Visualization of the tidal flow in Sasebo and Oomura Bays

Sasebo and Oomura Bays situated in the northwest of Kyushu, Japan form a coupled bay linked by a channel. The tidal flow in and between these bays is visualized by the satellite images and the dispersion of Lagrangian particles is numerically studied. The satellite images are available to visualize the tidal flow at the mouth of Hario-seto from the maximum flood tide to the end of ebb tide at Tainoura. The seawater plume from the mouth of Hario-seto goes southeastward and then rotates anti-clockwise. The time of one rotation is about 6 to 7 periods. The plume extends about 10 km from the mouth of Hario-seto. Lagrangian particles in Sasebo Bay also flow into Oomura Bay through Haiki-seto.     

Potassium-selective membrane electrodes based on macrocyclic metacyclophanes analogous to calixarenes.

The tetrabutyl ester derived from 9,16,25,32-tetrahydroxy[3.1.3.1]metacyclophane was an excellent ionophore for constructing a K+-selective membrane electrode. This ionophore exhibited a much higher selectivity toward K+ than the structurally similar potassium ionophore IV commercially available from Fluka. In particular, the interference from organic ammonium ions decreased remarkably. Potassium ionophore IV possessed oxygen atoms in the ring structure, while the present ionophore changed the oxygen atoms to carbon atoms. Thus, the removal of oxygen atoms in ring constituents of the metacyclophane acted to reduce the interaction with the NH3+ group of organic ammonium ions. The size of the cavity of the present ionophore was between those of calix[4]arene and calix[6]arene derivatives, which act as Na+ and Cs+ ionophores, respectively, demonstrating that the ability to recognize alkali metal cations was strongly cavity size-dependent. The present K+-selective electrode had less interference from Rb+ and Cs+ than an electrode constructed using valinomycin, but suffered greater interference from Na+.     

Resolution of amino acids on optically active stationary phase by gasChromatography

Summary The various enantiomeric esters of TFA--amino acid may be separated directly by gas chromatography on optically active stationary phase. In this work we investigated the resolution of relatively volatile amino acids (alanine, -amino-n-butyric acid, valine, threonine, allo-isoleucine, isoleucine, norvaline, leucine, proline, norleucine, serine) and less volatile amino acids (cysteine, aspartic acid, methionine, phenylalanine, glutamic acid) on a glass capillary column coated with N-caproyl-L-valyl-L-valine cyclohexyl ester.     

Σ hypernuclear spectra from (K, π) inclusive reactions

We report on DWIA calculations of the pion inclusive spectra related to Σ-formation in (K⁻, π⁺) reactions on nuclei. Realistic distorted waves are used to describe the incoming kaon and outgoing pion. The Σ wave function is calculated in a real Woods-Saxon potential, the depth of which provides information about the underlying Σ N effective interaction. The absorptive effect due to the Σ-Λ conversion process in the nuclear medium is taken into account by effective two-channel coupled equations. Comparisons are made with the available data on ¹²C and ¹⁶O. Using a weak Σ-nucleus potential the overall agreement is satisfactory for the spectrum derived from kaon-in-flight experiments. Concerning the three peaks reported in a stopped kaon experiment on ¹²C, the lowest peak structure can be generated by increasing the depth of the Σ potential in ¹²C. However, the remaining two narrow structures cannot be reproduced as Σ-particle-proton-hole states in our continuum treatment of the Σ spectrum. The difficulties in extracting the strength of the Σ-nucleus spin-orbit potential are also discussed.     

