Analyse heterogener Legierungen durch Isolierung und durch Lokalanalyse mit der Elektronenstrahl-Mikrosonde

Zusammenfassung Die beiden wichtigsten Verfahren zur quantitativen Analyse der Gefügebestandteile heterogener Legierungen sind die potentiostatische Isolierung und die Lokalanalyse mit der Elektronenstrahlmikrosonde. Manganstähle mit Carbiden definierter Zusammensetzung und Größe boten die Möglichkeit, erstmalig die quantitativen Aussagen dieser beiden Methoden miteinander zu vergleichen.Dabei erbrachte die Isolierung durch die gleichzeitige analytische Erfassung größerer Mengen der Matrix und der Carbidphasen sehr genaue Angaben ihrer durchschnittlichen Zusammensetzung. Örtliche Konzentrationsänderungen in derselben Phase werden jedoch nicht erfaßt. Dagegen zeigte sich, daß die lokale Röntgenspektralanalyse zwar vergleichbare Ergebnisse lieferte, aber auch bei Anregung mit einem feinfokussierten Elektronenstrahl (Durchmesser <1) die Genauigkeit der Werte bei Teilchengrößen <5 durch Anregung von Nachbarbereichen merkbar beeinflußt wird.Zerlegung und Phasenanalyse einerseits sowie Lokalanalyse mit der Elektronenstrahlmikrosonde anderseits haben ihren eigenständigen Anwendungsbereich. Unter Berücksichtigung der gegebenen Grenzen können sich beide Methoden zur Analyse metallischer Werkstoffe sinnvoll ergänzen.

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Summary The two most important procedures for the quantitative analysis of the structural constituents of heterogeneous alloys are the potentiostatic isolation and the local analysis by means of the electron beam microsonde. Manganese steels with carbides of definite composition and magnitude offered the possibility for securing quantitative statements for the first time with respect to the comparative merits of these two methods.The isolation gave very precise information concerning the average composition through the concurrent analytical involvement of larger amounts of the matrix and the carbide phases. However, local alterations in the concentration within the same phase were not revealed. On the other hand, it was found that though the local X-ray spectral analysis yielded comparable results, the accuracy of the values at particle sizes <5 is markedly influenced through excitation of neighboring regions when the excitation was due to a fine-focused electron beam (Ø <1).Decomposition and phase analysis on one hand and local analysis with the electron beam-microsonde on the other have their individual fields of application. If the given limitations are taken into account, both methods may contribute judiciously to the analysis of metallic industrial materials.

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Résumé L'isolement potentiostatique et l'analyse locale par la microsonde électronique représentent les deux procédés les plus importants pour l'analyse quantitative des constituants entrant dans la texture des alliages hétérogènes. Les aciers au manganèse avec carbures en composition et quantité définies offrent la possibilité, pour la première fois, de comparer entre elles les indications quantitatives de ces deux méthodes.L'isolement par détermination analytique simultanée de plus grandes quantités de matrice et de la phase carbure a rendu des données très précises de leur composition moyenne. Les modifications de concentration locale dans la même phase n'ont pourtant pas été atteintes. Par contre, il s'est avéré que l'analyse spectrale locale par rayons X conduisait à des résultats comparables, mais en excitant par un faisceau d'électrons finement focalisé (Ø<1), l'exactitude de la valeur pour les particules de dimensions inférieures à 5 se trouve influencée de façon notable par excitation des régions voisines.La séparation et l'analyse des phases d'une part, l'analyse locale par la microsonde à faisceau d'électrons d'autre part, ont leur domaine d'application propre. En tenant compte des limites données, les deux méthodes peuvent se compléter d'une manière judicieuse pour l'analyse des produits métalliques oeuvrés.

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Vortrag anläßlich des Kolloquiums für metallkundliche Analyse mit besonderer Berücksichtigung der Elektronenstrahl-Mikroanalyse, Wien, 22. Oktober 1964.     

Synthèse partielle et propriétés oncostatiques des pseudo-tubulosines,analogues de l'émétine et de la tubulosine

Partial Synthesis and Oncostatic Properties of Pseudotubulosines, Analogues of Emetine and Tubulosine Pseudotubulosines, structural analogues of emetine and tubulosine, have been synthesized by either Pictet-Spengler or Bischler-Napieralski condensation from dihydrocorynantheal or corynantheidal. Spectral data, cytotoxic and oncostatic properties of these new alkaloids are described.     

Emissionsspektrometrische Analyse von Roheisen

Zusammenfassung Die spektrometrische Analyse von weiß erstarrtem Roheisen (auf C, Si, Mn, P, S, Cu) ist mit der gleichen Anregung und in der gleichen Funkzeit wie diejenige von Stahl möglich. Eine spezielle Kalibriertechnik mit Stahlproben garantiert ein ausreichend reproduzierbares und richtiges Resultat in relativ kurzer Zeit (20 sec).

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Emission-spectrometrical analysis of pig iron

The conditions of pig iron analysis by using a direct reading spectrometer for routine determination of C, Si, Mn, P, S and Cu, the influence of sampling and a new calibration technique of the instrument are described. The whole time needed for complete spectrometrical analysis is about 20 sec.

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Wir sind Herrn T. Nientiedt für zahlreiche Anregungen und Diskussionen zu Dank verpflichtet.     

