-insert metagenomic library of intertidal sediments from one of the sampling sites identified two genomic fragments containing novel alkB gene sequences, as well as various contiguous genes related to lipid metabolism. Both genomic fragments were affiliated with the phylum Planctomycetes, and one could be further assigned to the genus Rhodopirellula due to the presence of a partial sequence of the 23S ribosomal RNA (rRNA) gene. This work highlights the diversity of bacterial groups contributing to the alkane degradation potential and reveals patterns of functional diversity in relation with environmental stressors in a chronically polluted, high-latitude coastal environment. In addition, alkane biodegradation genes are described for the first time in members of Planctomycetes.

  5. Regulation of Polysaccharide Utilization Contributes to the Persistence of Group A Streptococcus in the Oropharynx▿

    Science.gov (United States)

    Shelburne, Samuel A.; Okorafor, Nnaja; Sitkiewicz, Izabela; Sumby, Paul; Keith, David; Patel, Payal; Austin, Celest; Graviss, Edward A.; Musser, James M.

    2007-01-01

    Group A Streptococcus (GAS) genes that encode proteins putatively involved in polysaccharide utilization show growth phase-dependent expression in human saliva. We sought to determine whether the putative polysaccharide transcriptional regulator MalR influences the expression of such genes and whether MalR helps GAS infect the oropharynx. Analysis of 32 strains of 17 distinct M protein serotypes revealed that MalR is highly conserved across GAS strains. malR transcripts were detectable in patients with GAS pharyngitis, and the levels increased significantly during growth in human saliva compared to the levels during growth in glucose-containing or nutrient-rich media. To determine if MalR influenced the expression of polysaccharide utilization genes, we compared the transcript levels of eight genes encoding putative polysaccharide utilization proteins in the parental serotype M1 strain MGAS5005 and its ΔmalR isogenic mutant derivative. The transcript levels of all eight genes were significantly increased in the ΔmalR strain compared to the parental strain, especially during growth in human saliva. Following experimental infection, the ΔmalR strain persistently colonized the oropharynx in significantly fewer mice than the parental strain colonized, and the numbers of ΔmalR strain CFU recovered were significantly lower than the numbers of the parental strain CFU recovered. These data led us to conclude that MalR influences the expression of genes putatively involved in polysaccharide utilization and that MalR contributes to the persistence of GAS in the oropharynx. PMID:17403878

  6. Diverse Bacterial Groups Contribute to the Alkane Degradation Potential of Chronically Polluted Subantarctic Coastal Sediments.

    Science.gov (United States)

    Guibert, Lilian M; Loviso, Claudia L; Borglin, Sharon; Jansson, Janet K; Dionisi, Hebe M; Lozada, Mariana

    2016-01-01

    We aimed to gain insight into the alkane degradation potential of microbial communities from chronically polluted sediments of a subantarctic coastal environment using a combination of metagenomic approaches. A total of 6178 sequences annotated as alkane-1-monooxygenases (EC 1.14.15.3) were retrieved from a shotgun metagenomic dataset that included two sites analyzed in triplicate. The majority of the sequences binned with AlkB described in Bacteroidetes (32 ± 13 %) or Proteobacteria (29 ± 7 %), although a large proportion remained unclassified at the phylum level. Operational taxonomic unit (OTU)-based analyses showed small differences in AlkB distribution among samples that could be correlated with alkane concentrations, as well as with site-specific variations in pH and salinity. A number of low-abundance OTUs, mostly affiliated with Actinobacterial sequences, were found to be only present in the most contaminated samples. On the other hand, the molecular screening of a large-insert metagenomic library of intertidal sediments from one of the sampling sites identified two genomic fragments containing novel alkB gene sequences, as well as various contiguous genes related to lipid metabolism. Both genomic fragments were affiliated with the phylum Planctomycetes, and one could be further assigned to the genus Rhodopirellula due to the presence of a partial sequence of the 23S ribosomal RNA (rRNA) gene. This work highlights the diversity of bacterial groups contributing to the alkane degradation potential and reveals patterns of functional diversity in relation with environmental stressors in a chronically polluted, high-latitude coastal environment. In addition, alkane biodegradation genes are described for the first time in members of Planctomycetes.

  7. Natural Monocrystalline Pyrite as Sensor for Potentiometric Redox Titrations. Part I. Titrations with Permanganate

    Directory of Open Access Journals (Sweden)

    B. V. Vukanovic

    2002-04-01

    Full Text Available Results obtained in potentiometric titrations of Fe(II, Mn(II, Fe(CN64-, C2O42- and As(III with standard potassium permanganate solution, are presented. The titration end point (TEP was detected with a universal electrode whose sensor is natural crystalline pyrite. The titrations of As(III were carried out in HCl (1.2 M and H2SO4 solutions (0.1- 4.5 M, whereas oxalate was determined in H2SO4 (0.1-4.5 M. Iron(II and hexacyanoferrate(II were titrated in H2SO4 and also in H3PO4 solutions (0.1-4.5 M. The titrations of Mn(II were performed in H2P2O72- media at pH 4.0, 5.0, 6.0 and 7.0. The results obtained by using the pyrite electrode were compared with those obtained by the application of a Pt-electrode, and good agreement, reproducibility and accuracy were obtained. The potentials in the course of the titration and at the end-point (TEP are rapidly established. The potential changes at the TEP ranged from 90 to 330 mV/0.1 mL, depending on the titrated system. The highest changes were observed in titrations of Fe(II in H3PO4 (240-330 mV/0.1 mL. Reversed titrations were also performed and accurate and reproducible results were obtained.

  8. Contribution of DNA Repair Xeroderma Pigmentosum Group D Genotypes to Colorectal Cancer Risk in Taiwan.

    Science.gov (United States)

    Chang, Wen-Shin; Yueh, Te-Cheng; Tsai, Chia-Wen; Ji, Hong-Xue; Wu, Cheng-Nan; Wang, Shou-Cheng; Lai, Yi-Liang; Hsu, Shih-Wei; Hsieh, Ming-Hao; Hsiao, Chieh-Lun; Hung, Yi-Wen; Shih, Tzu-Ching; Bau, Da-Tian

    2016-04-01

    It has been previously proposed that genetic variations on DNA repair genes confer susceptibility to cancer and the DNA repair gene Xeroderma Pigmentosum Group D (XPD) is thought to play the role of a helicase during excision repair and transcription. We investigated three genotypes of XPD, at promoter -114 (rs3810366), Asp312Asn (rs1799793) and Lys751Gln (rs13181), regarding their association with colorectal cancer susceptibility in a Taiwanese population. In total, 362 patients with colorectal cancer and 362 gender- and age-matched healthy controls were genotyped by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP), and their XPD genotypes' association with colorectal cancer risk was investigated. The genotypes of XPD Asp312Asn (p=0.2493), Lys751Gln (p=0.7547) and promoter -114 (p=0.8702), were not associated with susceptibility for colorectal cancer. The Chi-square test revealed that the variant alleles of XPD Asp312Asn, Lys751Gln and promoter -114 was not associated with susceptibility for colorectal cancer either [p=0.1330, 0.3888 and 0.8740; odds ratio (OR)=1.20, 0.83 and 0.98; 95% confidence interval (95%CI)=0.95-1.52, 0.54-1.27 and 0.80-1.21, respectively]. The risk of A/G and A/A genotypes have no association with cancer risk among non-alcohol drinkers (OR=1.24, 95%, CI=0.90-1.72, p=0.2103) or alcohol drinkers (OR=1.51, 95% CI=0.64-3.55, p=0.4648). There exists no obvious contribution of XPD genotypes to tumor size (p=0.3531), location (p=0.3006) and lymph node metastasis (p=0.1061). Asp312Asn, Lys751Gln and promoter -114 of the XPD gene were not found to be adequate predictive markers for colorectal cancer risk in Taiwan. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  9. The contribution of rural institutions to rural development: Study of smallholder farmer groups and NGOs in Uganda

    OpenAIRE

    2015-01-01

    This paper presents results from a quantitative analysis of the contribution of nongovernmental organisations (NGOs) and smallholder farmer groups as sample rural institutions in addressing four main rural developmental objectives via improving health, education, agriculture and industry. The study involved 87 respondents from 40 organizations including19 NGOs and 21 smallholder farmer groups from central region of Uganda. Data from questionnaires, focus group discussions, interviews, key inf...

  10. The contribution of adenines in the catalytic core of 10-23 DNAzyme improved by the 6-amino group modifications.

    Science.gov (United States)

    Zhu, Junfei; Li, Zhiwen; Wang, Qi; Liu, Yang; He, Junlin

    2016-09-15

    In the catalytic core of 10-23 DNAzyme, its five adenine residues are moderate conservative, but with highly conserved functional groups like 6-amino group and 7-nitrogen atom. It is this critical conservation that these two groups could be modified for better contribution. With 2'-deoxyadenosine analogues, several functional groups were introduced at the 6-amino group of the five adenine residues. 3-Aminopropyl substituent at 6-amino group of A15 resulted in a five-fold increase of kobs. More efficient DNAzymes are expected by delicate design of the linkage and the external functional groups for this 6-amino group of A15. With this modification approach, other functional groups or residues could be optimized for 10-23 DNAzyme.

  11. Isothermal Titration Calorimetry in the Student Laboratory

    Science.gov (United States)

    Wadso, Lars; Li, Yujing; Li, Xi

    2011-01-01

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

  12. Isothermal Titration Calorimetry in the Student Laboratory

    Science.gov (United States)

    Wadso, Lars; Li, Yujing; Li, Xi

    2011-01-01

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

  13. Dorsomedial prefrontal cortex and cerebellar contribution to in-group attitudes: a transcranial magnetic stimulation study.

    Science.gov (United States)

    Gamond, Lucile; Ferrari, Chiara; La Rocca, Stefania; Cattaneo, Zaira

    2017-04-01

    We tend to express more positive judgments and behaviors toward individuals belonging to our own group compared to other (out-) groups. In this study, we assessed the role of the cerebellum and of the dorsomedial prefrontal cortex (dmPFC) - two regions critically implicated in social cognition processes - in mediating implicit valenced attitudes toward in-group and out-group individuals. To this aim, we used transcranial magnetic stimulation (TMS) in combination with a standard attitude priming task, in which Caucasian participants had to categorize the valence of a series of adjectives primed by either an in-group or an out-group face. In two behavioral experiments, we found an in-group bias (i.e. faster categorization of positive adjectives when preceded by in-group faces) but no evidence of an out-group bias. Interestingly, TMS over both the dmPFC and over the (right) cerebellum significantly interfered with the modulation exerted by group membership on adjective valence classification, abolishing the in-group bias observed at baseline. Overall, our data suggest that both the dmPFC and the cerebellum play a causal role in mediating implicit social attitudes.

  14. 77 FR 59238 - Call for Expert Reviewers to the U.S. Government Review of the Working Group I Contribution to...

    Science.gov (United States)

    2012-09-26

    ... Expert Reviewers to the U.S. Government Review of the Working Group I Contribution to the Fifth... Department of State, request expert review of the Second Order Draft of the Working Group I Contribution to... the Working Group I contribution to the 5th Assessment Report (Working Group I Table of...

  15. Titration Calorimetry Standards and the Precision of Isothermal Titration Calorimetry Data

    Science.gov (United States)

    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

  16. Contributions of the European trials (European randomized screening group) in computed tomography lung cancer screening

    NARCIS (Netherlands)

    Heuvelmans, Marjolein A; Vliegenthart, Rozemarijn; Oudkerk, Matthijs

    2015-01-01

    Lung cancer is the leading cause of cancer-related death worldwide. In 2011, the largest lung cancer screening trial worldwide, the US National Lung Screening Trial, published a 20% decrease in lung cancer-specific mortality in the computed tomography (CT)-screened group, compared with the group scr

  17. Contributions of the European trials (European randomized screening group) in computed tomography lung cancer screening

    NARCIS (Netherlands)

    Heuvelmans, Marjolein A; Vliegenthart, Rozemarijn; Oudkerk, Matthijs

    Lung cancer is the leading cause of cancer-related death worldwide. In 2011, the largest lung cancer screening trial worldwide, the US National Lung Screening Trial, published a 20% decrease in lung cancer-specific mortality in the computed tomography (CT)-screened group, compared with the group

  18. Computational titration analysis of a multiprotic HIV-1 protease-ligand complex.

    Science.gov (United States)

    Spyrakis, Francesca; Fornabaio, Micaela; Cozzini, Pietro; Mozzarelli, Andrea; Abraham, Donald J; Kellogg, Glen E

    2004-09-29

    A new computational method for analyzing the protonation states of protein-ligand complexes with multiple ionizable groups is applied to the structurally characterized complex between the peptide Glu-Asp-Leu and HIV-1 protease. This complex has eight ionizable groups at the active site: four from the ligand and four Asp residues on the protein. Correlation, with an error of ca. 0.6 kcal mol-1, is made between the calculated titration curve and the experimental titration curve. The analysis suggests that between four and five of the eight ionizable groups are protonated at the pH of crystallization.

  19. An Olfactory Indicator for Acid-Base Titrations.

    Science.gov (United States)

    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)

  20. Titratable acidity of beverages influences salivary pH recovery

    Directory of Open Access Journals (Sweden)

    Livia Maria Andaló TENUTA

    2015-01-01

    Full Text Available 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.

  1. Titratable acidity of beverages influences salivary pH recovery.

    Science.gov (United States)

    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 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.

  2. Telephone titration of heart failure medications.

    Science.gov (United States)

    Steckler, Anne E; Bishu, Kalkidan; Wassif, Heba; Sigurdsson, Gardar; Wagner, Judy; Jaenicke, Connie; Vats, Shashank; Rector, Thomas; Anand, Inder S

    2011-01-01

    In clinical practice, heart failure (HF) medications are underused and prescribed at lower than recommended doses. Telephone care is an option that could help to titrate HF medication in a timely manner. We describe our experience of a nurse-run, cardiologist- or nurse practitioner-supervised clinic to up-titrate HF medications via telephone. Patients with the diagnosis of HF, New York Heart Association classes I to III, were referred to a registered nurse-run, cardiologist-/nurse practitioner-supervised HF medication titration clinic. Clinical and medication data collected at enrollment to the clinic and at 3 to 6 months after optimization of HF medications in patients who did or did not reach the target doses were compared. Effect on left ventricular (LV) function was also evaluated. There were 79 patients in the evaluation: 64 with HF and LV systolic dysfunction (LVSD) and the remaining 15 with HF and preserved ejection fraction (EF). Seventy-two percent of patients with LVSD were on an angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB), and 61% were on a β-blocker at baseline, and this increased to 98% and 97%, respectively, after optimization. Target doses was achieved in 50% of patients for ACEI or ARB, and in 41% for β-blockers. The median time to optimization was 54 days (interquartile range, 20-97 days). The average number of phone calls at the time of optimization were 5.4 (SD, 3.7), and the average number of clinic visits was 1.9 (SD, 1.3). Reasons for not reaching the target doses included hypotension, hyperkalemia, and renal dysfunction for ACEI and bradycardia for β-blockers. Overall, the EF increased by 10% (SD, 10%) after 6 months, and 35% or greater in 42% of patients whose baseline EF was less than 35%. There were no adverse events related to the dose up-titration. Telephonic titration of HF medications was feasible and safe and was achieved in 97% patients on ACEI/ARB and β-blockers. Medication titration was

  3. Wade's and Gelso's Contribution to the New Psychology of Men: Male Reference Group Dependence Theory.

    Science.gov (United States)

    O'Neil, James M.

    1998-01-01

    Relates Wade's and Gelso's Male Reference Group Dependence Theory to past and present literature in the new psychology of men. Points out the strengths of the ideas and data; reflects on where the theory needs more clarification and extension. (MKA)

  4. 29 CFR 4043.29 - Change in contributing sponsor or controlled group.

    Science.gov (United States)

    2010-07-01

    ... knowledge of the transaction and of the controlled group relationship; and (3) Press releases; Forms 10Q. If... become effective by the 30th day, Company R has the reporting obligation. (3) Merger/consolidation within...

  5. Multi-Output Recommender: Items, Groups and Friends, and Their Mutual Contributing Effects

    CERN Document Server

    Zeng, Wei

    2012-01-01

    Up to now, more and more online sites have started to allow their users to build the social relationships. Take the Last.fm for example, users could not only add each other as friends, but also join interest groups that include people with common tastes. Therefore, in this environment, users might be interested in not only receiving item recommendations, but also getting suggestion of friends whom they might put in the contact list, and recommendation of interest groups that they could consider to join. To support such needs, in this paper, we propose a generalized framework that provides three different types of recommendation in a single system: recommending items, recommending groups and recommending friends. For each type of recommendation, we in depth investigate the respective roles of other two information resources (e.g., user-item preferences and friendship for recommending groups), along with their combined effect. The experiment reveals the ideal fusion mechanism for the multi-output recommendation...

  6. EFL Arab Learners' Peer Revision of Writing in a Facebook Group: Contributions to Written Texts and Sense of Online Community

    Science.gov (United States)

    Razak, Norizan Abdul; Saeed, Murad Abdu

    2015-01-01

    This qualitative study investigated peer writing revision among English as foreign language (EFL) Arab students in a Facebook group. Specifically, it aimed to identify the text revisions made by the learners and to determine their contributions to the learners' written texts and sense of online community outside the college classroom context.…

  7. "Dealing With" Unexpected Learner Contributions in Whole Group Activities: An Examination of Novice Language Teacher Discursive Practices

    Science.gov (United States)

    Fagan, Drew S.

    2012-01-01

    The current paper examines the discursive practices of one novice English as a Second Language (ESL) teacher "dealing with" learners' unexpected contributions in whole group classroom interactions during teacher- and learner-initiated sequences-of-talk. The study draws from two fields of research: classroom discourse studies…

  8. There's always a villain to punish: group processes contributing to violence and its remediation.

    Science.gov (United States)

    Thomas, Nina K

    2015-01-01

    This paper considers the widespread use of violent metaphors, such as "combat" and "war," to represent the current social, psychological, and political problems within the United States. I apply Lakoff and Johnson's (1980) thesis that metaphor shapes thought, policy, and behavior. I examine how use of such metaphors inclines the national consciousness toward violence and punishment for it. In addition, I discuss shame and humiliation as psychological precursors of violence, particularly as these play out in the exclusion and extrusion via group scapegoating of individuals and whole groups from active participation in an esteemed or powerful other group. Included within the concept of "violence" are those harmful social policies that invalidate the experiences of disempowered people within the United States. I consider the role of group processes in resolving the injuries wrought by violence, particularly as these operate within such restorative justice projects as the Glencree Ex-Combatants Programme in Northern Ireland. Lessons emerge from restorative justice projects installed internationally for ameliorating conflict within and between "victim" groups in the United States.

  9. Kinetic titration series with biolayer interferometry.

    Science.gov (United States)

    Frenzel, Daniel; Willbold, Dieter

    2014-01-01

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

  10. Kinetic titration series with biolayer interferometry.

    Directory of Open Access Journals (Sweden)

    Daniel Frenzel

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

  11. Some analytical methods for explosives. Part V. [Various forms of chromatography, photometry, serial extraction, and non-aqueous titration

    Energy Technology Data Exchange (ETDEWEB)

    Selig, W.

    1976-09-13

    A collection of methods suitable for routine performance by technicians for analyzing explosives is presented. The techniques employed include various forms of chromatography, photometry, serial extraction, and nonaqueous titration. A final section discusses methods of analysis of organic functional groups.

  12. A Systematic Methodology for Uncertainty Analysis of Group Contribution Based and Atom Connectivity Index Based Models for Estimation of Properties of Pure Components

    OpenAIRE

    Hukkerikar, Amol; Sarup, Bent; Sin, Gürkan; Gani, Rafiqul

    2011-01-01

    One of the most widely employed group contribution method for estimation of properties of pure components is the Marrero and Gani (MG) method. For the given component whose molecular structure is not completely described by any of the available groups, group contribution+ method (combined MG method and atomic connectivity index method) has been employed to create the missing groups and predict their contributions through the regressed contributions of connectivity indices. The objective of th...

  13. The Working Group on Meteor Showers Nomenclature: a History, Current Status and a Call for Contributions

    Science.gov (United States)

    Jopek, T. J.; Jenniskens, P. M.

    2011-01-01

    During the IAU General Assembly in Rio de Janeiro in 2009, the members of Commission 22 established the Working Group on Meteor Shower Nomenclature, from what was formerly the Task Group on Meteor Shower Nomenclature. The Task Group had completed its mission to propose a first list of established meteor showers that could receive officially names. At the business meeting of Commission 22 the list of 64 established showers was approved and consequently officially accepted by the IAU. A two-step process is adopted for showers to receive an official name from the IAU: i) before publication, all new showers discussed in the literature are first added to the Working List of Meteor Showers, thereby receiving a unique name, IAU number and three-letter code; ii) all showers which come up to the verification criterion are selected for inclusion in the List of Established Meteor Showers, before being officially named at the next IAU General Assembly.

  14. Titration force microscopy on supported lipid bilayers.

    Science.gov (United States)

    Garcia-Manyes, Sergi; Gorostiza, Pau; Sanz, Fausto

    2006-01-01

    The use of chemically modified atomic force microscopy (AFM) probes allows us to measure the surface charges of supported planar lipid bilayers with high sensitivity through the force spectroscopy operation mode. By controlling the chemistry of the tip, we can perform a classical analytical chemistry titration where the titration agent is a weak acid (attached to the AFM tip) with the particularity of being performed in surface rather than in solution and, especially, at the nanometric scale. Thus, the AFM tip acts as a real "nanosensor". The approaching curves of the force plots reveal that electrostatic interactions between the tip and the supported membrane play a key role. Besides, the plot of the adhesion force (measured from the retracting curve of the force plots) versus pH displays a nonsigmoidal shape with a peak in the adhesion force attributed to high-energy hydrogen bonds. One of these peaks corresponds to the pKa of the surface under study and the other to the pKa of the titrating probe attached to the tip.

  15. 78 FR 19565 - Call for Expert Reviewers to the U.S. Government Review of the Working Group II Contribution to...

    Science.gov (United States)

    2013-04-01

    ... Expert Reviewers to the U.S. Government Review of the Working Group II Contribution to the Fifth... State, request expert review of the Second Order Draft of the Working Group II Contribution to the Fifth..._procedures.shtml In October 2009, the IPCC approved the outline for the Working Group II contribution to...

  16. 78 FR 12807 - Call for Expert Reviewers to the U.S. Government Review of the Working Group III Contribution to...

    Science.gov (United States)

    2013-02-25

    ... Expert Reviewers to the U.S. Government Review of the Working Group III Contribution to the Fifth..., request expert review of the Second Order Draft of the Working Group III Contribution to the Fifth..._procedures.shtml . In October 2009, the IPCC approved the outline for the Working Group III contribution...

  17. Development of a group contribution method for determination of viscosity of ionic liquids at atmospheric pressure

    DEFF Research Database (Denmark)

    Gharagheizi, Farhad; Ilani-Kashkouli, Poorandokht; Mohammadi, Amir H.

    2012-01-01

    In this study, a wide literature survey has been carried out to collect an extensive set of liquid viscosity data for ionic liquids (ILs). A data set consisting of 1672 viscosity values and comprising 443 ILs was collated from 204 different literature sources. Using this data set, a reliable group...

  18. Making Group Assessment Transparent: What Wikis Can Contribute to Collaborative Projects

    Science.gov (United States)

    Caple, Helen; Bogle, Mike

    2013-01-01

    This paper investigates the use of new media technologies, in particular wikis, for the compiling and grading of group assessment tasks. Wikis are open web pages that can be viewed and modified by anyone with internet access and are well known for their collaborative nature. Wikis are also transparent, which means that any edit/modification is…

  19. Modeling of the Critical Micelle Concentration (CMC) of Nonionic Surfactants with an Extended Group-Contribution Method

    DEFF Research Database (Denmark)

    Mattei, Michele; Kontogeorgis, Georgios; Gani, Rafiqul

    2013-01-01

    A group-contribution (GC) property prediction model for estimating the critical micelle concentration (CMC) of nonionic surfactants in water at 25 °C is presented. The model is based on the Marrero and Gani GC method. A systematic analysis of the model performance against experimental data......; and carbohydrate derivate ethers, esters, and thiols. The model developed consists of linear group contributions, and the critical micelle concentration is estimated using the molecular structure of the nonionic surfactant alone. Compared to other models used for the prediction of the critical micelle...... is carried out using data for a wide range of nonionic surfactants covering a wide range of molecular structures. As a result of this procedure, new third order groups based on the characteristic structures of nonionic surfactants are defined and are included in the Marrero and Gani GC model. In this way...

  20. Water absorption in PEEK and PEI matrices. Contribution to the understanding of water-polar group interactions

    Science.gov (United States)

    Courvoisier, E.; Bicaba, Y.; Colin, X.

    2016-05-01

    The water absorption in two aromatic linear polymers (PEEK and PEI) was studied between 10% and 90% RH at 30, 50 and 70°C. It was found that these polymers display classical Henry and Fick's behaviors. Moreover, they have very close values of equilibrium water concentration C∞ and water diffusivity D presumably because their respective polar groups establish molecular interactions of the same nature with water. This assumption was checked from a literature compilation of values of C∞ and D for a large variety of linear and tridimensional polymers containing a single type of polar group. It was then evidenced that almost all types of carbonyl group (in particular, those belonging to imides, amides and ketones) have the same molar contribution to water absorption, except those belonging to esters which are much less hydrophilic. Furthermore, hydroxyl and sulfone groups are much more hydrophilic than carbonyl groups so that their molar contribution is located on another master curve. On this basis, semi-empirical structure/water transport property relationships were proposed. It was found that C∞ increases exponentially with the concentration of polar groups (presumably because water is doubly bonded), but also with the intensity of their molecular interactions with water. In contrast, D is inversely proportional to C∞, which means that polar group-water interactions slow down the rate of water diffusion.

  1. Measuring Multivalent Binding Interactions by Isothermal Titration Calorimetry.

    Science.gov (United States)

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

    2016-01-01

    Multivalent glycoconjugate-protein interactions are central to many important biological processes. Isothermal titration calorimetry (ITC) can potentially reveal the molecular and thermodynamic basis of such interactions. However, calorimetric investigation of multivalency is challenging. Binding of multivalent glycoconjugates to proteins (lectins) often leads to a stoichiometry-dependent precipitation process due to noncovalent cross-linking between the reactants. Precipitation during ITC titration severely affects the quality of the baseline as well as the signals. Hence, the resulting thermodynamic data are not dependable. We have made some modifications to address this problem and successfully studied multivalent glycoconjugate binding to lectins. We have also modified the Hill plot equation to analyze high quality ITC raw data obtained from multivalent binding. As described in this chapter, ITC-driven thermodynamic parameters and Hill plot analysis of ITC raw data can provide valuable information about the molecular mechanism of multivalent lectin-glycoconjugate interactions. The methods described herein revealed (i) the importance of functional valence of multivalent glycoconjugates, (ii) that favorable entropic effects contribute to the enhanced affinities associated with multivalent binding, (iii) that with the progression of lectin binding, the microscopic affinities of the glycan epitopes of a multivalent glycoconjugate decrease (negative cooperativity), (iv) that lectin binding to multivalent glycoconjugates, especially to mucins, involves internal diffusion jumps, (bind and jump) and (v) that scaffolds of glycoconjugates influence their entropy of binding. © 2016 Elsevier Inc. All rights reserved.

  2. Electrochemical sensors and devices for heavy metals assay in water: the French groups' contribution

    Directory of Open Access Journals (Sweden)

    Luca ePUJOL

    2014-04-01

    Full Text Available A great challenge in the area of heavy metal trace detection is the development of electrochemical techniques and devices which are user-friendly, robust, selective, with low detection limits and allowing fast analyses. This review presents the major contribution of the French scientific academic community in the field of electrochemical sensors and electroanalytical methods within the last 20 years. From the well-known polarography to the up-to-date generation of functionalized interfaces, the different strategies dedicated to analytical performances improvement are exposed: stripping voltammetry, solid mercury-free electrode, ion selective sensor, carbon based materials, chemically modified electrodes, nano-structured surfaces. The paper particularly emphasizes their advantages and limits face to the last Water Frame Directive devoted to the Environmental Quality Standards for heavy metals. Recent trends on trace metal speciation as well as on automatic on line monitoring devices are also evoked.

  3. A titration model for evaluating calcium hydroxide removal techniques

    Directory of Open Access Journals (Sweden)

    Mark PHILLIPS

    2015-02-01

    Full Text Available Objective Calcium hydroxide (Ca(OH2 has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH2 left after different endodontic irrigation methods. Material and Methods Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH2 for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH2 recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH2 followed by gross Ca(OH2 removal using hand files and randomized treatment of either: 1 Syringe irrigation; 2 Syringe irrigation with use of an apical file; 3 Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI, or 4 Syringe irrigation with apical file and PUI (n=12/group. Residual Ca(OH2 was dissolved with glycerin and titrated to measure residual Ca(OH2 left in the root. Results No method completely removed all residual Ca(OH2. The addition of 30 s PUI with or without apical file use removed Ca(OH2 significantly better than irrigation alone. Conclusions This technique allowed quantification of residual Ca(OH2. The use of PUI (with or without apical file resulted in significantly lower Ca(OH2 residue compared to irrigation alone.

  4. Estimation of Formation Enthalpies of Organic Pollutants from a New Structural Group Contribution Method

    Institute of Scientific and Technical Information of China (English)

    Mehdi Bagheri; Afshin Bakhtiari; Masoume Jaberi

    2013-01-01

    Chemical stability and reactivity of organic pollutants is dependent to their formation enthalpies.The main objective of this study is to provide simple straightforward strategy for prediction of the formation enthalpies of wide range organic pollutants only from their structural functional groups.Using such an extended dataset comprising 1694 organic chemicals from 77 diverse material classes benefits the generalizability and reliability of the study.The new suggested collection of 12 functional groups and a simple linear regression lead to promising statistics of R2=0.958,Q2Loo =0.956,and δAEE=57 kJ·mol-1 for the whole dataset.Moreover,unknown experimental formation enthalpies for 27 organic pollutants are estimated by the presented approach.The resultant model needs no technical software/calculations,and thus can be easily applied by a non-specialist user.

  5. Energy contribution of NOVA food groups and sociodemographic determinants of ultra-processed food consumption in the Mexican population.

    Science.gov (United States)

    Marrón-Ponce, Joaquín A; Sánchez-Pimienta, Tania G; Louzada, Maria Laura da Costa; Batis, Carolina

    2017-09-22

    To identify the energy contributions of NOVA food groups in the Mexican diet and the associations between individual sociodemographic characteristics and the energy contribution of ultra-processed foods (UPF). We classified foods and beverages reported in a 24 h recall according to the NOVA food framework into: (i) unprocessed or minimally processed foods; (ii) processed culinary ingredients; (iii) processed foods; and (iv) UPF. We estimated the energy contribution of each food group and ran a multiple linear regression to identify the associations between sociodemographic characteristics and UPF energy contribution. Mexican National Health and Nutrition Survey 2012. Individuals ≥1 years old (n 10 087). Unprocessed or minimally processed foods had the highest dietary energy contribution (54·0 % of energy), followed by UPF (29·8 %), processed culinary ingredients (10·2 %) and processed foods (6·0 %). The energy contribution of UPF was higher in: pre-school-aged children v. other age groups (3·8 to 12·5 percentage points difference (pp)); urban areas v. rural (5·6 pp); the Central and North regions v. the South (2·7 and 8·4 pp, respectively); medium and high socio-economic status v. low (4·5 pp, in both); and with higher head of household educational level v. without education (3·4 to 7·8 pp). In 2012, about 30 % of energy in the Mexican diet came from UPF. Our results showed that younger ages, urbanization, living in the North region, high socio-economic status and high head of household educational level are sociodemographic factors related to higher consumption of UPF in Mexico.

  6. Productive work groups in complex hospital units. Proposed contributions of the nurse executive.

    Science.gov (United States)

    Sheafor, M

    1991-05-01

    The Fiedler and Garcia cognitive resources contingency model of leadership offers a new approach for nurse executives to influence the productivity of work groups led by nurse managers. The author offers recommendations toward achieving the relatively stress-free environment for nurse managers specified by the model using Schmeiding's application of Orlando's communication theory to nursing administration. Suggestions for incorporating these insights into graduate education for nursing administration follow.

  7. Hydrogen Solubility in Heavy Undefined Petroleum Fractions Using Group Contributions Methods

    Directory of Open Access Journals (Sweden)

    Aguilar-Cisneros Humberto

    2017-01-01

    Full Text Available Hydrogen solubility in heavy undefined petroleum fractions is estimated by taking as starting point a method of characterization based on functional groups [ Carreón-Calderón et al. (2012 Ind. Eng. Chem. Res. 51, 14188-14198 ]. Such method provides properties entering into equations of states and molecular pseudostructures formed by non-integer numbers of functional groups. Using Vapor-Liquid Equilibria (VLE data from binary mixtures of known compounds, interaction parameters between hydrogen and the calculated functional groups were estimated. Besides, the incorporation of the hydrogen-carbon ratio of the undefined petroleum fractions into the method allows the corresponding hydrogen solubility to be properly estimated. This procedure was tested with seven undefined petroleum fractions from 27 to 6 API over wide ranges of pressure and temperature (323.15 to 623.15 K. The results seem to be in good agreement with experimental data (overall Relative Average Deviation, RAD < 15%.

  8. Common Mental Disorders among Occupational Groups: Contributions of the Latent Class Model

    Directory of Open Access Journals (Sweden)

    Kionna Oliveira Bernardes Santos

    2016-01-01

    Full Text Available Background. The Self-Reporting Questionnaire (SRQ-20 is widely used for evaluating common mental disorders. However, few studies have evaluated the SRQ-20 measurements performance in occupational groups. This study aimed to describe manifestation patterns of common mental disorders symptoms among workers populations, by using latent class analysis. Methods. Data derived from 9,959 Brazilian workers, obtained from four cross-sectional studies that used similar methodology, among groups of informal workers, teachers, healthcare workers, and urban workers. Common mental disorders were measured by using SRQ-20. Latent class analysis was performed on each database separately. Results. Three classes of symptoms were confirmed in the occupational categories investigated. In all studies, class I met better criteria for suspicion of common mental disorders. Class II discriminated workers with intermediate probability of answers to the items belonging to anxiety, sadness, and energy decrease that configure common mental disorders. Class III was composed of subgroups of workers with low probability to respond positively to questions for screening common mental disorders. Conclusions. Three patterns of symptoms of common mental disorders were identified in the occupational groups investigated, ranging from distinctive features to low probabilities of occurrence. The SRQ-20 measurements showed stability in capturing nonpsychotic symptoms.

  9. Application of sPC-SAFT and group contribution sPC-SAFT to polymer systems-Capabilities and limitations

    DEFF Research Database (Denmark)

    Tihic, Amra; von Solms, Nicolas; Michelsen, Michael Locht

    2009-01-01

    A group contribution (GC) version of the simplified Perturbed-Chain Statistical Associating Fluid Theory (sPC-SAFT) Equation of State is proposed in a previous work [A. Tihic, G.M. Kontogeorgis, N. von Solms, M.L. Michelsen, L Constantinou, Ind. Eng. Chem. Res. 47 (2008) 5092-5101]. The reported......PC-SAFT model, with and without GC. The reported results contribute to a better understanding of the applicability of the sPC-SAFT model to binary polymer mixtures, and identify both models as good predictive tools for several industrial applications. Limitations are also identified and discussed....

  10. Efficacy of split night CPAP titration in moderate and severe obstructive sleep apnea syndrome patients

    Directory of Open Access Journals (Sweden)

    Shereen Farghaly

    2016-01-01

    Conclusion: Split night sleep study is more commonly associated with unsuccessful CPAP titration than full night titration but successful titration could be obtained during split night titration in patients with severe AHI >36.5 event/h.

  11. New Group-Contribution Approach to Thermochemical Properties of Organic Compounds: Hydrocarbons and Oxygen-Containing Compounds

    Science.gov (United States)

    Verevkin, S. P.; Emel'yanenko, V. N.; Diky, V.; Muzny, C. D.; Chirico, R. D.; Frenkel, M.

    2013-09-01

    A new group-contribution approach involving systematic corrections for 1,4-non-bonded carbon-carbon and carbon-oxygen interactions has been proposed. Limits of the applicability of the method, associated with the highly branched structures, were established. Experimental data for enthalpies of formation in the liquid phase, enthalpies of vaporization, and enthalpies of formation in the gas phase for alkanes, alkenes, alkynes, alkylbenzenes, alkanols, ethers, ketones and aldehydes, carboxylic acids, esters, and carbonates were collected and critically evaluated through dynamic data evaluation as implemented in the NIST ThermoData Engine. An automatic procedure for molecular structure "decomposition" was developed, and algorithms for the assessment of expanded uncertainties for the predicted property values were implemented. The combination of these software tools allows for ongoing improvements of the group-contribution parameter set as new experimental data become available. Fifty-two group-contribution parameters and their variances were evaluated for the proposed schema. Based on comparison of critically evaluated and predicted data for all classes of compounds studied, the performance of the new group formulation and associated parameters is superior to that originally suggested by Benson and the update by Cohen without an increase in the number of required parameters.

  12. Wetting by Liquid Metals—Application in Materials Processing: The Contribution of the Grenoble Group

    Directory of Open Access Journals (Sweden)

    Nicolas Eustathopoulos

    2015-03-01

    Full Text Available The wettability of ceramics by liquid metals is discussed from both the fundamental point of view and the point of view of applications. The role of interfacial reactions (simple dissolution of the solid in the liquid or formation of a layer of a new compound is illustrated and analysed. Several results are presented in order to illustrate the role of wettability in materials processing, namely infiltration processing, joining dissimilar materials by brazing and selecting crucibles for crystallising liquid metals and semiconductors. The review includes results obtained during the last 15 years mainly, but not only, by the Grenoble group.

  13. Hydrogen peroxide contributes to the epithelial cell death induced by the oral mitis group of streptococci.

    Directory of Open Access Journals (Sweden)

    Nobuo Okahashi

    Full Text Available Members of the mitis group of streptococci are normal inhabitants of the commensal flora of the oral cavity and upper respiratory tract of humans. Some mitis group species, such as Streptococcus oralis and Streptococcus sanguinis, are primary colonizers of the human oral cavity. Recently, we found that hydrogen peroxide (H2O2 produced by S. oralis is cytotoxic to human macrophages, suggesting that streptococcus-derived H2O2 may act as a cytotoxin. Since epithelial cells provide a physical barrier against pathogenic microbes, we investigated their susceptibility to infection by H2O2-producing streptococci in this study. Infection by S. oralis and S. sanguinis was found to stimulate cell death of Detroit 562, Calu-3 and HeLa epithelial cell lines at a multiplicity of infection greater than 100. Catalase, an enzyme that catalyzes the decomposition of H2O2, inhibited S. oralis cytotoxicity, and H2O2 alone was capable of eliciting epithelial cell death. Moreover, S. oralis mutants lacking the spxB gene encoding pyruvate oxidase, which are deficient in H2O2 production, exhibited reduced cytotoxicity toward Detroit 562 epithelial cells. In addition, enzyme-linked immunosorbent assays revealed that both S. oralis and H2O2 induced interleukin-6 production in Detroit 562 epithelial cells. These results suggest that streptococcal H2O2 is cytotoxic to epithelial cells, and promotes bacterial evasion of the host defense systems in the oral cavity and upper respiratory tracts.

  14. Group contribution methodology based on the statistical associating fluid theory for heteronuclear molecules formed from Mie segments.

    Science.gov (United States)

    Papaioannou, Vasileios; Lafitte, Thomas; Avendaño, Carlos; Adjiman, Claire S; Jackson, George; Müller, Erich A; Galindo, Amparo

    2014-02-07

    A generalization of the recent version of the statistical associating fluid theory for variable range Mie potentials [Lafitte et al., J. Chem. Phys. 139, 154504 (2013)] is formulated within the framework of a group contribution approach (SAFT-γ Mie). Molecules are represented as comprising distinct functional (chemical) groups based on a fused heteronuclear molecular model, where the interactions between segments are described with the Mie (generalized Lennard-Jonesium) potential of variable attractive and repulsive range. A key feature of the new theory is the accurate description of the monomeric group-group interactions by application of a high-temperature perturbation expansion up to third order. The capabilities of the SAFT-γ Mie approach are exemplified by studying the thermodynamic properties of two chemical families, the n-alkanes and the n-alkyl esters, by developing parameters for the methyl, methylene, and carboxylate functional groups (CH3, CH2, and COO). The approach is shown to describe accurately the fluid-phase behavior of the compounds considered with absolute average deviations of 1.20% and 0.42% for the vapor pressure and saturated liquid density, respectively, which represents a clear improvement over other existing SAFT-based group contribution approaches. The use of Mie potentials to describe the group-group interaction is shown to allow accurate simultaneous descriptions of the fluid-phase behavior and second-order thermodynamic derivative properties of the pure fluids based on a single set of group parameters. Furthermore, the application of the perturbation expansion to third order for the description of the reference monomeric fluid improves the predictions of the theory for the fluid-phase behavior of pure components in the near-critical region. The predictive capabilities of the approach stem from its formulation within a group-contribution formalism: predictions of the fluid-phase behavior and thermodynamic derivative properties of

  15. Thermochemical properties and contribution groups for ketene dimers and related structures from theoretical calculations.

    Science.gov (United States)

    Morales, Giovanni; Martínez, Ramiro

    2009-07-30

    This research's main goals were to analyze ketene dimers' relative stability and expand group additivity value (GAV) methodology for estimating the thermochemical properties of high-weight ketene polymers (up to tetramers). The CBS-Q multilevel procedure and statistical thermodynamics were used for calculating the thermochemical properties of 20 cyclic structures, such as diketenes, cyclobutane-1,3-diones, cyclobut-2-enones and pyran-4-ones, as well as 57 acyclic base compounds organized into five groups. According to theoretical heat of formation predictions, diketene was found to be thermodynamically favored over cyclobutane-1,3-dione and its enol-tautomeric form (3-hydroxycyclobut-2-enone). This result did not agree with old combustion experiments. 3-Hydroxycyclobut-2-enone was found to be the least stable dimer and its reported experimental detection in solution may have been due to solvent effects. Substituted diketenes had lower stability than substituted cyclobutane-1,3-diones with an increased number of methyl substituents, suggesting that cyclobutane-1,3-dione type dimers are the major products because of thermodynamic control of alkylketene dimerization. Missing GAVs for the ketene dimers and related structures were calculated through linear regression on the 57 acyclic base compounds. Corrections for non next neighbor interactions (such as gauche, eclipses, and internal hydrogen bond) were needed for obtaining a highly accurate and precise regression model. To the best of our knowledge, the hydrogen bond correction for GAV methodology is the first reported in the literature; this correction was correlated to MP2/6-31Gdagger and HF/6-31Gdagger derived geometries to facilitate its application. GAVs assessed by the linear regression model were able to reproduce acyclic compounds' theoretical thermochemical properties and experimental heat of formation for acetylacetone. Ring formation and substituent position corrections were calculated by consecutively

  16. Seismic structure beneath the Gulf of California: a contribution from group velocity measurements

    Science.gov (United States)

    Di Luccio, F.; Persaud, P.; Clayton, R. W.

    2014-12-01

    Rayleigh wave group velocity dispersion measurements from local and regional earthquakes are used to interpret the lithospheric structure in the Gulf of California region. We compute group velocity maps for Rayleigh waves from 10 to 150 s using earthquakes recorded by broad-band stations of the Network of Autonomously Recording Seismographs in Baja California and Mexico mainland, UNM in Mexico, BOR, DPP and GOR in southern California and TUC in Arizona. The study area is gridded in 120 longitude cells by 180 latitude cells, with an equal spacing of 10 × 10 km. Assuming that each gridpoint is laterally homogeneous, for each period the tomographic maps are inverted to produce a 3-D lithospheric shear wave velocity model for the region. Near the Gulf of California rift axis, we found three prominent low shear wave velocity regions, which are associated with mantle upwelling near the Cerro Prieto volcanic field, the Ballenas Transform Fault and the East Pacific Rise. Upwelling of the mantle at lithospheric and asthenospheric depths characterizes most of the Gulf. This more detailed finding is new when compared to previous surface wave studies in the region. A low-velocity zone in northcentral Baja at ˜28ºN which extends east-south-eastwards is interpreted as an asthenospheric window. In addition, we also identify a well-defined high-velocity zone in the upper mantle beneath central-western Baja California, which correlates with the previously interpreted location of the stalled Guadalupe and Magdalena microplates. We interpret locations of the fossil slab and slab window in light of the distribution of unique post-subduction volcanic rocks in the Gulf of California and Baja California. We also observe a high-velocity anomaly at 50-km depth extending down to ˜130 km near the southwestern Baja coastline and beneath Baja, which may represent another remnant of the Farallon slab.

  17. The Origin and Advancement of Cardiovascular Physiology in Brazil: The contribution of Eduardo Krieger to research groups

    Directory of Open Access Journals (Sweden)

    Elisardo C Vasquez

    2016-04-01

    Full Text Available Since 1996, symposia devoted to the discussion of advances in cardiovascular physiology have been alternately organized by Brazilian research groups, most of which were created or joined by PhD trainees of Eduardo M Krieger. Therefore, as Frontiers in Physiology is publishing a topic devoted to the celebration of the 20th edition of the Brazilian Symposium of Cardiovascular Physiology, it is a great opportunity to talk about the contributions of Eduardo Krieger to the development of cardiovascular physiology. In this historical mini-review, first, the influence of the Argentinean group of Bernardo Houssay and Braun Menéndez on cardiovascular physiology in Brazil is discussed. Second, the contribution of Eduardo Krieger to the creation of several of those groups and to the development of science and technology is reviewed. Finally, the origin and consolidation of the group of Vitoria is highlighted as an example of a research group that was influenced by the University of Sao Paulo-Faculty of Medicine of Ribeirao Preto and has trained hundreds of Master and PhD students in the area of cardiovascular research.

  18. The Origin and Advancement of Cardiovascular Physiology in Brazil: The Contribution of Eduardo Krieger to Research Groups.

    Science.gov (United States)

    Vasquez, Elisardo C

    2016-01-01

    Since 1996, symposia devoted to the discussion of advances in cardiovascular physiology have been alternately organized by Brazilian research groups, most of which were created or joined by Ph.D. trainees of Eduardo M Krieger. Therefore, as Frontiers in Physiology is publishing a topic devoted to the celebration of the 20th edition of the Brazilian Symposium of Cardiovascular Physiology, it is a great opportunity to talk about the contributions of Eduardo Krieger to the development of cardiovascular physiology. In this historical mini-review, first, the influence of the Argentinian group of Bernardo Houssay and Braun Menéndez on cardiovascular physiology in Brazil is discussed. Second, the contribution of Eduardo Krieger to the creation of several of those groups and to the development of science and technology is reviewed. Finally, the origin and consolidation of the group of Vitoria is highlighted as an example of a research group that was influenced by the University of Sao Paulo-Faculty of Medicine of Ribeirao Preto and has trained hundreds of Master and Ph.D. students in the area of cardiovascular research.

  19. Group A Streptococcal Cysteine Protease Cleaves Epithelial Junctions and Contributes to Bacterial Translocation*

    Science.gov (United States)

    Sumitomo, Tomoko; Nakata, Masanobu; Higashino, Miharu; Terao, Yutaka; Kawabata, Shigetada

    2013-01-01

    Group A Streptococcus (GAS) is an important human pathogen that possesses an ability to translocate across the epithelial barrier. In this study, culture supernatants of tested GAS strains showed proteolytic activity against human occludin and E-cadherin. Utilizing various types of protease inhibitors and amino acid sequence analysis, we identified SpeB (streptococcal pyrogenic exotoxin B) as the proteolytic factor that cleaves E-cadherin in the region neighboring the calcium-binding sites within the extracellular domain. The cleaving activities of culture supernatants from several GAS isolates were correlated with the amount of active SpeB, whereas culture supernatants from an speB mutant showed no such activities. Of note, the wild type strain efficiently translocated across the epithelial monolayer along with cleavage of occludin and E-cadherin, whereas deletion of the speB gene compromised those activities. Moreover, destabilization of the junctional proteins was apparently relieved in cells infected with the speB mutant, as compared with those infected with the wild type. Taken together, our findings indicate that the proteolytic efficacy of SpeB in junctional degradation allows GAS to invade deeper into tissues. PMID:23532847

  20. Outpatient titration of carbidopa/levodopa enteral suspension (Duopa).

    Science.gov (United States)

    Pahwa, Rajesh; Lyons, Kelly E

    2017-05-01

    Carbidopa/levodopa enteral suspension (CLES; Duopa) is a suspension or gel formulation of carbidopa/levodopa that is approved by the USA Food and Drug Administration for the treatment of advanced Parkinson's disease patients with motor fluctuations. CLES is delivered at a constant rate continuously throughout the day into the jejunum through an infusion pump via a PEG-J tube implanted surgically. The efficacy of CLES was established in the USA based on a randomized, double-blind, double-dummy, active controlled, parallel group and 12-week study, in which mean daily OFF time was reduced by 4.0 h, compared to 1.9 h with oral immediate release carbidopa/levodopa. The CLES hardware consists of a cassette containing the drug, a pump to deliver the drug and tubing to connect the PEG-J to the pump. It is critical to understand the appropriate conversion of the carbidopa/levodopa daily dosages to the CLES dosage and how to program the pump and titrate CLES to achieve the most effective dose. We describe one methodology for patient selection, outpatient titration and pump programming.

