scholarly journals The molecular fields of hydrogen, nitrogen and neon

1926 ◽  
Vol 112 (760) ◽  
pp. 214-229 ◽  
Keyword(s):  
Special Interest ◽  
Power Laws ◽  
Experimental Information ◽  
Repulsive Force ◽  
Independent Method ◽  
Molecular Field ◽  
Cohesive Force ◽  
Inverse Power ◽  
Molecular Fields

Since the publication of some recent papers on molecular fields, some new experimental information has become available, which permits of further determinations of the forces between molecules. Hydrogen, nitrogen and neon are now added to the list of gases whose isotherms have been obtained by the precise methods of Holborn and Otto. The publication of these results for neon is of special interest, because one determination of the molecular field of neon has already been made, and it is valuable to have another independent method of attacking the same problem. A method of determining molecular fields from measurements of the isotherms of a gas has been described in an earlier paper. It proceeds on the assumption that the molecular field is spherically symmetrical and that it can be expressed in terms of inverse power laws, one to represent the repulsive force and one to represent the cohesive force. The method shows whether any particular model is a suitable one or not, and when it is, leads to a determination of the force constants.

scholarly journals On the determination of molecular fields. —II. From the equation of state of a gas

1924 ◽  
Vol 106 (738) ◽  
pp. 463-477 ◽  
Keyword(s):  
Equation Of State ◽  
Molecular Model ◽  
Virial Coefficients ◽  
Preceding Paper ◽  
Molecular Field ◽  
Inverse Power ◽  
Theoretical Expression ◽  
Inverse Power Law ◽  
Special Cases ◽  
Molecular Fields

The investigation of a preceding paper has shown that the temperature variation of viscosity, as determined experimentally, can be satisfactorily explained in many gases on the assumption that the repulsive and attractive parts of the molecular field are each according to an inverse power of the distance. In some cases, in argon, for example, it was further shown that the experimental facts can be explained by more than one molecular model, from which we inferred that viscosity results alone are insufficient to determine precisely the nature of molecular fields. The object of the present paper is to ascertain whether a molecular model of the same type will also explain available experimental data concerning the equation of state of a gas, and if so, whether the results so obtained, when taken in conjunction with those obtained from viscosity, will definitely fix the molecular field. Such an investigation is made possible by the elaborate analysis by Kamerlingh Onnes of the observational material. He has expressed the results in the form of an empirical equation of state of the type pv = A + B/ v + C/ v 2 + D/ v 4 + E/ v 6 + F/ v 8 , where the coefficients A ... F, called by him virial coefficients , are determined as functions of the temperature to fit the observations. Now it is possible by various methods to obtain a theoretical expression for B as a function of the temperature and a strict comparison can then be made between theory and experiment. Unfortunately the solution for B, although applicable to any molecular model of spherical symmetry, is purely formal and contains an integral which can be evaluated only in special cases. This has been done up to now for only two simple models, viz., a van der Waals molecule, and a molecule repelling according to an inverse power law (without attraction), but it is shown in this paper that it can also be evaluated in the case of the model, which was successful in explaining viscosity results. As the two other models just mentioned are particular cases of this, the appropriate formulæ for B are easily deduced from the general one given here.

scholarly journals On the forces between atoms and ions

1925 ◽  
Vol 109 (752) ◽  
pp. 584-597 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Electronic Structure ◽  
Physical Properties ◽  
Power Laws ◽  
Experimental Information ◽  
Inverse Power ◽  
Rigid Spheres ◽  
Preliminary Step ◽  
Starting Point ◽  
Repulsive Part

The ultimate knowledge which we can hope to derive from many of the physical properties of gases and crystals is that which concerns the nature of the forces between the constituent atoms and ions. In terms of these forces many diverse phenomena both of gases and solids should be explicable. In some recent researches the writer has sought to determine the repulsive part of the forces between certain atoms and ions in terms of inverse power laws. This representation is considered superior to the treatment of atoms and ions as rigid spheres with definite diameters, as is generally done, for it permits of the correlation of the physical properties of a gas with those of certain associated crystals. Thus the forces which explain the thermal conductivity of neon have been shown to explain as well the observed spacing constants of crystals like NaF and MgO. These researches had their starting point in an investigation of certain physical properties of the pure gases, and this formed a necessary preliminary step to the later work on crystals. The methods there developed were, however, applicable only to neon and argon, for only in those cases was the necessary experimental information available. Consequently the later extension to include the forces of ions applied only to ions of similar electronic structure to these gases.

DETERMINATION OF THE REPULSIVE FORCE OF A THICK HIGH-COERCIVE PERMANENT MAGNETS IN THE AXIAL BEARING OF A VERTICAL PUMP

2021 ◽  
pp. 23-27
Author(s):  
A. Ya. Krasil’nikov ◽  
A. A. Krasil’nikov
Keyword(s):  
Standard Method ◽  
Permanent Magnets ◽  
Magnetic System ◽  
Repulsive Force ◽  
Cobalt Alloy ◽  
Average Value ◽  
The North ◽  
Repulsive Forces ◽  
North And South

The article considers the possibility of applying a standard method for calculating the repulsive force for a thick high-coercive permanent magnets from samarium-cobalt alloy in a magnetic system. The results of the research allowed us to introduce correction coefficients in the method of calculating the repulsive force in a magnetic system with such magnets, depending on the air gap between of them. It is shown that the repulsive forces of the North poles of permanent magnets differ from the repulsive forces of the South poles. The research was carried out with magnets manufactured by different enterprises. When calculating the repulsive force, the average value of the repulsive force between the North and South poles of magnets is found.

