Magnetic Trapping of Metastable Calcium Atoms

Metastable calcium atoms, produced in a magneto-optic trap (MOT) operating within the singlet system, are continuously loaded into a magnetic trap formed by the magnetic quadrupole field of the MOT. At MOT temperatures of 3 mK and 240 ms loading time we observe 1.1 x 10^8 magnetically trapped 3P2 atoms at densities of 2.4 x 10^8 cm^-3 and temperatures of 0.61 mK. In a modified scheme we first load a MOT for metastable atoms at a temperature of 0.18 mK and subsequently release these atoms into the magnetic trap. In this case 240 ms of loading yields 2.4 x 10^8 trapped 3P2 atoms at a peak density of 8.7 x 10^10 cm^-3 and a temperature of 0.13 mK. The temperature decrease observed in the magnetic trap for both loading schemes can be explained only in part by trap size effects.Comment: 4 figure

N-Diazeniumdiolate (NONOate) als Stickstoffmonoxid (NO)-Donatoren

In the past two decades, the chemistry of nitric oxide (NO) has become an area of high interest in biomedical research. For living organisms, nitric oxide has been shown to mediate a variety of physiological and pathophysiological processes. Diazeniumdiolates (NONOates) are known as a class of compounds that can release NO spontaneously under physiological conditions. NONOates derived from aliphatic amines such as diethylamine (DEA/NO), spermine (SPER/NO), N,N’-dimethyl-1,6-hexanediamine (MAHMA/NO) and diethylenetriamine (DETA/NO) have extensively been described and their NO-releasing properties have been studied in detail. In aqueous solution, the decomposition of NONOates follows first-order kinetics, yielding nitric oxide and the parent amine. Depending on pH, temperature and structure, the reported half-life times range from a few seconds to several hours. Figure 1. Structures of four different diazeniumdiolates. Half-life times t1/2 at pH 7.4 and 37 °C. In view of modern applications of NO-donating compounds as drugs, the release of nitric oxide should not occur spontaneously. Thus, there has been a growing interest in the synthesis of novel diazeniumdiolates with the aim to deliver NO to a specific organ or cell type. With the view to guide diazeniumdiolates to specific organs, we were interested in the synthesis of new branched polyamines. As compared to the well studied linear donors NONOates derived from branched polyamines are believed to be more stable. Due to the number of amino groups the release of NO should take place only by interaction with a natural receptor. Glycosaminoglycans (GAGs), a component of the extracellular matrix, are useful targets for polyamine-based diazeniumdiolates because the high number of sulphate and uronic acid groups in the carbohydrate polymers leads to a significant negative charge density under physiological conditions. Thus, the possible interactions of the NO donors with GAGs include electrostatic interactions such as hydrogen bonding and ion-ion interactions. Polyamine 1 was synthesized in a multistep reaction by using Michael addition and reduction methods. Compound 2 was prepared by alkylation of tris(2-aminoethyl)amine with ethelenedibromide. Starting from α-methylenglutaronitrile and ethylenediamine the tetranitrile 3 was synthesized by Michael addition reaction. Figure 2. Sructures of the branched polyamines (1, 2) and polynitrile (3) synthesized by using alkylation, reduction and Michael addition reactions. Plasma cell membranes are useful targets for hydrophobic diazeniumdiolates. However, these NO donors are not only promising NO-releasing agents, but are also useful compounds for the molecular characterization of micellar systems. Ionic micelles have long been considered as an excellent model system for studying aqueous interfaces and interfacial phenomena. In order to estimate the pH value in the Stern region of SDS micelles, we focused on the preparation of novel, surfactant-like diazeniumdiolates with a predominant hydrophobic structure. Zwitterionic diazeniumdiolates of the form RN[N(O)NO]─(CH2)2NH2+R, where R = CH3 (4), R = (CH2)3CH3 (5), R = (CH2)5CH3 (6) and R = (CH2)7CH3 (7) were synthesized by reaction of the corresponding diamine with nitric oxide. It was shown that the release of NO from the diazeniumdiolates is markedly catalyzed by anionic micelles of SDS. First–order rate constants for the decay of 4 – 7 were determined in phosphate buffer (pH 7.4) at 22 °C as function of the SDS concentration. Micellar binding constants, KSM, for the association of diazeniumdiolates with the SDS micelles were also obtained for 4 ‑ 6. The KSM values show a significant increase with increasing length of the alkyl side chains. The release of NO from 4 – 6 was further studied in presence of dioxane, cationic and nonionic surfactants. No special effect has been observed. Finally, all kinetic data were compared and discussed in terms of the particular structure of the negatively charged micelles. The utility of 5 and 6 as probes for the determination of the pH value in the Stern region of SDS micelles was demonstrated. For the zwitterionic donors 5 and 6 the dissociation of NO was studied in various buffered solutions between pH 5 and 8 at 22°C. From the pH dependence of the first–order rate constants and the rate data obtained for the surfactant–mediated decay, the pH value in the Stern region was evaluated. For a bulk phase of pH 7.4 in the Stern region a pH value of 5.9 was determined, consistent with the distribution of H+ in the vicinity of negatively charged micelles. Figure 3. Structures of the zwitterionic diazeniumdiolates 4 – 7 prepared for the study of the Stern region of sodium dodecyl sulfate (SDS) micelles. From simple kinetic studies, we could get more insight into the molecular structure of the micellar aggregates. The novel method described represents a simple and fast route for advanced studies of interfacial phenomena in micellar systems. Due to their hydrophobic structure, diazeniumdiolates such as 5 – 7 may also be useful for the preparation of novel NO-releasing polymers

