How many miles to βX? II — Approximations to βX versus cofinal types of sets of metrics

Kada, Tomoyasu and Yoshinobu proved that the Stone-?ech compactification of a locally compact separable metrizable space is approximated by the collection of d-many Smirnov compactifications, where d is the dominating number. By refining the proof of this result, we will show that the collection of compatible metrics on a locally compact separable metrizable space has the same cofinal type, in the sense of Tukey relation, as the set of functions from ω to ω with respect to eventually dominating order.     

Spontaneous ignition of ultra-fine magnesium powder without an original oxide coat at room temperature in O2/N2 mixture streams

To examine the pyrophoric characteristics of Mg powder, we generated ultra-fine Mg particles (average particle diameter: about 0.3 μm) without an original oxide coat in an Ar stream. The ignition of the powder was measured by using the impinging O₂/N₂ mixture streams over a wide range of the experimental parameters: pressure, oxygen concentration and velocity of the streams. The Mg powder was found to ignite even at room temperature. The spontaneous ignition temperatures in the range of 278  324 K were insensitive to all the experimental parameters. The ignition delay time had a tendency to decrease with increasing experimental parameters.The ignition process of the Mg powder was found to be controlled by the surface reaction rate without an oxide coat. We proposed a new ignition hypothesis considering a critical oxide thickness on the Mg powder particles at the transition temperature from protective to non-protective nature: that is, the ignition of the Mg powder occurs when the powder temperature rises above the transition temperature before surface reactions form a protective oxide coat with the critical thickness on the individual particle surfaces. According to this hypothesis, an ignition model of Mg powder cluster was developed, and the relation between the spontaneous critical ignition temperature and the ultra-fine powder size, depending on the critical thickness of the protective oxide coat, was clarified. The critical oxide thickness was estimated.     

Ab initio calculations of transport properties of atomic bridges by the recursion-transfer-matrix method

We present an efficient self-consistent method for approaching quantum transport through atomic-scale structures. Using the recursion-transfer-matrix (RTM) method with a separable form of nonlocal pseudopotentials, scattering waves propagating between metallic electrodes through nano-bridged structures are efficiently calculated on the basis of the density-functional formalism. We performed calculations with this method of the conductance of Al atomic wires with various kinds of single atoms mixed at the contact to one electrode. We found that the transport properties are considerably affected by the bonding nature of the atom at the contact. The conductance is largely determined by the atomic species at the contact and does not change much as the length of the atomic wire increases.     

Immobilization of microbial cells by radiation-induced polymerization of glass-forming monomers and immobilization ofStreptomyces phaeochromogenes cells by polymerization of various hydrophobic monomers

The immobilization ofStreptomyces phaeochromogenes cells was studied by the radiation-induced polymerization of various hydrophobic glass-forming monomers at low temperatures. The glucose isomerase activity of cells immobilized in hydrophobic polymers showed no decrease in activity with repeated use (batch enzyme reaction). Activity increased with increasing monomer concentration in contrast to results with the immobilized enzyme. The hydrophobic polymer composite was microspheric in form. The particle diameter of the composite increased with the increasing monomer concentration.K _m values of the immobilized cells were close to that of intact cells. It was deduced that the cells were trapped on the surface part of the hydrophobic polymer ready to react with the substrate, and not within the matrix where diffusion would play an important role in reaction rates.     

Molecular vibrations and force fields of alkyl sulfides: Part XV. C-S stretching vibrations of aliphatic alkyl sulfides

The C-S stretching vibrations of 28 aliphatic sulfides including one thiol are summarized, and all of the C-S stretching bands are classified into several groups. An extraordinarily low frequency associated with the ethyl group is discussed briefly.     

Insights into sticking of radicals on surfaces for smart plasma nano-processing

In reactive plasma processing, species produced in the plasma reach the surface of a substrate and cause etching, deposition and surface modification through surface reactions. These reactions are characterized by the densities and energies of species incident on the surfaces. In order to realize nano-scale plasma processing, important species for plasma processing have been identified and characterized, and their behavior, not only in the gas phase, but also on the surface, have been clarified and controlled. One of the most critical parameters for insights into surface reaction kinetics of radicals is sticking and surface loss probability. On the basis of radical densities measured by various methods, the sticking and surface reaction loss probabilities have been compiled, and they enable the quantitative understanding of the kinetics of radicals on the surface in the plasma. In this article, the sticking and surface reaction loss probabilities measured thus far are reviewed focusing on fluorocarbon gas, silane gas and methane gas based plasma processes. The establishment of a smart plasma process and the development of an autonomous production device with control of radicals on the basis of insights into the surface reactions for nano-scale plasma processing are presented.     

Application of MCD spectroscopy and TD-DFT to nonplanar core-modified tetrabenzoporphyrins: effect of reduced symmetry on nonplanar porphyrinoids

The optical spectra of a series of core-modified tetrabenzoporphyrins were analyzed to determine the effects of core modification, ligand folding, and partial benzo substitution at the ligand periphery on the electronic structure by using magnetic circular dichroism (MCD) and NMR spectroscopy, X-ray crystallography, cyclic and differential pulse voltammetry, and TD-DFT calculations. Planar 21-carba-, 21-thia-, 21,23-dithia-, and 21-oxa-23-thiatetrabenzo[b,g,l,q]porphyrins reported previously were studied together with the previously unreported 21-oxa- and 21-carba-23-thiatetrabenzo[b,g,l,q]porphyrins. The optical properties of these compounds are compared to those of tetrabenzo[b,g,l,q]-, 5,10,15,20-tetraphenyl-, 5,10,15,20-tetraphenyltetrabenzo[b,g,l,q]-21-thia-, 5,10,15,20-tetraphenyltetrabenzodithia-, 5,10,15,20-tetraphenyldibenzo[g,q]-21,23-dithia-, 5,10,15,20-tetraphenyldibenzo[b,l]-21,23-dithia-, 5,10,15,20-tetraphenyltribenzo[g,q,l]-21-thia-, and 5,10,15,20-tetraphenylbenzo[b]-21-thiaporphyrins. Michl's perimeter model and Gouterman's four-orbital model are used to conceptualize the results and to account for red shifts commonly observed in the spectral bands of nonplanar porphyrinoids.