Crossed Products for Weak Hopf Algebras

Weak crossed products by a weak bialgebra are defined. The resulting structure is not that of a unital algebra but an associative algebra with preunit. A general formula of such a product is given in terms of a weak 2-cocycle and a weak measuring. The relation with weak cleft extensions is studied. Equivalences of weak crossed products are defined and are related to gauge transformations. A relation between cleaving maps is described in terms of gauge transformations.     

Terahertz radiation-induced magnetoresistance oscillations of a high-density and high-mobility two-dimensional electron gas

The terahertz response of a high-density and high-mobility two-dimensional electron gas in 13-nm GaAs quantum wells at frequencies of 0.7 and 1.63 THz has been investigated. Terahertz radiation-induced magnetoresistance oscillations have been discovered. The oscillation maxima coincide with the harmonics of cyclotron resonance. It has been shown that a large number of harmonics (up to the ninth) appear under irradiation at a frequency of 0.7 THz. In this case, the effect is the analogue of microwave-induced oscillations. At a higher frequency, the oscillation amplitude decreases drastically with an increase in the harmonic number. This indicates a transition to the regime of ordinary cyclotron harmonics.     

Revisiting the European sovereign bonds with a permutation-information-theory approach

In this paper we study the evolution of the informational efficiency in its weak form for seventeen European sovereign bonds time series. We aim to assess the impact of two specific economic situations in the hypothetical random behavior of these time series: the establishment of a common currency and a wide and deep financial crisis. In order to evaluate the informational efficiency we use permutation quantifiers derived from information theory. Specifically, time series are ranked according to two metrics that measure the intrinsic structure of their correlations: permutation entropy and permutation statistical complexity. These measures provide the rectangular coordinates of the complexity-entropy causality plane; the planar location of the time series in this representation space reveals the degree of informational efficiency. According to our results, the currency union contributed to homogenize the stochastic characteristics of the time series and produced synchronization in the random behavior of them. Additionally, the 2008 financial crisis uncovered differences within the apparently homogeneous European sovereign markets and revealed country-specific characteristics that were partially hidden during the monetary union heyday.     

Oxidative Cyclization of 2-Arylhydrazonothioacetamides

Intramolecular oxidative cyclization of 2-arylhydrazonothioacetamides was studied, and applicability limits of this reaction for the synthesis of 2-aryl-1,2,3-thiadiazol-5(2H)-imines were determined.     

Heterocyclic Thiones and Their Analogs in 1,3-Dipolar Cycloaddition Reactions: IV. Reactions of 4-Aryl-2-phenyl-1,2-dihydrophthalazine-1-thiones with Nitrile Imides

4-Aryl-2-phenyl-1,2-dihydrophthalazine-1-thiones react with nitrile imides according to the [3 + 2]-cycloaddition pattern to give phthalazinespirothiadiazoles. The reaction occurs regioselectively at the exocyclic C=S bond.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 3, 2005, pp. 462–467.Original Russian Text Copyright © 2005 by Budarina, Plotnikov, Labeish, Bel’skii, Galishev.For communication III, see [1].     

Unusual Metal–Metal Bonding in a Dinuclear Pt–Au Complex: Snapshot of a Transmetalation Process

The dinuclear Pt–Au complex [(CNC)(PPh₃)Pt Au(PPh₃)](ClO₄) ( 2 ) (CNC=2,6‐diphenylpyridinate) was prepared. Its crystal structure shows a rare metal–metal bonding situation, with very short Pt–Au and Au–C_ipso(CNC) distances and dissimilar Pt–C_ipso(CNC) bonds. Multinuclear NMR spectra of 2 show the persistence of the Pt–Au bond in solution and the occurrence of unusual fluxional behavior involving the [Pt^II] and [Au^I] metal fragments. The [Pt^II]??? [Au^I] interaction has been thoroughly studied by means of DFT calculations. The observed bonding situation in 2 can be regarded as a model for an intermediate in a transmetalation process.     

Insertion of Isocyanides into N−Si Bonds: Multicomponent Reactions with Azines Leading to Potent Antiparasitic Compounds

Trimethylsilyl chloride is an efficient activating agent for azines in isocyanide‐based reactions, which then proceed through a key insertion of the isocyanide into a N?Si bond. The reaction is initiated by N activation of the azine, followed by nucleophilic attack of an isocyanide in a Reissert‐type process. Finally, a second equivalent of the same or a different isocyanide inserts into the N?Si bond leading to the final adduct. The use of distinct nucleophiles leads to a variety of α‐substituted dihydroazines after a selective cascade process. Based on computational studies, a mechanistic hypothesis for the course of these reactions was proposed. The resulting products exhibit significant activity against Trypanosoma brucei and T. cruzi, featuring favorable drug‐like properties and safety profiles.     

Morphological Profiling Identifies the Motor Protein Eg5 as Cellular Target of Spirooxindoles

Oxindoles and iso-oxindoles are natural product-derived scaffolds that provide inspiration for the design and synthesis of novel biologically relevant compound classes. Notably, the spirocyclic connection of oxindoles with iso-oxindoles has not been explored by nature but promises to provide structurally related compounds endowed with novel bioactivity. Therefore, methods for their efficient synthesis and the conclusive discovery of their cellular targets are highly desirable. We describe a selective Rh^III-catalyzed scaffold-divergent synthesis of spirooxindole–isooxindoles and spirooxindole–oxindoles from differently protected diazooxindoles and N-pivaloyloxy aryl amides which includes a functional group-controlled Lossen rearrangement as key step. Unbiased morphological profiling of a corresponding compound collection in the Cell Painting assay efficiently identified the mitotic kinesin Eg5 as the cellular target of the spirooxindoles, defining a unique Eg5 inhibitor chemotype.