bluuebunny/crossref_metadata_2025 huggingface dataset:
Central nervous system signatures of affect in asthma: associations with emotion-induced bronchoconstriction, airway inflammation, and asthma control
Authors: Ritz Thomas , Kroll Juliet L. , Patel Sheenal V. , Chen Justin R. , Yezhuvath Uma S. , Aslan Sina , Khan David A. , Pinkham Amy E. , Rosenfield David , Brown E. Sherwood
Published: March 2019

The effects of asthma on affect have been noted for some time, but little is known about associated brain processes. We therefore examined whether emotion-induced bronchoconstriction, airway inflammation, and asthma control are related to specific patterns of brain activity during processing negative affective stimuli. Fifteen adults with asthma viewed alternating blocks of distressing film clips (negative condition), affectively neutral film clips (neutral condition), and a crosshair image (baseline condition) while undergoing blood oxygenation level-dependent (BOLD) functional MRI (fMRI). Block-design fMRI analysis evaluated the BOLD response to “negative-baseline” and “neutral-baseline” contrasts. Airway response to these film clips was also assessed with impulse oscillometry in a separate session. Measures of airway inflammation [fractional exhaled nitric oxide (FENO)] and asthma control [Asthma Control Questionnaire (ACQ)] were additionally obtained. A whole brain voxel-based regression analysis of contrast maps was performed against respiratory resistance increase during negative and neutral films, FENO, and ACQ. Peak airway obstruction to negative affective stimulation was associated with stronger activation of the anterior and middle cingulate gyrus, including the dorsal anterior cingulate cortex (dACC). Stronger airway inflammation and lower asthma control were associated with reduced activation to negative stimuli in the superior frontal gyrus, middle cingulate gyrus, and supplementary motor area. Activation of the dACC in negative-affect-induced airway obstruction could be part of an integrated defensive response to critical environmental change. In addition, reduced frontal and limbic activation during processing of negative affect may reflect consequences of pathophysiological processes for CNS functioning.

NEW & NOTEWORTHY This functional magnetic resonance imaging study shows, for the first time, that the degree of airway constriction due to negative affective stimuli in asthma is associated with stronger response to these stimuli in the dorsal anterior and middle cingulate cortex. Asthma patients with stronger airway inflammation and reduced asthma control also show reduced activation in a number of cortical and subcortical areas relevant for affective processing and breathing control.
A New Microemission X-Ray Spectrograph. Design and Operation of the Direct Emission Curved Crystal Instrument
Authors: Buschmann Erwin C.
Published: March 2019

The Microemission X-ray Spectrograph is the result of the consolidation of the fine focus electron optics employed in the X-ray microscope, and the spectrograph goniometer used in fluorescent X-ray analysis.

The electron beam, 5 microns in diameter, directly bombards the sample under study. The beam is focused using a three element electrostatic lens system.

Provisions are made for continuous sample viewing with light optics. Sample manipulation, provides for complete coverage of a sample one-half inch in diameter.

The characteristic X-rays generated at the sample are allowed to pass through a beryllium window and fall on the analyzing crystal.

The curved crystal diffracts the characteristic X-ray wavelengths and refocuses them at the bilateral slit ahead of the detector. The goniometer may either be hand operated or motor driven through the various 2 θ angles. Electron beam currents are regulated by controlling filament power oscillator output. Signals are fed through a preamplifier into a rate me ter and recorder or into a high speed sealer which may be set to count for accurate preset periods of time. Samples may be investigated either by complete spectrum analysis of a single point on the sample or by determining concentration changes of a particular element by moving the sample across the electron beam.
Annealing Texture in a Rolled and Artificially Nucleated Aluminum Single Crystal
Authors: Kohara S. , Parthasarathi M. N. , Beck Paul A.
Published: March 2019

It has been suggested that the experimentally observed orientation dependence of the mobility of grain boundaries in f.c.c. metals may be related to the dependence of the rate of self diffusion in grain boundaries on the disorientation across the boundary. Later, this relative orientation effect on the rate of boundary diffusion and self diffusion was experimentally observed. It was shown by Hoffman and Turnbull that in bicrystals of silver misoricnted around (100) by 9° to 28°, self diffusion along the boundary (parallel to the common (100)) may be described in terms of a coefficient of self diffusion in individual grain boundary edge dislocation pipes, orders of magnitude larger than the coefficient of lattice self diffusion. It is significant that the coefficient of self diffusion in grain boundary dislocation pipes was found to be independent of the misorientation (i.e., of the density of edge dislocations in the boundary) at least up to 28°, suggesting that even a boundary of such a great misorientation may be considered as a network of dislocations, as far as self diffusion is concerned.