  1. Social support contributes to resilience among physiotherapy students: a cross sectional survey and focus group study.

    Science.gov (United States)

    Bíró, Éva; Veres-Balajti, Ilona; Kósa, Karolina

    2016-06-01

    The present study, taking a resource-oriented approach to mental health, aimed at investigating mental resilience and its determinants among undergraduate physiotherapy students using quantitative and qualitative tools. A questionnaire-based cross-sectional survey supplemented by 2 focus groups. One university in Hungary. 130 physiotherapy students at years 1, 2, and 3. Sense of coherence, a measure of dynamic self-esteem, as well as social support from family and peers were used to assess mental well-being. A screening instrument for psychological morbidity and perceived stress were used as deficiency-oriented approaches. Student opinions were gathered on positive and negative determinants of mental health. Resilience was lower [mean difference 4.8 (95% CI -3.4; 13.1)], and the occurrence of psychological morbidity (32.5% vs. 0%) was higher among female compared to male students. However, the proportion of students fully supported by their peers was higher among females (63% vs. 37.5%). Female students, unlike their male counterparts, experienced higher stress compared to their peers in the general population. Social support declined as students progressed in their studies though this proved to be the most important protective factor for their mental well-being. Results were fed back to the course organizers recommending the implementation of an evidence-based method to improve social support as delineated by the Guide to Community Preventive Services of the US the outcomes of which are to be seen in the future. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  2. pH titrations of molluscan paramyosin at two different ionic strengths.

    Science.gov (United States)

    Cooley, L B; Krause, S

    1980-11-01

    Paramyosin extracted from the adductor muscle of Mercenaria mercenaria, the chowder clam, was titrated both in 0.3 M KCl and in 1 mM KCl. Both the presumed native form of the molecule, acid-R-paramyosin, and a slightly degraded form, beta-paramyosin, were studied. Titrations of both types of paramyosin were similar in 1 mM k+, except that the native paramyosin is more highly charged at pH 3.2 than beta-paramyosin, as postulated previously (DeLaney and Krause, 1976, Macromolecules, 9:455), and that more groups titrate on the native molecule than on beta-paramyosin, both between pH 3.2 and 3.3 and between pH 3.2 and 10. Titrations in 0.30 M KCl, unlike those in 1 mM K, depended on starting pH; long term exposure to alkali solutions during dialysis, previously shown to cause partial dephosphorylation of paramyosin (Cooley et al., 1979, J. Biol. Chem., 254:2195), apparently also leads to a change in intermolecular interactions sufficient to cause changes in the titration curves in 0.30 M KCl but not in 1 mM K+.

  3. Continuous thermodynamics and group contribution methods for coal liquids: Final report, October 1, 1986--October 1, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Allen, D. T.; Behmanesh, N.; Vajdi, L. E.

    1989-01-01

    Structural profiles of narrow-boiling range fractions from three coal liquefaction processes were determined by identifying the major functional groups in the distillates and estimating their concentrations. The structural profiles were based on an extensive set of analytical data including results from elemental analysis, proton nuclear magnetic resonance, mass spectrometry, infrared spectroscopy and liquid chromatography. The functional group distributions were then interfaced with group contribution methods for property estimation. Heat capacities, critical constants, activity coefficients, hydrogen solubilities and vapor pressures were estimated for the narrow boiling fractions. The predictions have been compared to the predictions of more conventional property estimation methods and to experimental data. In addition, sensitivity analyses have been performed to determine which structural features in the coal derived liquids are most important in estimating the values of thermodynamic properties. 43 refs., 16 figs., 59 tabs.

  4. Proposition of group molar constants for sodium to calculate the partial solubility parameters of sodium salts using the van Krevelen group contribution method.

    Science.gov (United States)

    Barra, J; Peña, M A; Bustamante, P

    2000-04-01

    The aim of this study is to propose, for the first time, a set of group molar constants for sodium to calculate the partial solubility parameters of sodium salts. The values were estimated using the few experimental partial solubility parameters of acid/sodium salt series available either from the literature (benzoic acid/Na, ibuprofen acid/Na, diclofenac Na) or determined in this work (salicylic acid/Na, p-aminobenzoic acid/Na, diclofenac), the group contribution method of van Krevelen to calculate the partial parameters of the acids, and three reasonable hypothesis. The experimental method used is a modification of the extended Hansen approach based on a regression analysis of the solubility mole fraction of the drug lnX(2) against models including three- or four-partial solubility parameters of a series of pure solvents ranging from non-polar (heptane) to highly polar (water). The modified method combined with the four-parameter model provided the best results for both acids and sodium derivatives. The replacement of the acidic proton by sodium increased the dipolar and basic partial solubility parameters, whereas the dispersion parameter remained unaltered, thus increasing the overall total solubility parameter of the salt. The proposed group molar constants of sodium are consistent with the experimental results as sodium has a relatively low London dispersion molar constant (identical to that of -OH), a very high Keesom dipolar molar constant (identical to that of -NO(2), two times larger than that of -OH), and a very high hydrogen bonding molar constant (identical to that of -OH). The proposed values are: F((Na)d)=270 (J cm(3))(1/2) mol(-1); F((Na)p)=1030 (J cm(3))(1/2) mol(-1); U((Na)h)=17000 J mol(-1). Like the constants for the other groups, the group molar constants proposed for sodium are certainly not the exact values. However, they are believed to be a fair approximation of the impact of sodium on the partial solubility parameters and, therefore, can

  5. Titrated oral misoprostol solution compared with intravenous oxytocin for labor augmentation: a randomized controlled trial.

    Science.gov (United States)

    Ho, Ming; Cheng, Shi-Yann; Li, Tsai-Chung

    2010-09-01

    To compare titrated oral misoprostol to intravenous oxytocin for labor augmentation among women at 36 to 42 weeks of gestation with spontaneous onset of active labor. Women meeting the general selection criteria with regular contractions and an effaced cervix dilated between 3 and 9 cm, and who had inadequate uterine contractions (two or fewer contractions every 10 minutes) during the first stage of labor, were randomly assigned to titrated oral misoprostol or intravenous oxytocin. Augmentation-to-vaginal delivery interval and vaginal delivery within 12 or 24 hours were the primary outcomes. The data were analyzed by intention to treat. Of the 231 women, 118 (51.1%) were randomized to titrated oral misoprostol and 113 (48.9%) to titrated intravenous oxytocin. The median interval from the start of augmentation to vaginal delivery was 5.22 hours (3.77-8.58 hours, 25th-75th percentile) in the misoprostol group, and 5.20 hours (3.23-6.50 hours, 25th-75th percentile) in the intravenous oxytocin group (P=.019). Complete vaginal delivery occurred within 12 hours for 92 women (78.0%) in the misoprostol group and for 97 women (85.8%) in the oxytocin group (P=.121; relative risk 0.91, 95% confidence interval 0.80-1.03). There were no significant differences between the two groups who delivered vaginally within 24 hours. Side effects and neonatal outcomes also did not differ between the two groups. Labor augmentation with titrated oral misoprostol or intravenous oxytocin resulted in similar rates of vaginal delivery within 12 and 24 hours. ClinicalTrials.gov, www.clinicaltrials.gov, NCT00695331. I.

  6. A Systematic Methodology for Uncertainty Analysis of Group Contribution Based and Atom Connectivity Index Based Models for Estimation of Properties of Pure Components

    DEFF Research Database (Denmark)

    Hukkerikar, Amol; Sarup, Bent; Sin, Gürkan

    One of the most widely employed group contribution method for estimation of properties of pure components is the Marrero and Gani (MG) method. For the given component whose molecular structure is not completely described by any of the available groups, group contribution+ method (combined MG method...... and atomic connectivity index method) has been employed to create the missing groups and predict their contributions through the regressed contributions of connectivity indices. The objective of this work is to develop a systematic methodology to carry out uncertainty analysis of group contribution based...... and atom connectivity index based property prediction models. This includes: (i) parameter estimation using available MG based property prediction models and large training sets to determine improved group and atom contributions; and (ii) uncertainty analysis to establish statistical information...

  7. Group 1 LEA proteins contribute to the desiccation and freeze tolerance of Artemia franciscana embryos during diapause.

    Science.gov (United States)

    Toxopeus, Jantina; Warner, Alden H; MacRae, Thomas H

    2014-11-01

    Water loss either by desiccation or freezing causes multiple forms of cellular damage. The encysted embryos (cysts) of the crustacean Artemia franciscana have several molecular mechanisms to enable anhydrobiosis-life without water-during diapause. To better understand how cysts survive reduced hydration, group 1 late embryogenesis abundant (LEA) proteins, hydrophilic unstructured proteins that accumulate in the stress-tolerant cysts of A. franciscana, were knocked down using RNA interference (RNAi). Embryos lacking group 1 LEA proteins showed significantly lower survival than control embryos after desiccation and freezing, or freezing alone, demonstrating a role for group 1 LEA proteins in A. franciscana tolerance of low water conditions. In contrast, regardless of group 1 LEA protein presence, cysts responded similarly to hydrogen peroxide (H2O2) exposure, indicating little to no function for these proteins in diapause termination. This is the first in vivo study of group 1 LEA proteins in an animal and it contributes to the fundamental understanding of these proteins. Knowing how LEA proteins protect A. franciscana cysts from desiccation and freezing may have applied significance in aquaculture, where Artemia is an important feed source, and in the cryopreservation of cells for therapeutic applications.

  8. Increasing titration speed by using an end paint anticipator device

    OpenAIRE

    2001-01-01

    A simple device is described for use in any titrations with the objective of rapidly locating the vicinity of the end point of a titration. The device stores inside about 10% of a 10 mL titrand solution. The titration itself proceeds with rapid addition of titrant until the end point is passed. The anticipator device now starts to rotate, using a dc motor, which is turned on by a micro-computer. The solution stored in the device is mixed with the already titrated solution and the property bei...

  9. Prediction of vapor pressure and heats of vaporization of edible oil/fat compounds by group contribution

    DEFF Research Database (Denmark)

    Ceriani, Roberta; Gani, Rafiqul; Liu, Y.A.

    2013-01-01

    databank (2036 values) composed by fatty compounds, i.e., fatty acids, methyl-, ethyl-, propyl- and butyl- esters, fatty alcohols, tri-, di- and monoacylglycerols and hydrocarbons. This new methodology gives improved predictions when compared to a prior group contribution equation (Ceriani and Meirelles......, 2004) due to the inclusion of new experimental data for fatty esters and partial acylglycerols (besides hydrocarbons) and critical points, and a new temperature dependency. Heats of vaporization are properly described as a function of reduced temperature up to the critical condition....

  10. Isothermal Titration Calorimetry to Characterize Enzymatic Reactions.

    Science.gov (United States)

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2016-01-01

    Isothermal titration calorimetry (ITC) is a technique that measures the heat released or absorbed during a chemical reaction as an intrinsic probe to characterize any chemical process that involves heat changes spontaneously occurring during the reaction. The general features of this method to determine the kinetic and thermodynamic parameters of enzymatic reactions (kcat, KM, ΔH) are described and discussed here together with some detailed applications to specific cases. ITC does not require any modification or labeling of the system under analysis, can be performed in solution, and needs only small amounts of enzyme. These properties make ITC an invaluable, powerful, and unique tool to extend the knowledge of enzyme kinetics to drug discovery. © 2016 Elsevier Inc. All rights reserved.

  11. Isothermal Titration Calorimetry of Chiral Polymeric Nanoparticles.

    Science.gov (United States)

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

    2015-09-01

    Chiral polymeric nanoparticles are of prime importance, mainly due to their enantioselective potential, for many applications such as catalysis and chiral separation in chromatography. In this article we report on the preparation of chiral polymeric nanoparticles by miniemulsion polymerization. In addition, we describe the use of isothermal titration calorimetry (ITC) to measure the chiral interactions and the energetics of the adsorption of enantiomers from aqueous solutions onto chiral polymeric nanoparticles. The characterization of chirality in nano-systems is a very challenging task; here, we demonstrate that ITC can be used to accurately determine the thermodynamic parameters associated with the chiral interactions of nanoparticles. The use of ITC to measure the energetics of chiral interactions and recognition at the surfaces of chiral nanoparticles can be applied to other nanoscale chiral systems and can provide further insight into the chiral discrimination processes of nanomaterials. © 2015 Wiley Periodicals, Inc.

  12. Contribution of ethnic group and socioeconomic status to degree of disability in rheumatoid arthritis in Chilean patients.

    Science.gov (United States)

    Alarcón, Ana M; Muñoz, Sergio; Kaufman, Jay S; Martínez, Carlos; Riedemann, Pablo; Kaliski, Sonia

    2015-04-01

    The aim of this study was to estimate the contributions of ethnic group and socioeconomic status as social determinants related to disability and disease activity in Chilean Mapuche and non-Mapuche patients with rheumatoid arthritis (RA). Descriptive cross-sectional study with a stratified hospital-based sample of 189 patients in treatment with disease-modifying anti-rheumatic drugs. We assessed disability as categorical variable with the Health Assessment Questionnaire, disease activity with the Disease Activity Score instrument, and socioeconomic status with a standard questionnaire used by the Chilean government. Measures of association, stratified analyses and a multiple logistic regression model were used to analyze the data using the Stata 12.1 software package. Low socioeconomic status (annual income below US$ 7,200) is associated with disability (OR 3.87 CI 1.68-9.20) and Mapuche ethnic identity also contributes to disability (OR 2.48, CI 1.09-5.89). Relevant but not statistically significant in multivariable models were variables such as age, gender and place of residence. RA patients with a low socioeconomic status have almost three times the odds of having a moderate to high disability, independent of their ethnic group, gender or place of residence. Therefore, healthcare efforts should be aimed at promoting early diagnosis and prompt treatment among populations with high levels of poverty, which in the region of the Araucanía means primarily indigenous rural areas.

  13. Inclusive public participation in health: Policy, practice and theoretical contributions to promote the involvement of marginalised groups in healthcare.

    Science.gov (United States)

    de Freitas, Cláudia; Martin, Graham

    2015-06-01

    Migrants and ethnic minorities are under-represented in spaces created to give citizens voice in healthcare governance. Excluding minority groups from the health participatory sphere may weaken the transformative potential of public participation, (re)producing health inequities. Yet few studies have focused on what enables involvement of marginalised groups in participatory spaces. This paper addresses this issue, using the Participation Chain Model (PCM) as a conceptual framework, and drawing on a case study of user participation in a Dutch mental health advocacy project involving Cape Verdean migrants. Data collection entailed observation, documentary evidence and interviews with Cape Verdeans affected by psychosocial problems (n = 20) and institutional stakeholders (n = 30). We offer practice, policy and theoretical contributions. Practically, we highlight the importance of a proactive approach providing minorities and other marginalised groups with opportunities and incentives that attract, retain and enable them to build and release capacity through involvement. In policy terms, we suggest that both health authorities and civil society organisations have a role in creating 'hybrid' spaces that promote the substantive inclusion of marginalised groups in healthcare decision-making. Theoretically, we highlight shortcomings of PCM and its conceptualisation of users' resources, suggesting adaptations to improve its conceptual and practical utility. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Thermodynamic investigations of protein's behaviour with ionic liquids in aqueous medium studied by isothermal titration calorimetry.

    Science.gov (United States)

    Bharmoria, Pankaj; Kumar, Arvind

    2016-05-01

    While a number of reports appear on ionic liquids-proteins interactions, their thermodynamic behaviour using suitable technique like isothermal titration calorimetry is not systematically presented. Isothermal titration calorimetry (ITC) is a key technique which can directly measure the thermodynamic contribution of IL binding to protein, particularly the enthalpy, heat capacities and binding stoichiometry. Ionic liquids (ILs), owing to their unique and tunable physicochemical properties have been the central area of scientific research besides graphene in the last decade, and growing unabated. Their encounter with proteins in the biological system is inevitable considering their environmental discharge though most of them are recyclable for a number of cycles. In this article we will cover the thermodynamics of proteins upon interaction with ILs as osmolyte and surfactant. The up to date literature survey of IL-protein interactions using isothermal titration calorimetry will be discussed and parallel comparison with the results obtained for such studies with other techniques will be highlighted to demonstrate the accuracy of ITC technique. Net stability of proteins can be obtained from the difference in the free energy (ΔG) of the native (folded) and denatured (unfolded) state using the Gibbs-Helmholtz equation (ΔG=ΔH-TΔS). Isothermal titration calorimetry can directly measure the heat changes upon IL-protein interactions. Calculation of other thermodynamic parameters such as entropy, binding constant and free energy depends upon the proper fitting of the binding isotherms using various fitting models. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. A Closer Look at Acid-Base Olfactory Titrations

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.…

  18. The coulometric titration of acids and bases in dimethylsulfoxide media

    NARCIS (Netherlands)

    Bos, M.; IJpma, S.T.; Dahmen, E.A.M.F.

    1976-01-01

    The coulometric titration of 20–200 μeq of acids and bases in DMSO media is described. In the titration of bases, the electro-oxidation of hydrogen at a platinized platinum electrode is used as the source of protons. The conditions for 100 % current efficiency at this electrode are low current

  19. SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

    Science.gov (United States)

    Pankow, J. F.; Asher, W. E.

    2008-05-01

    The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure poL (atm) and enthalpy of vaporization Δ Hvap (kJ mol-1) of organic compounds as functions of temperature (T). For each compound i, the method assumes log10poL,i (T)=∑kνk,ibk(T) where νk,i is the number of groups of type k, and bk (T) is the contribution to log10poL,i (T) by each group of type k. A zeroeth group is included that uses b0 (T) with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary), aromatic amine, amide (primary, secondary, and tertiary), peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C-C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk (T) is assumed to follow b(T)=B1/T+B2+B3T+B4ln T. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions po L,i=fi (T) are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict poL values is examined using a test set of 184 compounds and a T range that is as wide as 273.15 to 393.15 K for some compounds. σFIT is defined as the average over all points of the absolute value of the difference between experimental and predicted values of log10poL,i (T). After consideration of σFIT for the test set, the initial basis set and test set compounds are combined, and the B coefficients re-optimized. For all compounds and temperatures, σFIT=0.34: on average, poL,i (T) values are predicted to within a factor of 2. Because d(log10 poL,i (T))d(1/T) is related to the enthalpy of vaporization ΔHvap,i, the fitted B provide

  20. Estimation of environment-related properties of chemicals for design of sustainable processes: Development of group-contribution+ (GC+) models and uncertainty analysis

    DEFF Research Database (Denmark)

    Hukkerikar, Amol; Kalakul, Sawitree; Sarup, Bent

    2012-01-01

    The aim of this work is to develop group-3 contribution+ (GC+)method (combined group-contribution (GC) method and atom connectivity index (CI)) based 15 property models to provide reliable estimations of environment-related properties of organic chemicals together with uncertainties of estimated...

  1. Estimation of Environment-Related Properties of Chemicals for Design of Sustainable Processes: Development of Group-Contribution+ (GC+) Property Models and Uncertainty Analysis

    Science.gov (United States)

    The aim of this work is to develop group-contribution+ (GC+) method (combined group-contribution (GC) method and atom connectivity index (CI) method) based property models to provide reliable estimations of environment-related properties of organic chemicals together with uncert...

  2. Application of isothermal titration calorimetry in bioinorganic chemistry.

    Science.gov (United States)

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

    2010-11-01

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

  3. SEARCHING FOR CFC’s AND HCFC’s ALTERNATIVES. Part I: A REFRIGERANT DESIGN STRATEGY USING GROUP CONTRIBUTION METHODS

    Directory of Open Access Journals (Sweden)

    Y KHETIB

    2000-12-01

    Full Text Available It is now well established that the chlorofluorocarbons (CFC’s, the hydrochlorofluorocarbons (HCFC’s and other chlororinated hydrocarbons which are compounds mostly used as refrigerants, are causing more damages than benefits to the environment and particularly to the ozone layer. Therefore one can see how important it is to search for substitutes to these compounds with desirable combination of physical properties to meet the needs of specific applications but, ultimately, with no harms to the environment. In this paper, although the bases of a computer-aided design of refrigerants (CADR method being developed are outlined, the main purpose still remains the demonstration of the great ability and importance of group contribution methods in the development of such techniques, particularly for predicting vapour-liquid equilibria and other thermodynamic properties like the enthalpy or entropy of generated systems, by the use of models like the UNIFAC.

  4. Group II muscle afferents probably contribute to the medium latency soleus stretch reflex during walking in humans

    DEFF Research Database (Denmark)

    Grey, Michael James; Ladouceur, Michel; Andersen, Jacob B.

    2001-01-01

    1. The objective of this study was to determine which afferents contribute to the medium latency response of the soleus stretch reflex resulting from an unexpected perturbation during human walking. 2. Fourteen healthy subjects walked on a treadmill at approximately 3.5 km h(-1) with the left ankle...... component (P = 0.004), whereas the medium latency component was unchanged (P = 0.437). 6. Two hours after the ingestion of tizanidine, an alpha(2)-adrenergic receptor agonist known to selectively depress the transmission in the group II afferent pathway, the medium latency reflex was strongly depressed (P...... = 0.007), whereas the short latency component was unchanged (P = 0.653). 7. An ankle block with lidocaine hydrochloride was performed to suppress the cutaneous afferents of the foot and ankle. Neither the short (P = 0.453) nor medium (P = 0.310) latency reflexes were changed. 8. Our results support...

  5. Analysis of the sorption properties of different soils using water vapour adsorption and potentiometric titration methods

    Science.gov (United States)

    Skic, Kamil; Boguta, Patrycja; Sokołowska, Zofia

    2016-07-01

    Parameters of specific surface area as well as surface charge were used to determine and compare sorption properties of soils with different physicochemical characteristics. The gravimetric method was used to obtain water vapour isotherms and then specific surface areas, whereas surface charge was estimated from potentiometric titration curves. The specific surface area varied from 12.55 to 132.69 m2 g-1 for Haplic Cambisol and Mollic Gleysol soil, respectively, and generally decreased with pH (R=0.835; α = 0.05) and when bulk density (R=-0.736; α = 0.05) as well as ash content (R=-0.751; α = 0.05) increased. In the case of surface charge, the values ranged from 63.00 to 844.67 μmol g-1 Haplic Fluvisol and Mollic Gleysol, respecively. Organic matter gave significant contributions to the specific surface area and cation exchange capacity due to the large surface area and numerous surface functional groups, containing adsorption sites for water vapour molecules and for ions. The values of cation exchange capacity and specific surface area correlated linearly at the level of R=0.985; α = 0.05.

  6. Accurate Three States Model for Amino Acids with Two Chemically Coupled Titrating Sites in Explicit Solvent Atomistic Constant pH Simulations and pKa Calculations.

    Science.gov (United States)

    Dobrev, Plamen; Donnini, Serena; Groenhof, Gerrit; Grubmüller, Helmut

    2017-01-10

    Correct protonation of titratable groups in biomolecules is crucial for their accurate description by molecular dynamics simulations. In the context of constant pH simulations, an additional protonation degree of freedom is introduced for each titratable site, allowing the protonation state to change dynamically with changing structure or electrostatics. Here, we extend previous approaches for an accurate description of chemically coupled titrating sites. A second reaction coordinate is used to switch between two tautomeric states of an amino acid with chemically coupled titratable sites, such as aspartate (Asp), glutamate (Glu), and histidine (His). To this aim, we test a scheme involving three protonation states. To facilitate charge neutrality as required for periodic boundary conditions and Particle Mesh Ewald (PME) electrostatics, titration of each respective amino acid is coupled to a "water" molecule that is charged in the opposite direction. Additionally, a force field modification for Amber99sb is introduced and tested for the description of carboxyl group protonation. Our three states model is tested by titration simulations of Asp, Glu, and His, yielding a good agreement, reproducing the correct geometry of the groups in their different protonation forms. We further show that the ion concentration change due to the neutralizing "water" molecules does not significantly affect the protonation free energies of the titratable groups, suggesting that the three states model provides a good description of biomolecular dynamics at constant pH.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-01

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

  8. Comparing characterization of functionalized multi-walled carbon nanotubes by potentiometric proton titration, NEXAFS, and XPS

    Institute of Scientific and Technical Information of China (English)

    Zhiteng Zhang; Lisa Pfefferle; Gary L. Haller

    2014-01-01

    Since the discovery of carbon nanotubes (CNT), this material has been recognized as an attractive catalyst support. CNT must be functionalized before use as a catalyst support and typically this involves oxidation. However, the functional group distribution on the CNT is very complex mixture of groups and varies with oxidation agent used. Here a simple acid-base titration is introduced to characterize the oxygen functionalized CNT. By comparing characterization with near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) for both at the C and O K-edges, it can be demonstrated that potentiometric proton titration can be a fast and quan-titative analysis for Brönsted acid functional groups on CNT.

  9. SIMPOL.1: a simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

    Directory of Open Access Journals (Sweden)

    J. F. Pankow

    2008-05-01

    Full Text Available The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure poL (atm and enthalpy of vaporization Δ Hvap (kJ mol-1 of organic compounds as functions of temperature (T. For each compound i, the method assumes log10poL,i (T=∑kνk,ibk(T where νk,i is the number of groups of type k, and bk (T is the contribution to log10poL,i (T by each group of type k. A zeroeth group is included that uses b0 (T with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary, aromatic amine, amide (primary, secondary, and tertiary, peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C–C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk (T is assumed to follow b(T=B1/T+B2+B3T+B4ln T. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions po L,i=fi (T are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict poL values is examined using a test set of 184 compounds and a T range that is as wide as 273

  10. Contribution of AmyA, an extracellular alpha-glucan degrading enzyme, to group A streptococcal host-pathogen interaction.

    Science.gov (United States)

    Shelburne, Samuel A; Keith, David B; Davenport, Michael T; Beres, Stephen B; Carroll, Ronan K; Musser, James M

    2009-10-01

    alpha-Glucans such as starch and glycogen are abundant in the human oropharynx, the main site of group A Streptococcus (GAS) infection. However, the role in pathogenesis of GAS extracellular alpha-glucan binding and degrading enzymes is unknown. The serotype M1 GAS genome encodes two extracellular proteins putatively involved in alpha-glucan binding and degradation; pulA encodes a cell wall anchored pullulanase and amyA encodes a freely secreted putative cyclomaltodextrin alpha-glucanotransferase. Genetic inactivation of amyA, but not pulA, abolished GAS alpha-glucan degradation. The DeltaamyA strain had a slower rate of translocation across human pharyngeal epithelial cells. Consistent with this finding, the DeltaamyA strain was less virulent following mouse mucosal challenge. Recombinant AmyA degraded alpha-glucans into beta-cyclomaltodextrins that reduced pharyngeal cell transepithelial resistance, providing a physiologic explanation for the observed transepithelial migration phenotype. Higher amyA transcript levels were present in serotype M1 GAS strains causing invasive infection compared with strains causing pharyngitis. GAS proliferation in a defined alpha-glucan-containing medium was dependent on the presence of human salivary alpha-amylase. These data delineate the molecular mechanisms by which alpha-glucan degradation contributes to GAS host-pathogen interaction, including how GAS uses human salivary alpha-amylase for its own metabolic benefit.

  11. Invited and contributed papers presented by the theory group at the joint Varenna-Lausanne international workshop `theory of fusion plasmas`

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    In this report eight invited and contributed papers of the theory group are included which were presented at joint Varenna-Lausanne international workshop on `theory of fusion plasmas`. (author) figs., tabs., refs.

  12. Analysis of the Purity of Cetrimide by Titrations

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Rasmussen, Claus/Dallerup; Nielsen, Hans/Boye

    2006-01-01

    The purity of cetrimide, trimethyl tetradecyl ammonium bromide (TTAB), that is an important preservative of many cosmetic and pharmaceutical products, was determined by three independent methods of titration. Traditionally, cetrimide was analysed by an assay method of the European Pharmacopoeia (Ph....... Eur.), which showed consistently a low purity of cetrimide with large standard deviations associated, however. A systematic 3% bias of the Ph. Eur. assay method was identified by comparing the result with results of two alternative methods of titration that exhibited high precision and high accuracy....... Titration by perchloric acid showed a 99.69 ± 0.05 % purity of cetrimide and titration by silver nitrate showed a 99.85% ± 0.05 % purity while the traditional assay method predicted a purity of only 97.1 ± 0.4. It was found that the discrepancy could be identified as differences in selectivity during...

  13. A microcomputer-controlled system for titration analysis

    NARCIS (Netherlands)

    Boelema, Gerrit Jan

    1982-01-01

    This thesis deals with the results of the implementation of microprocessor technology in automatic titration equipment to obtain a versatile system for pharmaceutical, chemical analytical and optimization research purposes. ... Zie: Summary

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

    Science.gov (United States)

    Hodder, A. P. W.

    1983-01-01

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

  15. Titrated oral misoprostol solution- a new method of labour induction ...

    African Journals Online (AJOL)

    Titrated oral misoprostol solution- a new method of labour induction. ... a cheap, stable, orally active prostaglandin analogue, is effective for labour induction ... misoprostol doses commencing with 20 μg, increased after three doses to 40 μg.

  16. Complexometric Titration of Zinc: An Analytical Chemistry Laboratory Experiment

    Science.gov (United States)

    Novick, S. G.

    1997-12-01

    Complexometric titrations with EDTA have traditionally been performed in undergraduate analytical chemistry courses to determine the calcium or magnesium content of water. These titrations are performed at a basic pH, where the formation constants of Ca-EDTA and Mg-EDTA complexes are high. These types of problems are well-treated in the analytical chemistry textbooks. In contrast, treatment of metal ions whose EDTA complexes occur significantly at low pH (e.g., Zn2+, Fe3+, Cu2+, Ni2+, Pb2+, Al3+) is sparse. An incorrect conclusion can be reached by the student that practical EDTA titrations are only performed at high pH. In addition, widening the window of possible metal ions for complexometric titration affords the possibility of analyzing real world products, such as the cold lozenges discussed in the article.

  17. Microscope Titration and Extraction of DNA from Liver.

    Science.gov (United States)

    Mayo, Lois T.; And Others

    1993-01-01

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

  18. Microscope Titration and Extraction of DNA from Liver.

    Science.gov (United States)

    Mayo, Lois T.; And Others

    1993-01-01

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

  19. Depression may reduce adherence during CPAP titration trial

    National Research Council Canada - National Science Library

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

    2014-01-01

    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...

  20. Titration microcalorimetry of adsorption processes in aqueous systems

    NARCIS (Netherlands)

    Blandamer, Michael J.; Briggs, Barbara; Cullis, Paul M.; Irlam, Keith D.; Engberts, Jan B.F.N.; Kevelam, Jan

    1998-01-01

    Procedures are described for analysing enthalpograms characterising adsorption by macromolecules in solution recorded using a titration microcalorimeter. The experimental procedure involves injecting small aliquots of a solution containing adsorbate into a sample cell containing a solution of macrom

  1. Estimation of Environment-Related Properties of Chemicals for Design of Sustainable Processes: Development of Group-Contribution(+) (GC(+)) Property Models and Uncertainty Analysis

    OpenAIRE

    Hukkerikar, Amol; Kalakul, Sawitree; Sarup, Bent; Young, Douglas M.; Sin, Gürkan; Gani, Rafiqul

    2012-01-01

    The aim of this work is to develop group-3 contribution+ (GC+)method (combined group-contribution (GC) method and atom connectivity index (CI)) based 15 property models to provide reliable estimations of environment-related properties of organic chemicals together with uncertainties of estimated property values. For this purpose, a systematic methodology for property modeling and uncertainty analysis is used. The methodology includes a parameter estimation step to determine parameters of pro...

  2. Water mediated ligand functional group cooperativity: the contribution of a methyl group to binding affinity is enhanced by a COO(-) group through changes in the structure and thermodynamics of the hydration waters of ligand-thermolysin complexes.

    Science.gov (United States)

    Nasief, Nader N; Tan, Hongwei; Kong, Jing; Hangauer, David

    2012-10-11

    Ligand functional groups can modulate the contributions of one another to the ligand-protein binding thermodynamics, producing either positive or negative cooperativity. Data presented for four thermolysin phosphonamidate inhibitors demonstrate that the differential binding free energy and enthalpy caused by replacement of a H with a Me group, which binds in the well-hydrated S2' pocket, are more favorable in presence of a ligand carboxylate. The differential entropy is however less favorable. Dissection of these differential thermodynamic parameters, X-ray crystallography, and density-functional theory calculations suggest that these cooperativities are caused by variations in the thermodynamics of the complex hydration shell changes accompanying the H→Me replacement. Specifically, the COO(-) reduces both the enthalpic penalty and the entropic advantage of displacing water molecules from the S2' pocket and causes a subsequent acquisition of a more enthalpically, less entropically, favorable water network. This study contributes to understanding the important role water plays in ligand-protein binding.

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

    OpenAIRE

    1990-01-01

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

  4. SIMPOL.1: A simple group contribution method for predicting vapor pressures and enthalpies of vaporization of multifunctional organic compounds

    Directory of Open Access Journals (Sweden)

    J. F. Pankow

    2007-08-01

    Full Text Available The SIMPOL.1 group contribution method is developed for predicting the liquid vapor pressure pLo (atm and enthalpy of vaporization ΔHvap (kJ mol-1 of organic compounds as functions of temperature (T. For each compound i, the method assumes log10pL,io(T=Σkνk,ibk(T where νk,i is the number of groups of type k, and bk(T is the contribution to log10 pL,io(T by each group of type k. A zeroeth group is included that uses b0(T with ν0,i=1 for all i. A total of 30 structural groups are considered: molecular carbon, alkyl hydroxyl, aromatic hydroxyl, alkyl ether, alkyl ring ether, aromatic ether, aldehyde, ketone, carboxylic acid, ester, nitrate, nitro, alkyl amine (primary, secondary, and tertiary, aromatic amine, amide (primary, secondary, and tertiary, peroxide, hydroperoxide, peroxy acid, C=C, carbonylperoxynitrate, nitro-phenol, nitro-ester, aromatic rings, non-aromatic rings, C=C–C=O in a non-aromatic ring, and carbon on the acid-side of an amide. The T dependence in each of the bk(T is assumed to follow b(T=B1/T+B2+B3T+B4lnT. Values of the B coefficients are fit using an initial basis set of 272 compounds for which experimentally based functions pL,io=fi(T are available. The range of vapor pressure considered spans fourteen orders of magnitude. The ability of the initially fitted B coefficients to predict pLo values is examined using a test

  5. Bacterial histo-blood group antigens contributing to genotype-dependent removal of human noroviruses with a microfiltration membrane.

    Science.gov (United States)

    Amarasiri, Mohan; Hashiba, Satoshi; Miura, Takayuki; Nakagomi, Toyoko; Nakagomi, Osamu; Ishii, Satoshi; Okabe, Satoshi; Sano, Daisuke

    2016-05-15

    We demonstrated the genotype-dependent removal of human norovirus particles with a microfiltration (MF) membrane in the presence of bacteria bearing histo-blood group antigens (HBGAs). Three genotypes (GII.3, GII.4, and GII.6) of norovirus-like particles (NoVLPs) were mixed with three bacterial strains (Enterobacter sp. SENG-6, Escherichia coli O86:K61:B7, and Staphylococcus epidermidis), respectively, and the mixture was filtered with an MF membrane having a nominal pore size of 0.45 μm. All NoVLP genotypes were rejected by the MF membrane in the presence of Enterobacter sp. SENG-6, which excreted HBGAs as extracellular polymeric substances (EPS). This MF membrane removal of NoVLPs was not significant when EPS was removed from cells of Enterobacter sp. SENG-6. GII.6 NoVLP was not rejected with the MF membrane in the presence of E. coli O86:K61:B7, but the removal of EPS of E. coli O86:K61:B7 increased the removal efficiency due to the interaction of NoVLPs with the exposed B-antigen in lipopolysaccharide (LPS) of E. coli O86:K61:B7. No MF membrane removal of all three genotypes was observed when S. epidermidis, an HBGA-negative strain, was mixed with NoVLPs. These results demonstrate that the location of HBGAs on bacterial cells is an important factor in determining the genotype-dependent removal efficiency of norovirus particles with the MF membrane. The presence of HBGAs in mixed liquor suspended solids from a membrane bioreactor (MBR) pilot plant was confirmed by immune-transmission electron microscopy, which implies that bacterial HBGAs can contribute to the genotype-dependent removal of human noroviruses with MBR using MF membrane.

  6. Spinal high-mobility group box 1 contributes to mechanical allodynia in a rat model of bone cancer pain

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Wei [Department of Out-Patient, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Wang, Wei; Huang, Jing [Department of Anatomy and K. K. Leung Brain Research Centre, Fourth Military Medical University, Xi' an 710032 (China); Ren, Ning [Comprehensive Diagnostic and Therapeutic Center, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Wu, Sheng-Xi, E-mail: shengxi@fmmu.edu.cn [Department of Anatomy and K. K. Leung Brain Research Centre, Fourth Military Medical University, Xi' an 710032 (China); Li, Yong-Qi, E-mail: devneuro@fmmu.edu.cn [Comprehensive Diagnostic and Therapeutic Center, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China)

    2010-05-14

    Mechanisms underlying bone cancer-induced pain are largely unknown. Previous studies indicate that neuroinflammation in the spinal dorsal horn is especially involved. Being first reported as a nonhistone chromosomal protein, high-mobility group box 1 (HMGB1) is now implicated as a mediator of inflammation. We hypothesized that HMGB1 could trigger the release of cytokines in the spinal dorsal horn and contribute to bone cancer pain. To test this hypothesis, we first built a bone cancer pain model induced by intratibal injection of Walker 256 mammary gland carcinoma cells. The structural damage to the tibia was monitored by radiological analysis. The mechanical allodynia was measured and the expression of spinal HMGB1 and IL-1{beta} was evaluated. We observed that inoculation of cancer cells, but not heat-killed cells, induced progressive bone destruction from 9 d to 21 d post inoculation. Behavioral tests demonstrated that the significant nociceptive response in the cancer cells-injected rats emerged on day 9 and this kind of mechanical allodynia lasted at least 21 d following inoculation. Tumor cells inoculation significantly increased HMGB1 expression in the spinal dorsal horn, while intrathecal injecting a neutralizing antibody against HMGB1 showed an effective and reliable anti-allodynia effect with a dose-dependent manner. IL-1{beta} was significantly increased in caner pain rats while intrathecally administration of anti-HMGB1 could decrease IL-1{beta}. Together with previous reports, we predict that bone cancer induces HMGB1 production, enhancing spinal IL-1{beta} expression and thus modulating spinal excitatory synaptic transmission and pain response.

  7. Predicting proton titration in cationic micelle and bilayer environments

    Energy Technology Data Exchange (ETDEWEB)

    Morrow, Brian H.; Shen, Jana K. [Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201 (United States); Eike, David M.; Murch, Bruce P.; Koenig, Peter H. [Computational Chemistry, Modeling and Simulation GCO, Procter and Gamble, Cincinnati, Ohio 45201 (United States)

    2014-08-28

    Knowledge of the protonation behavior of pH-sensitive molecules in micelles and bilayers has significant implications in consumer product development and biomedical applications. However, the calculation of pK{sub a}’s in such environments proves challenging using traditional structure-based calculations. Here we apply all-atom constant pH molecular dynamics with explicit ions and titratable water to calculate the pK{sub a} of a fatty acid molecule in a micelle of dodecyl trimethylammonium chloride and liquid as well as gel-phase bilayers of diethyl ester dimethylammonium chloride. Interestingly, the pK{sub a} of the fatty acid in the gel bilayer is 5.4, 0.4 units lower than that in the analogous liquid bilayer or micelle, despite the fact that the protonated carboxylic group is significantly more desolvated in the gel bilayer. This work illustrates the capability of all-atom constant pH molecular dynamics in capturing the delicate balance in the free energies of desolvation and Coulombic interactions. It also shows the importance of the explicit treatment of ions in sampling the protonation states. The ability to model dynamics of pH-responsive substrates in a bilayer environment is useful for improving fabric care products as well as our understanding of the side effects of anti-inflammatory drugs.

  8. Titrated oral misoprostol for augmenting labour to improve maternal and neonatal outcomes.

    Science.gov (United States)

    Vogel, Joshua P; West, Helen M; Dowswell, Therese

    2013-09-23

    Labour dystocia is associated with a number of adverse maternal and neonatal outcomes. Augmentation of labour is a commonly used intervention in cases of labour dystocia. Misoprostol is an inexpensive and stable prostaglandin E1 analogue that can be administered orally, vaginally, sublingually or rectally. Misoprostol has proven to be effective at stimulating uterine contractions although it can have serious, and even life-threatening side-effects. Titration refers to the process of adjusting the dose, frequency, or both, of a medication on the basis of frequent review to achieve optimal outcomes. Studies have reported on a range of misoprostol titration regimens used for labour induction and titrated misoprostol may potentially be effective and safe for augmentation of labour. To examine the effects and safety of titrated oral misoprostol compared with placebo, oxytocin, other interventions, or no active treatment, in women with labour dystocia. The Trials Search Co-ordinator of the Cochrane Pregnancy and Childbirth Group searched the Cochrane Pregnancy and Childbirth Group's Trials Register; date of search: 29 May 2013. We also searched the reference lists of retrieved studies Randomised trials (including quasi-randomised and cluster-randomised trials) comparing titrated oral misoprostol with placebo, other interventions (e.g. oxytocin, other prostaglandins), or no treatment in women requiring augmentation of labour were eligible for inclusion. Two review authors independently assessed eligibility for inclusion, carried out data extraction and assessed risk of bias in included studies. Data were entered by one author and checked for accuracy. We included two randomised trials with a total of 581 women each comparing different regimens of titrated oral misoprostol with intravenous oxytocin. One study compared 20 mcg doses of misoprostol dissolved in water (repeated every hour up to four hours, after which the dose was increased to 40 mcg per hour up to a maximum

  9. Successful management of a difficult cancer pain patient by appropriate adjuvant and morphine titration

    Directory of Open Access Journals (Sweden)

    Shiv PS Rana

    2011-01-01

    Full Text Available Morphine has been used for many years to relieve cancer pain. Oral morphine (in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain. The dose of oral morphine is titrated up to achieve adequate relief from pain with minimal side effects. Antidepressant and anticonvulsant drugs, when used in addition to conventional analgesics, give excellent relief from cancer pain. Most cancer pain responds to pharmacological measures with oral morphine but some pain like neuropathic and bony pain, pain in children and elderly age group, and advanced malignancy pain are very difficult to treat. Here, we report the management of a similar patient of severe cancer pain and the difficulty that we came across during dose titration of oral morphine and adjuvant analgesic.

  10. Empiric Auto-Titrating CPAP in People with Suspected Obstructive Sleep Apnea

    Science.gov (United States)

    Drummond, Fitzgerald; Doelken, Peter; Ahmed, Qanta A.; Gilbert, Gregory E.; Strange, Charlie; Herpel, Laura; Frye, Michael D.

    2010-01-01

    Objective: Efficient diagnosis and treatment of obstructive sleep apnea (OSA) can be difficult because of time delays imposed by clinic visits and serial overnight polysomnography. In some cases, it may be desirable to initiate treatment for suspected OSA prior to polysomnography. Our objective was to compare the improvement of daytime sleepiness and sleep-related quality of life of patients with high clinical likelihood of having OSA who were randomly assigned to receive empiric auto-titrating continuous positive airway pressure (CPAP) while awaiting polysomnogram versus current usual care. Methods: Serial patients referred for overnight polysomnography who had high clinical likelihood of having OSA were randomly assigned to usual care or immediate initiation of auto-titrating CPAP. Epworth Sleepiness Scale (ESS) scores and the Functional Outcomes of Sleep Questionnaire (FOSQ) scores were obtained at baseline, 1 month after randomization, and again after initiation of fixed CPAP in control subjects and after the sleep study in auto-CPAP patients. Results: One hundred nine patients were randomized. Baseline demographics, daytime sleepiness, and sleep-related quality of life scores were similar between groups. One-month ESS and FOSQ scores were improved in the group empirically treated with auto-titrating CPAP. ESS scores improved in the first month by a mean of −3.2 (confidence interval −1.6 to −4.8, p auto-CPAP resulted in symptomatic improvement of daytime sleepiness and sleep-related quality of life in a cohort of patients awaiting polysomnography who had a high pretest probability of having OSA. Additional studies are needed to evaluate the applicability of empiric treatment to other populations. Citation: Drummond F; Doelken P; Ahmed QA; Gilbert GE; Strange C; Herpel L; Frye MD. Empiric auto-titrating CPAP in people with suspected obstructive sleep apnea. J Clin Sleep Med 2010;6(2):140-145. PMID:20411690

  11. A Comparative Study of Effectiveness of Peer Assessment of Individuals' Contributions to Group Projects in Undergraduate Construction Management Core Units

    Science.gov (United States)

    Jin, Xiao-Hua

    2012-01-01

    In recent years, various forms of group work have been introduced in university courses across various subject domains, including construction management courses. Although the use of group work in higher education has sound pedagogical reasons and advantages, group work has its own drawbacks. Therefore, the acceptance by students and the success…

  12. Making pH calculations in the titration of strong protolytes

    OpenAIRE

    2013-01-01

    Titration graphs of protolytic systems are very useful among other things to find the equivalence point (ep), choose the most suitable indicator, calculate the titration error and decide whether a given titration is feasible or not under certain conditions. The main feature of a titration curve is the pH jump that occurs in the vicinity of the equivalence point. Titration graphs can be obtained experimentally using the potentiometric method with the pH electrode. They also can be obtained the...

  13. Potentiometric titration and equivalent weight of humic acid

    Science.gov (United States)

    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.

  14. Intrinsic thermodynamics of 4-substituted-2,3,5,6-tetrafluorobenzenesulfonamide binding to carbonic anhydrases by isothermal titration calorimetry.

    Science.gov (United States)

    Zubrienė, Asta; Smirnovienė, Joana; Smirnov, Alexey; Morkūnaitė, Vaida; Michailovienė, Vilma; Jachno, Jelena; Juozapaitienė, Vaida; Norvaišas, Povilas; Manakova, Elena; Gražulis, Saulius; Matulis, Daumantas

    2015-10-01

    Para substituted tetrafluorobenzenesulfonamides bind to carbonic anhydrases (CAs) extremely tightly and exhibit some of the strongest known protein-small ligand interactions, reaching an intrinsic affinity of 2 pM as determined by displacement isothermal titration calorimetry (ITC). The enthalpy and entropy of binding to five CA isoforms were measured by ITC in two buffers of different protonation enthalpies. The pKa values of compound sulfonamide groups were measured potentiometrically and spectrophotometrically, and enthalpies of protonation were measured by ITC in order to evaluate the proton linkage contributions to the observed binding thermodynamics. Intrinsic means the affinity of a sulfonamide anion for the Zn bound water form of CAs. Fluorination of the benzene ring significantly enhanced the observed affinities as it increased the fraction of deprotonated ligand while having little impact on intrinsic affinities. Intrinsic enthalpy contributions to the binding affinity were dominant over entropy and were more exothermic for CA I than for other CA isoforms. Thermodynamic measurements together with the X-ray crystallographic structures of protein-ligand complexes enabled analysis of structure-activity relationships in this enzyme ligand system. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. [Dose-finding for treatment with a transdermal fentanyl patch : Titration with oral transmucosal fentanyl citrate and morphine sulfate].

