Preparation and Crystal Structures of Ruthenium and Osmium Oxide Tetrahalides

RuOF₄ as the highest valence oxide fluoride exist as a molecular compound (a = 606.0(1), b = 836.1(1), c = 626.3(1) pm, β = 91.637(3), Z = 4; P2₁/n) as well as fluorine bridged polymer (a = 547.7(2), b = 928.5(3), c = 1252.4(3) pm, Z = 8, P2₁2₁2₁). A reproducible method for pure, deep blue OsOF₄ is given. Pure OsOF₄‐I is isostructural to the fluorine bridged polymeric RuOF₄ (a = 554.6(1), b = 955.4(2), c = 1278.4(2), Z = 8, P2₁2₁2₁). OsOF₄‐II is also a fluorine bridged polymer (a = 537.8(2), b = 1274.8(4), c = 555.2(2), β = 117.716(6)°, Z = 4, P2₁/c). OsOCl₄ again is a molecular species (a = 938.9(2), b = 561.3(1), c = 1192.0(2), β = 109.944(4)°, Z = 4, P2₁/c).     

Hilbert space representations of cross product algebras

Hilbert space representations of cross product *-algebras of the Hopf *-algebras with the coordinate algebras and of quantum vector spaces, and of with the coordinate algebras and of the corresponding quantum spheres, are investigated and classified. Invariant states on the coordinate *-algebras are described by two variants of the quantum trace.     

Abundant singularities

We show that a generic Euler flow or a generic ideal magnetostatic equilibrium contains an intricate structure of tangential discontinuities which are vortex sheets or current sheets, respectively. The discontinuities are present at all spatial scales and are dense at least in some parts of the volume occupied by the fluid. Possible implications for the energy dissipation in turbulent flows and for the structure of equilibria in tokamaks are discussed.     

Over‐Oxidation as the Key Step in the Mechanism of the MoCl5‐Mediated Dehydrogenative Coupling of Arenes

Molybdenum pentachloride is an unusually powerful reagent for the dehydrogenative coupling of arenes. Owing to the high reaction rate using MoCl₅, several labile moieties are tolerated in this transformation. The mechanistic course of the reaction was controversially discussed although indications for a single electron transfer as the initial step were found recently. Herein, based on a combined study including synthetic investigations, electrochemical measurements, EPR spectroscopy, DFT calculations, and mass spectrometry, we deduct a highly consistent mechanistic scenario: MoCl₅ acts as a one‐electron oxidant in the absence of TiCl₄ and as two‐electron oxidant in the presence of TiCl₄, but leads to an over‐oxidized intermediate in both cases, which protects it from side reactions. In the course of aqueous work‐up the reagent waste (Mo^III/IV species) acts as reducing agent generating the desired organic C?C coupling product.     

A New Method for the Preparation of Non‐Terminal Alkynes: Application to the Total Syntheses of Tulearin A and C

Lactones are known to react with the reagent generated in situ from CCl₄ and PPh₃ in a Wittig‐type fashion to give gem‐dichloro‐olefin derivatives. Such compounds are now shown to undergo reductive alkylation on treatment with organolithium reagents RLi to furnish acetylene derivatives bearing the substituent R at their termini (R=Me, n‐, sec‐, tert‐alkyl, silyl); the reaction can be catalyzed with either Cu(acac)₂ or Fe(acac)₃/1,2‐diaminobenzene. Two alkynol derivatives prepared in this way from readily accessible lactone precursors served as the key building blocks for the total syntheses of the cytotoxic marine macrolides tulearin A ( 1 ) and C ( 2 ). The assembly of these fragile targets hinged upon ring closing alkyne metathesis (RCAM) followed by a formal trans‐reduction of the resulting cycloalkynes via trans‐hydrosilylation/protodesilylation.     

