bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-Range Interaction in Two-Electron Systems
Authors: Carr W. J. , Ashkin M.
Published: January 2005

The methods of Gor'kov and Pitayevski and Herring and Flicker for calculating the exact exchange interaction in a well-separated two-electron system have been examined in more detail, and attention has been given to the wavefunction.

An attempt has been made to apply the method to a case approximating two electrons in the electron gas problem as well as to the hydrogen molecule.

In the case of hydrogenic systems, it is concluded that the usual Heitler-London method is satisfactory for giving the exchange energy since there is a natural ``cutoff'' separation beyond which the exchange is of little interest, and up to this separation no important difference exists between the exact and the Heitler-London results. The ``cutoff'' is reached when the purely magnetic energy becomes equal to the exchange. However, differences between the exact and the Heitler-London wavefunctions can be significant, and an approximate form is discussed which may be of value in variational calculations for more involved systems.
Intermolecular Potential-Energy Function for Simple Molecules
Authors: Dymond J. H. , Rigby M. , Smith E. B.
Published: January 2005

A new empirical intermolecular potential-energy function with two adjustable parameters is developed. When due allowance is made for nonpairwise additivity of intermolecular energy this function is capable of interpreting both the second and third virial coefficients and the solid-state properties of simple substances.
Thermodynamic Properties of Amorphous and Crystalline Ethylene Glycol-Water Solution
Authors: Milnes M. V. , Zanella F. M.
Published: January 2005

Using a precision adiabatic calorimeter, the heat capacity of a sample of 62.5-wt % ethylene glycol-water solution was accurately measured from −188° to 25°C. It was found that the solution readily supercools with a glass transition temperature of −131°C. The change in heat capacity at the glass transition temperature agrees with the theoretical value based on the hole theory of liquids. The change in heat capacity computed from these data was found to be 0.223 cal deg−1·g−1 or 3.69 cal deg−1·``mole of beads''−1.
Deuterium and Tritium Saturated-Liquid PVT According to the Quantum-Mechanical Principle of Corresponding States
Authors: Rogers John D. , Brickwedde F. G.
Published: January 2005

The quantum-mechanical principle of corresponding states was used to determine the saturated-liquid PVT of D2 and T2 up to the critical points. The critical-point temperature of T2 was determined to be 40.0°K and the critical-point density to be 0.109 g/cm3.
Some Excited States of the Helium Molecule. I. The Lowest 1Σu+ and 3Σg+ States and the First Excited 1Σg+ States
Authors: Browne J. C.
Published: January 2005

We report here some theoretical potential curves for the 1Σu+(2s, 1S0), 1Σg+(2s, 1S0), 1Σg+(2p0, 1S0), 3Σg+(2s, 3S1), and 3Σg+(2p0, 3S1) states of the helium molecule. We find, using a two-term wavefunction with a mixed basis of Slater-type orbitals and elliptic orbitals, that the 1Σu+ potential curve has a maximum of about 0.174 eV at R=5.0a0 and a minimum at R=2.07a0 with a rationalized binding energy, EB=E (calc., Re) − E (calc., R=∞) of EB=1.9 eV. We find, in agreement with the recent suggestions of R. S. Mulliken, that the lowest bound state of the helium molecule of symmetry 3Σg+ and the first bound excited state of symmetry 1Σg+ arise from the interactions He(1S0, 1s2)+He(3S0, 1s2s), 3Σg+(2s, 3S1), and He(1S0, 1s2)+He(1S0, 1s2s), 1Σg+(2s, 1S0), respectively. The 1Σg+(2s, 1S0) and 3Σg+(2s, 3S1) states were also found to have maxima in their computed potential curves. The computed maxima are: 1Σg+≈0.7 eV, R=4.5a0; 3Σg+≈0.8 eV, R=3.75a0.
Numerical Calculation of Potential-Energy Curves by the Rydberg-Klein-Rees Method
Authors: Zeleznik Frank J.
Published: January 2005

A technique is presented for the numerical evaluation of the integrals occurring in the Rydberg-Klein-Rees method of calculating potential-energy curves.
Radial Distribution Functions for Mixtures of Hard Spheres
Authors: Throop Gerald J. , Bearman Richard J.
Published: January 2005

The exact solution of the Percus-Yevick equation for the radial distribution functions of a mixture of hard spheres found by Lebowitz is evaluated numerically. The results are discussed.
Raman Spectrum of Benzene Crystal
Authors: Ito Mitsuo
Published: January 2005

The Raman spectrum of the benzene crystal has been observed at 77° and 195°K. All the gas-phase-allowed fundamentals have been found. Only the Raman band ν7(e2g) has been found to split into two bands in the crystal, while all the other fundamentals have shown no splitting due to the crystal field. The splitting of ν7(e2g) indicates invalidity of the dipole-dipole coupling model for the benzene crystal. The interpretation by Mair and Hornig about the doublet structure of several infrared combination bands involving ν10(e1g) has been revised from the result of the direct observation of the Raman fundamental ν10(e1g). A weak Raman band at 1012 cm−1 is difficult to give a reasonable interpretation. It has been suggested that it is due to the fundamental ν12(b1u) appearing in the Raman spectrum in violation of the selection rule.
Calculation of the Viscosity of Ammonia at Elevated Pressures
Authors: Gupta A. Das , Barua A. K.
Published: January 2005

