bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and Comparison of Two X-Ray Methods for Determining the Crystallinity of Cotton Cellulose
Authors: Wakelin James H. , Virgin Hester S. , Crystal Eugene 
Published: April 2005

Two x-ray methods have been developed for determining the crystallinity of cellulose using a Geiger counter spectrometer. The two methods were applied to six native cotton varieties, to a cross-bred variety, and to two cottons chemically modified with ethylamine. The x-ray scattering curves for each of the nine samples were compared with those from a highly crystalline sample, a cotton hydrolyzed in HCl, and an amorphous cotton sample to provide a relative measure of crystallinity, or crystalline index.
With fully corrected data the average crystalline index of the six cotton varieties was found to be 68.3 and 78.7% by the correlation and by integral methods, respectively. The crystalline indices of the remaining samples determined by the correlation and by the integral methods are, respectively, cross-bred cotton (S×P), 54.3 and 77.2%; cotton treated with anhydrous ethylamine, 29.7 and 50.9%; and cotton treated with 75% aqueous ethylamine, 28.3 and 50.3%.
Space Charge Waves in Cylindrical Plasma Columns
Authors: Trivelpiece A. W. , Gould R. W. 
Published: April 2005

When a plasma is of finite transverse cross section, space-charge waves may propagate even in the absence of a drift motion or thermal velocities of the plasma. Some of the properties of these space charge waves have been investigated by regarding the plasma as a dielectric and solving the resulting field equations. The effect of a steady axial magnetic field is considered, but motion of heavy ions and electron temperature effects are neglected. Waves are found to exist at frequencies low compared with the plasma frequency as well as waves with oppositely directed phase and group velocities (backward waves).
Many of the features of these waves have been verified experimentally by measuring phase velocity and attenuation of waves along the positive column of a low pressure mercury arc in an axial magnetic field. Measurements of electron density have been made using these waves and the results are compared with those obtained by other methods. An interesting feature of these measurements, of value in plasma diagnostics, is that they can be made with frequencies which are small compared with the plasma frequency.
Helical Fields
Authors: Poritsky H. 
Published: April 2005

This paper is devoted to a study of helical fields, that is fields which are invariant under screw motions of space which move a certain helix into itself.
Simple, analytic, helically invariant solutions of the Laplace equation are given and combined to describe the electrostatic field of a charged helix, and of the magnetic field of a helical electric current. A flux function ψ is introduced for solenoidal helical vector fields, and differential equations resembling Cauchy-Riemann equations are derived for the potential function φ and the flux function ψ. Certain graphical flux plotting methods are outlined and illustrated, and network analogies are suggested for solving these fields.
Domain Wall Motion and Ferrimagnetic Resonance in a Manganese Ferrite
Authors: Dillon J. F. , Earl H. E. 
Published: April 2005

From a single crystal of manganese ferrite, specimen cores have been cut which are capable of supporting single domain walls. These cores have been proportioned in two ways, one favoring a movable (110) wall, the other favoring a wall system perpendicular to the (110) plane. The basic experiment consists in applying rectangular current pulses to a winding, and observing the rate of change of flux as presented by the voltage in another winding. At low driving fields, the wall, once torn free of the surface, moves through the crystal at a velocity proportional to the applied field less an internal coercive force. At high fields the pulse shapes indicate complex domain structure.
Ferrimagnetic resonance experiments have also been performed on samples cut from the same crystal, and the results of these are given. It is particularly interesting to compare the loss parameter for the equation of motion which we derive from the resonance experiments with that obtained from the wall motion experiment.
Line Widths in Polycrystalline Yttrium Iron Garnet
Authors: Van Uitert L. G. , Swanekamp F. W. , Haszko S. E. 
Published: April 2005