Elastischer Halbraum mit unendlich langein Biegeträger

Übersicht Das Zusammenwirken von Biegeträger und Halbraum wird mit Hilfe der Fouriertransformation untersucht. Eine sin- oder cos-förmige Streifenlast ruft sowohl am Träger wie auch auf der Oberfläche des elastischen Halbraumes eine in Trägerlängsrichtung sinoder cos-förmige Verformung hervor. Wenn durch Auswertung der Einflußfläche für die Durchsenkung der Halbraumoberfläche der Zusammenhang zwischen Last- und Verformungsamplitude gewonnen ist, kann das Zusammenwirken von Träger und Halbraum für sinoder cos-förmige Streifenlast und mit der Pouriertransformation auch für andere Lasten angegeben werden.

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Elastic beam supported on an elastic half space

Summary This work ist directed toward the Fourier transform solution for the problem of the interaction between an elastic beam and an supporting elastic half space. A spatial harmonic load is applied along the longitudinal axis of an elastic beam. This results in a harmonic beam deflection, which in turn introduces a harmonic load in the elastic half space. In this manner it ist possible to relate the resulting half space deflections to the applied loads, and to resolve the applied load to beam and half space proportions. Comparison is made between this solution and the conventional solution of a beam resting on an elastic foundation.

     

Development of a Multimatrix UHPLC-MS/MS Method for the Determination of Paracetamol and Its Metabolites in Animal Tissues

Paracetamol/acetaminophen (APAP) is one of the most popular pharmacologically active substances used as an analgesic and antipyretic agent. The metabolism of this drug occurs in the liver and leads to the formation of two main metabolites—glucuronic acid and sulfate derivate. Despite the wide use of paracetamol in veterinary medicine, a handful of analytical methods were published for the determination of paracetamol residues in animal tissues. In this paper, a multimatrix method has been developed for the determination of paracetamol and two metabolites—paracetamol sulfate (PS) and p-Acetamidophenyl β-D-glucuronide (PG). A validation procedure was conducted to verify method reliability and fit purpose as a tool for analyzing acetaminophen and metabolites in muscle, liver, lung, and kidney samples from different species of animals. Established validation parameters were in agreement with acceptable criteria laid by the European legislation. The initial significant matrix effect was successfully reduced by implementing an internal standard—4-Acetamidophenyl β-D-glucuronide-d3 (PG-d3, IS). The usefulness of the developed method was verified by analyzing samples from an experiment in which paracetamol was administrated to geese.     

The Role of Formamidine Groups in Dextran Based Nonviral Vectors for Gene Delivery on Their Physicochemical and Biological Characteristics

Dextran‐formamidine esters (dextran‐N‐[(dimethylamino)methylene]‐β‐alanine ester) with different degrees of substitution (0.45–0.92) are synthesized in an one‐pot reaction. Dextran (Mw 60 000 g mol^?1) is allowed to react with unprotected beta‐alanine and iminium chloride and investigated regarding the potential as gene delivery system for the transfer of plasmid DNA. With degrees of substitution ≥ 0.63 improved DNA binding with formation of enzymatically stable complexes of about 130–160 nm with negative surface charges are obtained. These physicochemical characteristics correlated with increasing transfection rates in CHO‐K1 cells determined by a luciferase reporter gene assay in dependency of the number of formamidine residues, N/P ratios and amount of DNA. The role of the number of formamidine groups is also highlighted by in vitro cyto‐ and hemotoxicity tests under the chosen conditions. These results indicate that dextran‐formamidine esters are a very promising material for the safe and efficient gene delivery.     

Combinatorics and Algorithms for Augmenting Graphs

The notion of augmenting graphs generalizes Berge’s idea of augmenting chains, which was used by Edmonds in his celebrated solution of the maximum matching problem. This problem is a special case of the more general maximum independent set (MIS) problem. Recently, the augmenting graph approach has been successfully applied to solve MIS in various other special cases. However, our knowledge of augmenting graphs is still very limited and we do not even know what the minimal infinite classes of augmenting graphs are. In the present paper, we find an answer to this question and apply it to extend the area of polynomial-time solvability of the maximum independent set problem.