Ergodic properties and thermodynamic behavior of elementary reversible cellular automata. I. Basic properties

This is the first part of a series devoted to the study of thermodynamic behavior of large dynamical systems with the use of a family of fully-discrete and conservative models named elementary reversible cellular automata (ERCAs). In this paper, basic properties such as conservation laws and phase space structure are investigated in preparation for the later studies. ERCAs are a family of one-dimensional reversible cellular automata having two Boolean variables on each site. Reflection and Boolean conjugation symmetries divide them into 88 equivalence classes. For each rule, additive conserved quantities written in a certain form are regarded as a kind of energy, if they exist. By the aid of the discreteness of the variables, every ERCA satisfies the Liouville theorem or the preservation of phase space volume. Thus, if an energy exists in the above sense, statistical mechanics of the model can formally be constructed. If a locally defined quantity is conserved, however, it prevents the realization of statistical mechanics. The existence of such a quantity is examined for each class and a number of rules which have at least one energy but no local conservation laws are selected as hopeful candidates for the realization of thermodynamic behavior. In addition, the phase space structure of ERCAs is analyzed by enumerating cycles exactly in the phase space for systems of comparatively small sizes. As a result, it is revealed that a finite ERCA is not ergodic, that is, a large number of orbits coexist on an energy surface. It is argued that this fact does not necessarily mean the failure of thermodynamic behavior on the basis of an analogy with the ergodic nature of infinite systems.     

Oxygen isotope effect of superconducting (Nd1−xCex)2CuO4−δ system

The effect of oxygen isotope substitution on the transition temperature T_c of a superconducting (Nd_1−xCe_x)₂CuO_4−δ system was studied, where the special synthetic method was taken to minimize ambiguous factors on the oxygen concentration and to guarantee the complete substitution of ¹⁶O by ¹⁸O. The isotope exponent in the relationship of T_c∝1/M was estimated to be less than 0.15 by magnetic susceptibility measurements.     

Design of a widely tunable laser with a chirped ladder filter

We theoretically investigated a digitally tunable laser with a chirped ladder filter and a ring resonator to obtain a wide wavelength tuning range covering the whole C- or L- band. The clear relation between the tuning range and laser structure, especially the ladder filter, is described analytically. The introduction of a chirped structure into a ladder filter is effective in achieving both wide tunability and a stable lasing mode. A numerical simulation based on multimode rate equations shows that a tuning range of over 40 nm and a mode suppression ratio over 40 dB can be achieved by introducing a chirped ladder filter.     

Spin structure and weak ferromagnetism of Mn3Sn

The compound Mn₃Sn shows an interesting magnetic behavior. A triangular screw spin structure has been observed below 250 K, whose period is independent of temperature. The screw structure is sensitive to heat treatment, alloy composition and impurity content.     

Important role of the 3-mercaptopropionamide moiety in glutathione: promoting effect on decomposition of the adduct of glutathione with the oxoammonium ion of TEMPO

Cyclic voltammetry of TEMPO in aqueous 0.1 M NaOH in the presence of glutathione (GSH) or cysteine (Cys) indicated the following points: (i) Both of the thiols rapidly formed adducts 3 with oxoammonium ion 1 anodically generated from TEMPO. (ii) 3 generated from GSH entered a succeeding reaction that generated N-oxide anion 2- (the reduced TEMPO). (iii) 3 produced from Cys remained intact over the time scale of voltammetry. A structural feature of GSH was considered to contribute to the observed behavior of this tripeptide. Possible structural features were evaluated by screening various thiols on the basis of whether they provided GSH-like voltammetric results. The 3-mercaptopropionamide group with an amide hydrogen in GSH was determined to be responsible for the observed difference between GSH and Cys. The likely function is to transform 3 from GSH into a 5-imino-1,2-oxathiolane intermediate, thereby releasing 2-. Product analysis for reactions of model thiols representing GSH and Cys with 1 provided support for this argument and suggested that the reaction of GSH or Cys with 1 would produce the corresponding disulfides, regardless of whether a five-membered ring intermediate was formed. The proposed function of the 3-mercaptopropionamide moiety of GSH may provide useful insight for the molecular design of exogenous thiol compounds as novel drugs for the treatment of GSH-depletion-related disorders.     

Comparisons of elemental concentrations in hair of the inhabitants of heavy metal polluted areas with those of normal Japanese

Human hair collected from the mercury, arsenic and cadmium polluted areas has been analysed by instrumental neutron activation method. The concentrations of 27 elements were compared with those of normal Japanese. Correlation coefficients of logarithmic concentrations between the elements were calculated and their significance levels were determined. Factor contribution and factor loadings of the elements were calculated for each factor by making use of principal component analysis. The factor score of each sample was also calculated for each factor to examine the effects of the contamination by heavy metals on individuals.     

A novel transformation of a 1 : 1 : 1 racemic complex of 2,2'-dihydroxy-1,1'-binaphthyl, Me4N+ Cl- and MeOH into a conglomerate in the solid state by heating or contact with MeOH vapour

The title racemate-to-conglomerate transformation which occurs in the solid state on heating or contact with MeOH vapour has been studied by IR and DTA spectral measurements, microscopic observation, and by X-ray structural and X-ray powder diffraction analysis.     

Adsorption Isotherm of Water Vapor and Its Large Hysteresis on Highly Ordered Mesoporous Silica

The first and second adsorption–desorption isotherms of water vapor on a new mesoporous material derived from kanemite have been measured. The isotherms show unusual type V isotherms and large hysteresis. The type V isotherms, which have never been observed for the other adsorbates, suggest that the mesoporous material has a hydrophobic surface, although the hydrophobicity decreased after treatment with water vapor because of rehydration of the surface. The significantly large hysteresis could be explained by the difference in contact angle between adsorption and desorption.