The line widths at the half-power point for ferromagnetic resonance in a number of polycrystalline yttrium iron garnet samples have been measured at 16 kmc.
It has been determined that, starting with mixtures of Y2O3 and Fe2O3, sound parts with small grain size and having line widths as low as 35 to 40 oersteds can be obtained on the iron-rich side of stoichiometry in Y3Fe5O12. However, narrower line widths (∼20 oersteds) in large grained materials are obtained by using less than the stoichiometric amount of iron and firing at temperatures higher than 1450°C. This is due to minimizing the disrupting influences of oxygen loss in iron-rich areas at high temperatures.
Line widths do not appear to be broadened by the addition of small amounts of nickel, cobalt, or manganese to convert excess iron to high resistance forms of spinel in the iron-rich compositions.
Sputtering Yield of Germanium in Rare Gases
Authors: Laegreid N. , Wehner G. , Meckel B. 
Published: April 2005

Sputtering yields of germanium bombarded by Xe+, Kr+, A+, Ne+, and He+-ions under normal incidence at energies up to 400 ev have been determined. Yield vs ion energy curves consist of three parts; (1) a low-energy tail (possibly caused by a process of stepwise sputtering), (2) a region in which yield rises proportionally with ion energy, and above ion velocities of ∼3×106 cm/sec, (3) a region in which the yield rises less than proportionally with ion energy.
The slope in the proportional region is largely determined by the energy transfer factor, η=4m1m2/ (m1+m2)2. Surprisingly, the ``cut in'' energies do not follow V0∼H/η (H=heat of sublimation) but are found to be much lower than expected for the lighter gases. The empirical result, V0∼H(m1)½/η (m1=atomic weight of ion), is not yet understood.
Experimental Method for Developing Minute Flaw Patterns in Glass
Authors: Levengood W. C. 
Published: April 2005

A new chemical etching technique was used to study minute flaw patterns in glass. The etched structure disclosed that the minute defects react to the chemical treatment in a different manner than ordinary fissures. Flaw patterns formed at the tips of slow-moving internal cracks were analogous to dislocation phenomena in crystals.
Oriented and repeating flaw groupings were observed in various types of glass. These patterns are produced above the ``strain point'' and were shown to be influenced by permanently induced stresses and internal homogeneity.
Fracturing by localized stresses created flaw patterns radiating from the point of origin with shapes similar in appearance to shock wave phenomena. The impact breaking strength of glass containers was directly influenced by the number of flaws. The flaw distribution decreased rapidly with decreasing diameter of glass fibers.
Stress Waves and Fracture Surfaces
Authors: Andrews E. H. 
Published: April 2005

Surface markings observed in the brittle fracture of certain frozen rubbers display striking wave-like characteristics. They have been identified as ``Wallner'' lines, caused by the interaction of the fracture front with stress waves emanating from the region of the fracture front itself. These oscillations are possibly caused by the supply of excess energy to the fracture tip.
A value of approximately 1:2 is obtained for the ratio of fracture velocity to wave velocity.
Space Charge in Semiconductors Resulting from Low Level Injection
Authors: Green Milton 
Published: April 2005

A solution of the continuity equations is obtained for the space charge distribution by assuming (1) that deviations from neutrality are small, and (2) that the space charge fields, which are a consequence of the terms containing ▿·E in these equations give rise to pure diffusion and pure ``drift-wave'' terms with time dependent coefficients. It is, for equal numbers of holes and electrons initially injected, e[(p−p0)−(n−n0)]=−τρ∇ lim E·J[1−exp(−t/τρ)], where τρ equals K/4πσ, the relaxation time, J is the total current density including diffusion, as well as drift, and ∇ lim E means that the divergence does not operate on E (the electric field is held constant). In the differentiation ∂n/∂x and ∂p/∂x are considered to be equal, as are ∂2n/∂x2 and ∂2p/∂x2.
Working independently, H. Brooks and W. van Roosbroeck arrived at expressions for both the ambipolar diffusion coefficient and the ``group mobility'' of the drift of a pulse of excess carriers. This theory yields the same results, and, in addition, transient expressions are gotten for each.
Single Crystal Anisotropy and Magnetostriction Constants of Several Ferromagnetic Materials Including Alloys of NiFe, SiFe, AlFe, CoNi, and CoFe
Authors: Hall R. C. 
Published: April 2005

