1,721,055 research outputs found
The ethane-1,2-diol / water solvent system : densities and excess molar volumes at various temperatures
No full textDensities (rho) are presented for aqueous binary mixtures of ethane-1,2-diol at different mole fractions covering the whole miscibility field and at various temperatures (t) in the -10 less-than-or-equal-to t/degrees-C less-than-or-equal-to +80 range. The values of the excess molar volume (V(E)) are discussed in terms of: (i) the influence of interactions between the components; (ii) order and degree of packing in the pure species and in the mixtures; (iii) free volume differences
Densities and excess molar volumes of 2-methoxyethanol / water binary mixtures
No full textDensities (rho) are reported for the 2-methoxyethanol (component 1)/water (component 2) solvent system, over the full composition range (0 less-than-or-equal-to X1 less-than-or-equal-to 1) at temperatures (t) from -10 to +80-degrees-C. The experimental data have been fitted by three empirical relations that represent the functions rho = rho(t), rho = rho(X1), rho = rho(t, Xi), and the excess volume values by a Redlich-Kister equation. The 1:2 2-methoxyethanol/water adduct appears to be stable throughout the temperature range
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Static dielectric constant of N,N-dimethylformamide / 2-methoxyethanol solvent system at various temperatures
No full textMeasurements of static dielectric constants (epsilon) have been made for binary liquid mixtures of N,N-dimethylformamide (DMF)/2-methoxyethanol (ME) at 19 temperatures ranging from -10 to + 80-degrees-C. Some empirical equations of the type epsilon = epsilon(T), epsilon = E(X1), and epsilon = epsilon(T,X1) have been applied to check their validity. The epsilon(E) values, which refer to the deviation of the dielectric constants of the binaries from the values arising from mole fraction mixture law, have been calculated. Deviations from ideal behaviour have been found to be positive at all temperatures. The positive epsilon(E) values are attributed to a specific interaction between unlike molecules, which leads to the formation of complexes between DMF and ME in the liquid state. These nDMF . mME complex moieties were found to have the stoichiometric ratios 2:1, 1:1, and 1:2 in the temperature range of -10 to + 80-degrees-C
THE RELATIVE PERMITTIVITY OF 1,2-ETHANEDIOL PLUS 2-METHOXYETHANOL PLUS WATER TERNARY MIXTURES
No full textThe relative permittivities epsilon for the ternary 1,2-ethanediol (component 1) + 2-methoxyethanol (2) + water (3) solvent system have been measured for 66 mixtures covering the whole mole fraction composition 0 less-than-or-equal-to X1/X2/X3 less-than-or-equal-to 1 range at -10, -5 and 0-degrees-C. The experimental data were used to test some empirical relations stating the dependence of epsilon = epsilon (X1, X2, X3). A comparison between the calculated and experimental data show that these equations can be usefully employed to predict epsilon values in correspondence of the experimental data gaps
THE RELATIVE PERMITTIVITY OF 1,2-DIMETHOXYETHANE WATER SOLVENT MIXTURES FROM -10 TO 80-DEGREES-C
No full textRelative permittivities (epsilon) and the excess property (epsilon(E)) for the binary mixtures formed by 1,2-dimethoxyethane with water have been measured at various temperatures in the range from -10 to +80-degrees-C. These mixtures have interesting properties for electroanalytical applications. Their study should help in understanding the phenomenology of cosolvency towards ionizable and inert solutes. The results of the epsilon(E) analysis are discussed in terms of the influence of interactions between the components, order and degree of packing in the mixtures, and any other structural effect which occurs in solution
N,N-dimethylformamide + 1,2-dimethoxyethane binary mixtures. The static dielectric constant from 40 to 80°C
No full textThe static dielectric constant (epsilon) has been measured at 2 MHz for N,N-dimethylformamide (1), 1,2-dimethoxyethane (2), and their nine binary mixtures covering the whole miscibility field (0 less-than-or-equal-to x1 less-than-or-equal-to 1) in the 40-80-degrees-C temperature range. The experimental epsilon values were fitted by empirical equations of the types epsilon = epsilon(T), epsilon = epsilon(x1), and epsilon = epsilon(T,x1). The mixing quantity deltaepsilon has been evaluated and fitted by a Redlich-Kister equation. The trend of deltaepsilon vs mole fraction curves shows negative deviations from ideality, and makes evident the presence of a stable dipolar interaction between unlike molecules
Kinematic viscosities of 1,2-ethanediol / 1,4-dioxane binary mixtures from -10 to +80 °C
No full textMixture kinematic viscosities (nu) were measured for the 1,2-ethanediol/1,4-dioxane binaries, covering the whole miscibility field (0 less-than-or-equal-to X1 less-than-or-equal-to 1), at 19 temperatures ranging from -10 to +80-degrees-C. The experimental nu values were fitted by different equations, such as Grunberg-Nissan, McAllister, Auslander, Heric, and polynomial one, using pure component properties for the binaries studied. A comparison of the calculated and experimental data shows that all the selected equations can be safely employed to predict the dependence of nu on the composition and on the temperature of the system studied when no binary experimental data are available
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