The apparently anomalous negative pressure coefficient of viscosity of ammonia as observed in the recent experiment of Iwasaki, Kestin, and Nagashima has been explained by considering dimerization. The results confirm the suggestion put forward by Barua and Das Gupta for explaining the pressure dependence of the viscosity of superheated steam.
Classical Equation of State for Molecules Interacting with Purely Repulsive Potentials
Authors: Hecht Charles E.
Published: January 2005

The virial development of the equation of state for molecules interacting with purely repulsive potentials is studied. The total number of positive terms contributing to any such virial coefficient is proven to exceed the total number of negative terms. Nevertheless, the virial coefficients are not necessarily all positive. From the fact that the asymptotic (finite system) equation of state for hard spheres and hard parallel cubes approaches the free volume form as the density increases to that of close packing, a reasonable asymptotic form for the virial coefficients Bl is deduced for l large. This form shows an unusual volume dependence. An isotherm for the parallel hard-cube gas is obtained which exhibits a van der Waals-like loop indicative of a first-order phase transition with a density change of roughly 12% across it. The entropy change in the transition is small and not in accord with the elementary account of a communal entropy change in the transition of a gas to a solid.
Investigation of Triplet-State Energy Transfer in Organic Single Crystals by Magnetic Resonance Methods
Authors: Hirota Noboru , Hutchison Clyde A.
Published: January 2005

The transfer of triplet-state energy from phenanthrene-d10 molecules to naphthalene molecules in a single crystal of diphenyl has been investigated by electron magnetic resonance methods. The decay rates of the magnetic resonance signals of triplet-state phenanthrene-d10 and naphthalene, both when they occurred as single solutes and also when they occurred together in diphenyl single crystals, have been studied over a wide range of temperatures. A number of processes leading to a satisfactory kinetic model have been considered and numerical values of concentrations of postulated species and of rates have been determined. Predictions concerning delayed optical emission, made on the basis of the proposed kinetic model, have been experimentally confirmed.
Superparamagnetism in the Low-Temperature Limit of Ising Models
Authors: Edelstein A. S.
Published: January 2005

It is shown that at low magnetic fields the low-temperature limit of a linear antiferromagnetic system containing a small concentration of frozen-in ferromagnetically coupled impurities is an analog to a random walk with restricted reversals. This results in the equivalence of the average chain to a single free spin of magnitude q½/2, where q is the number of impurities in the chain. The high field magnetization probably increases in steps of increasing height and width in the region in which the magnetic field overcomes the impurity exchange coupling. Possible generalizations to more dimensions and intermediate coupling are discussed. The frozen-in impurities and a gas of impurities may serve, respectively, as lower and upper bounds on a broader class of problems. An experiment for measuring the correlations 〈σ1, σn〉 between distant spins is suggested. The lack of field saturation and large decrease in susceptibility of certain organic free radicals is discussed.
Nuclear Quadrupole Interactions in Alkali Halide Molecules
Authors: Das T. P. , Karplus M.
Published: January 2005

The field gradients at the positive- and negative-ion nuclei in alkali halide molecules are analyzed taking account of overlaps between the atomic orbitals for the electrons within the ions and covalent binding through the transfer of electrons from the negative to positive ions. Explicit numerical calculations were performed for the case of the KCl molecule. It is shown that the inclusion of overlap effects, in addition to pure ionic contributions considered earlier, alters the field gradient in the right direction to improve the agreement with the observed field gradient at the chlorine nucleus. Charge-transfer covalency, on the other hand, increases the discrepancy with experiment. The field gradient at the positive-ion nucleus is also affected quite significantly by the inclusion of overlap effects.
Photosensitized Ionization of Alkali-Metal Vapors
Authors: Lee Yuan-tseh , Mahan Bruce H.
Published: January 2005

The vapors of potassium, rubidium, and cesium have been photoionized with light absorbed in the discrete region of the atomic spectrum. The energy threshold for the ionization process has been determined and the ions produced identified by mobility measurements. The data give lower limits for the dissociation energies of K2+, Rb2+, and Cs2+. Each of these molecular ions has a bond energy approximately 50% greater than that of the corresponding neutral molecule. In addition, lower limits for the electron affinities of the alkali atoms and approximate values for the mobilities of Rb+ and Rb2+ in rubidium vapor are given.
Gauge Invariance of the Hartree-Fock Approximation
Authors: Epstein Saul T.
Published: January 2005

(i) Gauge invariance in the presence of nonlocal potentials is reviewed. It is shown that the uncoupled Hartree-Fock method is not gauge invariant. (ii) Gauge invariance of variational calculations is reviewed and it is shown that the coupled Hartree-Fock approximation is gauge invariant. (iii) A procedure for choosing a best gauge is suggested and in a special case is shown to reduce to a method recently proposed by Karplus and Kolker.
Electron Spin Resonance in Gamma-Irradiated Single Crystals of Hydroxylated Organic Compounds
Authors: Rao M. Jagannadha , Anderson Roy S.
Published: January 2005

