Computational investigations of mechanical and dynamical properties of gold-based compounds (X3Au,X = Ti,Zr and V)

The structural, elastic, electronic and phonon properties of X₃Au (X?=?Ti, Zr and V) compounds in the A15 structure were obtained in the framework of the density functional theory (DFT) within the generalized gradient approximation (GGA). The equilibrium lattice constants, bulk modulus and elastic constants were calculated. The calculation of elastic constants revealed that V₃Au has the highest hardness nature and incompressibility along the x-axis among them. The computed elastic constants also provided information about the ductility of X₃Au compounds which were predicted using Pugh's criteria. The results indicated that all three compounds have ductile nature. The density of states calculations revealed that electrons of Ti, Zr and V provide most contribution to the conductivity of the compounds and thus cause a metallic bonding. The investigation of stability via phonon spectra of compounds showed that these compounds are dynamically stable in the A15 structure.     

Liberated color in leptoproduction

Within a spontaneously broken color gauge theory of integer charge quarks (icq) one expects standard “confined” QCD predictions for leptoproduction experiments (e.g.,μN→μX) to hold for energies below the threshold for color production; above such a threshold, however, the color degree of freedom must be excited leading to a threshold rise in structure functions. We predict the expected rises for μN and charged current (cc) νN and $\text{ν}\text{N}$ scattering within the “naive” parton model. Comparing these predictions with the available data on μN, cc νN and $\text{ν}\text{N}$ as well as e^?e⁺ experiments, we deduce that the lightest spin-parity 1^? color octet meson (like the gluon) as well as the lightest color octet (8, 8) baryon must lie above 7–8 GeV. This in turn closes the only window in the light mass region <3.1 GeV (i.e., the 1.1 to 1.8 GeVregion), whichhadsofarbeenleftopenasapossiblevalueforthephysicalmassofthegluon. Wenextobservethatthetrendofthemostrecent high-Q² high-W Michigan State-Fermilab experiment on μN scattering exhibiting a relatively sharp rise in F₂ above the expectations of confined QCD of order 15% at low x agrees very well with our predictions based on the gauge model of icq. This rise, if confirmed, would favor the hypothesis of gauge icq, and simultaneously imply a threshold for the liberated color octet (8, 8) state at nearly (9±0.6) GeV and a mass for the liberated gluon in the region 8 to 9.5 GeV. We remark that within a left-right symmetric gauge structure leading to icq, charged current scattering of laboratory neutrinos (νN→μ^?X) will excite color only provided that the charged gluons V⁺ mix with V-A gauge particles W_L⁺mrather then with the V+A gauge particles W_R⁺. Thus it is possible that the μN, e^?e⁺ and neutral current scattering of neutrinos (i.e., νN→νX) show signs of color excitation, while the charged current scattering of neutrinos does not. We discuss briefly the implications of the threshold for liberated color octet states possibly lying around 8–10 GeV or higher on future e^?e⁺ experiments as well as $\text{ν}\text{N}\text{,}\text{ν}\text{N}\text{,}\text{p}\text{p}\text{-}\text{and}\text{p}\text{p}\text{-}\text{produced}$ dilepton-search experiments.     

How quantitative is the concept of maximum overlap?

A criterion based on the concept of maximum overlap has been used as an optimizing principle to obtain approximate all valence electron wave functions for a variety of molecules. By means of this procedure, the wave functions are obtained without the use of parameters, semiempirical data, or integral approximations. Even though there are obvious errors in such an approach, the charge densities and dipole moments calculated from these wave functions have a surprising degree of validity. It does appear, though, that the results will be most reasonable for strongly covalent molecules, where large amounts of charge migration are not involved.

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Zusammenfassung Ein Kriterium auf Grund der Konzeption der maximalen Überlappung wurde als Optimalisierungsprinzip verwendet, um Wellenfunktionen für alle Valenzelektronen einer ganzen Reihe von Molekülen zu finden. Auf diesem Weg werden keine Parameter, semiempirische Daten oder Integral-näherungen benötigt. Trotz der offensichtlichen Vernachlässigungen sind die erhaltenen Ladungsdichten und Dipolmomente erstaunlich gut. Allerdings scheint es, als ob die Ergebnisse bei ausgeprägt kovalenten Molekülen am besten wären, wo größbere Ladungsverschiebungen nicht auftreten.

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Resumé Utilisation d'un critère fondé sur le concept du recouvrement maximum comme principe pour obtenir des fonctions d'onde pour tous les électrons de valence de toute une variété de molécules. A l'aide de ce procédé les fonctions d'onde sont obtenues sans l'emploi de paramètres, de données semi-empiriques ou d'approximation d'intégrales. Quoique cette approche comporte des erreurs évidentes, les densités de charge et les moments dipolaires calculés à partir de ces fonctions d'onde ont un degré de validité surprenant. Il apparaît néanmoins que les résultats seront d'autant plus raisonnables que les molécules seront plus covalentes et ne comporteront pas de transferts de charges importants.

