Bridging the gap between homogeneous and heterogeneous catalysis: ortho/para H(2) conversion, hydrogen isotope scrambling, and hydrogenation of olefins by Ir(CO)Cl(PPh(3))(2)

Some transition metal complexes are known to catalyze ortho/para hydrogen conversion, hydrogen isotope scrambling, and hydrogenation reactions in liquid solution. Using the example of Vaska's complex, we present here evidence by NMR that the solvent is not necessary for these reactions to occur. Thus, solid frozen solutions or polycrystalline powdered samples of homogeneous catalysts may become heterogeneous catalysts. Comparative liquid- and solid-state studies provide novel insight into the reaction mechanisms.     

Über die in einem einfachen Verlustsystem induzierten stochastischen Prozesse

Zusammenfassung Zweck dieser Untersuchungen ist es, für einGI|G|1) — Servicesystem ohne Warteplätze die Prozesse der von diesem System abgewiesenen Kunden bzw. nach erfolgtem Service ausgeschiedenen Kunden im Hinblick auf ihre Verwendung als Eingangsprozesse für weitere Servicesysteme zu charakterisieren.Für beide Prozesse ist es gelungen, die Anzahl der in einem beliebigen Zeitintervall abgewiesenen bzw. ausgeschiedenen Kunden durch Wahrscheinlichkeitsgesetze zu beschreiben. Darüber hinaus konnten notwendige und hinreichende Bedingungen angegeben werden, wann der Prozeß der ausgeschiedenen Kunden wieder die EigenschaftGI besitzt.

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Summary The purpose of this investigation is, to describe in case of aGI |G|1) — servicesystem without waiting-room the processes of clients refused by this system respectively cast out after having finished service with regard to their applying as input-processes of any other servicesystem.It has been achieved for both processes to set up the probability laws of the number of clients refused respectively cast out during any interval of time.Beyond these results the author has quoted necessary and sufficient conditions for the process of clients cast out to possess the propertyGI.

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Diese Untersuchung wurde im Rahmen eines von Herrn Prof. Dr.H. Söhngen geleiteten Forschungsauftrags des BMVtdg durchgeführt.

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Vorgel. v.:H. Söhngen.     

Oligofunctional amphiphiles featuring geometric core group preorganization: synthesis and study of Langmuir and Langmuir-Blodgett films

Based on the principle of supramolecular preorganization, a new type of oligofunctional amphiphile, of which compounds 1-4 are representative structures, has been designed and synthesized. The typical feature of their structure is a highly rigid and geometrically well-defined central unit composed of ethynylene substituted aromatic spacers with different numbers of amphiphilic segment groups (also of a rigid geometric design) attached to it. The molecules form well-defined Langmuir films when spread from a solution at the air/water interface or when a 10(-4) M aqueous CaCl2 solution was used as the subphase. By analysis of the surface pressure-surface area (pi-A) isotherms, information on the packing behavior and orientation of the amphiphilic molecules depending on the molecular structure could be obtained. Morphological characterization of the dynamic process of monolayer compression at the air/water interface was carried out by Brewster angle microscopy, illustrating several phase states visualized as snap shots. Thin monolayer films produced on a 10(-4) M aqueous CaCl2 subphase can be transferred to a mica solid support by the Langmuir-Blodgett technique. Tapping mode atomic force microscopy reveals a surface topography of the monofilms composed of 1 and 3 that differ in roughness and also in the properties of elasticity, hardness and adhesive strength. X-Ray crystal structure analysis of three relevant intermediate compounds of the synthesis were successfully determined giving an indication of the potential structural features inherent in the new amphiphiles.     

Enhancement of a 24.77-nm line emitted by the plasma of a boron nitride capillary discharge irradiated by a high-intensity ultrashort laser pulse

Investigations of plasma produced by a boron nitride capillary discharge irradiated with a guided 20-TW Ti: sapphire laser pulse at a peak intensity of 4 x 10(18) W/cm2 are presented. The guided laser radiation in the plasma channel generated He-like ions that, subject to suitable plasma temperature, recombined into Li-like nitrogen ions. Intense radiation at a wavelength of 24.77 nm was observed, indicating possible lasing at the 3d(5/2) - 2p(3/2) transition in Li-like nitrogen.     

Universal fundamental systems in ordered Banach spaces

Let E be a separable Banach space ordered by a reproducing cone with empty interior. We prove the existence of operator functions A : [0, ) P (P the cone of monotone increasing linear operators) and of initial values x₀ such that the solution of x (t) = A(t) x(t), x(0) = x₀, is dense in E.Received: 27 February 2004