Free radicals produced by gamma irradiation in the single crystals of four hydroxylated organic compounds, monoammonium malate, monoammonium malate monohydrate, ammonium tartrate, and potassium tartrate, have been studied using the methods of electron spin resonance. In all the four molecules, stably trapped radicals were found to be the result of the splitting of a C–H bond adjacent to both the hydroxyl and carboxyl groups. The isotropic parts of the hyperfine couplings of the two methylene protons in monoammonium malate are 8.9 and 34.3 G. These values in the monohydrate are 14.7 and 34.1 G. The isotropic part of the hydroxyl proton hyperfine coupling in the monohydrate is 2.3 G. Strong spin-flip transitions, giving rise to satellite lines having an intensity up to 40% of the main lines for certain orientations of the crystal in the magnetic field, were observed in monoammonium malate and its monohydrate. The proton responsible for these spin-flip transitions was found to be the hydroxyl proton. The isotropic part of the C–H proton hyperfine coupling in both ammonium and potassium tartrates is 2.1 G.
Far-Infrared Spectrum of Tetrahydrofuran: Spectroscopic Evidence for Pseudorotation
Authors: Lafferty W. J. , Robinson D. W. , Louis R. V. St. , Russell J. W. , Strauss H. L.
Published: January 2005

The infrared spectra of tetrahydrofuran and tetrahydrofuran-d8 are reported between the limits 10 and 300 cm−1. The rather complex spectrum obtained for this molecule is interpreted in terms of the theory of pseudorotation of a puckered ring. The spectroscopically derived value of the parameter mq02 is (8.56±0.13)×10−40 g·cm2 for the ground, v=0, radial state and (8.48±0.15)×10−40 g·cm2 for the excited, v=1, radial state.
Work-Function Studies on the N2-W System
Authors: Hayes F. H. , Hill M. P. , Lecchini S. M. A. , Pethica B. A.
Published: January 2005

Work-function measurements for the nitrogen-tungsten system have been carried out on a polycrystalline ribbon using space-charge-limited and retarding-field diodes. The theoretical limitations of the two techniques are discussed and the controversy concerning the sign of the work-function change examined.
Three-Dimensional Second Virial Coefficient in Physical Adsorption
Authors: Krizan John E.
Published: January 2005

Expressions are obtained for the three-dimensional second virial coefficient in physical adsorption for a system in which the adsorbed particles interact via Lennard-Jones forces plus the three-body force derived by Sinanoğlu and Pitzer. Using these expressions one can investigate the relative importance of the three-dimensional effect of the three-body force. For the particular system of argon on carbon black it is found that the two-dimensional approximation is very good.
Molecular Force Field and Centrifugal Distortion Constants of Nitrosyl Fluoride
Authors: Cook R. L.
Published: January 2005

The microwave spectrum of nitrosyl fluoride, NOF, has been reinvestigated in the microwave region and extended into the millimeter wave region. Some 80 transitions, consisting of both ``a''- and ``b''-type transitions, have been measured and assigned. These data provide the information required for a centrifugal distortion analysis which yields the following ground-state rotational parameters (megacycles per second): A=95 189.77,B=11 844.12,C=10 508.31,τxxxx=−0.099630,τzzzz=−15.586926,τxxzz=0.418629,τxzxz=−0.289581,HJK=2.339×10−6andHKJ=−4.946×10−5.

Combination of infrared data and microwave data yields the following quadratic potential constants millidynes per angstron, fr1=2.09,  fr2=15.08,  fα/d2=1.08,  fr1r2=1.85,  fr1α/d=0.17. Here fr1 and fr2 are the N-F and N-O bond force constants, respectively, and fα is the bond-bending force constant.
Effects of Pressure on Fluorescence and Intersystem Crossing in Benzene Vapor
Authors: Kistiakowsky G. B. , Parmenter C. S.
Published: January 2005

Relative quantum yields of fluorescence have been measured from benzene vapor excited by the 2537-Å mercury line and at total pressures sufficiently low that the lifetime of the fluorescing 1B2u state was much shorter than the interval between collisions. At 84°, the yield and intensity distribution of emission are invariant over benzene pressures from 0.0055 to 0.183 Torr and are not affected by addition of cyclohexane at pressures up to 0.27 Torr. Resonance emission is observed in this pressure region. The yield begins to decrease (and the character of the emission spectrum to change) at a cyclohexane pressure between 0.27 and 0.45 Torr and reaches a limiting value of about 0.6 of that at lowest pressures when cyclohexane pressure is above 10 Torr. The behavior with added CO2 is similar. A benzene sensitized isomerization of cis-butene-2 is observed in the 2537-Å photolysis of benzene-butene mixtures with each gas at 0.05 Torr. Correlation with previous data shows that in the low-pressure region of constant fluorescence yield, collisions do not influence decay of 1B2u benzene molecules, the absolute fluorescence yield is less than unity, and a triplet state is formed. The mechanism of the processes involved is discussed.
On the Electronic States of Crystalline Naphthalene
Authors: Silbey Robert , Jortner Joshua , Vala Martin T. , Rice Stuart A.
Published: January 2005

In this paper, we attempt to correlate the observed electronic spectrum of crystalline naphthalene with the observed spectrum of the free molecule. The normal Frenkel exciton theory is extended to include ion-pair states and the effect of these on the spectrum is taken into account. It is found that the observed spectrum can be accounted for in the present analysis, if the ion-pair state is energetically close to the first excited singlet state of naphthalene.
Closed Form of Infinite Series Used in Some Atomic Integrals Containing r12, r13, and r23
Authors: McKoy Vincent
Published: January 2005

