Pseudo-C(3)-symmetric tertiary alcohol building block via group-selective hydroalumination: a synthesis of (-)-malyngolide

The stereocontrolled preparation of tertiary alcohol 4 and its TMS surrogate 5, which share a pseudo-C(3)()-symmetry, is described. Compound 4 was used for the synthesis of (-)-malyngolide.     

Vicinal tetrahydrofuranyl substitution of alkyl chains. Tetra-, penta-, and hexafunctionalized arrays

The tetrakis (tetrahydrofuranyl) dialdehydes 14 and 19 are accessible by oxidative cleavage of extensively substituted cyclohexenes, which have in turn been assembled in a stereocontrolled manner. Reaction of 14 with an excess of the Normant reagent followed by ring closure resulted in conversion to the hexafunctionalized polyether 15. Allylindation of the same dialdehyde gave rise to lactol 16, a reactivity pattern that was essentially duplicated when 19 was treated with the Normant reagent. Attempts to add allylmagnesium bromide to 19 resulted in operation of a Tishchenko reaction with formation of lactone 23. By means of X-ray diffraction analysis, it was possible to ascertain the conformation adopted by 20 and 23 in the solid state. In addition, 15 was shown to populate a conformation in which the oxygen are very predominantly in gauche arrangements, this structural preorganization taking place in the absence of any metal ions.     

Photoelectrochemical reaction and H2 generation at zero bias optimized by carrier concentration of n-type GaN

The authors studied the photoelectrochemical properties dependent on carrier concentration of n-type GaN. The photocurrent at zero bias became the maximum value at the carrier concentration of 1.7x10(17) cm-3. Using the sample optimized carrier concentration, the authors achieved H2 gas generation at a Pt counterelectrode without extra bias for the first time. The authors also discussed the mechanism of the dependence of photocurrent on the carrier concentration of GaN.     

Fabrication of MgO barrier for a magnetic tunnel junction in as-deposited state using amorphous RE–TM alloy

MgO (1 0 0) textured films on Fe buffer layer with (1 0 0) preferential orientation were prepared by a reactive facing targets sputtering system at a substrate temperature of 100 °C during MgO deposition. This process can allow fabrication of MgO (1 0 0) tunneling barrier layer without high-temperature annealing process after the sputter-deposition. In addition, FeCo (1 0 0) preferred orientation films prepared on GdFeCo layers were improved with GdFeCo thickness. MgO films deposited on Fe (or FeCo) buffer layers revealed apparent (1 0 0) preferred orientation at the early stage of the film growth. 3 nm-thick MgO films deposited on GdFeCo [100 nm]/Fe [3 nm] exhibited (1 0 0) texture. Magnetic characteristic of perpendicular-magnetic tunnel junction (P-MTJ) element with the structure of GdFeCo [100 nm]/Fe [3 nm]/MgO [3 nm]/Fe [3 nm]/TbFeCo [100 nm] exhibited high squareness ratio of 0.8 and coercivity of free layer as low as 117 Oe by anomalous Hall effect, and (1 0 0) preferred orientation of 3 nm-thick MgO layer was observed by an X-ray diffractometer.     

Application of ToF-SIMS to the study on heartwood formation in Cryptomeria japonica trees

Influence of gold- and carbon-coating on ToF-SIMS analysis of Cryptomeria japonica (Sugi) wood has been investigated to apply the samples after observing water distribution by cryo-scanning electron microscopy (cryo-SEM) or analyzing distribution of metal elements by SEM with energy dispersive X-ray spectrometer (SEM/EDX) to ToF-SIMS analysis to study the mechanism of heartwood formation of woody plants. The intensities of peaks at the m/z 285 ion in positive mode and the m/z 283 ion in negative mode from gold- and carbon-coated samples were compared with from those of non-coated samples. Those peaks were apparently attributable to ferruginol, a typical heartwood compounds in Sugi tree. From both gold- and non-coated samples, positive m/z 285 ions were generated. On the other hand, in negative mode, the intensity of m/z 283 ion was decreased after coating with gold. From carbon-coated samples, intensities of both positive m/z 285 ion and negative m/z 283 ion were decreased. These results suggest that the samples coated with gold for cryo-SEM could be applied to ToF-SIMS analysis directly to investigate the relation between water distribution and distribution of heartwood substances in heartwood-forming Sugi trees. However, non-coated samples should be used for SEM/EDX before analyzing by ToF-SIMS.     

Development of organic light‐emitting diodes for electro‐optical integrated devices

Organic light‐emitting diodes (OLEDs) are discussed for electro‐optical integrated devices that are used for optical signal transmission. Organic optical devices including polymeric optical fibers are used for optical communication applications to realize polymeric electro‐optical integrated devices. The OLEDs were fabricated by vacuum process, i.e. the organic molecular beam deposition (OMBD) technique or a solution process on a polymeric or a glass substrate, for comparison. Optical signals faster than 100 MHz have been created by applying pulsed voltage directly to the OLED utilizing rubrene doped in 8‐hydoxyquinolinum aluminum (Alq₃), as an emissive layer. OLEDs fabricated by solution process utilizing rubrene doped in carrier‐transporting materials have also discussed. OLEDs utilizing polymeric materials by solution process are also fabricated and discussed. Moving‐picture signals are transmitted utilizing both vacuum‐ and solution‐processed OLEDs, respectively.