The anisotropy and magnetostriction of single crystals of several ferromagnetic materials have been determined experimentally. The materials include the metals iron and nickel, binary alloys of nickel iron, silicon iron, aluminum iron, cobalt nickel, and cobalt iron, ternary alloys of molybdenum nickel iron, nickel cobalt iron, and molybdenum aluminum iron, and magnetite. The effect of the order-disorder reaction on these properties was measured for several of the alloys.
The present data for the nickel iron and silicon iron systems agree well with recently published values. Ordering generally raises the magnetostriction and lowers the anisotropy of the aluminum iron alloys near the Fe3Al composition. The first anisotropy constant, K1, for the cobalt nickel system as derived from torque curves is similar to old data derived from magnetization curves. However, K1 for cobalt iron (30, 35, and 45% cobalt) appears to be considerably larger than previously reported. In general, the addition of cobalt to nickel and to iron changes the magnetostriction constants (λ100 and λ111) toward large positive values. Thus, λ100 increases to 100×10−6 for 50% cobalt nickel and to 130×10−6 for 45% cobalt iron; λ111 increases to 30×10−6 for 45% cobalt iron but remains approximately constant for the cobalt nickel alloys.
X-Ray Measurement of Microstrains in Germanium Single Crystals
Authors: Hunter L. P. 
Published: April 2005

The high intensity of the anomalously transmitted x-ray beam depends upon the coincidence of the nodal planes of the x-ray wave field with one set of atomic planes within the crystal when the crystal is set for Laue diffraction. If there is any structural defect within the crystal which causes some of the atoms of the crystal to deviate from their normal location in perfect planes, these atoms will no longer be at the nodes of the x-ray wave field and by their absorption they will reduce the transmitted intensity.
The present paper shows how this effect may be employed to measure the amount of microstrain present in nearly perfect germanium crystals. It is found that some apparently dislocation free crystals show a greater degree of crystalline imperfection than crystals with a finite dislocation count.
Paramagnetic Resonance in Electron Irradiated Silicon
Authors: Bemski G. 
Published: April 2005

Electron spin resonance has been observed in n-type silicon irradiated with 0.5-Mev electrons. The particular resonance lines discussed here appear only in pulled crystals which contain about 1018 oxygen atoms per cm3. The lines do not appear in floating zone crystals (&lt;1017 oxygen per cm3). The pattern is anisotropic with respect to the field orientation and can be fitted with a g tensor with components g[100]=2.0029, g[110]=2.0019, g[11̄0]=2.0096.
Hyperfine structure due to interactions with Si29 nuclei is also observed. The hyperfine structure tensor exhibits a [111] symmetry indicating that the electron is not centered on the silicon nucleus with which it is interacting. A model is suggested, consistent with the observed symmetries, according to which vacancies produced during irradiation diffuse to the distorted regions around oxygen atoms.
First Magnetocrystalline Anisotropy Constants of Some Iron-Silicon Alloys
Authors: Arajs Sigurds , Chessin Henry , Miller D. S. 
Published: April 2005

First magnetocrystalline anisotropy constants K1∞ of 3.6, 6.7, 8.8, and 12.4 wt% silicon in iron alloys have been measured at 77°K and 297°K by determining the torque exerted on {100} single-crystal disks in uniform magnetic fields. The following results on disordered alloys have been obtained: Composition (wt%Si)Temperature (∘K)K1∞×103(erg cm−3)3.677430±10297360±106.777290±10297205±108.877245±10297165±1012.477120±529778±5
The measurements of this investigation are compared with the previously known studies. The agreement, where an overlap occurs, is satisfactory.
dc Resistivity in the Nickel and Nickel Zinc Ferrite System
Authors: Van Uitert L. G. 
Published: April 2005

The dependence of the resistivities of nickel and nickel zinc ferrites prepared from high purity reagents upon composition and firing temperature has been studied.
It has been determined that iron deficient nickel zinc ferrites are of much higher resistivity than iron deficient nickel or zinc ferrites.
The iron deficient ferrites prepared, which were fired in oxygen below 1300°C and have Ni:Zn ratios greater than 3:7, show a positive thermoelectric voltage. Other compositions or materials fired above 1300°C have a negative thermoelectric voltage.
The effect of excess iron upon resistivity is dependent upon the presence or absence of zinc at temperatures below 1300°C.
New Form of Molecular Potential Function for Use in Molecular Vibrational Analysis
Authors: Slowinski Emil J. 
Published: April 2005

