The Experts below are selected from a list of 120795 Experts worldwide ranked by ideXlab platform
Claudio Airoldi - One of the best experts on this subject based on the ideXlab platform.
-
chitosan cyanuric chloride intermediary as a source to incorporate molecules Thermodynamic Data of copper biopolymer interactions
Thermochimica Acta, 2009Co-Authors: Elaine C N Lopes, Kaline S Sousa, Claudio AiroldiAbstract:Abstract The reaction of a chitosan–cyanuric chloride (ChC) intermediate with ethylenediamine (d) and diethylenetriamine (t) molecules yielded the new biopolymers ChCd and ChCt, which were characterized by elemental analysis, thermogravimetry, X-ray diffractometry, scanning electron microscopy and infrared and C13 nuclear magnetic resonance spectroscopies. The precursor chitosan (Ch) and all derivatives adsorb copper from aqueous solution at 298 ± 1 K, determined using a batchwise procedure. The results were fitted to a modified Langmuir equation. The ability to adsorb copper is dependent on the availability of the basic nitrogen atoms attached to the pendant biopolymer chains in the order ChCt > ChCd > ChC > Ch, as given by the values 2.84 ± 0.03, 2.62 ± 0.05, 2.55 ± 0.04 and 2.09 ± 0.03 mol g−1, respectively. The same interactive process was also followed through calorimetric titration at 298.15 ± 0.20 K. The net thermal effects were also adjusted to a modified Langmuir equation to give the Thermodynamic Data at the solid/liquid interface. The exothermic enthalpic values were −28.98 ± 0.05, −32.77 ± 0.04, −60.60 ± 0.03 and −56.41 ± 0.05 kJ mol−1 for the biopolymers Ch, ChC, ChCd and ChCt, respectively. The spontaneity of the systems is shown by the negative ΔG values, −21.1 ± 0.1, −22.1 ± 0.1, −22.1 ± 0.1 and 23.4 ± 0.1 kJ mol−1 for the same sequence. The negative entropic values −26 ± 1, −36 ± 1, −129 ± 1 and −111 ± 1 J mol−1 K−1 indicate an ordering of solvent as complexation occurred. The Thermodynamic Data demonstrate the capability of these biopolymers for cation removal from aqueous solutions, being new derivative biomaterials that may act as useful agents to renew an ecosystem.
-
some Thermodynamic Data about amino chrysotile derivatives with nickel and cobalt cation interactions in aqueous solution
Thermochimica Acta, 2001Co-Authors: Maria G Fonseca, Jose De Alencar Simoni, Claudio AiroldiAbstract:Abstract Two silylating agents yielded aminopropyl and propylethylenediamine chrysotile derivative fibers named CRI1 and CRI2. The amount of organic groups of 1.20 and 2.87 mmol per gram of the fibers, were anchored on surface, respectively. The interactions between the amino groups attached to organic chains of these modified chrysotiles and divalent nickel or cobalt cations in aqueous solution were followed through calorimetric titrations. The thermal effect obtained from the interactive process was subtracted the respective thermal effect of dilution, which net value was adjusted to a modified Langmuir equation. The adsorption capacities were more pronounced for CRI1 and both processes were associated with complexes formation and the calorimetric Data showed two defined steps for this fiber. The enthalpy of interaction was calculated to give the following values for CRI2: −78.61±0.36 and −179.18±6.44 kJ mol −1 for nickel and cobalt. Exothermic Data for CRI1 contrasted to the previous values, giving 35.53±0.50 kJ mol −1 for nickel and 25.73±0.64 kJ mol −1 for cobalt, which value is related to two individual contributions of 13.94±0.42 and 11.79±0.22 kJ mol −1 . The negative Gibbs free energy values indicated a more favorable reaction for CRI2. A linear correlation was obtained between Gibbs free energy and Pearson’s parameters related to hard–soft properties, suggesting that these processes can be adjusted to acidic–basic interactions. By including copper, the sequence of acidic hardness was Co 2+ >Ni 2+ >Cu 2+ , which is the same order of free energy values found for both investigated systems.
Samy O Meroueh - One of the best experts on this subject based on the ideXlab platform.
-
pdbcal a comprehensive Dataset for receptor ligand interactions with three dimensional structures and binding Thermodynamics from isothermal titration calorimetry
Chemical Biology & Drug Design, 2008Co-Authors: Justin J Dantzer, Jonathan Nowacki, Brian J Ocallaghan, Samy O MerouehAbstract:Compounds designed solely based on structure often do not result in any improvement of the binding affinity because of entropy-enthalpy compensation. Thermodynamic Data along with structure provide an opportunity to gain a deeper understanding of this effect and aid in the refinement of scoring functions used in computational drug design. Here, we scoured the literature and constructed the most comprehensive hand-curated calorimetry Dataset to date. It contains Thermodynamic and structural Data for more than 400 receptor-ligand complexes. The Dataset can be accessed through a web interface at http://www.pdbcal.org. The Thermodynamic Data consists of free energy, enthalpy, entropy and heat capacity as measured by isothermal titration calorimetry (ITC). The Dataset also contains the experimental conditions that were used to carry out the ITC experiments. The chemical structures of the ligands are also provided. Analysis of the Data confirms the existence of enthalpy-entropy compensation effect for the first time using strictly ITC Data.
Valerie Vallet - One of the best experts on this subject based on the ideXlab platform.