    Science.gov (United States)

    Mücke, M; Conrad, R; Marinova, M; Cuhls, H; Elsner, F; Rolke, R; Radbruch, L

    2016-12-01

    To date, no studies investigating titration with oral transmucosal fentanyl for the dose-finding of transdermal fentanyl treatment have been published. In an open randomized study 60 patients with chronic malignant (n = 39) or nonmalignant pain (n = 21), who required opioid therapy according to step three of the guidelines of the World Health Organization (WHO), were investigated. In two groups of 30 patients each titration with immediate release morphine (IRM) or oral transmucosal fentanyl citrate (OTFC) was undertaken. For measurement purposes the Brief Pain Inventory (BPI) and Minimal Documentation System (MIDOS) were used. After a 24-h titration phase, in which patients documented the intensity of pain, nausea, and tiredness, treatment with transdermal fentanyl was evaluated over a 10-day period by means of the necessary dose adaptation (responder ≤ 1 dose adaptation; conversion formula 1:1 [OTFC group] vs 100:1 [IRM group]).The pain reduction over the first 24 h (titration phase) did not differ significantly between the groups. The number of responders (17 OTFC vs. 21 IRM) over the 10-day period did not show any difference either. In both groups there was a significant reduction in pain intensity (p IRM group (8 vs 1, p = 0.028).Oral transmucosal fentanyl citrate can be applied for the titration of transdermal fentanyl, but it does not show any clinically relevant advantage. For example, the risk of side effects-induced drop-outs was greater in the present study. Whether the unnecessary opioid switching to treat chronic pain and breakthrough pain is advantageous with regard to minimizing conversion errors cannot be definitively answered within the scope of this study.

  16. [Study on the inclusion behavior of p-sulphonatocalix[4]arene with acridine by spectrofluorometric titrations].

    Science.gov (United States)

    Zhou, Yun-You; Lu, Qin; Liu, Chun; She, Shi-Ke; Yang, Xu-Lai; Wang, Lun

    2006-09-01

    p-sulphonatocalix[4] arene (1) was prepared according to the literature, and spectrofluorometric titrations were performed to investigate the inclusion behavior of (1) and acridine in citrate buffer solution (pH 5.92, 0.1 mol x L(-1)) at different temperatures. It was found that in definite concentration range, the emission peak of acridine exhibited a slight red shift and th fluorescence intensity decreased when (1) was added. They form stable host-guest complex, and the stoichiometry of the inclusion complex is 1 : 1. The stability constants of the inclusion complex at 15.0 degrees C, 20.0, 25.0 and 30.0 degrees C were determined as 3.08 x 10(5), 4.45 x 10(4), 2.58 x 10(4) and 8.90 x 10(3), respectively. The thermodynamic parameters of inclusion process, deltaG, deltaH and deltaS, were determined. The experimental results indicated that the inclusion process was an exothermic and enthalpy-driven process. It was found that the stability constants descended when temperature rose. The most probable pattern of the inclusion complex between (1) and acridine was proposed as: acridine partially goes into the cavity of (1), and the protonated N atom and the negatively charged sulphonyl group bond firmly owing to strong electrostatic interaction. With the main contribution of electrostatic interaction and the assistance of Van de Waals and hydrophobic interaction, the host and the guest molecules form 1 : 1 supramolecular complex.

  17. Genetic and environmental contributions to population group differences on the Raven's Progressive Matrices estimated from twins reared together and apart

    OpenAIRE

    Rushton, J. Philippe; Bons, Trudy Ann; Vernon, Philip A; Čvorović, Jelena

    2007-01-01

    We carried out two studies to test the hypothesis that genetic and environmental influences explain population group differences in general mental ability just as they do individual differences within a group. We estimated the heritability and environmentality of scores on the diagrammatic puzzles of the Raven's Coloured and/or Standard Progressive Matrices (CPM/SPM) from two independent twin samples and correlated these estimates with group differences on the same items. In Study 1, 199 pair...

  18. The determination of titratable acidity and total tannins in red wine

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2009-01-01

    Full Text Available Titration acidity and content of total tannins in mass-market red wines are analyzed in this paper. The content of total acids in wine, expressed through wine acid, was analyzed by potentiometric titration on 7.00 pH value. According to titratable acidity in analyzed wines, all wines (only with analyzed parameters according to Regulations about wine quality. The analysis of differential potentiometric curves shows that these curves can give the answer to the question if non organic substances, amino groups and phenols are present in wine in large quantity, as they are always present in wine. However it doesn't give the clear answer which substances are present in analyzed samples. The answer to this question can be received only by the method of ionic chromatography. The content of total tannins shows short time of storage in wine cellars so wine wasn't stored long enough, i.e. they are commercial wines made for mass market production and consumption. Although they have less content of total tannin materials of given values, wine taste gives the correlation with other polyphenol materials that only give odour, aroma and 'bouquet' to wine. The relative error of mean value is very low which indicates the reproduction of results and reliability of the method of determination of total tannins in red wine.

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

    Science.gov (United States)

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

    2013-08-01

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

  20. Manufacturing of a Secretoneurin Drug Delivery System with Self-Assembled Protamine Nanoparticles by Titration

    Science.gov (United States)

    Scheicher, Bernhard; Lorenzer, Cornelia; Gegenbauer, Katrin; Partlic, Julia; Andreae, Fritz; Kirsch, Alexander H.; Rosenkranz, Alexander R.; Werzer, Oliver

    2016-01-01

    Since therapeutic peptides and oligonucleotides are gathering interests as active pharmaceutical ingredients (APIs), nanoparticulate drug delivery systems are becoming of great importance. Thereby, the possibility to design drug delivery systems according to the therapeutic needs of APIs enhances clinical implementation. Over the last years, the focus of our group was laid on protamine-oligonucleotide-nanoparticles (so called proticles), however, the possibility to modify the size, zeta potential or loading efficiencies was limited. Therefore, at the present study we integrated a stepwise addition of protamine (titration) into the formation process of proticles loaded with the angiogenic neuropeptide secretoneurin (SN). A particle size around 130 nm was determined when proticles were assembled by the commonly used protamine addition at once. Through application of the protamine titration process it was possible to modify and adjust the particle size between approx. 120 and 1200 nm (dependent on mass ratio) without influencing the SN loading capacity. Dynamic light scattering pointed out that the difference in particle size was most probably the result of a secondary aggregation. Initially-formed particles of early stages in the titration process aggregated towards bigger assemblies. Atomic-force-microscopy images also revealed differences in morphology along with different particle size. In contrast, the SN loading was only influenced by the applied mass ratio, where a slight saturation effect was observable. Up to 65% of deployed SN could be imbedded into the proticle matrix. An in-vivo biodistribution study (i.m.) showed a retarded distribution of SN from the site of injection after the application of a SN-proticle formulation. Further, it was demonstrated that SN loaded proticles can be successfully freeze-dried and resuspended afterwards. To conclude, the integration of the protamine titration process offers new possibilities for the formulation of proticles in

  1. Study of Complexes of Lanthanum with Amino Acids by Titration Calorimeter

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The stability constants and thermodynamic functions for complexes of lanthanum with eight kind of amino acids according to 1:1 and 1:2 in proportion have been determined by titration calorimeter at 298. 15 K. The enthalpy change makes a predominant contribution to the stability of these complexes. The ring in amino acid associated with lanthanum ion helps to enhance the stability of complexes. Steric effectsbetween rings in complexes leads to that the equilibrium constants of reaction of the complexes (1:2) ismuch less than that of the complexes (l:1).

  2. Titrated Misoprostol Versus Dinoprostone for Labor Induction

    African Journals Online (AJOL)

    Statistical analysis done using Student's t-test for quantitative data and ... Ahmadi Hospital, Kuwait Oil Company, .... Table 1: Demographic data, indication of induction of labor, and initial modified Bishop's score in both studied groups.

  3. The hadronic light-by-light contribution to the muon anomalous magnetic moment and renormalization group for EFT

    CERN Document Server

    Bijnens, Johan

    2012-01-01

    We give a short overview of the theory of the muon anomalous magnetic moment with emphasis on the hadronic light-by-light and the pion loop contribution. We explain the difference between the hidden local symmetry and full VMD pion loop and discuss leading logarithms in the anomalous sector of 2-flavour chiral perturbation theory.

  4. The hadronic light-by-light contribution to the muon anomalous magnetic moment and renormalization group for EFT

    Directory of Open Access Journals (Sweden)

    Abyaneh Mehran Zahiri

    2012-12-01

    Full Text Available We give a short overview of the theory of the muon anomalous magnetic moment with emphasis on the hadronic light-by-light and the pion loop contribution. We explain the difference between the hidden local symmetry and full VMD pion loop and discuss leading logarithms in the anomalous sector of 2-flavour chiral perturbation theory.

  5. Detection, Diagnosis and Prognosis: Contribution to the energy challenge: Proceedings of the Meeting of the Mechanical Failures Prevention Group

    Science.gov (United States)

    Shives, T. R. (Editor); Willard, W. A. (Editor)

    1981-01-01

    The contribution of failure detection, diagnosis and prognosis to the energy challenge is discussed. Areas of special emphasis included energy management, techniques for failure detection in energy related systems, improved prognostic techniques for energy related systems and opportunities for detection, diagnosis and prognosis in the energy field.

  6. Sex Does Not Matter: Gender Bias and Gender Differences in Peer Assessments of Contributions to Group Work

    Science.gov (United States)

    Tucker, Richard

    2014-01-01

    This paper considers the possibility of gender bias in peer ratings for contributions to team assignments, as measured by an online self-and-peer assessment tool. The research was conducted to determine whether peer assessment led to reliable and fair marking outcomes. The methodology of Falchikov and Magin was followed in order to test their…

  7. New applications of corrosion measurements by titration (CMT)

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1998-01-01

    CMT measurements and electrochemical (EC) measurements of corrosion rate are generally in agreement, when only electrochemical dissolution of metals in acid take place. However, dissolution of oxide layers and other acid-consuming reactions can cause CMT measurements to exceed EC measurements....... It is shown that when aluminium dissolves in alkali, CMT measurements can also be applied, but in this case requiring titration with alkali. Titration with alkali is also required in a special situation, where corrosion of nickel in an acid solution and subsequent formation of a nickel complex results...

  8. Fast coarse-grained model for RNA titration

    Science.gov (United States)

    Barroso da Silva, Fernando Luís; Derreumaux, Philippe; Pasquali, Samuela

    2017-01-01

    A new numerical scheme for RNA (ribonucleic acid) titration based on the Debye-Hückel framework for the salt description is proposed in an effort to reduce the computational costs for further applications to study protein-RNA systems. By means of different sets of Monte Carlo simulations, we demonstrated that this new scheme is able to correctly reproduce the experimental titration behavior and salt pKa shifts. In comparison with other theoretical approaches, similar or even better outcomes are achieved at much lower computational costs. The model was tested on the lead-dependent ribozyme, the branch-point helix, and the domain 5 from Azotobacter vinelandii Intron 5.

  9. Quantification of hydrolytic charge loss of DMAEA-Q-based polyelectrolytes by proton NMR spectroscopy and implications for colloid titration.

    Science.gov (United States)

    Saveyn, Hans; Hendrickx, Pieter M S; Dentel, Steven K; Martins, José C; Van der Meeren, Paul

    2008-05-01

    Copolymers of acrylamide and quaternised dimethylaminoethyl acrylate (DMAEA-Q) constitute an economically important range of cationic polyelectrolytes used in sludge conditioning. The latter treatment involves charge neutralisation and bridging induced by these polymers. Since both of these phenomena rely on charge-driven sorption onto the negatively charged colloidal particles, the accurate assessment of their charge density is of primary importance in polyelectrolyte characterisation. The experimental determination of this characteristic generally relies on colloidal charge titration, in which the cationic polymer is titrated against an anionic polymer. Hereby, one of the requirements to have a stoichiometric reaction between the oppositely charged polymers is a sufficiently low polymer concentration. In this study, it is shown that such a low polymer concentration may entail a pronounced hydrolysis effect for DMAEA-Q-based polymers, which leads to a release of the cationic side groups and hence causes considerable errors on the charge titration results. Proton nuclear magnetic resonance spectroscopy was applied to investigate the fast hydrolysis kinetics of DMAEA-Q polymers together with time-dependent charge titration measurements. Diffusion NMR spectroscopy was used to assist in establishing the nature of the hydrolysis compounds. The results from both techniques indicate that a high degree of hydrolysis is reached within minutes after dilution of a concentrated polymer stock solution into aqueous solutions of slightly acidic to neutral pH values. Therefore, a modification to the classic colloid titration procedure is proposed, using a buffered dilution liquid to avoid polymer hydrolysis. It is shown that a buffer pH value of 4.5 avoids not only polymer hydrolysis effects but also possible protonation of the anionic titrant, thereby avoiding overestimation of the charge density. By means of this procedure, reproducible and time-independent charge titration

  10. "Titration simulator"--Good assistant for titration analysis%滴定分析教学的好帮手"Titration simulator"

    Institute of Scientific and Technical Information of China (English)

    屠婕红

    2005-01-01

    @@ Titration simulator(滴定模拟器)软件是专门为滴定分析而设计的教学软件,它短小精悍,简洁实用,可以从Internet网上免费下载,网址为:http://www.chemonline.net/Truechemsoft/downsoft.asp?softID=1565该软件所占容量仅为72KB,是学生训练及化学教师的好助手.笔者在教学中尝试运用该软件辅助教学,效果良好,现将Titration simulator软件的主要功能、应用简要介绍如下:

  11. Trajectory and contribution of geoscientists (1906-1961) to dinosaur research in the Bauru Group (Cretaceous) in the Triângulo Mineiro region of Brazil

    Science.gov (United States)

    Peyerl, Drielli; Candeiro, Carlos Roberto A.; Mendonça Figueirôa, Silvia Fernanda

    2015-08-01

    The present study discusses geological and paleontological research conducted by geoscientists in the Late Cretaceous Bauru Group, of the Triângulo Mineiro region, Brazil. This analysis based largely on historical documentary sources focuses on the pioneering work of geoscientists, who made numerous discoveries of dinosaur fossils. This work contributes to a chronological survey that has been compiled on the geological studies in the Bauru Group, and describes the importance of the paleontological discoveries made during the twentieth century.

  12. Evaluation of the performance of a metrohm titrator titrando-836 in potentiometric analysis of uranium for safeguards purposes

    Energy Technology Data Exchange (ETDEWEB)

    Cristiano, Barbara Fernandes; Silva, Jose Wanderley S. da; Barros, Pedro Dionisio de; Araujo, Radier Mario S. de, E-mail: barbara@ird.gov.b, E-mail: wanderley@ird.gov.b, E-mail: pedrodio@ird.b, E-mail: radier@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RH (Brazil). Lab. de Salvaguardas

    2009-07-01

    To achieve the requirements of the Brazilian State System of Accounting for and Control of Nuclear Materials - SSAC the Safeguards Laboratory of Brazilian Nuclear Energy Commission, LASAL, has been applying the 'Davies and Gray/NBL' method for Potentiometric determination of total uranium concentration in several forms of nuclear materials since 1984. To improve the accuracy and the repeatability the method uses as titrant, standard reference potassium dichromate NIST SRM 136e and the results are also corrected for bias with NBL CRM 112A uranium metal assay standard. This work describes the assays performed for validation of a Metrohm 836 potentiometric titrator acquired by LASAL in order to improve the analytical methodology of the laboratory. The titrator is attached to a Pt:Rh (90:10) as indicator electrode and a mercurous sulfate as the reference electrode. The evaluation of accuracy and repeatability were made by comparison, the results provided by the titrator with the certified value of standards and also by the participation in round robin program sponsored by New Brunswick Laboratory - NBL. The validation was done by a comparison of the performance between the Metrohm 836 and a Mettler - DL67 titrator which has currently been used by the laboratory. It included evaluation of the results of both equipment, the repeatability of the measurement, any systematic contributions and its uncertainties. (author)

  13. A Conserved UDP-Glucose Dehydrogenase Encoded outside the hasABC Operon Contributes to Capsule Biogenesis in Group A Streptococcus

    NARCIS (Netherlands)

    Cole, Jason N.; Aziz, Ramy K.; Kuipers, Kirsten; Timmer, Anjuli M.; Nizet, Victor; van Sorge, Nina M.

    2012-01-01

    Group A Streptococcus (GAS) is a human-specific bacterial pathogen responsible for serious morbidity and mortality worldwide. The hyaluronic acid (HA) capsule of GAS is a major virulence factor, contributing to bloodstream survival through resistance to neutrophil and antimicrobial peptide killing a

  14. Genetic and environmental contributions to population group differences on the Raven's Progressive Matrices estimated from twins reared together and apart.

    Science.gov (United States)

    Rushton, J Philippe; Bons, Trudy Ann; Vernon, Philip A; Cvorović, Jelena

    2007-07-22

    We carried out two studies to test the hypothesis that genetic and environmental influences explain population group differences in general mental ability just as they do individual differences within a group. We estimated the heritability and environmentality of scores on the diagrammatic puzzles of the Raven's Coloured and/or Standard Progressive Matrices (CPM/SPM) from two independent twin samples and correlated these estimates with group differences on the same items. In Study 1, 199 pairs of 5- to 7-year-old monozygotic (MZ) and dizygotic (DZ) twins reared together provided estimates of heritability and environmentality for 36 puzzles from the CPM. These estimates correlated with the differences between the twins and 94 Serbian Roma (both rs=0.32; Ns=36; psadult MZ and DZ twins reared apart provided estimates of heritability and environmentality for 58 puzzles from the SPM. These estimates correlated with the differences among 11 diverse samples including (i) the reared-apart twins, (ii) another sample of Serbian Roma, and (iii) East Asian, White, South Asian, Coloured and Black high school and university students in South Africa. In 55 comparisons, group differences were more pronounced on the more heritable and on the more environmental items (mean rs=0.40 and 0.47, respectively; Ns=58; ps<0.05). After controlling for measurement reliability and variance in item pass rates, the heritabilities still correlated with the group differences, although the environmentalities did not. Puzzles found relatively difficult (or easy) by the twins were those found relatively difficult (or easy) by the others (mean r=0.87). These results suggest that population group differences are part of the normal variation expected within a universal human cognition.

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

    Energy Technology Data Exchange (ETDEWEB)

    Selig, W.S.

    1991-02-04

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

  16. Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

    Science.gov (United States)

    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…

  17. Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

    Science.gov (United States)

    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…

  18. Modeling of titration experiments by a reactive transport model

    Institute of Scientific and Technical Information of China (English)

    Ma Hongyun; Samper Javier; Xin Xin

    2011-01-01

    Acid mine drainage (AMD) is commonly treated by neutralization with alkaline substances. This treatment is supported by titration experiments that illustrate the buffering mechanisms and estimate the base neutralization capacity (BNC) of the AMD. Detailed explanation of titration curves requires modeling with a hydro-chemical model. In this study the titration curves of water samples from the drainage of the As Pontes mine and the corresponding dumps have been investigated and six buffers are selected by analyzing those curves. Titration curves have been simulated by a reactive transport model to discover the detailed buffering mechanisms. These simulations show seven regions involving different buffering mechanism. The BNC is primarily from buffers of dissolved Fe, Al and hydrogen sulfate. The BNC can be approximated by: BNC = 3(CFe + CAl) + 0.05Csulfate, where the units are mol/L. The BNC of the sample from the mine is 9.25 × 10-3 mol/L and that of the dumps sample is 1.28 × 10-2 mol/L.

  19. Titration of Isolated Cell Walls of Lemna minor L 1

    Science.gov (United States)

    Morvan, Claudine; Demarty, Maurice; Thellier, Michel

    1979-01-01

    A theoretical model has been built to bypass the equation of titration of the cell wall. This equation, which is an extension of the Henderson-Hasselbach equation, underlines the importance of the exchange constant, the ionic strength as well as the rate of neutralization. The model is restricted to the case when the ionization degree is equal to the neutralization degree. The shape of the titration curve is shown to be strongly dependent on the valency of the base used. Experimental results have shown that isolated cell walls bear at least two kinds of sites. The first sites which are titrated after a short time of equilibration are attributed to polyuronic acids (capacity: 0.3 milliequivalents per gram fresh cell walls). The second sites, are obtained after a long time of equilibration (capacity: 1.2 to 1.3 milliequivalents per gram, fresh cell walls). Titrations have been performed with different bases [KOH, NaOH, and Ca(OH)2] and under different ionic strengths. The results obtained with NaOH and KOH do not exhibit any difference of selectivity. Conversely, the sites have a much bigger affinity for the Ca2+ ions than for the monovalent ones. The apparent pKa of the uronic acids was estimated to lie between 3.0 and 3.4; this is consistent with the values obtained with polyuronic acid solutions. PMID:16660868

  20. potentiometric titration curves of aluminium salt solutions and its ...

    African Journals Online (AJOL)

    a

    In addition, the changes of critical points reflect the influence of experiment ... organic acid radical on the titration curves and its critical points were observed. ..... According to the theory of hard and soft acids and bases (HSAB), Al3+ ion ...

  1. Analysis of the Purity of Cetrimide by Titrations

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Rasmussen, Claus/Dallerup; Nielsen, Hans/Boye

    2006-01-01

    The purity of cetrimide, trimethyl tetradecyl ammonium bromide (TTAB), that is an important preservative of many cosmetic and pharmaceutical products, was determined by three independent methods of titration. Traditionally, cetrimide was analysed by an assay method of the European Pharmacopoeia (Ph...

  2. Micronutrient intakes in a group of UK vegans and the contribution of self-selected dietary supplements.

    Science.gov (United States)

    Lightowler, H J; Davies, G J

    2000-06-01

    Micronutrient intakes and the contribution of self-selected dietary supplements were investigated in 26 vegans, comprising 17 non-supplement users (NSU) and nine supplement users (SU), consuming their habitual diet. Micronutrient intakes were estimated using a four-day weighed record and the contribution of self-selected dietary supplements was assessed according to the manufacturers' declarations on the packaging. Mean daily intakes from food sources were similar in NSU and SU. Dietary supplements significantly increased intakes of riboflavin (p B12 and selenium (Se) were below the appropriate lower reference nutrient intake (LRNI) in 80% and 65% of NSU respectively. After supplements, 33% of SU remained below the LRNI for vitamin B12 and 33% below the LRNI for Se. Some vegans who took supplements were not taking certain micronutrients in amounts sufficient to meet the RNIs but were taking a mix of micronutrients, some of which they needed and others which they did not need. Some vegans who did not take supplements had a potential need for the addition of supplements to their diets. Advice on the appropriate usage of dietary supplements for those on a vegan diet is needed.

  3. European Group for Atomic Spectroscopy. Summaries of contributions, eleventh annual conference, Paris-Orsay, July 10-13, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-07-01

    Summaries are presented of talks given at the eleventh conference of the European group for atomic spectroscopy. Topics covered include: lifetimes; collisions; line shape; hyperfine structure; isotope shifts; saturation spectroscopy; Hanle effect; Rydberg levels; quantum beats; helium and helium-like atoms; metrology; and molecules. (GHT)

  4. A Comprehensive Methodology for Development, Parameter Estimation, and Uncertainty Analysis of Group Contribution Based Property Models -An Application to the Heat of Combustion

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Marcarie, Camille; Abildskov, Jens

    2016-01-01

    A rigorous methodology is developed that addresses numerical and statistical issues when developing group contribution (GC) based property models such as regression methods, optimization algorithms, performance statistics, outlier treatment, parameter identifiability, and uncertainty...... to calculate parameter estimation errors when underlying distribution of residuals is unknown. Many parameters (first,second, third order group contributions) are found unidentifiable from the typically available data, with large estimation error bounds and significant correlation. Due to this poor parameter...... identifiability issues, reporting of the 95% confidence intervals of the predicted property values should be mandatory as opposed to reporting only single value prediction, currently the norm in literature. Moreover, inclusion of higher order groups (additional parameters) does not always lead to improved...

  5. Contributions of a Group-Based Exercise Program for Coping with Fibromyalgia: A Qualitative Study Giving Voice to Female Patients

    OpenAIRE

    Beltrán Carrillo, Vicente J.; Tortosa Martínez, Juan; Jennings, George; Sánchez, Elena S.

    2013-01-01

    Numerous quantitative studies have illustrated the potential usefulness of exercise programs for women with fibromyalgia. However, a deeper understanding of the physical and especially psychosocial benefits of exercise therapy from the subjective perspective of this population is still needed. This study was conducted with 25 women who had fibromyalgia and were participating in a nine-month, group-based exercise program. The aim was to provide an in-depth description and analysis of the perce...

  6. When acid-base titrations are carried out in unusual conditions

    OpenAIRE

    Domenico De Marco; Rocco De Marco

    2012-01-01

    Uncommon aspects in acid-base titrations are presented, which occur in titrations between both mono- and/or poly-functional acid and bases but are rarely introduced in ordinary analytical chemistry courses.

  7. Quantitative proteomic analysis reveals that antioxidation mechanisms contribute to cold tolerance in plantain (Musa paradisiaca L.; ABB Group) seedlings.

    Science.gov (United States)

    Yang, Qiao-Song; Wu, Jun-Hua; Li, Chun-Yu; Wei, Yue-Rong; Sheng, Ou; Hu, Chun-Hua; Kuang, Rui-Bin; Huang, Yong-Hong; Peng, Xin-Xiang; McCardle, James A; Chen, Wei; Yang, Yong; Rose, Jocelyn K C; Zhang, Sheng; Yi, Gan-Jun

    2012-12-01

    Banana and its close relative, plantain are globally important crops and there is considerable interest in optimizing their cultivation. Plantain has superior cold tolerance compared with banana and a thorough understanding of the molecular mechanisms and responses of plantain to cold stress has great potential value for developing cold tolerant banana cultivars. In this study, we used iTRAQ-based comparative proteomic analysis to investigate the temporal responses of plantain to cold stress. Plantain seedlings were exposed for 0, 6, and 24 h of cold stress at 8 °C and subsequently allowed to recover for 24 h at 28 °C. A total of 3477 plantain proteins were identified, of which 809 showed differential expression from the three treatments. The majority of differentially expressed proteins were predicted to be involved in oxidation-reduction, including oxylipin biosynthesis, whereas others were associated with photosynthesis, photorespiration, and several primary metabolic processes, such as carbohydrate metabolic process and fatty acid beta-oxidation. Western blot analysis and enzyme activity assays were performed on seven differentially expressed, cold-response candidate plantain proteins to validate the proteomics data. Similar analyses of the seven candidate proteins were performed in cold-sensitive banana to examine possible functional conservation, and to compare the results to equivalent responses between the two species. Consistent results were achieved by Western blot and enzyme activity assays, demonstrating that the quantitative proteomics data collected in this study are reliable. Our results suggest that an increase of antioxidant capacity through adapted ROS scavenging capability, reduced production of ROS, and decreased lipid peroxidation contribute to molecular mechanisms for the increased cold tolerance in plantain. To the best of our knowledge, this is the first report of a global investigation on molecular responses of plantain to cold stress by

  8. Quantitative Proteomic Analysis Reveals that Antioxidation Mechanisms Contribute to Cold Tolerance in Plantain (Musa paradisiaca L.;ABB Group) Seedlings

    Institute of Scientific and Technical Information of China (English)

    Qiaosong Yang; Junhua Wu; Chunyu Li; Yuerong Wei; Ou Sheng; Chunhua Hu; Ruibin Kuang

    2012-01-01

    Banana and its close relative,plantain are globally important crops and there is of considerable interest in optimizing their cultivation.Plantain has superior cold tolerance compared to banana and a thorough understanding of the molecular mechanisms and responses of plantain to cold stress has great potential value for developing cold tolerant banana cultivars.In this study,we used iTRAQ-based comparative proteomic analysis to investigate the temporal responses of plantain to cold stress.Plantain seedlings were exposed for 0,6 and 24 h of cold stress at 8℃ and subsequently allowed to recover for 24 h at 28℃.A total of 3,477 plantain proteins were identified,of which 809 showed differential expression from the three treatments.The majority of differentially expressed proteins were predicted to be involved in oxidation-reduction,including oxylipin biosynthesis,while others were associated with photosynthesis,photorespiration and several primary metabolic processes,such as carbohydrate metabolic process and fatty acid beta-oxidation.Western blot analysis and enzyme activity assays were performed on 7 differentially expressed,cold-response candidate plantain proteins in order to validate the proteomics data.Similar analyses of the 7 candidate proteins were performed in cold-sensitive banana to examine possible functional conservation and to compare the results to equivalent responses between the two species.Consistent results were achieved by Western blot and enzyme activity assays,demonstrating that the quantitative proteomics data collected in this study are reliable.Our results suggest that an increase of antioxidant capacity through adapted ROS scavenging capability,reduced production of ROS and decreased lipid peroxidation contribute to molecular mechanisms for the higher cold tolerance in plantain.To the best of our knowledge,this is the first report of a global investigation on molecular responses of plantain to cold stress by proteomic analysis.

  9. How can a brief intervention contribute to coping with back pain? A focus group study about participants’ experiences

    DEFF Research Database (Denmark)

    Ree, Eline; Harris, A.; Indahl, A

    2014-01-01

    BACKGROUND: Our aim was to explore how individuals who had participated in a brief back and neck pain intervention perceived connections between the intervention and their subsequent coping. METHODS: Three focus group discussions were conducted with a sample of ten employees aged 20-67 years, who...... had participated in a brief intervention for back and neck pain, perceived the intervention as helpful and had returned or remained at work subsequent to the intervention. Participants were invited to share stories of how the intervention had made a positive difference to their work situation...... and everyday life and helped them cope with their complaints. Systematic text condensation was used for analysis. RESULTS: Analysis revealed several aspects of how the participants considered the intervention to be helpful. They emphasized the importance of having the information delivered in a comprehensible...

  10. Critical Evaluation of Thermochemical Properties of C1-C4 Species: Updated Group-Contributions to Estimate Thermochemical Properties

    Science.gov (United States)

    Burke, S. M.; Simmie, J. M.; Curran, H. J.

    2015-03-01

    A review of literature on enthalpies of formation and molar entropies for alkanes, alkenes, alcohols, hydroperoxides, and their associated radicals has been compiled and critically evaluated. By comparing literature values, the overall uncertainty in thermochemical properties of small hydrocarbons and oxygenated hydrocarbons can be highlighted. In general, there is good agreement between heat of formation values in the literature for stable species; however, there is greater uncertainty in the values for radical species and for molar entropy values. Updated values for a group-additivity method for the estimation of thermochemical properties based on the evaluated literature data are proposed. The new values can be used to estimate thermochemical data for larger, combustion-relevant species for which no calculations or measurements currently exist, with increased confidence.

  11. Seasonal Variations in the Contributions of Different Bacterial Groups to the Uptake of Low-Molecular-Weight Compounds in Northwestern Mediterranean Coastal Waters▿

    Science.gov (United States)

    Alonso-Sáez, Laura; Gasol, Josep M.

    2007-01-01

    We analyzed the contributions of different heterotrophic bacterial groups to the uptake of several low-molecular weight compounds during a seasonal cycle on the northwestern Mediterranean coast (Blanes Bay Microbial Observatory). The bacterial assemblage structure had been shown to change substantially year-round for this site, but whether changes in the activities of the different bacterial groups also occurred on the seasonal scale was unknown. Microautoradiography combined with catalyzed reporter deposition fluorescence in situ hybridization was used to analyze the patterns of glucose, amino acid, and ATP uptake by different bacterial groups. Gammaproteobacteria and Bacteroidetes were not very active in the uptake of glucose at any time of the year (20% of cells were active). Dissolved free amino acids were taken up considerably by Alphaproteobacteria and Gammaproteobacteria but not by Bacteroidetes. Relatively high percentages of cells of the three broad phylogenetic groups actively took up ATP, which could be related to the important phosphorous limitation of bacterial production during most of the year in Blanes Bay. The contribution of SAR11 to the uptake of the monomers was variable year-round, generally with fewer than 30% of the cells being active. By contrast, Roseobacter were highly overrepresented in the uptake of all the substrates throughout all the year, with more than 50% of cells being active in all the samples and for all substrates. Our results suggest that substantial changes in the activity of some phylogenetic groups of bacteria occur throughout the year. PMID:17400772

  12. Revisiting the Dielectric Constant Effect on the Nucleophile and Leaving Group of Prototypical Backside Sn2 Reactions: a Reaction Force and Atomic Contribution Analysis.

    Science.gov (United States)

    Pedraza-González, Laura Milena; Galindo, Johan Fabian; Gonzalez, Ronald; Reyes, Andrés

    2016-10-09

    The solvent effect on the nucleophile and leaving group atoms of the prototypical F(-) + CH3Cl → CH3F + Cl(-) backside bimolecular nucleophilic substitution reaction (SN2) is analyzed employing the reaction force and the atomic contributions methods on the intrinsic reaction coordinate (IRC). Solvent effects were accounted for using the polarizable continuum solvent model. Calculations were performed employing eleven dielectric constants, ε, ranging from 1.0 to 78.5, to cover a wide spectrum of solvents. The reaction force data reveals that the solvent mainly influences the region of the IRC preceding the energy barrier, where the structural rearrangement to reach the transition state occurs. A detailed analysis of the atomic role in the reaction as a function of ε reveals that the nucleophile and the carbon atom are the ones that contribute the most to the energy barrier. In addition, we investigated the effect of the choice of nucleophile and leaving group on the ΔE0 and ΔE(↕) of Y(-) + CH3X → YCH3 + X(-) (X,Y= F, Cl, Br, I) in aqueous solution. Our analysis allowed us to find relationships between the atomic contributions to the activation energy and leaving group ability and nucleophilicity.

  13. Analysis of the Contribution of Chromophores in Side Groups of Amino Acids to the Absorption Spectrum of Hemoglobin

    Science.gov (United States)

    Lavrinenko, I. A.; Vashanov, G. A.; Ruban, M. K.

    2014-01-01

    Based on spectral analysis of solutions of aromatic, heterocyclic, and sulfur-containing amino acids, we propose an additive model and assess the roles of the studied types of amino acid residues in formation of the overall absorption spectrum of hemoglobin. We have established that the identified absorption maxima (transitions) at 243.4, 248.4, 253.2, 258.8, 261.6, 264.8, and 268.4 nm belong to phenylalanine amino acid residues. Probably the latter also form the unassigned transition at 241.0 nm. The transitions at 272.8, 274.6, 280.0, and 284.4 nm are a superposition of the absorption by the side groups of tyrosine and tryptophan; the transition at 278.2 nm is associated with tyrosine, masked by adjacent transitions of tryptophan, and the transition at 291.2 nm belongs to tryptophan. We consider the possibility of estimating the changes in the spectral properties of proteins under the influence of various physical and chemical factors using data from additive spectra.

  14. The contribution of ethnic groups to Malaysian scientific output, 1982-2014, and the effects of the new economic policy.

    Science.gov (United States)

    Lewison, Grant; Kumar, Sameer; Wong, Chan-Yuan; Roe, Philip; Webber, Richard

    2016-01-01

    Malaysia has three main ethnic communities: Chinese, Indians and Malays. At independence in 1957, the Chinese dominated commercial life, and this led to ethnic tensions and finally riots. As a result in 1969 Malaysia introduced a "New Economic Policy" (NEP) to promote Malays in all areas of activity, and in particular to assist them to obtain basic and higher education. We examined the scientific outputs from Malaysia between 1982 and 2014 and classified the names of Malaysian researchers into one of these three groups and two others. There was a major increase in Malay participation in research, which has risen from 20 % of researchers in 1982-1984 to 65 % in 2012-2014, with corresponding declines in the percentages of Chinese and Indian authors, although their absolute numbers have increased because Malaysian scientific output has increased so rapidly in the last 10 years. The huge increase in Malay researchers contrasts with their presence in the Malaysian population which has remained stable at about 50 % since 1969.

  15. Applications of isothermal titration calorimetry in protein science.

    Science.gov (United States)

    Liang, Yi

    2008-07-01

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

  16. Monitoring RNA-ligand interactions using isothermal titration calorimetry.

    Science.gov (United States)

    Gilbert, Sunny D; Batey, Robert T

    2009-01-01

    Isothermal titration calorimetry (ITC) is a biophysical technique that measures the heat evolved or absorbed during a reaction to report the enthalpy, entropy, stoichiometry of binding, and equilibrium association constant. A significant advantage of ITC over other methods is that it can be readily applied to almost any RNA-ligand complex without having to label either molecule and can be performed under a broad range of pH, temperature, and ionic concentrations. During our application of ITC to investigate the thermodynamic details of the interaction of a variety of compounds with the purine riboswitch, we have explored and optimized experimental parameters that yield the most useful and reproducible results for RNAs. In this chapter, we detail this method using the titration of an adenine-binding RNA with 2,6-diaminopurine (DAP) as a practical example. Our insights should be generally applicable to observing the interactions of a broad range of molecules with structured RNAs.

  17. Applications of isothermal titration calorimetry in protein science

    Institute of Scientific and Technical Information of China (English)

    Yi Liang

    2008-01-01

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

  18. Contribution of the RgfD Quorum Sensing Peptide to rgf Regulation and Host Cell Association in Group B Streptococcus

    Science.gov (United States)

    Parker, Robert E.; Knupp, David; Al Safadi, Rim; Rosenau, Agnѐs; Manning, Shannon D.

    2017-01-01

    Streptococcus agalactiae (group B Streptococcus; GBS) is a common inhabitant of the genitourinary and/or gastrointestinal tract in up to 40% of healthy adults; however, this opportunistic pathogen is able to breach restrictive host barriers to cause disease and persist in harsh and changing conditions. This study sought to identify a role for quorum sensing, a form of cell to cell communication, in the regulation of the fibrinogen-binding (rgfBDAC) two-component system and the ability to associate with decidualized endometrial cells in vitro. To do this, we created a deletion in rgfD, which encodes the putative autoinducing peptide, in a GBS strain belonging to multilocus sequence type (ST)-17 and made comparisons to the wild type. Sequence variation in the rgf operon was detected in 40 clinical strains and a non-synonymous single nucleotide polymorphism was detected in rgfD in all of the ST-17 genomes that resulted in a truncation. Using qPCR, expression of rgf operon genes was significantly decreased in the ST-17 ΔrgfD mutant during exponential growth with the biggest difference (3.3-fold) occurring at higher cell densities. Association with decidualized endometrial cells was decreased 1.3-fold in the mutant relative to the wild type and rgfC expression was reduced 22-fold in ΔrgfD following exposure to the endometrial cells. Collectively, these data suggest that this putative quorum sensing molecule is important for attachment to human tissues and demonstrate a role for RgfD in GBS pathogenesis through regulation of rgfC. PMID:28067833

  19. BibA: a novel immunogenic bacterial adhesin contributing to group B Streptococcus survival in human blood.

    Science.gov (United States)

    Santi, Isabella; Scarselli, Maria; Mariani, Massimo; Pezzicoli, Alfredo; Masignani, Vega; Taddei, Annarita; Grandi, Guido; Telford, John L; Soriani, Marco

    2007-02-01

    By the analysis of the recently sequenced genomes of Group B Streptococcus (GBS) we have identified a novel immunogenic adhesin with anti-phagocytic activity, named BibA. The bibA gene is present in 100% of the 24 GBS strains analysed. BibA-specific IgG were found in human sera from normal healthy donors. The putative protein product is a polypeptide of 630 amino acids containing a helix-rich N-terminal domain, a proline-rich region and a canonical LPXTG cell wall-anchoring domain. BibA is expressed on the surface of several GBS strains, but is also recovered in GBS culture supernatants. BibA specifically binds to human C4-binding protein, a regulator of the classic complement pathway. Deletion of the bibA gene severely reduced the capacity of GBS to survive in human blood and to resist opsonophagocytic killing by human neutrophils. In addition, BibA expression increased the virulence of GBS in a mouse infection model. The role of BibA in GBS adhesion was demonstrated by the impaired ability of a bibA knockout mutant strain to adhere to both human cervical and lung epithelial cells. Furthermore, we calculated that recombinant BibA bound to human epithelial cells of distinct origin with an affinity constant of approximately 10(-8) M for cervical epithelial cells. Hence BibA is a novel multifunctional protein involved in both resistance to phagocytic killing and adhesion to host cells. The identification of this potential new virulence factor represents an important step in the development of strategies to combat GBS-associated infections.

  20. Determination of total acidity index in bioethanol by automated potentiometric titration; Determinacao do indice de acidez total em bioetanol por titulacao potenciometrica automatizada

    Energy Technology Data Exchange (ETDEWEB)

    Sobral, Sidney Pereira; Ribeiro, Carla de Matos; Fraga, Isabel Cristina Serta; Goncalves, Mary Ane [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (DIMCI/INMETRO), Duque de Caxias, RJ (Brazil). Diretoria de Metrologia Cientifica e Industrial], E-mail: spsobral@inmetro.gov.br

    2009-07-01

    This paper determines the total acidity index of bioethanol by volumetric titration with potentiometric detection. Also, viewing the optimization of the method, studies are exhibited related to the repeatable, besides the comparison with the colorimetric method with the objective to contribute to the certification of bioethanol reference materials.

  1. Monitoring assembly of ribonucleoprotein complexes by isothermal titration calorimetry

    OpenAIRE

    Recht, Michael I; Ryder, Sean P.; Williamson, James R.

    2008-01-01

    Isothermal titration calorimetry (ITC) is a useful technique to study RNA-protein interactions, as it provides the only method by which the thermodynamic parameters of free energy, enthalpy, and entropy can be directly determined. This chapter presents a general procedure for studying RNA-protein interactions using ITC, and gives specific examples for monitoring the binding of Caenorhabditis elegans GLD-1 STAR domain to TGE RNA and the binding of Aquifex aeolicus S6:S18 ribosomal protein hete...

  2. Solubility of strontium-substituted apatite by solid titration

    OpenAIRE

    Pan, HB; Darvell, BW; Luk, KDK; Lu, WW; Li, ZY; Lam, WM; Wong, JC

    2009-01-01

    Solid titration was used to explore the solubility isotherms of partially (Srx-HAp, x = 1, 5, 10, 40, 60 mol.%) and fully substituted strontium hydroxyapatite (Sr-HAp). Solubility increased with increasing strontium content. No phase other than strontium-substituted HAp, corresponding to the original titrant, was detected in the solid present at equilibrium; in particular, dicalcium hydrogen phosphate was not detected at low pH. The increase in solubility with strontium content is interpreted...

  3. A titration microcalorimeter and the vesicle of mixed surfactants

    Institute of Scientific and Technical Information of China (English)

    白光月[1; 王玉洁[2; 王金本[3; 杨冠英[4; 韩布兴[5; 闫海科[6

    2000-01-01

    A titration microcalorimeter with the sample cells of 1 mL and 3 mL volume was constructed by combining LKB-2107 ampule microcalorimeter with an improved Thermometric titration microcalorimeter. Its sensitivity and precision were tested with the baseline noise and stability, the measurement of energy equivalent, and the linear relation of electric energy and integral area as the function of voltage (V)-time (f). Its accuracy was demonstrated by measuring the dilution enthalpy of a concentrated sucrose solution and the micelle-forming enthalpy of sodium dodecyl sulfate (SDS) in aqueous solution respectively. At the same time, the enthalpy of interaction between SDS and didodecyldimethylammonium bromide (DDAB) was measured by using the titration microcalorimeter, and the phase behavior of SDS-DDAB aqueous mixture was discussed. The microcalorimetric results show that the enthalpy of interaction between SDS and DDAB micelles is -29.53 kJ/mol, the enthalpy of formation of 1:1 SDS-DDAB salt is -125.8 kJ/mol,

  4. A titration microcalorimeter and the vesicle of mixed surfactants

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A titration microcalorimeter with the sample cells of 1 mL and 3 mL volume was constructed by combining LKB-2107 ampule microcalorimeter with an improved Thermometric titration microcalorimeter. Its sensitivity and precision were tested with the baseline noise and stability, the measurement of energy equivalent, and the linear relation of electric energy and integral area as the function of voltage (V )-time (t ). Its accuracy was demonstrated by measuring the dilution enthalpy of a concentrated sucrose solution and the micelle-forming enthalpy of sodium dodecyl sulfate (SDS) in aqueous solution respectively. At the same time, the enthalpy of interaction between SDS and didodecyldimethylammonium bromide (DDAB) was measured by using the titration microcalorimeter, and the phase behavior of SDS-DDAB aqueous mixture was discussed. The microcalorimetric results show that the enthalpy of interaction between SDS and DDAB micelles is ?29.53 kJ/mol, the enthalpy of formation of 1:1 SDS-DDAB salt is ?125.8 kJ/mol, the vesicle-forming enthalpy of SDS-DDAB is 41.23 kJ/mol, and the enthalpy of phase transition from vesicles to SDS rich micelle is 32.10 kJ/mol.

  5. Impact of Residual Inducer on Titratable Expression Systems.

    Directory of Open Access Journals (Sweden)

    Taliman Afroz

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

  6. Summary of contributions to GAW Group 15: family-based samples are useful in identifying common polymorphisms associated with complex traits.

    Science.gov (United States)

    Knight, Stacey; Uh, Hae-Won; Martinez, Maria

    2009-01-01

    Traditionally, family-based samples have been used for genetic analyses of single-gene traits caused by rare but highly penetrant risk variants. The utility of family-based genetic data for analyzing common complex traits is unclear and contains numerous challenges. To assess the utility as well as to address these challenges, members of Genetic Analysis Workshop 16 Group 15 analyzed Framingham Heart Study data using family-based designs ranging from parent--offspring trios to large pedigrees. We investigated different methods including traditional linkage tests, family-based association tests, and population-based tests that correct for relatedness between subjects, and tests to detect parent-of-origin effects. The analyses presented an assortment of positive findings. One contribution found increased power to detect epistatic effects through linkage using ascertainment of sibships based on extreme quantitative values or presence of disease associated with the quantitative value. Another contribution found four single-nucleotide polymorphisms (SNPs) showing a maternal effect, two SNPs with an imprinting effect, and one SNP having both effects on a binary high blood pressure trait. Finally, three contributions illustrated the advantage of using population-based methods to detect association to complex binary or quantitative traits. Our findings highlight the contribution of family-based samples to the genetic dissection of complex traits. (c) 2009 Wiley-Liss, Inc.

  7. A(1c) control in a primary care setting: self-titrating an insulin analog pre-mix (INITIATEplus trial).

    Science.gov (United States)

    Oyer, David S; Shepherd, Mark D; Coulter, Franklin C; Bhargava, Anuj; Brett, Jason; Chu, Pei-Ling; Trippe, Bruce S

    2009-11-01

    To study glycemic control and hypoglycemia development upon initiation of insulin through a self-titration schedule in a 24-week trial, conducted with 4875 insulin-naïve patients with poorly controlled type 2 diabetes, predominantly in a primary care setting. Subjects initiated twice-daily biphasic insulin aspart 70/30 with 6 units prebreakfast and 6 units presupper, self-titrating according to self-measured blood glucose values. Subjects were randomized (1:1:1) to telephone counseling provided by a registered dietician: no counseling (NC), 1 counseling session (1C), or 3 sessions (3C). Mean baseline HbA(1c) (9.9% across groups) decreased approximately 2.5% to 7.49% + or - 1.48, 7.48% + or - 1.50, and 7.44% + or - 1.46 in the NC, 1C, and 3C groups, respectively. Within these groups, a hemoglobin A(1c) (HbA(1c)) value self-titration of biphasic insulin aspart 70/30 was effective in achieving recommended HbA(1c) goals even with minimal dietary counseling.

  8. Randomized clinical trial between hourly titrated and 2 hourly static oral misoprostol solution for induction of labor.

    Science.gov (United States)

    Rouzi, Abdulrahim A; Alsahly, Nora; Alamoudi, Rana; Almansouri, Nisma; Alsinani, Nawal; Alkafy, Souzan; Rozzah, Rayyan; Abduljabbar, Hassan

    2017-04-01

    Misoprostol is an effective agent for the induction of labor. Existing guidelines recommend oral misoprostol solution 25 μg every 2 hours. However, more research is required to optimize the use of oral misoprostol solution for the induction of labor. The purpose of this study was to compare efficacy and safety of hourly titrated-dose oral misoprostol solution with static-dose oral misoprostol solution every 2 hours for labor induction. In this randomized controlled study, oral misoprostol solution was administered as (1) 20 μg hourly (≤4 doses) that was increased in the absence of regular uterine contractions to 40 μg hourly (≤4 doses) and then to 60 μg hourly (≤16 doses) or (2) 25 μg every 2 hours until active labor began (≤12 doses). A sample size of 146 women was planned with the use of a projected 95% rate for the primary endpoint (vaginal delivery within 24 hours) for hourly titrated-dose misoprostol and 80% rate for static-dose misoprostol every 2 hours. Safety outcomes included maternal morbidity and adverse neonatal outcomes. From December 2013 to July 2015, 146 women were assigned randomly to treatment. Demographic and clinical factors were similar between groups, except for age. Vaginal delivery was achieved within 24 hours in 47 women (64.4%) who received hourly titrated-doses of misoprostol solution and 48 women (65.8%) who received 2-hourly static-dose misoprostol solution (P=1.00). Rates of vaginal delivery within 24 hours did not differ significantly between treatment groups for women who were nulliparous (P=1.00) or who had postterm pregnancies (P=.66), a Bishop score of ≤3 (P=.84), or oxytocin augmentation (P=.83). Cesarean deliveries were performed within 24 hours in 9 women who received hourly titrated-dose misoprostol solution and 2 women who received 2-hourly static-dose misoprostol solution (P=.056). Pyrexia and meconium-stained liquor occurred more frequently with the hourly titrated-dose regimen. The static-dose oral

  9. Copper and cobalt complexes of octadentate azamacrocycles: spectrophotometric titration, stopped-flow kinetics and crystallographic study.

