Validation of a confirmatory method for the determination of residues of four nitrofurans in egg by liquid chromatography-tandem mass spectrometry with the software InterVal

A method for the detection and determination of nitrofuran derivatives in egg by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was validated with the software InterVal and can be applied for the confirmation of nitrofuran metabolites in fresh or lyophilised eggs. The validation study comprises variations in operator, storage condition, breeding, equipment and duration of sample preparation. A comprehensive overview of the robustness of the method is obtained by analysing eight samples at six concentration levels. First results of short- and medium-term investigations for stability of analytes in solution show that standard solutions of nitrofuran metabolites are stable for at least 1 year when stored at +4 degrees C in the dark. The decision limit CCalpha expressed for the underivatised metabolite is 0.05 microg kg(-1) for 3-amino-5-methyl-morpholino-2-oxazolidinone, 0.03 microg kg(-1) for 3-amino-2-oxazolidinone, 0.20 microg kg(-1) for semicarbazide and 0.22 microg kg(-1) for 1-amino-hydantoin.     

HIGHER ORDER FLEXIBILITY OF OCTAHEDRA

More than hundred years ago R. Bricard determined all continuously flexible octahedra. On the other hand, also the geometric characterization of first-order flexible octahedra has been well known for a long time. The objective of this paper is to analyze the cases between, i.e., octahedra which are infinitesimally flexible of order n > 1 but not continuously flexible. We prove explicit necessary and sufficient conditions for the orders two, three and even for all n < 8, provided the octahedron under consideration is not totally flat. Any order ≥ 8 implies already continuous flexibility, as the configuration problem for octahedra is of degree eight. This revised version was published online in August 2006 with corrections to the Cover Date.     

Interacting hadron resonance gas meets lattice QCD

We present, in the framework of the interacting hadron resonance gas, an evaluation of thermodynamical quantities. The interaction is modelled via a correction for the finite size of the hadrons. We investigate the sensitivity of the model calculations on the radius of the hadrons, which is a parameter of the model. Our calculations for thermodynamical quantities as energy and entropy densities and pressure are confronted with predictions using the lattice Quantum Chromodynamics (QCD) formalism.     

Endogenous and synthetic steroids in bovine urine – Preparation of in-house reference material,stability studies and results of a proficiency test

Within the framework of the German National Residue Control Plan a specific number of samples of animal origin have to be analysed for natural and synthetic steroids each year. As a measure of external quality control of the methods applied in routine analysis a proficiency test was carried out. To this end, in-house reference material containing incurred residues of 17α- and 17β-nortestosterone and 17α- and 17β-estradiol as well as fortified residues of 17α-methyltestosterone and 17α-trenbolone in bovine urine were produced. Before sending the proficiency test material to the participants, the homogeneity of all samples was tested and confirmed. Furthermore extensive short- and long-term stability studies were carried out.     

Baryon distributions in ultrarelativistic nucleus-nucleus collisions

We have measured distributions in transverse momentum and rapidity of protons from interactions of 14.6 GeV/nucleon²⁸Si projectiles with targets of Al and Pb. The transverse momentum spectra exhibit a thermal shape with a rapidity dependent temperature parameter. For very central or violent collisions the proton rapidity distributions exhibit the large rapidity shifts and (for Si+Al) a peak at midrapidity as required for full stopping.     

Vortex lattice transitions in YNi2B2C

We have performed extensive small-angle neutron scattering (SANS) diffraction studies of the vortex lattice in single crystal YNi₂B₂C for B‖c. High-resolution SANS, combined with a field-oscillation vortex lattice preparation technique, allows us to separate Bragg scattered intensities from two orthogonal domains and accurately determine the unit cell angle, β. The data suggest that upon increasing field there is a finite transition width where both low- and high-field distorted hexagonal vortex lattice phases, mutually rotated by 45°, coexist. The smooth variation of diffracted intensity from each phase through the transition corresponds to a redistribution of populations between the two types of domains.     

Statistical hadronization of heavy flavor quarks in elementary collisions: Successes and failures

We analyze recently compiled data on the production of open heavy flavor hadrons and quarkonia in e⁺e⁻${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ as well as pp and p-nucleus collisions in terms of the statistical hadronization model. Within this approach the production of open heavy flavor hadrons is well described with parameters deduced from a thermal analysis of light flavor hadron production. In contrast, quarkonium production in such collisions cannot be described in this framework. We point out the relevance of this finding for our understanding of quarkonium production in ultra-relativistic nucleus–nucleus collisions.     

Über zweiparametrige ebene Bewegungsvorgänge

TheBlaschke-Grünwald-map associates to each surface in the quasielliptic space a planar euclidean two-parameter motion . Using this map we find kinematic meanings of the Gaussian quasielliptic curvature and furthermore some theorems about the asymptotic motions of . The kinematic equivalent of the relation of left-conjugated tangents in points of is a regular or singular projectivity on each poleline of . This projectivities have been studied already byH. J. E. Beth andW. v.d. Woude. We show that in every position the quadratic curvature transformations of almost all one-parameter motions of are determined by .