Paläoproduktivitäts-Schwankungen und Veränderungen der paläozeanographischen Bedingungen im Arabischen Meer während der letzten 130.000 Jahre : rekonstruiert anhand von organischen Dinoflagellatenzysten

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Empfindlichkeitstestung von Kindern und Jugendlichen in der ersten Phase einer kieferorthopädischen Behandlung

Zur Verbesserung der Lebensqualität von Kindern und Jugendlichen, die sich einer kieferorthopädischen Behandlung unterziehen, ist in der vorliegenden Studie eine Empfindlichkeitstestung durchgeführt worden. Das Empfinden ist in Bezug auf das Schmerzverhalten und den Leidensdruck sowie auf die Motivation zur kieferorthopädischen Behandlung näher beleuchtet worden. Die Erkenntnisse geben genaue Hinweise inwieweit die Empfindlichkeit Einfluss auf die Lebensqualität hat. Die gewonnenen Anhaltspunkte sollen künftig helfen, die Lebensqualität von Patienten, die sich kieferorthopädische Maßnahmen unterziehen, zu steigern. Für die Erfassung der lebensqualitätsbeeinflussenden Erkenntnisse ist eine Befragung durchgeführt worden. Im Fragekatalog sind Hinweise über körperliche Verfassung, psychisches Befinden, soziale Beziehungen als auch funktionelle Kompetenz gesammelt worden. Die Erhebung der Empfindlichkeit wurde zu vier verschiedenen Zeitpunkten erfasst und beschreibt demzufolge ein Belastungs- und Veränderungsprofil um eine Erfolgsoption der Therapie zu erstellen. Die Resultate geben Eckdaten zur Lebensqualitätsmessung von Kindern und Jugendlichen

Octabutyl-1k2C,2k2C,3k2C,4k2C-di-µ3-oxo-1:2:3k3O;2:3:4k2O-di-µ2-phenoxy-1:2k2O;3:4k2O-diphenyoxy-1kO,4kO-tetratin(IV)

The dimeric title compound, tetrabutyldiphenoxydistannoxane, [Sn4(C4H9)8(C6H5O)4O2], adopts a ladder-type structure, featuring an almost planar inorganic framework with three four-membered Sn2O2 rings and four coplanar phenoxy groups. <br /

Understanding ring strain and ring flexibility in six - and eight-membered cyclic organometallic group 14 oxides

A simple model was developed for the approximation of ring strain energies of homo- and heterometallic, six- and eight-membered cyclic organometallic group 14 oxides and the degree of puckering of their ring conformations. The conformational energy of a ring is modelled as the sum of its angular strain components. The bending potential energy functions for the various endocyclic M&ndash;O&ndash;M&prime; and O&ndash;M&ndash;O linkages (M, M&prime;=Si, Ge, Sn) were calculated at the B3LYP/(v)TZ level of theory using H3MOM&prime;H3 and H2M(OH)2 as model compounds. For the six-membered rings, the minimum total angular contribution to ring strain, ERSGmin was calculated to decrease in the order: cyclo-(H2SiO)3 (13.0 kJ mol&minus;1)&gt;cyclo-H2Sn(OSiH2)2O (7.0 kJ mol&minus;1)&gt;cyclo-H2Ge(OSiH2)2O (4.9 kJ mol&minus;1)&gt;cyclo-H2Si(OSnH2)2O (3.4 kJ mol&minus;1)&gt;cyclo-(H2SnO)3 (1.7 kJ mol&minus;1)&gt;cyclo-H2Si(OGeH2)2O (0.8 kJ mol&minus;1)&asymp;cyclo-H2Ge(OSnH2)2O (0.7 kJ mol&minus;1)&gt;cyclo-H2Sn(OGeH2)2O (0.1 kJ mol&minus;1)&asymp;cyclo-(H2GeO)3 (0 kJ mol&minus;1). All of the six-membered rings were predicted to adopt (nearly) planar conformations (a=0.996&lt;a&lt;1). By contrast, all eight-membered rings were predicted to adopt strainless, but puckered conformations. The degree of puckering was predicted to increase in the order: cyclo-(H2SiO)4 (a=0.983)&lt;cyclo-H2Sn(OSiH2O)2SiH2 (a=0.959)&lt;cyclo-(H2SiO)2(H2SnO)2 (a=0.942)&lt; cyclo-H2Si(OSnH2O)2SiH2 (a=0.935)&lt;cyclo-(H2SnO)4 (a=0.916)&lt;cyclo-(H2GeO)4 (a=0.885). The differences in ring strain and the degree of puckering were linked to the different electronegativities of Si, Ge and Sn. The results obtained are consistent with experimental ring strain energies; reactivities towards ring opening polymerizations or ring expansion reactions and observed ring conformations of cyclic organometallic group 14 oxides

