bluuebunny/crossref_metadata_2025 huggingface dataset:
Endurance exercise training restores atrophy-induced decreases of myogenic response and ionic currents in rat skeletal muscle artery
Authors: Yin Ming Zhe , Kim Hae Jin , Suh Eun Yeong , Zhang Yin Hua , Yoo Hae Young , Kim Sung Joon
Published: March 2019

Atrophic limbs exhibit decreased blood flow and histological changes in the arteries perfusing muscles. However, the effect of atrophy on vascular smooth muscle function is poorly understood. Here, we investigated the effect of unilateral sciatic denervation on the myogenic response (MR) and the ionic currents in deep femoral artery (DFA) smooth muscles from Sprague-Dawley rats. Because denervated rats were capable of treadmill exercise (20 m/min, 30 min, 3 times/wk), the impact of exercise training on these effects was also assessed. Skeletal arteries were harvested 3 or 5 wk after surgery. Then skeletal arteries or myocytes were subjected to video analysis of pressurized artery, myography, whole-cell patch clamp, and real-time quantitative PCR to determine the effect of hindlimb paralysis in the presence/absence of exercise training on MR, contractility, ionic currents, and channel transcription, respectively. In sedentary rats, atrophy was associated with loss of MR in the DFA at 5 wk. The contralateral DFA had a normal MR. At 5 wk after surgery, DFA myocytes from the atrophic limbs exhibited depressed L-type Ca2+currents, GTPγS-induced transient receptor potential cation channel (TRPC)-like currents, 80 mM KCl-induced vasoconstriction, TRPC6 mRNA, and voltage-gated K+and inwardly rectifying K+currents. Exercise training abrogated the differences in all of these functions between atrophic side and contralateral side DFA myocytes. These results suggest that a probable increase in hemodynamic stimuli in skeletal artery smooth muscle plays an important role in maintaining MR and ionic currents in skeletal artery smooth muscle. This may also explain the observed benefits of exercise in patients with limb paralysis.

NEW & NOTEWORTHY Myogenic responses (MRs) in rat skeletal arteries feeding the unilateral atrophic hindlimb were impaired. In addition, the L-type Ca2+channel current, the TRPC6-like current, and TRPC6 mRNA levels in the corresponding myocytes decreased. Voltage-gated K+channel currents and inwardly rectifying K+channel currents were also attenuated in atrophic side myocytes. Exercise training effectively abrogated electrophysiological dysfunction of atrophic side myocytes and prevented loss of the MR.
The New Hilger Microfocus X-Ray Generator and Its Applications
Authors: Brech Frederick , Stansfield J. R.
Published: March 2019

In X-ray diffraction techniques intensity of radiation is an important factor. In addition, when high resolution is required, the usual collimating system restricts the width of focus that can be effectively used. Accordingly, a prime requirement is that the target loading shall be high to give the greatest possible brilliance at the focus. An X-ray unit designed to achieve these qualities will be described. Its use with a spectrometer and with a number of cameras for differing crystallographic studies will be illustrated.

The tube operates with alternative electron guns, one of them to provide a circular focus of 40 microns in diameter and the other to provide a line focus of 1.4 millimeters in length and 0. 1 millimeter in width.
Early Aging Effects in Copper - 1.76% Beryllium Single Crystals
Authors: Evans Doris
Published: March 2019

A technique is described for the study of the early stages of precipitation hardening in single-crystalline and poly crystalline copperberyllium alloys. Since no trace of the equilibrium precipitate responsible for hardening can be detected by ordinary X-ray or metallographic techniques prior to the onset of overaging, the described method is based on the changes produced in the matrix as the result of the formation of aggregates along preferred lattice planes. Such formations produce accommodation strains in the matrix lattice which, can be detected as a change in the intensity and angular range of matrix reflection.

An interpretation of the age hardening sequence in a copper - beryllium, alloy after isothermal annealing is presented in terms of fundamental transformations.
Application of the Microemission X-Ray Spectrograph. Comparison of Analyses from Small Areas
Authors: Norton J. F.
Published: March 2019

Techniques of determining spot size and sensitivity of the instrument will be developed. Spot sizes of the order of 5 microns have been obtained with the possibility remaining for improvement- Preliminary sensitivity measurements indicate that micro-microgram quantities of some elements are sufficient to be detected. Difficulties involved in finding desired target areas will be discussed. The inhomogeneities of standard samples used for conventional fluorescense X-ray quantitative analyses precludes their use for microemission techniques at least in some cases. Possible ways of determining homogeneity will be discussed. Analysis which can be performed to advantage may be classed into several categories.

1.

The changes in composition occurring in grain boundaries can be detected and compared with the base material.

2.

An inclusion, in a metallic material can be brought under the electron probe and analyzed independently of the base material.

3.

Changes in composition across a boundary between solid phases can be measured.

4.

Diffusion coefficients between solid phases may be determined.

5.

Thickness of thin films and variations in film thickness can be measured.

