Size Frequency Analysis Research Articles

The evaluation of the performance of an electrostatic precipitator using a Pollak-Nolan nucleus counter

The performance of an electrostatic precipitator for aerosol sampling was studied experimentally using a Pollak-Nolan photo-electric nucleus counter. Particles of various sizes lying between 1.4–9.6 × 10 −6 cm were investigated. The aerosols were polydisperse. Special attention was given to finding out the fraction of particles in an aerosol which were charged while passing through the precipitator at various flow-rates. The efficiency of the precipitator was measured at different flow-rates for particles of several sizes. It was shown that there was a bias in favour of both small and large particles when sampling a heterogeneous aerosol with the aid of the precipitator. The results were shown to be independent of the original charged condition of the aerosol entering the precipitator and also of the concentration of nuclei in the aerosol. Oversampling by such a precipitator of both the largest and smallest particles present would render it unsuitable for use on the size-frequency analysis of a heterogeneous aerosol by electron microscopy.

The size spectrum of condensation nuclei by a new form of the ionic mobility method

A novel form of ionic mobility spectrometer is described, based on the intrinsic properties of the construction of thePollak-Nolan nucleus counter. It is used for the size-frequency analysis of an artificial aerosol of Aitken nuclei at various stages in its decay. The first, construction of the instrument has been found to perform quite satisfactorily; suggestions for its improvement are discussed.

Application of Rosin's Distribution in Size-frequency Analysis of Clastic Rocks

ABSTRACT Size-frequency distributions of clastic rocks and sediments customarily are described with respect to the log-normal distribution or the normal phi distribution that results from logarithmic transformation of size variates. Clastic materials derived through mechanical disintegration, crushing, or volcanic explosion might be described better in terms of Rosin's law of crushing. A parametric statistical test, based upon regression analysis of size-frequency data and conducted with a digital computer, provides evidence that size-frequency distributions of artificially crushed material fit Rosin's distribution and that distributions of some regolithic, pyroclastic, and glacial debris fit Rosin's distribution with various degrees of approximation. Further use of the technique described may suggest new ways of studying initial fluviatile sorting and the formation of pyroclastic deposits.

バフンウニの成長について

1. The growth rate of the Japanese common littoral sea urchin, Hemicentrotus pulcherrimus (A. AGASSIZ) was studied in the vicinity of the Misaki Marine Biological Station, Kanagawa-ken, Japan. 2. Estimation of its growth rate was made by the combined use of PETERSEN's size frequency analysis, the consecutive observation of the PETERSEN curves and the tagging method. Evaluation of the applicability or these three methods was discussed as applied to the growth rate of this species. The estimates calculated from these methods presented a satisfactory and close agreement. 3. It was found that H. pulcherrimus attains a size of 10mm. in test diameter in the first summer and the modes in the subsequent summers are 21mm. at 2 years, 28mm. at 3 years and 34mm. at 4 years.

The adsorbed film theory and solid stabilized emulsions

It is an established fact that a protective stabilization membrane is invariably formed at the interface during emulsification. The film being invisible, its thickness can be identified only by indirect methods. The thickness of the film has been calculated here from interfacial areas determined by size frequency analysis and it has been found to be of colloidal dimensions. While a special thickness of the film is a prerequisite of emulsion stability, there is lack of connection between the two properties, The varying strengths of the film are due to differences in surface tension ratios and not any other physical characteristic of the system. Although the permanence of an emulsion is determined by nature of the film, its other phyiscal characteristics and adsorption of the ions on the film resulting in electrical forces at the interface are the criteria which seem to have a direct bearing on emulsion stability.

Emulsification With Ultrasonic Waves II : Evaluation of Three Ultrasonic Generators and a Colloid Mill

Three ultrasonic generators and a colloid mill were evaluated with 25 per cent mineral oil, peanut oil, and safflower oil emulsions, each made with four emulsifier systems. Emulsions were exposed in each apparatus for periods up to fifteen minutes. The best of these emulsions were analyzed after zero, fifteen, thirty, and sixty days storage. From the size-frequency analysis data specific interfacial area, mean globule diameter, and standard deviation were calculated. The Minisonic homogenizer produced emulsions distinctly superior to those made on any other apparatus.

