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.     

Carbon Dioxide: A Peagent for the Protection of Nucleophilic Centres and the Simultaneous Activation to Electrophilic Attack-Part Xii. One-Pot Conversion of 3-Methylindole into 2-Formyl-3-Methylindole

3-Methylindole is converted via treatment of intermediate lithium 2-lithio-3-methylindole-l-carboxylate with dimethylformamide or methyl formate, as formylating agent, into 2-formyl-3-methylindole in 54% overall yield in a one-pot procedure.     

Startup of superheavy element chemistry at RIKEN

A review is given on the startup of the superheavy element (SHE) chemistry at RIKEN. A gas-jet transport system for the SHE chemistry has been coupled to the gas-filled recoil ion separator GARIS at the RIKEN Linear Accelerator. The performance of the system was appraised using ²⁰⁶Fr and ²⁴⁵Fm produced in the ¹⁶⁹Tm (⁴⁰Ar, 3n) ²⁰⁶Fr and ²⁰⁸Pb (⁴⁰Ar, 3n) ²⁴⁵Fm reactions, respectively. The α particles of ²⁰⁶Fr and ²⁴⁵Fm separated with GARIS and transported by the gas-jet were identified with a rotating wheel system for α spectrometry under desired low background condition. The high gas-jet efficiencies over 80% were independent of the beam intensities up to 2 particle μA. A gas-jet coupled target system for the production of SHEs was also installed on the beam line of the RIKEN K70 AVF cyclotron. The gas-jet transport of ²⁵⁵No and ²⁶¹Rf produced in the ²³⁸U (²²Ne, 5n) ²⁵⁵No and ²⁴⁸Cm (¹⁸O, 5n) ²⁶¹Rf reactions, respectively, was conducted for the future chemical studies of ²⁶⁵Sg via the ²⁴⁸Cm (²²Ne, 5n) ²⁶⁵Sg reaction.     

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.     

Two-dimensional residual charge density distribution measurement of surface leader

The charge density distribution of the surface leader has never been measured before. Because the surface leader usually covers a long distance, and the surface potential caused by leader discharge is usually very high, this creates difficulties in measuring the potential distribution of the surface leader. In this paper, with a feedback type electrostatic probe based on a field-nullify technique, a charge density distribution scanning system is developed. A two-layer structure pipe is designed to lower the surface potential after discharge. In this way, the surface potential distribution caused by the residual charge of the leader discharge under the application voltage as high as to 40 kV can be measured. The surface charge density distribution including the leader and streamer is perfectly measured, which is in good agreement with the photograph.     

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.     

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.