Asymmetric Michael reactions of α-substituted acetates with cyclic enones catalyzed by multifunctional chiral Ru amido complexes

Well-defined 16-electron chiral Ru amido complexes, Ru[(R,R)-diamine](η⁶-arene), efficiently catalyze asymmetric Michael additions of Michael donors to cyclic enones to give adducts in high yields and with excellent ee’s. β-Ketoesters or nitroacetate as Michael donors react with 2-cyclopentenone in toluene or t-butyl alcohol containing the Ru amido catalyst (S/C=50) to afford the Michael adduct in 99% yield and with up to 92% ee. The outcome of the reaction was delicately influenced by the structures of the diamine and arene ligands as well as reaction conditions.     

Perfluorophenyl-Directed Giant Porphyrin J-Aggregates

Quadrupolar interactions of porphyrin bearing two pentafluorophenylethynyl terminals ( 1 ) drove the formation of a successive one-dimensional staircase structure, i.e., J-aggregates, to yield millimeter-length needles with a single-crystalline character in methylcyclohexane solution. In contrast, π-stacked interactions of porphyrin bearing two nonfluorinated phenyl terminals ( 2 ) formed no aggregates in solution. A spin-cast film of 1 also showed bathochromic shift of the Soret and Q bands, indicating the formation of J-aggregates. The molecular arrangement of the J-aggregates was revealed by microbeam glazing-incidence wide-angle X-ray diffraction (GIWAXD), and was in good agreement with the optimized structure generated by density functional theory (DFT) calculations.     

Synthesis of panax acetylenes: chiral syntheses of acetylpanaxydol, PQ-3 and panaxydiol

Acetylpanaxydol (1-Ac), PQ-3 (2) and panaxydiol (3) and their optical isomers were synthesized from L-(+)-diethyl tartrate. The absolute configurations of 1-Ac, 2 and 3 were determined to be 1-Ac (3R,9R,10S), 2 (9R,10S) and 3 (3R,10S), respectively, by comparisons of their optical rotations and the NMR data of their MTPA esters with those of natural products.     

Carbon dioxide: A reagent for the protection of nucleophilic centres and the simultaneous activation of alternative locations to electrophilic attack. : Part I. A new synthetic method for the 2-substitution of 1-unsubstituted indoles.

Indole was converted into several 2-substituted derivatives by using carbon dioxide both for $\text{N}$-protection and to give an intermediate carbanion stabilizing group. $\text{t}$-Butyllithium was used as a lithiating agent at the $\text{alpha}$-carbon atom of the indole enamino group. The resulting 2-substituted indole-1-carboxylic acids underwent smooth thermal decarboxylation under mild conditions. Alternatively, with longer reaction times the protecting group is lost during the reaction.     

New text indexing functionalities of the compressed suffix arrays

New text indexing functionalities of the compressed suffix arrays are proposed. The compressed suffix array proposed by Grossi and Vitter is a space-efficient data structure for text indexing. It occupies only O(n) bits for a text of length n; however it also uses the text itself that occupies bits for the alphabet . In this paper we modify the data structure so that pattern matching can be done without any access to the text. In addition to the original functions of the compressed suffix array, we add new operations search, decompress and inverse to the compressed suffix arrays. We show that the new index can find occ occurrences of any substring P of the text in O(|P|logn+occlog^εn) time for any fixed 1ε>0 without access to the text. The index also can decompress a part of the text of length m in O(m+log^εn) time. For a text of length n on an alphabet such that , our new index occupies only bits where is the order-0 entropy of the text. Especially for ε=1 the size is bits. Therefore the index will be smaller than the text, which means we can perform fast queries from compressed texts.     

Energy conversion by autonomous regulation of chaos: dynamical mechanism of loose coupling

Inspired by recent experiments of molecular motors, a dynamical systems model for a flexible machine is proposed which converts injected energy to output directional motion. The output amount is distributed broadly, and thus the coupling between input energy and output motion is loose, as in the experiments. This energy conversion is shown to be robust against the change of surrounding environment. Stability analysis on the fixed point solutions of the model is presented, which suggests that transient chaotic motion, induced by temporal three-body motion, is relevant to the energy conversion.     

Permeability of poly(1-4-piperazinediylterephthaloyl) microcapsules towards sodium chloride

Water-loaded poly(1,4-piperazinediylterephthaloyl) (PPiP) microcapsules were prepared by an interfacial polycondensation technique using piperazine and terephthaloyl dichloride as water-soluble and water-insoluble monomers, respectively. The organic solvents used were mixtures of cyclohexane and chloroform and n-hexane and chloroform in various volume ratios. The microcapsules obtained were washed successively with n-hexane, acetone, and water and fractionated into several fractions of different sizes. A suspension of each fraction and a solution of sodium chloride were mixed and the change with time in electroconductivity of the mixture was measured to estimate the rate of salt entry into the microcapsules. The permeability coefficient for the salt was calculated from the rate of salt entry. It was found that the permeability increased as the capsule size increased and was higher for the capsules prepared with n-hexane—chloroform mixtures than for those prepared with cyclohexane—chloroform mixtures. These findings were explained in terms of the density and thickness of the capsule membrane.     

Overview of coupled map lattices

Studies in coupled map lattices are briefly surveyed in connection with the papers in the present focus issue.     

Spatiotemporal chaos and noise

Low-dimensional chaotic dynamical systems can exhibit many characteristic properties of stochastic systems, such as broad Fourier spectra. They are distinguishable from stochastic processes through finite values for their dimension, Lyapunov exponents, and Kolmogorov-Sinai entropy. We discuss how these characteristic observables are modified in spatiotemporal chaotic systems like. coupled map lattices. We analyze with the help of Lyapunov concepts how the stochastic limit is approached and how these properties can be observed directly through local dimension measurements from reconstructed time series. Finally, we discuss the interaction of spatiotemporal attractors with external noise and possible connections to problems of pattern selection and stability.