In recent experiments the relative mobilities of boundaries in various orientations between a deformed (99.98% pure) aluminum single crystal and recrystallized grains growing in it in fairly well defined, lattice orientation relationships were compared. The matrix crystal was rolled to 80% R.A. on a (110) plane in a [112] direction, after which the strip still retained its initial orientation and the texture was very sharp. Recrystallized grains quite accurately oriented so as to have highest overall boundary mobility, i.e., corresponding to 40° rotations around the two 111 axes of the matrix grain lying in the rolling plane, were produced in large numbers by random nucleation on one side of the strip (rubbing one side with sandpaper and annealing). The re crystallized grains, that were at first growing in very large numbers and quite randomly but only in the thin surface layer highly deformed by abrasion (nucleation side), on annealing for 600 sec at 350°C grew across the whole thickness (0,010″) of the rolled single crystal. As a result of very selective growth, the recrystallized grains reaching the other side of the strip (growth side) showed a very sharp texture consisting of four components with the orientations described.
Further Application of the Intermediate X-Ray Probe
Authors: Adler Isidore , Axelrod Joseph , Branco Jaime J. R.
Published: March 2019

The electron probe is an extremely valuable tool for chemical analysis on a microscopic scale. There are many situations, however, that require analyses in the millimeter rather than micron range, where in fact, the use of the electron probe causes concern about sample homogeneity. The X-ray probe consisting of a small X-ray beam and focusing monochromator is very useful for this intermediate region. This X-ray probe is equally useful for electrically non-conducting as well as conducting specimens. Analysis need not be performed in vacuum and can be done with great rapidity.

For example by traversing a polished section of a combination of opaque minerals, it was possible to determine the distribution of copper, silver, arsenic, iron, and mercury and to show that an unidentified mineral was a copper arsenic mineral rather than an arsenoargentite as had been supposed.
The Evaluation of the PXQ for the Analysis of Cements and Related Materials
Authors: Andermann George , Jones J. L. , Davidson E.
Published: March 2019

The analysis of cements and ores has been studied using the Applied Research Laboratories, Inc. Production Control X-ray Quantometer (PXQ), Elements included in the program were magnesium, aluminum, silicon, phosphorus, calcium and iron. The PXQ, utilizing the polychromator concept, allows the simultaneous determination of the listed elements.

Focusing ADP, EDT, quartz and LiF crystals were used with flow Geigers or Multitrons. Helium paths were used as required. The choice of crystals, detectors, and slit widths was determined to give optimum results for each element.

The effects of briquetting and ratioing to scattered background on accuracy were studied. Various instrumental factors such as helium flow rate, detector gas flow rate, short and long term stability were also investigated.
Quantitative Analysis of Trace Amounts of Tin in Steel by Means of X-Ray Fluorescence
Authors: Whitehouse T. S.
Published: March 2019

X-ray fluorescence as a method of chemical analysis has been receiving considerable attention due to its inherent advantages of being non-destructive and generally less time consuming than conventional methods. A method of analysis is described using a pulse height analyzer in conjunction with the X-ray fluorescent unit which further extends the range of analysis.

This combination was used to measure tin in steel as low as .01% to an accuracy of .003%. Other similar analyses are suggested.
Metallurgical Applications of Electron Probe Microanalysis
Authors: Wittry David B.
Published: March 2019

The electron probe microanalyzer has found numerous applications in physical metallurgy. Some recent problems which have been studied with the microanalyzer constructed by the author at the California Institute of Technology include (1) determination of the penetration of chromium in chromized iron, (2) determinations of the concentration of nickel in taenite bands occurring in a fragment of meteorite from Canyon Diablo, (3) identification of intermediate phases in the as-cast structure of an alloy of titanium and copper, (4) identification of phases in the titanium—silver binary system, (5) determination of concentration fluctuations in a gold—copper alloy resulting from slow solidification, and (6) determination of the diffusion profile of nickel in single crystal sapphire.
X-Ray Diffraction Investigation of BeO Calcination Processes
Authors: Rau R.C.
Published: March 2019

To aid in the study of the preparation and properties at BeO, X-ray diffraction investigations were performed to determine the various phases and transformation temperatures occurring in the different BeO calcination processes and to determine the theoretical density of the final BeO product.

The hydroxide, sulfate, and oxalate of beryllium were the starting materials in the three calcination series. The samples studied were prepared by heating small portions of the starting materials for 1 hr at various temperatures and slow cooling. Analysis of the hydroxide series showed a direct conversion from Be(OH)a to BeO by simple loss of water. However, both the sulfate series and the oxalate series go through a series of intermediate phases in transforming to BeO. X-ray data and structure information have been obtained for most of these phases, and temperature ranges of their occurrence have been established.

Wherever possible, the X-ray results have been compared with results of stereoscopic and polarizing microscope examinations, and temperature range of occurrence have been compared with thermal balance curves.
X-Ray Diffraction Investigation of Vacuum-Deposited Metallic Films
Authors: Renius Otto
Published: March 2019

In the course of work on the vacuum deposition of metallic films, a series of X-ray diffraction investigations was run on the effects of base material orientation, heat treatment, and angle of deposition, on the structure of the deposed films. Results show that the film structure can be altered by changing several parameters during and after the deposition process. An attempt is made to correlate this structure with film adhesion and protective characteristics.
A Technique for Studying Coprecipitated Chromia-Alumina Catalysts by X-Ray Diffraction
Authors: Kehl W. L.
Published: March 2019