    Science.gov (United States)

    Ozay, Hava; Baran, Yakup; Ishii, Youichi

    2011-12-01

    Details of complex formation kinetics are reported for tetrakis(2-hydroxyethyl) substituted cyclen (L(1)) and cyclam (L(2)) with Cu(II) and Co(II). Stopped-flow kinetics and spectroscopic titration methods were employed for the activation parameters and stability constants, respectively. X-ray studies revealed that the pendant 2-hydroxyethyl groups are not equivalent: two are folded over the macrocycle and maintained by intramolecular hydrogen bonds while the others are extended and pointed away from the macrocyclic cavity. Complex formation kinetics and spectroscopic titration were performed in aqueous acidic buffer solutions. Thermodynamic and kinetic parameters revealed that the ring size of the macrocycles plays an extremely important role for each metal ion studied. Stopped-flow kinetic measurements explained the mechanism of the complex formation process of both Cu(II) and Co(II) which proceed in outer-sphere interactions with ligands. There are two steps in the complex formation of the system studied. The initial step is a second order reaction between the metal ion and macrocycle with a second order rate constant.

  10. Monitoring assembly of ribonucleoprotein complexes by isothermal titration calorimetry

    Science.gov (United States)

    Recht, Michael I.; Ryder, Sean P.; Williamson, James R.

    2010-01-01

    Isothermal titration calorimetry (ITC) is a useful technique to study RNA-protein interactions, as it provides the only method by which the thermodynamic parameters of free energy, enthalpy, and entropy can be directly determined. This chapter presents a general procedure for studying RNA-protein interactions using ITC, and gives specific examples for monitoring the binding of Caenorhabditis elegans GLD-1 STAR domain to TGE RNA and the binding of Aquifex aeolicus S6:S18 ribosomal protein heterodimer to an S15-rRNA complex. PMID:18982287

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

    Science.gov (United States)

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

    2016-01-01

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

  12. Isothermal Titration Calorimetry of Membrane Proteins – Progress and Challenges

    Science.gov (United States)

    Rajarathnam, Krishna; Rösgen, Jörg

    2013-01-01

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

  13. Characterization of Native and Modified Starches by Potentiometric Titration

    Directory of Open Access Journals (Sweden)

    Diana Soto

    2014-01-01

    Full Text Available The use of potentiometric titration for the analysis and characterization of native and modified starches is highlighted. The polyelectrolytic behavior of oxidized starches (thermal and thermal-chemical oxidation, a graft copolymer of itaconic acid (IA onto starch, and starch esters (mono- and diester itaconate was compared with the behavior of native starch, the homopolymer, and the acid employed as a graft monomer and substituent. Starch esters showed higher percentages of acidity, followed by graft copolymer of itaconic acid and finally oxidized starches. Analytical techniques and synthesis of modified starches were also described.

  14. Contribuições do pensamento construcionista para o estudo da prática grupal Constructionist's contributions for the study of group work

    Directory of Open Access Journals (Sweden)

    Emerson F. Rasera

    2001-01-01

    Full Text Available O construcionismo, como forma de elaboração da crise paradigmática que têm vivido as ciências humanas, redimensiona várias concepções sobre a produção do conhecimento e os processos psicoterápicos. Neste artigo, buscaremos apontar como a ênfase nos processos relacionais e a centralidade da linguagem promovidas pelo construcionismo transformam o estudo da prática grupal. Através de um exemplo empírico, apontaremos algumas implicações metodológicas da aplicação dos pressupostos construcionistas ao estudo da prática grupal, tais como a explicitação do caráter construído do grupo e seu processo de negociação, a perspectiva discursiva de construção da pessoa e a conseqüente redefinição da homogeneidade grupal, e as delimitações sociais destes processos grupais. Finalizamos o artigo indicando outros desdobramentos teórico-metodológicos necessários ao desenvolvimento destas contribuições aos estudos dos grupos.Social constructionism, as a human sciences paradigmatic crisis elaboration, rebuilds some conceptions of knowledge production and psychotherapeutic processes. In this article, we point out how the emphasis on the relational processes and the centrality of language promoted by constructionism change the study of group work. Using an empirical example, we consider some methodological implications of constructionist assumptions for the study of group work, as i the constructed character of the group and its negotiating process, ii the discursive approach of person construction and the consequent group homogeneity redefinition and iii the social constraints of group processes. We conclude this article pointing out other theoretical and methodological developments necessary to unfold these contributions to group study.

  15. Determination of acid dissociation constants of some hydroxy schiff bases by pH-metric titration. application of the Hammett equation

    OpenAIRE

    Hadjeb R.; Bara A.; Barkat D.

    2013-01-01

    Ten compounds hydroxybases Schiff were synthesized from salicylaldehyde and the substituted aniline in the ortho, meta and para methyl groups, chloro and nitro. To study the effect of substituents on their acidities, the acid dissociation constants( Ka) of salicylideneaniline and some of their derivatives were determined by pH-metric titration. All Schiff bases were titrated with NaOH in mixtures of 60% dioxane-water and 60% ethanol-water at a constant ionic strength and a temperature of 25 °...

  16. Increasing the Detection Limit of the Parkinson Disorder through a Specific Surface Chemistry Applied onto Inner Surface of the Titration Well

    Directory of Open Access Journals (Sweden)

    Fabienne Poncin-Epaillard

    2012-04-01

    Full Text Available The main objective of this paper was to illustrate the enhancement of the sensitivity of ELISA titration for neurodegenerative proteins by reducing nonspecific adsorptions that could lead to false positives. This goal was obtained thanks to the association of plasma and wet chemistries applied to the inner surface of the titration well. The polypropylene surface was plasma-activated and then, dip-coated with different amphiphilic molecules. These molecules have more or less long hydrocarbon chains and may be charged. The modified surfaces were characterized in terms of hydrophilic—phobic character, surface chemical groups and topography. Finally, the coated wells were tested during the ELISA titration of the specific antibody capture of the α-synuclein protein. The highest sensitivity is obtained with polar (Θ = 35°, negatively charged and smooth inner surface.

  17. Isothermal titration calorimetry: general formalism using binding polynomials.

    Science.gov (United States)

    Freire, Ernesto; Schön, Arne; Velazquez-Campoy, Adrian

    2009-01-01

    The theory of the binding polynomial constitutes a very powerful formalism by which many experimental biological systems involving ligand binding can be analyzed under a unified framework. The analysis of isothermal titration calorimetry (ITC) data for systems possessing more than one binding site has been cumbersome because it required the user to develop a binding model to fit the data. Furthermore, in many instances, different binding models give rise to identical binding isotherms, making it impossible to discriminate binding mechanisms using binding data alone. One of the main advantages of the binding polynomials is that experimental data can be analyzed by employing a general model-free methodology that provides essential information about the system behavior (e.g., whether there exists binding cooperativity, whether the cooperativity is positive or negative, and the magnitude of the cooperative energy). Data analysis utilizing binding polynomials yields a set of binding association constants and enthalpy values that conserve their validity after the correct model has been determined. In fact, once the correct model is validated, the binding polynomial parameters can be immediately translated into the model specific constants. In this chapter, we describe the general binding polynomial formalism and provide specific theoretical and experimental examples of its application to isothermal titration calorimetry.

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

    Science.gov (United States)

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

    2016-01-01

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

  19. Semi-automated potentiometric titration method for uranium characterization

    Energy Technology Data Exchange (ETDEWEB)

    Cristiano, B.F.G., E-mail: barbara@ird.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Delgado, J.U.; Silva, J.W.S. da; Barros, P.D. de; Araujo, R.M.S. de [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Lopes, R.T. [Programa de Engenharia Nuclear (PEN/COPPE), Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, PO Box 68509, Rio de Janeiro, 21945-970 RJ (Brazil)

    2012-07-15

    The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. - Highlights: Black-Right-Pointing-Pointer We developed a semi-automatic version of potentiometric titration method. Black-Right-Pointing-Pointer The method is used for certification and characterization of uranium compounds. Black-Right-Pointing-Pointer The traceability of the method was assured by a K{sub 2}Cr{sub 2}O{sub 7} primary standard. Black-Right-Pointing-Pointer The results of U{sub 3}O{sub 8} reference material analyzed was consistent with certified value. Black-Right-Pointing-Pointer The uncertainty obtained, near 0.01%, is useful for characterization purposes.

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

    Science.gov (United States)

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

    2015-01-01

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

  1. Estimation of Octanol-Water Partition Coefficient of Chloride Hydrocarbon by Group Contribution Method%基团贡献法估算氯代化合物正辛醇-水分配系数

    Institute of Scientific and Technical Information of China (English)

    梁英华; 陈红萍

    2007-01-01

    A novel method named two-level group contribution (GC-K) method for the estimation of octanol-water partition coefficient (Kow) of chloride hydrocarbon is presented. The equation includes only normal boiling points and molecular weight of compounds. Group contribution parameters of 12 first-level groups and 7 second-level groups for Kow are obtained by correlating experimental data of three types including 57 compounds. By comparing the estimation results of the first-level with that of the two-level groups, it was observed that the latter is better with the addition of the modification of proximity effects. When compared with Marrero's three-level group contribution approach and atom-fragment contribution method (AFC), the accuracy of the average relative error of GC-K by first-level groups is 7.20% and is preferred to other methods.

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

    Science.gov (United States)

    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.

  3. Change of caged dynamics at Tg in hydrated proteins: Trend of mean squared displacements after correcting for the methyl-group rotation contribution

    Science.gov (United States)

    Ngai, K. L.; Capaccioli, S.; Paciaroni, A.

    2013-06-01

    The question whether the dynamics of hydrated proteins changes with temperature on crossing the glass transition temperature like that found in conventional glassformers is an interesting one. Recently, we have shown that a change of temperature dependence of the mean square displacement (MSD) at Tg is present in proteins solvated with bioprotectants, such as sugars or glycerol with or without the addition of water, coexisting with the dynamic transition at a higher temperature Td. The dynamical change at Tg is similar to that in conventional glassformers at sufficiently short times and low enough temperatures, where molecules are mutually caged by the intermolecular potential. This is a general and fundamental property of glassformers which is always observed at or near Tg independent of the energy resolution of the spectrometer, and is also the basis of the dynamical change of solvated proteins at Tg. When proteins are solvated with bioprotectants they show higher Tg and Td than the proteins hydrated by water alone, due to the stabilizing action of excipients, thus the observation of the change of T-dependence of the MSD at Tg is unobstructed by the methyl-group rotation contribution at lower temperatures [S. Capaccioli, K. L. Ngai, S. Ancherbak, and A. Paciaroni, J. Phys. Chem. B 116, 1745 (2012)], 10.1021/jp2057892. On the other hand, in the case of proteins hydrated by water alone unambiguous evidence of the break at Tg is hard to find, because of their lower Tg and Td. Notwithstanding, in this paper, we provide evidence for the change at Tg of the T-dependence of proteins hydrated by pure water. This evidence turns out from (i) neutron scattering experimental investigations where the sample has been manipulated by either full or partial deuteration to suppress the methyl-group rotation contribution, and (ii) neutron scattering experimental investigations where the energy resolution is such that only motions with characteristic times shorter than 15 ps can be

  4. Potential estimation of titratable acidity in cow milk using mid-infrared spectrometry

    OpenAIRE

    Colinet, Frédéric; Soyeurt, Hélène; Anceau, Christine; Vanlierde, Amélie; Keyen, Nicolas; Pierre DARDENNE; Gengler, Nicolas; Sindic, Marianne

    2010-01-01

    Milk coagulation has a direct effect on cheese yield. Several factors influence the milk coagulation kinetics. In addition to calcium and milk protein concentrations, titratable acidity influences all the phases of milk coagulation. The objective of this research was to study the feasibility of prediction of titratable acidity directly in bovine milk using mid-infrared spectrometry. In order to maximize the variability in the measurements of titratable acidity, milk samples were collected on ...

  5. Analysis of the contribution of forest pathways to the radiation exposure of different population groups in the Bryansk region of Russia.

    Science.gov (United States)

    Fesenko, S V; Voigt, G; Spiridonov, S I; Sanzharova, N I; Gontarenko, I A; Belli, M; Sansone, U

    2000-12-01

    The experience gained in the aftermath of serious radiation accidents shows that forests are an important source of external and internal exposure of the affected population. This paper presents the results of an assessment of the major radiological consequences for forests of Russia, most heavily contaminated after the Chernobyl nuclear power plant (ChNPP) accident. Illustrated in the Novozybkovsky district of the Russian Federation, the significance of different forest exposure pathways is estimated and the doses resulting from forest pathways are compared with the doses from agricultural products. It has been found that the contribution of mushrooms and berries to the internal doses of the population, relative to the doses from agricultural products, varied from 10-15% in 1987 to 40-45% in 1996. The results indicate large differences in internal exposure of members of the "critical groups" and "normal population", increasing with time after deposition. Data are presented that give information on the contribution of forests to the collective doses of inhabitants of the area under consideration. It has been shown that for 10 years after the accident (1987-1996), the contribution of forest products to the collective dose of the rural population living in contaminated forests of the Novozybkovsky district, amounts to about 20% (213 person Sv) of the total collective dose of internal and external exposures. However, a potential impact of these products including the dose from exported products is much higher and might reach 659 person Sv. It has been found that in the long-term after the ChNPP accident, serious attention should be given to forest countermeasures, and restoration strategies should be selected on the basis of a combined analysis of the effectiveness of forest and agricultural countermeasures.

  6. A Comprehensive Methodology for Development, ParameterEstimation, and Uncertainty Analysis of Group Contribution Based Property Models -An Application to the Heat of Combustion

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Marcarie, Camille; Abildskov, Jens;

    2016-01-01

    of the prediction. The methodology is evaluated through development of a GC method for the prediction of the heat of combustion (ΔHco) for pure components. The results showed that robust regression lead to best performance statistics for parameter estimation. The bootstrap method is found to be a valid alternative......A rigorous methodology is developed that addresses numerical and statistical issues when developing group contribution (GC) based property models such as regression methods, optimization algorithms, performance statistics, outlier treatment, parameter identifiability, and uncertainty...... prediction accuracy for the GC-models; in some cases, it may even increase the prediction error (hence worse prediction accuracy). However, additional parameters do not affect calculated 95% confidence interval. Last but not least, the newly developed GC model of the heat of combustion (ΔHco) shows...

  7. Subvisible retinal laser therapy: titration algorithm and tissue response.

    Science.gov (United States)

    Lavinsky, Daniel; Sramek, Christopher; Wang, Jenny; Huie, Philip; Dalal, Roopa; Mandel, Yossi; Palanker, Daniel

    2014-01-01

    Laser therapy for diabetic macular edema and other retinal diseases has been used within a wide range of laser settings: from intense burns to nondamaging exposures. However, there has been no algorithm for laser dosimetry that could determine laser parameters yielding a predictable extent of tissue damage. This multimodal imaging and structural correlation study aimed to verify and calibrate a computational model-based titration algorithm for predictable laser dosimetry ranging from nondamaging to intense coagulative tissue effects. Endpoint Management, an algorithm based on a computational model of retinal photothermal damage, was used to set laser parameters for various levels of tissue effect. The algorithm adjusts both power and pulse duration to vary the expected level of thermal damage at different percentages of a reference titration energy dose. Experimental verification was conducted in Dutch Belted rabbits using a PASCAL Streamline 577 laser system. Titration was performed by adjusting laser power to produce a barely visible lesion at 20 ms pulse duration, which is defined as the nominal (100%) energy level. Tissue effects were then determined for energy levels of 170, 120, 100, 75, 50, and 30% of the nominal energy at 1 hour and 3, 7, 30, and 60 days after treatment. In vivo imaging included fundus autofluorescence, fluorescein angiography, and spectral-domain optical coherence tomography. Morphologic changes in tissue were analyzed using light microscopy, as well as scanning and transmission electron microscopy. One hundred and seventy percent and 120% levels corresponded to moderate and light burns, respectively, with damage to retinal pigment epithelium, photoreceptors, and at highest settings, to the inner retina. 50% to 75% lesions were typically subvisible ophthalmoscopically but detectable with fluorescein angiography and optical coherence tomography. Histology in these lesions demonstrated some selective damage to retinal pigment epithelium and

  8. The differences in binding 12-carbon aliphatic ligands by bovine β-lactoglobulin isoform A and B studied by isothermal titration calorimetry and X-ray crystallography.

    Science.gov (United States)

    Loch, Joanna I; Bonarek, Piotr; Polit, Agnieszka; Swiątek, Śylwia; Dziedzicka-Wasylewska, Marta; Lewiński, Krzysztof

    2013-08-01

    Isoforms A (LGB-A) and B (LGB-B) of bovine lactoglobulin, the milk protein, differ in positions 64 (D↔G) and 118 (V↔A). Interactions of LGB-A and LGB-B with sodium dodecyl sulfate (SDS), dodecyltrimethylammonium chloride (DTAC) and lauric acid (LA), 12-carbon ligands possessing differently charged polar groups, were investigated using isothermal titration calorimetry and X-ray crystallography, to study the proton linkage phenomenon and to distinguish between effects related to different isoforms and different ligand properties. The determined values of ΔS and ΔH revealed that for all ligands, binding is entropically driven. The contribution from enthalpy change is lower and shows strong dependence on type of buffer that indicates proton release from the protein varying with protein isoform and ligand type and involvement of LA and Asp64 (in isoform A) in this process. The ligand affinities for both isoforms were arranged in the same order, DTAC enthalpy, resulting in almost identical ΔG for complexes of both isoforms. The determined crystal structures showed that substitution in positions 64 and 118 did not influence the overall structure of LGB complexes. The chemical character of the ligand polar group did not affect the position of its aliphatic chain in protein β-barrel, indicating a major role of hydrophobic interactions in ligand binding that prevailed even with the repulsion between positively charged DTAC and lysine residues located at binding site entrance.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, Jeffrey A., E-mail: Jeffrey.Mertens@ars.usda.gov [Bioenergy Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, IL 61604 (United States); Hector, Ronald E.; Bowman, Michael J. [Bioenergy Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, IL 61604 (United States)

    2012-01-10

    Highlights: Black-Right-Pointing-Pointer Thermodynamics of (GalpA){sub n} oligomers binding to an exo-polygalacturonase. Black-Right-Pointing-Pointer Energetics of binding (GalpA){sub n} were determined by ITC. Black-Right-Pointing-Pointer Thermodynamic parameters attributable to individual subsites were determined. - Abstract: Thermodynamic parameters for binding of a series of galacturonic acid oligomers to an exo-polygalacturonase, RPG16 from Rhizopus oryzae, were determined by isothermal titration calorimetry. Binding of oligomers varying in chain length from two to five galacturonic acid residues is an exothermic process that is enthalpically driven and results in extremely tight binding of the substrate to RPG16. Binding energies in combination with prior biochemical data suggests that RPG16 has the potential for five subsites, -1 to +4, with the greatest contribution to binding energies arising from subsite -1/+1. While the enthalpic contribution to binding decreases substantially for subsites +2 to +4, beneficial entropic effects occur in subsites +3 and +4 leading to increased total free energy as the length of oligomer increases. This information will be useful for additional studies in determining the binding contributions of specific amino acids with mutant enzymes.

  10. Secondary Use and Analysis of Big Data Collected for Patient Care. Contribution from the IMIA Working Group on Data Mining and Big Data Analytics.

    Science.gov (United States)

    Martin-Sanchez, F J; Aguiar-Pulido, V; Lopez-Campos, G H; Peek, N; Sacchi, L

    2017-05-08

    To identify common methodological challenges and review relevant initiatives related to the re-use of patient data collected in routine clinical care, as well as to analyze the economic benefits derived from the secondary use of this data. Through the use of several examples, this article aims to provide a glimpse into the different areas of application, namely clinical research, genomic research, study of environmental factors, and population and health services research. This paper describes some of the informatics methods and Big Data resources developed in this context, such as electronic phenotyping, clinical research networks, biorepositories, screening data banks, and wide association studies. Lastly, some of the potential limitations of these approaches are discussed, focusing on confounding factors and data quality. A series of literature searches in main bibliographic databases have been conducted in order to assess the extent to which existing patient data has been repurposed for research. This contribution from the IMIA working group on "Data mining and Big Data analytics" focuses on the literature published during the last two years, covering the timeframe since the working group's last survey. Although most of the examples of secondary use of patient data lie in the arena of clinical and health services research, we have started to witness other important applications, particularly in the area of genomic research and the study of health effects of environmental factors. Further research is needed to characterize the economic impact of secondary use across the broad spectrum of translational research.

  11. 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

    Directory of Open Access Journals (Sweden)

    Yu Nakamura

    2015-09-01

    Full Text Available 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.

  12. Isothermal Titration Calorimetry for Measuring Macromolecule-Ligand Affinity

    Science.gov (United States)

    Duff,, Michael R.; Grubbs, Jordan; Howell, Elizabeth E.

    2011-01-01

    Isothermal titration calorimetry (ITC) is a useful tool for understanding the complete thermodynamic picture of a binding reaction. In biological sciences, macromolecular interactions are essential in understanding the machinery of the cell. Experimental conditions, such as buffer and temperature, can be tailored to the particular binding system being studied. However, careful planning is needed since certain ligand and macromolecule concentration ranges are necessary to obtain useful data. Concentrations of the macromolecule and ligand need to be accurately determined for reliable results. Care also needs to be taken when preparing the samples as impurities can significantly affect the experiment. When ITC experiments, along with controls, are performed properly, useful binding information, such as the stoichiometry, affinity and enthalpy, are obtained. By running additional experiments under different buffer or temperature conditions, more detailed information can be obtained about the system. A protocol for the basic setup of an ITC experiment is given. PMID:21931288

  13. Isothermal titration calorimetry of ion-coupled membrane transporters.

    Science.gov (United States)

    Boudker, Olga; Oh, SeCheol

    2015-04-01

    Binding of ligands, ranging from proteins to ions, to membrane proteins is associated with absorption or release of heat that can be detected by isothermal titration calorimetry (ITC). Such measurements not only provide binding affinities but also afford direct access to thermodynamic parameters of binding--enthalpy, entropy and heat capacity. These parameters can be interpreted in a structural context, allow discrimination between different binding mechanisms and guide drug design. In this review, we introduce advantages and limitations of ITC as a methodology to study molecular interactions of membrane proteins. We further describe case studies where ITC was used to analyze thermodynamic linkage between ions and substrates in ion-coupled transporters. Similar type of linkage analysis will likely be applicable to a wide range of transporters, channels, and receptors. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Isothermal titration calorimetry of membrane proteins - progress and challenges.

    Science.gov (United States)

    Rajarathnam, Krishna; Rösgen, Jörg

    2014-01-01

    Integral membrane proteins, including G protein-coupled receptors (GPCR) and ion channels, mediate diverse biological functions that are crucial to all aspects of life. The knowledge of the molecular mechanisms, and in particular, the thermodynamic basis of the binding interactions of the extracellular ligands and intracellular effector proteins is essential to understand the workings of these remarkable nanomachines. In this review, we describe how isothermal titration calorimetry (ITC) can be effectively used to gain valuable insights into the thermodynamic signatures (enthalpy, entropy, affinity, and stoichiometry), which would be most useful for drug discovery studies, considering that more than 30% of the current drugs target membrane proteins. This article is part of a Special Issue entitled: Structural and biophysical characterisation of membrane protein-ligand binding. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. IMPEDANCE METHOD OF MEASURING OF THE TITRATABLE ACIDITY OF YOGURT

    Directory of Open Access Journals (Sweden)

    Miroslav Vasilev

    2016-10-01

    Full Text Available In the present work are analyzed studies related to changes in the active impedance component of the dairy environment caused by the flow of lactic fermentation and coagulation of casein in milk. The aim of this work was to determine the relationship between the relative change of titratable acidity and the relative change of active impedance component of the dairy environment with lactic fermentation, causing coagulation of the casein in milk. . The data were interpolated with cubic spline, visualizing how when the fat content increases, the electrical resistance increases too. All data, collected during the tests would complement and be used for solving the optimization problem to determine the time of completion of the coagulation in future work.

  16. Biophysical characterization of antibodies with isothermal titration calorimetry

    Directory of Open Access Journals (Sweden)

    Verna Frasca

    2016-07-01

    Full Text Available Antibodies play a key role in the immune response. Since antibodies bind antigens with high specificity and tight affinity, antibodies are an important reagent in experimental biology, assay development, biomedical research and diagnostics. Monoclonal antibodies are therapeutic drugs and used for vaccine development. Antibody engineering, biophysical characterization, and structural data have provided a deeper understanding of how antibodies function, and how to make better drugs. Isothermal titration calorimetry (ITC is a label-free binding assay, which measures affinity, stoichiometry, and binding thermodynamics for biomolecular interactions. When thermodynamic data are used together with structural and kinetic data from other assays, a complete structure-activity-thermodynamics profile can be constructed. This review article describes ITC, and discusses several applications on how data from ITC provides insights into how antibodies function, guide antibody engineering, and aid design of new therapeutic drugs.

  17. Determination of Dimethylallylamine by Titration in Nonaqueous Solvent

    Institute of Scientific and Technical Information of China (English)

    LIU Li-hua; GONG Zhu-qing; ZHENG Ya-jie

    2004-01-01

    The content of dimethylallylamine was determined using glacial acetic acid as solvent, acetic-formic mixture as an anhydrite, perchloric acid-glacial acetic acid as titrant, and 1% crystal violet in acetic acid as indicator in the presence of methylamine and dimethylamine The influences of inert constituents and water on the titration were investigated, and a complete analytical method was determined. The results showed that the determination error of total amines increased with water increasing, while the effect of water on the determination of dimethylallylamine was little when the amount of water was within 5%, the relative error was generally within 1%, and that the end-point was acutely when about 10% chloroform was added. Compared with gas chromatography, this method is simple, convenient and accurate.

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

    Science.gov (United States)

    Wang, Bin; Jia, Yuan; Lin, Qiao

    2016-04-15

    Isothermal titration calorimetry (ITC) directly measures heat evolved in a chemical reaction to determine equilibrium binding properties of biomolecular systems. Conventional ITC instruments are expensive, use complicated design and construction, and require long analysis times. Microfabricated calorimetric devices are promising, although they have yet to allow accurate, quantitative ITC measurements of biochemical reactions. This paper presents a microfabrication-based approach to integrated, quantitative ITC characterization of biomolecular interactions. The approach integrates microfabricated differential calorimetric sensors with microfluidic titration. Biomolecules and reagents are introduced at each of a series of molar ratios, mixed, and allowed to react. The reaction thermal power is differentially measured, and used to determine the thermodynamic profile of the biomolecular interactions. Implemented in a microdevice featuring thermally isolated, well-defined reaction volumes with minimized fluid evaporation as well as highly sensitive thermoelectric sensing, the approach enables accurate and quantitative ITC measurements of protein-ligand interactions under different isothermal conditions. Using the approach, we demonstrate ITC characterization of the binding of 18-Crown-6 with barium chloride, and the binding of ribonuclease A with cytidine 2'-monophosphate within reaction volumes of approximately 0.7 µL and at concentrations down to 2mM. For each binding system, the ITC measurements were completed with considerably reduced analysis times and material consumption, and yielded a complete thermodynamic profile of the molecular interaction in agreement with published data. This demonstrates the potential usefulness of our approach for biomolecular characterization in biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Do Intermediate Radiation Doses Contribute to Late Rectal Toxicity? An Analysis of Data From Radiation Therapy Oncology Group Protocol 94-06

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Susan L., E-mail: sltucker@mdanderson.org [Department of Bioinformatics and Computational Biology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Dong, Lei [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Michalski, Jeff M. [Department of Radiation Oncology, Washington University, St. Louis, MO (United States); Bosch, Walter R. [Department of Radiation Oncology, Washington University, St. Louis, MO (United States); Image-Guided Therapy QA Center, Washington University, St. Louis, MO (United States); Winter, Kathryn [American College of Radiology, Philadelphia, PA (United States); Cox, James D. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Purdy, James A. [Department of Radiation Oncology, University of California Davis Medical Center, Sacramento, CA (United States); Mohan, Radhe [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX (United States)

    2012-10-01

    Purpose: To investigate whether the volumes of rectum exposed to intermediate doses, from 30 to 50 Gy, contribute to the risk of Grade {>=}2 late rectal toxicity among patients with prostate cancer receiving radiotherapy. Methods and Materials: Data from 1009 patients treated on Radiation Therapy Oncology Group protocol 94-06 were analyzed using three approaches. First, the contribution of intermediate doses to a previously published fit of the Lyman-Kutcher-Burman (LKB) normal tissue complication probability (NTCP) model was determined. Next, the extent to which intermediate doses provide additional risk information, after taking the LKB model into account, was investigated. Third, the proportion of rectum receiving doses higher than a threshold, VDose, was computed for doses ranging from 5 to 85 Gy, and a multivariate Cox proportional hazards model was used to determine which of these parameters were significantly associated with time to Grade {>=}2 late rectal toxicity. Results: Doses <60 Gy had no detectable impact on the fit of the LKB model, as expected on the basis of the small estimate of the volume parameter (n = 0.077). Furthermore, there was no detectable difference in late rectal toxicity among cohorts with similar risk estimates from the LKB model but with different volumes of rectum exposed to intermediate doses. The multivariate Cox proportional hazards model selected V75 as the only value of VDose significantly associated with late rectal toxicity. Conclusions: There is no evidence from these data that intermediate doses influence the risk of Grade {>=}2 late rectal toxicity. Instead, the critical doses for this endpoint seem to be {>=}75 Gy. It is hypothesized that cases of Grade {>=}2 late rectal toxicity occurring among patients with V75 less than approximately 12% may be due to a 'background' level of risk, likely due mainly to biological factors.

  20. Abundance and distribution of major groups of diazotrophic cyanobacteria and their potential contribution to N₂ fixation in the tropical Atlantic Ocean.

    Science.gov (United States)

    Goebel, Nicole L; Turk, Kendra A; Achilles, Katherine M; Paerl, Ryan; Hewson, Ian; Morrison, Amanda E; Montoya, Joseph P; Edwards, Christopher A; Zehr, Jonathan P

    2010-12-01

    The abundances of six N₂-fixing cyanobacterial phylotypes were profiled at 22 stations across the tropical Atlantic Ocean during June 2006, and used to model the contribution of the diazotrophs to N₂ fixation. Diazotroph abundances were measured by targeting the nifH gene of Trichodesmium, unicellular groups A, B, C (UCYN-A, UCYN-B and UCYN-C), and diatom-cyanobiont symbioses Hemiaulus-Richelia, Rhizosolenia-Richelia and Chaetoceros-Calothrix. West to east gradients in temperature, salinity and nutrients [NO₃⁻ + NO₂⁻, PO₄³⁻, Si(OH)₄] showed the influence of the Amazon River plume and its effect on the distributions of the diazotrophs. Trichodesmium accounted for more than 93% of all nifH genes detected, dominated the warmer waters of the western Atlantic, and was the only diazotroph detected at the equatorial upwelling station. UCYN-A was the next most abundant (> 5% of all nifH genes) and dominated the cooler waters of the eastern Atlantic near the Cape Verde Islands. UCYN-C was found at a single depth (200 m) of high salinity and low temperature and nutrients, whereas UCYN-B cells were widespread but in very low abundance (6.1 × 10¹ ± 4.6 × 10² gene copies l⁻¹). The diatom-cyanobionts were observed primarily in the western Atlantic within or near the high Si(OH)₄ input of the Amazon River plume. Overall, highest diazotroph abundances were observed at the surface and declined with depth, except for some subsurface peaks in Trichodesmium, UCYN-B and UCYN-A. Modelled contributions of Trichodesmium, UCYN-B and UCYN-A to total N₂ fixation suggested that Trichodesmium had the largest input, except for the potential of UCYN-A at the Cape Verde Islands.

  1. Estimation of environment-related properties of chemicals for design of sustainable processes: development of group-contribution+ (GC+) property models and uncertainty analysis.

    Science.gov (United States)

    Hukkerikar, Amol Shivajirao; Kalakul, Sawitree; Sarup, Bent; Young, Douglas M; Sin, Gürkan; Gani, Rafiqul

    2012-11-26

    The aim of this work is to develop group-contribution(+) (GC(+)) method (combined group-contribution (GC) method and atom connectivity index (CI) method) based property models to provide reliable estimations of environment-related properties of organic chemicals together with uncertainties of estimated property values. For this purpose, a systematic methodology for property modeling and uncertainty analysis is used. The methodology includes a parameter estimation step to determine parameters of property models and an uncertainty analysis step to establish statistical information about the quality of parameter estimation, such as the parameter covariance, the standard errors in predicted properties, and the confidence intervals. For parameter estimation, large data sets of experimentally measured property values of a wide range of chemicals (hydrocarbons, oxygenated chemicals, nitrogenated chemicals, poly functional chemicals, etc.) taken from the database of the US Environmental Protection Agency (EPA) and from the database of USEtox is used. For property modeling and uncertainty analysis, the Marrero and Gani GC method and atom connectivity index method have been considered. In total, 22 environment-related properties, which include the fathead minnow 96-h LC(50), Daphnia magna 48-h LC(50), oral rat LD(50), aqueous solubility, bioconcentration factor, permissible exposure limit (OSHA-TWA), photochemical oxidation potential, global warming potential, ozone depletion potential, acidification potential, emission to urban air (carcinogenic and noncarcinogenic), emission to continental rural air (carcinogenic and noncarcinogenic), emission to continental fresh water (carcinogenic and noncarcinogenic), emission to continental seawater (carcinogenic and noncarcinogenic), emission to continental natural soil (carcinogenic and noncarcinogenic), and emission to continental agricultural soil (carcinogenic and noncarcinogenic) have been modeled and analyzed. The application

  2. Contribuições da poética social à pesquisa em psicoterapia de grupo Contributions of social poesis to group psychotherapy research

    Directory of Open Access Journals (Sweden)

    Carla Guanaes

    2008-08-01

    Full Text Available Esse artigo tem por objetivo apresentar algumas contribuições do construcionismo social e da poética social ao entendimento da psicoterapia de grupo e de sua investigação científica. O construcionismo social se define como uma forma alternativa de inteligibilidade em ciência, que privilegia a compreensão do modo como as pessoas constroem sentidos sobre o mundo e sobre si mesmas em suas práticas discursivas. Coerente com essa perspectiva, a poética social caracteriza uma prática de pesquisa útil à investigação dos processos conversacionais, enfatizando a centralidade do pesquisador na construção de sentidos sobre seu objeto de estudo. Nesse artigo, buscamos demonstrar como estas perspectivas podem sustentar uma prática sistemática de pesquisa sobre a psicoterapia de grupo. Para tanto, apresenta os passos metodológicos desenvolvidos em um estudo acerca de um grupo em saúde mental, demonstrando como esses permitiram compreender o processo conversacional por meio do qual o próprio grupo se constituiu como um recurso terapêutico.The objective of this article is to describe some contributions of social constructionism and social poesis in the description of group psychotherapy and its scientific investigation. Social constructionism is an alternative form of intelligibility in science, which focuses on the comprehension of the way people make sense of the world and of themselves in their discursive practices. Concurrent with this perspective, social poesis can be described as a research practice that is useful in investigating the conversational processes, emphasizing the centrality of the researcher in the construction of meanings about its object of study. In this article, we aim to describe how these perspectives can sustain a systematic research practice of group psychotherapy. Thus, we describe some methodological steps developed in a study about a group in a mental health setting, showing how they helped us to comprehend

  3. Quick titration of pergolide in cotreatment with domperidone is safe and effective

    NARCIS (Netherlands)

    Jansen, PAF; Herings, RMC; Samson, MM; Schuurmans-Daemen, LMPJ; Hovestadt, A; Verhaar, HJJ; Van Laar, T; de Vreede, P.

    2001-01-01

    The purpose of the study was to analyze efficacy and safety of quick pergolide titration combined with domperidone. In an open-label prospective study, pergolide was titrated in 16 days to a maximum of 3 mg/d doses as adjunctive treatment to L-Dopa in 10 elderly patients with Parkinson's disease. Si

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

    Science.gov (United States)

    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,…

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

    NARCIS (Netherlands)

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

    1979-01-01

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

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

    NARCIS (Netherlands)

    Bos, M.; Linden, van der W.E.

    1996-01-01

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

  7. Quick titration of pergolide in cotreatment with domperidone is safe and effective

    NARCIS (Netherlands)

    Jansen, PAF; Herings, RMC; Samson, MM; Schuurmans-Daemen, LMPJ; Hovestadt, A; Verhaar, HJJ; Van Laar, T; de Vreede, P.

    2001-01-01

    The purpose of the study was to analyze efficacy and safety of quick pergolide titration combined with domperidone. In an open-label prospective study, pergolide was titrated in 16 days to a maximum of 3 mg/d doses as adjunctive treatment to L-Dopa in 10 elderly patients with Parkinson's disease.

  8. Study and Application of a New On—Line Titration Technique

    Institute of Scientific and Technical Information of China (English)

    朱建育; 施利毅; 等

    2002-01-01

    A new on-line titration method and device based on a new technique-continuous flow titration is described.By the means of electronically controlled switching of a solenoid valve,the main component of the system,the equivalent point of the titration is easily determined.Several kinds of mixing tools were examined.whereby a self-made mixing chamer with minimum volume gave best results and was therefore used in the dveice,The error of the titration is within 0.2% and the relative standard deviation(RSD) is below 1.2%,The results show no difference compared with a commercial device,meanwhile the new on-line titration system is cheaper and fully automated and thus easy to hand and less slovent consumption.

  9. SPECIAL CONSIDERATIONS REGARDING WARFARIN DOSE TITRATION IN PATIENTS WITH ATRIAL FIBRILLATION DEPENDING ON CLINICAL FACTORS

    Directory of Open Access Journals (Sweden)

    E. L. Artanova

    2011-01-01

    Full Text Available Aim. To study the relations of clinical characteristics and individual warfarin dose titration in patients with atrial fibrillation. Material and methods. Period of warfarin dose titration was analyzed in 68 patients with atrial fibrillation due to ischemic heart disease. Adjusted warfarin dose in milligram, duration of dose titration in days and maximal international normalized ratio (INR were taken into account. Sex, age, history of myocardial infarction and stroke, concomitant diseases, amiodarone therapy were considered among clinical characteristics. Results. Adjusted warfarin dose was significantly higher in obesity , and it was lower in case of experienced myocardial infarction. The INR highest levels and maximal amplitudes of its fluctuations were observed in patients with thyroid gland nodes and smokers. Period of warfarin dose titration was longer in patients treated with amiodarone. Conclusion. Warfarin dose titration in patients with atrial fibrillation depends on the presence of myocardial infarction, obesity , thyroid nodular changes, smoking and amiodarone treatment.

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

    Science.gov (United States)

    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.

  11. Thermodynamics of the complexation of Hg(II) by cysteinyl peptide ligands using isothermal titration calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ngu-Schwemlein, Maria, E-mail: Schwemleinmn@wssu.edu [Department of Chemistry, Winston-Salem State University, Winston-Salem, NC 27110 (United States); Merle, John K.; Healy, Patrick; Schwemlein, Stefanie; Rhodes, Sade [Department of Chemistry, Winston-Salem State University, Winston-Salem, NC 27110 (United States)

    2009-12-10

    The present study was undertaken to better understand the complexation of mercury (II) by cysteine, histidine, tryptophan, and their di- and tri-peptides. Their mercury (II) binding affinities and associated thermodynamic parameters are evaluated by isothermal titration calorimetry. Cysteine S-donor atoms form the strongest complexes, which can be attributed to a more exothermic Hg-S soft acid and soft base interaction. These thiol S-donor peptide ligands show two sequential binding for mercury (II). Their stability constants for the first binding (10{sup 8} M{sup -1} to >10{sup 10} M{sup -1}) are largely due to favorable contribution of the enthalpy term to the free energy of complexation. As more mercury (II) ions are added, this enthalpy contribution decreases and the free energy of the second binding (10{sup 5} M{sup -1} to 10{sup 6} M{sup -1}) is partially compensated by the entropy term. The dependency of the fluorescence intensity for these peptides on mercury (II) concentration shows two different Stern-Volmer plots, which corroborates the calorimetric data and supports the formation of two types of stable complexes.

  12. Predicting CO2 Solubility in Imidazole Ionic Liquids for Use in Absorption Refrigeration Systems by Using the Group Contribution Equation of State Method

    Science.gov (United States)

    Wu, Wei-Dong; Wu, Jun; Hou, Yong; Su, Lin; Zhang, Hua

    2017-09-01

    Traditional absorption refrigeration such as H2O-LiBr- and NH3-H2O-based refrigeration has limited applications because of several issues, including crystallization, corrosion, and large volume. CO2-ionic liquids (ILs) as new absorption working pairs were investigated in this study. The objective was to use the group contribution equation of state (GC-EOS) method to predict the solubilities of binary systems containing high-pressure CO2-imidazole bis(trifluoromethanesulfonimide) ILs and to investigate the applicability and accuracy of the GC-EOS model. The results showed that at pressures up to 11.0 MPa and temperatures of 273 K to 400 K, the CO2 solubility in the ILs increased with increasing system pressure but decreased with increasing temperature, and its variation rate was lower at higher pressures or temperatures. Also, CO2 solubility increased in the order of [emim][Tf2N] families resulted in higher CO_{2 } solubility. The model prediction of CO2 solubility in the four different ILs showed reasonable consistency with the corresponding experimental results from the literature; the largest deviation was 5.7 % for CO2-[emim][Tf2N]. Therefore, it can be concluded that the GC-EOS model is a promising theoretical solution that can be used to search for suitable CO2-IL working pairs for absorption refrigeration systems.

  13. Development of a group contribution method for estimating free energy of peptides in a dodecane-water system via molecular dynamic simulations.

    Science.gov (United States)

    Mora Osorio, Camilo Andrés; González Barrios, Andrés Fernando

    2016-12-07

    Calculation of the Gibbs free energy changes of biological molecules at the oil-water interface is commonly performed with Molecular Dynamics simulations (MD). It is a process that could be performed repeatedly in order to find some molecules of high stability in this medium. Here, an alternative method of calculation has been proposed: a group contribution method (GCM) for peptides based on MD of the twenty classic amino acids to obtain free energy change during the insertion of any peptide chain in water-dodecane interfaces. Multiple MD of the twenty classic amino acids located at the interface of rectangular simulation boxes with a dodecane-water medium were performed. A GCM to calculate the free energy of entire peptides is then proposed. The method uses the summation of the Gibbs free energy of each amino acid adjusted in function of its presence or absence in the chain as well as its hydrophobic characteristics. Validation of the equation was performed with twenty-one peptides all simulated using MD in dodecane-water rectangular boxes in previous work, obtaining an average relative error of 16%.

  14. CONTRIBUIÇÕES DE GRUPO DE ESTUDOS SOBRE MATEMÁTICA EM CONHECIMENTOS DE PROFESSORAS. CONTRIBUTIONS OF A MATHEMATICS STUDY GROUP FOR TEACHING KNOWLEDGE

    Directory of Open Access Journals (Sweden)

    Silva, Sandra Aparecida Fraga da

    2012-05-01

    participated. In this group, the teachers respected each other, listened and were listened in their victories and anxieties, gave opinion, proposed ideas and contributed for the construction of different knowledge. This behavior influenced the teachers’ learning and attitudes towards mathematics, and this resonated in their classroom practices. We got evidences of improvement and learning of two sorts of knowledge: of mathematics content and of pedagogical mathematics. From the mathematical content knowledge learned we highlight problem solving involving the four operations. And from the pedagogical mathematical knowledge we highlight what was evidenced in actions in the study group. We noticed that a different work with in-service teacher training in context, in a group where we had a peer critical environment, influenced and involved all its members.

  15. Provenance and sedimentary environments of the Proterozoic São Roque Group, SE-Brazil: Contributions from petrography, geochemistry and Sm-Nd isotopic systematics of metasedimentary rocks

    Science.gov (United States)

    Henrique-Pinto, R.; Janasi, V. A.; Tassinari, C. C. G.; Carvalho, B. B.; Cioffi, C. R.; Stríkis, N. M.

    2015-11-01

    The Proterozoic metasedimentary sequences exposed in the São Roque Domain (Apiaí Terrane, Ribeira Belt, southeast Brazil) consist of metasandstones and meta-felspathic wackes with some volcanic layers of within-plate geochemical signature (Boturuna Formation), a passive margin turbidite sequence of metawackes and metamudstones (Piragibu Formation), and volcano-sedimentary sequences with MORB-like basalts (Serra do Itaberaba Group; Pirapora do Bom Jesus Formation). A combination of zircon provenance studies in metasandstones, whole-rock geochemistry and Sm-Nd isotopic systematics in metamudstones was used to understand the provenance and tectonic significance of these sequences, and their implications to the evolution of the Precambrian crust in the region. Whole-rock geochemistry of metamudstones, dominantly from the Piragibu Formation, points to largely granitic sources (as indicated for instance by LREE-rich moderately fractionated REE patterns and subtle negative Eu anomalies) with some mafic contribution (responding for higher contents of Fe2O3, MgO, V, and Cr) and were subject to moderate weathering (CIA - 51 to 85). Sm-Nd isotope data show three main peaks of Nd TDM ages at ca. 1.9, 2.1 and 2.4 Ga; the younger ages define an upper limit for the deposition of the unit, and reflect greater contributions from sources younger than the >2.1 Ga basement. The coincident age peaks of Nd TDM and U-Pb detrital zircons at 2.1-2.2 Ga and 2.4-2.5 Ga, combined with the possible presence of a small amount of zircons derived from mafic (gabbroid) sources with the same ages, as indicated by a parallel LA-ICPMS U-Pb dating study in metapsammites, are suggestive that these were major periods of crustal growth in the sources involving not only crust recycling but also some juvenile addition. A derivation from similar older Proterozoic sources deposited in a passive margin basin is consistent with the main sedimentary sequences in the São Roque Domain being broadly coeval and

  16. Patient-led versus physician-led titration of insulin glargine in patients with uncontrolled type 2 diabetes: a randomized multinational ATLAS study.

    Science.gov (United States)

    Garg, Satish K; Admane, Karim; Freemantle, Nick; Odawara, Masato; Pan, Chang-Yu; Misra, Anoop; Jarek-Martynowa, Iwona R; Abbas-Raza, Syed; Mirasol, Roberto C; Perfetti, Riccardo

    2015-02-01

    Self-adjustment of insulin dose is commonly practiced in Western patients with type 2 diabetes but is usually not performed in Asian patients. This multinational, 24-week, randomized study compared patient-led with physician-led titration of once-daily insulin glargine in Asian patients with uncontrolled type 2 diabetes who were on 2 oral glucose-lowering agents. Patient-led (n = 275) or physician-led (n = 277) subjects followed the same dose-titration algorithm guided by self-monitored fasting blood glucose (FBG; target, 110 mg/dL [6.1 mmol/L]). The primary endpoint was change in mean glycated hemoglobin (HbA1c) at week 24 in the patient-led versus physician-led titration groups. Patient-led titration resulted in a significantly higher drop in HbA1c value at 24 weeks when compared with physician-led titration (-1.40% vs. -1.25%; mean difference, -0.15; 95% confidence interval, -0.29 to 0.00; P = .043). Mean decrease in FBG was greatest in the patient-led group (-2.85 mmol/L vs. -2.48 mmol/L; P = .001). The improvements in HbA1c and FBG were consistent across countries, with similar improvements in treatment satisfaction in both groups. Mean daily insulin dose was higher in the patient-led group (28.9 units vs. 22.2 units; P<.001). Target HbA1c of <7.0% without severe hypoglycemia was achieved in 40.0% and 32.9% in the patient-led and physician-led groups, respectively (P = .086). Severe hypoglycemia was not different in the 2 groups (0.7%), with an increase in nocturnal and symptomatic hypoglycemia in the patient-led arm. Patient-led insulin glargine titration achieved near-target blood glucose levels in Asian patients with uncontrolled type 2 diabetes who were on 2 oral glucose-lowering drugs, demonstrating that Asian patients can self-uptitrate insulin dose effectively when guided.