In an excellent scheme recently developed for evaluating the integral ∫ f1(r1)f2(r2)f3(r3)g1(r12)g2(r23)g3(r13)(dv)met in the calculation of correlated atomic wavefunctions, certain functions required in the computational scheme had to be evaluated by an infinite series expansion. As many as 40 terms may be needed in each of the three required infinite summations to get eight significant figures. We give a closed form expression for such functions avoiding all infinite sums. The new result is very compact and avoids the previous difficulty of numerical stability.
Infrared-Band Intensities of Adsorbed Carbon Monoxide
Authors: Seanor D. A. , Amberg C. H.
Published: January 2005

It has been possible in favorable cases to measure the intensities of the infrared bands of CO adsorbed on different ZnO and supported Cu, CuO, and Pt catalyst surfaces. For weak, reversible adsorption at room temperature, giving rise to the bands in the frequency region 2132–2212 cm−1, a unique correlation between intensity and frequency was found which apparently holds for a number of chemically different substrates. Values for both gaseous and dissolved CO fit the correlation reasonably well. A tentative explanation in terms of small perturbations of the dipole moment of CO(g) was advanced. Measurements in the metal carbonyl region were complicated by the formation of multiple-surface species and volatile products [Ni(CO)4].
Canonical Realizations of Lie Symmetry Groups
Authors: Pauri M. , Prosperi G. M.
Published: January 2005

A general theory of the realizations of Lie groups by means of canonical transformations in classical mechanics is given. The problem is the analog to that of the characterization of the projective representations in quantum mechanics considered by Wigner, Bargmann, and others in the case of the Galilei and the Lorentz group. However, no application to particular groups is given in this paper.

It turns out that the generators yτ of the infinitesimal transformations in a canonical realization of a Lie group 𝒢 satisfy relations of the form {yρ, yσ} = cρστyτ + dρσ, where cρστ are the structure constands of 𝒢 and dρσ are constants depending on the particular realization.

It also turns out that any canonical realization of 𝒢 can be reduced to a fundamental typical form by means of a constant canonical transformation in the phase space of the system. This typical form allows one to obtain a complete characterization of all the possible canonical realizations of 𝒢. Once a suitable definition of ``irreducible'' canonical realization is given, a simple classification can be obtained in terms of the values of certain functions of the generators yτ (canonical invariants).

Recalling the correspondence {} → [], formal analogy appears to be achieved with the quantum mechanical case. Even more, a parallel development of the outlined theory in quantum mechanics is of interest in the construction of the invariant operators (even in case of non-semisimple groups) and of complete systems of commuting observables acting within the irreducible representations.
A Necessary Restriction on Correlation Functions Arising from 3- (or More) Particle Systems in One Dimension
Authors: Post H. R.
Published: January 2005

A necessary condition on any pair-correlation function, arising from the symmetry of a system of three or more identical particles, is derived.
Integral Equations in the Theory of Classical Fluids
Authors: Wertheim M. S.
Published: January 2005

Topological analysis of Mayer diagrams is used to obtain generalizations of the Percus-Yevick and convolution hypernetted chain integral equations to systems of equations involving higher correlation functions. Only the higher direct correlation functions appear in the final integral equations. A distinctive feature of the system obtained is the appearance of derivatives with respect to the density. Numerical comparison with exact virial coefficients is made for the standard test potentials of parallel hard squares and cubes.
On the Resonant Frequency of Closed Concentric Lines
Authors: Hansen W. W.
Published: January 2005

A new and more exact method of calculating the resonant frequency of closed concentric line resonators of the type shown in Fig. 1 is developed. The method becomes more accurate as the length of the line becomes small by comparison with a quarter wave-length.
Double Refraction and Change in Length of Certain Plastics
Authors: Farwell H. W.
Published: January 2005

The change in length of a Vinylite plastic under constant load has been measured, as well as for the succeeding recovery. The change in color of the light transmitted through crossed Polaroid plates shows large change in the birefringence. The further study is made with uniform length increments at constant temperature using Mach's method to measure the birefringence, both for stretching and recovery. The data are sufficient to give a measure of the dispersion in birefringence and of a Poisson's ratio of 0.50.
The Viscosity of Pennsylvania Oils at High Pressure
Authors: Dibert R. M. , Dow R. B. , Fink C. E.
Published: January 2005

Viscosity-pressure-temperature data are presented for six Pennsylvania oils which differ in chemical and physical properties at atmospheric pressure. This study is a continuation of one reported previously and employs the same apparatus and experimental method. While the pressure coefficient of viscosity increases in general with molecular weight, the relationship seems to be significant only for fractions of a narrow boiling range from a single oil. The mean temperature coefficient of viscosity, between 100° and 210°F, however, increases with molecular weight at all pressures for all the oil samples.
Cathode-Ray Bunching
Authors: Webster David L.
Published: January 2005

