Effect of Prefiring Condition on the In-Plane Orientation of Epitaxial Oxide Films in Coating-Pyrolysis Process

Epitaxial -Fe₂O₃ films were obtained by using iron 2-ethylhexanoate as a starting material. A coating solution was spun on -Al₂O₃ single-crystal substrates, and prefiring and final heat-treatment at various temperatures in air or low oxygen partial pressure were carried out. The degree of in-plane orientation was estimated in terms of full width at half maximum of X-ray diffraction (XRD) -scans. The results of TG-DTA, IR, and XRD suggested that the optimum prefiring condition for obtaining highly epitaxial films is in the range 200–300°C which corresponds to removal of most of the organic component from the precursor, prior to crystallite formation of metal oxide. When the films were prefired at higher temperatures, different atmospheres in prefiring and final heat-treatment lowered the in-plane orientation of the films.     

Rhodium-catalyzed substitution reaction of aryl fluorides with disulfides: p-orientation in the polyarylthiolation of polyfluorobenzenes

In the presence of a catalytic amount of RhH(PPh3)4 and 1,2-bis(diphenylphosphino)benzene, an aromatic fluoride, an organic disulfide (0.5 equiv), and triphenylphosphine (0.5 equiv) reacted in refluxing chlorobenzene to give an aryl sulfide in high yield. Since triphenylphosphine trapped fluoride atoms forming phosphine difluoride, both organothio groups of the disulfide reacted effectively, and the fluoride substituent reacted more readily than the chloride and bromide. The reaction of hexafluorobenzene and a diaryl disulfide gave 1,4-diarylthio-2,3,5,6-tetrafluorobenzene, 1,2,4,5-tetraarylthio-3,6-difluorobenzene, and hexaarylthiobenzene in a stepwise manner; pentafluorobenzene gave 1-arylthio-2,3,5,6-tetrafluorobenzene; 1,2,3,4-tetrafluorobenzene gave 1,2-diarylthio-3,6-difluorobenzene; and 1,2,4,5-tetrafluorobenzene gave 1,4-diarylthio-2-5-difluorobenzene. The polyarylthiolation reaction of polyfluorobenzenes exhibited a strong tendency to form 1,4-difluorobenzenes.     

Absolute stereochemistry of amphidinolide Q

The absolute configurations at five chiral centers in amphidinolide Q (1), a cytotoxic 12-membered macrolide isolated from a marine dinoflagellate Amphidinium sp., were elucidated to be 4R, 7R, 9S, 11R, and 13R on the basis of NMR analyses and a modified Mosher's method.     

Electrostatic Maxwell stress model of the shapes of condensed phase domains in monolayers at the air-water interface

The formation mechanism of the shapes of condensed phase domains in monolayers at the air-water interface was investigated taking into account the surface pressure, line tension, and electrostatic energy due to the spontaneous polarization generated in normal and in-plane direction. By deriving the shape equation of monolayer domains as the mechanical balance at the domain boundary, we found that the electrostatic energy contributes to the shape equation as electrostatic Maxwell stress. Development of a cusp from condensed phase domains of fatty acid monolayers, which has been experimentally observed, was analyzed by the shape equation. It was found that the development of a cusp originated from the strong Maxwell stress, which was induced by the non-uniform orientational distribution in the fatty acid domain, and that cusped shapes gave a minimum of the free energy of the domain. It demonstrates that the shape equation with Maxwell stress, which is derived in the present study, is useful to study the formation mechanism of the shapes of condensed phase domains in monolayers.     

Nagelamides M and N, new bromopyrrole alkaloids from sponge Agelas species

Two new bromopyrrole alkaloids, nagelamides M (1) and N (2), have been isolated from an Okinawan marine sponge Agelas species, and the structures and stereochemistry were elucidated from the spectroscopic data. Nagelamide M (1) is a novel bromopyrrole alkaloid possessing a 2-amino-octahydropyrrolo[2,3-d]imidazole ring with a taurine unit, while nagelamide N (2) is a new bromopyrrole alkaloid possessing a 2-amino-tetrahydroimidazole-4-one ring with a taurine unit and 3-(dibromopyrrole-2-carboxamido)propanoic acid moiety. Nagelamides M (1) and N (2) exhibited antimicrobial activity.     

