Superconducting Double Perovskite Bismuth Oxide Prepared by a Low‐Temperature Hydrothermal Reaction

Perovskite‐type structures (ABO₃) have received significant attention because of their crystallographic aspects and physical properties, but there has been no clear evidence of a superconductor with a double‐perovskite‐type structure, whose different elements occupy A and/or B sites in ordered ways. In this report, hydrothermal synthesis at 220 °C produced a new superconductor with an A‐site‐ordered double perovskite structure, (Na_0.25K_0.45)(Ba_1.00)₃(Bi_1.00)₄O₁₂, with a maximum T_c  of about 27 K.     

Valence states of 57Fe decayed from 57Mn implanted into KMnO4

In-beam Mössbauer spectra of ⁵⁷Fe, decayed from short-lived ⁵⁷Mn (T_1/2 = 1.45 min) implanted into potassium permanganate, KMnO₄, were measured at temperatures between 11 K and 130 K. This is the first application of a secondary RI beam to the study of valence states after nuclear transformation. The in-beam Mössbauer spectra obtained below 90 K could be analyzed with two components, a doublet and a singlet. From the calculations of the molecular orbital wave functions, the singlet is suggested to be substitutional ⁵⁷Fe atoms for Mn-sites in tetrahedral [MnO₄]^– with an unusually high valence state of Fe⁸⁺.     

Reactions of 57Mn implanted into solid oxygen

The in-beam Mössbauer spectroscopy using a short-lived ⁵⁷Mn (T _1/2=1.5 min) beam was carried out to study the production of the exotic chemical species of ⁵⁷Fe atoms arising from ⁵⁷Mn implanted into solid oxygen. The obtained spectra can be analyzed by four components of doublets at least, which are assigned to be novel Fe species of FeO, Fe(O₂), (O₂)FeO₂, and Fe(O₂)₂, on the basis of ab initio molecular orbital calculations.     

Z2 oscillation of mean charge states of fast Si and Cl ions after passage through thin foils

Z₂ (target atomic number) oscillation of equilibrium charge states has been observed for 30–110 MeV Si and 70 and 110 MeV Cl ions after the passage through 22 different Z₂ foils. This oscillation may be related to the Z₂ oscillation of electron capture cross sections into the projectile K vacancy.     

A Unified Approach to the Proportional Relation for Discrete-Time Single-Server Queues

It is well known that a simple relation called proportional relation holds for some queueing models, that is, the stationary queue length distribution of one system can be expressed as the product of a constant and the distribution of another system which is different only in the buffer capacity. Recently, the proportional relation has been verified for various discrete-time single-server queues with correlated arrivals, where it has been also shown that the proportional constant can be expressed in terms of the distribution of one system. This implies that the stationary queue length distribution of one system can be completely expressed in terms of the distribution of the other system. In this paper, we consider a generalized model of discrete-time single-server queue, which covers all previous ones, and give a simple and unified proof to the proportional relation as well as the expression of the proportional constant.     

Four-way-output molecular response system based on the dihydrodibenzo[c,g]phenanthrene skeleton: modulation of CD and FDCD activity by acid and electron-transfer

Presence or absence of electron-accepting dye chromophores is the key function for ON/OFF switching of fluorescence from the dihydrodibenzo[c,g]phenanthrene skeleton in 2²⁺/3. The helical fluorophore in 2²⁺ could be generated stereoselectively upon electrolysis of binaphthylic donor 1 through intramolecular chirality transmission. Huge chiroptical signals are easily detected by circular dichroism (CD) and fluorescence-detected CD (FDCD) techniques to realize novel four-way-output response.