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

    Science.gov (United States)

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2014-04-04

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

  18. Characterization of membrane protein interactions by isothermal titration calorimetry.

    Science.gov (United States)

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

    2014-10-23

    Understanding the structure, folding, and interaction of membrane proteins requires experimental tools to quantify the association of transmembrane (TM) helices. Here, we introduce isothermal titration calorimetry (ITC) to measure integrin αIIbβ3 TM complex affinity, to study the consequences of helix-helix preorientation in lipid bilayers, and to examine protein-induced lipid reorganization. Phospholipid bicelles served as membrane mimics. The association of αIIbβ3 proceeded with a free energy change of -4.61±0.04kcal/mol at bicelle conditions where the sampling of random helix-helix orientations leads to complex formation. At bicelle conditions that approach a true bilayer structure in effect, an entropy saving of >1kcal/mol was obtained from helix-helix preorientation. The magnitudes of enthalpy and entropy changes increased distinctly with bicelle dimensions, indicating long-range changes in bicelle lipid properties upon αIIbβ3 TM association. NMR spectroscopy confirmed ITC affinity measurements and revealed αIIbβ3 association and dissociation rates of 4500±100s(-1) and 2.1±0.1s(-1), respectively. Thus, ITC is able to provide comprehensive insight into the interaction of membrane proteins. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Enzyme kinetics determined by single-injection isothermal titration calorimetry.

    Science.gov (United States)

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

    2015-04-01

    The purposes of this paper are (a) to examine the effect of calorimeter time constant (τ) on heat rate data from a single enzyme injection into substrate in an isothermal titration calorimeter (ITC), (b) to provide information that can be used to predict the optimum experimental conditions for determining the rate constant (k2), Michaelis constant (KM), and enthalpy change of the reaction (ΔRH), and (c) to describe methods for evaluating these parameters. We find that KM, k2 and ΔRH can be accurately estimated without correcting for the calorimeter time constant, τ, if (k2E/KM), where E is the total active enzyme concentration, is between 0.1/τ and 1/τ and the reaction goes to at least 99% completion. If experimental conditions are outside this domain and no correction is made for τ, errors in the inferred parameters quickly become unreasonable. A method for fitting single-injection data to the Michaelis-Menten or Briggs-Haldane model to simultaneously evaluate KM, k2, ΔRH, and τ is described and validated with experimental data. All four of these parameters can be accurately inferred provided the reaction time constant (k2E/KM) is larger than 1/τ and the data include enzyme saturated conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Hot Biological Catalysis: Isothermal Titration Calorimetry to Characterize Enzymatic Reactions

    Science.gov (United States)

    Mazzei, Luca; Ciurli, Stefano; Zambelli, Barbara

    2014-01-01

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

  1. Effect of a stirring process in an isothermal titration microcalorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Socorro, F.; Nuez, I. de la; Alvarez, L.; Rodriguez de Rivera, M

    2004-10-01

    In this paper, it is analysed the way in which the thermodynamic results obtained in an isothermal titration microcalorimeter, with continuous injection of a liquid and a variable mass are affected. Two aspects are presented, the first one refers to a variation in the baseline that takes place when the liquid mass is increased in the laboratory cell, this variation is due to the change in the thermal coupling between the stirrer and its contact with the thermostat. The second aspect is the analysis of the effect of the stirring process and the injection velocity on the homogenization of the remaining mixture in the laboratory cell. The aim of the study of these two previous aspects is to increase the accuracy of the thermodynamic measures carried out. The variation of the baseline affects in a percentage from 1 to 2% of the total energy developed. It is also shown the necessity of a stirring process according to the injection velocity in order to obtain a homogeneous mixture at every instant. This fact allows to carry out a deconvolution of the calorimetric signal and to obtain directly the power developed in the mixture process in terms of the amount of mixed substance [Meas. Sci. Technol. 1 (1990) pp. 1285-1290; J. Thermal Analysis 41 (1994) pp. 1385-1392].

  2. Survey of the year 2008: applications of isothermal titration calorimetry.

    Science.gov (United States)

    Falconer, Robert J; Penkova, Anita; Jelesarov, Ilian; Collins, Brett M

    2010-01-01

    Isothermal titration calorimetry (ITC) is a fast, accurate and label-free method for measuring the thermodynamics and binding affinities of molecular associations in solution. Because the method will measure any reaction that results in a heat change, it is applicable to many different fields of research from biomolecular science, to drug design and materials engineering, and can be used to measure binding events between essentially any type of biological or chemical ligand. ITC is the only method that can directly measure binding energetics including Gibbs free energy, enthalpy, entropy and heat capacity changes. Not only binding thermodynamics but also catalytic reactions, conformational rearrangements, changes in protonation and molecular dissociations can be readily quantified by performing only a small number of ITC experiments. In this review, we highlight some of the particularly interesting reports from 2008 employing ITC, with a particular focus on protein interactions with other proteins, nucleic acids, lipids and drugs. As is tradition in these reviews we have not attempted a comprehensive analysis of all 500 papers using ITC, but emphasize those reports that particularly captured our interest and that included more thorough discussions we consider exemplify the power of the technique and might serve to inspire other users.

  3. Who is who in the understory: the contribution of resident and transitory groups of species to plant richness in forest assemblages

    Directory of Open Access Journals (Sweden)

    JulianaSilva Gomes-Westphalen

    2012-09-01

    Full Text Available The forest understory is made up of resident and transitory species and can be much richer than the canopy. With the purpose to describe the contribution of these groups to the woody understory, five Atlantic Forest fragments were selected and studied in Northeastern Brazil. In order to analyze the understory’s structure, the sample included woody individuals with circumference at breast height (CBH smaller than 15cm and circumference at ground level (CGL greater than 3cm, regardless of height. The recorded species were quantified and classified into functional stratification categories (resident and transitory, and the floristic similarity between the understory and the tree stratum was calculated. Species’ importance in the understory was analyzed by height and total natural regeneration classes based on a regeneration index. The understory was richer in species (median=63.8, SD=21.72, n=5 fragments than the tree stratum (43.8, 18.14, 5, and the similarity between these components was relatively high (median=0.54, SD=0.09. The results also showed that the studied understory in the forest fragments was mainly composed by transitory species (median=67.01%, SD=3.76, that were well distributed among height classes and had the highest densities, which may favor their future presence in the canopy’s structure and composition. The typical understory species were grouped into two strata: the lower understory, made up of species that generally do not reach more than 4m in height (mostly species from families Piperaceae, Rubiaceae and Melastomataceae; and the upper understory, with intermediate heights between the lower understory and the canopy, but with average heights that were not higher than 10m (mainly of species from families Anonnaceae, Clusiaceae and Myrtaceae. These families’ richness was commonly used as an indicator of the vegetation’s successional stage; however, such results must be seen with caution as they show that these

  4. A conserved UDP-glucose dehydrogenase encoded outside the hasABC operon contributes to capsule biogenesis in group A Streptococcus.

    Science.gov (United States)

    Cole, Jason N; Aziz, Ramy K; Kuipers, Kirsten; Timmer, Anjuli M; Nizet, Victor; van Sorge, Nina M

    2012-11-01

    Group A Streptococcus (GAS) is a human-specific bacterial pathogen responsible for serious morbidity and mortality worldwide. The hyaluronic acid (HA) capsule of GAS is a major virulence factor, contributing to bloodstream survival through resistance to neutrophil and antimicrobial peptide killing and to in vivo pathogenicity. Capsule biosynthesis has been exclusively attributed to the ubiquitous hasABC hyaluronan synthase operon, which is highly conserved across GAS serotypes. Previous reports indicate that hasA, encoding hyaluronan synthase, and hasB, encoding UDP-glucose 6-dehydrogenase, are essential for capsule production in GAS. Here, we report that precise allelic exchange mutagenesis of hasB in GAS strain 5448, a representative of the globally disseminated M1T1 serotype, did not abolish HA capsule synthesis. In silico whole-genome screening identified a putative HasB paralog, designated HasB2, with 45% amino acid identity to HasB at a distant location in the GAS chromosome. In vitro enzymatic assays demonstrated that recombinant HasB2 is a functional UDP-glucose 6-dehydrogenase enzyme. Mutagenesis of hasB2 alone slightly decreased capsule abundance; however, a ΔhasB ΔhasB2 double mutant became completely acapsular. We conclude that HasB is not essential for M1T1 GAS capsule biogenesis due to the presence of a newly identified HasB paralog, HasB2, which most likely resulted from gene duplication. The identification of redundant UDP-glucose 6-dehydrogenases underscores the importance of HA capsule expression for M1T1 GAS pathogenicity and survival in the human host.

  5. 沉淀滴定的林邦滴定曲线方程%Ringbom titration curve equation of precipitation titration

    Institute of Scientific and Technical Information of China (English)

    乔成立; 李文新

    2014-01-01

    Ionic strength effect,acid effect,precipitation effect and ligand effect were identified as side reactions of the main reaction,Ringbom titration curve equation of precipitation titration was derived by means of material balance, conditional stability constant and titration scores,etc,which can lay a solid foundation for researching precipitation titration analysis theory on the basis of Ringbom titration curve equation.%把离子强度效应、酸效应、沉淀效应、配位效应等看作是主反应发生的副反应,通过物料平衡、条件稳定常数和滴定分数等推导出沉淀滴定的林邦滴定曲线方程,为用林邦滴定曲线方程研究沉淀滴定分析理论打下坚实的基础。

  6. Titration Calorimetry Applied to the Thermokinetics Study of Consecutive First-order Reactions

    Institute of Scientific and Technical Information of China (English)

    SHI Jing-Yan; LI Jie; WANG Zhi-Yong; LIU Yu-Wen; WANG Cun-Xin

    2008-01-01

    The thermokinetic mathematical models for consecutive first-order reactions in titration period and the stopped-titration reaction period were proposed for titration calorimetry, based on which, thermodynamic parameters (reaction enthalpies, △rHm1 and △rHm2) and kinetic parameters (rate constants, k1 and k2) of the consecutive first-order reactions could be obtained by directly simulating the calorimetric curve from a single experiment with the method of nonlinear least squares regression (NLLS).The reliability of the model has been verified by investigating the reaction of the saponification of diethyl succinate in an aqueous ethanol solvent.

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

    Science.gov (United States)

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

    2009-01-01

    We have performed a detailed study of the thermodynamics of the titration process in an isothermal titration calorimeter with full cells. We show that the relationship between the enthalpy and the heat measured is better described in terms of the equation Δ H = Winj + Q (where Winj is the work necessary to carry out the titration) than in terms of ΔH = Q. Moreover, we show that the heat of interaction between two components is related to the partial enthalpy of interaction at infinite dilution of the titrant component, as well as to its partial volume of interaction at infinite dilution. PMID:20054472

  8. Vascular Endothelial Growth Factor Peptide Ligands Explored by Competition Assay and Isothermal Titration Calorimetry.

    Science.gov (United States)

    Reille-Seroussi, Marie; Gaucher, Jean-François; Desole, Claudia; Gagey-Eilstein, Nathalie; Brachet, Franck; Broutin, Isabelle; Vidal, Michel; Broussy, Sylvain

    2015-08-25

    The v114* cyclic peptide has been identified as a tight vascular endothelial growth factor (VEGF) ligand. Here we report on the use of isothermal titration calorimetry (ITC), 96-well plate competition assay, and circular dichroism (CD) to explore the binding determinants of a new set of related peptides. Anti-VEGF antibodies are currently used in the clinic for regulating angiogenesis in cancer and age-related macular degeneration treatment. In this context, our aim is to develop smaller molecular entities with high affinity for the growth factor by a structure activity relationship approach. The cyclic disulfide peptide v114* was modified in several ways, including truncation, substitution, and variation of the size and nature of the cycle. The results indicated that truncation or substitution of the four N-terminal amino acids did not cause severe loss in affinity, allowing potential peptide labeling. Increase of the cycle size or substitution of the disulfide bridge with a thioether linkage drastically decreased the affinity, due to an enthalpy penalty. The leucine C-terminal residue positively contributed to affinity. Cysteine N-terminal acetylation induced favorable ΔΔG° and ΔΔH° of binding, which correlated with free peptide CD spectra changes. We also propose a biochemical model to extrapolate Ki from IC50 values measured in the displacement assay. These calculated Ki correlate well with the Kd values determined by extensive direct and reverse ITC measurements.

  9. Isothermal titration calorimetry in nanoliter droplets with subsecond time constants.

    Science.gov (United States)

    Lubbers, Brad; Baudenbacher, Franz

    2011-10-15

    We reduced the reaction volume in microfabricated suspended-membrane titration calorimeters to nanoliter droplets and improved the sensitivities to below a nanowatt with time constants of around 100 ms. The device performance was characterized using exothermic acid-base neutralizations and a detailed numerical model. The finite element based numerical model allowed us to determine the sensitivities within 1% and the temporal dynamics of the temperature rise in neutralization reactions as a function of droplet size. The model was used to determine the optimum calorimeter design (membrane size and thickness, junction area, and thermopile thickness) and sensitivities for sample volumes of 1 nL for silicon nitride and polymer membranes. We obtained a maximum sensitivity of 153 pW/(Hz)(1/2) for a 1 μm SiN membrane and 79 pW/(Hz)(1/2) for a 1 μm polymer membrane. The time constant of the calorimeter system was determined experimentally using a pulsed laser to increase the temperature of nanoliter sample volumes. For a 2.5 nanoliter sample volume, we experimentally determined a noise equivalent power of 500 pW/(Hz)(1/2) and a 1/e time constant of 110 ms for a modified commercially available infrared sensor with a thin-film thermopile. Furthermore, we demonstrated detection of 1.4 nJ reaction energies from injection of 25 pL of 1 mM HCl into a 2.5 nL droplet of 1 mM NaOH.

  10. Relative contributions of crust and mantle to the origin of the Bijli Rhyolite in a palaeoproterozoic bimodal volcanic sequence (Dongargarh Group), central India

    Indian Academy of Sciences (India)

    Sarajit Sensarma; S Hoernes; Dhruba Mukhopadhyay

    2004-12-01

    New mineralogical, bulk chemical and oxygen isotope data on the Palaeoproterozoic Bijli Rhyolite, the basal unit of a bimodal volcanic sequence (Dongargarh Group) in central India, and one of the most voluminous silicic volcanic expressions in the Indian Shield, are presented. The Bijli Rhyolite can be recognized as a poorly sorted pyroclastic deposit, and comprises of phenocrystic K-feldspar + albite ± anorthoclase set in fine-grained micro-fragmental matrix of quartz-feldsparsericite- chlorite-iron-oxide ± calcite. The rocks are largely metaluminous with high SiO2, Na2O+ KO, Fe/Mg, Ga/Al, Zr, Ta, Sn, Y, REE and low CaO, Ba, Sr contents; the composition points to an ‘A-type granite’ melt. The rocks show negative Cs-, Sr-, Eu- and Ti- anomalies with incompatible element concentrations 2–3 times more than the upper continental crust (UCC). LREE is high (La/Yb ∼20) and HREE 20-30 times chondritic. 18 Owhole-rock varies between 4.4 and 7.8‰(mean 5.87 ± 1.26‰). The Bijli melt is neither formed by fractionation of a basaltic magma, nor does it represent a fractionated crustal melt. It is shown that the mantle-derived high temperature basaltic komatiitic melts/high Mg basalts triggered crustal melting, and interacted predominantly with deep crust compositionally similar to the Average Archaean Granulite (AAG), and a shallower crustal component with low CaO and Al2O3 to give rise to the hybrid Bijli melts. Geochemical mass balance suggests that ∼30% partial melting of AAG under anhydrous condition, instead of the upper continental crust (UCC) including the Amgaon granitoid gneiss reported from the area, better matches the trace element concentrations in the rocks. The similar Ta/Th of the rhyolites (0.060) and average granulite (0.065) vs. UCC (0.13) also support a deep crustal protolith. Variable contributions of crust and mantle, and action of hydrothermal fluid are attributed for the spread in 18Owhole-rock values. The fast eruption of high

  11. A titration approach to identify the capacity for starch digestion in milk-fed calves.

    Science.gov (United States)

    Gilbert, M S; van den Borne, J J G C; Berends, H; Pantophlet, A J; Schols, H A; Gerrits, W J J

    2015-02-01

    Calf milk replacers (MR) commonly contain 40% to 50% lactose. For economic reasons, starch is of interest as a lactose replacer. Compared with lactose, starch digestion is generally low in calves. It is, however, unknown which enzyme limits the rate of starch digestion. The objectives were to determine which enzyme limits starch digestion and to assess the maximum capacity for starch digestion in milk-fed calves. A within-animal titration study was performed, where lactose was exchanged stepwise for one of four starch products (SP). The four corn-based SP differed in size and branching, therefore requiring different ratios of starch-degrading enzymes for their complete hydrolysis to glucose: gelatinised starch (α-amylase and (iso)maltase); maltodextrin ((iso)maltase and α-amylase); maltodextrin with α-1,6-branching (isomaltase, maltase and α-amylase) and maltose (maltase). When exceeding the animal's capacity to enzymatically hydrolyse starch, fermentation occurs, leading to a reduced faecal dry matter (DM) content and pH. Forty calves (13 weeks of age) were assigned to either a lactose control diet or one of four titration strategies (n=8 per treatment), each testing the stepwise exchange of lactose for one SP. Dietary inclusion of each SP was increased weekly by 3% at the expense of lactose and faecal samples were collected from the rectum weekly to determine DM content and pH. The increase in SP inclusion was stopped when faecal DM content dropped below 10.6% (i.e. 75% of the average initial faecal DM content) for 3 consecutive weeks. For control calves, faecal DM content and pH did not change over time. For 87% of the SP-fed calves, faecal DM and pH decreased already at low inclusion levels, and linear regression provided a better fit of the data (faecal DM content or pH v. time) than non-linear regression. For all SP treatments, faecal DM content and pH decreased in time (Pstarch digestion and that fermentation may contribute substantially to total tract

  12. Who is who in the understory: the contribution of resident and transitory groups of species to plant richness in forest assemblages

    Directory of Open Access Journals (Sweden)

    JulianaSilva Gomes-Westphalen

    2012-09-01

    Full Text Available The forest understory is made up of resident and transitory species and can be much richer than the canopy. With the purpose to describe the contribution of these groups to the woody understory, five Atlantic Forest fragments were selected and studied in Northeastern Brazil. In order to analyze the understory’s structure, the sample included woody individuals with circumference at breast height (CBH smaller than 15cm and circumference at ground level (CGL greater than 3cm, regardless of height. The recorded species were quantified and classified into functional stratification categories (resident and transitory, and the floristic similarity between the understory and the tree stratum was calculated. Species’ importance in the understory was analyzed by height and total natural regeneration classes based on a regeneration index. The understory was richer in species (median=63.8, SD=21.72, n=5 fragments than the tree stratum (43.8, 18.14, 5, and the similarity between these components was relatively high (median=0.54, SD=0.09. The results also showed that the studied understory in the forest fragments was mainly composed by transitory species (median=67.01%, SD=3.76, that were well distributed among height classes and had the highest densities, which may favor their future presence in the canopy’s structure and composition. The typical understory species were grouped into two strata: the lower understory, made up of species that generally do not reach more than 4m in height (mostly species from families Piperaceae, Rubiaceae and Melastomataceae; and the upper understory, with intermediate heights between the lower understory and the canopy, but with average heights that were not higher than 10m (mainly of species from families Anonnaceae, Clusiaceae and Myrtaceae. These families’ richness was commonly used as an indicator of the vegetation’s successional stage; however, such results must be seen with caution as they show that these

  13. 混合离子的沉淀准确滴定%Precipitation Titration for Multiple Ions

    Institute of Scientific and Technical Information of China (English)

    乔成立

    2016-01-01

    The absolute value of titration break in precipitation titration is deduced with the Ringbom titration curve equation, and the conditions for accurate precipitation titration are thus deduced with the absolute value of the titration break.%用沉淀滴定的林邦滴定曲线方程推导滴定突跃的绝对值,用滴定突跃的绝对值推导混合离子准确滴定的条件。

  14. Determination of arsenic(III), sulphite and sulphur dioxide using the triangle programmed coulometric titration principle

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, F.; Buschmann, N. (Muenster Univ. (Germany, F.R.))

    1990-11-01

    In 1975, Pungor et al. established a new method called Triangle Programmed Coulometric Titration, which allows to titrate flowing sample solutions. The following paper presents a new analytical procedure for the determination of sulphur dioxide based on this technique. To obtain this, sulphur dioxide was transferred across a semipermeable membrane from a gaseous phase into an aqueous acceptor phase. Then the SO{sub 2}-concentration of the streaming aqueous phase was analysed bromometrically using the Triangle Programmed Coulometric Titration principle. The titration curves were followed continuously by an AC-bivoltammetric flow-through detector. Using this procedure a determination of SO{sub 2} concentrations between 400 and 2500 mg/m{sup 3} was possible.(orig.).

  15. Simple home-made sensors for potentiometric titrations. [Nitroform CH(NO/sub 2/)/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Selig, W.

    1982-04-01

    A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctyphthalate in tetrahydrofuran. The reference electrode was an Ag/AgCl single-junction electrode. The sensor was used in precipitation, acid-base, compleximetric, and redox titrations. Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane. Various uncoated types of graphite have also been investigated as sensors, particularly in two applications of interest in the analysis of propellants: the titration of nitroform and perchlorate. Obviously, these sensors can be used also in nonaqueous, or partially nonaqueous media. These sensors may also find use in the potentiometric titration of fluoride vs La(III) or Th(IV).

  16. Opuntia ficus indica (L.) Fruit Extract as Natural Indicator in Acid-Base Titration

    OpenAIRE

    Manoj A. Suva

    2014-01-01

    In routine experiments synthetic indicators are the choice of acid base titrations. But there are some limitations like environmental pollution, availability and higher cost which leads to search for natural compounds as an acid base indicator was started. The present work highlights theexploit of the methanolic and aqueous extract of the fruit of Opuntia ficus indica plants as a natural acid base indicator in acid base titrations. Opuntia ficus indica plant was identified and fruits were was...

  17. The Softening of Hard Water and Complexometric Titrations. An Undergraduate Experiment

    Science.gov (United States)

    Ceretti, Helena; Hughes, Enrique A.; Zalts, Anita

    1999-10-01

    A 2-hour experiment for undergraduates is presented in which (i) water hardness is explained and demonstrated; (ii) ion-exchange resin properties are visually demonstrated and then used for softening water; (iii) complexometric titrations are used for evaluating water hardness before and after softening; and (iv) acid-base titration can be used to show that the Ca/Mg ions removed by the ion exchanger are replaced by H ions.

  18. Comparison of the surface ion density of silica gel evaluated via spectral induced polarization versus acid-base titration

    Science.gov (United States)

    Hao, Na; Moysey, Stephen M. J.; Powell, Brian A.; Ntarlagiannis, Dimitrios

    2016-12-01

    Surface complexation models are widely used with batch adsorption experiments to characterize and predict surface geochemical processes in porous media. In contrast, the spectral induced polarization (SIP) method has recently been used to non-invasively monitor in situ subsurface chemical reactions in porous media, such as ion adsorption processes on mineral surfaces. Here we compare these tools for investigating surface site density changes during pH-dependent sodium adsorption on a silica gel. Continuous SIP measurements were conducted using a lab scale column packed with silica gel. A constant inflow of 0.05 M NaCl solution was introduced to the column while the influent pH was changed from 7.0 to 10.0 over the course of the experiment. The SIP measurements indicate that the pH change caused a 38.49 ± 0.30 μS cm- 1 increase in the imaginary conductivity of the silica gel. This increase is thought to result from deprotonation of silanol groups on the silica gel surface caused by the rise in pH, followed by sorption of Na+ cations. Fitting the SIP data using the mechanistic model of Leroy et al. (Leroyet al., 2008), which is based on the triple layer model of a mineral surface, we estimated an increase in the silica gel surface site density of 26.9 × 1016 sites m- 2. We independently used a potentiometric acid-base titration data for the silica gel to calibrate the triple layer model using the software FITEQL and observed a total increase in the surface site density for sodium sorption of 11.2 × 1016 sites m- 2, which is approximately 2.4 times smaller than the value estimated using the SIP model. By simulating the SIP response based on the calibrated surface complexation model, we found a moderate association between the measured and estimated imaginary conductivity (R2 = 0.65). These results suggest that the surface complexation model used here does not capture all mechanisms contributing to polarization of the silica gel captured by the SIP data.

  19. Characterization of the cell surface and cell wall chemistry of drinking water bacteria by combining XPS, FTIR spectroscopy, modeling, and potentiometric titrations.

    Science.gov (United States)

    Ojeda, Jesús J; Romero-Gonzalez, María E; Bachmann, Robert T; Edyvean, Robert G J; Banwart, Steven A

    2008-04-15

    Aquabacterium commune, a predominant member of European drinking water biofilms, was chosen as a model bacterium to study the role of functional groups on the cell surface that control the changes in the chemical cell surface properties in aqueous electrolyte solutions at different pH values. Cell surface properties of A. commune were examined by potentiometric titrations, modeling, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. By combining FTIR data at different pH values and potentiometric titration data with thermodynamic model optimization, the presence, concentration, and changes of organic functional groups on the cell surface (e.g., carboxyl, phosphoryl, and amine groups) were inferred. The pH of zero proton charge, pH(zpc) = 3.7, found from titrations of A. commune at different electrolyte concentrations and resulting from equilibrium speciation calculations suggests that the net surface charge is negative at drinking water pH in the absence of other charge determining ions. In situ FTIR was used to describe and monitor chemical interactions between bacteria and liquid solutions at different pH in real time. XPS analysis was performed to quantify the elemental surface composition, to assess the local chemical environment of carbon and oxygen at the cell wall, and to calculate the overall concentrations of polysaccharides, peptides, and hydrocarbon compounds of the cell surface. Thermodynamic parameters for proton adsorption are compared with parameters for other gram-negative bacteria. This work shows how the combination of potentiometric titrations, modeling, XPS, and FTIR spectroscopy allows a more comprehensive characterization of bacterial cell surfaces and cell wall reactivity as the initial step to understand the fundamental mechanisms involved in bacterial adhesion to solid surfaces and transport in aqueous systems.

  20. Solution titration by wall deprotonation during capillary filling of silicon oxide nanochannels.

    Science.gov (United States)

    Janssen, Kjeld G H; Hoang, T Hanh; Floris, Jan; de Vries, Jeroen; Tas, Niels R; Eijkel, Jan C T; Hankemeier, Thomas

    2008-11-01

    This paper describes a fundamental challenge when using silicon oxide nanochannels for analytical systems, namely the occurrence of a strong proton release or proton uptake from the walls in any transient situation such as channel filling. Experimentally, when fluorescein solutions were introduced into silicon oxide nanochannels through capillary pressure, a distinct bisection of the fluorescence was observed, the zone of the fluid near the entrance fluoresced, while the zone near the meniscus, was dark. The ratio between the zones was found to be constant in time and to depend on ionic strength, pH, and the presence of a buffer and its characteristics. Theoretically, using the Gouy-Chapman-Stern model of the electrochemical double layer, we demonstrate that this phenomenon can be effectively modeled as a titration of the solution by protons released from silanol groups on the walls, as a function of the pH and ionic strength of the introduced solution. The results demonstrate the dominant influence of the surface on the fluid composition in nanofluidic experiments, in transient situations such as filling, and changes in solvent properties such as the pH or ionic strength. The implications of these fundamental properties of silicon oxide nanochannels are important for analytical strategies and in particular the analysis of complex biological samples.

  1. Model compounds of humic acid and oxovanadium cations. Potentiometric titration and EPR spectroscopy studies

    Directory of Open Access Journals (Sweden)

    Mercê Ana Lucia Ramalho

    1999-01-01

    Full Text Available The stability constants and the isotropic EPR parameters Ao (hyperfine splitting constant and g o (g value were obtained by potentiometric titrations and EPR spectroscopy, respectively, of 85%v/v aqueous solutions of model compounds of humic acids - salicylic acid (SALA - and both nitrohumic acids, a laboratory artifact - nitrosalicylic acids, 3-nitrosalicylic acid (3-NSA, 5-nitrosalicylic acid (5-NSA and 3,5-dinitrosalicylic acid (3,5-DNSA and oxovanadium cations. It was possible to record EPR spectra of those model compounds and the ion VO2+ (V(IV, and the stability constants were obtained from a solution of VO3+ (V(V, the values for the logarithms of the stability constants ranging from 12.77 ± 0.04 to 7.06 ± 0.05 for the species ML, and from 9.90 ±0.04 to 4.06 ± 0.05 for the species ML2 according to the decrease in the acidity of the carboxylic and the hydroxyl groups in the aromatic ring of the model compounds studied as the -NO2 substituents were added. Species distribution diagrams were also obtained for the equilibria studied. The EPR parameters showed that as the logarithm of the overall stability constants increase, g o values also increase, while Ao values show a tendency to decrease.

  2. Water determination in iron oxyhydroxides and iron ores by Karl Fischer titration

    Science.gov (United States)

    da Cunha, Camila C. R. F.; da Costa, Geraldo M.

    2016-08-01

    Protohematite (Fe2-x/3(OH) x O3-x 1 ≤ x hydroxyl groups in their structures. These species were described in prior studies mainly with the aid of X-ray diffraction and Infrared spectroscopy. The existence of these phases in soils might have influence in redox processes, and they were considered as a possible water reservoir in Martian soils. In this study, we have used for the first time the Karl Fischer titration method to determine the amount of water released after heating several synthetic samples of goethite, hematite and natural iron ores at 105, 400, 600 and 900 °C. It was found that heating at 105 °C did not remove all moisture from the samples, and higher temperatures were necessary to completely remove all the absorbed water. The water contents determined at 400, 600 and 900 °C were found to be the same within the experimental errors, suggesting the inexistence of both protohematite and hydrohematite in the investigated samples. Therefore, the above-mentioned effects of these phases in soils might have to be reevaluated.

  3. A visual detection of protein content based on titration of moving reaction boundary electrophoresis.

    Science.gov (United States)

    Wang, Hou-Yu; Guo, Cheng-Ye; Guo, Chen-Gang; Fan, Liu-Yin; Zhang, Lei; Cao, Cheng-Xi

    2013-04-24

    A visual electrophoretic titration method was firstly developed from the concept of moving reaction boundary (MRB) for protein content analysis. In the developed method, when the voltage was applied, the hydroxide ions in the cathodic vessel moved towards the anode, and neutralized the carboxyl groups of protein immobilized via highly cross-linked polyacrylamide gel (PAG), generating a MRB between the alkali and the immobilized protein. The boundary moving velocity (V(MRB)) was as a function of protein content, and an acid-base indicator was used to denote the boundary displacement. As a proof of concept, standard model proteins and biological samples were chosen for the experiments to study the feasibility of the developed method. The experiments revealed that good linear calibration functions between V(MRB) and protein content (correlation coefficients R>0.98). The experiments further demonstrated the following merits of developed method: (1) weak influence of non-protein nitrogen additives (e.g., melamine) adulterated in protein samples, (2) good agreement with the classic Kjeldahl method (R=0.9945), (3) fast measuring speed in total protein analysis of large samples from the same source, and (4) low limit of detection (0.02-0.15 mg mL(-1) for protein content), good precision (R.S.D. of intra-day less than 1.7% and inter-day less than 2.7%), and high recoveries (105-107%).

  4. Interaction of phenazinium dyes with double-stranded poly(A): spectroscopy and isothermal titration calorimetry studies.

    Science.gov (United States)

    Khan, Asma Yasmeen; Saha, Baishakhi; Kumar, Gopinatha Suresh

    2014-10-15

    A comprehensive study on the binding of phenazinium dyes viz. janus green B, indoine blue, safranine O and phenosafranine with double stranded poly(A) using various spectroscopic and calorimetric techniques is presented. A higher binding of janus green B and indoine blue over safranine O and phenosafranine to poly(A) was observed from all experiments. Intercalative mode of binding of the dyes was inferred from fluorescence polarization anisotropy, iodide quenching and viscosity experiments. Circular dichroism study revealed significant perturbation of the secondary structure of poly(A) on binding of these dyes. Results from isothermal titration calorimetry experiments suggested that the binding was predominantly entropy driven with a minor contribution of enthalpy to the standard molar Gibbs energy. The results presented here may open new opportunities in the application of these dyes as RNA targeted therapeutic agents.

  5. Kinetics and thermodynamics of interaction between sulfonamide antibiotics and humic acids: Surface plasmon resonance and isothermal titration microcalorimetry analysis.

    Science.gov (United States)

    Xu, Juan; Yu, Han-Qing; Sheng, Guo-Ping

    2016-01-25

    The presence of sulfonamide antibiotics in the environments has been recognized as a crucial issue. Their migration and transformation in the environment is determined by natural organic matters that widely exist in natural water and soil. In this study, the kinetics and thermodynamics of interactions between humic acids (HA) and sulfamethazine (SMZ) were investigated by employing surface plasmon resonance (SPR) combined with isothermal titration microcalorimetry (ITC) technologies. Results show that SMZ could be effectively bound with HA. The binding strength could be enhanced by increasing ionic strength and decreasing temperature. High pH was not favorable for the interaction. Hydrogen bond and electrostatic interaction may play important roles in driving the binding process, with auxiliary contribution from hydrophobic interaction. The results implied that HA existed in the environment may have a significant influence on the migration and transformation of organic pollutants through the binding process.

  6. Astrophyllite-group minerals from the Ilímaussaq complex, South Greenland (contribution to the mineralogy of Ilímaussaq no. 123)

    DEFF Research Database (Denmark)

    Macdonald, R.; Karup-Møller, Sven; Rose-Hansen, J.

    2007-01-01

    in the formation of kupletskite in some rocks. Altered zones in certain astrophyllites and niobophyllites have compositional features similar to the type 'hydroastrophyllite'. The astrophyllite-group minerals in the hydrothermal veins crystallized at temperatures below 400°C at 1 kbar and under high pH and low......Electron microprobe analyses are presented for astrophyllite-group minerals from hydrothermal veins and pegmatites of the Ilimaussaq complex, South Greenland. The analyses fall mainly into two groups: (1) niobophyllites with the highest Nb/(Nb+Ti) ratios yet recorded (∼0.9), occurring only...

  7. A study on the uncertainty in the analytical results of uranium potentiometric titration method used by the Safeguards Laboratory of CNEN - Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Pedro Dionisio de; Araujo, Radier Mario S. de [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Coordenacao de Salvaguardas e Protecao Fisica. Lab. de Salvaguardas], E-mail: pedrodio@ird.gov.br, E-mail: radier@ird.gov.br; Dunley, Leonardo Souza [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao de Salvaguardas e Protecao Fisica], E-mail: leonardo@cnen.gov.br

    2007-07-01

    Independent determination of uranium content in nuclear materials to assess operator's declarations is an important tool in the safeguards approaches applied to nuclear installations. This determination may be performed by nondestructive methods, generally done in the field using portable radiation detection systems, or destructive methods by chemical analysis when more accurate results are necessary. In Brazil, samples are taken during safeguards inspections and sent to Safeguards Laboratory-LASAL of the Brazilian Nuclear Energy Commission-CNEN, where analysis is performed. The method used by LASAL for determination of uranium in several forms of nuclear material is the Davies and Gray/NBL using a potentiometric titrator, which performs the titration of uranium IV by a standard solution of K{sub 2}Cr{sub 2}O{sub 7}. Except the titration itself, which is performed by the addition of a certain volume of K{sub 2}Cr{sub 2}O{sub 7} solution, all the proceedings for sample and standard solutions preparation are conducted in weigh basis, including the aliquanting process. Firstly, all the parameters that can interfere with the uncertainty were studied. In order to evaluate their contribution in the final uncertainty, the uncertainties of all steps of the analysis method were estimated and compiled. Sensitivity coefficients were calculated as necessary for the appropriate propagation of uncertainties. Therefore, the standard and the expanded uncertainty were obtained. The confidence interval used was 95.45% with a coverage factor (k) of about 2. (author)

  8. Determination of acid dissociation constants of some hydroxy schiff bases by pH-metric titration. application of the Hammett equation

    Directory of Open Access Journals (Sweden)

    Hadjeb R.

    2013-07-01

    Full Text Available Ten compounds hydroxybases Schiff were synthesized from salicylaldehyde and the substituted aniline in the ortho, meta and para methyl groups, chloro and nitro. To study the effect of substituents on their acidities, the acid dissociation constants( Ka of salicylideneaniline and some of their derivatives were determined by pH-metric titration. All Schiff bases were titrated with NaOH in mixtures of 60% dioxane-water and 60% ethanol-water at a constant ionic strength and a temperature of 25 °C. The calculated acidity constants, pKa values were evaluated in protonation –deprotanation mechanisms. The Hammett relationship linear type was applied to quantify the effects of substituents on the acidity of hydroxybases Schiff, and therefore a reaction constant, ρ is calculated.

  9. Prediction of Enthalpy of Formation in the Solid State (at 298.15 K) using Second-Order Group Contributions. Part 1. Carbon-Hydrogen and Carbon-Hydrogen-Oxygen Compounds

    Science.gov (United States)

    Salmon, Anna; Dalmazzone, Didier

    2006-09-01

    A predictive method, based on Benson's group additivity technique, is developed for calculating the enthalpy of formation in the solid phase, at 298.15K, of carbon-hydrogen compounds and carbon-hydrogen-oxygen compounds. A complete database compiles 398 experimental enthalpies of formation. The whole group contribution values, ring strain corrections, and nonnearest neighbor interactions evaluated are listed. Finally a comparison with Cohen's method indicates that this new estimation method leads to higher precision and reliability.

  10. An investigation of CYP2D6 genotype and response to metoprolol CR/XL during dose titration in patients with heart failure: a MERIT-HF substudy.

    Science.gov (United States)

    Batty, J A; Hall, A S; White, H L; Wikstrand, J; de Boer, R A; van Veldhuisen, D J; van der Harst, P; Waagstein, F; Hjalmarson, Å; Kjekshus, J; Balmforth, A J

    2014-03-01

    To explore the pharmacogenetic effects of the cytochrome P450 (CYP)2D6 genotype in patients with systolic heart failure treated using controlled/extended-release (CR/XL) metoprolol, this study assessed the CYP2D6 locus for the nonfunctional *4 allele (1846G>A; rs3892097) in the Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure (MERIT-HF; n = 605). Participants were characterized as extensive, intermediate, or poor metabolizers (EMs, IMs, or PMs, respectively), based on the presence of the CYP2D6*4 allele (EM: *1*1, 60.4%; IM: *1*4, 35.8%; and PM: *4*4, 3.8%). Plasma metoprolol concentrations were 2.1-/4.6-fold greater in the IM/PM groups as compared with the EM group (P Metoprolol induced significantly lower heart rates and diastolic blood pressures during early titration, indicating a CYP2D6*4 allele dose-response effect (P metoprolol pharmacokinetics/pharmacodynamics during early titration; however, the MERIT-HF-defined titration schedule remains recommended for all patients, regardless of genotype.

  11. Titrated flow versus fixed flow Bubble Nasal CPAP for respiratory distress in preterm neonates.

    Directory of Open Access Journals (Sweden)

    Srinivas eMurki

    2015-10-01

    Full Text Available Background: The clinical effects of a pre-fixed flow of air-oxygen versus a flow titrated according to visible bubbling are not well understood.Objective: To compare the effects of a fixed flow (5 L/min and titrated flow ( flow just enough to ensure bubbling at different set pressures on delivered intra-prong pressure, gas exchange and clinical parameters in preterm infants on bubble CPAP for respiratory distress.Methods: Preterm infants less than 35 weeks gestation on bubble CPAP and less than 96 h of age, were enrolled in this cross over study. They were subjected to 30 minute periods of titrated flow and fixed flow. At the end of both epochs, gas flow rate, set pressure, FiO2, SpO2, Silverman retraction score, respiratory rate , abdominal girth, and blood gases were recorded. The delivered intra-prong pressure was measured by an electronic manometer. Results: Sixty nine recordings were made in 54 infants. For each of the set CPAP pressures (4, 5 and 6 cm H2O, the mean delivered pressure with a fixed flow of 5 L/min was higher than that delivered by the titrated flow. During the fixed flow epoch, the delivered pressure was closer to and higher than the set pressure resulting in higher PaO2 and lower PaCO2 as compared to titrated flow epoch. In the titrated flow period, the delivered pressure was consistently lower than the set pressure. Conclusion: In preterm infants on bubble CPAP with set pressures of 4 to 6 cm H2O, a fixed flow of 5 L/min is more effective than a flow titrated to ensure adequate visible bubbling. It achieves higher delivered pressures, better oxygenation and ventilation.

  12. Poly(ethylene glycol or Poly(ethylene oxide?: Magnitude of end-group Contribution to the Partitioning of Ethylene Oxide Oligomers and Polymers between Water and Organic Phases

    Directory of Open Access Journals (Sweden)

    Spitzer Marcos

    2002-01-01

    Full Text Available PEO partitioning from water to CH2Cl2 and CHCl3 increases with its molar mass, leveling off at ca. 3 000 g mol-1. Such a behaviour is related to PEO end-group contributions, suggesting a polyglycol to polyether transition at ca. 3 000 g mol-1.

  13. HOW THE DEPRECIATION METHOD CONTRIBUTES TO ESTIMATING FUTURE TREASURY FLOWS OUT OF THE ASSETS USE – CASE STUDY IN THE GROUPS OF SOCIETIES FROM THE ROMANIAN AREA

    Directory of Open Access Journals (Sweden)

    Manea Marinela - Daniela

    2015-05-01

    Full Text Available The current paper further pursues a previous research which sets out to test the contribution of the amortization method to generating the future cash flows from using tangible fixed assets within the European and Romania area. The process was initiated out of the necessity to identify new working tools available for the Romanian accountant professionals with regard to implementing the provisions of the accounting international standards (IFRS and it came across the difficulty of modeling the sample – 40 societies – and collecting information from financial situations, often incomplete, insufficiently formalized and difficult to process.

  14. Contribution to the conception, the modelling and the control of automotive power train and of electric converters; Contribution a la conception, la modelisation et la commande du groupe motopropulseur automobile et de convertisseurs d`energie electrique

    Energy Technology Data Exchange (ETDEWEB)

    Bidan, P.

    1998-12-14

    The overall work presented in this thesis globally deals with the conception, the modelling and the control of some applied systems. The first part is devoted to the automotive domain. It concerns the still actualized context of energy savings and reduction of atmospheric pollution, by the improvement of the engine/drive-train control and more particularly of the spark-ignition engine control. In this aim, a first investigation deals with the fuel/air ratio control during the transient phases and suggests the use of an intake manifold pressure control by means of an electric throttle actuator, in order to control the air filling. An original strategy of simultaneous control of fuel and air fillings is then proposed. Another improvement method by an electrical assistance of the engine using a self-controlled synchronous machine drive, is also developed. In the frame of idle-speed control, a prototype allows to show the contribution of this assistance in term of stability and consumption reduction. The second part of the report principally deals with the modelling and the control of electric converters. After a first section describing a methodology of a control-oriented modelling for some classes of static converters, an example of a design of the whole converter-controller is suggested. On the basis of a fourth order voltage switched-mode inverter which should operate as a function generator, the close interaction between filtering quality, structure design and control performances is analyzed and a solution is proposed. For every subject taken up, some prospective features are suggested as well. (author) 37 refs.

  15. Using Spectrophotometric Titrations To Characterize Humic Acid Reactivity at Environmental Concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Janot, N.; Benedetti, M. F. [Univ Paris Diderot, Lab Geochim Eaux, UMR CNRS 7154, IPGP, F-75025 Paris 13 (France); Janot, N.; Reiller, P. E. [CE Saclay, CEA DEN DANS DPC SECR, Lab Speciat Radionucleides and Mol, F-91191 Gif Sur Yvette (France); Korshin, G. V. [Univ Washington, Dept Civil and Environm Engn, Seattle, WA 98195 (United States)

    2010-07-01

    Potentiometric titration is a common method to characterize dissolved organic matter (DOM) reactivity. Because of the sensitivity of pH electrodes, it is necessary to work with very high DOM ({>=}1 g/L) concentrations that are unrealistic compared to those found in natural waters (0. 1 to 100 mg/L). To obtain proton binding data for concentrations closer to environmental values, spectroscopic titration methodology is a viable alternative to traditional potentiometric titrations. Spectrophotometric titrations and UV visible spectra of a diluted solution of purified Aldrich humic acid (5 mg(DOC)/L) are used to estimate changes in proton binding moieties as function of pH and ionic strength after calculation of differential absorbance spectra variations. After electrostatic correction of spectrophotometric data, there is a linear operational correlation between spectrophotometric and potentiometric data which can be used as a transfer function between the two properties. Spectrophotometric titrations are then used to determine the changes of humic acid protonation after adsorption onto alpha-alumina. (authors)

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

    Science.gov (United States)

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

    2010-09-01

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

  17. Use of isothermal titration calorimetry to study surfactant aggregation in colloidal systems.

    Science.gov (United States)

    Loh, Watson; Brinatti, César; Tam, Kam Chiu

    2016-05-01

    Isothermal titration calorimetry (ITC) is a general technique that allows for precise and highly sensitive measurements. These measurements may provide a complete and accurate thermodynamic description of association processes in complex systems such as colloidal mixtures. This review will address uses of ITC for studies of surfactant aggregation to form micelles, with emphasis on the thermodynamic studies of homologous surfactant series. We will also review studies on surfactant association with polymers of different molecular characteristics and with colloidal particles. ITC studies on the association of different homologous series of surfactants provide quantitative information on independent contribution from their apolar hydrocarbon chains and polar headgroups to the different thermodynamic functions associated with micellization (Gibbs energy, enthalpy and entropy). Studies on surfactant association to polymers by ITC provide a comprehensive description of the association process, including examples in which particular features revealed by ITC were elucidated by using ancillary techniques such as light or X-ray scattering measurements. Examples of uses of ITC to follow surfactant association to biomolecules such as proteins or DNA, or nanoparticles are also highlighted. Finally, recent theoretical models that were proposed to analyze ITC data in terms of binding/association processes are discussed. This review stresses the importance of using direct calorimetric measurements to obtain and report accurate thermodynamic data, even in complex systems. These data, whenever possible, should be confirmed and associated with other ancillary techniques that allow elucidation of the nature of the transformations detected by calorimetric results, providing a complete description of the process under scrutiny. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Social, Personal and Educational Constraints on Access to Employment among Groups at Risk of Social Exclusion: Contributions from an Employment Observatory

    Science.gov (United States)

    Anuncibay, Raquel de la Fuente

    2007-01-01

    One of the challenges raised by proactive employment policies centres on redressing inequalities that are not solely of an economic nature, as others may also be added of a social and ethnic nature as well as personal, cultural and educational aspects. This article analyses the situation in which groups at risk of social exclusion find themselves…

  19. Contribution of chronic diseases to disability in elderly people in countries with low and middle incomes: a 10/66 Dementia Research Group population-based survey

    Science.gov (United States)

    Sousa, Renata M; Ferri, Cleusa P; Acosta, Daisy; Albanese, Emiliano; Guerra, Mariella; Huang, Yueqin; Jacob, KS; Jotheeswaran, AT; Rodriguez, Juan J Llibre; Pichardo, Guillermina Rodriguez; Rodriguez, Marina Calvo; Salas, Aquiles; Sosa, Ana Luisa; Williams, Joseph; Zuniga, Tirso; Prince, Martin

    2009-01-01

    Summary Background Disability in elderly people in countries with low and middle incomes is little studied; according to Global Burden of Disease estimates, visual impairment is the leading contributor to years lived with disability in this population. We aimed to assess the contribution of physical, mental, and cognitive chronic diseases to disability, and the extent to which sociodemographic and health characteristics account for geographical variation in disability. Methods We undertook cross-sectional surveys of residents aged older than 65 years (n=15 022) in 11 sites in seven countries with low and middle incomes (China, India, Cuba, Dominican Republic, Venezuela, Mexico, and Peru). Disability was assessed with the 12-item WHO disability assessment schedule 2.0. Dementia, depression, hypertension, and chronic obstructive pulmonary disease were ascertained by clinical assessment; diabetes, stroke, and heart disease by self-reported diagnosis; and sensory, gastrointestinal, skin, limb, and arthritic disorders by self-reported impairment. Independent contributions to disability scores were assessed by zero-inflated negative binomial regression and Poisson regression to generate population-attributable prevalence fractions (PAPF). Findings In regions other than rural India and Venezuela, dementia made the largest contribution to disability (median PAPF 25·1% [IQR 19·2–43·6]). Other substantial contributors were stroke (11·4% [1·8–21·4]), limb impairment (10·5% [5·7–33·8]), arthritis (9·9% [3·2–34·8]), depression (8·3% [0·5–23·0]), eyesight problems (6·8% [1·7–17·6]), and gastrointestinal impairments (6·5% [0·3–23·1]). Associations with chronic diseases accounted for around two-thirds of prevalent disability. When zero inflation was taken into account, between-site differences in disability scores were largely attributable to compositional differences in health and sociodemographic characteristics. Interpretation On the basis

  20. 定位分布贡献方法估算有机物正常沸点%Position group contribution method for predicting the normal boiling point of organic compounds

    Institute of Scientific and Technical Information of China (English)

    王强; 马沛生; 王昶; 夏淑倩

    2009-01-01

    A new position group contribution model iS proposed for the estimation of normal boiling data of organic compounds involving a carbon chain from C2 to C18. The characteristic of this method iS the use of position distribution function.It could distinguish most of isomers that include cis-or trans-structure from organic compounds.Contributions for hydrocarbons and hydrocarbon derivatives containing oxygen,nitrogen,chlorine,bromine and sulfur,are given.Compared with the predictions,results made use of the most common existing group contribution methods,the overall average absolute difference of boiling point predictions of 417 organic compounds is 4.2 K:and the average absolute percent derivation is 1.0%,which iS compared with 1 2-3 K and 3.2%with the method of Joback.12.1 K and 3.1%with the method of Constantinou-Gani.This new position contribution groups mcthod is not only much more accurate but also has the advantages of simplicity and stability.

