1,183 research outputs found
Relative reactivities of acetals and orthoesters in Lewis acid catalyzed reactions with vinyl ethers. A systematic investigation of the synthetic potential of acetals and orthoesters in electrophilic alkoxyalkylations of enol ethers
Comment of the use of dichloromethyl methyl ether as formylating agent
In contrast to normal alkenes, dialkylacetylenes can be formylated with dichloromethyl methyl ether (1) in the presence of 1.2 equivalents of boron trichloride. A rationalisation for the different behaviour of alkenes and alkynes arises from the NMR specktroscopic investigation of the reaction intermediates
Statistische Nachweisungen über das Immobiliar-Brandversicherungswesen im Gebiete des Königreichs Bayern diesseits des Rheins
Cycloadditionen des Triphenylallenyl-Kations mit Cyclopentadien. Studium des Reaktionsmechanismus unter stabilen Ionen-Bedingungen
Das Triphenylallenyl-Kation (5) geht mit Cyclopentadien eine konzertierte [4 + 2]- sowie eine stufenweise [2 + 2]-Cycloaddition ein. Die Reaktionsmechanismen werden durch NMR-spektro-skopische Beobachtung der intermediären Carbenium-Ionen aufgeklärt
FlĂĽssiges Schwefeldioxid als Lewis-acides Solvens fĂĽr die Alkylierung und Alkoxyalkylierung von Allylsilanen
Cerclage wiring improves biomechanical stability in distal tibia spiral fractures treated by intramedullary nailing
Open Government in den Wahlprogrammen zur Bundestagswahl 2021 - Wie steht es mit dem offenen Regierungs- und Verwaltungshandeln?
Sub-gap optical response across the structural phase transition in van der Waals layered \alpha-RuCl
We report magnetic, thermodynamic, thermal expansion, and on detailed optical
experiments on the layered compound -RuCl focusing on the THz and
sub-gap optical response across the structural phase transition from the
monoclinic high-temperature to the rhombohedral low-temperature structure,
where the stacking sequence of the molecular layers is changed. This type of
phase transition is characteristic for a variety of tri-halides crystallizing
in a layered honeycomb-type structure and so far is unique, as the
low-temperature phase exhibits the higher symmetry. One motivation is to
unravel the microscopic nature of spin-orbital excitations via a study of
temperature and symmetry-induced changes. We document a number of highly
unusual findings: A characteristic two-step hysteresis of the structural phase
transition, accompanied by a dramatic change of the reflectivity. An electronic
excitation, which appears in a narrow temperature range just across the
structural phase transition, and a complex dielectric loss spectrum in the THz
regime, which could indicate remnants of Kitaev physics. Despite significant
symmetry changes across the monoclinic to rhombohedral phase transition, phonon
eigenfrequencies and the majority of spin-orbital excitations are not strongly
influenced. Obviously, the symmetry of the single molecular layers determine
the eigenfrequencies of most of these excitations. Finally, from this combined
terahertz, far- and mid-infrared study we try to shed some light on the so far
unsolved low energy (< 1eV) electronic structure of the ruthenium
electrons in -RuCl.Comment: 22 pages, 9 figure
Kaehler Corrections for the Volume Modulus of Flux Compactifications
No-scale models arise in many compactifications of string theory and
supergravity, the most prominent recent example being type IIB flux
compactifications. Focussing on the case where the no-scale field is a single
unstabilized volume modulus (radion), we analyse the general form of
supergravity loop corrections that affect the no-scale structure of the Kaehler
potential. These corrections contribute to the 4d scalar potential of the
radion in a way that is similar to the Casimir effect. We discuss the interplay
of this loop effect with string-theoretic alpha' corrections and its possible
role in the stabilization of the radion.Comment: 8 pages, references adde
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