Beam deceleration for block-face scanning electron microscopy of embedded biological tissue

The beam deceleration (BD) method for scanning electron microscopes (SEM) also referred to as "retarding" was applied to back-scattered electron (BSE) imaging of the flat block face of a resin embedded biological specimen under low accelerating voltage and low beam current conditions. BSE imaging was performed with 0-4 kV of BD on en bloc stained rat hepatocyte. BD drastically enhanced the compositional contrast of the specimen and also improved the resolution at low landing energy levels (1.5-3 keV) and a low beam current (10 pA). These effects also functioned in long working distance observation, however, stage tilting caused uncorrectable astigmatism in BD observation. Stage tilting is mechanically required for a FIB/SEM, so we designed a novel specimen holder to minimize the unfavorable tilting effect. The FIB/SEM 3D reconstruction using the new holder showed a reasonable contrast and resolution high enough to analyze individual cell organelles and also the mitochondrial cristae structures (~5 nm) of the hepatocyte. These results indicate the advantages of BD for block face imaging of biological materials such as cells and tissues under low-voltage and low beam current conditions.     

Microlocal smoothing effect for the Schrödinger evolution equation in a Gevrey class

We discuss the microlocal Gevrey smoothing effect for the Schrödinger equation with variable coefficients via the propagation property of the wave front set of homogenous type. We apply the microlocal exponential estimates in a Gevrey case to prove our result.     

Gravitational baryogenesis

We show that a gravitational interaction between the derivative of the Ricci scalar curvature and the baryon-number current dynamically breaks CPT in an expanding Universe and, combined with baryon-number-violating interactions, can drive the Universe towards an equilibrium baryon asymmetry that is observationally acceptable.     

Asymmetric synthesis via chiral silicon reagents. Chiral α-hydroxyalkyl anion equivalents from vinylsilanes containing optically active amino or alkoxy groups on silicon

Chiral vinylsilanes containing optically active functional groups on silicon have been used as precursors for chiral α-hydroxyalkyl anion equivalents via a sequence of addition of η-butyllithium, coupling with organic halides, and oxidative cleavage of the silicon-carbon bond, to give optically active alcohols of up to 60% ee.     

A new flavone C-glycoside from the style of Zea mays L. with glycation inhibitory activity

A new flavone C-glycoside, chrysoeriol 6-C-beta-fucopyranoside (1), and a known flavone C-glycoside (2) were isolated from the style of Zea mays L. These structures were elucidated on the basis of spectroscopic analysis. Compound 1 exhibited glycation inhibitory activity.     

Metal catalyzed cross-coupling reactions of carbanions α to silafunctional groups. New α-hydroxyalkyl anion equivalents

Carbanions α to (alkoxy)silyl or (amino)silyl groups act as nucleophilic α-hydroxy-alkylating agents for organic halides and epoxides via the metal catalyzed coupling reaction and the subsequent oxidative cleavage of the carbon-silicon bond.     

Synthesis and molecular characterization of A-B-A type block copolymer consisting of poly(γ-benzyl l-glutamate) as the a component and polyisoprene as the B component

A-B-A type block copolymers (GIG) composed of poly(γ-bezyl l-glutamate) (PBLG) as the A component and polyisoprene (PI) as the B component were prepared. The method of synthesis consists of the polymerization of the γ-benzyl l-glutamate N-carboxy anhydride initiated by the amine groups capped at both ends of the PI block which has a moderate degree of polymerization. When dissolved in a helicogenic solvent, such as N,N′-dimethylformamide (DMF) or ethylene dichloride (EDC), the GIG is expected to take a conformation which may be pictured as two rigid blocks linked by a flexible joint, since the PI block portion is intolerant of intrachain hydrogen bonding. Hence, the GIG block copolymers would be considered as a macromolecular model of a once-broken rod with equal rod sections, if the molecular weight of the PBLG portion was relatively much higher than that of the PI portion. After molecular characterization on GIG by the circular dichroism measurement, the viscosity behavior in a helicogenic solvent was determined, and the result was compared with the corresponding data on PBLG, which assumes the form of a straight rod in a helicogenic solvent. It was found that the value of [η] of GIG block copolymers was about 5/8 of those of PBLG of the equal molecular weight. This finding is in good agreement with the theoretical prediction.     

Chemical constituents of the style of Zea mays L. with glycation inhibitory activity

A new sesquiterpene along with 15 known compounds were isolated from the style of Zea mays L. These structures were elucidated on the basis of spectroscopic analysis. The ability of these compounds to inhibit glycation in vitro was analyzed. This allowed determination of chemical functional groups required for the inhibition of glycation.