scholarly journals The secondary cathode rays expelled from metals by molybdenum K α radiations

1935 ◽  
Vol 149 (868) ◽  
pp. 587-595 ◽  
Keyword(s):  
Magnetic Field ◽  
Recent Work ◽  
Photoelectric Effect ◽  
Specific Charge ◽  
Secondary Electrons ◽  
X Ray ◽  
A Value ◽  
The Mean ◽  
The Absolute ◽  
Gold Platinum

Kretschmar has recently described a series of accurate measurements of the energies of the electrons expelled by molybdenum K α 1 radiations from targets of gold, platinum, silver and copper. He deduced his electron energies from deflections in an accurately known magnetic field, and it is obviously important to compare his results with those of similar recent work in which other primary radiations (copper and chromium K-rays) were used to excite secondary electrons from the same targets. Kretschmar applies his results to the deduction of a value for the specific charge, e / m 0 , of the electron. In doing this he has to assume a value for e / h , as well as values of X-ray wave-lengths. He eliminates part (not all) of the effect of uncertainty in the absolute values of the wave-lengths by using the X-ray (inverse photoelectric effect) value for e / h . He takes, in fact, e / h = 7·2796 × 10 16 e. s. u. erg -1 sec -1 —the mean of the values given by Duane, Palmer and Yeh and by Feder. He then deduces, as the mean result of his own deflection experiments, 1·757 × 10 7 e. m. u. gm -1 as the most probable value of e / m 0 .

Elaboration, Structure and Mössbauer Spectroscopy of Nanostructured Fe100−xSix Powders Elaborated by Mechanical Alloying

SPIN ◽  
2017 ◽  
Vol 07 (02) ◽  
pp. 1750002 ◽  
Author(s):  
M. Hemmous ◽  
A. Guittoum
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Mechanical Alloying ◽  
Hyperfine Magnetic Field ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Mean ◽  
Xrd Studies

We have studied the effect of the silicon concentration on the structural and hyperfine properties of nanostructured Fe[Formula: see text]Six powders ([Formula: see text], 20, 25 and 30[Formula: see text]at.%) prepared by mechanical alloying. The X-ray diffraction (XRD) studies indicated that after 72[Formula: see text]h of milling, the solid solution bcc-[Formula: see text]-Fe(Si) is formed. The grain sizes, [Formula: see text]D[Formula: see text] (nm), decreases with increasing Si concentration and reaches a minimum value of 11[Formula: see text]nm. We have found that the lattice parameter decreases with increasing Si concentration. The changes in values are attributed to the substitutional dissolution of Si in Fe matrix. From the adjustment of Mössbauer spectra, we have shown that the mean hyperfine magnetic field, [Formula: see text]H[Formula: see text] (T), decreases with increasing Si concentration. The substitutional dependence of [Formula: see text]H[Formula: see text] (T) can be attributed to the effect of p electrons Si influencing electrons d of Fe.

scholarly journals The Parallaxes of U Gem Variables

1979 ◽  
Vol 53 ◽  
pp. 494-494
Author(s):  
Karl W. Kamper
Keyword(s):  
Confidence Level ◽  
Absolute Magnitude ◽  
Weighted Mean ◽  
Quiescent Phase ◽  
A Value ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

An Allegheny parallax series of SS Cyg, consisting of 52 exposures obtained on 15 nights, was recently measured on the PDS microphotometer at the David Dunlap Observatory, and a value of (m.e.) derived for the absolute parallax. This is close to the mean of the two previous discordant measures for this star given in the table below. The weighted mean of the three determinations implies that the absolute magnitude, at quiescent phase, of the star is between 7.0 and 9.0 formally at a 90% confidence level. Recent parallax determinations made at Lick by Vasilevskls et al. (1975) for three other stars, listed below along with the Mt. Wilson value for U Gem, imply even fainter absolute magnitudes.

Identification of iron-containing impurities in natural kaolinites using the Mössbauer effect

1975 ◽  
Vol 40 (309) ◽  
pp. 89-96 ◽  
Author(s):  
C. S. Hogg ◽  
P. J. Malden ◽  
R. E. Meads
Keyword(s):  
Magnetic Field ◽  
Hyperfine Field ◽  
Mössbauer Effect ◽  
Hyperfine Magnetic Field ◽  
Mossbauer Effect ◽  
X Ray ◽  
Chemical Work ◽  
Superparamagnetic Behaviour ◽  
The Mean ◽  
Mössbauer Data

SummaryTwo clay samples originating in the kaolinized granite area near St. Austell, Cornwall, have been examined by Mössbauer spectroscopy. The iron-containing impurity in the sample with a red discoloration (sample A) has, by measurement of the hyperfine magnetic field, been identified as hematite. In the case of sample B, which was yellow in colour, preliminary Mössbauer work indicated β-FeOOH as the impurity, but detailed measurements of hyperfine field and Nöel temperature, when compared with similar results for a synthetic β-FeOOH sample, suggested otherwise. X-ray and chemical work suggested that the iron-containing phase in sample B is goethite, α-FeOOH in which some substitution of Al+3 for Fe3+ has occurred; the Mössbauer data are consistent with this conclusion. Both clay samples exhibited superparamagnetic behaviour and this has been utilized to obtain rough estimates of the mean radius of the particles of the iron-containing impurity. These were 117 Å for the α-Fe2O3 in sample A and 270 Å for aluminian α-FeOOH in sample B.

