Bound fluxon pair in one-dimensional SQUID array

We propose a one-dimensional array of superconducting quantum interference devices (SQUIDs) composed of three asymmetrically positioned Josephson junctions to realize a discrete double sine-Gordon (DSG) model. Two fluxons in this SQUID array attract each other and form bound states with internal oscillation modes. We conduct numerical simulations of a discrete DSG equation, and show that the period of the internal oscillation of a moving fluxon pair exhibits relativistic time dilation except near the speed of light. We also show that driving with a pure alternating current causes progressive motion of the bound fluxon pair even in the presence of dissipation.     

Further studies on the constituents of the gorgonian octocoral Pseudopterogorgia elisabethae collected in San Andrés and Providencia islands, Colombian Caribbean: isolation of a putative biosynthetic intermediate leading to erogorgiaene

Chemical investigations of the MeOH-CH₂Cl₂ extract of Pseudopterogorgia elisabethae specimens collected in the islands of San Andrés and Providencia, Colombian Caribbean, yielded four new diterpenes (1, 3, 5, 7) along with seco-pseudopterosin J (8), and amphilectosins A (9) and B (10). The structures of the new compounds were established through spectral studies as an elisabethatriene analog named elisabethatrienol (1), 10-acetoxy-9-hydroxy- and 9-acetoxy-10-hydroxy-amphilecta-8,10,12,14-tetraenes (isolated as an interconverting mixture) (3), amphilecta-8(13),11,14-triene-9,10-dione (5), and a seco-pseudopterosin 7-O-α-l-fucopyranoside named seco-pseudopterosin K (7). Elisabethatrienol can be regarded as a biosynthetic intermediate leading to erogorgiaene.     

Photochemical stitching of a tubularly assembled hexabenzocoronene amphiphile by dimerization of coumarin pendants

A coumarin-appended amphiphilic hexa-peri-hexabenzocoronene (1) self-assembled to form graphitic nanotubes. Upon irradiation of lambda > 300 nm, the nanotubes in the solid state and suspension both underwent dimerization of the coumarin pendants, affording covalently stitched nanotubes, which were hardly soluble in CHCl3, a good solvent of 1. In contrast, a thin film cast from a homogeneous solution of 1 was intact to photoirradiation. Owing to the reversible nature of the photochemical stitching, both negative and positive patterns of the graphitic nanotubes were developed on a silicon substrate by a lithographic post processing.     

Hyosgerin, a new optically active coumarinolignan, from the seeds of Hyoscyamus niger

Hyosgerin, a new optically active coumarinolignan, has been isolated and characterized along with three other coumarinolignans, venkatasin, cleomiscosin A and cleomiscosin B, from the seeds of Hyoscyamus niger L. The structure was determined on the basis of spectroscopic analysis and chemical conversion. The optical properties and absolute stereochemistry of these coumarinolignans have also been studied and discussed.     

Linear-type S-bridged triruthenium complexes with aliphatic aminothiolate ligands: synthesis, characterization, and properties

Treatment of [RuCl(2)(DMSO)(4)] with 2-aminoethanethiol (Haet) in ethanol gave a dicationic triruthenium complex, [Ru[Ru(aet)(3)](2)]Cl(2) ([1]Cl(2)). Complex [1]Cl(2) was also obtained by treatment of RuCl(3).nH(2)O with excess Haet in water. When [1](2+) was chromatographed on a cation-exchange column of SP-Sephadex C-25, meso (DeltaLambda) and racemic (DeltaDelta/LambdaLambda) isomers of the corresponding tricationic complex, [Ru[Ru(aet)(3)](2)](3+) ([2](3+)), were eluted with aqueous NaNO(3). The racemic isomer of [2](3+) was optically resolved into DeltaDelta and LambdaLambda isomers by using [Sb(2)(R,R-tartrato)(2)](2-) as a resolving agent. The molecular structures of DeltaLambda- and DeltaDelta/LambdaLambda-[2](NO(3))(3) were determined by X-ray crystallography. In these complexes, the central Ru atom is coordinated by six thiolato groups from two terminal fac-(S)-[Ru(aet)(3)] units in an octahedral geometry, forming a linear-type S-bridged triruthenium structure. The spectroelectrochemical studies on the electronic absorption and CD spectra, together with the electrochemical studies, demonstrated that [1](2+) and [2](3+) are interconvertible with each other through a one-electron redox process, retaining the chirality of the triruthenium structure. Their electronic structures were investigated on the basis of EPR and magnetic susceptibility measurements, which indicated that [1](2+) and [2](3+) have spin ground states of S(t) = 0 and S(t) = 1/2, respectively. The corresponding L-cysteinato complex, [Ru[Ru(L-cys-N,S)(3)](2)](3-), which was formed from RuCl(3).nH(2)O and excess L-cysteine (L-H(2)cys) in water followed by air oxidation, is also presented.     

A short and efficient asymmetric synthesis of komaroviquinone

An asymmetric total synthesis of komaroviquinone (1), which is a natural product isolated from Dracocephalum komarovi and shows novel potent trypanocidal activity, was achieved in five steps from the known starting materials. The synthetic route is shorter and more efficient than the reported methods and also useful for the scale-up synthesis.     

Use of Side‐Chain Incompatibility for Tailoring Long‐Range p/n Heterojunctions: Photoconductive Nanofibers Formed by Self‐Assembly of an Amphiphilic Donor–Acceptor Dyad Consisting of Oligothiophene and Perylenediimide

To tailor organic p/n heterojunctions with molecular‐level precision, a rational design strategy using side‐chain incompatibility of a covalently connected donor–acceptor (D–A) dyad has been successfully carried out. An oligothiophene–perylenediimide dyad, when modified with triethylene glycol side chains at one terminus and dodecyl side chains at the other ( 2 Amphi ), self‐assembles into nanofibers with a long‐range D/A heterojunction. In contrast, when the dyad is modified with dodecyl side chains at both termini ( 2 Lipo ), ill‐defined microfibers result. In steady‐state measurements using microgap electrodes, a cast film of the nanofiber of 2 Amphi displays far better photoconducting properties than that of the microfiber of 2 Lipo . Flash‐photolysis time‐resolved microwave conductivity measurements, in conjunction with transient absorption spectroscopy, clearly indicate that the nanofiber of 2 Amphi intrinsically allows for better carrier generation and transport properties than the microfibrous assembly of 2 Lipo .     

PLD of X7R for thin film capacitors

Thin film capacitors with a thickness of 200 nm were prepared on SrTiO₃ (1 0 0), (1 1 0) and (1 1 1) single crystal substrates at a temperature of 973 K by pulsed laser deposition (PLD) using a KrF excimer laser in an O₂-O₃ atmosphere with a gas pressure of 1 Pa using an X7R sintered target. As a result, perovskite BaTiO₃ solid solution films were obtained. In the X7R thin films on (1 0 0) and (1 1 0) SrTiO₃, only diffraction peaks with strong intensities from BaTiO₃ (1 0 0) and (1 1 0), respectively, were observed. X7R films on SrTiO₃ (1 1 1) were grown epitaxially oriented to the crystal plane direction of the substrate by inserting an initial homoepitaxial SrTiO₃ layer with a thickness of 4 nm. The X7R/SrTiO₃ film capacitors yielded a large volumetric efficiency of 50 μF/mm³ and a temperature coefficient of capacitance (TCC) of −1.3% to 1.3% which satisfies the EIA standard specifications for X7R.