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This work was supported in part by the National Science Foundation, Grant NSF-GP-16666.

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IBM Graduate Fellow.     

The regional distribution of copper and other trace elements in the human brain with special reference to Wilson's disease

The regional distribution of copper and other trace elements was determined in the brain of a patient deceased in Wilson's disease against a control brain. The heterogeneous distribution of copper was checked by scanning electron microscope equipped with an X-ray microanalyzer.     

Sleep disturbance effects of traffic noise—A laboratory study on after effects

Body movements during sleep and subjective sleep quality, as well as mood and performance were investigated after exposure to intermittent and continuous traffic noise during the night. In a first experiment, six young subjects slept in the laboratory for five nights; in a second experiment 12 subjects slept six consecutive nights in the laboratory. A good dose-response relationship was obtained between intermittent noise and subjective sleep quality: i.e., the higher the noise level, the poorer the sleep quality. A similar dose-response relationship was found for body movements immediately following noise peaks during nights with intermittent noise. Performance and mood tended to be worse after intermittent noise. However, these effects did not increase with an increase in noise levels. Compared with intermittent noise, continuous noise had a significantly smaller effect on sleep quality. Mood and performance were not worse after continuous noise. The results suggest that increased attention should be paid to peak noise levels when standards for nocturnal noise are set.     

Iron-57 Mössbauer Spectroscopic Studies of the High Temperature Properties of Metal-Doped Iron Oxides

⁵⁷Fe Mössbauer spectra recorded in situ in vacuo from chromium- and gallium-doped Fe₃O₄ at elevated temperatures show the dopant ions to depress the Curie temperature of Fe₃O₄ by ca. 70 K. Spectra recorded from aluminium-doped -Fe₂O₃ show the onset of conversion to aluminium-doped -Fe₂O₃ to begin at ca. 750 K, which is ca. 100 K above the conversion temperature for undoped -Fe₂O₃. The variation in magnetic hyperfine fields at temperatures exceeding ca. 750 K is similar to that recorded from -Fe₂O₃ when doped with zinc or magnesium. At temperatures exceeding 900 K the zinc doped -Fe₂O₃ partially converts to spinel-related ZnFe₂O₄.     

Error-Correcting Codes over an Alphabet of Four Elements

The problem of finding the values of A_q(n,d)—the maximum size of a code of length n and minimum distance d over an alphabet of q elements—is considered. Upper and lower bounds on A₄(n,d) are presented and some values of this function are settled. A table of best known bounds on A₄(n,d) is given for n 12. When q M < 2q, all parameters for which A_q(n,d) = M are determined.     

The role of 75H in fermion mass hierarchy

It is pointed out that the second generation fermions can have a natural mass relation m_μ = 3m_s at M_GUT if SU(5) symmetry breaking occurs through 75_H and 5_H. It is a first order supergravity effect and a small Yukawa coupling is not necessary.     

Neutronenaktivierungsanalyse von Verunreinigungen. Kobalt und Nickel in Uranverbindungen nuklearer Reinheit

Zusammenfassung Eine Methode zur Bestimmung von Nickel und Kobalt in Uranverbindungen nuklearer Reinheit wurde entwickelt. Die Hauptmasse des Urans wird vor der Bestrahlung papierchromatographisch entfernt. Kobalt und Nickel werden mit Hilfe der Isotope⁶⁰Co bzw.⁵⁸Co bestimmt. Zur Trennung der beiden Kobaltisotope wird die- Spektrometrie bzw. das Complement-subtraction-Verfahren angewendet.

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Summary A method has been developed for determining nickel and cobalt in uranium compounds of nuclear purity. The bulk of the uranium is removed by paper chromatography prior to the irradiation. Cobalt and nickel are determined with the aid of the isotopes⁶⁰Co and⁵⁸Ni respectively. Gamma spectrometry or the complement subtraction procedure is employed to separate the two cobalt isotopes.

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Résumé On a découvert une méthode de dosage du nickel et du cobalt dans les composés de l'uranium de pureté nucléaire. Avant l'irradiation, on sépare par Chromatographie sur papier la plus grande partie de l'uranium. On dose le cobalt et le nickel au moyen des isotopes Co⁶⁰ ou Ni⁵⁸. On utilise la spectrométrie gamma pour la séparation des deux isotopes du cobalt ou encore le procédé dit de «soustraction du complément».

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Vorgetragen beim Symposium für analytische Chemie in Graz, 29. September bis I. Oktober 1965.     

On the Classification of Self-Dual Codes over 𝔽5

 In this paper, we give the classification of self-dual 𝔽₅-codes of lengths 14 and 16. Up to equivalence, there are 53 and 535 such codes, respectively. It is also shown that there is no self-dual [18, 9, 8] code over 𝔽₅. Received: June 18, 2001 Final version received: April 9, 2002 RID="*" ID="*" Supported in part by the Academy of Finland under grants 44517 and 100500