Magnetic Structure and Properties of the Intercalated Compound Fe0.5TiSe2

2010 ◽  
Vol 168-169 ◽  
pp. 157-160 ◽  
Author(s):  
N.V. Baranov ◽  
N.V. Selezneva ◽  
Valery G. Pleshchev ◽  
N.V. Mushnikov ◽  
V.I. Maksimov
Keyword(s):  
Magnetic Field ◽  
Crystal Structure ◽  
Electrical Resistivity ◽  
Neutron Diffraction ◽  
Magnetic Moments ◽  
Structure And Properties ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Monoclinic Crystal Structure ◽  
A Value

The intercalated compound Fe0.5TiSe2 has been studied by means of X-ray, neutron diffraction, electrical resistivity and magnetization measurements. This compound with Fe atoms located between Se-Ti-Se sandwiches has a monoclinic crystal structure and exhibits a long-range antiferromagnetic (AF) ordering below TN = 135 K. At T < TN, the Fe magnetic moments with a value ~ 3.0 µB are directed at an angle of (74.4±0.5)º to the layers and form a tilted antiferromagnetic structure with the propagation vector (½, 0, ½). It has been shown that application of magnetic field above 300 kOe may lead to transformations of the AF structure.

A study of the isotopic abundance of boron from various sources

1968 ◽  
Vol 5 (4) ◽  
pp. 921-927 ◽  
Author(s):  
E. K. Agyei ◽  
C. C. McMullen
Keyword(s):  
Boric Acid ◽  
Atomic Weight ◽  
Igneous Rocks ◽  
Tokyo Bay ◽  
Standard Errors ◽  
Isotopic Ratios ◽  
Isotopic Abundance ◽  
A Value ◽  
The Mean ◽  
The Absolute

The absolute ratio of 11B/10B has been determined for boron from different terrestrial sources with a precision of 0.2% (two standard errors) and a reproducibility of 0.2% (half-range). Values fall in the range 4.108 to 3.987 (i.e. 3% variation) and give a corresponding range in the boron atomic weight of 10.814 to 10.810 (0.04% variation). The absolute ratios are 7% lower than those reported by early workers, but are in accord with the results of recent investigations. Igneous rocks and boric acid are found to have high isotopic ratios, whereas Tokyo Bay water possesses a value for 11B/10B near the mean.

Structural Change and Magnetic Properties of Mechanically Alloyed Spinel Ferrite CoFe2O4

2020 ◽  
Vol 855 ◽  
pp. 108-116
Author(s):  
Novrita Idayanti ◽  
Dedi ◽  
Azwar Manaf
Keyword(s):  
Magnetic Properties ◽  
Sintering Temperature ◽  
Spinel Ferrite ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
A Value ◽  
Hall Plot ◽  
Crystallite Sizes ◽  
The Mean

Magnetic property studies and the crystallite structures evolution of spinel ferrite CoFe2O4 particles are reported in this paper. The ferrite was prepared through mechanical milling of all alloy precursors and sintered at various temperatures of 800, 900, 1000, and 1100 °C to promote the crystalline structure. X-ray diffraction (XRD) and Williamson-Hall plot were used to calculate the mean crystallite size and microstrain. Changes in the microstructure and crystallite sizes were occurring due to sintering treatments. It is found that the remanence (Mr) and saturation magnetization (Ms) increase with increasing sintering temperature, but a decrease occurred only at the temperature of 1100 °C. The optimum magnetic properties were obtained in a sample sintered at 1000 °C with a value of Mr = 36.00 emu/g and Ms= 74.05 emu/g.

scholarly journals IV. A determination of the electromotive force of the weston normal cell in semi-absolute volts

1914 ◽  
Vol 214 (509-522) ◽  
pp. 147-198 ◽  
Keyword(s):  
Electromotive Force ◽  
Order Of Accuracy ◽  
Absolute Determination ◽  
A Value ◽  
Great Progress ◽  
The Mean ◽  
The Absolute ◽  
The Times ◽  
Made In

