REAPOR® - a new glass foam as sintered material

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Crystallization Kinetics of LaF3 Nanocrystals in an Oxyfluoride Glass

Nanocrystallization of LaF3 in a glass of composition 55SiO2– 20Al2O3–15Na2O–10LaF3 (mol%) has been achieved by heat treatment above the glass transition temperature. A maximum crystal size of 14 nm has been attained, with the crystalline fraction and crystal size dependent on the time and temperature of thermal treatment. The effect of lanthanum fluoride crystallization is noticeable from the microstructural and compositional changes in the glass matrix, which have been studied using several techniques, including viscosity, dilatometry, X-ray diffraction, and quantitative Rietveld refinement, transmission electron microscopy, and differential scanning calorimetry. The crystallization mechanism is shown to occur via regions of La- and Si-phase separation in the glass, from which the fluoride crystals develop during heat treatment. The interface between the glass matrix and the crystals in the demixed ranges is enriched in network formers, mainly SiO2, creating a viscous barrier, which inhibits further crystal growth and limits the crystal size to the nanometric range.Peer reviewe

The Generation of Fullerenes

We describe an efficient new algorithm for the generation of fullerenes. Our implementation of this algorithm is more than 3.5 times faster than the previously fastest generator for fullerenes -- fullgen -- and the first program since fullgen to be useful for more than 100 vertices. We also note a programming error in fullgen that caused problems for 136 or more vertices. We tabulate the numbers of fullerenes and IPR fullerenes up to 400 vertices. We also check up to 316 vertices a conjecture of Barnette that cubic planar graphs with maximum face size 6 are hamiltonian and verify that the smallest counterexample to the spiral conjecture has 380 vertices.Comment: 21 pages; added a not

The oil-dispersion bath in anthroposophic medicine – an integrative review

<p>Abstract</p> <p>Background</p> <p>Anthroposophic medicine offers a variety of treatments, among others the oil-dispersion bath, developed in the 1930s by Werner Junge. Based on the phenomenon that oil and water do not mix and on recommendations of Rudolf Steiner, Junge developed a vortex mechanism which churns water and essential oils into a fine mist. The oil-covered droplets empty into a tub, where the patient immerses for 15–30 minutes. We review the current literature on oil-dispersion baths.</p> <p>Methods</p> <p>The following databases were searched: Medline, Pubmed, Embase, AMED and CAMbase. The search terms were 'oil-dispersion bath' and 'oil bath', and their translations in German and French. An Internet search was also performed using Google Scholar, adding the search terms 'study' and 'case report' to the search terms above. Finally, we asked several experts for gray literature not listed in the above-mentioned databases. We included only articles which met the criterion of a clinical study or case report, and excluded theoretical contributions.</p> <p>Results</p> <p>Among several articles found in books, journals and other publications, we identified 1 prospective clinical study, 3 experimental studies (enrolling healthy individuals), 5 case reports, and 3 field-reports. In almost all cases, the studies described beneficial effects – although the methodological quality of most studies was weak. Main indications were internal/metabolic diseases and psychiatric/neurological disorders.</p> <p>Conclusion</p> <p>Beyond the obvious beneficial effects of warm bathes on the subjective well-being, it remains to be clarified what the unique contribution of the distinct essential oils dispersed in the water can be. There is a lack of clinical studies exploring the efficacy of oil-dispersion baths. Such studies are recommended for the future.</p

Viscosity, Relaxation And Elastic Properties Of Photo-Thermo-Refractive Glass

Viscometry, ultrasonic echography and mechanical spectroscopy were applied to explore the thermo-mechanical properties of a photo-thermo-refractive (PTR) glass. Newtonian shear viscosity and ultrasonic velocity were used to determine the Maxwell time of structural relaxation. Two fast relaxation modes are found in PTR glass below glass transition temperature, which are attributed to alkali and mixed cation mobility. Respective activation energies, Eγ = 72 ± 4 kJ mol-1 and Eβ = 117 ± 4 kJ mol-1, are considerably lower than that of viscous flow at the glass transition Eα ≈ 465 kJ mol-1 as quantified from mechanical spectroscopy. Decoupling ratios of Eγ/Eα = 0.155 and Eβ/Eα = 0.255 are similar to those of sodium trisilicate glass but at considerably longer timescales. These observations imply that β- and γ-relaxations are delayed as local structural arrangements are more complex for the multi-component PTR glass. © 2008 Elsevier B.V. All rights reserved