Examples of the instrument's performance will be given in some of these categories.
A Theoretical Derivation of the Composition of Mixable Specimens from Fluorescent X-Ray Intensities
Authors: Sherman Jacob
Published: March 2019

A rigorous solution is developed for the correlation of the composition of mixable specimens and the fluorescent X-radiation emitted by the elements in the specimen. The instrumental modifications and treatment of the specimens are derived from the fundamental fluorescence equation.

The resultant dilution formula contains measurable quantities only. No calibration curve is required.

The theory is illustrated by some experimental data confirming the equations.
A Novel Approach to Discrimination in X-Ray Spectrographic Analysis
Authors: Lublin Paul
Published: March 2019

There are various methods for handling the problem of interferences. One may me one of the weaker lines of the trace clement, but this results in considerable loss in the limit of detectability of this element. One may try pulse height discrimination techniques, but because of the linearity limitations of present day pulse height analyzers, complete elimination of the higher energy wave length is not possible. Another possible technique is to lower the kilovoltage below the excitation potential of the interfering element. This is satisfactory, but again the limit of detectability is raised for the trace element. There are many other “devices” which may be tried, but all of these involve a loss in sensitivity in the determination of the trace element.

The “novel” approach involves the use of an analyzing crystal whose second order reflection is missing due to crystal structure considerations. Germanium or silicon, cut so that (111) planes are parallel to the surface of the crystal, would be satisfactory analyzers for this purpose. The use of one of these crystals and the application of this method to the niobium-tantalum and zirconium-hafnium systems are discussed.
Crystal Chemical Studies by X-Ray Fluorescence
Authors: White Eugene W. , McKinstry Herbert A. , Bates Thomas F.
Published: March 2019

The wavelength of the characteristic X-radiation for the lighter elements is not constant but is a function of valence state and to a much lesser extent is a function of co-ordination number.

Commercially available X-ray fluorescence equipment is used in detecting shifts in the characteristic radiation for aluminum, sulfur, chlorine, titanium, vanadium and iron. The greatest shift is found in the case of chlorine where, using the NaCl analyzer, a shift of nearly 0.2° 2 θ is obtained in going from the Cl− in cholorides to the Cl+7 in the perchloratc. The wavelength of the Al+3Kα varies slightly as a function of co-ordination number.

Examples are given for using these phenomena in studying minerals and other compounds. The feasibility of extending the study to both heavier and lighter elements is explored.
An X-Ray Fluorescence Method of Analysis of Microsamples
Authors: Reisdorf B. G.
Published: March 2019

A method is described for the analysis of microscopic samples that utilizes a commercial electron diffraction unit for the excitation of fluorescent X-rays in a specimen and photographic recording of the resulting spectra by a small fluorescenceanalysis camera placed within the electron diffraction unit. Applications of this method to the analysis of precipitates extracted from steels are included in the discussion.
A High-Temperature Study of Phase Precipitation in Superalloys
Authors: Radavich John F.
Published: March 2019

Many of the iron- and nickel-base superalloys exhibit brittle properties on heat treatment, welding, or other fabrication processes at temperatures of about 2000°F or higher. Studies have been carried out by means of electron microscopy, electron diffraction, and X-ray diffraction and fluorescence analysis of the precipitation in the metal and in an isolated form.

Results of the electron microscope study of the surface of the metal show a grain boundary constituent to be present which increases in amount as the temperature is increased. Studies on the isolated residue of such samples show a very thin “featherlike” film to be located at the grain boundaries and enclosing the grains. Electron diffraction, X-ray diffraction, and X-ray fluorescence analysis studies of the thin films indicate that they are a TiC phase with very little alloying elements in solution.

At temperatures above 2000°F the thin film becomes quite thick and tends to force the grains apart. It is believed that this form of the TiC phase promotes the severe embrittling nature of these alloys at high temperatures. Suitable heat treatment at lower temperatures causes the TiC film to agglomerate and the grain boundaries become “tight,” and a more ductile condition results.
The Use of Computer Techniques to Plot Pole Figures
Authors: Holland J. H. , Engler N. , Powers W.
Published: March 2019

A method has been derived and is currently being used to plot normalized pole figures by computer techniques. As the pole distribution traces, i.e., intensity of the diffracted X-ray beam, versus angular position of the specimen are not an acceptable input for the computer, the data required from such traces are entered onto IBM punch cards. Corrections for defocusing effects may be readily made as the data are transferred from the Brown recorder traces to IBM punch cards. It is possible to program other correction factors into the computer operations providing that these correction factors or curves can be established accurately. The computer translates angular position of the specimen into reactiiinear coordinates which are an identical representation of stereographic coordinates. This computer method has been used in conjunction with the Schulz reflection technique, but modification of the computer program permits its use with other quantitative X-ray techniques for determining preferred orientation.