  1. Summary of Contributions to GAW Group 15: Family-Based Samples Are Useful in Identifying Common Polymorphisms Associated with Complex Traits

    OpenAIRE

    Knight, Stacey; Uh, Hae-Won; Martinez, Maria

    2009-01-01

    Traditionally, family-based samples have been used for genetic analyses of single-gene traits caused by rare but highly penetrant risk variants. The utility of family-based genetic data for analyzing common complex traits is unclear and contains numerous challenges. To assess the utility as well as to address these challenges, members of Genetic Analysis Workshop 16 Group 15 analyzed Framingham Heart Study data using family-based designs ranging from parent–offspring trios to large pedigrees....

  2. Contribution of the working group 2 to the fourth evaluation report of the inter government expert group on the climatic change. Evaluation 2007 of the climatic changes: impacts, adaptation and vulnerability; Contribution du Groupe de travail 2 au quatrieme rapport d'evaluation du Groupe d'expert intergouvernemental sur l'evolution du climat. Bilan 2007 des changements climatiques: impacts, adaptation et vulnerabilite

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    This document exposes the results of the fourth evaluation report of the working group II of the inter government experts group on the climatic change. This evaluation presents the today scientific understanding of the climatic change impacts on the humans and their adaptation ability and vulnerability. It is based on the GIEC evaluations and new knowledge added since the third evaluation report. (A.L.B.)

  3. Playing Games with Games People Play. Contributions of Gestalt Theory to Individual Counseling. Self-Discovery through Art: A Group Experience. A Review of Personal Research on Experimental-Gestalt Growth Groups. Gestalt Dreamwork as a Method for Self Discovery.

    Science.gov (United States)

    Guinan, James F.; And Others

    The existential Gestalt approach to facilitating the human growth process is discussed, from somewhat different vantage points, in these papers. Two seek to elaborate the basic principles and facilitating "techniques" of Gestalt therapy, while maintaining that one can truly understand only by experiencing. The use of Focus Groups, in which a focal…

  4. The role of DNA binding sites and slow unbinding kinetics in titration-based oscillators

    CERN Document Server

    Karapetyan, Sargis

    2015-01-01

    Genetic oscillators, such as circadian clocks, are constantly perturbed by molecular noise arising from the small number of molecules involved in gene regulation. One of the strongest sources of stochasticity is the binary noise that arises from the binding of a regulatory protein to a promoter in the chromosomal DNA. In this study, we focus on two minimal oscillators based on activator titration and repressor titration to understand the key parameters that are important for oscillations and for overcoming binary noise. We show that the rate of unbinding from the DNA, despite traditionally being considered a fast parameter, needs to be slow to broaden the space of oscillatory solutions. The addition of multiple, independent DNA binding sites further expands the oscillatory parameter space for the repressor-titration oscillator and lengthens the period of both oscillators. This effect is a combination of increased effective delay of the unbinding kinetics due to multiple binding sites and increased promoter ul...

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

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    FT-IR, Raman microscopy, XRD, 29 Si and 27 Al MAS NMR, were used to investigate changes in surface properties of a natural illitesample 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 withacid, then increased after hydroxide back titration. The varied ratio of signal intensity between Ⅳ Al and Ⅵ At species in 27 Al MAS NMRspectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure ofillite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illitesurfaces and acid-leaching silicic acid and aluminum ions should be considered in the model description of surface acid-base properties of theaqueous illite.

  6. Microbiological titration of proteins and of single amino acid content in biological materials without purification and hydrolysis.

    Science.gov (United States)

    Puppo, S; Morpurgo, G; Nardi, S; Conti, G

    1978-04-01

    A method is described for the microbiological determination of the protein content of biological materials. This method can also be adopted to titrate the concentration of a single amino acid in the protein and has the following advantages: (1) titration can be done without purification and hydrolysis of proteins; (2) the titration graph is a straight line between 25 and 800 microgram/ml; (3) protein values agree with those obtained using the Kjeldhal method; and (4) each mutant requiring one amino acid may be used to titrate the concentration of a single amino acid of the protein. The leucine content of various kinds of flour was measured with this system.

  7. A conserved virulence plasmidic region contributes to the virulence of the multiresistant Escherichia coli meningitis strain S286 belonging to phylogenetic group C.

    Directory of Open Access Journals (Sweden)

    Chloé Lemaître

    Full Text Available Recent isolation of the non-K1 Escherichia coli neonatal meningitis strain S286, belonging to phylogroup C, which is closely related to major group B1, and producing an extended-spectrum beta-lactamase, encouraged us to seek the genetic determinants responsible for its virulence. We show that S286 belongs to the sequence O type ST23O78 and harbors 4 large plasmids. The largest one, pS286colV (~120 kb, not related to resistance, contains genes characteristic of a Conserved Virulence Plasmidic (CVP region initially identified in B2 extra-intestinal avian pathogenic E. coli (APEC strains and in the B2 neonatal meningitis E. coli strain S88. The sequence of this CVP region has a strong homology (98% with that of the recently sequenced plasmid pChi7122-1 of the O78 APEC strain Chi7122. A CVP plasmid-cured variant of S286 was less virulent than the wild type strain in a neonatal rat sepsis model with a significant lower level of bacteremia at 24 h (4.1 ± 1.41 versus 2.60 ± 0.16 log CFU/ml, p = 0.001 and mortality. However, the mortality in the model of adult mice was comparable between wild type and variant indicating that pS286colV is not sufficient by itself to fully explain the virulence of S286. Gene expression analysis of pS286colV in iron depleted environment was very close to that of pS88, suggesting that genes of CVP region may be expressed similarly in two very different genetic backgrounds (group C versus group B2. Screening a collection of 178 human A/B1 extraintestinal pathogenic E. coli (ExPEC strains revealed that the CVP region is highly prevalent (23% and MLST analysis indicated that these CVP positive strains belong to several clusters and mostly to phylogroup C. The virulence of S286 is explained in part by the presence of CVP region and this region has spread in different clusters of human A/B1 ExPEC, especially in group C.

  8. A conserved virulence plasmidic region contributes to the virulence of the multiresistant Escherichia coli meningitis strain S286 belonging to phylogenetic group C.

    Science.gov (United States)

    Lemaître, Chloé; Mahjoub-Messai, Farah; Dupont, Damien; Caro, Valérie; Diancourt, Laure; Bingen, Edouard; Bidet, Philippe; Bonacorsi, Stéphane

    2013-01-01

    Recent isolation of the non-K1 Escherichia coli neonatal meningitis strain S286, belonging to phylogroup C, which is closely related to major group B1, and producing an extended-spectrum beta-lactamase, encouraged us to seek the genetic determinants responsible for its virulence. We show that S286 belongs to the sequence O type ST23O78 and harbors 4 large plasmids. The largest one, pS286colV (~120 kb), not related to resistance, contains genes characteristic of a Conserved Virulence Plasmidic (CVP) region initially identified in B2 extra-intestinal avian pathogenic E. coli (APEC) strains and in the B2 neonatal meningitis E. coli strain S88. The sequence of this CVP region has a strong homology (98%) with that of the recently sequenced plasmid pChi7122-1 of the O78 APEC strain Chi7122. A CVP plasmid-cured variant of S286 was less virulent than the wild type strain in a neonatal rat sepsis model with a significant lower level of bacteremia at 24 h (4.1 ± 1.41 versus 2.60 ± 0.16 log CFU/ml, p = 0.001) and mortality. However, the mortality in the model of adult mice was comparable between wild type and variant indicating that pS286colV is not sufficient by itself to fully explain the virulence of S286. Gene expression analysis of pS286colV in iron depleted environment was very close to that of pS88, suggesting that genes of CVP region may be expressed similarly in two very different genetic backgrounds (group C versus group B2). Screening a collection of 178 human A/B1 extraintestinal pathogenic E. coli (ExPEC) strains revealed that the CVP region is highly prevalent (23%) and MLST analysis indicated that these CVP positive strains belong to several clusters and mostly to phylogroup C. The virulence of S286 is explained in part by the presence of CVP region and this region has spread in different clusters of human A/B1 ExPEC, especially in group C.

  9. A Study to Identify Variables Contributing to Length of Stay for Selected Diagnosis Related Groups (DRG) at Madigan Army Medical Center

    Science.gov (United States)

    1989-06-07

    Margolis, and Wise 1986). A total of 215 patients 0 0in DRG 162 ( inguinal and femoral hernia repair, age 18 to 69 years C• C0 m without complications...the 0.05 level for one of the four DRGs. 0• " C 0m Additional analysis revealed that the diagnostic group, type of anesthesia , use of consultations...Allergy/Immunology I 1 Anesthesia I 1 Child Psychology 1 1 Dermatology I Developmental Peds I Emergency Medicine I Endocrinology 1 1 o Facul Devel

  10. No. 3063. Proposal of law aiming at establishing an exceptional tax on the excessive profits of petroleum groups; N. 3063. Proposition de loi visant a instituer une contribution exceptionnelle sur les surprofits des groupes petroliers

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzenberg, R.G

    2006-05-15

    The profits made by the six main oil companies (ExxonMobil, Shell, BP, Chevron, Philips and Total) reached 121 billion US$ in 2005, i.e. two times the gross domestic product of a country like Bulgaria. The beneficiaries of these profits are mainly the shareholders while a small part only is reinvested by oil companies in production capacities (the lack of refining capacities would be responsible for a third of the rise of petroleum products price). Considering the recent increase of automotive and space heating fuels price, this situation appears as neither legitimate, nor conformable with the general interest. The aim of this proposal of law is the establishment of a tax on excessive profits of oil companies. This tax would contribute to reduce the petroleum dependence of France and to prepare the French economy and society to the 'after-petroleum' era (development of collective transport systems, financing of research on alternate energy sources). (J.S.)

  11. Members of the RAD52 Epistasis Group Contribute to Mitochondrial Homologous Recombination and Double-Strand Break Repair in Saccharomyces cerevisiae.

    Science.gov (United States)

    Stein, Alexis; Kalifa, Lidza; Sia, Elaine A

    2015-11-01

    Mitochondria contain an independently maintained genome that encodes several proteins required for cellular respiration. Deletions in the mitochondrial genome have been identified that cause several maternally inherited diseases and are associated with certain cancers and neurological disorders. The majority of these deletions in human cells are flanked by short, repetitive sequences, suggesting that these deletions may result from recombination events. Our current understanding of the maintenance and repair of mtDNA is quite limited compared to our understanding of similar events in the nucleus. Many nuclear DNA repair proteins are now known to also localize to mitochondria, but their function and the mechanism of their action remain largely unknown. This study investigated the contribution of the nuclear double-strand break repair (DSBR) proteins Rad51p, Rad52p and Rad59p in mtDNA repair. We have determined that both Rad51p and Rad59p are localized to the matrix of the mitochondria and that Rad51p binds directly to mitochondrial DNA. In addition, a mitochondrially-targeted restriction endonuclease (mtLS-KpnI) was used to produce a unique double-strand break (DSB) in the mitochondrial genome, which allowed direct analysis of DSB repair in vivo in Saccharomyces cerevisiae. We find that loss of these three proteins significantly decreases the rate of spontaneous deletion events and the loss of Rad51p and Rad59p impairs the repair of induced mtDNA DSBs.

  12. Failure in distinguishing colored noise from chaos using the ``noise titration'' technique

    Science.gov (United States)

    Freitas, Ubiratan S.; Letellier, Christophe; Aguirre, Luis A.

    2009-03-01

    Identifying chaos in experimental data—noisy data—remains a challenging problem for which conclusive arguments are still very difficult to provide. In order to avoid problems usually encountered with techniques based on geometrical invariants (dimensions, Lyapunov exponent, etc.), Poon and Barahona introduced a numerical titration procedure which compares one-step-ahead predictions of linear and nonlinear models [Proc. Natl. Acad. Sci. U.S.A. 98, 7107 (2001)]. We investigate the aformentioned technique in the context of colored noise or other types of nonchaotic behaviors. The main conclusion is that in several examples noise titration fails to distinguish such nonchaotic signals from low-dimensional deterministic chaos.

  13. Monitoring of an RNA Multistep Folding Pathway by Isothermal Titration Calorimetry

    Science.gov (United States)

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

    2009-01-01

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

  14. Using Isothermal Titration Calorimetry to Determine Thermodynamic Parameters of Protein–Glycosaminoglycan Interactions

    Science.gov (United States)

    Dutta, Amit K.; Rösgen, Jörg; Rajarathnam, Krishna

    2015-01-01

    It has now become increasingly clear that a complete atomic description of how biomacromolecules recognize each other requires knowledge not only of the structures of the complexes but also of how kinetics and thermodynamics drive the binding process. In particular, such knowledge is lacking for protein–glycosaminoglycan (GAG) complexes. Isothermal titration calorimetry (ITC) is the only technique that can provide various thermodynamic parameters—enthalpy, entropy, free energy (binding constant), and stoichiometry—from a single experiment. Here we describe different factors that must be taken into consideration in carrying out ITC titrations to obtain meaningful thermodynamic data of protein–GAG interactions. PMID:25325962

  15. Complexometric titration with potenciometric indicator to determination of calcium and magnesium in soil extracts¹

    Directory of Open Access Journals (Sweden)

    Claudia Mara Pereira

    2011-08-01

    Full Text Available This study proposes a method of direct and simultaneous determination of the amount of Ca2+ and Mg2+ present in soil extracts using a Calcium Ion-Selective Electrode and by Complexometric Titration (ISE-CT. The results were compared to those obtained by conventional analytical techniques of Complexometric Titration (CT and Flame Atomic Absorption Spectrometry (FAAS. There were no significant differences in the determination of Ca2+ and Mg2+ in comparison with CT and FAAS, at a 95 % confidence level. Additionally, results of this method were more precise and accurate than of the Interlaboratorial Control (IC.

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

    OpenAIRE

    1996-01-01

    A computer program was developed that could advice on the choice of solvent and titrant for acid/base titrations in nonaqueous media. It is shown that the feasibility of a titration in a given solvent can be calculated from solvent properties and intrinsic acid/base properties of the sample components. A consistent set of properties for various solvents and a large number of acidic and basic compounds was calculated from literature data with the use of a genetic algorithm. Test results show t...

  17. Using isothermal titration calorimetry to determine thermodynamic parameters of protein-glycosaminoglycan interactions.

    Science.gov (United States)

    Dutta, Amit K; Rösgen, Jörg; Rajarathnam, Krishna

    2015-01-01

    It has now become increasingly clear that a complete atomic description of how biomacromolecules recognize each other requires knowledge not only of the structures of the complexes but also of how kinetics and thermodynamics drive the binding process. In particular, such knowledge is lacking for protein-glycosaminoglycan (GAG) complexes. Isothermal titration calorimetry (ITC) is the only technique that can provide various thermodynamic parameters-enthalpy, entropy, free energy (binding constant), and stoichiometry-from a single experiment. Here we describe different factors that must be taken into consideration in carrying out ITC titrations to obtain meaningful thermodynamic data of protein-GAG interactions.

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

    Science.gov (United States)

    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.

  19. Good clinical practice guide for opioids in pain management: the three Ts - titration (trial, tweaking (tailoring, transition (tapering

    Directory of Open Access Journals (Sweden)

    Flaminia Coluzzi

    2016-06-01

    Full Text Available ABSTRACT BACKGROUND AND OBJECTIVES: Achieving good clinical practice in the use of opioids as part of a comprehensive pain management regimen can face significant challenges. Despite guidelines from governmental and pain society/organization sources, there are still significant hurdles. A review of some basic tenets of opioid analgesia based on current published knowledge and experiences about this important healthcare imperative is warranted. CONTENT: Consistent with guidelines, the literature supports using the lowest total opioid dose that provides adequate pain control with the fewest adverse effects. Titration (or trial during opioid initiation is a way of starting low and going slow (and assessing the appropriateness of a specific opioid and formulation. Recognizing that multiple factors contribute to an individual's personal experience of pain, the physical, psychological, social, cultural, spiritual, pharmacogenomic, and behavioral factors of the individual patient should be taken into account (tweaking, or tailoring. Finally, for those patients for whom transition (tapering from opioid is desired, doing so too rapidly can have negative consequences and minimization of problems during this step can be achieved by proper tapering. CONCLUSION: We conclude that a simultaneously aggressive, yet conservative, approach is advocated in the literature in which opioid therapy is divided into three key steps (the 3 T's: titration (or trial, tweaking (or tailoring, and transition (or tapering. Establishment of the 3 T's along with the application of other appropriate good medical practice and clinical experience/judgment, including non-pharmacologic approaches, can assist healthcare providers in the effort to achieve optimal management of pain.

  20. Thermodynamics of calmodulin trapping by Ca2+/calmodulin-dependent protein kinase II: subpicomolar Kd determined using competition titration calorimetry.

    Science.gov (United States)

    Tse, Joyce K Y; Giannetti, Anthony M; Bradshaw, J Michael

    2007-04-03

    Calmodulin (CaM) trapping by Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a phenomenon whereby the affinity of CaM for CaMKII increases >1000-fold following CaMKII autophosphorylation. The molecular basis of this effect is not entirely understood. Binding of CaM to the phosphorylated and the unphosphorylated states of CaMKII is well mimicked by the interaction of CaM with two different length peptides taken from the CaM-binding region of CaMKII, peptides we refer to as the long and intermediate peptides. To better understand the conformational change accompanying CaM trapping, we have used isothermal titration calorimetry (ITC) to compare the binding thermodynamics of CaM to these peptides as well as to a shorter CaMKII-based peptide. Calorimetric analysis revealed that the enthalpy, rather than the entropy, distinguished binding of these three peptides. Furthermore, the heat capacity change was found to be similar for the long and intermediate peptides but smaller in magnitude for the short peptide. Direct titration of CaM with peptide provided the Kd value for the short peptide (Kd = 5.9 +/- 2.4 microM), but a novel, two-phased competitive binding strategy was necessary to ascertain the affinities of the intermediate (Kd = 0.17 +/- 0.06 nM) and long (Kd = 0.07 +/- 0.04 pM) peptides. To our knowledge, the Kd for the long peptide is the most potent measured to date using ITC. Together, the findings reported here support a model whereby the final conformational change accompanying CaM trapping buries little additional surface area but does involve formation of new hydrogen bonds and van der Waals contacts that contribute to formation of the high-affinity, CaM-trapped state.

  1. The UNESCO-IHP Working Group on Land Subsidence: Four Decades of International Contributions to Hydrogeological Related Subsidence Research and Knowledge Exchange

    Science.gov (United States)

    Galloway, D. L.; Carreon-Freyre, D.; Teatini, P.; Ye, S.

    2015-12-01

    Subsidence is globally prevalent and because much of it is related to hydrological processes affected by human development of local land and water resources, "Land Subsidence" was included in the UNESCO programme of the International Hydrological Decade (IHD), 1965-1974 and an ad hoc working group on land subsidence was formed. In 1975 subsidence was retained under the framework of the UNESCO IHP (subproject 8.4: "Investigation of Land Subsidence due to Groundwater Exploitation"), and UNESCO IHP formerly codified the Working Group on Land Subsidence (WGLS). In 1984 the WGLS produced a comprehensive guidebook to serve scientists and engineers, confronting land subsidence problems, particularly in developing countries (http://unesdoc.unesco.org/$other/unesdoc/pdf/065167eo.pdf). During the IHD, UNESCO IHP convened the 1st International Symposium on Land Subsidence in 1969 in Tokyo, Japan. In collaboration with UNESCO IHP, IAHS, and other scientific organizations, the WGLS has convened eight more International Symposia on Land Subsidence in different countries in Asia, Europe and North America. The 9 published symposia proceedings constitute an important source of global subsidence research and case studies during the past 45 years, covering both anthropogenic and natural subsidence processes. Currently, the WGLS comprising 20 subsidence experts from 9 countries promotes and facilitates the international exchange of information regarding the design, implementation and evaluation of risk assessments and mitigation measures, the definition of water and land resource-management strategies that support sustainable development in areas vulnerable to subsidence (http://landsubsidence-unesco.org), and the assessment of related geological risks such as earth fissuring and fault activation (www.igcp641.org). The WGLS has become an important global leader in promoting subsidence awareness, scientific research and its application to subsidence monitoring, analysis and management.

  2. Relative contribution of effects included in contemporary groups for adjusted and actual 120-day and 210-day weights in Nelore cattle in Brazil

    Directory of Open Access Journals (Sweden)

    Lillian Pascoa

    2011-01-01

    Full Text Available The objective of this research was to estimate the relative magnitude of effects included in contemporary groups (CG and their interactions with adjusted and actual 120 d and 210 d weights in 72, 731 male and female Nelore calves born from 1985 to 2005 in 40 herds from PMGRN (Genetic Improvement Program of Nelore. Ten models with different CG structures were compared. The analyses were done using the general linear models (GLM procedure run in SAS software. All of the effects included in the CG for each model were significant (p < 0.001 for the four traits analyzed. Inclusion of semester or trimester of birth as part of a CG was more appropriate than its use as an independent effect in the model because it accounted for interactions with the other effects in the CG. Calf sex (CS and dam age at calving (DAC had similar effects across the models, which suggested independence from other effects in these models. The corresponding age deviation effect had a larger impact on actual weight at 120 d than any other effect in all of the models tested. The use of actual weights in models with no CS effect in CG provides an alternative that would allow better genetic connectedness among CGs and greater accuracy in genetic evaluations.

  3. Isothermal Titration Calorimetry Measurements of Metal Ions Binding to Proteins.

    Science.gov (United States)

    Quinn, Colette F; Carpenter, Margaret C; Croteau, Molly L; Wilcox, Dean E

    2016-01-01

    ITC measurements involving metal ions are susceptible to a number of competing reactions (oxidation, precipitation, and hydrolysis) and coupled reactions involving the buffer and protons. Stabilization and delivery of the metal ion as a well-defined and well-characterized complex with the buffer, or a specific ligand, can suppress undesired solution chemistry and, depending on the stability of the metal complex, allow accurate measurements of higher affinity protein-binding sites. This requires, however, knowledge of the thermodynamics of formation of the metal complex and accounting for its contribution to the experimentally measured values (KITC and ΔHITC) through a post hoc analysis that provides the condition-independent binding thermodynamics (K, ΔG(o), ΔH, ΔS, and ΔCP). This analysis also quantifies the number of protons that are displaced when the metal ion binds to the protein. © 2016 Elsevier Inc. All rights reserved.

  4. Determining DNA supercoiling enthalpy by isothermal titration calorimetry.

    Science.gov (United States)

    Xu, Xiaozhou; Zhi, Xiaoduo; Leng, Fenfei

    2012-12-01

    DNA supercoiling plays a critical role in certain essential DNA transactions, such as DNA replication, recombination, and transcription. For this reason, exploring energetics of DNA supercoiling is fundamentally important for understanding its biological functions. In this paper, using a unique property of DNA intercalators, such as ethidium bromide and daunorubicin, which bind to supercoiled, nicked, and relaxed DNA templates with different DNA-binding enthalpies, we determined DNA supercoiling enthalpy of plasmid pXXZ6, a 4.5 kb plasmid to be about 11.5 kcal/mol per linking number change. This determination allowed us to partition the DNA supercoiling free energy into enthalpic and entropic contributions where the unfavorable DNA supercoiling free energy exclusively originated from the large positive supercoiling enthalpy and was compensated by a large, favorable entropy term (TΔS). Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  5. Building a Privacy, Ethics, and Data Access Framework for Real World Computerised Medical Record System Data: A Delphi Study. Contribution of the Primary Health Care Informatics Working Group.

    Science.gov (United States)

    Liyanage, H; Liaw, S-T; Di Iorio, C T; Kuziemsky, C; Schreiber, R; Terry, A L; de Lusignan, S

    2016-11-10

    Privacy, ethics, and data access issues pose significant challenges to the timely delivery of health research. Whilst the fundamental drivers to ensure that data access is ethical and satisfies privacy requirements are similar, they are often dealt with in varying ways by different approval processes. To achieve a consensus across an international panel of health care and informatics professionals on an integrated set of privacy and ethics principles that could accelerate health data access in data-driven health research projects. A three-round consensus development process was used. In round one, we developed a baseline framework for privacy, ethics, and data access based on a review of existing literature in the health, informatics, and policy domains. This was further developed using a two-round Delphi consensus building process involving 20 experts who were members of the International Medical Informatics Association (IMIA) and European Federation of Medical Informatics (EFMI) Primary Health Care Informatics Working Groups. To achieve consensus we required an extended Delphi process. The first round involved feedback on and development of the baseline framework. This consisted of four components: (1) ethical principles, (2) ethical guidance questions, (3) privacy and data access principles, and (4) privacy and data access guidance questions. Round two developed consensus in key areas of the revised framework, allowing the building of a newly, more detailed and descriptive framework. In the final round panel experts expressed their opinions, either as agreements or disagreements, on the ethics and privacy statements of the framework finding some of the previous round disagreements to be surprising in view of established ethical principles. This study develops a framework for an integrated approach to ethics and privacy. Privacy breech risk should not be considered in isolation but instead balanced by potential ethical benefit.

  6. A modelling approach to establish experimental parameters of a flow-through titration

    NARCIS (Netherlands)

    Reijnders, H.F.R.; Staden, J.J. van; Eelderink, G.H.B; Griepink, B.

    1980-01-01

    A flow-through titrimeter with optical detection and the flow-through titration of sulphate have been studied by using control engineering methods. Qualitative chemical descriptions and systems analysis yield a model covering different precipitation rates of barium sulphate. The validity of the mode

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

    Science.gov (United States)

    Krainer, Georg; Keller, Sandro

    2015-04-01

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

  8. Effect of Spacers on CMCs and Micelle-forming Enthalpies of Gemini Surfactants by Titration Microcalorimetry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The critical micelle concentrations (CMC) and the micelle-forming enthalpies (D Hmic) of gemini surfactants were first measured by the precise titration microcalorimetry. The results showed that D Hmic values are negative, and there is an exothermal minimum between s=4 and s=6. Furthermore, the CMCs of the surfactants are in good agreement with literature values.

  9. Isothermal Titration Calorimetry and Macromolecular Visualization for the Interaction of Lysozyme and Its Inhibitors

    Science.gov (United States)

    Wei, Chin-Chuan; Jensen, Drake; Boyle, Tiffany; O'Brien, Leah C.; De Meo, Cristina; Shabestary, Nahid; Eder, Douglas J.

    2015-01-01

    To provide a research-like experience to upper-division undergraduate students in a biochemistry teaching laboratory, isothermal titration calorimetry (ITC) is employed to determine the binding constants of lysozyme and its inhibitors, N-acetyl glucosamine trimer (NAG[subscript 3]) and monomer (NAG). The extremely weak binding of lysozyme/NAG is…

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    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…

  12. Thermodynamic profiling of Peptide membrane interactions by isothermal titration calorimetry: a search for pores and micelles

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Andresen, Thomas Lars

    2011-01-01

    in mixed peptide-lipid micelles. We have investigated the mode of action of the antimicrobial peptide mastoparan-X using isothermal titration calorimetry (ITC) and cryo-transmission electron microscopy (cryo-TEM). The results show that mastoparan-X induces a range of structural transitions of POPC/POPG (3...

  13. Isothermal Titration Calorimetry and Macromolecular Visualization for the Interaction of Lysozyme and Its Inhibitors

    Science.gov (United States)

    Wei, Chin-Chuan; Jensen, Drake; Boyle, Tiffany; O'Brien, Leah C.; De Meo, Cristina; Shabestary, Nahid; Eder, Douglas J.

    2015-01-01

    To provide a research-like experience to upper-division undergraduate students in a biochemistry teaching laboratory, isothermal titration calorimetry (ITC) is employed to determine the binding constants of lysozyme and its inhibitors, N-acetyl glucosamine trimer (NAG[subscript 3]) and monomer (NAG). The extremely weak binding of lysozyme/NAG is…

  14. Role of titrated low dose oral misoprostol solution in induction of labour

    Directory of Open Access Journals (Sweden)

    Sarvottma Antil

    2016-03-01

    Conclusions: For induction of labour in women with term gestation after cervical priming, low dose oral misoprostol solution in titrated doses and intravenous oxytocin were found to be comparable with each other in terms of labour outcomes, efficacy and adverse effects. [Int J Reprod Contracept Obstet Gynecol 2016; 5(3.000: 775-782

  15. Classification of calorimetric titration plots for alkyltrimethylammonium and alkylpyridinium cationic surfactants in aqueous solutions

    NARCIS (Netherlands)

    Bijma, K; Engberts, J.B.F.N.; Blandamer, M.J; Cullis, P.M.; Last, P.M.; Irlam, K.D.; Soldi, L.G.

    1997-01-01

    Calorimetric titration plots for deaggregation of micelles formed by alkylpyridinium and alkyltrimethylammonium surfactants are classified into three types, A, B and C, depending on the shape of the plot of the enthalpy of dilution as a function of surfactant concentration. For Type A plots the reco

  16. Reduction in anaesthetic drug consumption is correlated with mean titrated intra-operative Bispectral Index values.

    NARCIS (Netherlands)

    Ellerkmann, R.K.; Kreuer, S.; Wilhelm, W.; Ropcke, H.; Hoeft, A.; Bruhn, J.

    2006-01-01

    BACKGROUND: Several studies have shown a reduction in anaesthetic drug consumption with Bispectral Index (BIS) titration compared with standard clinical practice. However, the amount of reduction varied widely between 1% and 40%. We investigated the correlation between reduction in anaesthetic drug

  17. DETERMINATION OF WATER CONTENT IN PYROLYTIC TARS USING COULOMETRIC KARL-FISHER TITRATION

    Directory of Open Access Journals (Sweden)

    Lenka Jílková

    2017-02-01

    Full Text Available The liquid organic fraction of pyrolytic tar has a high energy value which makes possible its utilization as an energy source. However, before utilization, it is crucial to remove water from the liquid fraction. The presence of water reduces the energy value of pyrolytic tars. Water separation from the organic tar fraction is a complex process, since an emulsion can be readily formed. Therefore, after phase separation, it is important to know the residual water content in the organic phase and whether it is necessary to further dry it. The results presented in this manuscript focus on a water determination in liquid products from coal and biomass pyrolysis by a coulometric Karl‑Fischer titration. The Coulometric Karl‑Fischer titration is often used for a water content determination in gaseous, liquid and solid samples. However, to date, this titration method has not been used for a water determination in tars. A new water determination method, which has been tested on different types of tar, has been developed. The Coulometric Karl‑Fischer titration is suitable for tar samples with a water content not greater than 5 wt. %. The obtained experimental results indicate that the new introduced method can be used with a very good repeatability for a water content determination in tars.

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

    Science.gov (United States)

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

    2012-01-01

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

  19. Titration of a Solid Acid Monitored by X-Ray Diffraction

    Science.gov (United States)

    Dungey, Keenan E.; Epstein, Paul

    2007-01-01

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

  20. An ISFET-based microlitre titrator: integration of a chemical sensor—actuator system

    NARCIS (Netherlands)

    Schoot, van der Bart; Bergveld, Piet

    1985-01-01

    This paper describes the integration of pH-sensitive ISFETs with a coulometric pH-actuator system. The coulometric analyser is able to perform acid—base titrations in microlitre samples at high speed. Combination of chemical sensors with a corresponding actuator eliminates the need for frequent cali

  1. Titration of a Solid Acid Monitored by X-Ray Diffraction

    Science.gov (United States)

    Dungey, Keenan E.; Epstein, Paul

    2007-01-01

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

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

    NARCIS (Netherlands)

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

    1975-01-01

    Acidified aluminum nitrate solutions were titrated with alkali (NaOH or KOH) over a temperature range of 24°C to 90°C. A homogeneous distribution of added base was achieved by: (i) in situ decomposition of urea (90°C); and (ii) a novel method involving injection through a capillary submerged in the

  3. Classification of calorimetric titration plots for alkyltrimethylammonium and alkylpyridinium cationic surfactants in aqueous solutions

    NARCIS (Netherlands)

    Bijma, K; Engberts, J.B.F.N.; Blandamer, M.J; Cullis, P.M.; Last, P.M.; Irlam, K.D.; Soldi, L.G.

    1997-01-01

    Calorimetric titration plots for deaggregation of micelles formed by alkylpyridinium and alkyltrimethylammonium surfactants are classified into three types, A, B and C, depending on the shape of the plot of the enthalpy of dilution as a function of surfactant concentration. For Type A plots the

  4. An Exact Method to Determine the Conductivity of Aqueous Solutions in Acid-Base Titrations

    Directory of Open Access Journals (Sweden)

    Norma Rodríguez-Laguna

    2015-01-01

    Full Text Available Several works in the literature show that it is possible to establish the analytic equations to estimate the volume V of a strong base or a strong acid (Vb and Va, resp. being added to a solution of a substance or a mix of substances during an acid-base titration, as well as the equations to estimate the first derivative of the titration plot dpH/dV, and algebraic expressions to determine the buffer β capacity with dilution βdil. This treatment allows establishing the conditions of thermodynamic equilibria for all species within a system containing a mix of species from one or from various polyacid systems. The present work shows that it is possible to determine exactly the electric conductivity of aqueous solutions for these Brønsted acid-base titrations, because the functional relation between this property and the composition of the system in equilibrium is well known; this is achieved using the equivalent conductivity λi values of each of the ions present in a given system. The model employed for the present work confirms the experimental outcomes with the H2SO4, B(OH3, CH3COOH, and H3PO4 aqueous solutions’ titration.

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

    Science.gov (United States)

    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.

  6. Contributions to the petrography, geochemistry and geochronology (U-Pb and Sm-Nd) of the Paleoproterozoic effusive rocks from Iricoume Group, Amazonian Craton, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Suelen Nonata de Souza; Nascimento, Rielva Solimairy Campelo do, E-mail: suelen-marques@hotmail.com, E-mail: rielva@ufam.edu.br [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil). Inst. de Geociencias; Souza, Valmir da Silva; Dantas, Elton Luiz, E-mail: vsouza@unb.br, E-mail: elton@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Inst. de Geociencias; Valerio, Cristovao da Silva, E-mail: cristovao@igeo.ufrr.br [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil). Inst. de Geociencias

    2014-07-01

    The southernmost region of the Guyana shield, Amazonian craton, hosts large record of Paleoproterozoic effusive rocks of the Iricoume Group. They present remarkably well-preserved igneous textures and structures. The SiO{sub 2} contents reveal a bimodal association marked by a compositional gap between acid (SiO{sub 2} > 67 wt%) and intermediate (SiO{sub 2} < 57.7 wt%) rocks. The acid effusive rocks are rhyolites to rhyodacites with high SiO{sub 2}, alkali, Rb, Zr, Nb + Ta, La + Ce and 104 Ga/Al content and low Fe{sub 2}O{sub 3tot}, TiO{sub 2}, CaO, Sr and Co content. They exhibit subalkaline, metaluminous-to-peraluminous compositions, and geochemically compatible to A-type magmatism emplaced in post-collisional to within-plate tectonic settings. The intermediate rocks are andesitic/basalt to andesite relatively high contents of TiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3total}, MgO, CaO, Sr and Co; low SiO{sub 2}, K{sub 2}O, Rb, Zr, Nb + Ta, La + Ce. They have subalkaline and metaluminous geochemical composition and plot on within-plate basalt field. The acid rocks crystallized at 1882 ± 11 Ma in U-Pb analyses for LA-MC-ICPMS zircon data. The Sm-Nd isotopic data on all rocks reveal a Nd TDM model ages between 2.59 and 2.16 Ga and ε{sub Nd}(t) values between -5.78 and 0.03, indicate that the magmatic evolution was related to the reworking of older Paleoproterozoic at the Rhyacian-Siderian period, continental crust (Transamazonian crust-forming event) with some mixing with a limited amount mantle-derived magmas or with contamination by Archean crust. The petrographic, geochemical and geochronological data presented in this paper suggest a within-plate to post-collisional tectonic setting for the Iricoume volcanism, involving lower crust uplift and generation of basalt magma in an extensional regime. (author)

  7. Both group 4 capsule and lipopolysaccharide O-antigen contribute to enteropathogenic Escherichia coli resistance to human α-defensin 5.

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    Jenny-Lee Thomassin

    Full Text Available Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC are food-borne pathogens that colonize the small intestine and colon, respectively. To cause disease, these pathogens must overcome the action of different host antimicrobial peptides (AMPs secreted into these distinct niches. We have shown previously that EHEC expresses high levels of the OmpT protease to inactivate the human cathelicidin LL-37, an AMP present in the colon. In this study, we investigate the mechanisms used by EPEC to resist human α-defensin 5 (HD-5, the most abundant AMP in the small intestine. Quantitative PCR was used to measure transcript levels of various EPEC surface structures. High transcript levels of gfcA, a gene required for group 4 capsule (G4C production, were observed in EPEC, but not in EHEC. The unencapsulated EPEC ∆gfcA and EHEC wild-type strains were more susceptible to HD-5 than EPEC wild-type. Since the G4C is composed of the same sugar repeats as the lipopolysaccharide O-antigen, an -antigen ligase (waaL deletion mutant was generated in EPEC to assess its role in HD-5 resistance. The ∆waaL EPEC strain was more susceptible to HD-5 than both the wild-type and ∆gfcA strains. The ∆gfcA∆waaL EPEC strain was not significantly more susceptible to HD-5 than the ∆waaL strain, suggesting that the absence of -antigen influences G4C formation. To determine whether the G4C and -antigen interact with HD-5, total polysaccharide was purified from wild-type EPEC and added to the ∆gfcA∆waaL strain in the presence of HD-5. The addition of exogenous polysaccharide protected the susceptible strain against HD-5 killing in a dose-dependent manner, suggesting that HD-5 binds to the polysaccharides present on the surface of EPEC. Altogether, these findings indicate that EPEC relies on both the G4C and the -antigen to resist the bactericidal activity of HD-5.

  8. The contribution of gender-role orientation, work factors and home stressors to psychological well-being and sickness absence in male- and female-dominated occupational groups.

    Science.gov (United States)

    Evans, Olga; Steptoe, Andrew

    2002-02-01

    The associations of work stress, types of work and gender-role orientation with psychological well-being and sickness absence were investigated in a questionnaire survey of 588 male and female nurses and 387 male and female accountants. We hypothesised that health might be impaired among women working in the male-dominated occupation (accountancy), and men in the female-dominated occupation (nursing), but that effects might be moderated by job strain (perceptions of high demand and low control), work and home hassles, and traditional male (instrumentality) and female (expressivity) psychological characteristics. Responses were analysed from 172 female and 61 male nurses, and from 53 female and 81 male commercial accountants. Female accountants were more likely than other groups to have high anxiety scores on the Hospital Anxiety and Depression Scales, while male nurses had the highest rates of sickness absence. Male nurses and female accountants also reported more work-related hassles than did female nurses and male accountants. Men and women in the same occupation did not differ in job strain or job social support, but nurses reported greater job strain than accountants, due to higher ratings of demands and lower skill utilisation. After adjusting for age, sex, occupation, paid work hours and a measure of social desirability bias, risk of elevated anxiety was independently associated with higher job strain, lower job social support, more work hassles, more domestic responsibility, lower instrumentality and higher expressivity. The association between sex and anxiety was no longer significant after instrumentality had been entered into the regression model. Sickness absence of more than three days over the past 12 months was independently associated with higher job strain, more work hassles, lower instrumentality and higher expressivity. The results suggest that when men and women occupy jobs in which they are in the cultural and numerical minority, there may be

  9. Iron isotope compositions and origins of pyrites from the Turee Creek Group, Western Australia: the contribution of high-resolution femtosecond Laser Ablation -MC-ICP-MS

    Science.gov (United States)

    d'Abzac, F.; Beard, B. L.; Williford, K. H.; Valley, J. W.; Van Kranendonk, M. J.; Johnson, C.

    2013-12-01

    The Paleoproterozoic Great Oxidation Event (GOE) records a transition from an anoxic environment to a O2-bearing atmosphere, but its timing and duration remain unclear. High-spatial-resolution S isotope analyses by SIMS have shown that pyrite grains in the ~2.4Gy diamictites of the Meteorite Bore Member (MBM; Turee Creek Group, Western Australia), deposited during the GOE, contain evidence for a complex depositional and paragenetic history, including microbial sulfate reduction under low atmospheric O2 yet high seawater sulfate concentrations. The pyrites show various morphologies: euhedral, subhedral, anhedral, rounded, and zoned, where low- δ34S rounded cores may have high-δ34S euhedral/subhedral overgrowths [1]. New in-situ Fe isotope data by femtosecond laser ablation (fs-LA) analysis using Multi Collector ICP-MS on 118 pyrite grains within five rock samples previously analyzed for S isotopes documents δ56Fe values between -2.3‰ and +2.3‰. Transitional cherts at the base of the MBM record the highest δ56Fe values, >0.7‰. Within the upper mudstones/sandstones deposits, anhedral, rounded grains and zoned pyrite cores have a wide range of δ56Fe from -2.3‰ to +1.1‰ whereas euhedral grains and grains overgrowths have mainly positive δ56Fe values, up to +1.34‰, spread over narrower ranges in each sample (100°C [5, 6], in agreement with [1]. The δ34S gradient of highly negative to positive values from zoned pyrites cores to rims is well correlated with our observations of low-δ56Fe cores to positive δ56Fe rims, within the same set of grains, which supports the paragenesis described in [1]. This study demonstrates the importance of high resolution in-situ isotopic analysis for samples of complex histories and multiple isotopic components, and in the case of the GOE transition, document that a large variety of Fe pathways were active during the transition. 1. Williford, K.H., et al., Geochimica et Cosmochimica Acta, 2011. 75(19): p. 5686-5705. 2

  10. Web-based guided insulin self-titration in patients with type 2 diabetes: the Di@log study. Design of a cluster randomised controlled trial [TC1316

    Directory of Open Access Journals (Sweden)

    Kostense Piet J

    2009-06-01

    Full Text Available Abstract Background Many patients with type 2 diabetes (T2DM are not able to reach the glycaemic target level of HbA1c Methods/Design T2DM patients (n = 248, aged 35–75 years, with an HbA1c ≥ 7.0%, eligible for treatment with insulin and able to use the internet will be selected from general practices in two different regions in the Netherlands. Cluster randomisation will be performed at the level of general practices. Patients in the intervention group will use a self-developed internet programme to assist them in self-titrating insulin. The control group will receive usual care. Primary outcome is the difference in change in HbA1c between intervention and control group. Secondary outcome measures are quality of life, treatment satisfaction, diabetes self-efficacy and frequency of hypoglycaemic episodes. Results will be analysed according to the intention-to-treat principle. Discussion An internet intervention supporting self-titration of insulin therapy in T2DM patients is an innovative patient-centred intervention. The programme provides guided self-monitoring and evaluation of health and self-care behaviours through tailored feedback on input of glucose values. This is expected to result in a better performance of self-titration of insulin and consequently in the improvement of glycaemic control. The patient will be enabled to 'discover and use his or her own ability to gain mastery over his/her diabetes' and therefore patient empowerment will increase. Based on the self-regulation theory of Leventhal, we hypothesize that additional benefits will be achieved in terms of increases in treatment satisfaction, quality of life and self-efficacy. Trial registration Dutch Trial Register TC1316.

  11. Implementation of a web-based tool for patient medication self-management: the Medication Self-titration Evaluation Programme (Med-STEP for blood pressure control

    Directory of Open Access Journals (Sweden)

    Richard W Grant

    2013-12-01

    Full Text Available Background Informatics tools may help support hypertension management.Objective To design, implement and evaluate a web-based system for patient anti-hypertensive medication self-titration.Methods Study stages included: six focus groups (50 patients to identify barriers/facilitators to patient medication self-titration, software design informed by qualitative analysis of focus group responses and a six-month single-arm pilot study (20 patients to assess implementation feasibility.Results Focus groups emphasised patient need to feel confident that their own primary care providers were directly involved and approved of the titration protocol. Physicians required 3.3 ± 2.8 minutes/patient to create individualised six-step medication pathways for once-monthly blood pressure evaluations. Pilot participants (mean age of 51.5 ± 11 years, 45% women, mean baseline blood pressure 139/84 ± 12.2/7.5 mmHg had five medication increases, two non-adherence self-reports, 52months not requiring medication changes, 24 skipped months and 17 months with no evaluations due to technical issues. Four pilot patients dropped out before study completion. From baseline to study completion, blood pressure decreased among the 16 patients remaining in the study (8.0/4.7 mmHg, p = 0.03 for both systolic and diastolic pressures.Conclusions Lessons learned included the benefit of qualitative patient analysis prior to system development and the feasibility of physicians designing individual treatment pathways. Any potential clinical benefits were offset by technical problems, the tendency for patients to skip their monthly self-evaluations and drop outs. To be more widely adopted such systems must effectively generalise to a wider range of patients and be integrated into clinical workflow.

  12. Do geriatrics require dose titration for antidiabetic agents?

    Directory of Open Access Journals (Sweden)

    R Shastry

    2013-01-01

    Full Text Available Objective: To evaluate the antidiabetic drug dosage differences between geriatric and nongeriatric diabetics with reference to duration of disease and creatinine clearance (Crcl. Materials and Methods: Prospective study conducted for 6 months in a tertiary care hospital. Patients with type 2 diabetes mellitus were grouped into geriatric (age ≥60 years and nongeriatric (age <60 years. Patients′ demographic data, duration of diabetes, medication, and serum creatinine were recorded. Crcl was calculated using Cockcroft-Gault formula. Doses of sulfonylureas (SU were converted into equivalent doses, taking glibenclamide as standard. Univariate analysis was done for comparison of drug doses between groups. Result: A total of 320 geriatric and 157 nongeriatric diabetics completed the study. The duration of diabetes and Crcl adjusted dose reduction of glibenclamide (mean dose: Geriatrics 7.2±0.4 mg, nongeriatrics 9.6±0.7 mg; P=0.01 and gliclazide (mean dose: Geriatrics 85.5±11.5 mg, nongeriatrics 115.3±32.7 mg; P=0.42 was 25%, glimepiride (mean dose: Geriatrics 1.62±0.13 mg, nongeriatrics 2.1±0.18 mg; P=0.06 was 22%. Glipizide did not require dose reduction. Mean converted equivalent dose of sulfonylurea monotherapy was significantly lower in geriatrics than nongeriatrics (3.2±0.5 vs 6.4±1.02 mg; P=0.01 and showed 50% dose reduction. Mean dose of metformin was lower in geriatrics (901±32.2 mg vs 946.7±45.8 mg; P=0.45 and showed 5% reduction in dosage. There was no difference in the mean drug doses of thiazolidinediones and insulin between the groups. Conclusion: A substantial dose reduction of glibenclamide (25%, gliclazide (25%, glimepiride (22%, and metformin (5% in geriatrics compared to nongeriatrics was observed. Smaller dosage formulations like 0.75 mg glibenclamide, 0.5 mg glimepiride, 20 mg gliclazide, and 250 mg metformin may be of value in geriatric diabetic practice.

