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Vojnovskytesidae – a new family of Mississippian Rugosa (Anthozoa)

Fedorowski J., Kullmann J.

Acta Geologica Polonica

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2013

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Vol. 63, no. 4

657--679

EN

Two new species of the genus Vojnovskytes Fedorowski, 2009, namely V. marcinowskii and V. arcuatus, and a new genus, Vojnimitor, based on the new species V. proiectus, all from Mississippian strata of northern Spain, are described. Vojnovskytes variabilis (Vojnovsky-Krieger, 1934), the type species for the genus from the lowermost Viséan strata of southern Urals, also is discussed and illustrated. Characters displayed by the taxa mentioned permit introduction of a new family Vojnovskytesidae.

2

Microwave-assisted phase separation of alkali-borosilicates in the production of nanoporous glasses

Kullmann J., Enke D., Hahn T., Bauerschaefer U., Ledig L., Gai S., Bochmann A.

Optica Applicata

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2012

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Vol. 42, nr 2

255-263

EN

The influence of a hybrid thermal processing on the spinodal decomposition of sodium borosilicate glasses was investigated. The pore diameter of the resulting porous glasses is a function of the parameters of the thermal treatment. One result of this study was the inversion of the phase separation under preservation of the external shape of glass monoliths. Furthermore by using microwaves in addition to thermal radiation it was possible to generate temperature gradients in the samples and so gradients in pore size too. The glass templates were heated with microwaves in a tube furnace consisting of a resonant rectangular waveguide (TE103). Additionally the tube wall was heated by thermal radiation. The heating control was realized by steering the input power and the frequency of a 200 W semiconductor source. The regulation was performed with a HOMER 3-stub tuner, which simultaneously measured the impedance by reflected wave analysis and the actual template temperature with an IR-sensor. Various temperature-time courses of the hybrid furnace led to different pore size gradients. This was discussed by analyzing specific properties like mean pore diameter, surface area and pore volume. Further effects like the pore orientation and properties of the pore walls were determined by scanning electron microscopy and focused ion beam (FIB).

3

Characterization of pore filling of mesoporous host systems by means of positronium annihilation lifetime spectroscopy (PALS)

Kullmann J., Enke D., Thraenert S., Krause-Rehberg R., Beiner M.

Optica Applicata

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2012

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Vol. 42, nr 2

281-286

EN

Positronium annihilation lifetime spectroscopy (PALS) is an alternative method for the determination of pore sizes and pore size distributions. It is a measuring methodology which shows no limitations in the lower nanometer region and works, besides, without destruction of the sample material. It can be used for the characterization of open and closed pores. Additionally, this technology offers the possibility to obtain pore filling ratios of gases, liquids and solids precisely. Polymorphous medicaments, like acetaminophen, show different crystallization behavior within a pore system, depending on the pore size. This property can be used to control the crystalline state of the medicament and to optimize therefore the pharmaceutical use of the active substance. In this study, acetaminophen (C8H9NO2), also known as Paracetamol, is incorporated into different porous systems. The filling of the pores is realized by an acetaminophen melt at 453 K. The silica membranes are dipped into the melt, subsequently removed and cooled. Information concerning the filling ratio of the pores with the pharmaceutical was received with the help of PALS. The extended Tao-Eldrup model forms the theoretical base, taking into account the pore size sensitive annihilation properties of the ortho-positronium in matter.