The feasibility of using computer techniques to plot inverse pole figures has been considered.
X-Ray Studies of Basic Lead Azides
Authors: Stammler M. , Abel J. E.
Published: March 2019

Basic lead azides are obtained by the slow thermal decomposition of PbN6 at temperatures up to 200°C in oxygen, argon, and air containing varying amounts of moisture. The decomposition diagrams show several stages due to the formation of different phases, two of which have been separated. One phase can be identified as a tetragonal deformed cubic lattice. Further slow decompositions of the basic lead azide at 250°C lead to tetragonal lead oxide. The structure of the other isolated phase Is of lower symmetry and has not yet been classified. The results of this investigation are also compared with the work of previous investigators.
A Simple Goniostat for the Norelco Diffractometer
Authors: Hubbard William M. , Gilfrich John V.
Published: March 2019

A simple single-crystal goniostat has been built for the Norelco X-ray diffractometer using a modified eucentric goniometer head and the basic geometry of the Norelco pole-figure device.

The goniometer head was modified to provide interchangeable mounting tn the goniostat, a two-circle optical goniometer, or the sample holder of a flat-plate camera.

With this device one can orient and mount a. crystal along any desired direction in a fraction of the time required by conventional film techniques, thus reducing the mounting of a sample for intensity measure ment s for structure determinations or for measurements of anisotropic physical properties to a routine procedure.
The Effect of Particles and Surface Irregularities on the X-Ray Fluorescent
Intensity of Selected Substances
Authors: Gunn E.L.
Published: March 2019

Selected substances have been examined by X-ray fluorescence to determine the effect of particles or surface irregularities on the fluorescent intensity. The powdered substances examined were segregated into particle size classifications by the use of standard and micro sieves and ocular microscopic measurements. The substances thus classified were Iron, germanium, and titanium metals, copper furnace slag, and a cobalt molybdate catalyst. Graphical representations are used to characterize the relation between particle size and intensity. In certain cases the influence of particle size is expressed in terms of a calculated absorption length of the substance. The extent to which particle size in a powder affects the fluorescent intensity is a function of the absorption coefficients of the substance for the exciting and fluorescent X-rays, The effect on intensity of successive powder dilution of a high atomic number witha low atomic number substance has been measured. The results are of assistance in providing a concept of the structure necessary for maximum intensity. Little difference in the fluorescent intensity of an element is exhibited as between its dilution in a dry powder and in an aqueous solution, if the absorption properties of the two diluents are very similar. The effect of small surface irregularities in a metal exhibits no systematic relation to the fluorescent intensity.
Norelco Pinhole Attachment
Authors: Miller D.C.
Published: March 2019

An adapter for a standard Norelco spectrographte attachment will be described which permits the examination of a selected area of the specimen by X-ray fluorescence analysis. The size of the area can be varied depending upon the choice of pinholes with sizes available dovwi to 0.010 in. or 250μ. The sample is placed into a specially modified sample holder so that it can be moved at orthogonal directions under the beam from outside the spectrograph while the sample is under X-ray irradiation. Dam on applications will also be given.
X-Ray Diffraction Studies at Low Temperatures
Authors: Barrett Charles S.
Published: March 2019

Much current solid-state research, particularly that concerning the Fermi surfaces of metals and semimetals, demands knowledge of lattice parameters at temperatures in the liquid-helium range. A helium cryostat diffraction apparatus that has been in continuous use at these temperatures will be described, and some new research results from it are presented. The results include measurements of the lattice constants for gallium and for indium, of interest because the axial ratio influences both the nuclear electric quadrupole spectrum and also the cyclotron resonance. Previous measurements have disclosed unusual expansion characteristics but have not extended below liquid-nitrogen temperature.

A second area in which the cryostat has been operating is the determination of the temperature of beginning recrystallization in high-purity metals that recrystallize at low temperatures. Experiments with zone-refined lead which has a recrystallization temperature near 160°K are reported.
X-Ray Diffraction Investigation of the Sn-Hg Phase in Dental Amalgam*
Authors: Fairhurst Carl W. , Ryge Gunnar
Published: March 2019

Dental amalgam has been used as a filling material in dentistry for over 100 years. The reactants, Ag3Sn alloy and mercury, form silver-mercury and tin-mercury products. Previous X-ray diffraction studies have resulted in some disagreement concerning unit-cell structure and parameters of the products. In this study, X-ray diffraction measurements were carried out on tin-mercury mixtures, tin-mercury alloys, dental amalgam, and single crystals of tin and mercury. The diffraction data for the tin-mercury alloys were programed for an IBM 650 computer utilizing Cohen's least-squares method. The tin-mercury product was found to be a solid solution possessing hexagonal-symmetry elements. The parameters ranged from: c0= 2.995 A to 2.984 A, co/ao= 0.931.
Determination of Accurate Lattice Parameters Using a Diffractometer
Authors: Geiss R.H.
Published: March 2019

Without modifying the General Electric XRD-5 diffractometer accurate lattice parameters of cubic structures may be determined quite simply and precisely. The method is applicable to both solid and powder samples and gives a precision of at least ±0.00025 A. The most important step in the analysis is the alignment of the diffractometer. The specimen must be in the exact center for precise work. However, after the initial alignment, daily alignment is a routine matter. This technique for lattice-parameter determination will also be useful for determining thermal coefficients of expansion and residual-stress measurements.
A Study of Cuban Todorokite
Authors: Faulring G. M.
Published: March 2019

Todorokite is a hydrated manganese oxide mineral containing small amounts of sodium, potassium, calcium, barium, magnesium, iron, and aluminum. From the reports of other investigators and observations in our laboratories, todorokite appears to be a more widely occurring mineral than generally recognized.

