From the pH scale to the pO scale. The problem of the determination of the oxygen ion O2�?activity in oxide melts

This paper considers the problem of the $ {\hbox{pO}} = - \log {a_{{{\rm{O}}^{{2 - }}}}} $ scale development and standardization in comparison to the pH standard scale. The approaches describing acid–base equilibrium in oxide melts are analyzed with respect to their applicability to determine the basicity of oxide melts. Procedures for pO measurement and standardization in glass-forming melts are suggested.     

Effect of spin-orbit coupling on the structure of the electron ground state in silicon nanocrystals

The effect of spin-orbit interaction on the structure of the ground state in the conduction band of spherical silicon nanocrystals is theoretically studied using the envelope-function approximation and the k · p method. It is shown that the arising weak spin-orbit coupling of the conduction- and valence bands leads to specific asymmetric hybridization of the s- and p-type envelope functions with opposite spin orientations caused by the anisotropy of spin mixing in the silicon conduction band. As a result, the wave functions of the ground-state transform which is accompanied by an insignificant decrease in its energy. In this case, the spin-mixing parameter in nanocrystals depends strongly on their size due to the quantum-confinement effect.     

On the convergence rate of maximal deviation distribution for kernel regression estimates

Let (X, Y), X R^p, Y R¹ have the regression function r(x) = E(Y¦X = x). We consider the kernel nonparametric estimate r_n(x) of r(x) and obtain a sequence of distribution functions approximating the distribution of the maximal deviation with power rate. It is shown that the distribution of the maximal deviation tends to double exponent (which is a conventional form of such theorems) with logarithmic rate and this rate cannot be improved.     

Polyantimonic acid-based materials evaluated as moisture sensors at ambient temperature

Humidity sensors are in high demand for many applications, such as environmental monitoring and air and food quality control. Despite many inorganic and organic materials exhibit moisture sensing properties, the electrical response of many existing sensors is not stable along the time. Polyantimonic acid (PAA) is characterized by elevated proton conductivity and by high thermal stability: consequently, it is seen as promising proton conductor for usage in humidity sensing devices. In this work, for the first time, PAA-based bulk solid membranes were produced and tested as potential materials for relative humidity (RH) detection and their moisture sensitivity was evaluated. Two different amounts of binder were used for moulding the solid sensors: the ones with 10% of binder were designated as 90PAA, while the ones with 20% were named 80PAA. The structures of the solid samples were investigated by X-ray diffraction (XRD) technique, adsorption–desorption curves via Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) techniques. The electrical behaviour was examined at ambient temperature by electrical impedance spectroscopy in the entire relative humidity (RH) interval (0–100%) and in the frequency range of 40 Hz up to 60 MHz. Electrical response of the materials was correlated with the structural features of the membranes. Both 90PAA and 80PAA sensors showed total resistance 3 × 10⁵ and 3.5 × 10⁵ Ω at 10% RH, respectively. A linear decrease of the resistance on RH was observed in the range 30–90% RH for both sensors. The electrical response of the evaluated PAA-based sensors displays good repeatability and reproducibility: the ones with lower binder content showed higher moisture sensitivity as well as very good time stability over 1 year.

     

Extrema of some Gaussian processes with large trends and density estimation inL ∞ norm

Summary Let { _n (t),t [O,T _n ]} be the sequence of trends andX _n – _n (t) is a stationary Gaussian process having mean zero. This paper establishes the exact asymptotic behaviour for the probabilities , in the situation when the { _n (t)} are not asymptotically negligible and essentially contribute in the approximating distribution. The results are used to study the optimal rates of convergence for nonparametric density estimation when the closeness is measured inL norm.     

Impact of dangling bonds on the surface of silicon nanocrystals doped with shallow donors upon radiative interband transitions

It is found that the radiative recombination rate rises when silicon nanocrystals are doped with donors. This rise turns out to be stronger when a nanocrystal surface contains abundant defects capable of capturing electrons emitted by donors.     

Revisiting the Choice of a Nuclear Power Source for the Arctic

Physics of Atomic Nuclei - The possibility of creating a practically maintenance-free reactor facility with a thermoelectric generator or a Stirling engine with a capacity of 1 to 500 kWe and a...     

High temperature Ag<Superscript>+</Superscript>β”-alumina in situ sensor for sulfur-containing gases

The paper reports the development of high temperature in situ fully solid electrochemical sensor for sulfur-containing gases monitoring. The sensor is based on Ag⁺β”-Al₂O₃ membrane with Ag₂S or Ag₂SO₄ layer on its surface. Silver beta alumina was manufactured by high temperature ion exchange technique in AgNO₃ melt. The original design of the in situ sensor was developed. Three types of galvanic cells were used for the investigation of electromotive force (EMF) response on SO₂ partial pressure both in oxygen-free and oxygen-containing atmosphere in the temperature range 673–923 K. The data obtained was compared with following Nernst equations. The applicability of the sensor for in situ measurements in industrial processes is discussed.     

Temperature renormalization of the conduction electron g factor in silicon

The temperature dependence of the conduction electron g factor in silicon is studied theoretically and experimentally. The theory of renormalization of the electron energy in an external magnetic field due to interaction with lattice vibrations is developed. According to the results of the calculation, in second-order perturbation theory, the temperature renormalization of the electron g factor is determined mainly by the difference between the processes of intervalley scattering that occur with spin preservation for spin-up and spin-down electrons. Experimental investigations of n-Si samples by the electron spin resonance method demonstrated the almost linear decrease in the conduction electron g factor with an increase in the temperature in a wide range from 80 to 300 K. The results of the calculation are in good agreement with the experimental data.