Phasengleichgewichte des Schnittes FeOn–CaO im Dreistoffsystem FeO–Fe2O3–CaO bei Eisensättigung

Überprüfung der Schmelzgleichgewichte des Dreistoffsystems FeO–Fe₂O₃–CaO auf der wüstitreichen, eisengesättigten Seite des Systems. Angaben über die Ergebnisse der thermischen Analysen, isothermen Halteversuche und mikroskopischen Untersuchungen. Aussagen über den quasibinären Schnitt Eisen-Kalkferrit bei Temperaturen unter 1150 °C sowie über den quasibinären Schnitt Calciowüstit-Kalk über 1150 °C.     

A relation between space,return and dual return complexities

We introduce the dual return complexity and prove that the return complexity classes and the dual return complexity classes of nondeterministic Turing machines coincide with the tape complexity classes of Turing machines with auxiliary pushdown tape for resource functions ??id, id being the identity function.     

Eine verbesserte Methode zur Bestimmung der maximalen Emulgierkapazit?t von Proteinl?sungen

Zusammenfassung Am Beispiel der Milchproteine wird die Methode zur Bestimmung der maximalen Emulgierkapazität optimiert. Die Methode beruht darauf, daß am Inversionspunkt einer Emulsion der elektrische Widerstand sprunghaft ansteigt. Experimentell überprüft wurden die Parameter Proteinkonzentration, pH-Wert, Öl-Dosierungsrate, Ultra-Turrax-Drehzahl und Versuchsdauer. Ferner wurden Forderungen an die Ermittlungdes Leerwertes begründet. Durch Festlegen der stofflich und methodisch bedingten Einflußgrößen gelingt es, den Variationskoeffizienten auf Werte um 2,0% zu minimieren. Die vorgestellte Methode ist mit gutem Erfolg auf alle löslichen Proteine übertragbar und erfüllt die Anforderungen einer Standardisierung.

---

An improved method for determining the maximum value of emulsifying capacity of protein solutions

Summary A method for the examination of the maximum value of emulsifying capacity was optimized using milk proteins. This method is based on a sudden increase in the electrical resistance at the inversion point of the emulsion. The following parameters were tested: protein concentration, pH value, rate of oil dosage, speed of the Ultra-Turrax, time needed for one experiment, and the requirements for preparing the blank. By fixing these parameters it is possible to minimize the coefficient of variation of about 2.0%. This method is successfully applicable for all soluble proteins and meets all the requirements for standardisation.

     

An analysis of the ammonium chloride route to anhydrous rare-earth metal chlorides

The ammonium chloride route to anhydrous rare-earth metal trichlorides, RECl₃, is a two-step procedure consisting in, firstly, the (dry or wet) synthesis of a complex chloride, (NH₄)₃ RECl₆ (t≈ 220°C) and, secondly, its decomposition either directly (small RE, t≈ 425°C) or via the intermediates (NH₄)₂ RECl₅ (large RE, t≈ 385°C) and NH₄RE₂Cl₇ (medium-size RE), respectively.     

Stability of superconducting states out of thermal equilibrium

Quasiparticles of superconductors can be manipulated either by irradiation or tunnel injection such that substantial changes of the gap (order parameter) occur which are most pronounced close to the transition temperature. These phenomena are investigated by a theory which is based on the combined system of the Boltzmann equation and the BCS gap equation. Several stationary, spatially homogeneous states are found in some range of temperatures. A linear stability analysis reveals two types of behavior, depending, essentially, on whether quasiparticle diffusion increases or decreases the stability. In a representative situation of the first type, two states turn out to be locally stable. An investigation of a nonlinear equation of motion for the order parameter leads to the conclusion that a first-order phase transition between these two states occurs at a given temperature. In a situation of the second type, one finds that fluctuations of a definite wave vector destroy the spatially homogeneous state and lead to a stable state of layered structure.     

Computing simple bifurcation points using a minimally extended system of nonlinear equations

The present paper deals with the computation of simple bifurcation points of nonlinear parameter dependent equations. At first, a minimally extended system of nonlinear equations is constructed by addition of one parameter and two equations. This augmented system has an isolated solution which yields to the simple bifurcation point directly. Using the structural properties of this auxiliary system an adapted Newton-like method is developed not requiring evaluations of second derivatives. Finally, the results of some computer experiments show the efficiency of theR-quadratically convergent method.     

Synthesis and crystal structure of the inter-alkali metal iodide Cs2Li3I5

Cs₂Li₃I₅ was obtained from the reaction of CsI, Li and I₂ in a sealed tantalum tube and colorless single crystals grown from the melt by slow cooling. This first inter-alkali metal iodide crystallizes in the monoclinic crystal system (C2/m, Z= 2) with a= 1666.8(6), b= 472.1(1), c= 1098.7(4) pm, β= 115.73(3)°. As the result of a x-ray crystallographic structure determination (R= 0.069, R_W= 0.066), Li⁺ is surrounded tetrahedrally (two thirds) and octahedrally (one third) by iodide. Cornersharing double chains of [LiI₄] tetrahedra are connected with edge-sharing chains of [LiI₆] octahedra to a layer of the composition [Li₃I₅]. Bicapped trigonal prisms [CsI₃] share faces and edges so that a network of the composition [Cs₂I₅] is formed which contains the necessary tetrahedral and octahedral holes for Li⁺.     

Einsatz von mathematischer Simulation und Miniplant-Technik in der Verfahrensentwicklung

Use of mathematical simulation and miniplant techniques in process development . An integrated study of synthesis and workup or of entire processes is often required in the development of chemical processes. This leads to a large number of possible solutions, of which the most economic one must be selected. This variety can only be mastered at reasonable expense with the aid of present-day techniques. Examples are presented to show how just a few economic possibilities can be selected and optimized from the plethora of alternatives in simulation calculations based on just a few properties of the materials involved. Economics is the basis of all evaluation. Use of miniplants is considered in the second part of the article, and costs and time-expenditure are compared with those for industrial pilot plants. Planning and evaluation of experiments raise the effectiveness of this empirical work. Problems of scale-up are considered, and the advantages of physico-chemically sound scale-up models are demonstrated.