Percolation and excitonic luminescence in SiO<Subscript>2</Subscript>/ZnO two-phase structures with a high density of quantum dots randomly distributed over a spherical surface

The results of studies of structures formed of silica (SiO₂) nanospheres and ZnO quantum dots randomly distributed over the nanosphere surface to cover an ∼0.45 fraction of the surface area are given. Because of the large surface energy of the spheres, the quantum dots formed on their surface are shaped as disks, wherein charge carriers are influenced by the quantum-confinement effect despite the large disk radii. The disk height is calculated by the effective mass method. The height is found to be comparable with the diameter of excitons in bulk ZnO. Analysis of the optical spectra shows that, at the above-indicated surface area covered with quantum dots, excitons in the array of quantum dots are above the percolation level. The use of some concepts of the percolation theory and knowledge of the topological arrangement of the samples make it possible to obtain quantitative parameters that describe this phenomenon.     

Study of thermoelastoplastic contact deformation of production tooling mixed structures

A calculation technique based on the unified methodological approach is proposed for the analysis of thermoelastoplastic contact deformation of mixed structures. The proposed numerical technique involves the finite element method. The problem of stress-strain state evaluation for one class of mixed shrouded half-hot extrusion dies is considered. Recommendations on production tooling design are given.     

High-temperature cleaning of hot industrial furnace gases by filtering elements made of porous permeable ceramics

The increasing consumption of energy in Russia increases the toxic impact of the power sector on the environment. A new technology of cleaning waste flue gases without cooling them provides not only their effective cleaning from aerosol impurities, but also recovers their substantial heat for producing electricity. It has become possible to solve these problems after the development of a highly porous permeable ceramic material and filter elements made of this material. This new material makes it possible to use hot flue gases as an alternative energy source. __________ Translated from Novye Ogneupory, No. 11, pp. 43–48, November, 2006.     

Role of cholesterol in the modulation of interdigitation in phosphatidylethanols

Phosphatidylethanol (Peth) is formed in biological membranes when ethanol replaces water in the transphosphatidylation reaction catalyzed by phospholipase D. This charged lipid accumulates in the presence of ethanol, and it has unusual properties that can influence membrane structure and function. We have previously shown that dimyristoylphosphatidylethanol (DMPeth) and dipalmitoylphosphatidylethanol (DPPeth) form the interdigitated gel phase in the presence of Tris-HCl [O.P. Bondar, E.S. Rowe, Biophys. J., 71 (1996) 1440-1449]. In the present investigation, differential scanning calorimetry (DSC) and fluorescence have been used to investigate the effect of cholesterol on the phase behavior of DPPeth and DMPeth. Our results show that cholesterol prevents the formation of the interdigitated phase in the presence of Tris-HCl, and that ethanol counters this influence and restores the ability of these lipids to interdigitate. Pyrene-PC fluorescence probe was used in this investigation and gave results that were in agreement with the conclusions based on the DSC study.     

Immediate results of surgical treatment of gastric stump cancer

An immediate result of surgical treatment of gastric stump cancer in 68 patients is presented. The resectability rate was 23.5%. Lethality after radical operations was 18.7%, after symptomatic operations and exploratory laparotomy-9.6%. Gastric resection was performed, using the method developed in the clinic with wrapping the anastomosis, or gastric stump by a loop of the afferent intestine. In development of gastric stump cancer, local spreading of a tumor is not a reason to discard performance of radical operation.     

An observation of the spin dependence of synchrotron radiation intensity

An experiment dealing with the observation of a change in the synchrotron radiation (SR) intensity during beam depolarization at the VEPP-4 storage ring is described. With a minute of measurement time, the magnitude of the effect exceeded ten statistical errors. The dependence of the sign of the effect on the sign of the magnetic field at the radiation point is demonstrated. The measured magnitude of the jump in the intensity is in agreement with the calculated spin-dependent contribution within a statistical error (equal to 7%). The suggested method is shown to be effectively applied to the observation of the transverse beam polarization in electron-positron storage rings.     

Characterization of stability of performance in patients with traumatic brain injury: Variability and consistency on reaction time tests.

The stability of performance of reaction times (RTs) on 3 visual discrimination tasks was assessed in patients with varying severity of traumatic brain injury (TBI) and in matched control Ss. Results were analyzed for group and individual variability and consistency of performance over time. There was significantly greater intersubject (group) variability in the TBI group. Individual patients (intrasubject) tended to be more variable in performance and less consistent over time than control Ss, but this occurred only with specific measures, which suggests that increased lack of stability in performance is not a general impairment after brain damage but requires specific analyses for identification of performance differences. This intrasubject variability was indepedent of test–retest and split-half test reliability. No obvious factors such as severity of brain injury were related to the variability and inconsistency of performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phase diagrams of Sc-M(IV–VII)-C systems

Translated from Poroshkovaya Metallurgiya, No. 9(321), pp. 49–57, September, 1989.     

Creep of Textile-Reinforced Composite Under Static and Cyclic Loads

Strength of Materials - The paper considers the creep of a textile-reinforced thermoplastic composite with a glass filler under the action of a combined short-term cyclic and long-term static...     

Structural Features and Tribological Properties of Multilayer Coatings Based on Refractory Metals

A comparative analysis of the structural features and tribological properties of multilayer coatings based on refractory metal compounds has been conducted in this review. Features of formation of the electronic structure of the synthesized coatings have been discussed, and the effect of methods and conditions of deposition on changes in the physicomechanical characteristics of nanocrystalline structures based on transition metal nitrides has been shown. Dependences of antifriction properties, corrosion resistance, and thermal stability on the modulation period (Λ) and the number of bilayers in the studied multilayer coatings have been determined. A decrease in the modulation period of individual layers in a coating positively affects the oxidation resistance of the coating, while an increase in the number of interfaces between the layers slows down the diffusion of oxygen atoms deep into the coating and, thereby, increases the protective properties of the multilayer system as a whole. The effect of the droplet component in cathodic-arc coatings on corrosion development mechanisms in corrosive media has been shown. A class of multifunctional multilayer coatings with an adaptive friction mechanism, which is characterized by a change in the properties and structure during tribological tests, has been discussed separately.