A diffractometer equipped with a gas proportional counter and pulse-height analyzer provides a very satisfactory means of recording the X-ray diffraction patterns of chromium-containing materials with Cu Kα radiation. The fluorescent chromium K radiation can be rejected along with much of the white background radiation without appreciable loss of Cu Kα intensity, and the advantages of copper over chromium or molybdenum radiation can be fully utilized. This is illustrated by an X-ray diffraction study of coprecipitated chromia-alumina catalysts, in which the chromium concentration varies between 0 and 37 w, %. At each chromium concentration the precipitate was studied in the washed and dried state, as well as after calcination at 500, 750, and 1400°C. X-ray diffraction patterns are presented to show the phase transformations and sample inhomogenelties that were observed.
A Study of Phase Reactions in a Complex 4.5 Al–3.5 Ti–Ni Base Alloy
Authors: Radavich John F. , Boesch W. J.
Published: March 2019

An investigation of the phase changes in a complex aluminum-titanium-hardened nickel-base high-temperature alloy was carried out after solutioning at high temperatures and aging at lower temperatures. The physical distribution and size of the precipitated phases were studied by electron microscopy. X-ray diffraction and fluorescence analyses were carried out on chemically extracted residues. The results of the xtructure changes as well as correlation of some physical properties with the structural changes are presented.
Fluorescent X-Ray Spectrographic Analyses of Amphibolite Rocks and Constituent Hornblendes
Authors: Chodos A. A. , Engel Celeste G.
Published: March 2019

Fluorescent X-ray spectrographic analyses have been made for the oxides Fe2O3 caO, MgO, K2O, TiO2, and MnO on samples of amphibolite rock. In addition, the above oxides and SiO2 and Al2O3 have been determined in a suite of constituent hornblendes from these rocks.

Classical wet chemical analyses of materials of the same minera logical composition as the samples are used to establish the working curves. This eliminates the necessity for Internal standardization or other treatment of the samples. The only sample preparation involves extremely fine grinding before analysis.

Precision of the analyses is equivalent to, or better than, that achieved by wet chemical methods.
X-Ray Spectrometric Determination of Copper, Tin, and Uranium in Bronze Heat-Treating Material*
Authors: Blank G. R. , Heller H. A.
Published: March 2019

A method is presented for the X-ray spectrometric determination of copper, tin, and uranium in a bronze heat-treating material. The method is based on the irradiation of an acid solution of the sample, to which indium and zinc have been added as internal standards. Quantitative determinations of copper and tin (each in the 40 to 60% range) are calculated from the ratios of the CuKα/ZnKα and SnKα/In Kα intensities. Uranium concentration (in the 1 to 10% range) is calculated from the ratio of the ULα/ In Kα intensities, A correction for the interference of the second-order In Kβ1,3 doublet with the first-order ULα peak is described. The over-all limits of error for single determinations at the 95% confidence level are ±0,58% copper, ±0,56% tin, and ±0,31% uranium.
Crystal Structure and Stability of Refractory Phases
Authors: Nowotny Hans
Published: March 2019

This paper deals with some recent investigations on beryllides, borides, carbides, nitrides, aluminides, and germanides of transition metals as well as with combinations of these with special reference to hafnium and uranium compounds. The results will be discussed within the general field of refractories excluding the class of typical oxides. An intense study has revealed the influence of metalloid impurities (for instance carbon, nitrogen, and oxygen on high-melting borides and silicides or nitrogen and oxygen or carbides, respectively). Very often small amounts of such metalloids introduced by preparation techniques, like hot-pressing, sintering, and powder-reaction methods may change the constitution of the system.
Some Recent Developments in the Direct Viewing and High-Speed Recording of X-Ray Diffraction Patterns
Authors: Goetze G.W. , Taylor A.
Published: March 2019

Experiments on the application of X-ray image intensifiers of the Fluorex type and of transmission-type secondary electron image intensifies (Astracon tubes) to the direct observation and recording of X-ray diffraction patterns have proved highly successful. Further improvements can be obtained by combining a Fluorex tube directly with an Astracon tube. By this means, the useful signal strength is so improved that movies at standard frame speed can be made which record the changing Laue pattern from a rotating crystal. It is shown how still further improvements are possible if the optical coupling in the system is improved by incorporating a fiber-optics window at the input of the Fluorex-Astracon tube. It is further indicated how a fiber-optics adapter can be used as an analog computer to convert the X-ray diffraction pattern from a single crystal into an exact representation of the reciprocal lattice which can be viewed directly.
Method for Finding Mass-Absorption Coefficients by Empirical Equations and Graphs
Authors: Leroux J.
Published: March 2019

A brief description of the theoretical approach of this new method is given. The main purpose of the method is to correlate in a more logical order not only the data yielding the two laws relating mass-absorption coefficient to wavelength and to atomic number, respectively, but also to delineate, within two discontinuities, the relationship existing between each value and the other ones taken as a whole. The empirical equation relating μ to λ is μ = Cλn. A table of complete values for the constant C and die power n to be assigned in the equation is given for finding the values of mass-absorption coefficients above unity for all elements (except hydrogen) and for all wavelengths between 0.17837 and 10 A. It is believed that until a complete set of experimental data obtained with modern equipment is available, this proposed method fills the enormous gaps between actual compiled values.
Use of a High-Temperature X-Ray Diffractometer to Measure the Temperature Dependence of Reflection Intensities*
Authors: Ryba Earle , Chiotti P.
Published: March 2019

