Search results for "strength"
showing 10 items of 2415 documents
Using tools effectively despite defective hand posture: A single-case study.
2019
Apraxia, a cognitive disorder of motor control, can severely impair transitive actions (object-related) and may lead to action errors (e.g., rubbing a hammer on a nail instead of pounding it) and hand posture errors (e.g., grasping a tool in a wrong way). Here, we report a rare observation of a left-handed patient, left-lateralized for language, who developed a severe apraxia following a right brain lesion. Interestingly the patient showed a significant number of hand posture errors, while she perfectly demonstrated the actual use of tools. This case stressed the predictions made by the current theories of tool use. According to the manipulation-based approach, the hand posture errors shoul…
Tecnhiques for sentiment analysis in Twitter: Supervised Learning and SentiStrength
2017
[EN] Sentiment analysis on Twitter offers possibilities of great interest to evaluate the currents of opinion disseminated through this medium. The huge volumes of texts require tools able to automatically process these messages without losing reliability. This paper describes two different types of approaching this problem. The first strategy is based on Supervised Learning processes, developed in the field of artificial intelligence. Its application requires some tools from natural language processing along with a classifed corpus as a starting point. The second approach is based on polarity dictionaries. SentiStrength tool is located in this line. It is increasingly applied to studies of…
Solubility and stability of liebigite, Ca2UO2(CO3)3·10H2O(cr), in dilute to concentrated NaCl and NaClO4 solutions at T = 22–80 °C
2019
Abstract The solubility and thermodynamic stability of a synthetic liebigite was investigated in NaCl and NaClO4 solutions within a wide range of ionic strength (0.03 m ≤ Im ≤ 5.61 m), pH (7 ≤ pHm ≤ 9, with pHm = –log [H+]) and temperature (22 °C ≤ T ≤ 80 °C) conditions. A comprehensive characterization of the synthetic solid phase using XRD, quantitative chemical analysis, TG–DTA, SEM–EDS, IR and Raman spectroscopy confirmed the stoichiometry of Ca2UO2(CO3)3·10H2O(cr). At room temperature, liebigite remains stable and controls the solubility of U(VI) in the investigated NaCl and NaClO4 systems with Im ≤ 0.51 m. For the same temperature but high ionic strength (5.61 m NaCl), liebigite trans…
The interaction of amino acids with the major constituents of natural waters at different ionic strengths
2000
Abstract The interaction of amino acids with the major constituents of natural waters has been studied potentiometrically by determining protonation constants at different ionic strengths (e.g., I ≤5.6 mol (kg H 2 O) −1 (NaCl)) and in artificial seawater (containing Na + , K + , Ca 2+ , Mg 2+ , Cl − and SO 4 2− ) at different salinities. For glycine determinations in mixed NaCl–MgCl 2 , electrolyte solutions were also performed. The data included in this work, together with some already published, make it possible to calculate parameters for dependence on ionic strength using different models, i.e. an extended Debye–Huckel type equation and Pitzer equations. The results can be interpreted b…
Hydrolysis of dioxouranium(VI): a calorimetric study in NaClaq and NaClO4aq, at 25°C
2004
Abstract We report the results of a calorimetric study on the hydrolysis of UO 2 2+ in different ionic media (NaClO 4 aq , NaCl aq ) at 25 °C. Experiments in NaCl were performed at different ionic strength, at I ≤1 mol l −1 . The species considered in both ionic media were UO 2 (OH) + , (UO 2 ) 2 (OH) 2 2+ and (UO 2 ) 3 (OH) 5 + , and in addition (UO 2 ) 3 (OH) 4 2+ and (UO 2 ) 3 (OH) 7 − in NaCl aq . The dependence on ionic strength of enthalpy changes in NaCl aq was expressed by the simple linear equation Δ H pq =Δ H ° pq + aI 1/2 ( a , empirical parameter). Comparison with literature findings is given and some recommended values are reported.
Polyacrylate Protonation in Various Aqueous Ionic Media at Different Temperatures and Ionic Strengths
2000
The protonation constants of the polyacrylate anion (molecular mass 2000 Da) in Et4NI, Me4NCl, LiCl, LiNO3, NaCl, NaNO3, and KCl aqueous solution, were determined in a wide range of ionic strengths. A three-parameter approximation was used to express protonation constants as a function of the dissociation degree α, and their dependence on ionic strength was considered using a simple polynomial expansion. Differences in log KH between different data in different media were interpreted in terms of weak complex formation between polyacrylate and alkali metal cations. Measurements were also performed at different temperatures (15 ≤ T/°C ≤ 55) in order to calculate enthalpy and entropy changes f…
Calculation of the pH and the titratable acidity in clinically used infusion solutions.
2006
Clinically used infusion solutions are complex aqueous mixtures composed of a variety of different salts, acids, and non-electrolytes, and are characterized by composition, initial pH, and titratable acidity (TA). By rigorous treatment as a multi-composed acid-base system, pH and TA were calculated from proton dissociation equilibria, mass balance equations and electroneutrality condition. Nine were arbitrarily chosen as model solutions in which pH and TA were experimentally determined. From composition, and based on a set of apparent acidity constants (pK values) at 37 degrees C and total ionic strength 0.155 mol/l, pH was calculated by iteration. In the model solutions, measured pH was in…
Sequestration of organometallic compounds by natural organic matter. binding of trimethyltin(IV) by fulvic and alginic acids
2006
The binding capacity of fulvic and alginic acids towards trimethyl tin(IV) cation was quantitatively determined in order to evaluate the sequestering ability of toxic organometallic compounds by natural organic matter. Investigations were performed in the pH range of natural waters (5–8.5) where the carboxylate groups, largely present in both sequestering agents, are the main binding sites. A chemical interaction model, according to which both the protonation of polyelectrolyte ligands and the hydrolysis of the organotin cation in NaCl aqueous solution were considered, was used to define the speciation of the systems under investigation. Measurements performed at different ionic strength va…
Mark-Houwink Parameters of Biosynthetic Poly(γ-glutamic acid) in Aqueous Solution
2001
A combined viscosity–light scattering–gel permeation chromatography (GPC) study was carried out on bacterially produced poly(γ-glutamic acid) (PGGA). PGGA samples with weight-average molecular weights ranging from 8×104 up to 8×105 g·mol–1 dissolved in phosphate buffer at 0.13 M ionic strength were used. It was found that the Mark–Houwink relation is acceptably obeyed, giving K and a values of 1.84×10–6 dL·g–1 and 1.16, respectively. As expected, GPC analysis showed that PGGA does not follow the universal calibration plot and that deviations can not be avoided by modifying the ionic strength.
Protonation thermodynamics of 2,2'-bipyridyl in aqueous solution. Salt effects and weak complex formation
1993
Abstract Protonation constants of 2,2'-bipyridyl (bipy) have been determined potentiometrically, using (H + )-glass electrode, in different aqueous media (alkali and alkaline earth chlorides, tetramethylammonium chloride and tetramethylammonium iodide) at different temperatures and ionic strengths. The differences in log K H values are explained using a complex formation model. Formation thermodynamic parameters are given.