Verdrängung widerständiger Lesarten? : Medien und Macht bei Jean Baudrillard und Stuart Hall

Die Arbeit behandelt einen Vergleich der Medientheorien Jean Baudrillards und Stuart Halls. Im Fokus steht die Frage nach der ‚Macht der Medien’: Versteht man Massenmedien als wichtigen Integrationsfaktor pluralistischer Gesellschaften – sie geben einen Orientierungsrahmen ‚relevanten’ Wissens an –, so sind sie gleichzeitig auch Machtfaktoren. Als radikal-apokalyptischer Theoretiker einer von medialen ‚Simulationen’ durchdrungenen Welt, sah Jean Baudrillard durch Massenmedien eine allumfassende gesellschaftliche Kontrolle eingerichtet. Aus Sicht der Cultural Studies, für deren Beschäftigung mit den Medien Stuart Hall wegweisend war und ist, treffen Medieninhalte auf ein Publikum, das immer schon über Erfahrungen, Wissen und Prägungen verfügt und daraus seine Präferenzen im Mediengebrauch ableitet – und auch entsprechende Kompetenzen ausbildet. Die Verbindung von Medien und Macht geschieht anhand des von Michel Foucault aufgestellten Modells des ‚Dipositivs’, das von Johanna Dorer für die Analyse öffentlicher Kommunikation fruchtbar gemacht worden ist. Der Blick wird hier auch auf das Internet gerichtet, durch dessen Verbreitung sich die Kommunikationslandschaft grundlegend gewandelt hat

Comprehensive machine data acquisition through intelligent parameter identification and assignment

In today’s highly competitive manufacturing environment, process data monitoring continues to be of high priority, but often relies on modern communication interfaces being provided by PLC manufacturers. This paper proposes an alternative approach in which data is acquired automatically from various PLC models through available interfaces. Multiple Machine Learning algorithms are incorporated to identify machine parameters, which are then assigned to appropriate machine information models. All functionalities can be provided by a dedicated hardware module or as software modules on IPCs. The proposed approach can be integrated into existing Industry 4.0 efforts to accelerate digitalization in challenging environments

CEDIM Forensic Disaster Analysis Group (FDA) "Volcano & Tsunami Hunga Tonga" Report No. 1

