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.     

Nonpharmacological interventions for insomnia in older adults: A meta-analysis of treatment efficacy.

The benefit of nonpharmacological interventions for insomnia in old age was investigated. A total of 13 single-outcome studies from 1966–1998 involving 388 patients (mean age exceeding 60 years, minimum age in sample, 50 years) were included in a meta-analysis of treatment efficacy. This analysis demonstrated that behavioral interventions produce improvements in sleep parameters of older insomniacs, measured in terms of sleep-onset latency, number of nocturnal awakenings, time awake after sleep onset, and total sleep time. Clinical improvements seen at posttreatment were maintained at followups (averaging 6 months). It is concluded that behavioral treatments produce significant and long-lasting improvements in the sleep pattern of older insomniacs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Einfluß von Anlaßbehandlungen auf die Versetzungsanordnung (Substruktur) und Rekristallisation in hochreinem Eisen

Anlassen von hochreinem Eisen mit einer Querschnittsabnahme zwischen 18 und 80% bei Raumtemperatur und - 196°C gewalzt. Untersuchung der Substruktur mit elektronenmikroskopischen Durchstrahlungsaufnahmen. Erörterung der Keimbildungsvorgänge. Aufnahme einer isochronen Anlaßkurve und Ermittlung der Rekristallisationstemperatur. Vergleich von technisch reinem und hochreinem Eisen nach Anlaßbehandlungen hinsichtlich der Substruktur und des Keimbildungsverhaltens.