Studies on the surface area of zeolites, as determined by physical adsorption and X-ray crystallography

1968 ◽  
Vol 46 (10) ◽  
pp. 1695-1701 ◽  
Author(s):  
D. J. C. Yates
Keyword(s):  
Surface Area ◽  
Physical Adsorption ◽  
Independent Method ◽  
Linear Portion ◽  
Adsorbed Molecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Surface Areas

The determination of the surface areas of zeolites is discussed. It is shown that it is incorrect to use the multilayer isotherm method of Brunauer, Emmett, and Teller for solids where only little more than one monolayer can be adsorbed, in cavities little larger than the adsorbed molecules. The areas of such materials can, however, be determined from the beginning of the linear portion of their isotherms (point B). In addition, X-ray spectra can provide an independent method of measuring changes in the surface areas of zeolites.

scholarly journals Magnitude-frequency of sea cliff instabilities

2008 ◽  
Vol 8 (5) ◽  
pp. 1161-1171 ◽  
Author(s):  
F. M. S. F. Marques
Keyword(s):  
Hazard Assessment ◽  
Spatial Scales ◽  
Power Laws ◽  
Inverse Power ◽  
Frequency Relationship ◽  
Relationship Of ◽  
Sea Cliff ◽  
Hazard Components ◽  
Cliff Retreat ◽  
Horizontal Area

Abstract. The magnitude-frequency relationship of sea cliff failures in strong, low retreat rate cliffs, was studied using systematic historical inventories carried out in the coasts of Portugal and Morocco, in different geological and geomorphological settings, covering a wide size scale, from small to comparatively large rockslides, topples and rockfalls, at different time and spatial scales. The magnitude-frequency expressed in terms of volume displaced and of horizontal area lost at the cliff top showed good fit by inverse power laws of the type p=a.x−b, with a values from 0.2 to 0.3, and exponents b close to 1.0, similar to those proposed for rockfall inventories. The proposed power laws address the magnitude-frequency for sea cliff failures, which is an important component of hazard assessment, to be completed with adequate models for space and time hazard components. Maximum local retreat at the cliff top provided acceptable fitting to inverse power laws only for failures wider than 2m, with a = 4.0, and exponent b = 2.3, which may be useful to assess the cliff retreat hazard for the use of areas located near the cliff top.

Factors Influencing the T-50 Value

1941 ◽  
Vol 14 (2) ◽  
pp. 501-513
Author(s):  
E. R. Gardner
Keyword(s):  
Accurate Method ◽  
Independent Method ◽  
The State ◽  
Routine Test ◽  
Metallic Oxides ◽  
Sulfur Determination ◽  
State Of Affairs ◽  
Sulfur Containing ◽  
Rubber Article

Abstract The paramount importance of producing the correct state of cure in a rubber article is too well known to need further emphasis. In the light of this, statement, the necessity of possessing a convenient and accurate method of assessing the state of cure is obvious. Before the advent of the T-50 test, the state of cure was measured mainly by a determination of the quantity of sulfur combined with the rubber, of stress-strain properties, or of optimum resistance to aging. The determination of combined sulfur has a disadvantage which is immediately apparent; it is laborious. Also, the figure obtained includes the amount of sulfur combined with metallic oxides used as activators, and to get an accurate measure of the quantity of sulfur combined with the rubber, a second analysis must be undertaken. There is yet another disadvantage, namely, that sulfur-containing substances added to the rubber mix interfere with the determination. The determination of tensile strength, modulus, or resistance to aging cannot be regarded as suitable for giving an accurate measure of cure, and are probably best looked on as complementary to the sulfur determination. With this state of affairs existing, it was only to be expected that, on the introduction of an entirely new and independent method of testing the state of cure, far-reaching claims should have been made, and also that the discovery should have been hailed as the elixir for all cure-testing ills. The present work was undertaken with a view to testing the validity of the claims put forward and to investigating, prior to the introduction of the T-50 as a routine test, the effect of variables likely to be encountered.

scholarly journals Tuning the Re/Os Clock: Stellar-Neutron Cross Sections

2009 ◽  
Vol 26 (3) ◽  
pp. 250-254 ◽  
Author(s):  
A. Mengoni ◽  
M. Mosconi ◽  
K. Fujii ◽  
F. Käppeler ◽  
Keyword(s):  
Cross Sections ◽  
Reaction Rates ◽  
Experimental Information ◽  
Nuclear Model ◽  
Time Duration ◽  
Model Calculations ◽  
Neutron Time ◽  
Neutron Cross Sections ◽  
Capture Cross Sections

AbstractThe neutron-capture cross sections of 186,187Os have been recently measured at the CERN neutron time-of-flight facility n_TOF for an improved evaluation of the Re/Os cosmo-chronometer. This experimental information was complemented by nuclear model calculations for obtaining the proper astrophysical reaction rates at s-process temperatures. The calculated results and their implications for the determination of the time-duration of nucleosynthesis during galactic chemical evolution is discussed.

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