The temperature dependence of the reflection intensities from copper was examined in order to determine the mean-square vibration amplitudes of the atoms in the metal. The reflections from a prealigned single crystal were examined in a Norelco diffractometer outfitted with a high-temperature chamber designed by Chiotti. The intensities of the (400) reflection for copper were measured at temperatures from 13 to 1000°C. Difficulty was experienced in obtaining reproducible intensity measurements, and it is suggested that this was due to changes in the mosaic structure of the single crystal during thermal cycling.
Microanalysis with Ultrasoft X-Radiations*
Authors: Henke Burton L.
Published: March 2019

The diffraction, reflection, absorption, fluorescence, and the electronic emission that results from the interaction with ultrasoft X-rays (λ > 10 A) are presented as practical bases for microanalysis. Recent developments on sources and detectors for the ultrasoft X-radiations are described. A preliminary report on a current investigation on low-energy photo-Auger electron analysis and on a new type of low-energy electron spectrometer is also presented.
The Geometrical Representation of Ternary Alloys and its Applications to X-Ray Fluorescence and Microprobe Analysis
Authors: Taylor A. , Kagle Brenda J. , Beiter E. W.
Published: March 2019

A simple and accurate graphical method is described for converting the composition of ternary alloys from weight per cent to atomic per cent, and vice versa. By making certain simplifying assumptions, the principles of the method are extended to the approximate determination of ternary alloy compositions from the count fractions obtained from fluorescence X-ray spectra. An example is given for the not-so-favorable system bismuth-germanium-tellurium. On account of the simpler excitation conditions, the same procedures may also be applied to X-ray microprobe analysis.
A Test of the Precision and Sources of Error in Quantitative Analysis of Light, Major Elements in Granitic Rocks by X-Ray Spectrography
Authors: Baird A. K. , MacColl R. S. , McIntyre D. B.
Published: March 2019

Quantitative analysis of major elements (Na, Mg, Al, Si, K, Ca, Ti, and Fe) in rocks by classic wet-chemical procedures, in addition to being a costly and laborious process, has been shown to be subject to significant errors. Mineralogists and petrologists, increasingly concerned with determining small elemental differences in rock bodies, have turned to more rapid and precise methods in the field of spectral analysis. The development of X-ray spectrographic techniques in the light-element range has therefore been of particular interest. This paper summarizes the results of a test of the precision and sources of error in the X-ray method as applied to major elements in granitic rocks.

The test, using commerically available equipment and the fusion technique of specimen preparation, was designed for a five-way, completely nested variance analysis. Sources of variance are (1) different lengths of fusion time, (2) replications of a single fusion time, (3) replications of briquetting the fused specimens, (4) replications of individual runs in the spectrograph, and (5) replications of individual spectrograph readings of the Kα line intensity. A total of 64 readings per element were obtained and the significance of each factor tested for each element. Greatest sources of error are shown to be in factors 2 and 4. The total variance for each element is expressed as per cent relative deviation of counts per second. Calibration curves of natural and synthetic granitic rocks, fused with dilutions ranging from 13 to 36% rock in borax, provide conversions from relative deviation in counts per second to relative deviation in weight per cent. These values indicate that the precision of the X-ray method is directly comparable with wet chemistry for Si, probably better for Al, and distinctly superior for K, Ca, Ti, and Fe. Of the major rock-forming elements only Na and Mg are presently beyond the scope of the fusion method.
Factors Governing the Structure of Intermetallic Phases
Authors: Laves F.
Published: March 2019

A review of the crystal structures of the elements shows some prevailing tendencies of atomic arrangement. These are discussed as space, symmetry, and connection principles. Counteracting temperature and bond factors can be recognized.

The same principles and factors are responsible for the formation of alloy structures, taking into account additional factors due to the component's similarities and dissimilarities in size and electronegativity.

Similarity favors solid solution and dissimilarity favors compound formation. A q compound is here defined as a phase in a q-component system not connected with any other phase of the system by continuous solid solution. Similarly a q structure is defined as a structure type which needs only q components to be formed (considering present-day knowledge). For example, the binary compound Mg17Al12 has the elementary (1 ™) structure of α-manganese. As a rule, q compounds tend to form p structures with q > p.

A discussion of q structures with q = 1, 2, and 3 is given in some detail on the basis of known representatives to show: (1) the competition of geometrical principles and physicochemical factors in determining atomic arrangements of alloys; and (2) the value of rules for making guesses on the probable occurrence of compounds and their chemical composition in polycomponent systems yet unknown.
The Zirconium-Iron System
Authors: Rhines F. N. , Gould R. W.
Published: March 2019

By means of a combined X-ray diffraction and metallographic study, two heretofore unrecognized phases, Zr4Fe and Zr2Fe, have been identified. Approximate verification of this finding has been made by Dr. David Levinson, using microprobe analysis. A tentative revision of the Zr-Fe phase diagram is proposed.
The Effect of Cold-Work on the X-Ray Diffraction Pattern of a Copper-Silicon-Manganese Alloy
Authors: Welch D. O. , Otte H. M.
Published: March 2019

Plastic deformation of metals produces a state characterized by the presence of residual elastic strains, small domains which diffract X-rays coherently, and often stacking faults; these effects may be studied with X-ray diffraction techniques. Changes in the lattice parameter, shifts in the relative positions of diffraction lines, and the broadening of diffraction lines were used to study the state of coldwork resulting in Cu-6.6 at.%Si-1.2 at.%Mn after deformation by filing, wiredrawing, and uniaxial tension at room temperature.