  13. Collecting Variable-concentration Isothermal Titration Calorimetry Datasets in Order to Determine Binding Mechanisms

    Science.gov (United States)

    Freiburger, Lee A.; Mittermaier, Anthony K.; Auclair, Karine

    2011-01-01

    Isothermal titration calorimetry (ITC) is commonly used to determine the thermodynamic parameters associated with the binding of a ligand to a host macromolecule. ITC has some advantages over common spectroscopic approaches for studying host/ligand interactions. For example, the heat released or absorbed when the two components interact is directly measured and does not require any exogenous reporters. Thus the binding enthalpy and the association constant (Ka) are directly obtained from ITC data, and can be used to compute the entropic contribution. Moreover, the shape of the isotherm is dependent on the c-value and the mechanistic model involved. The c-value is defined as c = n[P]tKa, where [P]t is the protein concentration, and n is the number of ligand binding sites within the host. In many cases, multiple binding sites for a given ligand are non-equivalent and ITC allows the characterization of the thermodynamic binding parameters for each individual binding site. This however requires that the correct binding model be used. This choice can be problematic if different models can fit the same experimental data. We have previously shown that this problem can be circumvented by performing experiments at several c-values. The multiple isotherms obtained at different c-values are fit simultaneously to separate models. The correct model is next identified based on the goodness of fit across the entire variable-c dataset. This process is applied here to the aminoglycoside resistance-causing enzyme aminoglycoside N-6'-acetyltransferase-Ii (AAC(6')-Ii). Although our methodology is applicable to any system, the necessity of this strategy is better demonstrated with a macromolecule-ligand system showing allostery or cooperativity, and when different binding models provide essentially identical fits to the same data. To our knowledge, there are no such systems commercially available. AAC(6')-Ii, is a homo-dimer containing two active sites, showing cooperativity between

  14. Collecting variable-concentration isothermal titration calorimetry datasets in order to determine binding mechanisms.

    Science.gov (United States)

    Freiburger, Lee A; Mittermaier, Anthony K; Auclair, Karine

    2011-04-07

    Isothermal titration calorimetry (ITC) is commonly used to determine the thermodynamic parameters associated with the binding of a ligand to a host macromolecule. ITC has some advantages over common spectroscopic approaches for studying host/ligand interactions. For example, the heat released or absorbed when the two components interact is directly measured and does not require any exogenous reporters. Thus the binding enthalpy and the association constant (Ka) are directly obtained from ITC data, and can be used to compute the entropic contribution. Moreover, the shape of the isotherm is dependent on the c-value and the mechanistic model involved. The c-value is defined as c = n[P]tKa, where [P]t is the protein concentration, and n is the number of ligand binding sites within the host. In many cases, multiple binding sites for a given ligand are non-equivalent and ITC allows the characterization of the thermodynamic binding parameters for each individual binding site. This however requires that the correct binding model be used. This choice can be problematic if different models can fit the same experimental data. We have previously shown that this problem can be circumvented by performing experiments at several c-values. The multiple isotherms obtained at different c-values are fit simultaneously to separate models. The correct model is next identified based on the goodness of fit across the entire variable-c dataset. This process is applied here to the aminoglycoside resistance-causing enzyme aminoglycoside N-6'-acetyltransferase-Ii (AAC(6')-Ii). Although our methodology is applicable to any system, the necessity of this strategy is better demonstrated with a macromolecule-ligand system showing allostery or cooperativity, and when different binding models provide essentially identical fits to the same data. To our knowledge, there are no such systems commercially available. AAC(6')-Ii, is a homo-dimer containing two active sites, showing cooperativity between

  15. A dose titration study on the effect of virginiamycin on gilt/sow and piglet performance.

    Science.gov (United States)

    Kantas, D; Vassilopoulos, V; Kyriakis, S C; Saoulidis, K

    1998-11-01

    Virginiamycin (VM), a compound with proven performance-promoting properties in pigs, can also be considered as sow performance enhancer. The present dose titration study investigates the long-term effects of VM on gilt/sow and litter performance. A total of 140 healthy gilts, in 35 sets of 2 + 2 siblings each, were used in this trial; gilts in each set were randomly allocated to the four treatments (35 gilts per each treatment group): VM0 = negative control, virginiamycin 0 mg/kg, VM20 = virginiamycin 20 mg/kg, VM40 = virginiamycin 40 mg/kg and VM60 = virginiamycin 60 mg/kg of feed. VM was added to the gilt/sow feed for a period starting from 6 months of age up to conception of the fourth parity, covering three complete breeding cycles (pregnancy, lactation and weaning-to-conception interval). The feed given did not contain any other antibacterial agent or performance enhancer. Piglets were given exactly the same quantity of creep feed from the fifth day onwards; it did not contain any antibacterial agent or performance enhancer. The lactation period was the same in all gilts/sows (21 days). Results indicate that VM supplementation of the feed improved gilt/sow performance by: (i) increasing (P < 0.05) the mean body weight at each farrowing, (ii) decreasing (P < 0.05) the mean weight loss from farrowing to weaning, and (iii) decreasing (P < 0.05) the mean weaning-to-conception intervals. VM supplementation of gilt/sow feed also resulted in improved litter size and litter performance in terms of: (i) a higher (P < 0.05) mean number of piglets born alive at each birth, (ii) a higher (P < 0.05) mean number of piglets weaned, (iii) a higher (P < 0.05) mean piglet body weight at each birth, and (iv) a higher (P < 0.05) mean piglet body weight at each weaning. These beneficial effects of VM were more pronounced in the VM40 group.

  16. 2007 status of climate change: Mitigation of Climate Change. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Summary for Policy-makers; Bilan 2007 des changements climatiques: l'attenuation des changements climatiques. Contribution du Groupe de travail 3 au quatrieme rapport d'evaluation du Groupe d'Experts Intergouvernemental sur l'Evolution du Climat (GIEC). Resume a l'attention des decideurs

    Energy Technology Data Exchange (ETDEWEB)

    Barker, T.; Bashmakov, I.; Bernstein, L.; Bogner, J.; Bosch, P.; Dave, R.; Davidson, O.; Fisher, B.; Grubb, M.; Gupta, S.; Halsnaes, K.; Heij, B.; Kahn Ribeiro, S.; Kobayashi, S.; Levine, M.; Martino, D.; Masera Cerutti, O.; Metz, B.; Meyer, L.; Nabuurs, G.J.; Najam, A.; Nakicenovic, N.; Holger Rogner, H.; Roy, J.; Sathaye, J.; Schock, R.; Shukla, P.; Sims, R.; Smith, P.; Swart, R.; Tirpak, D.; Urge-Vorsatz, D.; Dadi, Z

    2007-07-01

    The Working Group III contribution to the IPCC Fourth Assessment Report (AR4) focuses on new literature on the scientific, technological, environmental, economic and social aspects of mitigation of climate change, published since the IPCC Third Assessment Report (TAR) and the Special Reports on CO{sub 2} Capture and Storage (SRCCS) and on Safeguarding the Ozone Layer and the Global Climate System (SROC).The main aim of this summary report is to assess options for mitigating climate change. Several aspects link climate change with development issues. This report explores these links in detail, and illustrates where climate change and sustainable development are mutually reinforcing. Economic development needs, resource endowments and mitigative and adaptive capacities differ across regions. There is no one-size-fits-all approach to the climate change problem, and solutions need to be regionally differentiated to reflect different socio-economic conditions and, to a lesser extent, geographical differences. Although this report has a global focus, an attempt is made to differentiate the assessment of scientific and technical findings for the various regions. Given that mitigation options vary significantly between economic sectors, it was decided to use the economic sectors to organize the material on short- to medium-term mitigation options. Contrary to what was done in the Third Assessment Report, all relevant aspects of sectoral mitigation options, such as technology, cost, policies etc., are discussed together, to provide the user with a comprehensive discussion of the sectoral mitigation options. The report is organised into six sections after the introduction: - Greenhouse gas (GHG) emission trends; - Mitigation in the short and medium term, across different economic sectors (until 2030); - Mitigation in the long-term (beyond 2030); - Policies, measures and instruments to mitigate climate change; - Sustainable development and climate change mitigation; - Gaps in

  17. 镧、镨及钐与氨基酸配合物的滴定量热研究%Study on Complexes of La3+,Pr3+,Sm3+ with Amino Acids by Titration Calorimeter

    Institute of Scientific and Technical Information of China (English)

    叶刚; 汪存信; 王志勇; 刘欲文; 屈松生

    2001-01-01

    用滴定量热法测定了298.15K下稀土镧(Ⅲ)、镨(Ⅲ)及钐(Ⅲ)离子与8种氨基酸配合物的稳定常数及反应焓变, 并由此推出反应的吉布斯自由能变化和熵变. 实验结果表明:焓变是配合反应的主要驱动力;氨基酸侧链R基极性的增加对配合反应有阻碍作用,而氨基酸中环参与配合反应则有助于提高配合物的稳定性.%The stability constants and thermodynamic functions for complexes of La3+,Pr3+,Sm3+ with some amino acids have been determined by titration calorimeter at 298.15 K. The optimum condition of forming complexes has been also discussed,and regulating the pH of system around 6.0 the complexes will exist stablely in system.The enthalpy change makes a predominant contribution to the stability of these complexes. The increase of the polarity of R group in amino acids(R-CH(NH+3)COO-) resists to make complexes. The ring in amino acid associated with La3+,Pr3+or Sm3+ helps to enhance the stability of complexes.

  18. Caracterização ácido-base da superfície de espécies mistas da alga Spirulina através de titulação potenciométrica e modelo de distribuição de sítios discretos Acid base characterization of the surface of mixed species of algae Spirulin by potentiometric titration and discrete site distribution model

    Directory of Open Access Journals (Sweden)

    Elizabete C. de Lima

    1999-09-01

    Full Text Available Acid base properties of mixed species of the microalgae Spirulina were studied by potentiometric titration in medium of 0.01 and 0.10 mols L-1 NaNO3 at 25.0±0.10 C using modified Gran functions or nonlinear regression techniques for data fitting. The discrete site distribution model was used, permitting the characterization of five classes of ionizable sites in both ionic media. This fact suggests that the chemical heterogeneity of the ionizable sites on the cell surface plays a major role on the acid-base properties of the suspension in comparison to electrostatic effects due to charge-charge interactions. The total of ionizable sites were 1.75±0.10 and 1.86±0.20 mmolsg-1 in ionic media of 0.01 and 0.10 mols L-1 NaNO3, respectively. A major contribution of carboxylic groups was observed with an average 34 and 22% of ionizable sites being titrated with conditional pcKa of 4.0 and 5.4, respectively. The remaining 44% of ionizable sites were divided in three classes with averaged conditional pcKa of 6.9, 8.7 and 10.12, which may be assigned respectively to imidazolic, aminic, and phenolic functionalities.

  19. 滴定分析教学的好帮手"Titration simulator"

    Institute of Scientific and Technical Information of China (English)

    "Titration; simulator"--Good; assistant; for; titration; analysis

    2005-01-01

      Titration simulator(滴定模拟器)软件是专门为滴定分析而设计的教学软件,它短小精悍,简洁实用,可以从Internet网上免费下载,网址为:http://www.chemonline.net/Truechemsoft/downsoft.asp?softID=1565该软件所占容量仅为72KB,是学生训练及化学教师的好助手.笔者在教学中尝试运用该软件辅助教学,效果良好,现将Titration simulator软件的主要功能、应用简要介绍如下:……

  20. Probing the thermodynamics of protein-lipid interactions by isothermal titration calorimetry.

    Science.gov (United States)

    Swamy, Musti J; Sankhala, Rajeshwer S

    2013-01-01

    Isothermal titration calorimetry is a highly sensitive technique for the study of molecular interactions. This method has been applied quite extensively to investigate the interaction of proteins with small ligands, other proteins, and nucleic acids as well as with drugs and metal ions. In this chapter, we describe the application of ITC for the investigation of thermodynamics of protein-lipid interaction. A number of parameters such as enthalpy of binding (ΔH), entropy of binding (ΔS), association constant (K (a)), binding stoichiometry (n), and free energy of binding (ΔG) can be obtained from a single calorimetric titration, providing a complete thermodynamic characterization of the interaction. The method is described in detail taking the major protein of the bovine seminal plasma, PDC-109, which exhibits a high preference for interaction with choline-containing lipids, as an example. The method can be applied to investigate the thermodynamics of the interaction of other soluble proteins with lipid membranes.

  1. Higher Order Inclusion Complexes and Secondary Interactions Studied by Global Analysis of Calorimetric Titrations

    DEFF Research Database (Denmark)

    Schönbeck, Jens Christian Sidney; Holm, René; Westh, Peter

    2012-01-01

    ). The results are validated by a 13C NMR titration and negative controls with a bile salt with no secondary binding site (glycocholate) (K = 2.96 ± 0.01 × 103 M–1). The method proved useful for detailed analysis of ITC data and may strengthen its use as a tool for studying molecular systems by advanced binding......This paper investigates the use of isothermal titration calorimetry (ITC) as a tool for studying molecular systems in which weaker secondary interactions are present in addition to a dominant primary interaction. Such systems are challenging since the signal pertaining to the stronger primary...... interaction tends to overshadow the signal from the secondary interaction. The methodology presented here enables a complete and precise thermodynamic characterization of both the primary and the weaker secondary interaction, exemplified by the binding of β-cyclodextrin to the primary and secondary binding...

  2. Monosegemented flow potentiometric titration for the determination of chloride in milk and wine

    Directory of Open Access Journals (Sweden)

    Vieira Jonas A.

    2003-01-01

    Full Text Available An automated flow potentiometric titration procedure for the determination of chloride in milk and wine exploiting the monosegmented flow approach is described. The flow network was designed based on a six-way solenoid valve, controlled by a microcomputer running software written in VisualBasic 3.0, allowing selection of the titration conditions. An Ag2S tubular electrode selective for Cl- and a conventional Ag/AgCl electrode were employed as indicator and reference, respectively. An algorithm based on the potential difference between two subsequent titrant additions was developed, allowing to reach the end point in less than 10 attempts, with a precision better than 1.0%. The proposed system was evaluated by determining chloride in milk and wine, using a standard AgNO3 solution as titrant. Accuracy was ascertained by comparing the results with those obtained using the AOAC procedure. No significant difference at a 95% confidence level was observed.

  3. Determination of the catalytic activity of binuclear metallohydrolases using isothermal titration calorimetry.

    Science.gov (United States)

    Pedroso, Marcelo M; Ely, Fernanda; Lonhienne, Thierry; Gahan, Lawrence R; Ollis, David L; Guddat, Luke W; Schenk, Gerhard

    2014-03-01

    Binuclear metallohydrolases are a large and diverse family of enzymes that are involved in numerous metabolic functions. An increasing number of members find applications as drug targets or in processes such as bioremediation. It is thus essential to have an assay available that allows the rapid and reliable determination of relevant catalytic parameters (k cat, K m, and k cat/K m). Continuous spectroscopic assays are frequently only possible by using synthetic (i.e., nonbiological) substrates that possess a suitable chromophoric marker (e.g., nitrophenol). Isothermal titration calorimetry, in contrast, affords a rapid assay independent of the chromophoric properties of the substrate-the heat associated with the hydrolytic reaction can be directly related to catalytic properties. Here, we demonstrate the efficiency of the method on several selected examples of this family of enzymes and show that, in general, the catalytic parameters obtained by isothermal titration calorimetry are in good agreement with those obtained from spectroscopic assays.

  4. Implementation of a titrated oxygen protocol in the out-of-hospital setting.

    Science.gov (United States)

    Bosson, Nichole; Gausche-Hill, Marianne; Koenig, William

    2014-08-01

    Oxygen is one of the most frequently-used therapeutic agents in medicine and the most commonly administered drug by prehospital personnel. There is increasing evidence of harm with too much supplemental oxygen in certain conditions, including stroke, chronic obstructive pulmonary disease (COPD), neonatal resuscitations, and in postresuscitation care. Recent guidelines published by the British Thoracic Society (BTS) advocate titrated oxygen therapy, but these guidelines have not been widely adapted in the out-of-hospital setting where high-flow oxygen is the standard. This report is a description of the implementation of a titrated oxygen protocol in a large urban-suburban Emergency Medical Services (EMS) system and a discussion of the practical application of this out-of-hospital protocol.

  5. Self-titrating anticoagulant nanocomplexes that restore homeostatic regulation of the coagulation cascade.

    Science.gov (United States)

    Lin, Kevin Y; Lo, Justin H; Consul, Nikita; Kwong, Gabriel A; Bhatia, Sangeeta N

    2014-09-23

    Antithrombotic therapy is a critical portion of the treatment regime for a number of life-threatening conditions, including cardiovascular disease, stroke, and cancer; yet, proper clinical management of anticoagulation remains a challenge because existing agents increase the propensity for bleeding in patients. Here, we describe the development of a bioresponsive peptide-polysaccharide nanocomplex that utilizes a negative feedback mechanism to self-titrate the release of anticoagulant in response to varying levels of coagulation activity. This nanoscale self-titrating activatable therapeutic, or nanoSTAT, consists of a cationic thrombin-cleavable peptide and heparin, an anionic polysaccharide and widely used clinical anticoagulant. Under nonthrombotic conditions, nanoSTATs circulate inactively, neither releasing anticoagulant nor significantly prolonging bleeding time. However, in response to life-threatening pulmonary embolism, nanoSTATs locally release their drug payload and prevent thrombosis. This autonomous negative feedback regulator may improve antithrombotic therapy by increasing the therapeutic window and decreasing the bleeding risk of anticoagulants.

  6. Titratable Macroions in Multivalent Electrolyte Solutions: Strong Coupling Dressed Ion Approach

    CERN Document Server

    Adzic, Natasa

    2016-01-01

    We present a theoretical description of the effect of polyvalent ions on the interaction between titratable macro-ions. The model system consists of two point-like macro-ions with dissociable sites, immersed in an asymmetric ionic mixture of monovalent and polyvalent salts. We formulate a {\\em dressed ion strong coupling theory}, based on the decomposition of the asymmetric ionic mixture into a weakly electrostatically coupled monovalent salt, and into polyvalent ions that are strongly electrostatically coupled to the titratable macro-ions. The charge of the macroions is not considered as fixed, but is allowed to respond to local bathing solution parameters (electrostatic potential, $pH$ of the solution, salt concentration) through a simple {\\em charge regulation} model. The approach presented, yielding an effective polyvalent-ion mediated interaction between charge-regulated macro-ions at various solution conditions, describes the strong coupling equivalent of the Kirkwood-Schumaker interaction.

  7. Rapid determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration

    Institute of Scientific and Technical Information of China (English)

    XIAO Jun-ping; WANG Xue-feng; ZHOU Qing-xiang; FAN Xiao-yuan; SU Xian-fa; Bai Hua-hua; DUAN Hai-jing

    2007-01-01

    A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol had an excellent linear relationship over the range of 4.82×10-6 -9.65×10-3 mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%.

  8. Determinations of Carbon Dioxide by Titration: New Experiments for General, Physical, and Quantitative Analysis Courses

    Science.gov (United States)

    Crossno, S. K.; Kalbus, L. H.; Kalbus, G. E.

    1996-02-01

    The determination of mixtures containing NaOH and Na2CO3 or Na2CO3 and NaHCO3 by titration is a common experiment in a Quantitative Analysis course. This determination can be adapted for the analysis of CO2 within a sample. The CO2 is released and absorbed in a solution containing excess NaOH. Titration with standard HCl leads to the determination of CO2 present in the sample. A number of interesting experiments in Quantitative Analysis, General and/or Physical Chemistry have been developed. Among these are the following determinations: CO2 content in carbonated beverages, carbonate and bicarbonate in various real life samples, and the molecular weight of CO2.

  9. Determination of the aggregation number for micelles by isothermal titration calorimetry

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Holm, Rene; Westh, Peter

    2014-01-01

    Isothermal titration calorimetry (ITC) has previously been applied to estimate the aggregation number (n), Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of micellization. However, some difficulties of micelle characterization by ITC still remain; most micelles have aggregation numbers...... > 4 and its mathematical implementation is therefore not straight-forward. It seems as if all of these difficulties can be traced back to the aggregation number. In this work a new principle of data quantification is derived which is easy to apply, interpret and will provide statistical reliable...... insight into optimal design of titration protocols for micelle characterization. By applying the new method, the aggregation number of sodium dodecyl sulphate and glycochenodeoxycholate was determined at concentrations around their critical micelle concentration (CMC)...

  10. Electroanalytical measurements without electrolytes: conducting polymers as probes for redox titration in non-conductive organic media.

    Science.gov (United States)

    Lange, Ulrich; Mirsky, Vladimir M

    2012-09-26

    Electroanalytical methods have been applied only in conducting media. An application of conducting polymers allows to overcome this limitation. If such material is in electrochemical equilibrium with dissolved redox active species, its electrical conductivity depends on the redox potential of these species. Therefore, conductometric measurements with conducting polymers can provide about the same information as classical redox electrodes. The approach was applied for redox titration. Equivalent points obtained by this titration in aqueous and organic electrolytes were identical. Then the approach was applied for determination of bromine number by redox titration in non-conducting organic phase.

  11. Positive End-expiratory Pressure Titration after Alveolar Recruitment Directed by Electrical Impedance Tomography

    Institute of Scientific and Technical Information of China (English)

    Yun Long; Da-Wei Liu; Huai-Wu He; Zhan-Qi Zhao

    2015-01-01

    Background:Electrical impedance tomography (EIT) is a real-time bedside monitoring tool,which can reflect dynamic regional lung ventilation.The aim of the present study was to monitor regional gas distribution in patients with acute respiratory distress syndrome (ARDS) during positive-end-expiratory pressure (PEEP) titration using EIT.Methods:Eighteen ARDS patients under mechanical ventilation in Department of Critical Care Medicine of Peking Union Medical College Hospital from January to April in 2014 were included in this prospective observational study.After recruitment maneuvers (RMs),decremental PEEP titration was performed from 20 cmH2O to 5 cmH2O in steps of 3 cmH2O every 5-10 min.Regional over-distension and recruitment were monitored with EIT.Results:After RMs,patient with arterial blood oxygen partial pressure (PaO2) + carbon dioxide partial pressure (PaCO2) >400 mmHg with 100% of fractional inspired oxygen concentration were defined as RM responders.Thirteen ARDS patients was diagnosed as responders whose PaO2 + PaCO2 were higher than nonresponders (419 ± 44 mmHg vs.170 ± 73 mmHg,P < 0.0001).In responders,PEEP mainly increased recruited pixels in dependent regions and over-distended pixels in nondependent regions.PEEP alleviated global inhomogeneity of tidal volume and end-expiratory lung volume.PEEP levels without significant alveolar derecruitment and over-distension were identified individually.Conclusions:After RMs,PEEP titration significantly affected regional gas distribution in lung,which could be monitored with EIT.EIT has the potential to optimize PEEP titration.

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

    Science.gov (United States)

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

    2015-03-01

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

  13. Self-Titrating Anticoagulant Nanocomplexes That Restore Homeostatic Regulation of the Coagulation Cascade

    OpenAIRE

    Lin, Kevin Y.; Lo, Justin H.; Consul, Nikita; Kwong, Gabriel A.; Bhatia, Sangeeta N.

    2014-01-01

    Antithrombotic therapy is a critical portion of the treatment regime for a number of life-threatening conditions, including cardiovascular disease, stroke, and cancer; yet, proper clinical management of anticoagulation remains a challenge because existing agents increase the propensity for bleeding in patients. Here, we describe the development of a bioresponsive peptide–polysaccharide nanocomplex that utilizes a negative feedback mechanism to self-titrate the release of anticoagulant in resp...

  14. 40 CFR Appendix A to Part 425 - Potassium Ferricyanide Titration Method

    Science.gov (United States)

    2010-07-01

    ... chloride buffer, pH 9.3: Dissolve 200 g. ammonium chloride in approximately 500 ml. distilled water, add.... Adjust the sample to pH 8.5-9.5 with 6N HC1. 3. Add 20 ml. of 6M ammonium chloride buffer (pH 9.3), 1 ml... with barium chloride. Thiosulfate is not titrated under the conditions of the determination...

  15. The coulometric titration of acids and bases in m-cresol medium

    NARCIS (Netherlands)

    Bos, M.; Dahmen, E.A.M.F.

    1974-01-01

    A method is described for the coulometric titration of acids and bases in the solvent m-cresol. The method is suitable for bases with pKa values greater than 11 in m-cresol, or for acids with pKa values below 13 in m-cresol. Amounts of 5–50 μeq of acid or base can be determined with a relative

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. Isothermal Titration Calorimetry in Nanoliter Droplets with Sub-Second Time Constants

    OpenAIRE

    2011-01-01

    We reduced the reaction volume in microfabricated suspended-membrane titration calorimeters to nanoliter droplets and improved the sensitivities to below a nanowatt with time constants of around 100ms, The device performance was characterized using exothermic acid-base neutralizations and a detailed numerical model. The finite element based numerical model allowed us to determine the sensitivities within 1% and the temporal dynamics of the temperature rise in neutralization reactions as a fun...

  19. Elucidating thermodynamic parameters for electron transfer proteins using isothermal titration calorimetry: application to the nitrogenase Fe protein.

    Science.gov (United States)

    Sørlie, Morten; Chan, Jeannine M; Wang, Haijang; Seefeldt, Lance C; Parker, Vernon D

    2003-05-01

    Establishing thermodynamic parameters for electron transfer reactions involving redox proteins is essential for a complete description of these important reactions. While various methods have been developed for measuring the Gibbs free energy change (Delta G(HR) or E(m)) for the protein half-reactions, deconvolution of the respective contributions of enthalpy (Delta H(HR)) and entropy (Delta S(HR)) changes is much more challenging. In the present work, an approach is developed using isothermal titration calorimetry (ITC) that allows accurate determination of all of these thermodynamic parameters for protein electron transfer half-reactions. The approach was validated for essentially irreversible and reversible electron transfer reactions between well-characterized mediators and between mediators and the protein cytochrome c. In all cases, the measured thermodynamic parameters were in excellent agreement with parameters determined by electrochemical methods. Finally, the calorimetry approach was used to determine thermodynamic parameters for electron transfer reactions of the nitrogenase Fe protein [4Fe-4S](2+/+) couple in the absence or presence of MgADP or MgATP. The E(m) value was found to change from -290 mV in the absence of nucleotides to -381 mV with MgATP and -423 mV with MgADP, consistent with earlier values. For the first time, the enthalpy (Delta H(HR)) and entropy (Delta S(HR)) contributions for each case were established, revealing shifts in the contribution of each thermodynamic parameter induced by nucleotide binding. The results are discussed in the context of current models for electron transfer in nitrogenase.

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

    Science.gov (United States)

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

    2014-01-01

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

  1. Role of DNA binding sites and slow unbinding kinetics in titration-based oscillators

    Science.gov (United States)

    Karapetyan, Sargis; Buchler, Nicolas E.

    2015-12-01

    Genetic oscillators, such as circadian clocks, are constantly perturbed by molecular noise arising from the small number of molecules involved in gene regulation. One of the strongest sources of stochasticity is the binary noise that arises from the binding of a regulatory protein to a promoter in the chromosomal DNA. In this study, we focus on two minimal oscillators based on activator titration and repressor titration to understand the key parameters that are important for oscillations and for overcoming binary noise. We show that the rate of unbinding from the DNA, despite traditionally being considered a fast parameter, needs to be slow to broaden the space of oscillatory solutions. The addition of multiple, independent DNA binding sites further expands the oscillatory parameter space for the repressor-titration oscillator and lengthens the period of both oscillators. This effect is a combination of increased effective delay of the unbinding kinetics due to multiple binding sites and increased promoter ultrasensitivity that is specific for repression. We then use stochastic simulation to show that multiple binding sites increase the coherence of oscillations by mitigating the binary noise. Slow values of DNA unbinding rate are also effective in alleviating molecular noise due to the increased distance from the bifurcation point. Our work demonstrates how the number of DNA binding sites and slow unbinding kinetics, which are often omitted in biophysical models of gene circuits, can have a significant impact on the temporal and stochastic dynamics of genetic oscillators.

  2. Role of DNA binding sites and slow unbinding kinetics in titration-based oscillators.

    Science.gov (United States)

    Karapetyan, Sargis; Buchler, Nicolas E

    2015-12-01

    Genetic oscillators, such as circadian clocks, are constantly perturbed by molecular noise arising from the small number of molecules involved in gene regulation. One of the strongest sources of stochasticity is the binary noise that arises from the binding of a regulatory protein to a promoter in the chromosomal DNA. In this study, we focus on two minimal oscillators based on activator titration and repressor titration to understand the key parameters that are important for oscillations and for overcoming binary noise. We show that the rate of unbinding from the DNA, despite traditionally being considered a fast parameter, needs to be slow to broaden the space of oscillatory solutions. The addition of multiple, independent DNA binding sites further expands the oscillatory parameter space for the repressor-titration oscillator and lengthens the period of both oscillators. This effect is a combination of increased effective delay of the unbinding kinetics due to multiple binding sites and increased promoter ultrasensitivity that is specific for repression. We then use stochastic simulation to show that multiple binding sites increase the coherence of oscillations by mitigating the binary noise. Slow values of DNA unbinding rate are also effective in alleviating molecular noise due to the increased distance from the bifurcation point. Our work demonstrates how the number of DNA binding sites and slow unbinding kinetics, which are often omitted in biophysical models of gene circuits, can have a significant impact on the temporal and stochastic dynamics of genetic oscillators.

  3. Interaction of diethyl aniline methylphosphonate with DNA: Spectroscopic and isothermal titration calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lu Yan, E-mail: yanlu2001@sohu.co [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China); Xu Meihua; Wang Gongke; Zheng Yun [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China)

    2011-05-15

    In this study the diethyl aniline methylphosphonate (DAM) was synthesized, the interaction of DAM with ct-DNA has been investigated by fluorescence spectra, UV spectra, molecular modeling and isothermal titration calorimetry (ITC). The binding constant of DAM to ct-DNA calculated from both isothermal titration calorimetry and fluorescence spectra were found to be in the 10{sup 4} M{sup -1} range. According to the ethidium bromide displacement studies, UV spectra and isothermal titration calorimetry experimental results, it can be concluded that DAM is an intercalator that can slide into the G-C rich region of ct-DNA. Furthermore, the results obtained from molecular modeling corroborated the experimental results obtanied from spectroscopic and ITC investigations. At the same time, fluorescence spectra suggested that the mechanism of the interaction of DAM to ct-DNA was a static enhancing type. ITC data showed that ct-DNA/DAM binding is enthalpy controlled. - Research highlights: The interaction of DAM with ct-DNA is a static enhancing type. DAM can slide into the G-C rich region of ct-DNA. The binding of DAM to ct-DNA is enthalpy controlled. The hydrogen bonding forces play an essential role in the binding process.

  4. Consensus statement: octreotide dose titration in secretory diarrhea. Diarrhea Management Consensus Development Panel.

    Science.gov (United States)

    Harris, A G; O'Dorisio, T M; Woltering, E A; Anthony, L B; Burton, F R; Geller, R B; Grendell, J H; Levin, B; Redfern, J S

    1995-07-01

    Octreotide is an effective therapeutic option in controlling secretory diarrhea of varied etiology. However, marked patient-to-patient differences in the antidiarrheal effects necessitate titration of octreotide dose in individual patients to achieve optimal symptom control. A consensus development panel established guidelines for octreotide dose titration in patients with secretory diarrhea. Overall, the panel recommended an aggressive approach in selecting the initial octreotide dose and in making subsequent dose escalations in patients with secretory diarrhea due to gastrointestinal tumors (eg, carcinoids, VIPomas), AIDS, dumping syndrome, short bowel syndrome, radiotherapy, or chemotherapy. To avoid hypoglycemia in patients with diabetes mellitus-associated secretory diarrhea, the panel recommended a low initial octreotide dose and a conservative titration regimen with close monitoring a blood glucose levels. The end point of therapy should focus on a reduction in diarrhea (frequency of bowel movements or stool volume) rather than normalization of hormonal profile. Overall, octreotide is well tolerated; principal side effects are transient injection site pain and gastrointestinal discomfort. For many patients with secretory diarrhea, octreotide therapy is expected to improve the overall health and quality of life and in the long run will lessen health care costs.

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

    Science.gov (United States)

    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.

  6. The development of a continuous isothermal titration calorimetric method for equilibrium studies.

    Science.gov (United States)

    Markova, Natalia; Hallén, Dan

    2004-08-01

    A continuous isothermal titration calorimetry (cITC) method for microcalorimeters has been developed. The method is based on continuous slow injection of a titrant into the calorimetric vessel. The experimental time for a cITC binding experiment is 12-20 min and the number of data points obtained is on the order of 1000. This gives an advantage over classical isothermal titration calorimetry (ITC) binding experiments that need 60-180 min to generate 20-30 data points. The method was validated using two types of calorimeters, which differ in calorimetric principle, geometry, stirring, and way of delivering the titrant into the calorimetric vessel. Two different experimental systems were used to validate the method: the binding of Ba(2+) to 18-crown-6 and the binding of cytidine 2'-monophosphate to RNAse A. Both systems are used as standard test systems for titration calorimetry. Computer simulations show that the dynamic range for determination of equilibrium constants can be increased by three orders of magnitude compared to that of classical ITC, making it possible to determine high affinities. Simulations also show an improved possibility to elucidate the actual binding model from cITC data. The simulated data demonstrate that cITC makes it easier to discriminate between different thermodynamic binding models due to the higher density of data points obtained from one experiment.

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

    Science.gov (United States)

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

    1990-01-01

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

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

    Science.gov (United States)

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

    2013-06-04

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

  9. Key considerations in the determination of polyelectrolyte concentration by the colloidal titration method

    Directory of Open Access Journals (Sweden)

    Miguel A. Zanuttini

    2007-01-01

    Full Text Available Medium or high charge density cationic polyelectrolytes are frequently used for water treatment. In the papermaking wet-end they are used as retention agents or as flocculating aids. Negative polyelectrolytes that enter the papermaking system increase the demand for cationic poly-electrolytes. Polyelectrolyte concentration can be determined by the colloidal titration method, using either of two options for detecting the endpoint: i visual observation or spectrophotometric determination of the colour change of an indicator, or ii streaming current measurement. This work discusses the best conditions for the application of the titration using spectrophotometric measurement for the end point detection. Poly-diallyldimethylammonium chloride was used as the cationic polyelec-trolyte, potassium polyvinyl sulphate as the negative polyelectrolyte, and o-toluidine blue as the positive indicator dye. The polyelectrolyte concen-tration range, interference from the metal ions affecting the indicator color change, the optimal indicator concentration to avoid precipitation problems, and the effect of adding a surfactant to the indicator solution were also considered. Titration curves were analyzed and optimized. Under these conditions the technique provided results with acceptable precision.

  10. Investigation by Mössbauer spectroscopy of Sn redox transformations during H2/O2 titration on Pt/Al2O3Sn-Cl and Pt/Al2O3SnIn-Cl naphtha reforming catalysts

    Science.gov (United States)

    Jahel, Ali; Avenier, Priscilla; Lacombe, Sylvie; Olivier-Fourcade, Josette; Jumas, Jean-Claude

    2010-03-01

    Bimetallic Pt/Al2O3Sn-Cl and trimetallic Pt/Al2O3SnIn-Cl catalysts were characterized by H2/O2 double titration and 119Sn Mössbauer spectroscopy. The addition of Sn or both Sn and In to the monometallic Pt/Al2O3-Cl catalyst leads to an increase in the volume of chemisorbed O2 at each titration. For bimetallic and trimetallic catalysts the increase in the Pt dispersion, calculated from the second oxygen titre, abnormally surpasses the barrier of 100%. Characterization of samples obtained after each step of the H2/O2 titration sequence using 119Sn Mössbauer spectroscopy allowed to follow the redox transformations of Sn species suspected of contributing to O2 consumption. 119Sn Mössbauer spectra show that after reduction unalloyed metalic Sn and PtSn alloy phases are formed in bi- and trimetallic catalysts respectively. These metallic phases are oxidized upon the first oxygen titre into the so-called PtxSn(O) oxometalic phases. The index calculated from this titre thus expresses the Pt-Sn bimetallic character and is called the bimetallicity index (BMI). These latter phases further undergo reduction and regeneration (oxidation) upon the second O2 titre and thus contribute to the calculated Pt dispersion as well.

  11. Ringbom titration curve equation of a strong base titrated multiple weak acid%一元强碱滴定多元弱酸溶液的林邦滴定曲线方程

    Institute of Scientific and Technical Information of China (English)

    乔成立; 马秀芳; 李文新

    2013-01-01

    In this paper, we used PBE、MBE、titration score and conditional stability constant to derive Ringbom titration curve equation of a strong base titration multiple weak acid based Ringbom theory, so as to resarch theoretical problem of acid-base titration laid the foundation.%以林邦理论为基础,用PBE、MBE、滴定分数和条件稳定常数等推导出一元强碱滴定多元弱酸溶液的林邦滴定曲线方程,为用酸碱滴定曲线方程解决酸碱滴定的理论问题,奠定了基础。

  12. 用离子浓度表示的氧化还原滴定的林邦滴定曲线方程%The redox titration of Ringbom titration curve equation is expressed by ion concentration

    Institute of Scientific and Technical Information of China (English)

    乔成立; 李文新

    2013-01-01

    Derived that ion concentration expressed reversible symmetrical complex redox titration and reversible asymmetric complex redox titration curve equation from redox the reaction equilibrium relationship and Ringbom adverse thought,so as to lay the foundation for solving the problem in the theory of the redox titration by redox titration curve equation.%用氧化还原反应平衡关系和林邦副反应思想推导出用离子浓度表示的可逆对称的复杂氧化还原滴定和可逆不对称的复杂氧化还原滴定的滴定曲线方程,为用氧化还原滴定曲线方程解决氧化还原滴定的理论问题奠定基础。

  13. Unraveling the thermodynamics and kinetics of RNA assembly: surface plasmon resonance, isothermal titration calorimetry, and circular dichroism.

    Science.gov (United States)

    Hoogstraten, Charles G; Sumita, Minako; White, Neil A

    2014-01-01

    The mechanisms and driving forces of the assembly of RNA tertiary structure are a topic of much current interest. In several systems, including our own work in the docking transition of the hairpin ribozyme, intramolecular RNA tertiary folding has been converted into an intermolecular binding event, allowing the full power of contemporary biophysical techniques to be brought to bear on the analysis. We review the use of three such methods: circular dichroism to isolate the binding of multivalent cations coupled to tertiary assembly, surface plasmon resonance to determine the rates of association and dissociation, and isothermal titration calorimetry to dissect the thermodynamic contributions to RNA assembly events. We pay particular attention to practical aspects of these studies, such as careful preparation of samples with fixed free concentrations of cations in order to avoid errors due to ion depletion effects that are common in RNA systems. Examples of applications from our own work with the hairpin ribozyme are shown. Distinctions among the data handling procedures for the various techniques used and solution conditions encountered are also discussed.

  14. Drug-binding energetics of human α-1-acid glycoprotein assessed by isothermal titration calorimetry and molecular docking simulations

    Science.gov (United States)

    Huang, Johnny X.; Cooper, Matthew A.; Baker, Mark A.; Azad, Mohammad A.K.; Nation, Roger L.; Li, Jian; Velkov, Tony

    2012-01-01

    This study utilizes sensitive, modern isothermal titration calorimetric (ITC) methods to characterize the microscopic thermodynamic parameters that drive the binding of basic drugs to α-1-acid glycoprotein (AGP) and thereby rationalize the thermodynamic data in relation to docking models and crystallographic structures of the drug-AGP complexes. The binding of basic compounds from the tricyclic antidepressant series, together with miaserine, chlorpromazine, disopyramide and cimetidine all displayed an exothermically driven binding interaction with AGP. The impact of protonation/deprotonation events, ionic strength, temperature and the individual selectivity of the A and F1*S AGP variants on drug-binding thermodynamics were characterized. A correlation plot of the thermodynamic parameters for all of the test compounds revealed enthalpy-entropy compensation is in effect. The exothermic binding energetics of the test compounds were driven by a combination of favorable (negative) enthalpic (ΔH°) and favorable (positive) entropic (ΔS°) contributions to the Gibbs free energy (ΔG°). Collectively, the data imply that the free energies that drive drug binding to AGP and its relationship to drug-serum residency evolve from the complex interplay of enthalpic and entropic forces from interactions with explicit combinations of hydrophobic and polar side-chain sub-domains within the multi-lobed AGP ligand binding cavity. PMID:23192962

  15. Isothermal titration calorimetric and computational studies on the binding of chitooligosaccharides to pumpkin (Cucurbita maxima) phloem exudate lectin.

    Science.gov (United States)

    Narahari, Akkaladevi; Singla, Hitesh; Nareddy, Pavan Kumar; Bulusu, Gopalakrishnan; Surolia, Avadhesha; Swamy, Musti J

    2011-04-14

    The interaction of chitooligosaccharides [(GlcNAc)(2-6)] with pumpkin phloem exudate lectin (PPL) was investigated by isothermal titration calorimetry and computational methods. The dimeric PPL binds to (GlcNAc)(3-5) with binding constants of 1.26-1.53 × 10(5) M(-1) at 25 °C, whereas chitobiose exhibits approximately 66-fold lower affinity. Interestingly, chitohexaose shows nearly 40-fold higher affinity than chitopentaose with a binding constant of 6.16 × 10(6) M(-1). The binding stoichiometry decreases with an increase in the oligosaccharide size from 2.26 for chitobiose to 1.08 for chitohexaose. The binding reaction was essentially enthalpy driven with negative entropic contribution, suggesting that hydrogen bonds and van der Waals' interactions are the main factors that stabilize PPL-saccharide association. The three-dimensional structure of PPL was predicted by homology modeling, and binding of chitooligosaccharides was investigated by molecular docking and molecular dynamics simulations, which showed that the protein binding pocket can accommodate up to three GlcNAc residues, whereas additional residues in chitotetraose and chitopentaose did not exhibit any interactions with the binding pocket. Docking studies with chitohexaose indicated that the two triose units of the molecule could interact with different protein binding sites, suggesting formation of higher order complexes by the higher oligomers of GlcNAc by their simultaneous interaction with two protein molecules.

  16. Development of High-purity Certified Reference Materials for 17 Proteinogenic Amino Acids by Traceable Titration Methods.

    Science.gov (United States)

    Kato, Megumi; Yamazaki, Taichi; Kato, Hisashi; Eyama, Sakae; Goto, Mari; Yoshioka, Mariko; Takatsu, Akiko

    2015-01-01

    To ensure the reliability of amino acid analyses, the National Metrology Institute of Japan of the National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) has developed high-purity certified reference materials (CRMs) for 17 proteinogenic amino acids. These CRMs are intended for use as primary reference materials to enable the traceable quantification of amino acids. The purity of the present CRMs was determined based on two traceable methods: nonaqueous acidimetric titration and nitrogen determination by the Kjeldahl method. Since neither method could distinguish compounds with similar structures, such as amino acid-related impurities, impurities were thoroughly quantified by combining several HPLC methods, and subtracted from the obtained purity of each method. The property value of each amino acid was calculated as a weighted mean of the corrected purities by the two methods. The uncertainty of the property value was obtained by combining measurement uncertainties of the two methods, a difference between the two methods, the uncertainty from the contribution of impurities, and the uncertainty derived from inhomogeneity. The uncertainty derived from instability was considered to be negligible based on stability monitoring of some CRMs. The certified value of each amino acid, property value with uncertainty, was given for both with or without enantiomeric separation.

  17. Sequence characteristics required for cooperative binding and efficient in vivo titration of the replication initiator protein DnaA in E. coli

    DEFF Research Database (Denmark)

    Hansen, Flemming G.; Christensen, Bjarke Bak; Atlung, Tove

    2007-01-01

    was eliminated by insertion of half a helical turn between any of the DnaA boxes. Titration strongly depends on the presence and orientation of the promoter distal R6 DnaA box located 104 bp upstream of the R5 box as well as neighbouring sequences downstream of R6. Titration depends on the integrity of a 43 bp...... was located less than 20 bp upstream of the -35 sequence. Thus, the architectural requirements for titration and for repression of transcription are different. A new set of rules for identifying efficiently titrating DnaA box regions was formulated and used to analyse sequences for which good titration data...

  18. Clinical predictors of central sleep apnea evoked by positive airway pressure titration

    Directory of Open Access Journals (Sweden)

    Moro M

    2016-07-01

    Full Text Available Marilyn Moro,1 Karen Gannon,1 Kathy Lovell,1 Margaret Merlino,1 James Mojica,2 Matt T Bianchi,1,3 1Neurology Department, 2Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, MA, USA; 3Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA Purpose: Treatment-emergent central sleep apnea (TECSA, also called complex apnea, occurs in 5%–15% of sleep apnea patients during positive airway pressure (PAP therapy, but the clinical predictors are not well understood. The goal of this study was to explore possible predictors in a clinical sleep laboratory cohort, which may highlight those at risk during clinical management.Methods: We retrospectively analyzed 728 patients who underwent PAP titration (n=422 split night; n=306 two-night. Demographics and self-reported medical comorbidities, medications, and behaviors as well as standard physiological parameters from the polysomnography (PSG data were analyzed. We used regression analysis to assess predictors of binary presence or absence of central apnea index (CAI ≥5 during split PSG (SN-PSG versus full-night PSG (FN-PSG titrations.Results: CAI ≥5 was present in 24.2% of SN-PSG and 11.4% of FN-PSG patients during titration. Male sex, maximum continuous positive airway pressure, and use of bilevel positive airway pressure were predictors of TECSA, and rapid eye movement dominance was a negative predictor, for both SN-PSG and FN-PSG patients. Self-reported narcotics were a positive predictor of TECSA, and the time spent in stage N2 sleep was a negative predictor only for SN-PSG patients. Self-reported history of stroke and the CAI during the diagnostic recording predicted TECSA only for FN-PSG patients.Conclusion: Clinical predictors of treatment-evoked central apnea spanned demographic, medical history, sleep physiology, and titration factors. Improved predictive models may be increasingly important as diagnostic and therapeutic modalities move away from the

  19. Titulador potenciométrico automatizado baseado em sistema de fluxo monossegmentado Automated potentiometric titrator based in monosegmented flow system

    Directory of Open Access Journals (Sweden)

    Edgard Moreira Ganzarolli

    1999-02-01

    Full Text Available A new automated system for acid-base flow titrations is proposed. In the operation mode, several sample to titrant volumetric ratios are injected in an air segmented plug. Five three way solenoid valves and three acrilic junctions, assembled in a hidrodynamic injection system, were accountable for the monosegmented reagents plug formation. A turbulent flow reactor was used for a perfect mix of reagents in the plug. The detector system employed a glass combined electrode fitted in an acrilic holder. Titrations of hydrochloric, nitric and acetic acids, in several concentrations, were performed with standard sodium hidroxide, for evaluation of the efficiency of the system. The relative standard deviation of the determinations was about ±0,5% and each titration was carried out in 3-4 minutes. A Quick BASIC 4.5® program was developed for the titrator control.

  20. Automatic photometric titration procedure based on multicommutation and flow-batch approaches employing a photometer based on twin LEDs

    OpenAIRE

    Silva,Milton B. da; Crispino,Carla C.; REIS, Boaventura F.

    2010-01-01

    In this work, a reliable and inexpensive photometer based on twin LEDs assembled as a radiation source and as a photodetector is described. The setup including the photometer and flow system module was designed to implement an automated titration procedure employing the multicommuted flow injection analysis (MCFIA) process. The proposed system was able to carry out photometric titration without using analytical curve to achieve the sample concentration. Its usefulness was proven by analyzing ...

  1. [Use of coulometric titration for elucidating the mechanism of the oxidation of 6-APA alkaline breakdown products by halogens].

    Science.gov (United States)

    Kharlamov, V T; Inkin, A A; Ermolina, G E

    1975-02-01

    Penaldinic acid and penicillamine were formed on alkali decomposition (1 N NaOH) of 6-APA for 20 minutes at room temperature, penicillamine being completely oxidized to disulphide by the air oxygen. Coulometric titration of the alkali decomposition products showed that generated chlorine in 0.5 N HCl solution or bromine in a week acid solution of KBr oxidized them with participation of 7 electrones. Generated iodine did not practically oxidize the 6-APA decomposition products during the coulometric titration.

