Über die Verwendung des Energiesatzes zur Lösung von Oberflächenwellenproblemen

Zusammenfassung Es wird gezeigt, daß im Falle der Wellenerrcgung durch stationär schwingende Erreger der Energiesatz auf rechnerisch einfachem Wege eine Näherungsbeziehung für die Amplitude der ins Unendliche abwandernden Oberflächenwellen ergibt. Die Näherung erweist sich dabei um so besser, je kleiner die Längenabmessungen des Wellenerregers gegenüber den sonst vorkommenden Längen (Eintauchtiefe, Wellenlänge) sind. Diese allgemein abgeleitete Näherungsbeziehung wird für zwei einfache Fällc der Wellenerregung durchgerechnet. Der erste Fall, die periodische Quelle führt auf ein einfaches Ergebnis, das in Übereinstimmung mit der für diesen Fall der Wellenerregung bereits vorhandenen strengen Theorie ist¹. Der zweite Fall, der Tauchschwingungen ausführende Quader führt ebenfalls auf eine einfache Beziehung für die erzeugte Wellenamplitude. Für den Grenzfall verschwindender Quaderbreite geht diese wieder in die Lösung für die periodische Quelle über. Für den Grenzfall verschwindender Eintauchtiefe wird der Vergleich mit einer schon vorhandenen Theorie durchgeführt. Endlich werden die beiden gerechneten Fälle mit am Tauchschwingungen ausführenden Quader durchgeführten Experimenten verglichen.Die vorstehende Arbeit wurde auf Veranlassung von Herrn ProfessorSchuler im Institut für angewandte Mechanik der Universität Göttingen durchgeführt. Herrn Prof.Schuler sowie Herrn Prof.Prandtl bin ich für die Förderung der Arbeit zu Dank verpflichtet.     

Size‐Selective Encapsulation of Hydrophobic Guests by Self‐Assembled M4L6 Cobalt and Nickel Cages

Subtle differences in metal–ligand bond lengths between a series of [M₄L₆]^4? tetrahedral cages, where M=Fe^II, Co^II, or Ni^II, were observed to result in substantial differences in affinity for hydrophobic guests in water. Changing the metal ion from iron(II) to cobalt(II) or nickel(II) increases the size of the interior cavity of the cage and allows encapsulation of larger guest molecules. NMR spectroscopy was used to study the recognition properties of the iron(II) and cobalt(II) cages towards small hydrophobic guests in water, and single‐crystal X‐ray diffraction was used to study the solid‐state complexes of the iron(II) and nickel(II) cages.     

Intermediate coupling model description of55Fe and57Fe

The properties of the negative parity states of⁵⁵Fe and⁵⁷Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states.     

Donor-acceptor complex chromatography (DACC) Part I. Introduction and nomenclatur

Summary Liquid chromatographic separations by the formation of donor-acceptor complexes (DAC) are reviewed. The article treats these examples, where donor or acceptor compounds are coated on, or chemically bonded to, a matrix. The effect of chemical structure of donors and acceptors, the effect of temperature and solvent composition of the mobile phase on retention is discussed.     

Higher-order effects in hopping-type transport of small polarons. II. Quantal occurrence-probability treatment

In the present paper, the higher-order corrections to the standard expression for the hopping rate of small polarons, obtained in the preceding paper, are here derived within the framework of the recently developed quantal occurrence-probability formulation of hopping-type transport. It is shown that the relative importance of the higher-order corrections is considerably enhanced when the vibrational spectrum of the host crystal is characterized by weak dispersion. The role of ultraweak dispersion for both two-site and multisite “correlated” hopping is discussed.     

Strong bounds on weak couplings

Analysis of nonleptonic ΔS = 1 weak decays strongly restricts the possible size of right-handed weak couplings. Limits thus obtained are competitive with those obtained via other means.     

Multiple ionization of argon in coincidence with projectile ions in 60–120 MeV Si q+-Ar collisions

A projectile ion-recoil ion coincidence technique has been employed to study the multiple ionization and the charge transfer processes in collisions of 60–120 MeV Si ^q+ (q = 4−14) ions with neutral argon atoms. The relative contribution of different ionization channels, namely; direct ionization, electron capture and electron loss leading to the production of slow moving multiply charged argon recoil ions have been investigated. The data reported on the present collision system result from a direct measurement in the considered impact energy for the first time. The total ionization cross-sections for the recoil ions are shown to scale as q ^1.7/E _p ^0.5 , where E _p is the energy in MeV of the projectile and q its charge state. The recoil fractions for the cases of total- and direct ionizations are found to decrease with increasing recoil charge state j. The total ionization fractions of the recoils are seen to depend on q and to show the presence of a ‘shell-effect’ of the target. Further, the fractions are found to vary as 1/j ² upto j = 8+. The average recoil charge state 〈j〉 increases slowly with q and with the number of lost or captured electrons from or into the projectile respectively. The projectile charge changing cross-sections σ _qq′ are found to decrease with increasing q for loss ionization and to increase with q for direct-and capture ionization processes respectively. The physics behind various scaling rules that are found to follow our data for different ionization processes is reviewed and discussed.     

Overview of hadronic parity violation

The subject of hadronic parity violation is nearly fifty years old, but a good deal of uncertainty remains, despite many efforts both theoretical and experimental. A brief summary of the field is presented and a plan is proposed for new experimental work which, when combined with a new theoretical tack based on effective field theory, should lead to resolution of the present difficulties.