Both filing and wire-drawing produce large root-mean-square strains and stacking faults, whereas deformation by tension up to 22% extension fails to produce any clear evidence of faulting or root-mean-square strains. Tensile deformation causes fragmentation of coherent domains to an average dimension of 250 Å after 22% extension, and results in a radial, tensile, residual macrostrain arising from a smaller rate of work hardening in the surface layers than in the interior. Wire drawing also results in a residual macrostrain system. Deformation appears to enhance diffusion and promote solute clustering at room temperature.
The Daily Use of a Basic Norelco X-Ray Spectrograph in an Aluminum Reduction Laboratory
Authors: Eastman W. B.
Published: March 2019

Three basic methods for the daily use of the X-ray spectrograph are presented with the object of demonstrating simplicity of operation, reliability of results, and ease of use of the basic Norelco X-ray spectrograph by personnel not highly trained in the operation of such equipment. The methods to be outlined briefly are: (1) Determination of calcium fluoride in reduction cell electrolyte; (2) Analysis of cast iron for Si, P, Mn, S; find (3) Analysis of carbon materials for S, K, Ca, V, Mn, Fe, and Ni. The mechanics of the methods will be outlined with the reasons for their selection, and the operating and maintenance problems which have been encountered will be discussed.
Sodium and Magnesium Fluorescence Analysis—Part I: Method
Authors: Henke Burton L.
Published: March 2019

As is well known, the fluorescent yield decreases very rapidly with the atomic number with the result, for example, that sensitive sodium and magnesium analysis is extremely difficult if not impossible with conventional X-ray spectrographs. It is demonstrated, however, that analysis for sodium and magnesium can be accomplished with sensitivity comparable to that conventionally obtained for elements such as aluminum, silicon, and phosphorous, providing that the conditions for excitation and measurement of the associated soft X-radiations are optimized, A high-intensity demountable tube using an aluminum anode has been developed which can be used interchangeably with the conventional spectrographic X-ray source. This provides a large amount of incident radiation, aluminum foil filtered, optimally close in wavelength to that of the line radiation being excited. A gypsum analyzing crystal is used along with greatly reduced beam collimation. The standard flow proportional counter and pulse height discrimination is employed. An appropriate filter, such as aluminum foil, is used as a window for the counter1 to provide further discrimination and enhanced signal-to-background ratio.
The Atomic Order in Guinier-Preston Zones of Aluminum-Silver Alloys
Authors: Gerold Volkmar , Auer Heinz , Merz Winfried
Published: March 2019

The formation of the spherical Guinier—Preston zones in an aluminum-silver alloy is governed by a metastable miscibility gap, which consists of two different sections. The lower section occurs below 170°C (η state), the higher section up to 420°C (∊ state). The zones in the two sections differ in their silver concentration and in their atomic order. To prove the change in order, a combination of X-ray small-angle scattering and electric resistivity measurements was used. As the resistivity depends on the zone size and the atomic order, the change in order can be found when the zone size is known. This size was measured by the X-ray technique. To complete the results, X-rays ingle-crystal diffraction patterns with monochromatic radiation were taken at different stages. According to these patterns, three different states must be distinguished.

The η′ state exists at room temperature after quenching from 550°C. The silver atoms prefer a layered arrangement in the zones, which is not very stable. It is destroyed after short annealings above 100°C. The η state is developed during annealing below 170°C. A three-dimensional atomic order is built up with increasing zone size, which results in a marked decrease in the resistivity. For the ∊ state (above 170°C), a nearly random atomic distribution exists. Step-quenching experiments prove that the ordered η state can also be developed at room temperature.
An Explanation of Microstructures in the Tantalum-Carbon System
Authors: Santoro G. , Probst H. B.
Published: March 2019

Compositions in the tantalum-carbon system were prepared by carburizing high-purity tantalum wires. The microstructures so produced exhibit regions of a characteristic striated structure identical to those observed by earlier investigators. There are disparities in the literature as to the origin of such structures in the tantalum—carbon system. They have been variously described as “twins,” “striated structure,” “precipitate,” and “structure of unknown origin.” This paper presents conclusive evidence that the structures in question are the result of precipitation on cooling. In addition, a coherent precipitation model is applied in which it is shown that the lattice relationship {0001}Ta2C‖{Klll}TaC can exist with less than 0.5% misfit. This relationship is shown to completely explain the occurrence and characteristic appearance of the observed micro structures. Correlations between chemical analysis, X-ray diffraction results, metallography, and microhardness measurements confirm the proposed precipitation model.
Depth of Saw and Lap Damage in Germanium
Authors: Knudsen John F.
Published: March 2019

A study utilizing an application of X-ray diffraction analysis has been made to determine the depth of surface damage in s ingle-crystal wafers of germanium. Damage was introduced by mechanical lapping and sawing. A scintillation-counter double-crystal diffractometer system was used with a 3-m evacuated collitnator. This experimental arrangement employed the (220) reflection, from a silicon monochromator, using Cu Kα1 radiation. All wafers were taken from dislocation-free crystals which were subsequently centerless ground, sawed, lapped, and etched. Half-widths were determined for the sawed and lapped conditions. Successive etchings were used to remove the damaged surface layer with the resulting halfwidths being plotted as a function of thickness removed and etching time.

