Physical properties and electrochemical performance of molybdenum–lead-germanate glasses and glass ceramics

Glasses and glass ceramics of the xMoO₃(100?x)[7GeO₂·3PbO] system where x=0–30 mol% MoO₃ were synthesized and characterized in order to obtain information about the structural correlations and the relationship between structure and physical properties in these materials. Changes of the FTIR, UV–vis and EPR data are discussed in view of the glass network structural changes determined by the evolution of molybdenum ions state, glass composition and MoO₃ concentration.The spectroscopic studies indicate that with increasing of MoO₃ content a fraction of the Mo⁶⁺ ions convert Mo³⁺ and Mo⁵⁺ ions. Accordingly, these modifications cause the depolymerization of the host network, the increase of the structural disorder and formation of GeO₂ and PbMoO₄ crystalline phases. The shape of EPR spectra is modified by the increase of the MoO₃ concentration indicating that molybdenum ions exists in glass and glass ceramics in more than one valence state. The EPR spectra contain a broad line located at g～5.2 and, for the samples with a MoO₃ content up to x≥15 mol%, the presence of the hyperfine structure characteristic for the Mo⁵⁺ ions can be observed, too.The electrochemical performances of the glass and glass ceramics samples with x=10 and 30 mol% MoO₃ were demonstrated by cyclic voltammetry.     

Entwicklung und Erprobung eines Wäschersystems zur CO2‐Abreinigung aus Rauchgasen mithilfe alkalischer Reststoffe

An innovative, technical approach for the reduction of CO₂ emissions is presented that utilizes alkaline wastes to capture CO₂ from flue gases in stable mineral form. Comprehensive pilot‐scale experiments were conducted with the developed flue gas scrubbing system at a power plant site. By optimizing the process parameters gas flux, CO₂ partial pressure, circulation flux and suspension liquid‐to‐solid ratio, a CO₂ binding of 40 – 90 g kg^–1 waste could be reached and up to 25 % of the CO₂ could be captured. The new technique is economically advantageous especially when both alkaline waste and CO₂ are produced on site and when the carbonated products can be used as secondary resources.     

Der Enzyklopädist der Technischen Mechanik des 19. Jahrhunderts – Zum 200. Geburtstag von Julius Weisbach (1806–1871)

Encyclopaedist of 19th century applied mechanics – Commemorating Julius Weisbach's 200th birthday. With his two‐volume “Lehrbuch der Ingenieur‐ und Maschinen‐Mechanik” (Textbook of engineering and machine mechanics) (1845–1887), his handbook “Der Ingenieur” (The Engineer) und the journal “Der Civilingenieur” (The Civil Engineer), Julius Weisbach (1806–1871) created an image of applied mechanics reflecting the state of the industrial revolution in Germany in content and form. For the first time, he subjected the whole ‘artefact world’ of the contemporary engineer to a simple and comprehensible analysis based on applied mechanics. With his encyclopaedic publication system Weisbach succeeded in providing a valid representation of the historical/logical middle of the discipline formation period of applied mechanics (1825–1900).     

Hydraulischer Grundbruch und Versagen des Erdwiderlagers von Baugrubenwänden

Failure by heave and failure of the earth support of excavation walls. The present article deals with the phenomenon of heave at the earth support of excavation walls. It is restricted to a homogeneous subsoil in the area of the bottom of the excavation. Starting with some questions, which result from the required verifications of limit states, two mechanical models are described, which differ on the stability of the skeleton of grains. The possible failure mechanisms for hydraulically stressed earth supports of excavation walls are discussed. With two exemplary deep excavations, one of it wide, the other narrow, the respective verifications of limit states in the classical form as well as on basis of Finite Element calculations are carried out. Finally the results are discussed and some conclusions are drawn from it. Also requirements for verifications of limit states on basis of FEM calculations are formulated.