Der Vulkanausbruch im Südpazifik (Tongainseln) Mitte Januar 2022 war der weltweit stärkste seit dem Ausbruch des Pinatubo. Hunga Tonga ist ein großer unterseeischer Vulkan etwa 70 km nordwestlich von Tongatapu (Südwestpazifik). Der Vulkan besteht aus zwei kleinen Inseln, Hunga Tonga und Hunga Ha\u27apai, die durch die jüngsten Ausbrüche in den Jahren 1988, 2009 und 2014/2015 miteinander verbunden wurden. Die Eruptionssequenz begann am 20. Dezember 2021 mit einer einzelnen Eruption. Es folgten ein größeres Ereignis am 14. Januar und der Hauptausbruch am 15. Januar gegen 17:15 Uhr Ortszeit (04:15 Uhr UTC). Alle Eruptionen waren mit einem starken Überschallknall verbunden. Die Explosion der Haupteruption war über Tausende von Kilometern zu hören. Die Haupteruption löste eine große Massenbewegung aus, die als Quelle für den anschließenden Tsunami vermutet wird. Der Tsunami wurde innerhalb von 15 Minuten auf Tongatapu beobachtet und unterbrach die Energieversorgung. Der Tsunami wurde im gesamten Pazifik, im Korallenmeer und im Tasmanischen Meer mit einer Ausbreitung von bis zu 3 m gesichtet. Es kam zu schweren lokalen Überschwemmungen auf Tonga (Run-up von 2 bis 5 m) und lokal zu leichten bis mäßigen Überschwemmungen entlang des Korallenmeers (< 0,5 – 3 m) und entlang des Pazifiks (0,5 – 1,5 m). Verschiedene Inseln von Tonga wurden teilweise überflutet. Die kleinen, unbewohnten Inseln Nuku und Tau wurden vollständig erodiert. Die Überschwemmungen auf Tongatapu und Nomuka zerstörten mehrere Gebäude. Korallenriffe und Barriere-Inseln spielten eine wichtige Rolle bei der Abmilderung der Auswirkungen des Tsunami. Die größten Schäden sind auf den Bruch des Unterseekabels von Fidschi nach Tonga zurückzuführen. Die wirtschaftlichen Verluste, die mit einem solchen Ausfall verbunden sind, werden angesichts der Kosten und der Knappheit von Satellitentelefonen groß sein. Ein großes Problem stellt derzeit die Asche auf der Landebahn von Tongatapu dar, so dass Hilfsflugzeuge meist nicht landen können, um Hilfsgüter zu liefern. Zusätzliche Kosten im Zusammenhang mit den Aufräumarbeiten und der Beseitigung der Asche werden auch in der Landwirtschaft anfallen, ebenso wie mögliche Infrastrukturprobleme durch die Verunreinigung der Wasserversorgung

Preparation of (S)-tert-ButylPHOX (Oxazole, 4-(1,1-dimethylethyl)-2-[2-(diphenylphosphino)phenyl]-4,5-dihydro- (4S)-)

[No abstract

Microwave Imaging for Breast Cancer Detection:Comparison of Tomographic Imaging Algorithms using Single-Frequency and Time-Domain Data

Still more research groups are promoting microwave imaging as a viable supplement or substitution to more conventional imaging modalities. A widespread approach for microwave imaging of the breast is tomographic imaging in which one seeks to reconstruct the distributions of permittivity and conductivity in the breast. In this paper two nonlinear tomographic algorithms are compared - one is a single-frequency algorithm and the other is a time-domain algorithm

Multi-Lens Array Full-Field X-ray Microscopy

X-ray full-field microscopy at laboratory sources for photon energies above 10 keV suffers from either long exposure times or low resolution. The photon flux is mainly limited by the objectives used, having a limited numerical aperture NA. We show that this can be overcome by making use of the cone-beam illumination of laboratory sources by imaging the same field of view (FoV) several times under slightly different angles using an array of X-ray lenses. Using this technique, the exposure time can be reduced drastically without any loss in terms of resolution. A proof-of-principle is given using an existing laboratory metal-jet source at the 9.25 keV Ga Kα-line and compared to a ray-tracing simulation of the setup