Grassmann spaces of regular subspaces

The underlying metric affine geometry, or metric projective geometry, can be recovered from Grassmann spaces associated with the family of regular subspaces of respective space. In other words, automorphisms of such Grassmann spaces are collineations witch preserve orthogonality of the respective underlying space. This generalizes results of Pra?mowska et al. (Linear Algebra Appl 430:3066–3079, 2009) and Pra?mowska and ?ynel (Adv Geom, to appear).     

Optical investigations of germanium nanoclusters – Rich SiO2 layers produced by ion beam synthesis

In this work, refractive index and extinction coefficient spectra of germanium nanoclusters – rich SiO₂ layers have been determined using variable angle spectroscopic ellipsometry (VASE) in the 250–1000 nm range. The samples were produced by Ge⁺ ion implantation into SiO₂ layers on Si substrates and subsequent annealing at temperatures from 700 to 1100 °C. It is known from previous investigations of similar samples that the Ge nanoclusterization process starts already at 800 °C and spherical Ge nanocrystallites 5–8 nm in diameter are observed in the SiO₂ layers after annealing for 1 h at even higher temperatures of 1000–1100 °C. Rutherford backscattering spectrometry (RBS) was employed to measure the Ge atom concentration depth profiles in the studied samples. The RBS results helped us choose realistic models for the VASE analysis which were necessary for a proper interpretation of the VASE data. It has been found that the refraction index value for the SiO₂/Si layer increases after Ge implantation. This effect can be explained by a defect-dependent compaction of ion-bombarded layers. A band’s tail in the extinction coefficient spectra for all the samples is observed which originates from a strong ultraviolet absorption band at 6.8 eV due to a Germanium Oxygen-Deficiency Center (GeODC) and/or a Ge-E’center in SiO₂. The annealing process results in the emergence of weaker extinction coefficient bands in the 400–600 nm region, associated with direct band-to-band transitions in Ge nanostructures. Transformation of these bands, including their blue-shift with the increasing annealing temperature could be explained via a quantum-confinement mechanism, by size and structural changes in Ge nanostructures.     

Boron doped carbon nanotubes via ceramic catalysts

A facile metal catalyst free route to synthesize boron doped (0.6%–1.0%) carbon nanotubes via ceramic nanowires in which the formation of the nanowires (probably serving as templates), the carbon nanotubes and their doping all occur unanimously in the reaction, is presented.

     

Selfinjective algebras without short cycles of indecomposable modules

We describe the structure of finite dimensional selfinjective algebras over an arbitrary field without short cycles of indecomposable modules.     

Characterization of thermal properties of goat milk fat and goat milk chocolate by using DSC,PDSC and TGA methods

Journal of Thermal Analysis and Calorimetry - A relatively unexplored goat’s milk fat and goat’s milk chocolate were investigated to enhance thermal properties of both. Differential...     

Synthesis and properties of ferro- and antiferroelectric esters with a chiral centre based on (S)-(+)-3-octanol

A homologous series of chiral three ring esters were synthesised and their properties were studied. The materials possess an antiferroelectric phase (SmC_A*) or/and a ferroelectric phase (SmC*), which was confirmed by observations of microscopic textures using a polarising optical microscope. The phase transition temperatures and enthalpies were checked by differential scanning calorimetry. The helical pitch was measured by a spectrophotometry method. For all cases the helix is right-handed, in the antiferroelectric phase the helical pitch increases with temperature, and in the ferroelectric phase the helical pitch is short.     

Hydroxy lactones with the gem-dimethylcyclohexane system – Synthesis and antimicrobial activity

Two new lactones comprising the gem-dimethylcyclohexane ring: 2-chloro-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one and 2-bromo-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one as well as the already known 2-iodo-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one, were obtained from (6,6-dimethylcyclohex-2-en-1-yl)acetic acid. These lactones were used as substrates for the screening of biotransformation by whole cells of nine fungal strains (Fusarium species, Syncephalastrum racemosum and Cunninghamella japonica). Some of these microorganisms (mainly Fusarium species) transformed all three lactones during the hydrolytic dehalogenation into 2-hydroxy-5,5-dimethyl-9-oxabicyclo[4.3.0]nonan-8-one. It is worth noting that two microorganisms (Fusarium culmorum and Fusarium scirpi) converted iodolactone with very high enantioselectivity (75.1% and 91.6%, respectively). The (+) isomer of hydroxy lactone was preferred. At the last step the hydroxy lactone obtained during biotransformation was examined for its biological activity against bacteria, yeasts and fungi. It was found that this compound inhibits growth of some tested microorganisms.     

Faddeev Calculations of Breakup Reactions with Realistic Experimental Constraints

We present a method to integrate predictions from a theoretical model of a reaction with three bodies in the final state over the region of phase space covered by a given experiment. The method takes into account the true experimental acceptance, as well as variations of detector efficiency, and eliminates the need for a Monte-Carlo simulation of the detector setup. The method is applicable to kinematically complete experiments. Examples for the use of this method include several polarization observables in dp breakup at 270MeV. The calculations are carried out in the Faddeev framework with the CD Bonn nucleon-nucleon interaction, with or without the inclusion of an additional three-nucleon force.     

Level Dynamics and Universality of Spectral Fluctuations

The spectral fluctuations of quantum (or wave) systems with a chaotic classical (or ray) limit are mostly universal and faithful to random-matrix theory. Taking up ideas of Pechukas and Yukawa we show that equilibrium statistical mechanics for the fictitious gas of particles associated with the parametric motion of levels yields spectral fluctuations of the random-matrix type. Previously known clues to that goal are an appropriate equilibrium ensemble and a certain ergodicity of level dynamics. We here complete the reasoning by establishing a power law for the dependence of the mean parametric separation of avoided level crossings. Due to that law universal spectral fluctuations emerge as average behavior of a family of quantum dynamics drawn from a control parameter interval which becomes vanishingly small in the classical limit; the family thus corresponds to a single classical system. We also argue that classically integrable dynamics cannot produce universal spectral fluctuations since their level dynamics resembles a nearly ideal Pechukas–Yukawa gas.     

Isomeric decay of 67Fe --Evidence for deformation

Decay-spectroscopy study of the ^67mFe isomer has been performed at GANIL. This isomer is found to have an energy of 387 keV and a half-life of 75(21) μs. An intermediate excited state is introduced at 367 keV. The results are interpreted in terms of various nuclear models, and a deformed shape is inferred for ⁶⁷Fe. Received: 12 August 2002 / Accepted: 12 September 2002 / Published online: 17 January 2003 RID="a" ID="a"e-mail: sawicka@ganil.fr and sawicka@zsjlin.igf.fuw. edu.pl Communicated by W. Henning