Reaktionen bei dem thermochemischen ZnSe-Cyclus zur Darstellung von Wasserstoff

Ohne Zusammenfassung     

Search for anomalous multiphoton production at 100–300 GeV

We have carried out a search for anomalous multiphoton production in neutron-Ch₂ collisions at Fermilab. Both anomalous γ events as might be produced in the annihilation of a magnetic monopole pair, as well as events with smaller opening angles, such as those observed in cosmic ray emulsions by Schein et al. and others were sought. No evidence for either type of event was found. An upper limit ～2.7 μb is placed on the production cross section for “Schein” events or ～10^?2 that deduced from the cosmic ray data.     

An Analogue Equipment for Use in Production Planning

Many planning problems may be more efficiently resolved by an interaction of man and machine than by either alone. This paper considers an analogue equipment built to assist the production planning of a small number of products which share common labour and machine resources. It deals with up to four products and six production periods at a time. The stock levels which would result at the end of each period with a given forecast demand pattern and a given labour pattern are shown on an array of current meters. This rapid display of the stock position enables the operator to assess many more production plans in a given time than previous manual methods could allow. It also permits rapid modifications to be made to a plan with knowledge of the likely consequences. This is a simple and effective approach to a problem which is difficult to treat analytically.     

Interpolation by type I factors and the flip automorphism

Given two von Neumann algebras $\text{A}$ ?$\text{B}$ we study the relation between the existence of an interpolating type I factor $\text{F}$, namely $\text{A}$ ?$\text{F}$ ?$\text{B}$, the implementability of the flip automorphism of $\text{A}$ ? $\text{A}$ by a unitary in $\text{B}$ ? $\text{B}$, and the statistical independence of $\text{A}$ and $\text{B}$′ ($\text{A}$ and $\text{B}$′ generate a $\text{W}$¹-tensor product). As an application in Q.F.T. we derive in a natural way a structure theorem of Buchholz for the von Neumann algebras of local observables associated to free fields.     

Stable colloidal suspensions of nanostructured zirconium oxide synthesized by hydrothermal process

Nanocrystalline zirconium oxide was synthesized by hydrothermal treatment of ZrO(NO₃)₂ and ZrOCl₂ aqueous solutions at different temperatures and time in presence of hydrogen peroxide. Hydrothermal treatment of zirconium salts (0.25 and 0.50 mol L^?1) produced nanocrystalline monoclinic ZrO₂ powders with narrow size distribution, which were formed by the attachment of the smaller particles with crystallites size of 3.5 nm, estimated by means of the Scherrer’s equation and confirmed by transmission electronic microscopy. Typical monoclinic zirconium oxide X-ray powder diffraction patterns and Raman spectra were obtained for all the crystalline powders. It was observed that the crystallization depends strongly on the temperature, resulting in amorphous material when the synthesis was realized at 100 °C, and crystalline with monoclinic phase when synthesized at 110 °C, independently of the salt used. Zirconium oxide colloidal nanoparticles were formed only at hydrothermal treatments longer than 24 h. The stability of the colloids was successfully characterized of zeta potential, showing an initial value of + 59.2 mV in acid media and isoelectric point at pH = 5.2, in good agreement with previous studies.     

Adatom self-organization induced by quantum confinement of surface electrons

We present a novel mechanism of nanostructure growth based on quantum confinement of surface-state electrons. Ab initio calculations and the kinetic Monte Carlo simulations reveal the phenomenon of confinement-induced adatom self-organization in quantum corrals. Our studies indicate that new atomic-scale nanostructures can be engineered exploiting the quantum confinement of surface electrons.     

Metal-support interaction and redox behavior of Pt(1 wt %)/Ce0.6Zr0.4O2

The catalyst Pt(1 wt %)/Ce(0.6)Zr(0.4)O(2) is studied by CO-temperature programmed reduction (CO-TPR), isothermal oxygen storage complete capacity (OSCC), X-ray absorption spectroscopy (XAS) at the Pt L(III) edge, and in situ X-ray diffraction (in situ XRD), with the aim of elucidating the role of supported metal in CO oxidation by ceria-based three-way catalysts (TWC). The redox behavior of Pt(1 wt %)/Ce(0.6)Zr(0.4)O(2) is compared to that of bare ceria-zirconia. OSCC of redox-aged Pt/ceria-zirconia is twice that of bare ceria-zirconia, and the maximum of CO consumption occurs at a temperature about 300 K lower than redox-aged ceria-zirconia. XAS analysis allows one to evidence the formation of a platinum-cerium alloy in redox-aged samples and the stability of the metal particles toward oxidation and sintering during high-temperature treatments. Under CO flux at 773 K, bare ceria-zirconia shows a continuous drift of diffraction peaks toward smaller Bragg angles, due to a progressive increase of Ce(III) content. Under the same treatment, the structural rearrangement of Pt-supported ceria-zirconia starts after an induction time and takes place with an abrupt change of the lattice constant. The experimental evidence points to the role of supported Pt in modifying the redox properties of ceria-zirconia with respect to the bare support. It is proposed that the much faster bulk reduction observed by in situ XRD for redox-aged Pt/ceria-zirconia can be attributed to an easier release of reacted CO(2), producing a more effective turnover of reactants at the catalyst surface.     

New insights from X-ray photoelectron spectroscopy into the chemistry of covalent enzyme immobilization, with glutamate dehydrogenase (GDH) on silicon dioxide as an example

A three-step process for immobilization of glutamate dehydrogenase (GDH) on the surface of silicon dioxide has been studied by X-ray photoelectron spectroscopy (XPS). The enzyme layer was deposited on the silicon dioxide surface after first exposing the surface to 3-aminopropyltriethoxysilane (3-APTS) and reacting the silylated surface with glutaraldehyde (GA). Fine XPS analysis, performed after each step of the chemical procedure, revealed unknown details of the step-by-step construction of the enzyme layer under different experimental conditions.     

Δ h -Appell sequences and related interpolation problem

A determinantal form for Δ _h -Appell sequences is proposed and general properties are obtained by using elementary linear algebra tools. As particular cases of Δ _h -Appell sequences the sequence of Bernoulli polynomials of second kind and the one of Boole polynomials are considered. A general linear interpolation problem, which generalizes the classical interpolation problem on equidistant points, is proposed. The solution of this problem is expressed by a basis of Δ _h -Appell polynomials. Numerical examples which justify theoretical results on the interpolation problem are given.