Determination Of Volume Changes Research Articles

Portland cement curing and volume characteristics

This paper describes the volume change characteristics of neat portland cement paste as used in the assembly of high voltage porcelain insulators. Many tests were made to determine volume changes under a variety of physical conditions. The effect on the electrical and mechanical integrity of the insulators subjected to these cement volume changes was investigated and reported.

Light scattering from suspensions of membrane fragments derived from sonication of beef heart mitochondria.

The intensity of light scattering from suspensions of membrane fragments prepared by sonication of beef heart mitochondria in the presence of EDTA at alkaline pH (ESMP) was determined at 45, 90, and 135 degrees with light of wavelength 546 nm. The dissymmetry ratio Z = I45 degrees c/I135 degrees c, where I45 degrees c and I135 degrees c are the scattering intensities at 45 and 135 degrees extrapolated to zero particle concentration and corrected for reflectance effects, was used to calculate particle size from the Rayleigh-Gans-Debye theory. An average particle diameter D of 184-190 nm was obtained, within the range of particle diameter 50-300 nm determined previously by electron microscopy. This average diameter determined by light scattering is a useful parameter for characterization of ESMP particle size. We propose the term: light scattering average particle diameter, DLS, for this parameter. The refractive index of ESMP was determined to be 1.443 by measurement of scattering intensity in buffer solutions of varying sucrose concentration. The value of Z was independent of sucrose concentration in this determination, showing that the particles are osmotically inactive toward sucrose. The values of average particle diameter DLS and of refractive index fall within the range of validity of the Rayleigh-Gans-Debye theory, for which light scattering changes are attributable solely to dimension change, rather than to change in particle refractive index. Uptake of water accompanying energy-linked salt uptake in ESMP was calculated from light scattering changes to be 0.18 mul of H2O/mg of protein, compared with 0.49 mul of H2O/mg of protein measured by dextran inaccessibility. Measurement of light scattering changes provides a rapid and sensitive method for determining volume changes of ESMP. The magnitude of the volume change observed during energy-linked water and salt uptake and the initial degree of hydration suggests that ESMP are analogous to polyelectrolyte gels with regard to sorption of strong electrolytes and that the Donnan formulation for ion exchange equilibria may be usefully applied to these processes in ESMP.

Lysophospholipid induced volume changes in lysosomes and in lysosomal lipid dispersions

A Coulter Counter is used to determine volume changes induced by lysophospholipids in lysosomes, in lysosomal lipid dispersions and in dispersions of pure egg yolk lecithin with added lysolecithin. In each case the increased lysophospholipid content causes an increase in the particle volume along with a decrease in the total number of particles. It is suggested that these volume changes may result from lysosomal or lipid membrane fusion induced by the lyso-compounds.

18] Dilatometry

This chapter focuses on dilatometry that discusses the measurement of volume changes produced by a system as a consequence of physical and/or chemical change. These volume effects reflect the changes of the partial molar volume of some or all of the components in the system. Dilatometry apparatus is generally designed to permit the continuous monitoring of a reaction or process. Thus, this technique provides a convenient method for determining the kinetics of the system under study. Dilatometry has been used to study the kinetics of reactions, phase transitions in polymers, enzymatically catalyzed reactions, and more recently, structural changes in proteins. The current era of dilatometry in biochemistry resulted from the simplification of Sreenivasaya's dilatometer by Linderstrom-Lang and Lanz. This unit proved to be capable of measuring volume changes with a reproducibility of ± 0.02 μl, providing that the temperature is maintained to within 0.001°. Because densitometric analysis can be used to determine volume changes, it is appropriate to compare these two techniques.

Expansion of the inner membrane compartment and its relation to mitochondrial volume and ion transport.

Glutaraldehyde has been used to fix mitochondria undergoing rapid volume changes associated with energized ion transport under oscillatory state conditions and valinomycin-induced potassium uptake. Fixation was found to prevent structural changes which normally occur during ion accumulation or loss. By correlating packed volume measurements with electron microscopy, it is shown that changes in volume associated with ion movements reflect changes in the inner membrane compartment and that this compartment can be related to the sucrose inaccessible space. The method can therefore be used to accurately determine volume changes that arise from ion translocation.

Limitations of electric impedance plethysmography.

Electric impedance plethysmography has been offered as a substitute for mechanical plethysmography and would be particularly suitable for regions in which the mechanical method cannot be applied. A comparative investigation of mechanical and impedance plethysmograms, taken simultaneously from a finger or a forearm, revealed that, while the normal pulsations were reproduced reasonably well, electric impedance plethysmography cannot be employed to determine volume changes following venous occlusion. The reasons are discussed.

A New Method of Plethysmometry

The method herein described is designed to eliminate some disadvantages of the standard plethysmograph, particularly the necessity of enclosing the object to be measured in a water-tight container through a tightly-fitting rubber cuff.∗ The new procedure makes it possible to determine volume changes in an open container. This is of particular interest in the clinical determination of blood flow through extremities where speed and ease with which the measurement can be performed are very desirable. The use of an open vessel offers an easy access to the extremity during the measurement and makes it possible to remove and reimmerse it within a short time, which is of advantage in experimental work.The apparatus to be described can easily be assembled from standard parts available in any physiological laboratory. It requires a balance and a container large enough for the immersion of the object to be measured.The principle upon which this method is based can be considered a supplement to the principle of Arch...

A new differential dilatometer for the determination of volume changes during solidification

In recent years, the practical requirements of the metal industries have made it necessary to study the factors which govern the production of good castings. One of the most important of these factors is the change of volume which accompanies solidification. The experimental methods which have hitherto been used to determine this change have given discordant results, and it has seemed desirable to devise a new method, less liable to error. The new form of volumenometer which is the subject of this paper is intended to eliminate most of the errors inherent in the older methods. It has been applied to the measurement of the volume changes of two eutectic alloys, those of lead and tin and of tin and bismuth, the former of which contracts during solidification, whilst the latter shows a distinct expansion. The results indicate that the method is trustworthy. Previous Methods of Measurement . The older methods, which have been used for the experimental determination of the changes in volume, associated with the change in state of bodies, may be divided into the following classes:— ( a )The coefficients of expansion of the solid and liquid, over limited ranges of temperature, are measured and the volume change occurring at the melting point is found by extrapolation. The coefficient of expansion of the solid is found either by direct measurement of the linear expansion or deduced from measurements derived from some hydrostatic method in which Archimedes’ Principle is employed. The expansion of the liquid melt is inferred from observations on some dilatometric or hydrostatic method.