[4-(Di-tert-butyl­fluoro­silan­yl)phenyl]methanol

The asymmetric unit of the title compound, C15H25FOSi, contains two independent mol­ecules. Each of the Si atoms approximates the expected tetra­hedral geometry with Si—F bond lengths of 1.6128 (11) and 1.6068 (11) Å in the two independent mol­ecules. In the crystal, supra­molecular chains along a are found mediated by O—H⋯O hydrogen bonds

τBu₂SiF-Derivatized D₂-Receptor Ligands: The First SiFA-Containing Small Molecule Radiotracers for Target-Specific PET-Imaging

The synthesis, radiolabeling and in vitro evaluation of new silicon-fluoride acceptor (SiFA) derivatized D-2-receptor ligands is reported. The SiFA-technology simplifies the introduction of fluorine-18 into target specific biomolecules for Positron-Emission-Tomography (PET). However, one of the remaining challenges, especially for small molecules such as receptor-ligands, is the bulkiness of the SiFA-moiety. We therefore synthesized four Fallypride SiFA-conjugates derivatized either directly at the benzoic acid ring system (SiFA-DMFP, SiFA-FP, SiFA-DDMFP) or at the butyl-side chain (SiFA-M-FP) and tested their receptor affinities. We found D2-receptor affinities for all compounds in the nanomolar range (Ki(SiFA-DMFP) = 13.6 nM, Ki(SiFA-FP) = 33.0 nM, Ki(SiFA-DDMFP) = 62.7 nM and Ki(SiFA-M-FP) = 4.21 nM). The radiofluorination showed highest yields when 10 nmol of the precursors were reacted with F-18]fluoride/TBAHCO(3) in acetonitrile. After a reversed phased cartridge purification the desired products could be isolated as an injectable solution after only 10 min synthesis time with radiochemical yields (RCY) of more than 40% in the case of SiFA-DMFP resulting in specific activities >41 GBq/mu mol (>1,100 Ci/mmol). Furthermore, the radiolabeled products were shown to be stable in the injectable solutions, as well as in human plasma, for at least 90 min

Design of a Cooper pair box electrometer for application to solid-state and astroparticle physics

We describe the design and principle of operation of a fast and sensitive electrometer operated at millikelvin temperatures, which aims at replacing conventional semiconducting charge amplifiers in experiments needing low back-action or high sensitivity. The electrometer consists of a Cooper Pair box (CPB) coupled to a microwave resonator, which converts charge variations to resonance frequency shifts. We analyze the dependence of the sensitivity on the various parameters of the device, and derive their optimization. By exploiting the nonlinearities of this electrometer, and using conventional nanofabrication and measurement techniques, a charge sensitivity of a few $10^{- 7} e / \sqrt{Hz}$ can be achieved which outperforms existing single charge electrometers.Comment: 13 pages, 7 figure

Good practices for the automated production of ¹⁸F-SiFA radiopharmaceuticals

Background: The positron emitting isotope fluorine-18 (18F) possesses almost ideal physicochemical properties for the development of radiotracers for diagnostic molecular imaging employing positron emission tomography (PET). 18F in its nucleophilic anionic 18F− form is usually prepared by bombarding an enriched 18O water target with protons of various energies between 5 and 20 MeV depending on the technical specifications of the cyclotron. Large thick-target yields between 5 and 14 GBq/µA can be obtained, enough to prepare large batches of radiotracers capable to serve a considerable contingent of patients (50 + per clinical batch). The overall yield of the radiotracer however depends on the efficiency of the 18F labeling chemistry. The Silicon Fluoride Acceptor chemistry (SiFA) has introduced a convenient and highly efficient way to provide clinical peptide-based 18F-radiotracers in a kit-like procedure matching the convenience of 99mTc radiopharmaceuticals. Main body: A radiotracer’s clinical success primarily hinges on whether its synthesis can be automated. Due to its simplicity, the SiFA chemistry, which is based on isotopic exchange (18F for 19F), does not only work in a manual setup but has been proven to be automatable, yielding large batches of 18F-radiotracers of high molar activity (Am). The production of SiFA radiotracer can be centralized and the radiopharmaceutical be distributed via the “satellite” principle, where one production facility economically serves multiple clinical application sites. Clinically validated tracers such as [18F]SiTATE and [18F]Ga-rhPSMA-7/-7.3 have been synthesized in an automated synthesis unit under good manufacturing practice conditions and used in large patient cohorts. Communication of common guidelines and practices is warranted to further the dissemination of SiFA radiopharmaceuticals and to give easy access to this technology. Conclusion: This current review highlights the most recent achievements in SiFA radiopharmaceutical automation geared towards large batch production for clinical application. Best practice advice and guidance towards a facilitated implementation of the SiFA technology into new and already operating PET tracer production facilities is provided. A brief outlook spotlights the future potential of SiFA radiochemistry within the landscape of non-canonical labeling chemistries.</p