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Starting from (MeO)3SiCH2Cl (10) and Ph2(H)SiCH2OH (16), respectively, the (hydroxymethyl)diphenyl(piperidinoalkyl)silanes (HOCH2)Ph2Si(CH2)2NC5H10 (6) and (HOCH2)Ph2Si(CH2)3NC5H10 (8) have been synthesized [10→Ph2(MeO)SiCH2Cl (11)→Ph2(CH2=CH)SiCH2Cl (12)→Ph2(CH2=CH)SiCH2OAc (13)→Ph2(CH2=CH)SiCH2OH (14)→Ph2(CH2=CH)SiCH2OSiMe3 (15)→6; 16→Ph2(H)SiCH2OSiMe3 (17)→8; NC5H10 = piperidino]. N-Quaternization of 6 and 8 with MeI gave the corresponding methiodides 7 and 9, respectively. As shown by IR-spectroscopic studies, compounds 6 and 8 form intramolecular O-H···N hydrogen bonds in solution (CCl4). In the crystal, 6 (space group Pna21; two crystallographically independent molecules) also forms intramolecular O-H···N hydrogen bonds whereas 8 (space group P1̅) forms intermolecular O-H···N hydrogen bonds leading to the formation of centrosymmetric dimers (single-crystal X-ray diffraction studies). The (hydroxymethyl) silanes 6-9 and the related silanols (HO)Ph2Si(CH2)2NC5H 10 (sila-pridinol; 1), sila-pridinol methiodide (2), (HO)Ph2Si(CH2)3NC5H10 (sila-difenidol; 3) and sila-difenidol methiodide (4) were investigated for their antimuscarinic properties. In functional pharmacological experiments as well as in radioligand competition studies, all compounds behaved as simple competitive antagonists at muscarinic M1-, M2-, M3- and M4-receptors. In general, the silanols 1-4 displayed higher receptor affinities (up to 100-fold) than the corresponding (hydroxymethyl) silanes 6-9 . In the (hydroxymethyl)silane series, compound 7 was found to be the most potent muscarinic antagonist [pA2/pKi= 8,71/8,6 (M1), 8,23/7,8 (M2), 8,19/7,8 (M3); pKi = 8,2 (M4)]. In the silanol series, the related compound 2 showed the most interesting antimuscarinic properties [pA2/pKi = 10,37/9,6 (M1), 8,97/8,8 (M2), 9,08/8,8 (M3); pKi = 9,4 (M4)].
Using the NA49 main TPC, the central production of hyperons has been measured in CERN SPS Pb - Pb collisions at 158 GeV c-1. The preliminary ratio, studied at 2.0 < y < 2.6 and 1 < pT < 3 GeV c-1, equals ~ (13 ± 4)% (systematic error only). It is compatible, within errors, with the previously obtained ratios for central S + S [1], S + W [2], and S + Au [3] collisions. The fit to the transverse momentum distribution resulted in an inverse slope parameter T of 297 MeV. At this level of statistics we do not see any noticeable enhancement of hyperon production with the increased volume (and, possibly, degree of equilibration) of the system from S + S to Pb + Pb. This result is unexpected and counterintuitive, and should be further investigated. If confirmed, it will have a significant impact on our understanding of mechanisms leading to the enhanced strangeness production in heavy-ion collisions.
Preliminary data on phi production in central Pb + Pb collisions at 158 GeV per nucleon are presented, measured by the NA49 experiment in the hadronic decay channel phi - K+K-. At mid-rapidity, the kaons were separated from pions and protons by combining dE/dx and time-of-flight information; in the forward rapidity range only dE/dx identification was used to obtain the rapidity distribution and a rapidity-integrated mt-spectrum. The mid-rapidity yield obtained was dN/dy = 1.85 ± 0.3 per event; the total phi multiplicity was estimated to be 5.0 ± 0.7 per event. Comparison with published pp data shows a slight, but not very significant strangeness enhancement.
Lambda and Antilambda reconstruction in central Pb+Pb collisions using a time projection chamber
(1997)
The large acceptance time projection chambers of the NA49 experiment are used to record the trajectory of charged particles from Pb + Pb collisions at 158 GeV per nucleon. Neutral strange hadrons have been reconstructed from their charged decay products. To obtain distributions of Λ, and Ks0 in discrete bins of rapidity, y, and transverse momentum, pT, calculations have been performed to determine the acceptance of the detector and the efficiency of the reconstruction software as a function of both variables. The lifetime distributions obtained give values of cτ = 7.8 ± 0.6 cm for Λ and cτ = 2.5 ± 0.3 cm for Ks0, consistent with data book values.
Faunistischer Artenschutz in Waldgebieten : dargestellt für das NSG "Borntal" im Ziegelrodaer Forst
(1999)
Das Naturschutzgebiet (NSG) "Borntal" wurde am 30. März 1961 vom Ministerium für Landwirtschaft, Erfassung und Forstwirtschaft der DDR unter Schutz gestellt. Damit wurde vor allem das Ziel verbunden, einen einmaligen Komplex naturnaher Waldgesellschaften und Standortformen, wie er in derart konzentrierter Ausprägung nirgends sonst im Ziegelrodaer Forst und dessen Umgebung zu finden ist, zu sichern. Analysen zur Bedeutung des Gebietes für die Tierwelt traten hinter diesem Aspekt stets deutlich zurück und spielten vom Zeitpunkt der Ausweisung an (Hentschel et al. 1983) bis heute (Die Naturschutzgebiete …1997) lediglich eine untergeordnete Rolle.
In den vorangehenden Kapiteln wurde die besondere Charakteristik sowie die bundes- und europaweite Bedeutung des Schutzgebietssystems um die Mansfelder Seen und vordringlich des ehemaligen Salzigen Sees herausgestellt. Es wurde ebenfalls deutlich, dass die Wiederentstehung des Salzigen Sees einen schwerwiegenden Eingriff in den bestehenden Gebietswasserhaushalt darstellt, dessen langfristige Konsequenzen noch nicht in allen Aspekten absehbar sind. Welche Auswirkungen kann dieses Vorhaben nun auf die hoch schutzwürdige Fauna und Flora haben und welche Vorkehrungen müssen getroffen werden, damit die Chancen für den Arten- und Biotopschutz, die der Wiederentstehung des Sees zweifellos innewohnen, zum Tragen kommen?
Two-pion correlation functions in Au+Au collisions at sqrt[sNN] = 130 GeV have been measured by the STAR (solenoidal tracker at RHIC) detector. The source size extracted by fitting the correlations grows with event multiplicity and decreases with transverse momentum. Anomalously large sizes or emission durations, which have been suggested as signals of quark-gluon plasma formation and rehadronization, are not observed. The Hanbury Brown-Twiss parameters display a weak energy dependence over a broad range in sqrt[sNN].
The first measurements of light antinucleus production in Au+Au collisions at the Relativistic Heavy-Ion Collider are reported. The observed production rates for d-bar and 3He-bar are much larger than in lower energy nucleus-nucleus collisions. A coalescence model analysis of the yields indicates that there is little or no increase in the antinucleon freeze-out volume compared to collisions at CERN SPS energy. These analyses also indicate that the 3He-bar freeze-out volume is smaller than the d-bar freeze-out volume.