It was found by X-ray diffraction that a sample of todorokite from Charco Redondo, Cuba, had a high degree of preferred orientation and that milling for a prolonged period of time was necessary to obtain random orientation in a mounted specimen. The position of the preferred orientation direction with respect to the X-ray beam is the principal factor determining the relative intensities on an X-ray diffraction pattern. Based on fiber data, the unit cell of todorokite is considered to be pseudo-orthorhombic or triclinic with α, β, and γ angles varying slightly from 90° and cell dimensions of a0 = 9.65A, b0 = 10.29A, and c0 = 2.84A, This deviation from orthogonality may account for the diffuse and distinct reflections typical of X-ray diffraction patterns of todorokite. Optical data and a hypothesized paragenesis of Cuban todorokite are also included.
High-Temperature Furnaces for X-Ray Diffractometers
Authors: Campbell William J. , Stecura Stephan , Grain Clark
Published: March 2019

This paper summarizes developments in the field of high-temperature X-ray diffractometers through 1959, evaluates various furnace designs, and describes briefly the X-ray diffraction facilities of the Federal Bureau of Mines.

X-ray optics, for those furnaces that have precision sample movements, are equivalent in resolution and line profile to conventional X-ray techniques. There is a 10-25% loss of intensity due to absorption of X-rays in the furnace windows, magnitude of which depends on wavelength and type of window used, and a reduction (5–40° 2θ) of useful angular range from limiting X-ray windows, radiation shielding, or the viewport for an optical pyrometer. In oxidizing atmospheres, temperatures up to 1500°C were obtained with furnaces wound with platinum—20% rhodium wire. Under nonoxidizing conditions temperatures of 1800 to 2000°C were obtained with both tantalum-foil and tungsten-wire heaters.

Accurate temperature measurement over the area and depth of samples being studied is the most difficult problem in high-temperature X-ray diffractometry. Below 500°C, there are several furnace designs which are reported to reduce thermal differentials to less than 1°C across the sample. However, at temperatures around 1000°C, there are thermal gradients of 20-30°C/cm across the sample and 100–600°C/cm through the sample holder, making thermocouple location critical. Secondary standards have been used extensively to calibrate the furnaces; however, there is disagreement concerning which are the most reliable data to use. For these reasons, plus others discussed in this report, there is a probable error in the temperature determination of ±10 to 20°C at 1000°C, with the error increasing with temperature.
Alignment Device and Thermal-Control System for High-Temperature X-Ray Diffractometry
Authors: Corvin I. , Schossberger F. , Ticulka F.
Published: March 2019

A high-temperature high-vacuum X-ray diffractometer attachment was constructed to observe formation of materials at elevated temperatures. The device consists of a conventional water-cooled compartment, a resistance-type furnace for heating samples to 800°C, and inlets and outlets for gaseous reactants and evacuation. Two sources are available for evaporation of materials which may react with or coat the sample. The sample is aligned by a two-part sample-slit system. The sample temperature is regulated by means of a current-adjusting control unit and a self-saturating reactor with suitably positioned thermocouples. Temperature distribution and constancy over the sample surface were determined.
Heterogeneity Effects in X-Ray Analysis*
Authors: Claisse Fernand , Samson Claude
Published: March 2019

A fundamental quantitative treatment of the heterogeneity effects in X-ray fluorescence has been made. The theory predicts that the grain-size effect appears only in a limited region of grain sizes which depends on the wavelength of the primary radiation and the nature of the compounds in the mixture. With monochromatic radiation, the fluorescence intensity showed increase or decrease by a factor of a few units as grain size is decreased, A factor as large as 12, the theoretical value, has been observed in one particular experiment. Usually the grain-size effect can be eliminated by intensive grinding. For the light elements fine grinding is disastrous if long wavelengths are used. By an appropriate choice of the wavelength it is possible to eliminate the effect even without grinding. The mathematical treatment also predicts, but less rigorously, a grain-size effect in X-ray diffraction.

The effect on the fluorescence intensities by changes in the chemical composition of the grains that contain the fluorescent element is predicted by the theory.

These findings are discussed in relation to the analysis of elements when polychromatic beams are used.
Some Special Sample-Mounting Devices for the X-Ray Fluorescence Spectrometer*
Authors: Bertin Eugene P. , Longobucco Rita J.
Published: March 2019

Various sample-mounting devices are described for use with a commercial flat-crystal X-ray fluorescence spectrometer having conventional (i.e., not inverted) geometry: (1) a sample drawer with two sample “spinners,” one for rotation of flat samples in their own plane, the other for rotation of cylindrical or filamentary samples about an axis normal to the plane defined by the directions of the primary and secondary X-ray beams; (2) rotatable mounting stages for filter paper disks and various very small samples; (3) a sample drawer for selected area operation with pinhole or slit apertures in the primary beam or pinhole apertures in the secondary beam; (4) a liquid cell with 0.00025-in. Mylar window (the cell is inexpensive, easily filled and rinsed, and usable 20-50 times before the window must be replaced); (5) three types of cell for powder samples (one has a 0.00025-in, Mylar window and is filled through a port in the top; the other types are open on both sides and are filled by placing them on glass plates and introducing the powder from the back; one of these back-loading cells permits rotation of the powder sample); (6) rotatable stages for briquetted powder samples; (7) mounting devices for wire samples on small spools (one of these devices permits rotation of the spool).