The bunching of cathode rays in the klystron, described in this Journal by R. H. Varian and S. F. Varian, is treated mathematically here, and is found to result in a current having a wave form with sharp peaks and containing strong higher harmonics. In the absence of appreciable ``de-bunching'' by mutual repulsion, the kinematics of the bunching process leads to specifications for an optimum condition of bunching and to the prediction of an ideal efficiency of 58 percent for the conversion of the cathode-ray power into high frequency power. De-bunching becomes important under certain calculated conditions, limiting the amplification factors obtainable in amplifiers without regeneration. It also changes the optimum conditions for oscillators and reduces their efficiencies by calculable amounts. The power required in the buncher is relatively very small and depends on the buncher voltage almost like that of an additional ohmic resistance.
Bactericidal Effects of Ultraviolet Radiation Produced by Low Pressure Mercury Vapor Lamps
Authors: Koller L. R.
Published: January 2005

The killing effect of 2537A radiation has been studied, both for bacteria suspended in air and bacteria and molds on surfaces. A 15-watt sterilizing lamp (giving 25 μw/cm of 2537A radiation at 1 meter from the lamp) will kill 97–99 percent of B. Coli suspended in air at a distance of 24 inches in 10 seconds. Accordingly in an air duct a 15-watt lamp can sterilize approximately 200 cu. ft. of air per minute. A 15-watt sterilizing lamp will kill B. Coli on the surface of agar at a distance of 10″ in 20 seconds. The Bunsen Roscoe reciprocity law applies to the killing of bacteria by ultraviolet radiation between the intensities of 2000 μw/cm2 and 1.3 μw/cm2. The lethal dose of 2537A radiation for B. Coli on agar is 6600 μw sec./cm2. For practical purposes the effect of temperature may be neglected. A film of grease is very effective in shielding bacteria from radiation. The lethal dose of 2537A radiation for black mold spores is about 45 times that for B. Coli. The reciprocity law applies. The sensitivity of mold spores decreases with increasing wave-length and is negligible for 3650A. Low pressure lamps in ultraviolet transmitting glass produce concentrations of ozone of the order of 0.1 part per million. From these experiments it may be concluded that low pressure mercury vapor lamps when used under the proper conditions are very powerful bactericidal agents if the bacteria are directly exposed to the radiation, but that the effectiveness is greatly reduced by even such slight shielding as is offered by a film of grease.
Energy Measurements of Reigniting A.C. Arcs
Authors: Eskin S. G.
Published: January 2005

An oscillographic study of arcs formed between silver contacts in the rupturing of 120-volt a.c. circuits containing resistive loads shows that reignition of the arc occurs at low speeds of contact separation. Data have been obtained by means of a ballistic wattmeter showing the effect of current and line voltage on arc energy for silver contacts opening at speeds from 0.024 to 16.7 inches per second. In the low speed range reignition is more prevalent at 225 volts than at 115 volts, and restriking of the arc occurs at higher speeds for higher currents. The formation of an arc in reigniting cycles is believed to be due to field emission of electrons, an average field of 0.30×106 volts/cm being found for all cases of reignition observed. Reignition occurred at potentials as low as 72 volts and the intermediate glow discharge normally observed in the interruption of inductive circuits did not appear.
The Rate of Plastic Deformation in Lead Under Compression
Authors: Lyons W. James
Published: January 2005

It is shown that the velocities of plastic deformation, deduced from previous experimental data on lead cylinders, are in satisfactory accord with the relation v=a exp (bP),where a and b are constants, and P is the prevailing pressure. Integration of this equation leads to the following expression for deformation as a time-function: ε=1+(1/bP0) ln (abP0t+C),where P0 is initial pressure and C is a constant of integration. Means for evaluating C are given. This equation, requiring adjustments in only a, is found to represent very well the observed relations between deformation and compression-time for four different initial pressures. It is concluded that plastic deformation in lead is governed principally by the exponential law for velocity.
Photographs of Unusual Discharges Occurring During Thunderstorms
Authors: Holzer R. E. , Workman E. J.
Published: January 2005

The known photographs of an unusual type of discharge occurring in intense thunderstorm fields principally near ground objects are described and discussed. A possible explanation of the discharges is suggested.
The Electrostatic Field Produced by a Point Charge in the Axis of a Cylinder
Authors: Weber Ernst
Published: January 2005

The general solution of the field distribution produced by a point charge at rest in the axis of a metallic cylinder is derived, and a simple approximation is given for the field strength on the surface of the cylinder.
A Method for Measuring the Rheological Properties of Materials of Great Consistency Such as Asphalts
Authors: Thelen Edmund
Published: January 2005

It has been found that when an ASTM penetrometer needle is allowed to sink into a material such as asphalt for a series of successive time intervals, the rate of flow varies linearly with the shearing stress as calculated from these equations: a=7.854×10−5(Pf−Pi)t,    b=0.098×104 W0.001571(Pf+Pi)−0.0521,when a =rate of flow in cm3/sec.,

b =shearing stress in dynes/cm2,

Pf =final penetration during interval t, in decimillimeters,

Pi =initial penetration during interval t, in decimms.,

t =time interval in seconds,

W =weight of needle and instrument head in grams.