Partial cross sections and density-of-states effects in the valence-band photoemission from solid nitrogen

Photoelectron energy distribution curves from solid nitrogen were measured for excitation energies to 40 cV using synchrotron radiation. Partial cross sections for emission from 3σ_g, 1π_u and 2σ_u derived valence bands show pronounced mauna 3, 4, 2.9 and 3.0 eV above the vacuum levels, interpreted as due to high density of conduction-band final states. These states are related to π*_g negative-ion shape resonances.     

Fluorescence quenching of alternant and non-alternant polycyclic hydrocarbons by electron transfer

Rate constants of fluorescence quenching by electron acceptors are greater for alternant than for non-alternant hydrocarbons with equal E_oo. The reverse is true for quenching by electron donors. This is consistent with the lowering of the π-orbital energies of non-alternant compared to alternant polycyclic hydrocarbons of equal E_oo.     

Configuration and E/Z interconversion mechanism of O(S)-allyl-S(O)-methyl-N-(acridin-9-yl) iminothiocarbonate

The configuration and dynamic behavior of O-allyl-S-methyl-N-(acridin-9-yl)iminothiocarbonate (1) and its S-allyl-O-methyl regioisomer (2) were studied using quantum chemical calculations and by applying a novel graphical method to scatter maps obtained from MD simulations for evaluation of an NOE-weighted internuclear distance (r(NOE)). Energy calculations indicated that the Z configuration was predominant for each compound and, further, this was supported both by the calculated chemical shifts and the r(NOE). Both N-inversion- and rotation-type transition-state structures were also calculated for the E/Z isomerization process, the results indicating that the preferred interconversion mechanism for 1 is N-inversion, but contrastingly, interconversion via rotation is equally as probable as N-inversion for 2. This supports the notion that one or the other or both pathways can be active and each system needs to be assessed on a case-by-case basis.     

Electron impact and single photon ionization cross sections of neutral silver clusters

Neutral silver atoms and small clusters Ag _n (n=1...4) were generated by sputtering, i.e. by bombarding a polycrystalline silver surface with Ar⁺ ions of 5 keV. The sputtered particles were ionized by a crossed electron beam and subsequently detected by a quadrupole mass spectrometer. In alternative to the electron impact ionization, the same neutral species were also ionized by single photon absorption from a pulsed VUV laser (photon energy 7.9 eV), and the photoionization cross sections were evaluated from the laser intensity dependence of the measured signals. By in situ combining both ionization mechanisms, absolute values of the ratio σ _e (Ag _n )/σ _e (Ag) between the electron impact ionization cross sections of silver clusters and atoms could be determined for a fixed electron energy of 46 eV. These values can then be used to calibrate previously measured relative ionization functions. By calibrating the results using literature data measured for silver atoms, we present absolute cross sections for electron impact ionization of neutral Ag₂, Ag₃ and Ag₄ as a function of the electron energy between threshold and 125 eV.     

Synthesis and cytotoxic activity of 11-nitro and 11-amino derivatives of acronycine and 6-demethoxyacronycine

Condensation of 2-chloro-3-nitrobenzoic acid with either 5-amino-7-methoxy-2,2-dimethyl-2H-chromene or 5-amino-2,2-dimethyl-2H-chromene afforded diphenylamines 14 and 15. Trifluoroacetic anhydride mediated cyclization gave the corresponding acridones 16 and 17, which were subsequently N-methylated and reduced to 11-aminoacronycine and 11-amino-6-demethoxyacronycine. These two amino compounds, which gave stable water soluble salts, were 2- to 3-fold more potent than acronycine or 6-demethoxyacronycine in inhibiting L1210 cell proliferation.     

Electronic influences on 3J(C,H) coupling constants via -S-, -S(O)- and -SO2-: their determination, calculation and comparison of detection methods

3J(C,H) coupling constants via a sulfur atom in two series of compounds, both including a sulfide, a sulfoxide and a sulfone, were detected experimentally and calculated by quantum mechanical methods. In the first series (1-3) the coupling between a hydrogen, bonded to an sp3 carbon, and an sp2 carbon is treated; the second series (4-6) deals with the coupling between a hydrogen, bonded to an sp3 carbon, and an sp3 carbon. Different pulse sequences (broadband HMBC, SelJres, 1D HSQMBC, J-HMBC-2, selective J-resolved long-range experiment and IMPEACH-MBC) proved to be useful in determining the long-range 3J(C,H) coupling constants. However, the dynamic behaviour of two of the compounds (4 and 6) led to weighted averages of the two coupling constants expected (concerning equatorial and axial positions of the corresponding hydrogens). DFT calculations proved to be useful to calculate not only the 3J(C,H) coupling constants but also the different contributions of FC, PSO, DSO and SD terms; the calculation of the Fermi contact term (FC) was found to be sufficient for the correct estimation of 3J(C,H) coupling constants.     

Striktionseigenschaften von Regelscharen imE n

Let ={e(u)|uI} be a one-parameter family of straight lines forming a ruledC ^r-2-surface E ⁿ (n2,r1) without singular generatorse(u) (uI). As a synopsis, a generalization and an improvement of various results already known about the strictional properties of ruled surfaces E ⁿ (especially in the casen=3) the author demonstrates a uniform geometrical way of defining and uniquely obtaining thestriction point S(u) and theparameter of distribution d(u) of a generatore(u) under the minimal assumptions thate(u)E ⁿ (n2) be noncylindrical andr1. Other methods of obtainingS(u) andd(u) are discussed in comparison, and special strictional properties ofskew ruled surfaces E ⁿ are proved.

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Herrn Prof. Dr. H. R. Müller zum 65. Geburtstag