These devices were designed and made at the X-ray laboratory of the RCA plant at Harrison, N. J., and have been used there successfully with a wide variety of samples for several years.
Vacuum X-Ray Instrumentation and its Application to Mill-Products Control
Authors: Dryer H. T. , Davidson E. , Andermann G.
Published: March 2019

With the introduction in 1960 of the first commercial multichannel vacuum X-ray spectrometers, ARL opened the way for greater economy of operation for light-element analysis over conventional helium-path instrumentation. The design concepts and features of these instruments are discussed, including the adaptability to “on-stream” or continuous analyzer programs. The successful application of vacuum X-ray equipment for the analysis of ores, concentrates, and slags will be presented. Factors relating to sample preparation, precision, and accuracy are given and analytical sensitivity and speed are covered.
X-Ray Probe with Collimation of the Secondary Beam
Authors: Heinrich Kurt F. J.
Published: March 2019

An attachment to a commercial flat-crystal X-ray fluorescent goniometer permits analysis of small areas. The selection of the sample area is achieved by collimating the secondary beam. The geometry of the probe, its stage, and counting statistics applied to the probe are discussed. Experimental data are shown referring to determination of spot size, counting rates obtained, and both qualitative and quantitative applications.
X-Ray Measurement of the Static Lattice Distortion in the Solid Solution of Oxygen in Titanium*
Authors: Schoening F. R. L. , Witt F.
Published: March 2019

Oxygen was introduced into a single crystal of titanium in successive stages. The intensities of the h00 and 00l reflections were measured with a single-crystal diffractometer. The observed variation of the intensities with oxygen concentration was attributed to three factors: (1) the additional scattering from the oxygen atoms, (2) a change in the Debye-Waller factor, and (3) an exponential factor originating from the distortion around the oxygen atom. The theory of X-ray scattering from crystals containing centers of distortion was applied to the hexagonal titanium containing interstitial oxygen atoms. Using the variation of the lattice constant with oxygen concentration, it was possible to predict the intensity reduction due to lattice strains. It was concluded that it would have been possible to obtain an estimate of the defect concentration from the X-ray measurements of lattice expansion and intensity reduction.
Measurement of the Lattice Constants of Neon Isotopes in the Temperature Range 4–24°K
Authors: Bolz L. H. , Mauer F. A.
Published: March 2019

Using an X-ray diffractonieter cryostat, the lattice constants of the isotopes20Ne and22Ne as well as the naturally occurring mixture have been measured throughout most of the temperature range in which they exist as solids (0 to approximately 24°K), The heavier isotope has the smaller lattice constant, the values obtained at 4.2°K being:20Ne—4.4624Å,22Ne—4.4540Å, and11Ne—4.4622Å. The absolute error in these values is believed to be no greater than 0.001 A. The volume expansion coefficient, which does not appear to differ significantly in the three cases, increases to a value of 6.3 × 10−3/°K at 24°K.
Recent Advances in Electron-Probe Analysis
Authors: Long J. V. P.
Published: March 2019

The electron-pro be analyzer has been developed in a period of thirteen years to a point where several different instruments are commercially available and about one hundred are already in use. At the present time it is possible to analyze volumes of about 1 μ3 at the surface of a specimen for elements above sodium in the periodic table with a concentration sensitivity of the order of 0.1-0.01%. New developments in the field include efforts to extend the range of Z to lower atomic numbers and to increase the spatial resolution of the method so that smaller volumes niay be analyzed. Progress in the analysis of the light elements centers at present mainly on the use of nondispersive detectors and. computer techniques for the resolution of overlapping pulse-height distributions. With such methods qualitative detection of elements down to beryllium has been achieved in the presence of their near neighbors. Efforts to increase the spatial resolution of the probe have led to the use of thin specimens which are partially transparent to electrons. Partly as a consequence of this approach, apparatus has been developed in which an electron microscope with facilities for selected area diffraction has been combined with an electron-probe analyser. The ever-widening range of application of the electron-pro be technique has inevitably disclosed problems in the interpretation of quantitative data, and it is clear that at the present time more information on the process of X-ray production by electrons is required before semi-empirical methods can be entirely eliminated. Examples of the use of the method in metallurgical and mineralogical studies illustrate some of the current trends in the refinement of measurement technique and interpretation of experimental data.
The Use of X-Ray Emission Spectrography for Petroleum Product Quality and Process
Control
Authors: Caley J. L.
Published: March 2019

A Norelco Autrometer (automatic multielement X-ray spectrograph) is being used by a petroleum refinery control laboratory for process control and product quality control. As many as 100 analyses covering 13 elements are run per day. Concentrations range from a few ppm to 25%.