The depths of damage—8.0 ± 0.7 μ for sawing and 3.0 ± 0.7 μ for lapping—were indicated by the depth at which the line breadth measurements reached a limiting value. For crystals used in this study, the median value for this limiting half-width was 28″. The experimental data expressing the rate of etching indicates the presence of two separate rates—one for the damaged material and one for the undamaged substrate. An unexpected finding is a faster etch rate for the undamaged material than that observed for the damaged layer. Quite good correlation is obtained between the depth of damage as determined by X-ray and etching techniques.
Interrelationships of Sample Composition, Backscatter Coefficient, and Target Current Measurement
Authors: Heinrich Kurt F. J.
Published: March 2019

The use of target current measurements in the electron microprobe for quantitative analysis of binary samples has been proposed by several authors. However, the equations proposed for calculations as well as instrumental conditions differ considerably. The present paper relates the target current measurements made with the Applied Research Laboratories microprobe to the backscatter coefficients determined independently. Equations for analyzing binary samples as well as applications to line scans and concentration mapping are given.
A Comparison of the Performance of Gratings and Crystals in the 20-115 Å Region*
Authors: Nicholson James B. , Wittry David B.
Published: March 2019

Two aluminized gratings with different blaze angles, 1° and 7.55′, and a barium stearate monolayer crystal were compared for first-order X-ray line spectra from oxygen (23.707 Å) to beryllium (113 Å). The peak intensities for the gratings were found to be greater than for the monolayer crystal when the same detector, source, and excitation conditions were used. Line-to-background ratios and halfwidths were comparable.
Evaluation of a Demountable X-Ray Tube Vacuum Spectrograph for the Determination of Low-Atomic-Number Elements
Authors: Thatcher John W. , Campbell William J.
Published: March 2019

The fluorescent excitation of long-wavelength X-ray spectra is reviewed with respect to X-ray tube target element, inherent filtration, and optimum kilovoltage. A demountable X-ray tube vacuum spectrograph designed for the determination of the light elements is described. Operation of this instrument with both secondary and combined primary—secondary excitation is evaluated. Examples from the literature are cited to show the feasibility of direct electron excitation of longwavelength spectra.
The Design and Performance of the Dual-Function Spectrodiffractometer and Automatic Programmer
Authors: Ashby W. D. , Buhrke V. E. , Patser G. V.
Published: March 2019

A new concept in a dual-function diffractometer-spectrometer has been developed. With this new concept, it is unnecessary to disassemble any part of the instrument when changing from diffraction to air-helium spectroscopic applications and vice versa. Therefore, the alignment of the instrument is not disturbed and changeover is accomplished in a matter of seconds.

The diffractoraeter is the standard biplane diffractometer, having an angular range of −55 to +164° 20 and a full 360° ω. Without interfering with the entire angular range of the diffractometer, the spectrometer section allows an angular range to 154° 2θ, This uninterrupted freedom of angular motion for both functions is accomplished by the design concept of using different frames of reference for the 0-180° 2θ plane of the diffractometer and the 0-180° 2θ plane of the spectrometer. In one case, the motion of 16 toward higher positive angles is counterclockwise and in the other case, it is clockwise. The frames of reference are displaced by 96°.

The helium attachment for low-atomic-mimber elements ensures complete replacement of the air with helium in a flushing time of 15 sec. After changing samples, the helium atmosphere returns to equilibrium within 5 sec.

A ten station programmer also has been developed, enabling one to automatically program oscillating scans and stepped scans of diffraction profiles as well as sequential emission analyses. The angular position is programmed in increments of 0.01° and is reproducible within 0.005°.

During the sequential mode of operation, 20 is driven to the next position at a rate of 40 deg/min. In addition, stepping increments as small as 1/120° and scanning speeds of ⅛, ¼, ½, 1, and 2 deg/min are available. In all of the above modes of operation, data are collected and printed as a function of preset time, preset count, or angular position.

In this paper, typical performance characteristics and applications are presented.
Experimental X-Ray Stress Analysis Procedures for Ultrahigh-Strength Materials
Authors: Woehrle H. R. , Reilly F. P. , Barkley W. J. , Jackman L. A. , Clough W. R.
Published: March 2019

Quite recently there has been commercially developed a series of high-alloy steels, on new compositional bases, which possess 3 very desirable combination of unusually high strength, good ductility, and toughness even at comparatively low temperatures. At the same time, research with mechanical working procedures, combined with optimum heat-treat considerations, have produced with several older, more conventional steels, strength levels of high orders of magnitude. Each of the considered materials is capable of yield strengths approaching or exceeding 300,000 psi, corresponding to elastic strains of about 1%.

