Concept of Formation and Work of CaO Coatings in the Mode of Self-Healing

On the basis of an analysis of obtained results and literature data, we propose a kinetic model of the interaction of components in the Li[Ca]–V[O] system. The model demonstrates the cyclicity of the process. Each cycle consists of the following stages: (1) transfer of oxygen from vanadium to lithium, (2) growth of an external CaO oxide layer with simultaneous dissolution of dispersed titanium oxides in the matrix and transfer of oxygen and titanium into the solid solution, (3) penetration of the liquid metal into the solid one by the reaction-diffusion mechanism, and (4) decay of metastable triple oxide and restoration of an external CaO oxide layer. Within the framework of the model proposed, we develop the concept of work of the CaO oxide coating under isothermal conditions and in the heating–cooling mode.     

The NADPH-diaphorase activity of the bronchial epithelium in chronic lung diseases

Topochemistry and activity of NADP-H diaphorase co-localized with NO synthase was examined in operative material of lungs from patients with bronchial asthma (BA), chronic nonobstructive bronchitis (CNO) and chronic obstructive bronchitis. The enzyme activity was found to be dependent upon the types of obstruction and inflammation. In CNO the state of NO synthase was not changed. In conditions of progressive irreversible airway obstruction the enzyme activity was augmented in small bronchi epithelium and alveolar macrophages (AM). In reversible obstruction the activity of NO synthase was not changed in the epithelium but appeared high in resident cells of inflammation--AM and mast cells.     

Photonic-crystal properties of a strip domain structure with a binary magnetization distribution

A photonic crystal that is a periodic plane-layered domain structure whose magnetogyrotropic properties exhibited at microwaves are described with a tensor permeability is considered. The waveguide properties of such a crystal are investigated. The dispersion relation is obtained for a TE wave that propagates in the structure and is controlled by an external magnetic field. The dispersion relation is analyzed in the thin-layer approximation and in the case when spectrum ω(k) contains frequency and wave-number passbands and stopbands. The effect of the symmetry of the magnetization distribution over the structure’s period on the spectrum is considered.     

Do classroom ventilation rates in California elementary schools influence standardized test scores? Results from a prospective study

Limited evidence has associated lower ventilation rates (VRs) in schools with reduced student learning or achievement. We analyzed longitudinal data collected over two school years from 150 classrooms in 28 schools within three California school districts. We estimated daily classroom VRs from real‐time indoor carbon dioxide measured by web‐connected sensors. School districts provided individual‐level scores on standard tests in Math and English, and classroom‐level demographic data. Analyses assessing learning effects used two VR metrics: average VRs for 30 days prior to tests, and proportion of prior daily VRs above specified thresholds during the year. We estimated relationships between scores and VR metrics in multivariate models with generalized estimating equations. All school districts had median school‐year VRs below the California VR standard. Most models showed some positive associations of VRs with test scores; however, estimates varied in magnitude and few 95% confidence intervals excluded the null. Combined‐district models estimated statistically significant increases of 0.6 points (P = 0.01) on English tests for each 10% increase in prior 30‐day VRs. Estimated increases in Math were of similar magnitude but not statistically significant. Findings suggest potential small positive associations between classroom VRs and learning.     

Anomalously deep and fast failure of copper and bronze under the action of the corrosion products existing on them

When the corrosion products on copper and bronze are in close contact with a diluted aqueous solution of hydrochloric acid and atmospheric oxygen, they rapidly transform into effective metal (alloy) oxidizers, which provide rapid and deep metal consumption. The metal can be almost fully consumed in a reasonable technological time provided the accumulated solid phase of the products is periodically removed.     

Evolution of the structure and phase composition of MeVa-MeIVa alloys under the action of liquid lithium

We present the results of a thorough investigation of the processes occurring on the surface and inside Me_VA-Me_IVA alloys as a result of their long-term contact with liquid lithium. With V-Ti alloys as an example, we determine the role of nonmetallic impurities (O, N, C) in corrosion processes and suggest a mechanism of the formation of structure and phase composition of the investigated alloys under the action of liquid lithium. In general, the redistribution of interstitials in Me_VA-Me_IVA alloys leads to the formation of a heterogeneous structure that consists of three zones: (I) a zone where lithium interacts with a base metal, (II) a single-phase zone of a V-Ti-O (C, N) solid solution formed as a result of the dissolution of the oxide phase, and (III) a two-phase zone of internal nitriding with particles of oxynitrides of variable stoichiometry. It is also demonstrated that the directions and rates of diffusive flows of nonmetallic atoms on the melt-metal interface are controllable by rational alloying.Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 30, No. 6, pp. 58–63, November – December, 1994.