The instrument has reduced the elapsed time for many analyses from 8 hr to 5 min, made possible in many cases greater accuracy than previously used wetchemical methods, reduced laboratory manpower and increased refinery production efficiency in many instances.
The Debye Temperature of Iron-Manganese Solid Solution Alloys
Authors: Gazzara Charles P. , Middleton Raymond M.
Published: March 2019

Values of the Debye temperature 0 for iron-manganese solid-solution alloys have been determined from X-ray diffracted intensity measurements of powder specimens at ambient temperatures of 310, 239, and 98°K. Corrections to 0 were made with respect to the temperature-dependence of Θ, temperature diffuse scattering, dispersion, volume expansion of the alloy, and the temperature gradient through the specimen. The variation of Θ with temperature has been found to be approximately linear, the value of Θ decreasing 3 % between 98 and SICTK. for a nominal Fe–4%Mn alloy.

Increasing the concentration of manganese in an iron-manganese solid-solution alloy decreases Θ in qualitative agreement with Lindemann's equation. The values of Θ for other s olid-solution alloys computed using Lindemann's equation also agree with reported experimental values of Θ. The Debye temperature of a nominal Fe-3%Mn alloy annealed for 2 hr at 300, 600, and 700°C has not been found to maximize at 600°C as has been reported by Il'ina et al. On the contrary, Θ decreases with increasing annealing temperature until, in the range 600 to 700°C, it reaches its true value; and at these temperatures the powder was found to be fully annealed.
Relation Between Ionic Radii and Transformation Temperature in Rare Earth Niobates
Authors: Gingerich K. A. , Bair H. E.
Published: March 2019

In this work a detailed X-ray powder diffraction study of the reversible temperature transformation has been undertaken in several rare earth niobates MNbO4 M being lanthanum, cerium, neodymium, gadolinium, holmium, thulium, ytterbium, and yttrium. Both high-temperature diffractometer and film techniques were used. It was shown for the substances investigated that the low-high transformation is a continuous transition over the wbole temperature range from monoclinic at room temperature to tetragonal at the transition temperature. It was found that the rate of the overall transition is rapid, and also that the transition between any intermediate state occurs reversibly within minutes or seconds. The continuous transition and the rapid rate of attainment of equilibrium in the solid, even between intermediate states of the transformation, support the earlier assumption that it is a displacive-type order-disorder transition.
Quantitative Determinations and Descriptions of Preferred Orientation*
Authors: Holland J. R.
Published: March 2019

The problems associated with quantitative determinations and descriptions of preferred orientation are discussed and a method proposed to yield quantitative descriptions. A means of obtaining representative quantitative data using reflection techniques is described. The position of intensity minima in quantitative pole figure descriptions of preferred orientation is equal in importance to intensity maxima. Hence, rate-meter counting of diffracted intensity as the sample is continuously or semicontinuously rotated in a given spatial relationship is not satisfactory. Instead, sealer counting by fixed counts at a given spatial position yields more meaningful results; however, fixed-time sealer counting is used to reduce the time for data collection. The data are plotted in the form of normalized pole figures and analyzed.

To determine the relative volume of material associated with a given-texture component and an index of preferred orientation, the data are integrated. This is done by numerical integration or, alternatively, by graphical means. Integrating over the interval from ϕ = 0 to ϕ = π/2 and α = 0 to α = n/2 (where ϕ and α are spherical coordinates) will give the pole concentration per unit area for an ideally randomly oriented specimen for an octant of the sphere of projection. The relative volume of material associated with a given set of intensity maxima can be determined by integrating the intensity over the area of the maxima, summing these values, and dividing by the multiplicity to obtain the total intensity, It. The relative volume can be expressed as a ratio of It divided by random intensity. The texture strength can be expressed as the standard deviation from the random condition. Such information is vital to quantitative predictions of the anisotropy of properties
Vacancy Related Defects in Antimony-Doped Silicon
Authors: Howard J. K. , Miller D. P.
Published: March 2019

Helical dislocations and vacancy aggregates have been reported in lithiumdoped germanium and in diffused silicon. In the present study, defects related to an excess vacancy concentration are examined in as-grown silicon. X-ray topography, etch techniques, and Hall effect are used in determining the conditions of formation of these imperfections. Two distinct types of defects are observed: (1) helical dislocations and (2) dislocation loops. The helical dislocations are identified in the X-ray topographs and correlated to their etch figures. The diameters of the helices in various crystals range from less than 10 to 100 μ. The largest concentration of helices are observed in the initial growth, but prismatic loops or helical segments are also present in the low dislocation density regions of some crystals. The dislocation loop image consists of a pair of opposed arcs. The lengths of images vary from 30 to 400 μ, and the axis of the loop is usually parallel to <110> linage contrast changes with changes in sample orientation, but conclusive Burgers vector determinations are incomplete.