An Aqueous Redox Flow Battery Using CO2 as an Active Material with a Homogeneous Ir Catalyst**

For the application of CO₂ as an energy storage material, a H₂ storage system has been proposed based on the interconversion of CO₂ and formic acid (or formate). However, energy losses are inevitable in the conversion of electrical energy to H₂ as chemical energy (≈70 % electrical efficiency) and H₂ to electrical energy (≈40 % electrical efficiency). To overcome these significant energy losses, we developed a system based on the interconversion of CO₂ and formate for the direct storage and generation of electricity. In this paper, we report an aqueous redox flow battery system using homogeneous Ir catalysts with CO₂-formate redox pair. The system exhibited a maximum discharge capacity of 10.5 mAh (1.5 Ah L⁻¹), capacity decay of 0.2 % per cycle, and total turnover number of 2550 after 50 cycles. During charging-discharging, in situ fluorescence X-ray absorption fine structure spectroscopy based on an online setup indicated that the active species was in a high valence state of Ir^IV.     

Structural Determination and Chemical Synthesis of the N-Glycan from the Hyperthermophilic Archaeon Thermococcus kodakarensis

Asparagine-linked protein glycosylations (N-glycosylations) are one of the most abundant post-translational modifications and are essential for various biological phenomena. Herein, we describe the isolation, structural determination, and chemical synthesis of the N-glycan from the hyperthermophilic archaeon Thermococcus kodakarensis. The N-glycan from the organism possesses a unique structure including myo-inositol, which has not been found in previously characterized N-glycans. In this structure, myo-inositol is highly glycosylated and linked with a disaccharide unit through a phosphodiester. The straightforward synthesis of this glycan was accomplished through diastereoselective phosphorylation and phosphodiester construction by S_N2 coupling. Considering the early divergence of hyperthermophilic organisms in evolution, this study can be expected to open the door to approaching the primitive function of glycan modification at the molecular level.     

Total Synthesis of 6-Deoxydihydrokalafungin,a Key Biosynthetic Precursor of Actinorhodin,and Its Epimer

In this article, we report the total synthesis of 6-deoxydihydrokalafungin (DDHK), a key biosynthetic intermediate of a dimeric benzoisochromanequinone antibiotic, actinorhodin (ACT), and its epimer, epi-DDHK. Tricyclic hemiacetal with 3-siloxyethyl group was subjected to Et₃SiH reduction to establish the 1,3-cis stereochemistry in the benzoisochromane, and a subsequent oxidation/deprotection sequence then afforded epi-DDHK. A bicyclic acetal was subjected to AlH₃ reduction to deliver the desired 1,3-trans isomer in an approximately 3:1 ratio, which was subjected to a similar sequence to that used for the 1,3-cis isomer that successfully afforded DDHK. A semisynthetic approach from (S)-DNPA, an isolable biosynthetic precursor of ACT, was also examined to afford DDHK and its epimer, which are identical to the synthetic products.     

Future atmospheric neutrino data from Super-Kamiokande

Expected sensitivity of future atmospheric neutrino data from Super-Kamiokande on neutrino oscillation physics is discussed. We expect that the accuracy of the sin ²θ₂₃ measurement will be improved with (exposure time) . By analyzing high energy fully contained events, it could be possible to statistically demonstrate the existence of charged current ν_τ interactions at the 3 standard deviation level with a few more years of data. Subdominant ν_μ → ν_e oscillations could be observed if θ₁₃ is near the present limit. However, significantly more data will be required to observe a 3 standard deviation effect.