A molecular potential function which takes simple and direct account of intramolecular strains is proposed. The parameters in the function are the conventional bond-stretching and angle-bending force constants and the strain-free magnitudes of the bond lengths and bond angles.
The function is applied to the analysis of the vibrations of XY2 molecules with C2v symmetry. Calculations based on the zero-order frequencies of H2O and D2O indicate that a three-parameter function is adequate for these molecules. All molecules studied with the function show a moderate attraction between the end atoms of the molecules, resulting in a decrease in the size of the bond angle from the strain-free value. For compounds of the oxygen family with hydrogen the bond angle at zero strain appears to have a constant value equal to 120°.
Absorption Spectrum and Quantum States of the Praseodymium Ion. I. Single Crystals of Praseodymium Chloride
Authors: Sayre Edward V. , Sancier Kenneth M. , Freed Simon 
Published: April 2005

The structure of the polarization spectra exhibited by single crystals of anhydrous praseodymium chloride permitted the assignment of quantum states of the praseodymium ion because of the fact that the symmetry of the crystal fields had previously been determined by x-rays. The crystals which were diluted with isomorphic, colorless lanthanum chloride, were grown from melts.
Observations of transitions over the range from 2200 A to 18 000 A at the temperatures of liquid nitrogen and liquid helium led to the identification of seven upper states as well as the substates into which they were split by the crystal fields. The four lowest substates of the ground state also were characterized. The F triplet was found inverted.
All the transitions were forced electric dipole in nature.
Absorption Spectrum and Quantum States of the Praseodymium Ion. II. Anhydrous Praseodymium Fluoride in Films
Authors: Sayre Edward V. , Freed Simon 
Published: April 2005

The absorption spectra of anhydrous praseodymium fluoride were examined to confirm term designations derived from the spectra of anhydrous praseodymium chloride. In the fluoride, praseodymium ion is at the center of a micro-field of C2V symmetry and in the chloride it is in a field of C3h symmetry. There was complete consistency in the interpretations of the spectra of the two compounds.
A new phenomenon appeared in the spectrum of the fluoride, however. The selection rules prohibiting some of the possible transitions of an ion in a field of C2V symmetry valid at the temperature of liquid nitrogen were lifted at the temperature of liquid helium, where in fact all possible transitions occurred. There is evidence against any gross crystallographic transformation.
It is surmised that the positions of energy minimum for the ions lie slightly off the symmetric positions possibly due to higher order interactions such as occurs in the case of barium titanate.
Dielectric Dispersion of Rochelle Salt in the Microwave Region
Authors: Akao Humio , Sasaki Taizo 
Published: April 2005

The dielectric dispersion of rochelle salt was measured at 3000∼20 000 Mc/sec using a new method. In this method ε′ and ε″ is obtained by measuring the half-power point and the shift of resonant frequency of a rectangular TE01 mode cavity.
These results show that the relaxation frequency of rochelle salt exists in the decimeter wave region.
Theory of Internal Over-All Rotational Interactions. II. Hamiltonian for the Nonrigid Internal Rotor
Authors: Kivelson Daniel 
Published: April 2005

An approximate Hamiltonian for a nonrigid internal rotor has been derived. The potential energy has been expanded in a Taylor's series in the displacement coordinates and in a Fourier series in the angle of internal rotation Θ. The Hamiltonian was transformed by a contact transformation, and a second-order Hamiltonian in which vibrations and rotations have been separated has been obtained. The Hamiltonian consists of terms which constitute the usual rigid internal rotational problem, of centrifugal distortion terms involving both over-all and internal angular momentum, and of terms that arise because of the repulsive nature of the barrier. These repulsive terms enter as a single term, 2JFv(m|1 — cos3Θ|m), in the expression for the rotational transitions of symmetric rotors, where J is the total angular momentum quantum number and m is the pseudo-quantum number for internal rotation. The repulsive constant, Fv, is given by the relation Fv=−Σ12[Bxx(i)+Byy(i)]ai(1),where Bxx(i)+Byy(i) is the derivative of the rigid rotor rotational constant with respect to the ith symmetry coordinate, and ai(1) is one-half the displacement of the equilibrium position of the ith internal coordinate in going from Θ=0 to Θ=π/3.
The dependence of the barrier height upon the vibrational motion has also been studied.
Theory of Internal Over-All Rotational Interactions. III. Nonrigid Asymmetric Rotors
Authors: Kivelson Daniel 
Published: April 2005

