Sterine in Weidegräsern

During the course of investigations concerned with a cattle disease (Weidekrankheit) in Austrian alpine regions, it became of interest to examine the sterol fractions of some typical grasing plants, since it seemed possible that a biological connection exists between the phytosterols, Vitamin D and related compounds and the cause of the Weidekrankheit.The sterol contents of eight different species of Austrian alpine grasses especially of Trisetum flavescens, were studied by gas-liquid chromatography and mass spectrometry. All contained sitosterol as the main component, besides cholesterol, campesterol, stigmasterol, ⁷-cholestenol and ^{7,24 (28)}-stigmastadienol.The aim of this examination was to establish whether there is an influence of fertilizing on the content of the above mentioned compounds: no remarkable difference between the sterol contents of fertilized and non-fertilized grasses could be found.     

Cardiovascular regulation during sleep quantified by symbolic coupling traces

Sleep is a complex regulated process with short periods of wakefulness and different sleep stages. These sleep stages modulate autonomous functions such as blood pressure and heart rate. The method of symbolic coupling traces (SCT) is used to analyze and quantify time-delayed coupling of these measurements during different sleep stages. The symbolic coupling traces, defined as the symmetric and diametric traces of the bivariate word distribution matrix, allow the quantification of time-delayed coupling. In this paper, the method is applied to heart rate and systolic blood pressure time series during different sleep stages for healthy controls as well as for normotensive and hypertensive patients with sleep apneas. Using the SCT, significant different cardiovascular mechanisms not only between the deep sleep and the other sleep stages but also between healthy subjects and patients can be revealed. The SCT method is applied to model systems, compared with established methods, such as cross correlation, mutual information, and cross recurrence analysis and demonstrates its advantages especially for nonstationary physiological data. As a result, SCT proves to be more specific in detecting delays of directional interactions than standard coupling analysis methods and yields additional information which cannot be measured by standard parameters of heart rate and blood pressure variability. The proposed method may help to indicate the pathological changes in cardiovascular regulation and also the effects of continuous positive airway pressure therapy on the cardiovascular system.     

A Structural View on Medicinal Chemistry Strategies against Drug Resistance

The natural phenomenon of drug resistance is a widespread issue that hampers the performance of drugs in many major clinical indications. Antibacterial and antifungal drugs are affected, as well as compounds for the treatment of cancer, viral infections, or parasitic diseases. Despite the very diverse set of biological targets and organisms involved in the development of drug resistance, the underlying molecular mechanisms have been identified to understand the emergence of resistance and to overcome this detrimental process. Detailed structural information on the root causes for drug resistance is nowadays frequently available, so next‐generation drugs can be designed that are anticipated to suffer less from resistance. This knowledge‐based approach is essential for fighting the inevitable occurrence of drug resistance.     

Recycled injection-molded and fibre-reinforced polyethylene/polypropylene

In this presentation, we are concerned with the fabrication and characterization of samples of compression-molded and injection-molded recycled polyethylene, with, in some cases, addition of cellulose fibre. We wish to know what is the performance of such plastics, as compared to the virgin materials and what is the effect of added fibre in both molding modes.     

New facile tandem route to oxo- and thioxo[1,2,4]triazolo[1,5-a]pyridinium salts

2-Arylsulfanyl- and benzylsulfanylpyridinium N-arylimides (2), easily available from tetrazolo[1,5-b]pyridinium salts (1), participate in 1,3-dipolar cycloaddition with aryl isothiocyanates and aryl isocyanates to result in formation of fused thioxo- and oxo[1,2,4]triazolium salts (5 and 12), respectively. This transformation is interpreted as a regular 1,3-cycloaddition followed by spontaneous elimination of the aryl- or benzylsulfanyl group. Formation of these triazolium salts can be followed--under appropriate reaction conditions--by ring-opening reactions to afford some new triazolyldienes (6). Recognition of the intermediate participation of the thiolate anion along the pathway 1 --> 5 allowed elaboration of a simple procedure to 5 implying a tandem reaction sequence.     

Cosserat Operators of Higher Order

A higher order version of Cosserat Operators is introduced. With a compactness result (the proof of which we can only sketch here, for details see Riedl in Cosserat operators of higher order and applications, PhD thesis, University of Bayreuth, 2010) based on a regularization property of these operators we gain insight to invertibility of the operator div : ${\underline{H}^{m,q}_0 (G) \rightarrow H^{m-1,q}_{0,0} (G)}$ , where ${m \in \mathbb{N}, 1 < q < \infty}$ and ${G \subset \mathbb{R}^n}$ is a bounded domain with sufficiently smooth boundary. As an application, we get a very simple and effective method of treating higher order generalizations of Stokes’ system.     

Unexpected ring transformation to pyrrolo[3.2-b]pyridine derivatives. Fused azolium salts. 22

2-Arylsulfanyl and 2-benzylsulfanylpyridinium N-arylimides (2) easily prepared from 3-aryltetrazolopyridinium salts (1) with aryl and benzylthiolates, respectively, reacted with various dipolarophiles yielding cycloadducts that underwent transformation to give tetrahydropyrrolo[3,2-b]pyridines (5, 6, and 8) in good yields. A similar rearrangement (formation of 15) was also observed in the case of parent derivatives being unsubstituted in position 2 (12). The abscence of any significant solvent effect, comparison of the sulfur and non-sulfur analogues, as well as the stereoselective nature of the observed ring transformation seem to support a sigmatropic mechanism. Structure elucidation of the products has been carried out by single-crystal X-ray diffraction and (1)H NMR experiments.     

Wavelength-tunable organic solid-state distributed-feedback laser

We report on a wavelength-tunable organic solid-state laser based on a second-order distributed-feedback (DFB) resonator design with the guest–host system Alq₃:DCM2 as the gain medium. The laser wavelength can be shifted from 608.9 to 646.5 nm by varying the grating period of the Bragg reflector. This allows the characterization of laser parameters for a large wavelength region on a single sample. The laser threshold and output characteristics are measured for different laser wavelengths. A minimum threshold for laser activity occurs at a lasing wavelength of 633 nm, giving the spectral position of the gain maximum. PACS 42.70.Jk; 78.45.+h; 78.66.Qn