The first penetration in hard materials and the first several penetrations in soft materials give erratic data; otherwise no systematic errors have been observed, and accuracy depends upon the skill of the operator. As expected from plastometric theory and from previous work by other investigators: (1) Results are almost independent of the shearing stress used; (2) The mobility is affected by the shape of the surface of the material at the point of punch, while the yield value is unaffected; (3) Minus log m, which is mathematically equal to log viscosity when f=0, varies linearly with the temperature. (4) Yield values for asphalts from a particular crude stock vary linearly with the percent asphaltene content—the concentration of zero yield value being at 21.8 percent. (5) On aging, an asphalt increases in yield value and decreases in mobility. The author finds that on air-blowing two particular charge stocks, the melting point can be predicted from the mobility at 77 degrees F: m.p.=(−logm−r)/s+77,when r and s are constants characteristic of the charge stock.
Modern Theory of Solids. III
Authors: Seitz Frederick , Johnson R. P.
Published: January 2005

This article, the last of the series, deals with the properties of the solid surface, and with the influence of impurities and flaws on certain volume characteristics. There has been very little theoretical work in these fields on the basis of the modern views. Consequently, a considerable part of what we shall say will be more or less speculative. We present these ideas in the hope that they may be suggestive, and caution the reader against embracing them uncritically.
The Application of Paschen's Law to the Re-Ignition of an Arc
Authors: Cobine J. D. , Power R. Burton
Published: January 2005

An a.c. arc, in order to restrike after passing through current zero, requires a potential considerably higher than the normal burning potential. This re-ignition potential is investigated for short gaps in nitrogen, using pure graphite electrodes with spacings up to two mm and pressures up to 500 cm Hg. The re-ignition potential is found to have two characteristics. One of these characteristics is followed for the arcs in which the cathode spot is maintained by field emission, and the other is followed for the ``thermionic'' arc. Relations are obtained between this re-ignition potential and both the gas pressure and the gap spacing, with the arc current as parameter. These relations may then be combined into a single relation between the reignition potential and the product of the pressure and spacing. This gives a function that is of the same form as the Paschen law for the initial sparking potential of a gap. The constants of this function are dependent on the arc current, the gas in the space, and the constants of the circuit. That the constants of the re-ignition function are not the same as those for the sparking potential law is to be expected from the very dissimilar conditions applying in the space. Extreme purity of electrode materials and of gas, as well as extreme care in obtaining the experimental results, are essential.
Rheological Properties of Asphalts IV Observations Concerning the Anomalous Flow Characteristics of Air-Blown Asphalts
Authors: Coombs C. E. , Traxler R. N.
Published: January 2005

A great many of the asphaltic bitumens used commercially possess anomalous flow properties to some degree. Although all asphalts are probably elastic in some measure, detection and measurement of this property are difficult in the cases of certain bitumens, especially soft ones where the permanent deformation obscures the elastic effects. Data obtained by means of the rotating cylinder type of viscometer at a low shearing stress show the presence in an asphalt of elastic fore- and after-effects. Frequently, when an asphalt is subjected to increasing shearing forces, a ``threshold'' value is reached above which the ``viscosity'' at a particular stress decreases with time until a constant value is obtained. If an asphalt is subjected to a high shearing stress (above the ``threshold'' value) in a rotating cylinder viscometer and the stress is reduced suddenly to a low value, the viscosity will increase gradually even though the asphalt is being worked constantly. Another manifestation of thixotropy is the age-hardening of asphalts. This increase of viscosity with time, which varies greatly with different asphalts, can be overcome by heating or mechanical working. Upon standing, the viscosity again increases with time. Also, it has been found that for many asphalts the ``viscosity'' diminishes with increased shearing stress. The extent of these anomalous flow characteristics is dependent upon the source of material, the method and extent of processing to which it is subjected, and the temperature and rate of shear at which the measurements are made. Using numerous kinds and consistencies of asphalt, correlations of the Bingham-Stephens alternating stress, the falling coaxial cylinder, and the conicylindrical rotation viscometers have been made. Comparisons were made at essentially the same mean shearing stresses in all three instruments for a particular asphalt. Good agreement was found when the asphalts were essentially viscous. Deviations of the results obtained for the three instruments became greater as the anomalous flow properties became more pronounced.
The Viscosity of Raw Rubber
Authors: Smallwood Hugh M.
Published: January 2005

Eyring's reaction rate theory of the viscosity of simple and of non-Newtonian liquids has been outlined. Mooney's data on the rheology of a sample of raw rubber have been shown to be in agreement with Eyring's theory. The data have been discussed from the viewpoint of the theory, and some conclusions have been drawn concerning the probable mechanism of viscous flow in raw rubber.
Notes on the Electrographic Effect
Authors: Schickele Elizabeth , Carr Percy H.
Published: January 2005

A portion of a metal surface was protected by means of a stencil during exposure in air to 100 kilovolt cathode rays. An attempt was then made to ``develop'' an image of the stencil on the metal surface by the action of some chemical or other reagent. Results confirm previous reports that water vapor is helpful if not essential to satisfactory development. On the metals, silver, copper, tin, zinc, lead, brass, and bismuth, the inorganic materials investigated for developing properties were superior to the organic materials tried. The image was not developed directly by electroplating by any method yet tried on any material except carbon. Attempts to produce an image in relief by first developing it in the ordinary way and then electroplating the specimen, failed except when anthraquinone was used as the developer. However, results by this method were uncertain. Cadmium vapor as a developer produces images of low relief.
Condensation and Adsorption of Mercury Vapor
Authors: Mason R. C.
Published: January 2005