The theory of the interactions of hindered internal rotation with over-all rotations is extended to include nonrigid asymmetric rotors. The interdependence of hindered internal rotation and vibrations and their effect upon the vibrational energy levels is considered. The theory is developed analogously to the theory developed for symmetric rotors in a previous paper. An approximate over-all internal rotational wave function of the form 1/(2π)½ exp[i(PzIz2/Iz —τ)]φr is discussed, where φr is the wave function that diagonalizes the rigid rotor Hamiltonian and τ is an integer.
While the general energy relation involves too many parameters to compute or to fit empirically, certain special cases are discussed. In particular for the 000→101 transition of the CH3NO2 type of molecule one has ν(000→101)=(101|〈H〉R|101)[1+F1(m|1−cos3θ|m)+G2(m|Π2|m)]+2G3(m|Π2|m)+2F2(m|1−cos3θ|m), where (101|〈H〉R|101) is the rigid rotor energy for the 101 level, Θ is the angle of internal rotation, II is the internal angular momentum, m indicates a given internal rotational level, and the F's and G's are constants which can be evaluated from a knowledge of the vibrational characteristics of the molecule and of the forces that constitute the hindering barrier to internal rotation.
Scattering of High Velocity Neutral Particles. VI. Krypton-Krypton
Authors: Amdur I. , Mason E. A. 
Published: April 2005

Total collision cross sections have been measured for krypton atoms with energies between 700 and 2100 ev, scattered in room temperature krypton, to obtain potential energy information for the interaction of two krypton atoms. The potential function may be represented by V(r)=2.55×10−10/r5.42 ergsfor r between 2.42 A and 3.14 A.
The present potential appears to be consistent with potentials, valid at larger separation distances, which have been derived from measurements of gaseous compressibility, transport, and crystal properties, within the limits of uncertainty of these larger distances potentials.
Statistical Computation of Mean Dimensions of Macromolecules. III
Authors: Wall F. T. , Hiller L. A. , Atchison W. F. 
Published: April 2005

Random walks subject to the excluded volume effect have been generated by means of a high-speed electronic digital computer for a number of different three-dimensional lattices and for one four-dimensional lattice. In contrast to results obtained for two-dimensional lattices discussed in an earlier article, the present results are compatible with the view that the ratio, 〈rn2〉Av/n, where 〈rn2〉Av is the mean square length of permissible walks of n steps, converges as n→ ∞ for three-dimensional and four-dimensional lattices. This conclusion is obtained through an analysis of an appropriate difference equation employing the methods developed earlier.
Convergence to a limiting value of the critical ratio mentioned above appears relatively rapid for the four-dimensional lattice investigated. Possible convergence for the three-dimensional lattices that have been investigated to date appears to be very slow. Thus, it appears that the limiting behavior will not be approached experimentally for values of n within the usual range of the degrees of polymerization of real polymer molecules.
Shape of the Coexistence Curve in the Perfluoromethylcyclohexane-Carbon Tetrachloride System
Authors: Gopal Ram , Rice O. K. 
Published: April 2005

Transition temperatures for the transition from the one-phase to the two-phase condition have been observed for the perfluoromethylcyclohexane-carbon tetrachloride system. It is found that (Tc—T+0.001°)⅓ (where Tc, which is equal to 28.623°, is the observed critical temperature) is a linear function of the molecular fraction of carbon tetrachloride. As is indicated by the form of this function there appears to be a flat horizontal portion at the top of the coexistence curve, which extends from 0.5375 to 0.5625 volume fraction CCl4. It involves such a small temperature range as to be almost unobservable and the flat top is much less marked than in the cyclohexane-aniline system.
The melting point of perfluoromethylcyclohexane has been found to be —41.72°C.