The formation of these defects is shown to be directly related to the heat treatment during crystal growth. The total acquisition of vacancies during growth is quite high and is attributed to the “orbital” growth process. In the “orbital” method, the seed check rotates 8-9 rpm about the center of the crucible as the growing crystal rotates 50-60 rpm. A linear relationship exists at room temperature between the vacancy concentration and the antimony impurity concentration. Impurity concentrations were determined independently by chemical and mass spectrograph techniques. A defect complex involving V− and Sb+ in thermal equilibrium is employed to explain this effect.
Preferred Orientation in Ceramic Materials Due to Forming Techniques
Authors: Pentecost Joseph L. , Wright Charles H.
Published: March 2019

Accurate measurement of the electrical and mechanical properties of polycrystalline oxide ceramics has revealed anisotropy in a number of properties. The source of this anisotropy may be attributed to a number of causes, however, with oxides having anisotropic crystals, preferred orientation of the crystallites may be suspected. Aluminum oxide and beryllium oxide ceramics samples of high purity and density were formed by slip casting, dry pressing, isostatic pressing, and extrusion. Pole figures for the (113), (110) and (030) planes in aluminum oxide and (100) and (103) planes in beryllium oxide were prepared by using a Siemens automatic pale figure goniometer.

It was found that both slip-cast oxide samples and dry-pressed aluminum oxide samples and dry-pressed beryllium oxide samples showed sufficient preferred orientation to prepare a pole figure from the data. The actual preferential orientation of the crystallites in these two oxides is discussed and the pole figure information presented. The effect of furnace atmosphere and surface contaminants on re crystallization at an exposed surface is covered briefly.
X-Ray Investigation of Aerosols from Wires Exploded in Nitrogen
Authors: Karioris Frank G. , Woyci Jerome J.
Published: March 2019

Wires of 18 different metals were exploded in nitrogen by the discharge of a 20-μF capacitor bank charged to 10 kV. The resulting aerosols were collected under nitrogren on membrane e filters, which were mounted on glass slides and used directly in the sample holder of a recording X-ray diffractometer. The X-ray data were analyzed to determine the composition and approximate crystallite size of the particulates produced by the wire explosions in nitrogen and subsequent exposure to air.

Nitrides are found as reaction products from the explosion in nitrogen of aluminum, iron, indium, tantalum, thorium, uranium, tungsten, and zirconium. No nitrides were detected in the samples from cadmium, copper, magnesium, molybdenum, lead, and tin explosions, although such nitrides are known to exist; and the aerosols produced in nitrogen by the explosion of silver, gold, molybdenum, platinum, and tin consist almost entirely of metal particles. Oxides are attributed to contamination of the nitrogen or exposure of the samples to air.

Most of the crystallites observed are less than 1000 Å as determined from X-ray line broadening find confirmed in some instances by electron microscopy. For the UN2 and ThO2, crystallite sizes of the order of 130 Å and 50 Å, respectively, are observed. In samples comprised of a mixture of phases, the constituents usually have different mean crystallite sizes. The crystallite size is not affected dramatically by the ambient nitrogen pressure or voltage used.
Technique of Measuring Low Percentages of Retained Austenite using Filtered X-Ray Radiation and an X-Ray Diffractometer*
Authors: Erard H. Robert
Published: March 2019

This paper describes a technique of measuring the volume percent retained austenite in steel using ordinary filtered X-radiation and an X-ray diffractometer. As compared with conventional rate-meter recordings or microphotometer traces of diffraction peaks, the subject technique extends the range of austenite determinations from the usual 7 % down to 1 %. It markedly improves over the entire range of measurement.

Essentially, the technique consists of step scanning the profile of each selected martensite and austenite diffraction line and recording the corresponding intensity within a known probable error. The step-scanning, fixed-count, and counting-rate, recording operations are performed automatically by a counting-rate computer. The integrated intensity of each diffraction line is obtained by summation of intensity increments above background in accordance with the “trapezoidal rule.” For hardened steel, the best peak-to-background ratio is secured using filtered Cr Ka radiation with the vanadium filter located in the diffracted beam. The volume percent retained austenite is determined by direct comparison of the integrated intensity of an austenite line with the integrated intensity of a marten site line and from the relationships between intensity and concentration for the martensitic and austenitic phases.

An application of the subject technique was its use in determining the retained austenite behavior of carburized 9310 steel. The volume percent austenite retained on the surfaces of as-quenched specimens was determined as a function of carburizing potential. The amount of retained austenite subsequently transformed by various combinations of tempering, refrigerating, and retempering treatments was successively ascertained. The amount of retained austenite determined using the subject technique compared closely with the amount of retained austenite measured by metallographic examination. However, the reproducibility of results was better for the X-ray method as compared to metallographie examination. The nondestructive nature of the X-ray method permitted successive measurements on the same surface following repeated thermal treatments.
Methods of Quantitative Electron Probe Analysis*
Authors: Wittry David B.
Published: March 2019

