Entity

Time filter

Source Type

Elsbethen, Austria

As the main objective of the present study, the morphological development of accessory zircons from four granitoids (pearl gneiss, fine-grained granite, coarse-grained gneiss, and Weinsberg granite) of the South-western Bohemian Massif was described in detail. On the one hand, this was realized by the classical approach, including a statistical evaluation of external zircon morphologies with the typology scheme. On the other hand, direct insight into the growth of single crystals was established by the production of crystal sections parallel and perpendicular to the crystallographic c-axis and by their subsequent imaging with the electron microprobe. Regarding the second method, eventual morphological trends were represented as a function of the growth rates of single crystal forms. Except for the coarse-grained gneiss, zircon crystals of the investigated granitoids show similar morphological trends according to both methods, starting with a dominant {1. 0. 0} prism and equally sized pyramids. Final crystal habit, however, is marked by the predominance of {1. 1. 0} and {2. 1. 1}. Zircon crystals from the coarse-grained gneiss run through a completely different development with a change of the prism habit from {1. 1. 0} to {1. 0. 0} and a more or less static growth of {1. 0. 1} with only slight modifications in size. Comparison of the results with data from the literature underlines the role of magma chemistry, magma temperature, and cooling rate as the main factors responsible for growth trends of accessory zircon. © 2009 Elsevier GmbH. Source


Sturm R.,Brunnleitenweg 41
Chemie in Unserer Zeit | Year: 2016

Within so-called shear zones, along which variably sized units of the earth crust are subject to a displacement, numerous chemical reactions result in the re-structuring of the rock mineralogy. This metamorphic transformation is continuously intensified from the rim to the centre of the shear zone and is chiefly controlled by pressure, temperature, and the existence of a fluid phase. As documented with the help of a concrete example chemical mass balancing in a given shear zone re- quires both the chemical analysis of educt and product and the documentation of eventual changes of rock density and rock volume. The latter changes allow a final distinction between isochemical and anisochemical transformation processes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Sturm R.,Brunnleitenweg 41
Journal of Orthoptera Research | Year: 2014

This paper examines the relationships between male body size, spermatophore size, and number of sperm per spermatophore, in four cricket species: Teleogryllus commodus, Acheta domesticus, Gryllus bimaculatus, and Gryllus assimilis. Within each species, individuals varied considerably in all three characters measured, and generally, spermatophore size, number of sperm, and body size were all correlated; i.e., ampulla diameter and sperm number per spermatophore significantly increased with body mass (p < 0.001) according to a linear regression function. Interspecific investigations found considerable differences between species: G. assimilis had the largest mean male body mass and length, largest ampullas, and highest numbers of spermatozoa per spermatophore, whilst A. domesticus had a small body mass and length, the smallest ampullas, and lowest sperm numbers. Regression analyses of all four cricket species revealed similar results as intraspecific regression computations. Hence, both intra- and interspecifically, larger males produce larger spermatophores containing more sperm, than do smaller males. These results differ from bush crickets (Tettigoniidae), where larger male body size does not necessarily correlate with larger ampullas and more sperm. Possibly male bush crickets have evolved to invest a higher proportion of their resources in the size of the nuptial gift, as opposed to number of spermatozoa. Source


The accessory glands in the genital tract of female Acheta domesticus L. (Orthoptera: Gryllidae) were investigated in detail. The glands are situated within the 7th and 8th abdominal segment and lead to the genital chamber lateral to the terminal papilla of the ductus receptaculi. The shape of the gland is characterized by a complex system of tubules, including numerous ramifications. The gland's size ranges from 2 to 4 mm. The epithelium is constructed according to a simple scheme and consists of a cuticular intima at the luminal side, one layer of gland cells, and a basallamina at the outermost side. The observed morphology of the accessory glands widely corresponds with that in other cricket species (e.g., Teleogryllus commodus). This is also true for the structure of a single gland cell, which can be subdivided into a basal part with nucleus and intracellular cisternae, as well as an apical part with all those compartments responsible for the production of the secretion. The secretion itself may be classified as lipophilic and is produced for the first time 4 to 6 days after the imaginai moult. Several endogenic functions of the secretion are discussed (lubricant for oviposition, support for introducing the tube of the spermatophore into the ductus receptaculi, etc.). © This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed. Source


Sturm R.,Brunnleitenweg 41
Zeitschrift fur Medizinische Physik | Year: 2015

Deposition of inhaled single-wall carbon nanotubes (SWCNT) and multi-wall carbon nanotubes (MWCNT) in the respiratory tract was theoretically investigated for various age groups (infants, children, adolescents, and adults). Additionally, possible effects of the inhalative flow rate on nanotube deposition were simulated for adult lungs. Theoretical computations were based on the aerodynamic diameter concept and the assumption of particles being randomly transported through a stochastic (close-to-realistic) lung structure. Deposition of nanotubes was calculated by application of well validated empirical deposition formulae, thereby considering Browian motion, inertial impaction, interception, and sedimentation as main deposition mechanisms acting on the particles. Results of the simulations clearly show that for a given inhalation scenario (sitting breathing) total, bronchial, and acinar nanotube deposition increase with subject's age, whereas extrathoracic deposition is characterized by a decrease from younger to older subjects. According to the data provided by the model, MWCNT, whose aerodynamic diameters exceed those of SWCNT by one order of magnitude, are deposited in specific respiratory compartments to a lower extent than SWCNT. A change of the physical state from sitting to heavy work results in a common decline of bronchial and extrathoracic deposition of nanotubes. Total deposition is slightly increased for SWCNT and moderately decreased for MWCNT, whereas acinar deposition is significantly increased for SWCNT and decreased for MWCNT. Based on the results of this contribution it may be concluded that SWCNT bear a higher potential as health hazards than MWCNT, because they are accumulated in sensitive lung regions with higher doses than MWCNT. © 2014. Source

Discover hidden collaborations