The measurement of the E. M. F. of the Weston cell affords the best means of comparing the performances of different methods and instruments for the absolute determination of the ampere. Great progress has been made in the last six years, but the most recent determinations by independent methods, giving equal promise of accuracy, still show discrepancies covering a range of 2 parts in 10,000, which must be debited for the most part to the difficulty of the absolute determination of current. Each method in itself appears to give an order of accuracy of repetition approaching, or even exceeding, 1 in 100,000. It is therefore of special interest and importance to compare the results of methods differing as widely as possible in experimental details in endeavouring to arrive at a value comparatively free from the constant errors which may beset any particular type of method. The measurements described by Mr. Shaw in the following paper were made by the method of the Weber bifilar electrodynamometer, as modified by Clerk Maxwell and Latimer Clark, which has not hitherto been employed for work of the highest accuracy, and which merits attention on account of its many fundamental points of difference from recent methods. The instrument originally supplied to McGill College for this purpose was a faithful copy of Clerk Maxwell’s instrument at Cambridge, of which the theory is given together with a figure and description in his ‘ Electricity and Magnetism,’ vol, 2, p. 367. The chief sources of error in this instru­ment were (1) the uncertainty of insulation of the coils, which proved to be of the order of nearly one half of 1 per cent.; (2) the difficulty of determining the mean radii of the coils, which were wound with silk-covered wire; (3) the want of rigidity of the pulley arrangement for equalising the tensions of the suspending wires, and the imperfect elasticity of the control, which depended too much on torsion, and made it impossible to obtain readings consistent to 1 in 1000 for the deflections or the times of oscillation. These defects were so fatal to accurate work even of the order of 1 in 10,000, which was all that it was originally contemplated, that it was found necessary to reconstruct the instrument entirely until nothing remained of the original except the frame, and even that required stiffening to a material extent.

scholarly journals X-ray electrons expelled from metals by silver K α 1 radiations

1940 ◽  
Vol 176 (964) ◽  
pp. 28-33 ◽  
Keyword(s):  
X Ray ◽  
Planck’S Constant ◽  
A Value ◽  
Planck's Constant ◽  
Gold Platinum

The energies of the X-ray electrons expelled from targets of gold, platinum, silver and copper by silver K α 1 rays have been measured in the magnetic spectrograph. The results have been combined with those of earlier measurements, and they yield a value for Planck’s constant of 6.62 9 x 10 -27 erg sec.

The Zeeman effect in interstellar clouds

1967 ◽  
Vol 31 ◽  
pp. 385-389 ◽  
Author(s):  
G. L. Verschuur
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Zeeman Effect ◽  
Longitudinal Component ◽  
Interstellar Clouds ◽  
A Value ◽  
Upper Limit ◽  
The Mean ◽  
Cas A ◽  
Spiral Arm

The interpretation of Zeeman-effect measurements in terms of interstellar magnetic fields is strongly involved with the problems of the nature of interstellar clouds, and of their relationship to the structure of the field. The best measurements furnish, for the mean longitudinal component of the spectrum of Tau A, a value of + 1·1 ± 3·0 μG (micro-gauss), and for that in the Orion-Arm feature in Cas A, - 0·8 ± 3·5 μG. These values are consistent with an upper limit of 7 μG to a uniform magnetic field, pervading the absorbing clouds and directed parallel to the local spiral arm.

scholarly journals Comparative Evaluation of the Presence of Insertion Enthesophyte in the Achilles Tendon by X-Ray and Magnetic Resonance Imaging: Intra and Inter Observer Reliability

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0011
Author(s):  
Tiago S. Baumfeld ◽  
Thiago A. Silva ◽  
Wilel A. Benevides ◽  
Dário M. Silveira ◽  
Daniel Baumfeld
Keyword(s):  
Magnetic Resonance ◽  
Interobserver Reliability ◽  
Magnetic Resonance Images ◽  
Kappa Index ◽  
Interobserver Reproducibility ◽  
X Ray ◽  
A Value ◽  
Insertional Tendinopathy ◽  
Entire Thickness ◽  
The Mean

Category: Other; Sports Introduction/Purpose: To evaluate the intra and interobserver variation on the presence of enthesophyte in patients with Achilles insertional tendinopathy and the clinical radiological correlation of x-ray (X-ray) and magnetic resonance images (MRI). Methods: We selected Lateral X-ray images of the calcaneus and videos of ankle MRI in which we showed the entire thickness of the calcaneus in the coronal, sagittal and axial views, in both T1 and T2 weightings, of 20 patients with Achilles insertional tendinopathy. 5 foot and ankle surgeons and 5 musculoskeletal radiologists, with varied experience time, analysed the images. Intra and Interobserver correlations were studied with the kappa index. Results: The average Ƙ intraobserver of the results of the MRI analyzes was 0.49, and the average Ƙ interobserver of the results of the MRI analyzes was 0.47. The mean Ƙ intraobserver values of the results of the X-ray analyzes were 0.61, while the Ƙ interobserver had a value of 0.60. We also observed that the group of less experienced surgeons and radiologists showed a worse Ƙ intraobserver than the more experienced ones. Conclusion: The values are in agreement with previous studies, confirming moderate intraobserver and interobserver reproducibility in MRI exams and good or substantial interobserver and interobserver reliability in X-ray exams.

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