Methods of quantitative electron probe analysis using empirical working curves have achieved only partial success because of variations in instrument design, analysis conditions, and homogeneity of standards. These problems have been solved for X-ray fluorescence analysis, but many of the more successful empirical methods cannot be used in electron probe analysis; instead, a more theoretical approach is indicated. In electron probe analysis quantitative results can be achieved with only pure elements as standards provided (1) the analysis conditions are carefully selected, (2) the observed intensities can be corrected to obtain the primary intensity actually produced in the specimen, and (3) the relationship of the primary intensity and concentration can be calculated. While present methods of making some of the corrections required improvement and a “universal” theory for relating the primary X-ray intensities to the concentrations still does not exist, the success achieved with this approach indicates that it should be used to the fullest extent before resorting to calibration curves. Moreover, as information is accumulated, the number of cases requiring the use of calibration curves should diminish, so that eventually it may be possible to perform quantitative analysis in any system with only pure elements as standards,
X-Ray Fluorescence Analysis for Sodium, Fluorine, Oxygen, Nitrogen, Carbon, and Boron*
Authors: Henke Burton L.
Published: March 2019

Optimized vacuum spectrographic measurement of low-energy fluorescence has been found to yield counting rates and peak-to-background ratios which are enough to permit the extension of fluorescence analysis for elementary chemistry into the light-element range—sodium through boron. This is accomplished with an efficient, demountable ultrasoft X-ray source, with close coupling among source, crystal, and detector, with KAP and multilayered stearate analyzers, and with, optimized flow-propordonal counting. Specific methods for achieving peak-to-background ratios on practical samples containing these light elements are presented. The extension of these methods of light-element analysis with the use of curved long-spaced crystals for X-Ray macroprobe and electron microprobe measurements is discussed. The design and construction of multilayered soap film “crystals” for long-wavelength X-ray analysis is described.
Experimental Dispersing Devices and Detection Systems for Soft X-Rays
Authors: Fischer David W. , Baun William L.
Published: March 2019

Instrumentation for soft X-ray research is briefly described. Preliminary results are shown for several dispersing systems which have been found useful in the 10 to 60 Å region. Results from single crystals of Group 1A salts of phthalic acid are discussed and intensity measurements are reported. Other organic single crystals, such as long-chain derivatives of adipic acid are evaluated, along with films of organic compounds prepared by the Blodgètt-Langmuir technique. The efficiencies of the dispersing elements mentioned above are compared with commercial crystals such as mica, gypsum, ADP, and EDDT. Performance of detectors for soft X-rays is shown for fiow-proportional and Geiger counters, a solid state silicon barrier detector, and a windowless resistance strip magnetic electron multiplier. The relative efficiencies of several photocathode materials for the latter are discussed. The design for a scintillation counter sensitive over a wide energy range is discussed and preliminary results using the counter in the region 1-15 Å are shown.
The Accurate Determination of Major Constituents by X-Ray Fluorescent Analysis in the Presence of Large Interelement Effects
Authors: Lucas-Tooth J. , Pyne C.
Published: March 2019

Fluorescent X-ray spectrometers bave a high inherent reproducibility. It is possible to achieve results, on a routine basis, which have a coefficient of variation of less than 0.1%. Given extremely good chemical standards and the absence of interelemental effects, these readings can be interpreted into percentage concentrations with the same order of accuracy. Results, with this accuracy of analyses of copper in a straight brass will be given. With samples of greater complexity and more elements the interelement effects are large and have to be tackled. A correction method has been established and will be explained in detail.

As an example of the method it was decided to tackle the determination of
chromium at high concentrations (7-32 %) in high-alloy steels containing additions in the following ranges: Si, 0.2-2.4%; Al, 0,07-5%; Cu, 1,3-3.6%; W, 0.25-3%; V, 0.1-0.3%; Nb, 0.1-0.3%; Mo, 0.1-4.4%; Ti, 0.05-1%; Mn, 0.35-10%; Ni, 0.2-24%. These very wide alloy specifications were a severe test on the accuracy of the chromium determination & the correction for interelement effects.
Mineralogical Problems in X-Ray Emission Analysis of Sylvite Concentrates
Authors: Bernstein Frank
Published: March 2019

Mineralogical effects, which relate to the occurrence of an element in different forms of chemical combination, often are a problem to the X-ray analyst since these forms usually differ in X-ray sensitivity. An example of this is cited in connection with the analysis of sylvite concentrates for potassium. An evaluation is made of mineralogical effects and a quantitative relationship between X-ray intensity and mineral form and particle size is derived. If the particle size of a minor constituent is reduced sufficiently the mineralogical effect disappears. Target materials for X-ray sources are found to have only minor effects on relative intensities of different compounds of an element. Finally, it is concluded that the advantages of higher intensities gained through the use of target materials close in atomic number to the material being analyzed far outweigh particle size effects which are shown to be relatively small.
Performance of an Unattended Automated X-Ray Spectrograph
Authors: Davis C. M. , Yanak M. M.
Published: March 2019

Among the advantages of the X-ray spectrograph is the economy realised by minimizing the time of analysis. In the past few years automated features have been developed and applied to reduce analysis time further and to minimize operator errors. These have included a programmed goniometer, an automatic crystal changer, a digitized printer or automatic typewriter, and recently an automatic sample loader coupled with a programmer. With this last attachment, unattended analysis of solid metal samples has been achieved. The precision of data obtained automatically compares favorably with similar data obtained manually.