Total Synthesis of Siomycin A: Construction of Synthetic Segments

The five practical segments for the total synthesis of siomycin A, that is, the dehydropiperidine segment A ( 5 ), the pentapeptide segment B ( 3 ), the dihydroquinoline segment C ( 6 ), and the β‐phenylselenoalanine dipeptide segments D ( 7 ) and E ( 4 ), were synthesized. Segment A ( 5 ) was constructed by the coupling of the azomethine ylide and the chiral sulfinimine, followed by the stereoselective reduction of the six‐membered imine function. Segment B ( 3 ) was synthesized by the phenylselenylation of the β‐lactone, stereoselective vinylzinc addition to the chiral sulfinimine, and oxazoline–thioamide conversion. Segment C ( 6 ) was prepared by the one‐pot olefination of the tetrahydroquinoline N‐oxide using triflic anhydride and triethylamine, stereoselective reduction of the methyl ketone function, and regioselective Yb(OTf)₃‐catalyzed epoxide opening by the amino group. Segments D ( 7 ) and E ( 4 ) were synthesized by coupling of the properly protected β‐phenylselenoalanines.     

Total Synthesis of Siomycin A: Completion of the Total Synthesis

The total synthesis of siomycin A ( 1 ), a representative compound of the thiostrepton family of peptide antibiotics, was achieved by incorporating the five synthetic segments A ( 2 ), B ( 3 ), C ( 4 ), D ( 5 ), and E ( 6 ). The dehydropiperidine segment A ( 2 ) was esterified with the dihydroquinoline segment C ( 4 ), and the subsequent coupling with the β‐phenylselenoalanine dipeptide segment D ( 5 ) at the segment C portion followed by lactamization between the segments A and D gave segment A‐C‐D ( 27 ). This was amidated with the pentapeptide segment B ( 3 ) at the segment A portion followed by one‐pot cyclization (between segments A and B) and elongation (with the β‐phenylselenoalanine dipeptide segment E ( 6 ) at the segment A portion), thus furnishing siomycin A ( 1 ).     

Dual stimuli-responsive phase transition of an ionic liquid/water mixture

A mixture of tetrabutylphosphonium N-trifluoromethanesulfonyl leucine and water showed a reversible change between a homogeneous phase and separated liquid-liquid phase by bubbling CO(2) gas or N(2) gas at atmospheric pressure as well as a small temperature change.     

Promotion effects of optical antipodes on the formation of helical fibrils: chiral perfluorinated gelators

A chiral gelator, RR- or SS-N,N'-diperfluorooctanoyl-1,2-diaminocyclohexane, gelated racemic 2-butanol. The gel was most stable at the racemic mixture, its stability lowered with the increase in the optical purity of the gelator. Notably, characteristic helically coiled fibrils were formed in the narrow region of enantiomer excess (ee = 0.2-0.4). Promotion effects of the antipodal enantiomers are proposed.     

Mott transition in the two-dimensional Hubbard model

Spectral properties of the two-dimensional Hubbard model near the Mott transition are investigated by using cluster perturbation theory. The Mott transition is characterized by freezing of the charge degrees of freedom in a single-particle excitation that leads continuously to the magnetic excitation of the Mott insulator. Various anomalous spectral features observed in cuprate high-temperature superconductors are explained in a unified manner as properties near the Mott transition.     

Generation and size classification of single-walled carbon nanotube aerosol using atmospheric pressure pulsed laser ablation (AP-PLA)

Gas suspended single-walled carbon nanotubes (SWCNTs) with single tube diameter smaller than 2 nm and length of longer than 500 nm were generated by simple and continuous system using laser ablation technique under atmospheric conditions. Graphite target containing 0.5 wt%-nickel and 0.5 wt%-cobalt was ablated by Nd:YAG laser in an electrical furnace under atmospheric pressure of nitrogen flow that allowed one step and continuous synthesis of the SWCNTs. Size distribution of the gas suspended SWCNTs aerosol was measured using size-classification by a differential mobility analyzer (DMA) coupled with a condensation particle counter (CPC) used as a detector. Characteristics of SWCNT aerosol generated under the different temperature were also investigated using scanning and transmission electron microscopes and Raman scattering. Mono-mobility SWCNT aerosol with mobility diameter of 100 and 200 nm was successfully prepared after the size separation using a DMA.