Densities

The visual processing of text occurs spontaneously in most readers. Dyslexic persons, however, often report both somatic symptoms and perceptual distortions when trying to read. It is possible that the perceptual distortions experienced by those with dyslexia reflect a disturbance in the basic mechanisms supporting perceptual organization at the early stages of visual processing. Integration of information over extended areas of visual space can be measured psychophysically in a task that requires the detection of a path defined by aligned, spatially narrow-band elements on a dense field of otherwise similar elements that are randomly oriented and positioned. In the present study a contour integration task was used to investigate such perceptual organization in dyslexia. The detection of contours or paths composed of Gabor micropatterns was performed within a field of randomly oriented distracter elements in a 2-alternate forced choice (AFC) task. The stimuli were manipulated by ran...

The densities ρ, and viscosities η, of pure toluene, cyclohexane, and n-hexane and those of their binary and ternary mixtures have been measured at 298.15 K and atmospheric pressure over the entire range of compositions. Excess molar volumes V123E, viscosity deviations Δη123, and excess Gibbs energy of activation G123*E, were obtained from the experimental results and those values for the binary and ternary systems were fitted to Redlich–Kister's and Cibulka's type function in terms of mole fractions. The V123E data were positive and Δη123 and G123*E, values were negative. Several semi-empirical relations are used to predict the ternary excess molar volumes and viscosity deviations from experimental results on the constituted ternary and analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.

Entre finales de marzo y finales de abril de 1982, se visitaron 16 hatos en los estados Apure, Barinas y Portuguesa, Venezuela, los cuales cubren una superficie total de 233.769 ha, con el objeto de establecer la situación de las poblaciones de babas (Caiman crocodilus). La estimación del número de babas de más de un año se hizo en base a conteos nocturnos y/o nocturnos. Los conteos diurnos (13.385 individuos) permitieron discriminar a los animales de acuerdo a su longitud cabeza-cloaca (LCC): Clase II (20 cm ≤  LCC <60 cm) con 17.6% de los individuos, Clase III (60 cm ≤  LCC < 90 cm) con 65% y Clase IV (LCC ≥ 90 cm) con 17.4%. El número de babas contadas de noche fue 3.29 veces mayor que el contado de día para aquellos cuerpos de agua con ambos procedimientos. La población mínima estimada para todas las fincas fue de 55,072 individuos. La relación entre el número de individuos estimados y la superficie total fue de 0.24 ind/ha. Esta relación, al considerar la superficie efectiva total o superficie de los cuerpos de agua, fue de 205 ind/ha. Estas cifras son comparadas con las obtenidas por otros investigadores en otros lugares de Venezuela.

An efficient and convenient method for predicting the crystalline densities of energetic materials was established based on the quantum chemical computations. Density functional theory (DFT) with four different basis sets (6-31G**, 6-311G**, 6-31+G**, and 6-311++G**) and various semiempirical molecular orbital (MO) methods have been employed to predict the molecular volumes and densities of a series of energetic nitramines including acyclic, monocyclic, and polycyclic/cage molecules. The relationships between the calculated values and experimental data were discussed in detail, and linear correlations were suggested and compared at different levels. The calculation shows that if the selected basis set is larger, it will expend more CPU (central processing unit) time, larger molecular volume and smaller density will be obtained. And the densities predicted by the semiempirical MO methods are all systematically larger than the experimental data. In comparison with other methods, B3LYP/6-31G** is most accurate and economical to predict the solid-state densities of energetic nitramines. This may be instructive to the molecular designing and screening novel HEDMs.

The present work reports the results of densities, ρ, viscosities, η, ultrasonic speeds, u, and refractive indices, n, of pure styrene (STY), acetone (ACT) and dimethylsulphoxide (DMSO) and of their binary liquid mixtures over the entire composition range at 298.15, 303.15, 308.15, and 313.15 K. The excess molar volumes, V E , excess intermolecular free lengths, , deviations in isentropic compressibilities, Δk s , viscosities, Δη, and in refractive indices, Δn were calculated from the experimental data. Partial molar volumes, , and partial molar compressibilities, , of ACT and DMSO in styrene at infinite dilution and at different temperatures have been evaluated. Apart from using density data for the calculation of V E , excess molar volumes have also been estimated by using the Flory&#39;s statistical theory and refractive index measurements.

Density data for very diluted aqueous solutions of proline-leucine are reported for eight different temperatures from (283.15 to 318.15) K. Measurements were made using a vibrating tube densimeter. Apparent molar volumes of the dipeptide were calculated, at ...

The densities (ρ) and speeds of sound (u) have been measured over the whole composition range for (butan-1-ol with hexane, or octane, or decane) at T = (298.15, 303.15, and 308.15) K and atmospheric pressure along with the properties of the pure components. Viscosities ...

ABSTRACT Boron carbide (B4C) powder has been densified by a method of rapid powder consolidation known as Plasma Pressure Compaction (P4C). This process offers the ability to subject the powder to a pulsed DC voltage, which is believed to generate interparticle plasma that acts to break down contaminant layers on particle surfaces. Uniaxial pressure and high-current continuous DC voltage are then applied to achieve consolidation. Three types of B4C powders with differing size distributions were characterized, then each was consolidated by the P2C method in air. Densities of samples increased with consolidation temperature. Higher densities were also achieved by using powder with a smaller particle size. Pulsing of the powder appeared to have no effect on the final density. Samples were consolidated by P2C to densities equal to those achieved by conventional hot pressing, but at a temperature of 4000°CC lower, 15 MPa less pressure, and 1/9 of the hold time.