This paper is concerned with the development and evaluation of workable X-ray stress analysis procedures to be employed to measure, with a good degree of accuracy, high elastic strains. The materials selected include maraging steels, ausformed steels, and cold-drawn A.I.S.I. 4340 steels.

Of the various possible X-ray techniques which were considered, very satisfactory results were obtained by the use of the two-exposure method. A special fixture was designed and constructed to allow uniaxial straining of test specimens while in the X-ray unit. Imposed strains were measured directly by strain gauges mounted on tbe specimen. Simultaneously, strains were measured by the use of chromium radiation filtered with vanadium foil. The peak resolution obtained was very satisfactory with a peak to background ratio of approximately 4:1 for the {211–121} martensite doublet used to measure the shift in peak location between the normal and oblique exposures. Because of the widths of the peaks involved, it is impossible to precisely specify the angular position of a given peak by inspection of the usual recorded trace. A counting technique, combined with a least-squares curve-fitting procedure involving five points, was very satisfactory for precisely locating positions of maximum intensity, Superior results were obtained when a multiplicative correction factor proposed by Koistinen and Marburger was applied.
An Ultrahigh-Temperature, Single-Crystal Texture Camera Diffractometer*
Authors: Prickett Robert L.
Published: March 2019

A single-crystal high-temperature X-ray camera has been built with permissible operating temperatures of 2500°C. The camera is constructed to rest upon a Siemens horizontal diffractometer and may be used with either an external electronic detector or with film. The sample is supported on an externally adjustable goniometer head and is heated from the back by an ion beam. Controlled oscillation allows rotation photographs to be obtained from the sample surface not touched by the ion stream. Temperature is controlled by a thermocouple supporting the sample, the thermocouple being an intrinsic part of the goniometer. As a design limit, zero and first order layer lines with iron Kα. radiation on specimens with lattice parameters of 2.6 Å or larger may be recorded. Copper, cobalt, and molybdenum radiation allow even greater latitude. Types of samples that may be studied include powder (pellet), single crystal, wire, or rod. The camera serves equally well for single-crystal, texture, or powder studies on refractory materials.
Diffraction Maxima Positions in Two Types of Liquid Organosilicon Compounds
Authors: Stammler M. , Bruenner R. , Orcutt D.
Published: March 2019

A study of two homologous series of liquid oiganosilicates showed a position change of the diffraction maximum of the halo. The first series consisted of polymeric silicic acid esters of the general formula SinOn-1(OC2H5)2n+2 with the following arrangement, where n = 1,2,3,…

For these compounds, an increase of the d-spacings was observed with increasing length of the –Si–O–Si– chain. The d-spacings observed require coiled molecules.

The second series consisted of orthoesters of silicic acid with the general formula Si(OR)4, where R is the aliphatic hydrocarbon chain. Here, an increase of the d-spacings was observed with increasing number of carbon atoms in the hydrocarbon chain. The molecules have close to spherical symmetry. The hydrocarbon chains provide a very efficient shielding of the [SiO4] tetrahedra, so that only very little intermolecular interference occurs. A similar relation exists also for the refractive indices of these compounds which increase with increasing length of the –Si–O–Si– chain in Series 1 and with increasing number of carbon atoms in Series 2. A plot of silicon concentration vs. d-values or refractive index shows both minimum values for ethyl orthosilicate.

D. B. Nash could show that for silicate glasses, the d-values increased with increasing SiO2 content. For liquid organosilicon compounds, not the silicon content but the size of the molecule (total number of atoms except hydrogen) is responsible for both the change of the d-values and the refractive indices. The size of the “ordered regions” in these liquids is related to the size of the molecules only. The interaction of molecules is minimized by the shielding effect of the organic groups,
Some Instrumental Considerations in the Automatic On-Stream Analysis of Pulps for Elemental Content
Authors: Moffat Walter G. , Carson Robert
Published: March 2019

This paper describes the detailed assembly of an X-ray automatic analyzer for the continuous estimation of elemental contents in flowing pulp streams as applied in a concentrator of the Northern Rhodesian Copperbelt. Arguments are given for the selection of electronic components, the programming of operations, mechanical movements, and other aspects concerned with the consecutive analysis of a number of pulp streams of widely different composition and elemental concentration. Details are given of a method of automatic compensation for pulp density and matrix variations using X-ray absorption.
Some Observations on X-Ray Emission as a Function of Accelerating Voltage in the Microprobe
Authors: Burk D. L.
Published: March 2019

Data are presented from several systems for which the emitted X-ray intensity goes through a maximum as accelerating voltage is increased. An attempt is made to systematize the data in terms of absorption, wavelength, and atomic number. A very simple model, analyzed graphically, is capable of displaying many of the features of the experimental data.
A Modification of the Scanning X-Ray Topographic Camera (Lang's Method)
Authors: Yoshimatsu Mitsuru , Shibata Atsushi , Kohra Kazutake
Published: March 2019