The critical temperature of glass surface for condensation of mercury vapor as a function of density of atoms striking the surface has been found. The results indicate a large nucleus composed of many atoms is necessary for condensation to start; the heat of vaporization of an atom from the nucleus is 13.2 kcal. per mole. Some qualitative observations are reported, showing both rapid and slow adsorption of mercury atoms on glass and metal, and a considerable adsorption of mercury ions.
Effect of High Energy Electron Random Motion Upon the Shape of the Magnetron Cut-Off Curve
Authors: Linder E. G.
Published: January 2005

The shape of the cut-off curve is explained on the basis of a component of high energy random motion superimposed on the electron orbital motion (see references). Electron temperatures determined from the cut-off curve shape agree with those determined by probe methods. The possible effects of the random motion on other magnetron characteristics are pointed out.
The Numerical Solution of Laplace's Equation
Authors: Shortley G. H. , Weller R.
Published: January 2005

This paper considers in detail numerical methods of solving Laplace's equation in an arbitrary two-dimensional region with given boundary values. The methods involve the solution of approximating difference equations by iterative procedures. Modifications of the standard Liebmann procedure are developed which lead to a great increase in the convenience and rapidity of obtaining such a numerical solution. These modifications involve the use of formulas which simultaneously improve a block of points in place of a single point; methods of operating on the differences of trial functions in place of the functions themselves; and also a method of extrapolating to the final solution of the difference equations. The theory underlying these procedures is considered in detail by a new method which involves the expansion of the error and difference functions in terms of eigenfunctions. This permits definite comparison of rates of convergence of various procedures. The techniques of handling practical problems are considered in detail.
Studies in Lubrication II. Experimental Friction Coefficients for Thick Film Lubrication of Complete Journal Bearings
Authors: Morgan F. , Muskat M.
Published: January 2005

A straight line which, when extended, passes through the origin of coordinates is obtained when the coefficient of friction for a full journal bearing operating in the thick film region is plotted against μN/P, where μ is the lubricant viscosity, N the journal speed, and P the bearing load per unit of projected area. At higher speeds, when the film temperature around the bearing is not reasonably uniform, large deviations from this line are found. An increase of friction, which qualitatively confirms the theory developed in part I of this series, is observed when the strength of the source of lubricant is increased.
Electromagnetic Waves in Elliptic Hollow Pipes of Metal
Authors: Chu Lan Jen
Published: January 2005

A theoretical study of the transmission of electromagnetic waves in hollow conducting pipes of elliptic cross section, including field configurations, critical frequencies, velocities of propagation, and attenuations for the six lowest order waves. The pipe of circular cross section is treated as a special case, and the stability of waves in it for small deformation of the cross section is discussed.
Characteristics of the Glow to Arc Transition in Mercury Vapor
Authors: Maxfield Frederick A. , Fredendall Gordon L.
Published: January 2005

The probability of the transition from glow discharge to arc discharge at graphite electrodes has been investigated under carefully controlled cathode conditions. The transition probability was found to increase in an approximately linear fashion with an increase in cathode current density and glow voltage. The curve of transition probability as a function of cathode temperature was found to have a distinct maximum at a temperature of about 400° or 450°C. The probability of the transition occurring at temperatures 50° lower or higher was not more than about one-fourth the maximum. It was also found that the frequency with which the glow to arc transitions occurred depended greatly on the previous history of the discharge and the amount of high voltage positive ion bombardment experienced by the cathode under test. A possible explanation of these results has been based on the hypothesis that it is never possible to de-gas completely the cathode electrode even after prolonged operation in a high voltage discharge. It has been shown that the nonuniform emission of this gas from the cathode in the form of bursts from minute patches can lead to a greatly increased probability for transition from glow to arc.
SOME THEORETICAL ASPECTS OF THE BIOLOGICAL APPLICATIONS OF PHYSICS OF DISPERSE SYSTEMS
Authors: Rashevsky N.
Published: January 2005

A review of the author's recent theoretical work on the properties of small liquid drops and more generally of systems with very large specific surface, is given. When such a system interacts chemically with the surrounding, in such a way, that the mass of the substances, of which the system is constituted, slowly increases, the system will possess, under very general conditions, properties remarkably similar to those found in living organisms. Thus it is found that such a system may possess a positive rate of growth, when its size exceeds a certain critical one. Below this critical size the rate of growth is negative. Such a system therefore can never be formed spontaneously, although all substances necessary for its formation may be present. Under certain very general conditions such a system will, under the influence of osmotic and other forces, divide into two halves, when reaching a certain size, each half again growing and dividing, and so forth. In many cases the system will possess a very definite geometrical form, which will tend to be restored, when the system is deformed by some external disturbance.
A VOLTAGE SELECTIVE NONLINEAR BRIDGE
Authors: Suits Chauncey Guy
Published: January 2005

