Highly regio- and stereoselective ring-opening reaction of γ-alkenyl-γ-butyrolactones using allylsilanes-trimethyloxonium salt to afford methyl (e)-4,8-alkadienoates

γ-alkenyl-γ-butyrolactones reacted regio- and stereoselectively with allytrimethyl-silanes in the presence of tethyloxonium tetrafluoroborate to afford methyl (E)-4,8-alkadienoates in high yields. Synthetic utility of the present reaction was demonstrated by the synthesis of β-sinensal.     

Synthesis of isolable thiirane-2-thione (alpha-dithiolactone) from thioketene S-oxide

Reaction of di-tert-butyl thioketene S-oxide with Lawesson reagent gave 3,3-di-tert-butylthiirane-2-thione in 88% yield. Oxidation of thiirane-2-thione with m-chloroperbenzoic acid afforded 3,3-di-tert-butylthiirane-2-thione S-oxide. The reaction of thiirane-thione was described.     

Remarks on Additivity of the Holevo Channel Capacity and of the Entanglement of Formation

The purpose of this article is to discuss the relation between the additivity questions regarding the quantities (Holevo)capacityofaquantumchannelT and entanglementofformationofabipartitestate . In particular, using the Stinespring dilation theorem, we give a formula for the channel capacity involving entanglement of formation. This can be used to show that additivity of the latter for some states can be inferred from the additivity of capacity for certain channels. We demonstrate this connection for some families of channels, allowing us to calculate the entanglement cost for many states, including some where a strictly smaller upper bound on the distillable entanglement is known. Group symmetry is used for more sophisticated analysis, giving formulas valid for a class of channels. This is presented in a general framework, extending recent findings of Vidal, Dür and Cirac. We also discuss the property of superadditivity of the entanglement of formation, which would imply both the general additivity of this function under tensor products and of the Holevo capacity (with or without linear cost constraints).     

Analysis of flexural mode focusing by a semianalytical finite element method

Focusing is one of the most promising techniques for the detection of small defects in pipe works, in which guided waves including longitudinal and flexural modes are tuned so that ultrasonic energy can be focused at a target point in a pipe, and analysis of reflected waves gives information on defects such as location and size. In this paper, the focusing technique is discussed by way of a simulation of guided wave propagation in pipe by a semianalytical finite element method (SAFE). Experiments and SAFE calculations were compared for waveforms transmitted by a single transducer and received at different circumferential positions initially, and then the focusing phenomena were experimentally observed using focusing parameters obtained by calculations. Calculation and visualization were conducted to clarify focusing phenomena in pipe in investigating the potential of the focusing technique. These results show that the time-reversal idea helps in understanding focusing and that resolution of focusing is strongly affected by incident waveforms as well as the number of channels available in an experiment.     

Strain-induced regioselectivities in reactions of benzyne possessing a fused four-membered ring

[reaction: see text] A fused four-membered ring has a powerful directing ability in effecting the regioselective reactions of benzyne with ketene silyl acetal, nucleophile, and alpha-alkoxyfuran.     

Reaction of dichloromanganese(IV) Schiff-base complexes with water as a model for water oxidation in photosystem II

The dichloromanganese(IV) Schiff-base complexes Mn(N-R-3-NO₂ sal)₂Cl₂ (R = n-C₃H₇, n-C₄H₉, n-C₆H₁₃,     

13C nuclear magnetic resonance spectra of polyacrylates and their model compounds

¹³C nuclear magnetic resonance spectra (¹³C-NMR) of poly(methyl acrylates) and poly(isopropyl acrylates) of various tacticities were measured at 25.1 MHz and analyzed. ¹³C-NMR spectra of model compounds for poly(methyl acrylate), poly(acrylic acid), and poly(sodium acrylate) were also determined. The spectra of the polymers were generally complicated owing to the splittings corresponding to triad, tetrad, or pentad placements, and the assignment for each peak was difficult. Groups of peaks were analyzed by triad or tetrad placements by assuming Bernoullian or first-order Markovian statistics.     

Solvent extraction of silver and thallium picrates with poly- and bis-(crown ether)s

Summary Solvent extraction of silver and thallium picrates by new poly- and bis(crown ether)s, which contain benzo-15-crown-5 or benzo-18-crown-6 moieties, was carried out in water-chloroform system. The poly- and bis(crown ether)s showed higher extractability for both metals than the corresponding monocyclic crown ethers.Especially poly- and bis(benzo-15-crown-5) were found to be quite effective extracting agents for Tl⁺.The extraction equilibrium constants and the complexation constants for the chloroform phase were also estimated.

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Lösungsmittelextraktion von Silber- und Thalliumpikraten mit Poly- und Bis-Kronenethern

Zusammenfassung Die Extraktion der Pikrate wurde in Wasser/Chloroform mit neuen Poly- und Bis-Kronenethern durchgeführt, die Benzo-15-Krone-5- oder Benzo-18-krone-6-Komponenten enthielten. Die Poly- und Bis-Kronenether wiesen für beide Metalle eine bessere Extrahierbarkeit auf als die entsprechenden monocyclischen Kronenether. Insbesondere Poly- und Bis(benzo-15-krone-5) erwiesen sich als wirkungsvolle Extraktionsmittel für Thallium(I). Die Extraktions-Gleichgewichtskonstanten und die Komplexbildungskonstanten für die Chloroformphase wurden bestimmt.

     

Magnetic-field-induced condensation of triplons in Han Purple pigment BaCuSi2O6

Besides being an ancient pigment, BaCuSi2O6 is a quasi-2D magnetic insulator with a gapped spin dimer ground state. The application of strong magnetic fields closes this gap, creating a gas of bosonic spin triplet excitations. The topology of the spin lattice makes BaCuSi2O6 an ideal candidate for studying the Bose-Einstein condensation of triplet excitations as a function of the external magnetic field, which acts as a chemical potential. In agreement with quantum Monte Carlo numerical simulations, we observe a distinct lambda anomaly in the specific heat together with a maximum in the magnetic susceptibility upon cooling down to liquid helium temperatures.     

High sensitivity search for nu;e's from the sun and other sources at KamLAND

Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for nu;(e)'s in the energy range 8.3相似文献