New sesquiterpenoid from the New Zealand liverwort Lepidozia spinosissima

A new cyclogorgonane-type sesquiterpenoid, 1,5-cyclo-3,6-gorgonadien-15,11-olide was isolated from the New Zealand liverwort Lepidozia spinosissima, together with three known sesquiterpenoids. Their structures were established by the extensive NMR techniques and chemical reaction.     

Multiplex amplified product-length polymorphism analysis for rapid detection of human mitochondrial DNA variations.

A number of mutations in coding and noncoding regions of mitochondrial DNA (mtDNA) have previously been studied. In the present study, we simultaneously typed six mutation sites in the coding region by use of amplified product-length polymorphism (APLP) analysis. The mtDNA variations of 2471 individuals from 20 populations of Japanese, Korean, Chinese, and German were examined and classified into 18 haplotypes. Two of these haplotypes, B1 (estimated ancestral haplotype) and C1, were distributed among all populations tested. However, the haplotypes A1, A2, B2, B3, and C2 were mostly restricted to the Mongoloid populations, whereas haplotypes B5 and C5 appeared almost exclusively in the German population. Phylogenetic analysis by the neighbor-joining method revealed that the Japanese populations were more closely related to each other than to the other East Asian populations surveyed. The multiplex APLP method is suitable for large-scale screening studies of mtDNA variability because it is both rapid and economical.     

Direct beta-alkylation of secondary alcohols with primary alcohols catalyzed by a CpIr complex

A new catalytic system for beta-alkylation of secondary alcohols has been developed. In the presence of [CpIrCl(2)](2) (Cp = pentamethylcyclopentadienyl) catalyst and base, the reactions of various secondary alcohols with primary alcohols give beta-alkylated higher alcohols in good to excellent yields without any hydrogen acceptor or hydrogen donor. This reaction proceeds via successive hydrogen-transfer reactions and aldol condensation. [reaction: see text]     

Measurement of the electrophoretic mobility of sheep erythrocytes using microcapillary chips

Cell electrophoretic mobility (EPM) can be used to characterize individual cells. The purpose of this study is to establish reproducible and reliable cell EPM values obtained using microcapillary electrophoresis (microCE) chips. We studied cell electrophoresis on microCE chips through the comprehensive measurement of EPM and zeta potential. The inner wall of microchannels in microCE chips was coated with three kinds of reagents, namely bovine serum albumin (BSA), gelatin, and 2-methacryloyloxyethylphosphorylcholine (MPC) polymer to prevent nonspecific adhesion and interaction between cells and the inner wall. Electrophoresis was conducted in phosphate-buffered saline (pH 4-9) using erythrocytes extracted from sheep whole blood. Electroosmotic flow (EOF) mobility was measured using noncharged particles, and then the true EPM was calculated by subtracting the EOF mobility from the electromigration. MPC polymer coatings in microCE chips reduced the zeta potential of the inner wall and fully prevented nonspecific adhesion. EPM data obtained using microCE chips were almost the same and reproducible over a wide range of pH irrespective of the coating reagent used. In conclusion, reliability in the measurement of cell EPM using microCE chips was realized.     

The virtual origin of riblets in an open channel flow

In this paper, a method using the mean velocity profiles for the buffer layer was developed for the estimation of the virtual origin over a riblets surface in an open channel flow. First, the standardized profiles of the mixing length were estimated from the velocity measurement in the inner layer, and the location of the edge of the viscous layer was obtained. Then, the virtual origins were estimated by the best match between the measured velocity profile and the equations of the velocity profile derived from the mixing length profiles. It was made clear that the virtual origin and the thickness of the viscous layer are the function of the roughness Reynolds number. The drag variation coincided well with other results.Nomenclature f _r skin friction coefficient - f _ro skin friction coefficient in smooth channel at the same flow quantity and the same energy slope - g gravity acceleration - H water depth from virtual origin to water surface - H ⁺ u*H/ - H false water depth from top of riblets to water surface - H ⁺ u*H/ - I _e streamwise energy slope - I _b bed slope - k riblet height - k ⁺ u*k/ - l mixing length - l _s standardized mixing length - Q flow quantity - Re Reynolds number volume flow/unit width/v - s riblet spacing - u mean velocity - u* friction velocity = - u* false friction velocity = - y distance from virtual origin - y distance from top of riblet - y ₀ distance from top of riblet to virtual origin - y _v distance from top of riblet to edge of viscous layer - y ⁺ u*y/ - y ⁺ u*y/ - y ₀ ⁺ u*y ₀/ - u ⁺ u*y/ - shifting coefficient for standardization - thickness of viscous layer=y ₀+y - ⁺ u*/ - ⁺ u*/ - eddy viscosity - ridge angle - v kinematic viscosity - density - shear stress     

Sputtering induced recombination of nitrogen isotopes on tungsten

Adsorbed isotopic mixtures of ¹⁴N₂ and ¹⁵N₂ at low coverages on polycrystalline tungsten have been used as model systems for studying sputtering induced recombination during secondary ion mass spectrometry (SIMS). Earlier studies have shown that N₂ is completely dissociated on a W surface at low coverage. Thermal desorption spectroscopy (TDS) has been employed here to confirm this fact; our results show that complete isotopic mixing occurs. Adsorbed nitrogen can be sputtered as both atoms and molecules and sputtering induced recombination of adsorbate atoms increases as primary ion energy increases. Sputtering induced recombination is detected through isotopic mixing in SIMS. The data show that the dominant mechanism for sputtering of dimers (N₂) is not direct emission from the surface but rather a sputtering induced recombination mechanism.     

Trajectory analysis of ions formed in the field emitter inter-electrode region

Ion trajectories are three-dimensionally analyzed to determine the main source of ions striking the emitting area of a field emitter. Computer calculations of the ion trajectories are made for a field emitter in the shape of a sphere radius 1000 Å, mounted on an orthogonal cone, and anode radii of 3 cm and 1 cm centered at the emitter. Approximately 10^?10 to 10^?9fraction of the ions formed at the anode by electron impact desorption reach the emitter tip. Only those residual gas ions generated in the space of a few μm around the tip are able to impinge on the emitting area. Under typical operating conditions of 10^?9 Torr, the residual gas ions striking the tip are 10 to 10² times greater than those from the anode, assuming an ion ejection of one ion per 10⁵ electrons, and an anode potential of about 3 kV.     

Electrochemical techniques for microfluidic applications

Electrochemical principles provide key techniques to promote the construction of bio/chemical microsystems of the next generation. There is a wealth of technology for the microfabrication of bio/chemical sensors. In addition, microfluidic transport in a network of flow channels, pH regulation, and automatic switching can be realized by electrochemical principles. Since the basic components of the devices are electrode patterns, the integration of different components is easily achieved. With these techniques, bio/chemical assays that require the exchange of solutions can be conducted on a chip. Furthermore, autonomous microanalysis systems that can carry out necessary procedures are beginning to be realized. In this article, techniques developed in our group will be comprehensively introduced.