α-Ethynylation reaction of ketones using catalytic amounts of trialkylgallium base

Trialkylgalliums serve as a base to generate enolates from ketones. In the presence of catalytic amounts of a trialkylgallium (20-40 mol %) and 2,6-di(t-butyl)-4-methylpyridine (30-50 mol %), acyclic, and cyclic ketones were ethynylated at the α-carbon with chlorosilylethyne. The selective monoethynylation and diethynylation could be conducted for cyclic ketones by appropriate choices of the conditions, in which the addition of a catalytic amount of butyllithium (20-40 mol %) increased the yield.     

Measurements of atmospheric antiprotons

We measured atmospheric antiproton spectra in the energy range 0.2 to 3.4 GeV, at sea level and at balloon altitude in the atmospheric depth range 4.5 to 26 g/cm². The observed energy spectra, including our previous measurements at mountain altitude, were compared with estimated spectra calculated on various assumptions regarding the energy distribution of antiprotons that interacted with air nuclei.     

Synthetic Vector Analysis

Classical vector analysis is rife with geometric and physical ideas, but appears precarious from a modern viewpoint of pure mathematics. Modern vector analysis with differential forms is surely up to the contemporary standard of mathematical rigor, but geometric ideas are completely lost in the bulk of dull calculations. The main goal in this paper is to show that synthetic differential geometry, which has replenished differential geometry with nilpotent infinitesimals, can mathematically sanitize classical vector analysis by eradicating its total confusion between approximate calculations and infinitesimal calculations, thereby helping it retrieve mathematical rigor.     

Phosphorescence and photochemical properties of benzophenone included within alkali metal cation-exchanged ZSM-5 zeolites

The phosphorescence properties of benzophenone included within alkali metal cationexchanged ZSM-5 zeolites were investigated to clarify the effects of the micro-environment of hostadsorbents on the electronic excited states of guest-molecules included within the restricted void spaces. Benzophenone included within such cation-exchanged ZSM-5 zeolites was found to exist in both a protonated and hydrogen-bonded form. It was found that exchanging the cations dramatically affects the ratio of their contents. Photolysis of these systems revealed that both benzhydrol and benzpinacol were the main products, their yields strongly depending on the kind of the cations exchanged. Especially, the protonated species was found to play a significant role in the photoreactions observed with benzophenone included within zeolite cavities.     

A theory of tunnel magnetoresistance through a magnetic grain boundary

We study tunnel magnetoresistance (TMR) through grain boundaries where tunneling electrons interact with localized spins via ferromagnetic exchange interaction. It is shown that spin–flip tunneling due to the exchange interaction gives rise to appreciable effects on TMR, and that TMR increases almost linearly with increasing magnetic field.     

In-bulk and surface structuring of sapphire by femtosecond pulses

The actual space-time dependent intensity distribution of a tightly focused (numerical aperture NA = 1.35) Gaussian femtosecond pulse is modeled inside dielectric material. Such focusing is typically used for recording with sub-wavelength resolution inside dielectrics. The multi-pulse structuring inside the bulk and on the surface of sapphire are demonstrated. Formation of nano-cracks and nano-crystals is revealed inside the crystalline sapphire. Ripple formation on the surface is discussed in terms of the efficacy map calculated by theory given in ref. [J.E. Sipe, J.F. Young, J.S. Preston, H.M. van Driel, Laser-induced periodic surface structure. I. Theory, Phys. Rev. B 27 (2) (1983) 1141-1154.].     

Kinetic Studies Prove High Catalytic Activity of a Diene–Rhodium Complex in 1,4‐Addition of Phenylboronic Acid to α,β‐Unsaturated Ketones

In the 1,4‐addition of phenylboronic acid to α,β‐unsaturated ketones, [Rh(OH)(cod)]₂ has a much higher catalytic activity than [Rh(OH)(binap)]₂ (cod=1,5‐cyclooctadiene, binap=2,2′‐bis(diphenylphosphanyl)‐1,1′‐binaphthyl). Kinetic studies revealed that the rate‐determining transmetalation step in the catalytic cycle has a large rate constant when [Rh(OH)(cod)]₂ is used.     

First observation of isomeric transition from <Superscript>148<Emphasis Type="Italic">m</Emphasis></Superscript>Pr and parity assignment for excited levels in <Superscript>148</Superscript>Pr

Internal conversion electrons from the decay of ¹⁴⁸Ce and ^148mPr have been measured with a Si(Li) detector. The radioactive sources were produced by the thermal neutron-induced fission of ²³⁵U, followed by an on-line mass separation. K- and L-conversion electrons of the isomeric transition from ^148mPr were newly observed at 34.6 and 70.8 keV, respectively. The M3 multipolarity was assigned to this transition from the experimental conversion coefficients, and, consequently, the 76.8 keV isomeric level was found to be a 4^- state. Parities of some excited levels in ¹⁴⁸Pr were also deduced.