A modification of the scanning X-ray topographic camera, is reported. The specimen and photoplate are traversed back and forth independently in two directions rather than in the same direction as in the case of Lang’s camera. The distortions of the photographs caused by geometrical arrangement can be eliminated through this construction so as to have a one-to-one correspondence. Examples of reflection photographs as well as transmission photographs are shown. Some of them are compared with those taken using Lang’s camera. The dislocation images in the reflection photographs show a good one-to-one correspondence to those in the transmission photographs. The broadening of the dislocation images in the traversing direction is discussed. The present camera is especially useful for the studies of lattice defects in the thick specimens because the reflection photographs can be easily taken.
An X-Ray Diffraction Study of the Phase Transformation Temperature of MnO
Authors: Gazzara Charles P. , Middleton R. M.
Published: March 2019

X-Ray diffraction measurements of MnO confirm the hypothesis that the structural temperature and the magnetic transition temperature, or Néel temperature) are the same. The usefulness of X-ray diffraction intensity data of MnO, with respect to an atomic structural refinement problem involving α-Mn powders, is discussed. Lattice constant values of MnO are listed between 100 and 310°K
High-Intensity Rotating Anode X-Ray Tubes
Authors: Taylor A.
Published: March 2019

Demountable rotating anode X-ray tubes with a 7½ kW power dissipation have been built for conventional diffraction work with powder cameras and equi-inclination Weissenberg goniometers, and for use with a tetrahedral press for studying crystalline matter at ultra-high pressures. The tubes employ a highly compact cooling and sealing arrangement on the rotating anode which enables four windows to be used with the focal spot close to the specimen. A rotational speed of 1750 rpm with a focal spot size of 10 × 1 mm enables the tubes to be operated at 250–275 mA at 30 kV DC or at 150 mA, 50 kV DC.
A Dual Counter X-Ray Analyzer for the Rapid Quantitative Analysis of Two-Phase Systems
Authors: Sanderson B. S. , MacCardle L. E.
Published: March 2019

The normal procedure for a quantitative measurement of two phases with an X-ray diffractoraeter is to scan or count the intensities of two diffraction peaks and then to calculate the ratio of the two phases using an appropriate equation. This paper will describe an improved method of quantitatively measuring two phases in a sample. The diffractometer, which was constructed by Philips Electronics Instruments, consists of two fixed scintillation counters mounted at the Seeman-Bohlin focusing positions for the two desired diffraction lines. Each counter is preceded by a lithium fluoride curved crystal monochromator. The output from each counter feeds to a separate sealer which can be arranged to gate both sealers at a preselected number of counts. At this point a tape printer prints out the counts for both sealers. These counts are then related to the proportions of each phase present by an appropriate equation. Most of the electronics are solid-state designs. This paper will describe the instrumentation and show how it can be used to measure rapidly and precisely the ratio of anatase to rutile in a titanium dioxide system. The savings in time over the conventional method can be as much as 100 to 1.
Determination of Electron Distribution and Bonding from Soft X-Ray Emission Spectroscopy
Authors: Holliday J. E.
Published: March 2019

From measurements of the shift in wavelength with chemical combination, it appears there is very little transfer of charge between the metal and nonmetal atoms for the Group-IV transition-metal carbides and diborides. For Group-VI transition-metal carbides and beyond, there appears to be a definite transfer of charge from the carbon to the metal atom. The bonding in the Group-IV transitionmetal carbides is largely co valent, and metallic for the Group-IV transition-metal diborides. A comparison of shapes of emission bands with crystal structure indicates that, in general, NaCl-type structures have symmetrical peaks with narrow bandwidths compared to hexagonal structure, which have asymmetrical peaks, broad bandwidths, and long tails to the bottom of the bands.
X-Ray Techniques in the 1 to 400 Å Range
Authors: Sterk Andrew A.
Published: March 2019

X-ray work in the 10 to 400 Å range usually requires, for maximum sensitivity, new methods of X-ray generation, analysis, and detection. A comparative survey includes X-ray generation by fluorescence, electron bombardment, and proton bombardment. Dispersive analysis with crystals and gratings is described. Finally, window less photoelectric multipliers are evaluated as X-ray detectors.

Results show that typical efficiences range from 10−4 to 10−2 photons/electron or photons/proton, with the latter value as a practical upper limit. An efficiency of 8.5% has been measured for a KAP crystal covering the wavelength range up to 25 Å, while an original gold-plated grating lias a maximum measured efficiency of 20%. Counter efficiency may range from 1 to 50%, depending on wavelength. Total efficiency for a grating-type spectrometer in the 20 to 400 Å range has been measured to 2 × 105 photons/cm2-count.
On the Primary X-Ray Analyzer
Authors: Kimoto Shizuo , Sato Masayuki , Kamada Hitoshi , Ui Takuzi
Published: March 2019

The primary X-ray analyzer is used for nondestructive spectrochemical analysis of solid specimens. Accelerated electron beams bombard the specimen surface directly and generate primary X-rays which are measured in a vacuum spectrometer. The method of primary X-ray spectroscopy is superior to the fluorescence X-ray spectroscopy because (1) detectable sensitivity for such light elements as magnesium and aluminum is very high, and (2) the correction of the measured value for self-absorption of X-rays by the specimen itself is low. The performance of the instrument and applications are reported.