A study of olive oil emulsions with solid stabilizers

The present piece of work has revealed that the olive oil emulsions stabilised by solids in certain respects behave in the same manner as the corresponding kerosene emulsions. Thus the degradation of the emulsion on ageing follows the normal course and there are no departures from the general behaviour of kerosene emulsions so far as the matter of lack of action of electrolyte and sensitization by some protective colloids is concerned. But these systems do present some peculiarities. For example, the emulsions of this work are less fine but more stable than the corresponding kerosene emulsions owing to the higher viscosity of the olive oil which makes the dispersion of the globules difficult but prevents them from coalescence. Bordeaux mixture when used as stabilizer exhibits the tendency of emulsifying agent antagonism and formation of multiple emulsion. The former phenomenon is more pronounced with many other emulsions which could not be investigated by size frequency analysis. This is due to the reaction in situ between the basic stabilizing bivalent and trivalent cations and oleic acid constituent of the olive oil with the production of oleates of polyvalent metals which promote reverse type of emulsions. The perplexing fact about these emulsions is that emulsifying agent antagonism is set up with certain solid agents while with other similar compounds it is evaded. As a matter of fact it varies with the mode of precipitation of the same emulsifier. So any general theoretical interpretation is to emerge only after intensive investigations.

On the Supposed Evolution of Gryphaea in the Lias

AbstractA re-examination of Hettangian and Lower Sinemurian oysters has led to the rejection of Trueman's hypothesis on the evolution of Liostrea into Gryphaea. Gryphaea assemblages from two horizons in different parts of Britain have been subjected to bivariate and size frequency analysis. The only detectable difference is a slight size increase up the succession. No “gryphaeoid” trend is discernible in Liostrea up the Hettangian succession and the change to Gryphaea is in consequence abrupt. All the oysters of Trueman's series are referred to what are considered to be two different Linnaean species.

The assessment of specific surface by single‐observation photo‐extinction methods

AbstractIn previous papers, it has been shown that owing to the variation of the ‘extinction coefficient’ with particle size the specific surface of a powder, as determined from the measurement of the total extinction of a suspension of the material, is subject to errors of considerable magnitude.Thus, the convenient method based upon a single measurement of the opacity of the suspension is unsatisfactory where results of even moderate accuracy are required and recourse must then be made to the tedious method in which a size‐frequency curve is obtained and the specific surface is then calculated from these data.In the present paper empirical expressions are derived whereby a value of specific surface in close agreement with that obtained from a size‐frequency analysis may be obtained from a single measurement of the opacity of a suspension of the powder.

Introduction to Emulsions

THIS book is written in the first person in lecture style, and is, in fact, based upon lectures given at the Brooklyn Polytechnic Institute in New York. It is claimed to be written by a practical man for practical men, and, on that account, contains details and explanations which the chemist with a university degree will find superfluous. A bibliography is appended with 159 references ; but no mention is made of G. I. Taylor's work on the physics of emulsion formation, nor of F. A. Cooper's work on size frequency analysis and the chemical engineering aspects of emulsion manufacture. Another extensive appendix gives the commercial name of 182 emulsifying agents produced in the United States, and lists their chemical name or formula, group and emulsion type and manufacturer. The uses of bentonite as an emulsifying agent is only lightly considered. The manufacture of a good emulsion is still somewhat of an art, and the comment that "you cannot learn to ride a bicycle by reading a book" still seems to hold for practical emulsion technology. Introduction to Emulsions By George M. Sutheim. Second printing. Pp. Viii + 260. (Brooklyn, N.Y.: Chemical Publishing Co., Inc.; London: Chapman and Hall, Ltd., 1947.) 21s. net.

The Separation and Emission of Cinders and Fly Ash

Abstract The author discusses the size-frequency analysis of cinders and fly ash, and the variation of the efficiency of dust separation with varying dust-particle size. He shows how these two factors may be combined to determine the overall efficiency of separation. He outlines a rational method for the calculation of dust separation and emission in complex fuel-burning units, in which the dust originates in the furnace, and must pass, prior to its emission into the atmosphere, through numerous heat-absorbing units, including some in which a measure of dust removal may occur. He points out what experimental data must be made available to designers before they may fully utilize any method of predetermining the operating characteristics of equipment with respect to cinder and fly-ash emission. He attempts a theoretical analysis of the efficiency of dust separation in settling chambers, centrifugal concentrators, and cyclone separators.