  2. 估算有机物正常沸点的基团贡献法的研究进展%Research Progress of Group - contribution Methods for Estimating Normal Boiling Point of Organic Compounds

    Institute of Scientific and Technical Information of China (English)

    王小艳; 司继林

    2012-01-01

    Normal boiling points are one of the most important properties for organic compounds. Although there are many experimental values of the normal boiling point of organic compounds in the literature, but there are a few normal boiling point of the material cannot be obtained by experiment. We can obtain the normal boiling points by establishing the mathematical model, the group contribution method is the most important research methods to obtain the normal boiling point. A variety of group - contribution methods for estimating normal boiling point of organic compounds have been summarized. It has discussed the principles, advantages and disadvantages, application ranges of Joback method, C - G method, Xu - Wen method, position group contribution method, elements and bonds. The difference of these methods and the development trend of the methods for estimating normal boiling point of organic compounds was discussed.%有机物的正常沸点是重要的物性数据之一。尽管文献中有很多化合物正常沸点的实验值,但一些物质的正常沸点不能由实验获得,可以通过建立数学模型来估算缺少的有机物正常沸点,其中基团贡献法是人们获得正常沸点的最重要研究方法。本文对估算有机物正常沸点的基团贡献法进行了综述。主要介绍了Joback法、C—G法、许文法、定位分布贡献法、元素和化学键法等方法的原理、优缺点及应用范围;并对这些方法进行简单的比较;最后指出了有机物正常沸点的基团贡献法的发展趋势。

  3. 对酸碱滴定反应的思考与拓展%The Thinking and Expand of Acid-base Titration Reaction

    Institute of Scientific and Technical Information of China (English)

    樊滢玮

    2015-01-01

    In this paper, through the summary and thinking of acid-base titration reaction, further expand to the double indicator titration, redox titration, complexometric titration and precipitation titratio, analyzed the common titration analysis experiment in chemical experiment teaching, we hope this could be helpful for people to further understand the principle of the titration experiments and master the four titration reaction.%文章通过对酸碱滴定反应的总结与思考,进一步拓展到双指示剂滴定、氧化还原滴定、配位滴定和沉淀滴定法,对化学实验教学中常见的滴定分析实验进行了解析,希望对大家进一步理解滴定实验原理,掌握四大滴定有所帮助。

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

    Science.gov (United States)

    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

  5. Artificial Neural Network-Group Contribution Method for Predicting Standard Enthalpy of Formation in the Solid State: C-H, C-H-O, C-H-N, and C-H-N-O Compounds

    Science.gov (United States)

    Guella, Soufiane; Argoub, Kadda; Benkouider, Ali Mustapha; Yahiaoui, Ahmed; Kessas, Rachid; Bagui, Farid

    2015-11-01

    In this work, an artificial neural network-group contribution model is developed to predict the standard enthalpy of formation in the solid (crystal) state of pure compounds. Several classes of hydrocarbon compounds CH, oxygenated compounds CHO, nitrogen compounds CHN, and energetic compounds CHNO are investigated to propose a comprehensive and predictive model. The new model is developed and tested for 1222 organic compounds containing complex molecular structures. The performance of the new model has been compared with previous work and is shown to be far more accurate. The obtained results show an average absolute deviation of 9.33 {kJ}{\\cdot }{mol}^{-1} and a coefficient of determination of 0.9972 for the experimental values.

  6. Isolating Age-Group Differences in Working Memory Load-Related Neural Activity: Assessing the Contribution of Working Memory Capacity Using a Partial-Trial fMRI Method

    Science.gov (United States)

    Bennett, Ilana J.; Rivera, Hannah G.; Rypma, Bart

    2013-01-01

    Previous studies examining age-group differences in working memory load-related neural activity have yielded mixed results. When present, age-group differences in working memory capacity are frequently proposed to underlie these neural effects. However, direct relationships between working memory capacity and working memory load-related activity have only been observed in younger adults. These relationships remain untested in healthy aging. Therefore, the present study examined patterns of working memory load-related activity in 22 younger and 20 older adults and assessed the contribution of working memory capacity to these load-related effects. Participants performed a partial-trial delayed response item recognition task during functional magnetic resonance imaging. In this task, participants encoded either 2 or 6 letters, maintained them during a delay, and then indicated whether a probe was present in the memory set. Behavioral results revealed faster and more accurate responses to load 2 versus 6, with age-group differences in this load condition effect for the accuracy measure. Neuroimaging results revealed one region (medial superior frontal gyrus) that showed age-group differences in load-related activity during the retrieval period, with less (greater) neural activity for the low versus high load condition in younger (older) adults. Furthermore, for older adults, load-related activity did not vary as a function of working memory capacity. Thus, working memory-related activity varies with healthy aging, but these patterns are not due solely to working memory capacity. Neurocognitive aging theories that feature capacity will need to account for these results. PMID:23357076

  7. Contributions of separate reactions to the acid-base buffering of soils in brook floodplains (Central Forest State Reserve)

    Science.gov (United States)

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

    2016-04-01

    The acid-base buffering of gleyic gray-humus soils developed in brook floodplains and undisturbed southern-taiga landscapes has been characterized by the continuous potentiometric titration of soil water suspensions. During the interaction with an acid, the major amount of protons (>80%) is consumed for the displacement of exchangeable bases and the dissolution of Ca oxalates. In the O and AY horizons, Mn compounds make the major contribution (2-15%) to the acid buffering. The buffer reactions with the participation of Al compounds make up from 0.5 to 1-2% of the total buffering capacity, and the protonation of the surface OH groups of kaolinite consumes 2-3% of the total buffering capacity. The deprotonation of OH groups on the surface of Fe hydroxides (9-43%), the deprotonation of OH groups on the surface of illite crystals (3-19%), and the dissolution of unidentified aluminosilicates (9-14%) are the most significant buffer reactions whose contributions have been quantified during the interaction with a base. The contribution of the deprotonation of OH groups on the surface of kaolinite particles is lower (1-5%) because of the small specific surface area of this mineral, and that of the dissolution of Fe compounds is insignificant. In the AY horizon, the acid and base buffering of soil in the rhizosphere is higher than beyond the rhizosphere because of the higher contents of organic matter and nonsilicate Fe and Al compounds.

  8. Isothermal titration calorimetry study of the interaction of sweeteners with fullerenols as an artificial sweet taste receptor model.

    Science.gov (United States)

    Chen, Zhong-Xiu; Guo, Gang-Min; Deng, Shao-Ping

    2009-04-08

    A fullerenol-based synthetic sweetness receptor model, consisting of polyhydroxy groups for potential hydrogen bond donor along with a spherical hydrophobic center, was proposed according to the widely accepted sweetness hypothesis. An isothermal titration calorimetry (ITC) technique was used to study mimetic interaction of this sweet receptor model with a series of sweeteners having increasing sweetness intensity. The results showed that ITC is an effective method to provide thorough and precise characterization of the energies of molecular complex formation. Binding of all of the studied sweeteners with fullerenols was found through two sets of site models. More heat was released from sweeter synthetic compounds binding with fullerenols than from less sweet carbohydrates. The results imply that hydrogen bond formation is necessary for the sweeteners to bind to the fullerenol receptor in the first stage, whereas hydrophobic effect and conformation changes that lead to favorable entropy changes occur in most cases. The preliminary results of this study help to cover the lack of information about the thermodynamic basis of understanding of the initiation of the sweet sensation. It also adds complementary physicochemical measurements available for comparison with the sweetness hypothesis. On the other hand, a correlation between the thermodynamic parameters and sweetness intensity has been made as well, which exhibits potential as a useful tool in sensory analysis.

  9. Microcalorimetric and potentiometric titration studies on the adsorption of copper by P. putida and B. thuringiensis and their composites with minerals

    Energy Technology Data Exchange (ETDEWEB)

    Fang Linchuan [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Key Laboratory of Subtropical Agriculture and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Cai Peng; Li Pengxiang; Wu Huayong; Liang Wei; Rong Xingmin [Key Laboratory of Subtropical Agriculture and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Chen Wenli [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Huang Qiaoyun, E-mail: qyhuang@mail.hzau.edu.cn [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Key Laboratory of Subtropical Agriculture and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China)

    2010-09-15

    In order to have a better understanding of the interactions of heavy metals with bacteria and minerals in soil and associated environments, isothermal titration calorimetry (ITC), potentiometric titration and equilibrium sorption experiments were conducted to investigate the adsorption behavior of Cu(II) by Bacillus thuringiensis, Pseudomonas putida and their composites with minerals. The interaction of montmorillonite with bacteria increased the reactive sites and resulted in greater adsorption for Cu(II) on their composites, while decreased adsorption sites and capacities for Cu(II) were observed on goethite-bacteria composites. A gram-positive bacterium B. thuringiensis played a more important role than a gram-negative bacterium P. putida in determining the properties of the bacteria-minerals interfaces. The enthalpy changes ({Delta}H{sub ads}) from endothermic (6.14 kJ mol{sup -1}) to slightly exothermic (-0.78 kJ mol{sup -1}) suggested that Cu(II) is complexed with the anionic oxygen ligands on the surface of bacteria-mineral composites. Large entropies (32.96-58.89 J mol{sup -1} K{sup -1}) of Cu(II) adsorption onto bacteria-mineral composites demonstrated the formation of inner-sphere complexes in the presence of bacteria. The thermodynamic data implied that Cu(II) mainly bound to the carboxyl and phosphoryl groups as inner-sphere complexes on bacteria and mineral-bacteria composites.

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

    Science.gov (United States)

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

    1986-06-01

    Homogeneous sets of data from strong acid-strong base potentiometric titrations in aqueous solution at various constant ionic strengths have been analysed by statistical criteria. The aim is to see whether the error distribution matches that for the equilibrium constants determined by competitive potentiometric methods using the glass electrode. The titration curve can be defined when the estimated equivalence volume VEM, with standard deviation (s.d.) sigma (VEM), the standard potential E(0), with s.d. sigma(E(0)), and the operational ionic product of water K(*)(w) (or E(*)(w) in mV), with s.d. sigma(K(*)(w)) [or sigma(E(*)(w))] are known. A special computer program, BEATRIX, has been written which optimizes the values of VEM, E(0) and K(*)(w) by linearization of the titration curve as a Gran plot. Analysis of variance applied to a set of 11 titrations in 1.0M sodium chloride medium at 298 K has demonstrated that the values of VEM belong to a normal population of points corresponding to individual potential/volume data-pairs (E(i); v(i)) of any titration, whereas the values of pK(*)(w) (or of E(*)(w)) belong to a normal population with members corresponding to individual titrations, which is also the case for the equilibrium constants. The intertitration variation is attributable to the electrochemical component of the system and appears as signal noise distributed over the titrations. The correction for junction-potentials, introduced in a further stage of the program by optimization in a Nernst equation, increases the noise, i.e., sigma(pK(*)(w)). This correction should therefore be avoided whenever it causes an increase of sigma(pK(*)(w)). The influence of the ionic medium has been examined by processing data from acid-base titrations in 0.1M potassium chloride and 0.5M potassium nitrate media. The titrations in potassium chloride medium showed the same behaviour as those in sodium chloride medium, but with an s.d. for pK(*)(w) that was smaller and close to the

  11. Effects of fixed or self-titrated dosages of Sativex on cannabis withdrawal and cravings.

    Science.gov (United States)

    Trigo, Jose M; Lagzdins, Dina; Rehm, Jürgen; Selby, Peter; Gamaleddin, Islam; Fischer, Benedikt; Barnes, Allan J; Huestis, Marilyn A; Le Foll, Bernard

    2016-04-01

    There is currently no pharmacological treatment approved for cannabis dependence. In this proof of concept study, we assessed the feasibility/effects of fixed and self-titrated dosages of Sativex (1:1, Δ(9)-tetrahydrocannabinol (THC)/cannabidiol (CBD)) on craving and withdrawal from cannabis among nine community-recruited cannabis-dependent subjects. Participants underwent an 8-week double-blind placebo-controlled trial (an ABACADAE design), with four smoke as usual conditions (SAU) (A) separated by four cannabis abstinence conditions (B-E), with administration of either self-titrated/fixed doses of placebo or Sativex (up to 108 mg THC/100 mg CBD). The order of medication administration during abstinence conditions was randomized and counterbalanced. Withdrawal symptoms and craving were assessed using the Cannabis Withdrawal Scale (CWS), Marijuana Withdrawal Checklist (MWC) and Marijuana Craving Questionnaire (MCQ). Medication use was assessed during the study by means of self-reports, vial weight control, toxicology and metabolite analysis. Cannabis use was assessed by means of self-reports. High fixed doses of Sativex were well tolerated and significantly reduced cannabis withdrawal during abstinence, but not craving, as compared to placebo. Self-titrated doses were lower and showed limited efficacy as compared to high fixed doses. Participants reported a significantly lower "high" following Sativex or placebo as compared to SAU conditions. Cannabis/medication use along the study, as per self-reports, suggests compliance with the study conditions. The results found in this proof of concept study warrant further systematic exploration of Sativex as a treatment option for cannabis withdrawal and dependence. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. Paleoproterozoic source contributions to the São Roque Group sedimentation: LA-MC-ICPMS U-Pb dating and Sm-Nd systematics of clasts from metaconglomerates of the Boturuna Formation

    Directory of Open Access Journals (Sweden)

    Larry Michael Heaman

    2012-12-01

    Full Text Available The So Roque Group is characterized by volcano-sedimentary sequences, in which deposition probably started in the late Paleoproterozoic. U-Pb dating by LA-MC-ICPMS of zircons extracted from predominantly equigranular monzogranites clasts from Morro Doce and Morro do Polvilho regions, yield paleoproterozoic ages of 2199 8.5 Ma and 2247 13 Ma, respectively. These represent the ages for the main source of granite for the metaconglomerates from the Boturuna Formation (basal unit of So Roque Group. Its polycyclic history is reinforced by the presence of inherited Archean zircons (2694 29 Ma found within the clasts. Moreover, these clasts have also been affected by the Neoproterozoic overprinting event as indicated by their lower intercept Concordia ages. Sm-Nd isotope data for the main clast varieties from the Morro Doce metaconglomerates yield TDM ages of 2.6 to 2.7 Ga, demonstrating that these granites are the recycling products of an Archean crustal component. The metaconglomerate arkosean framework yields slightly lower ENd(t values than those for the clasts, indicating that a younger and/or more primitive source also contributed to the Boturuna Formation.

  13. Paleoproterozoic source contributions to the Sao Roque Group sedimentation: LA-MC-ICPMS U-Pb dating and Sm-Nd systematics of clasts from metaconglomerates of the Boturuna Formation

    Energy Technology Data Exchange (ETDEWEB)

    Henrique-Pinto, Renato; Janasi, Valdecir de Assis; Tassinari, Colombo Celso Gaeta [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotectonica; Simonetti, Antonio [University of Notre Dame, South Bend (United States). Dept. of Civil Engineering and Geological Sciences; Heaman, Larry Michael, E-mail: renatohp@usp.br, E-mail: vajanasi@usp.br, E-mail: ccgtassi@usp.br, E-mail: antonio.simonetti.3@nd.edu, E-mail: larry.heaman@ualberta.ca [University of Alberta, Edmonton (Canada). Dept. of Earth and Atmospheric Sciences

    2012-12-15

    The Sao Roque Group is characterized by volcano-sedimentary sequences, in which deposition probably started in the late Paleoproterozoic. U-Pb dating by LA-MC-ICPMS of zircons extracted from predominantly equigranular monzogranites clasts from Morro Doce and Morro do Polvilho regions, yield paleoproterozoic ages of 2199 {+-}8.5 Ma and 2247 {+-}13 Ma, respectively. These represent the ages for the main source of granite for the metaconglomerates from the Boturuna Formation (basal unit of Sao Roque Group). Its polycyclic history is reinforced by the presence of inherited Archean zircons (2694 {+-}29 Ma) found within the clasts. Moreover, these clasts have also been affected by the Neoproterozoic overprinting event as indicated by their lower intercept Concordia ages. Sm-Nd isotope data for the main clast varieties from the Morro Doce metaconglomerates yield T{sub DM} ages of 2.6 to 2.7 Ga, demonstrating that these granites are the recycling products of an Archean crustal component. The metaconglomerate arkosean framework yields slightly lower {epsilon}{sub Nd(t)} values than those for the clasts, indicating that a younger and/or more primitive source also contributed to the Boturuna Formation. (author)

  14. Automated high-pressure titration system with in situ infrared spectroscopic detection

    Science.gov (United States)

    Thompson, Christopher J.; Martin, Paul F.; Chen, Jeffrey; Benezeth, Pascale; Schaef, Herbert T.; Rosso, Kevin M.; Felmy, Andrew R.; Loring, John S.

    2014-04-01

    A fully automated titration system with infrared detection was developed for investigating interfacial chemistry at high pressures. The apparatus consists of a high-pressure fluid generation and delivery system coupled to a high-pressure cell with infrared optics. A manifold of electronically actuated valves is used to direct pressurized fluids into the cell. Precise reagent additions to the pressurized cell are made with calibrated tubing loops that are filled with reagent and placed in-line with the cell and a syringe pump. The cell's infrared optics facilitate both transmission and attenuated total reflection (ATR) measurements to monitor bulk-fluid composition and solid-surface phenomena such as adsorption, desorption, complexation, dissolution, and precipitation. Switching between the two measurement modes is accomplished with moveable mirrors that direct the light path of a Fourier transform infrared spectrometer into the cell along transmission or ATR light paths. The versatility of the high-pressure IR titration system was demonstrated with three case studies. First, we titrated water into supercritical CO2 (scCO2) to generate an infrared calibration curve and determine the solubility of water in CO2 at 50 °C and 90 bar. Next, we characterized the partitioning of water between a montmorillonite clay and scCO2 at 50 °C and 90 bar. Transmission-mode spectra were used to quantify changes in the clay's sorbed water concentration as a function of scCO2 hydration, and ATR measurements provided insights into competitive residency of water and CO2 on the clay surface and in the interlayer. Finally, we demonstrated how time-dependent studies can be conducted with the system by monitoring the carbonation reaction of forsterite (Mg2SiO4) in water-bearing scCO2 at 50 °C and 90 bar. Immediately after water dissolved in the scCO2, a thin film of adsorbed water formed on the mineral surface, and the film thickness increased with time as the forsterite began to dissolve

  15. Thermodynamics of actinide complexation in solution at elevated temperatures: application of variable-temperature titration calorimetry.

    Science.gov (United States)

    Rao, Linfeng

    2007-06-01

    Studies of actinide complexation in solution at elevated temperatures provide insight into the effect of solvation and the energetics of complexation, and help to predict the chemical behavior of actinides in nuclear waste processing and disposal where temperatures are high. This tutorial review summarizes the data on the complexation of actinides at elevated temperatures and describes the methodology for thermodynamic measurements, with the emphasis on variable-temperature titration calorimetry, a highly valuable technique to determine the enthalpy and, under appropriate conditions, the equilibrium constants of complexation as well.

  16. Determination of Sulfides in FCC Gasoline by Using the Potentiometric Titration of Lead Tetraacetate

    Institute of Scientific and Technical Information of China (English)

    罗立文; 夏道宏

    2004-01-01

    Compared with conventional method of violet spectrum, determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages such as clear potentiometric abrupt change at the stoichiometric point, stable potentiometric value, exact and credible results, and simple operation. The content of sulfides in FCC gasoline of Shenghua refinery is 0.136% by this method. The standard deviation about this method is less than 0.01% and the relative standard deviation is less than 2.42%.

  17. Automated High-Pressure Titration System with In Situ Infrared Spectroscopic Detection

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Christopher J.; Martin, Paul F.; Chen, Jeffrey; Benezeth, Pascale; Schaef, Herbert T.; Rosso, Kevin M.; Felmy, Andrew R.; Loring, John S.

    2014-04-17

    A fully automated titration system with infrared detection was developed for investigating interfacial chemistry at high pressures. The apparatus consists of a high-pressure fluid generation and delivery system coupled to a high-pressure cell with infrared optics. A manifold of electronically actuated valves is used to direct pressurized fluids into the cell. Precise reagent additions to the pressurized cell are made with calibrated tubing loops that are filled with reagent and placed in-line with the cell and a syringe pump. The cell’s infrared optics facilitate both transmission and attenuated total reflection (ATR) measurements to monitor bulk-fluid composition and solid-surface phenomena such as adsorption, desorption, complexation, dissolution, and precipitation. Switching between the two measurement modes is accomplished with moveable mirrors that direct radiation from a Fourier transform infrared spectrometer into the cell along transmission or ATR light paths. The versatility of the high-pressure IR titration system is demonstrated with three case studies. First, we titrated water into supercritical CO2 (scCO2) to generate an infrared calibration curve and determine the solubility of water in CO2 at 50 °C and 90 bar. Next, we characterized the partitioning of water between a montmorillonite clay and scCO2 at 50 °C and 90 bar. Transmission-mode spectra were used to quantify changes in the clay’s sorbed water concentration as a function of scCO2 hydration, and ATR measurements provided insights into competitive residency of water and CO2 on the clay surface and in the interlayer. Finally, we demonstrated how time-dependent studies can be conducted with the system by monitoring the carbonation reaction of forsterite (Mg2SiO4) in water-bearing scCO2 at 50 °C and 90 bar. Immediately after water dissolved in the scCO2, a thin film of adsorbed water formed on the mineral surface, and the film thickness increased with time as the forsterite began to dissolve

  18. Modeling of Complexometric Titration Data: Applications and Implications of New Computational Tools and Thermodynamic Data

    Science.gov (United States)

    Hudson, R.; Omanovic, D.; Kogut, M.; Voelker, B. M.

    2016-02-01

    Complexometric titration of natural ligands in seawater using the competitive ligand equilibration-adsorptive cathodic stripping voltammetry method (CLE-AdCSV) is the method of choice for characterizing the organic complexation of Cu and Fe in seawater. Interpreting such titration data is made difficult by the complexity of the modeling process, which arises from the need to estimate non-linear model equations, the potential for artifacts, and the use of reference equilibrium constants that have been subject of only limited study. Due to the need to model multi-component equilibrium systems when these titration data, a variety of approximations have been made in order to allow standard linear and non-linear regression tools to be applied. Two software tools, KINETEQL and ProMCC, solve the model equations exactly and allow users to estimate complexation model parameters accurately. ProMCC excels in visualization and ease-of-use, while KINETEQL provides the user with flexibility in the definition of equilibrium models and has the additional capability of solving reaction kinetics problems. A detailed example of the application of KINETQL to simulating the kinetics of Cu(II) complexation by EDTA in seawater will be illustrated. The implications of kinetics for experimental determination of the stability constants of natural Cu- and Fe-binding ligands will be addressed. These modeling tools make it feasible to design experiments and analyze datasets using new, complex approaches to data analysis, i.e., data from multiple CLE-AdCSV titrations obtained in different analytical windows. This approach can help solve to the problem of internal calibration in waters that contain mixtures of weak and strong ligands. Because it attempts to model data that span a much wider range in chemistries, the "multiwindow" approach is especially vulnerable to bias in the reference complex stability constants. The difficulty of obtaining coherent models of multiwindow CLE-AdCSV datasets

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Titrimetric determination of volatile fatty acids (VFAs) contents is a common way to monitor a biogas process. However, digested manure from co-digestion biogas plants has a complex matrix with high concentrations of interfering components, resulting in varying results when using different...... (GC) analysis. Two of the procedures are commonly used in biogas plants and two are discussed in literature. The results showed that the optimal titration results were obtained when 40mL of four times diluted digested manure was gently stirred (200rpm). Results from samples with different VFA...

  20. Determination of Formation Constants of Co2+,Ni2+,Cu2+and Zn2+ Complexes with Humic and Fulvic Acids by Potentionmetric Titration Method

    Institute of Scientific and Technical Information of China (English)

    DUJIN-ZHOU; LUCHANG-QING; 等

    1994-01-01

    The formation constants of Co2+,Ni2+,Cu2+ and Zn2+ complexes with humic acid(HA) and fulvic acid(FA) in red soil wrer determined by the potentiometric titration method.The constants as a function of composition of the complexation solutions were obtained by two graphical approaches respetively,The formation constants decreased with increasing concentration of metal in the solution,The results provide unambiguous evidence for the heterogeneity of the function groups of humic substances,the formation constants of FA were much smaller than those of HA,and the formation constants of Cu2+ were much greater than those of Co2+ ,Ni2+ and Zn2+,The potentiometric titration methon for determining formation constants are also discussed in the article.

  1. An equilibrium model for ligand-modified micellar-enhanced ultrafiltration. Selective separation of metal ions using iminoacetic substituted polyamines and a theoretical model for the titration behavior of polyamines

    Energy Technology Data Exchange (ETDEWEB)

    Dharmawardana, Udeni Rajaratna [Univ. of Oklahoma, Norman, OK (United States)

    1992-01-01

    This thesis consists of three chapters. Chapter 1, An equilibrium model for ligand-modified micellar-enhanced ultrafiltration, describes a theoretical model and experimental investigations which used the semi-equilibrium-dialysis method with N-n-dodecyl iminodiacetic acid as the ligand. In Chapter 2, Selective separation of metal ions using iminoacetic substituted polyamines, polyamines with a substituted ligand group are synthesized and used in investigating selective separation of copper ions from aqueous solution. In Chapter 3, A theoretical model for the titration behavior of polyamines, a novel approach to explain the titration behavior of polymeric amines based on the binding behavior of counterions is described. The application of this study is to the investigation of inexpensive and efficient methods of industrial waste water treatment.

  2. "The contribution of chronic diseases to the prevalence of dependence among older people in Latin America, China and India: a 10/66 Dementia Research Group population-based survey"

    Directory of Open Access Journals (Sweden)

    Salas Aquiles

    2010-08-01

    Full Text Available Abstract Background The number of older people is set to increase dramatically worldwide. Demographic changes are likely to result in the rise of age-related chronic diseases which largely contribute to years lived with a disability and future dependence. However dependence is much less studied although intrinsically linked to disability. We investigated the prevalence and correlates of dependence among older people from middle income countries. Methods A one-phase cross-sectional survey was carried out at 11 sites in seven countries (urban sites in Cuba, Venezuela, and Dominican Republic, urban and rural sites in Peru, Mexico, China and India. All those aged 65 years and over living in geographically defined catchment areas were eligible. In all, 15,022 interviews were completed with an informant interview for each participant. The full 10/66 Dementia Research Group survey protocol was applied, including ascertainment of depression, dementia, physical impairments and self-reported diagnoses. Dependence was interviewer-rated based on a key informant's responses to a set of open-ended questions on the participant's needs for care. We estimated the prevalence of dependence and the independent contribution of underlying health conditions. Site-specific prevalence ratios were meta-analysed, and population attributable prevalence fractions (PAPF calculated. Results The prevalence of dependence increased with age at all sites, with a tendency for the prevalence to be lower in men than in women. Age-standardised prevalence was lower in all sites than in the USA. Other than in rural China, dementia made the largest independent contribution to dependence, with a median PAPF of 34% (range 23%-59%. Other substantial contributors were limb impairment (9%, 1%-46%, stroke (8%, 2%-17%, and depression (8%, 1%-27%. Conclusion The demographic and health transitions will lead to large and rapid increases in the numbers of dependent older people particularly in

  3. High-precision, high-throughput stability determinations facilitated by robotics and a semiautomated titrating fluorometer.

    Science.gov (United States)

    Edgell, Marshall Hall; Sims, Dorothy A; Pielak, Gary J; Yi, Fang

    2003-06-24

    The use of statistical modeling to test hypotheses concerning the determinants of protein structure requires stability data (e.g., the free energy of denaturation in H(2)O, DeltaG(HOH)) from hundreds of protein mutants. Fluorescence-monitored chemical denaturation provides a convenient method for high-precision, high-throughput DeltaG(HOH) determination. For eglin c we find that a throughput of about 20 min per protein can be attained in a two-channel semiautomated titrating fluorometer. We find also that the use of robotics for protein purification and preparation of the solutions for chemical denaturation gives highly precise DeltaG(HOH) values in which the standard deviation of values from multiple preparations (+/-0.051 kcal/mol) differs very little from multiple measurements from a single preparation (+/-0.040 kcal/mol). Since the variance introduced into model fitting by DeltaG(HOH) increases as the square of measurement error, there is a premium on precision. In fact, the fraction of stability behavior explicable by otherwise perfect models goes from 98% to only 50% over the error range commonly reported for chemical denaturation measurements (0.1-0.6 kcal/mol). We have found that the precision of chemical denaturation DeltaG(HOH) measurements depends most heavily on the precision of the instrument used, followed by protein purity and the capacity to precisely prepare the solutions used for titrations.

  4. Determination of surface charge density of α-alumina by acid-base titration

    Directory of Open Access Journals (Sweden)

    Justin W. Ntalikwa

    2007-04-01

    Full Text Available The surface charge density (σo of colloidal alpha alumina suspended in various 1:1 electrolytes was measured using acid-base titration. An autotitrator capable of dispensing accurately 25 plus or minus 0.1 μL of titrant was used. The pH and temperature in the titration cell were monitored using single junction electrodes and platinum resistance thermometers, respectively. A constant supply of nitrogen gas in the cell was used to maintain inert conditions. The whole set up was interfaced with a computer for easy data acquisition. It was observed that the material exhibits a point of zero charge (PZC, this occurred at pH of 7.8 plus or minus 0.1, 7.6 plus or minus 0.2, 8.5 plus or minus 0.1, 8.3 plus or minus 0.1 for NaCl, NaNO3, CsCl and CsNO3 systems, respectively. It was also observed that below PZC, σo increases with increase in electrolyte concentration (Co whereas above PZC, σo decreases with increase in Co. It was concluded that σo of this material is a function of pH and Co and that its polarity can be varied through zero by varying these parameters.

  5. Microtubule-associated proteins and tubulin interaction by isothermal titration calorimetry.

    Science.gov (United States)

    Tsvetkov, P O; Barbier, P; Breuzard, G; Peyrot, V; Devred, F

    2013-01-01

    Microtubules play an important role in a number of vital cell processes such as cell division, intracellular transport, and cell architecture. The highly dynamic structure of microtubules is tightly regulated by a number of stabilizing and destabilizing microtubule-associated proteins (MAPs), such as tau and stathmin. Because of their importance, tubulin-MAPs interactions have been extensively studied using various methods that provide researchers with complementary but sometimes contradictory thermodynamic data. Isothermal titration calorimetry (ITC) is the only direct thermodynamic method that enables a full thermodynamic characterization (stoichiometry, enthalpy, entropy of binding, and association constant) of the interaction after a single titration experiment. This method has been recently applied to study tubulin-MAPs interactions in order to bring new insights into molecular mechanisms of tubulin regulation. In this chapter, we review the technical specificity of this method and then focus on the use of ITC in the investigation of tubulin-MAPs binding. We describe technical issues which could arise during planning and carrying out the ITC experiments, in particular with fragile proteins such as tubulin. Using examples of stathmin and tau, we demonstrate how ITC can be used to gain major insights into tubulin-MAP interaction. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Chelate titrations of Ca(2+) and Mg(2+) using microfluidic paper-based analytical devices.

    Science.gov (United States)

    Karita, Shingo; Kaneta, Takashi

    2016-06-14

    We developed microfluidic paper-based analytical devices (μPADs) for the chelate titrations of Ca(2+) and Mg(2+) in natural water. The μPAD consisted of ten reaction zones and ten detection zones connected through narrow channels to a sample zone located at the center. Buffer solutions with a pH of 10 or 13 were applied to all surfaces of the channels and zones. Different amounts of ethylenediaminetetraacetic acid (EDTA) were added to the reaction zones and a consistent amount of a metal indicator (Eriochrome Black T or Calcon) was added to the detection zones. The total concentrations of Ca(2+) and Mg(2+) (total hardness) in the water were measured using a μPAD containing a buffer solution with a pH of 10, whereas only Ca(2+) was titrated using a μPAD prepared with a potassium hydroxide solution with a pH of 13. The μPADs permitted the determination of Ca(2+) and Mg(2+) in mineral water, river water, and seawater samples within only a few minutes using only the naked eye-no need of instruments.

  7. Dopant titrating ion mobility spectrometry for trace exhaled nitric oxide detection.

    Science.gov (United States)

    Peng, Liying; Hua, Lei; Li, Enyou; Wang, Weiguo; Zhou, Qinghua; Wang, Xin; Wang, Changsong; Li, Jinghua; Li, Haiyang

    2015-01-05

    Ion mobility spectrometry (IMS) is a promising non-invasive tool for the analysis of exhaled gas and exhaled nitric oxide (NO), a biomarker for diagnosis of respiratory diseases. However, the high moisture in exhaled gas always brings about extra overlapping ion peaks and results in poor identification ability. In this paper, p-benzoquinone (PBQ) was introduced into IMS to eliminate the interference of overlapping ion peaks and realize the selective identification of NO. The overlapping ions caused by moisture were titrated by PBQ and then converted to hydrated PBQ anions (C6H4[Formula: see text](H2O)n). The NO concentration could be determined by quantifying gas phase hydrated nitrite anions (N[Formula: see text](H2O)n), product ions of NO. Under optimized conditions, a limit of detection (LOD) of about 1.4 ppbv and a linear range of 10-200 ppbv were obtained for NO even in 100% relative humidity (RH) purified air. Furthermore, this established method was applied to measure hourly the exhaled NO of eight healthy volunteers, and real-time monitoring the exhaled NO of an esophageal carcinoma patient during radical surgery. These results revealed the potential of the current dopant titrating IMS method in the measurement of exhaled NO for medical disease diagnosis.

  8. Isoelectric focusing and titration curves in biomedicine and in agrofood industries: a multimedia teaching program.

    Science.gov (United States)

    Cade-Treyer, D; Cade, A; Darjo, A; Jouvion-Moreno, M

    1996-03-01

    The aim of this 45 min, 60 megabyte, modular program is to initiate students, scientists and engineers of biotechnology, biomedicine and agrofood industries into isoelectric focusing (IEF) and titration curves for analytical (e.g. IEF, zone electrophoresis, isotachophoresis, electrotransfer) and preparative (e.g. ion-exchange chromatography, chromatofocusing) application of charge-dependent methods. For advanced teaching, the following theoretical and practical aspects may be of interest: pH gradient engineering, IEF resolving power, generation of pH gradient, sample-ampholyte interactions, pH gradient drift, immobilized pH gradients (IPG), IPG-two-dimensional (2-D) electrophoresis, preparative methods with multi-compartments and IPG membranes, capillary IEF, isozyme analysis, etc.). The program associates fixed and animated drawings, and computer-assisted simulations, with spoken and written commentaries (in English). It is illustrated with numerous IEF gel patterns and titration curves and some video sequences to be run on a multimedia PC with MS Windows 3.1 (or later releases) as the only software. The linear presentation of the program may be used directly on the PC, or may be projected on a screen from the PC, for small classes or for a larger audience (200 persons). Its development as an interactive multimedia program is in progress and will soon be available on the Internet.

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

    Science.gov (United States)

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

    2014-07-01

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

  10. A minimal titration model of the mammalian dynamical heat shock response

    Science.gov (United States)

    Sivéry, Aude; Courtade, Emmanuel; Thommen, Quentin

    2016-12-01

    Environmental stress, such as oxidative or heat stress, induces the activation of the heat shock response (HSR) and leads to an increase in the heat shock proteins (HSPs) level. These HSPs act as molecular chaperones to maintain cellular proteostasis. Controlled by highly intricate regulatory mechanisms, having stress-induced activation and feedback regulations with multiple partners, the HSR is still incompletely understood. In this context, we propose a minimal molecular model for the gene regulatory network of the HSR that reproduces quantitatively different heat shock experiments both on heat shock factor 1 (HSF1) and HSPs activities. This model, which is based on chemical kinetics laws, is kept with a low dimensionality without altering the biological interpretation of the model dynamics. This simplistic model highlights the titration of HSF1 by chaperones as the guiding line of the network. Moreover, by a steady states analysis of the network, three different temperature stress regimes appear: normal, acute, and chronic, where normal stress corresponds to pseudo thermal adaption. The protein triage that governs the fate of damaged proteins or the different stress regimes are consequences of the titration mechanism. The simplicity of the present model is of interest in order to study detailed modelling of cross regulation between the HSR and other major genetic networks like the cell cycle or the circadian clock.

  11. 正常人不同年龄组平衡功能之间的比较%Comparing the contributions to postural control among different age groups of healthy population

    Institute of Scientific and Technical Information of China (English)

    刘爱华; 宋璐; 刘静; 王玉平

    2011-01-01

    目的 观察分析不同年龄段平衡功能的不同表现,以及造成这种差异的主要因素.方法 将109例受试者按年龄划分为青少年组、中青年组和老年组.使用Swaystar检查装置记录7项平衡试验中躯体前后、左右晃动的角位移和晃动总面积.结果 (1)当视觉、本体觉或前庭觉传入信息受到干扰时,老年组平衡功能明显较差;单左腿站立时,老年组躯体晃动幅度明显大于另外两组(P<0.05),然而单右腿站立时,三组之间无统计学差异;(2)青少年阶段的姿势调节主要依赖于视觉.结论 随着年龄的增加,本体觉和前庭觉减退会导致平衡功能的降低;而在青少年时期视觉在姿势调节过程中占主要地位.%Objective The aim of this study was to compare the contributions of possible differences to postural control in different ages. Methods Seven balance tests were administered to 109 subjects,aged between 13 - 79 years. The subjects were divided into three groups according to their age. The ranges of angular displacement in the pitch and roll direction and total angle areas were recorded u-sing Swaystar system. Results (1) Compared with the other two groups,the senior group had a poorer performance when the afferent information of sensory, visual or vestibular systems were disturbed, and had greater sway amplitude in left leg stance test; (2) The adolescent group rely more strongly on vision to stabilize their body. Conclusions We concluded that all of the three factors associated with the postural control,especially the proprioceptive and vestibular systems, showed significant association with age, and attention should be directed toward these phenomena.

  12. Application of Polyaniline Incorporated Carbon Particles Coated Platinum Electrode in Coulometric Titration to Determination of Polyisoprene Alcohol

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ge; LIU Meng; LIU Kuai-zhi; QU Jiang-ying; CHENG Gang; DU Zu-ling

    2003-01-01

    The feasibility of using electrodes modified with polyaniline incorporated carbon particles films for improving the precision of coulometric titration is demonstrated. The problem of large deviation produced during determining polyisoprene by coulometric titration with direct titration technique(double Pt electrodes indicating electrode) has been solved. In the titration process, polyisoprene alcohol, an electro-inactive species, is adsorbed on the surface of the bare Pt electrode, which inhibits the electrode reaction of Br- and Br2. Therefore, when the titration reaches the end-point, the detected current will slowly change with time, which can make the repeatability of end-point poor. The atomic force microscopic images show the morphology of the electrode surface of adsorbing polyisoprene alcohol. The application of the chemically modified electrode instead of the bare Pt electrode to indicating the end-point has been investigated. The results show that the Pt electrode coated with polyaniline incorporated carbon particles films is an excellent indicator electrode. This electrode has advantages that the indicating signals are sharp and repeatable at end-point. The precision and the accuracy of the determination of polyisoprene alcohol are satisfactory.

  13. Proteins contribute insignificantly to the intrinsic buffering capacity of yeast cytoplasm

    Energy Technology Data Exchange (ETDEWEB)

    Poznanski, Jaroslaw [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw (Poland); Szczesny, Pawel [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw (Poland); Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw (Poland); Ruszczynska, Katarzyna [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw (Poland); Zielenkiewicz, Piotr [Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw (Poland); Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw (Poland); Paczek, Leszek, E-mail: leszek.paczek@wum.edu.pl [Department of Immunology, Transplantology and Internal Medicine, Warsaw Medical University, Warsaw (Poland)

    2013-01-11

    Highlights: Black-Right-Pointing-Pointer We predicted buffering capacity of yeast proteome from protein abundance data. Black-Right-Pointing-Pointer We measured total buffering capacity of yeast cytoplasm. Black-Right-Pointing-Pointer We showed that proteins contribute insignificantly to buffering capacity. -- Abstract: Intracellular pH is maintained by a combination of the passive buffering of cytoplasmic dissociable compounds and several active systems. Over the years, a large portion of and possibly most of the cell's intrinsic (i.e., passive non-bicarbonate) buffering effect was attributed to proteins, both in higher organisms and in yeast. This attribution was not surprising, given that the concentration of proteins with multiple protonable/deprotonable groups in the cell exceeds the concentration of free protons by a few orders of magnitude. Using data from both high-throughput experiments and in vitro laboratory experiments, we tested this concept. We assessed the buffering capacity of the yeast proteome using protein abundance data and compared it to our own titration of yeast cytoplasm. We showed that the protein contribution is less than 1% of the total intracellular buffering capacity. As confirmed with NMR measurements, inorganic phosphates play a crucial role in the process. These findings also shed a new light on the role of proteomes in maintaining intracellular pH. The contribution of proteins to the intrinsic buffering capacity is negligible, and proteins might act only as a recipient of signals for changes in pH.

  14. Implementation of 'Davies and Gray/NBL Method' for potentiometric titration of uranium in the Safeguards Laboratory of CNEN by the use of a DL-67 mettler titrator

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Radier Mario Silveira de; Barros, Pedro Dionisio de [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil). Lab. de Salvaguardas]. E-mail: radier@ird.gov.br; pedrodio@ird.gov.br

    2005-07-01

    To meet the requirements of the Brazilian State System of Accounting for and Control of Nuclear Materials - SSAC, the Safeguards Laboratory of CNEN - LASAL has been applying the 'Davies and Gray/NBL' method for potentiometric determination of total uranium concentration in uranium samples taken during safeguards inspections at nuclear facilities since 1984, using a Radiometer ETS 822 titrator. In order to improve the analytical capability and the procedures related to the titration methodology, the same method was also implemented by using a METTLER DL - 67 titrator. This equipment is microprocessor - controlled and can be connected to additional devices such as printers, analytical balances, etc. It also provides accurate and reproducible results for end-point titrations, providing analytical performance according to the current international safeguards requirements. The implementation of the method in such equipment included the addition of analytical data as well as the improvement of the equipment parameters for uranium determination. Parameters like predispensing volume; titrant data and end-point value were studied. Some uranium samples (solids and solutions) were used during the initial tests with the titrator. A solution of pure uranyl nitrate was used as reference sample for this paper. From this, aliquots were analyzed in both Radiometer ETS-822 and METTLER DL-67. Results obtained from each equipment were compared with the reference value of the sample. The comparison showed that results from METTLER DL-67 meets the precision and accuracy requirements for this kind of analysis and led to the conclusion that the performance of this titrator is adequate for the determination of total uranium content in samples of nuclear materials for safeguards purposes. (author)

  15. Study of the interaction between glucosamine hydrochloride and sodium dodecylsulphate micelles using conductometric, isothermal calorimetry, zeta-potential titrations, and NMR NOESY

    OpenAIRE

    Alves,Marcos Roberto de Abreu; VIRTUOSO, Luciano Sindra

    2014-01-01

    The aim of this work was to investigate the influence of an anti-inflammatory agent, the bulky counterion named glucosamine (Gl+), in sodium dodecylsulphate (SDS) in 2 ways: 1) by titration of SDS solutions with different concentrations of Gl+; and 2) by titration of Gl+ with SDS solution with concentration close to the critical micellar concentration (cmc) (7.7 mM). In procedure 1, micellisation study by isothermal titration calorimetry (ITC) showed that the increase in Gl+ concentrat...

  16. Estimation Thermodynamic Properties of Diisooctyl Sebacate Synthesis by Benson Group Contribution Method%Benson基团贡献法估算癸二酸二异辛酯合成的热力学性质

    Institute of Scientific and Technical Information of China (English)

    蒲艳玲

    2016-01-01

    Diisooctyl sebacate was a novel cold-resistant plasticizer. Benson group contribution method was employed to calculate standard molar formation enthalpy, standard molar formation entropy and standard and molar constant pressure heat capacity of sebacic acid, iso-octyl alcohol and diisooctyl sebacate, respectively. Based on above results, changes of enthalpy and entropy of diisooctyl sebacate synthesis were calculated. This work was benefit for further thermodynamic analysis.%癸二酸二异辛酯是一种新型耐寒增塑剂。本文采用Benson基团贡献法估算癸二酸、异辛醇和癸二酸二异辛酯的标准摩尔生成焓、标准摩尔生成熵和标准摩尔定压热容,在此基础上,计算了癸二酸二异辛酯合成过程的焓变和熵变。上述计算将是进一步热力学分析的基础。

  17. 离子液体热物理性质与相行为预测的基团贡献法%Group contribution methods for prediction of thermophysical properties and phase behavior of ionic liquids

    Institute of Scientific and Technical Information of China (English)

    熊焰; 丁靖; 虞大红; 彭昌军; 刘洪来

    2012-01-01

    Ionic liquids (ILs) are molten salts of great industrial interest and are now attracting the attention of a large number of researchers due to their unique characteristics, i.e. , wide liquid range, thermal stability, negligible vapor pressure, tunable physicochemical properties and many others. Thousands of ILs have been designed and synthesized for specific applications in different fields in both academic and industrial studies in the past decades. Thermophysical properties and phase behavior of ILs, such as melting points, densities, gas solubilities, viscosities, conductivities and vapor-liquid equilibrium are required in practical applications. Although a large amount of experimental data have been measured and reported, the number of potential ILs is so enormous, some say as many as 1012 to 1018, that it is impossible to determine all these data by laboratory methods which are complicated, time-consuming and sometimes are even hard to be developed. In recent years, many attempts have succeeded in developing methods to estimate the physical properties of unknown ILs in order to facilitate the design of new modifications and reduce the expenses in experimental work. Group contribution (GC) method is one kind of the successful predicting methods practicable for designing and selecting suitable ILs, in which the property of a compound is a function of structurally-dependent parameters, which are determined by summing the frequency of each group occurring in the molecule times its contribution. Since the number of functional groups is much smaller than the number of molecules, it indicates the great potential opportunity that properties of the whole series of ILs may be predicted rapidly and accurately if only a few data of ILs with similar molecular structure in the series are available. This review highlights a great deal of GC models for prediction of thermophysical properties of ILs, including melting point, viscosity, density, heat capacity, conductivity

  18. Impact of study oximeter masking algorithm on titration of oxygen therapy in the Canadian oxygen trial.

    Science.gov (United States)

    Schmidt, Barbara; Roberts, Robin S; Whyte, Robin K; Asztalos, Elizabeth V; Poets, Christian; Rabi, Yacov; Solimano, Alfonso; Nelson, Harvey

    2014-10-01

    To compare oxygen saturations as displayed to caregivers on offset pulse oximeters in the 2 groups of the Canadian Oxygen Trial. In 5 double-blind randomized trials of oxygen saturation targeting, displayed saturations between 88% and 92% were offset by 3% above or below the true values but returned to true values below 84% and above 96%. During the transition, displayed values remained static at 96% in the lower and at 84% in the higher target group during a 3% change in true saturations. In contrast, displayed values changed rapidly from 88% to 84% in the lower and from 92% to 96% in the higher target group during a 1% change in true saturations. We plotted the distributions of median displayed saturations on days with >12 hours of supplemental oxygen in 1075 Canadian Oxygen Trial participants to reconstruct what caregivers observed at the bedside. The oximeter masking algorithm was associated with an increase in both stability and instability of displayed saturations that occurred during the transition between offset and true displayed values at opposite ends of the 2 target ranges. Caregivers maintained saturations at lower displayed values in the higher than in the lower target group. This differential management reduced the separation between the median true saturations in the 2 groups by approximately 3.5%. The design of the oximeter masking algorithm may have contributed to the smaller-than-expected separation between true saturations in the 2 study groups of recent saturation targeting trials in extremely preterm infants. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Use of isothermal titration calorimetry to study the interaction of short-chain alcohols with lipid membranes

    DEFF Research Database (Denmark)

    Trandum, Christa; Westh-Andersen, Peter; Jørgensen, Kent

    1999-01-01

    of short-chain alcohols on Lipid bilayers. isothermal titration calorimetry (ITC) has been used to determine the energy involved in the association of the alcohols with lipid bilayers. Pure unilamellar DMPC liposomes and DMPC liposomes incorporated with different amounts of cholesterol, sphingomyelin...... dependent on the lipid bilayer composition. In the presence of high concentrations of cholesterol, the binding enthalpy of ethanol is decreased, whereas the presence of ceramides enhances the enthalpic response of the lipid bilayer to ethanol. Isothermal titration calorimetry offers a new methodology...

  20. Isothermal titration calorimetry and surface plasmon resonance allow quantifying substrate binding to different binding sites of Bacillus subtilis xylanase

    DEFF Research Database (Denmark)

    Cuyvers, Sven; Dornez, Emmie; Abou Hachem, Maher

    2012-01-01

    Isothermal titration calorimetry and surface plasmon resonance were tested for their ability to study substrate binding to the active site (AS) and to the secondary binding site (SBS) of Bacillus subtilis xylanase A separately. To this end, three enzyme variants were compared. The first was a cat......Isothermal titration calorimetry and surface plasmon resonance were tested for their ability to study substrate binding to the active site (AS) and to the secondary binding site (SBS) of Bacillus subtilis xylanase A separately. To this end, three enzyme variants were compared. The first...