-
thermochemistry of ruthenium oxyhydroxide species and their impact on volatile speciations in severe nuclear accident conditions
Journal of Physical Chemistry A, 2016Co-Authors: Faoulat Miradji, Francois Virot, Sidi Souvi, Laurent Cantrel, Florent Louis, Valerie ValletAbstract:Literature Thermodynamic Data of ruthenium oxyhydroxides reveal large uncertainties in some of the standard enthalpies of formation, motivating the use of high-level relativistic correlated quantum chemical methods to reduce the level of discrepancies. Reaction energies leading to the formation of all possible oxyhydroxide species RuOx(OH)y(H2O)z have been calculated for a series of reactions combining DFT (TPSSh-5%HF) geometries and partition functions, CCSD(T) energies extrapolated to the complete basis set limits. The highly accurate ab initio Thermodynamic Data were used as input Data of Thermodynamic equilibrium computations to derive the speciation of gaseous ruthenium species in the temperature, pressure and concentration conditions of severe nuclear accidents occurring in pressurized water reactors. At temperatures lower than 1000 K, gaseous ruthenium tetraoxide is the dominating species, between 1000 and 2000 K ruthenium trioxide becomes preponderant, whereas at higher temperatures gaseous ruthen...
James J Harynuk - One of the best experts on this subject based on the ideXlab platform.
-
quantitative structure retention relationship modeling of gas chromatographic retention times based on Thermodynamic Data
Journal of Chromatography A, 2014Co-Authors: Heshmatollah Ebrahiminajafabadi, Teague M Mcginitie, James J HarynukAbstract:Thermodynamic parameters of ΔH(T0), ΔS(T0), and ΔCP for 156 compounds comprising alkanes, alkyl halides and alcohols were determined for a 5% phenyl 95% methyl stationary phase. The determination of Thermodynamic parameters relies on a Nelder-Mead simplex optimization to rapidly obtain the parameters. Two methodologies of external and leave one out cross validations were applied to assess the robustness of the estimations of Thermodynamic parameters. The largest absolute errors in predicted retention time across all temperature ramps and all compounds were 1.5 and 0.3s for external and internal sets, respectively. The possibility of an in silico extension of the Thermodynamic library was tested using a quantitative structure-retention relationship (QSRR) methodology. The estimated Thermodynamic parameters were utilized to develop QSRR models. Individual partial least squares (PLS) models were developed for each of the three classes of the molecules. R(2) values for the test sets of all models across all temperature ramps were larger than 0.99 and the average of relative errors in retention time predictions of the test sets for alkanes, alcohols, and alkyl halides were 1.8%, 2.4%, and 2.5%, respectively.
-
a standardized method for the calibration of Thermodynamic Data for the prediction of gas chromatographic retention times
Journal of Chromatography A, 2014Co-Authors: Teague M Mcginitie, Heshmatollah Ebrahiminajafabadi, James J HarynukAbstract:Abstract A new method for calibrating Thermodynamic Data to be used in the prediction of analyte retention times is presented. The method allows Thermodynamic Data collected on one column to be used in making predictions across columns of the same stationary phase but with varying geometries. This calibration is essential as slight variances in the column inner diameter and stationary phase film thickness between columns or as a column ages will adversely affect the accuracy of predictions. The calibration technique uses a Grob standard mixture along with a Nelder–Mead simplex algorithm and a previously developed model of GC retention times based on a three-parameter Thermodynamic model to estimate both inner diameter and stationary phase film thickness. The calibration method is highly successful with the predicted retention times for a set of alkanes, ketones and alcohols having an average error of 1.6 s across three columns.
Michael Frenkel - One of the best experts on this subject based on the ideXlab platform.
-
new global communication process in Thermodynamics impact on quality of published experimental Data
Journal of Chemical Information and Modeling, 2006Co-Authors: Michael Frenkel, Robert D Chirico, Vladimir Diky, Chris D Muzny, Qian Dong, Kenneth N Marsh, J H Dymond, W A Wakeham, Stephen E Stein, E KonigsbergerAbstract:Thermodynamic Data are a key resource in the search for new relationships between properties of chemical systems that constitutes the basis of the scientific discovery process. In addition, Thermodynamic information is critical for development and improvement of all chemical process technologies. Historically, peer-reviewed journals are the major source of this information obtained by experimental measurement or prediction. Technological advances in measurement science have propelled enormous growth in the scale of published Thermodynamic Data (almost doubling every 10 years). This expansion has created new challenges in Data validation at all stages of the Data delivery process. Despite the peer-review process, problems in Data validation have led, in many instances, to publication of Data that are grossly erroneous and, at times, inconsistent with the fundamental laws of nature. This article describes a new global Data communication process in Thermodynamics and its impact in addressing these challenges...
-
global communications and expert systems in Thermodynamics connecting property measurement and chemical process design
Pure and Applied Chemistry, 2005Co-Authors: Michael FrenkelAbstract:Unprecedented growth in the number of custom-designed software tools for engi- neering applications has created an interoperability problem between the formats and struc- tures of Thermodynamic Data files and required input/output structures designed for applica- tion software products. Various approaches for standardization of thermophysical and thermochemical property Data storage and exchange are analyzed in this paper. Emphasis is made on the development of the XML-based IUPAC standard for Thermodynamic Data com- munications: ThermoML. A new process for global Data submission and dissemination in the field of Thermodynamics based on ThermoML and Guided Data Capture software is de- scribed. Establishment of the global submission and dissemination process for Thermodynamic Data lays the foundation for implementation of the new concept of dynamic Data evaluation formulated at NIST/TRC, which requires the development of large electronic Databases ca- pable of storing essentially all "raw" experimental Data known to date with detailed descrip- tions of relevant metaData and uncertainties. The combination of these Databases with expert software designed primarily to generate recommended Data based on available "raw" exper- imental Data and their uncertainties leads to the possibility of producing Data compilations automatically "to order", forming a dynamic Data infrastructure. Implementation of the dy- namic Data evaluation concept for pure compounds in the new NIST/TRC ThermoData Engine software is discussed.