The important property of the simple series resonance circuit employing resistance, capacitance and an iron core reactor arranged to saturate is the abrupt increase in current at a certain critical voltage. This phenomenon is identified as a quasi-resonant condition, and is compared to resonance in linear circuits. An experimental study is made of a nonlinear bridge circuit comprising two branches of the above type. This bridge is voltage selective in such a manner that the load is only energized thru a certain range (of the supply voltage), which may be small. The variation of bridge output voltage (effective) with bridge supply voltage may be critical. In one case it is observed that 1/100 percent change in supply voltage changes the output (load) voltage by 100 percent. The properties of the bridge circuit are applied to the problem of voltage selective relays which permit the control of many circuits by means of a two wire system. For a bridge comprising identical capacitance and inductance units, but dissimilar resistance, a constant voltage characteristic is noted.
STUDIES WITH AN IONIZATION GAUGE
Authors: Reynolds Neil B.
Published: January 2005

An ionization gauge of the type described by Found and Dushman was calibrated for helium, neon, nitrogen, argon and mercury. The results obtained have been compared with those derived by means of a graphical integration based on the probability of ionization of different gases as a function of electron velocity. The agreement is very satisfactory. The present results indicate that the purely empirical relation between sensitivity and ``molecular number'' (total number of electrons per molecule), reported in the earlier paper, is not generally valid.
RELATION OF LONG LINE CURRENTS TO SOIL CORROSION
Authors: Gill Stanely , Rogers W. F.
Published: January 2005

``Stray currents'' from street electric railways and the like give rise to rapid corrosion of buried pipe lines. A type of currents similar to ``stray currents,'' but which occur at long distances from any possible external source of electric current, has been found on pipe lines. These currents are known as ``long line currents'' and are supposed to originate between the soil and the pipe. They frequently follow the pipe for miles without any change in amperage. To determine possible influence of these currents upon corrosion, measurements of their value were made on an 8-inch oil line upon which much corrosion trouble had been experienced. The line was removed from the ground and the extent of corrosion determined by inspection. Electrical resistivities of numerous samples of soil were determined.

From the data obtained, the following conclusions are drawn:

1. Discharge or accumulation of electric currents of the class which have been termed ``long line currents'' is, in general, without influence upon corrosion of buried pipe lines.

2. Electrical resistivity of soil correlates to a certain extent with corrosion of buried pipe; the relationship is not sufficiently consistent to be of practical value.

3. There is no consistent relationship between soil resistivity and the accumulation or discharge of ``long line currents.''
THIXOTROPY OF LITHARGE AND GLYCERINE
Authors: Karrer E. , Wasserman P.
Published: January 2005

Thixotropy may be defined as change in viscosity; or as change in the hardness of the solid state, after mechanical agitation. Rate of hardening decreases with increase of glycerine (critical point near 32 percent). Rate of hardening increases with rise of temperature. Water accelerates rate of hardening. Acids increase, bases decrease rate of hardening in general. Samples of litharge and of glycerine vary greatly because of differences in particle size, in composition, and particularly amount of moisture.
A NEW INSTRUMENT FOR MEASURING VERY SMALL DIFFERENCES IN GRAVITY
Authors: Hartley Kenneth
Published: January 2005

Description of a new portable instrument for measuring relative values of gravity to within two or three parts in ten million, specially designed for geophysical exploration. The principles of the design are analysed and the methods for eliminating effects of elastic hysteresis, temperature changes, variations in barometric pressure, etc., are discussed. Also effects of initial stresses in materials, defects in alignment of locking mechanism, inaccurate leveling, etc. These difficulties are serious but seem to have been overcome. Results of preliminary field measurements near Houston, Texas, are presented and some comparison between the type of information given by this instrument and by the torsion balance.
ON THE CORRELATION OF ISOGEOTHERMAL SURFACES WITH THE ROCK STRATA
Authors: Van Orstrand C. E.
Published: January 2005

An instance of regional variation in Oklahoma and two cases of local variation, one at Long Beach, California, and the other at Salt Creek, Wyoming, have been selected for consideration from a large number of geothermal surveys conducted during the past few years by the U. S. Geological Survey and the American Petroleum Institute. The causes of local and regional variations are unknown. Possible explanations such as radioactivity, proximity to crystalline rocks, and transfer of heat along the strata are given careful consideration in attempting to explain the observed relations between the strata and the isogeothermal surfaces.
GEOTHERMAL GRADIENT DETERMINATIONS IN THE LAKE SUPERIOR COPPER MINES
Authors: Ingersoll L. R.
Published: January 2005

The Michigan College of Mining and Technology, in cooperation with the Calumet and Hecla Copper Company and the author, is carrying out a program of temperature measurements in the deep copper mines of Northern Michigan, extending the previous work of Agassiz and others. Temperatures are measured with mercury thermometers mounted in bakelite tubes, placed in drill holes in mine workings where the rock has been freshly exposed, special attention being given the effects of drilling, blasting, and other heat conduction considerations. Present results give as the average gradient from the surface to 5679 feet below (temp. 95.3°F), 1°F in 108.5 feet (0.0168°C/meter). The gradient is more nearly uniform than has sometimes been supposed. A preliminary attempt has been made at calculating the previous ``thermal history'' of this region. Diffusivity of specimens of the rock measures 0.0075 c.g.s., and on this basis calculations of theoretical temperature-depth curves have been made for 25 different assumptions of previous temperature conditions, and compared with the actual curve. Results as yet are inconclusive but indicate that at least 30,000 years have elapsed since the last glacial epoch, a longer period than usually assumed.