The Moufang condition is one of the central group theoretical conditions in Incidence Geometry, and was introduced by Jacques Tits in his famous lecture notes (1974).
About ten years ago, Norbert Knarr studied generalized quadrangles (buildings of Type ) which satisfy one of the Moufang conditions locally at one point. He then posed the fundamental question whether the group generated by the root-elations with its root containing that point is always a sharply transitive group on the points opposite this point, that is, whether this group is an elation group.
In this paper, we solve the question and a more general version affirmatively for finite generalized quadrangles.
Moreover, we show that this group is necessarily nilpotent (which was only known up till now when both Moufang conditions are satisfied for all points and lines).
In fact, as a corollary, we will prove that these groups always have to be -groups for some prime .
A ternary system, consisting of air, an air-core/dense-silica-shell core-shell particle, and liquids has been used to fabricate an inverse opal structure with low fill factor, high refractive index contrast, and reversible tuning capabilities of the bandgap spectral position. The original close-packed opal structure is a ternary self-assembled photonic crystal from monodisperse and spherical polystyrene-core/silica-shell colloidal particles with air as the void material. Calcination removed the polystyrene and converted the core-shell particles to hollow spheres with a dense shell. In a final step, liquid is infiltrated only in the voids between the hollow spheres, but does not penetrate in the shell. This allows facile and reversible tuning of the bandgap properties in an inverse opal structure. 相似文献
The second-order nonlinear optical properties of green fluorescent proteins (GFPs), such as the photoswitchable Dronpa and enhanced GFP (EGFP), have been studied at both the theoretical and experimental levels. In the case of Dronpa, both approaches are consistent in showing the rather counterintuitive result of a larger second-order nonlinear polarizability (or first hyperpolarizability, beta) for the protonated state, which has a higher transition energy, than for the deprotonated, fluorescent state with its absorption at lower energy. Moreover, the value of beta for the protonated form of Dronpa is among the highest reported for proteins. In addition to the pH dependence, we have found a wavelength dependence in the beta values. These properties are essential for the practical use of Dronpa or other GFP-like fluorescent proteins as second-order nonlinear fluorophores for symmetry-sensitive nonlinear microscopy imaging and as nonlinear optical sensors for electrophysiological processes. An accurate value of the first hyperpolarizability is also essential for any qualitative analysis of the nonlinear images. 相似文献
Extruded polystyrene (XPS) is often treated with hexabromocyclododecane (HBCD) as fire retardant (FR). Because of its aliphatic structure, HBCD is not suspected to cause formation of polybrominated dioxins upon combustion. Precursors of polybrominated dioxins, namely bromophenols, were detected during tubular furnace combustion experiments of FR-XPS in combination with sorptive enrichment on polydimethylsiloxane followed by on-line thermal desorption-capillary GC/MS. The highest concentration of mono- and tribromophenols detected were 85.9 and 3.7 mg kg(-1), respectively, at a temperature of 700 degrees C, while a temperature of 500 degrees C yielded the highest concentration of dibromophenols namely 10.4 mg kg(-1). At a combustion temperature of 900 degrees C no bromophenols were detected. 相似文献
The spins and electromagnetic properties of levels up to 3,700 keV in51V were studied by means of inelastic proton scattering. Results are discussed with reference to the many-particle shell model using effective surface delta and realistic Kuo-Brown interactions. 相似文献
A modulable tin based allylation method for the synthesis of 1,2,3-triols is described. The optimization of the reaction was aided by 1H and 119Sn low temperature NMR spectroscopic investigations, which support the formation of two cyclic intermediates after transmetallation. Depending on the nature of the Lewis acid, either syn/anti or anti/syn configured triols could be obtained with good stereocontrol. To demonstrate the value of this methodology and the resulting scaffolds, they were used to install the signature triol motifs of (?)-cleistenolide and of herbarumin I. 相似文献
This letter describes the parallel synthesis of dipeptide p-nitroanilides (1) and dipeptide diphenyl phosphonates (2), compounds that can be used as substrates and irreversible inhibitors for the rapid profiling of dipeptidyl peptidases. A polymer-assisted solution-phase synthesis was used for a rapid and clean coupling between easily available building blocks. 相似文献