On the method of Lyapunov constant-sign functionals

© 2014 S. V. Pavlikov, A. G. Isavnin and D. T. Suyucheva. In the work there is investigated the stability of the zero solution of a nonautonomous functional differential equation of the delayed type by means of limiting equations and Lyapunov constant-sign functional. An appropriate illustrating example is given

Radiofrequency Hyperthermia of Cancer Cells Enhanced by Silicic Acid Ions Released during the Biodegradation of Porous Silicon Nanowires

The radiofrequency (RF) mild hyperthermia effect sensitized by biodegradable nanoparticles is a promising approach for therapy and diagnostics of numerous human diseases including cancer. Herein, we report the significant enhancement of local destruction of cancer cells induced by RF hyperthermia in the presence of degraded low-toxic porous silicon (PSi) nanowires (NWs). Proper selection of RF irradiation time (10 min), intensity, concentration of PSi NWs, and incubation time (24 h) decreased cell viability to 10%, which can be potentially used for cancer treatment. The incubation for 24 h is critical for degradation of PSi NWs and the formation of silicic acid ions H+ and H3SiO4- in abundance. The ions drastically change the solution conductivity in the vicinity of PSi NWs, which enhances the absorption of RF radiation and increases the hyperthermia effect. The high biodegradability and efficient photoluminescence of PSi NWs were governed by their mesoporous structure. The average size of pores was 10 nm, and the sizes of silicon nanocrystals (quantum dots) were 3-5 nm. Degradation of PSi NWs was observed as a significant decrease of optical absorbance, photoluminescence, and Raman signals of PSi NW suspensions after 24 h of incubation. Localization of PSi NWs at cell membranes revealed by confocal microscopy suggested that thermal poration of membranes could cause cell death. Thus, efficient photoluminescence in combination with RF-induced cell membrane breakdown indicates promising opportunities for theranostic applications of PSi NWs. © 2019 American Chemical Society

A new approach for producing of film structures based on Si1-xGex

In this work, we propose a new, previously unpresented in the literature, approach to the formation of Si1-xGex films. This approach includes electrochemical processes of the formation of porous silicon, electrochemical deposition of low-melting metals and Ge. Post-heat treatment is made possible to synthesize film structures based on Si1-xGex solid solutions. Using this approach an alloy of the composition Si0.4Ge0.6 has been obtained at a lower formation temperature than predicted by the phase diagram for the Si-Ge system

Raman spectra of silicon/germanium alloy thin films based on porous silicon

Regularities of composition changes of silicon/germanium alloy thin fi lms formed on a single-crystalline silicon substrate by electrochemical deposition of germanium into a porous silicon matrix with subsequent rapid thermal annealing (RTA) at temperatures of 750–950 °C are studied. An analysis of the samples by Raman spectroscopy showed that an increase of the RTA temperature leads to a decrease in the germanium concentration in the formed fi lm. A decrease of the RTA duration at a given temperature makes it possible to obtain fi lms with a higher germanium concentration and to control the composition of thin silicon/germanium alloy fi lms formed by changing the RTA temperature and duration. The obtained results on controlling the composition of silicon/germanium alloy fi lms can be used to create functional electronic devices, thermoelectric power converters, and optoelectronic devices

Роль бронхофонографии в ранней диагностике бронхиальной астмы у детей дошкольного возраста

The diagnostic significance of bronchophonography (BPG) for early detection of bronchial asthma (BA) in children from 2 to 5 years old is estimated. BPG was used to examine 210 children, including 110 children with often acute respiratory infections (ARIs), 35 children with the mild case of BA in the remission period, and 65 practically healthy children. In patients with BA compared to the group of practically healthy children, the indices of acoustic work of respiration in the high-frequency range (the so-called zone of obstructive changes) were increased, and this increase was reversible after pharmacological test with a bronchial spasmolytic. Similar changes of BPG were observed in 20% of patients with often ARIs, and two years later these children had typical clinical signs of BA. Indices of diagnostic sensitivity and specificity of BPG were equal to respectively 95.2 and 95.0%. Taking into account the relative simplicity and noninvasive character of BPG, this allows us to recommend the wide use of this method as a screening one for early diagnostics of BA in children of early and preschool age under hospital conditions.Оценена диагностическая значимость бронхофонографии (БФГ) для раннего выявления бронхиальной астмы (БА) у детей в возрасте от 2 до 7 лет. С помощью БФГ обследовано 210 детей, в том числе 110 - с частыми острыми респираторными инфекциями (ОРИ), 35 - с БА легкой степени в периоде ремиссии и 65 - практически здоровых. У пациентов с БА по сравнению с группой практически здоровых детей выявлено повышение показателей акустической работы дыхания в высокочастотном диапазоне (так называемой зоне обструктивных изменений), обратимое после проведения фармакологического теста с бронхолитиком. Аналогичные изменения БФГ были зарегистрированы у 20% пациентов с частыми ОРИ, причем у всех этих детей спустя 2 года имели место типичные клинические проявления БА. Показатели диагностической чувствительности и специфичности БФГ составили соответственно 95,2 и 95,0%, что с учетом относительной простоты выполнения и неинвазивности позволяет рекомендовать широкое применение данного метода в качестве скринингового для ранней диагностики БА у детей раннего и дошкольного возраста в амбулаторных условиях

On the method of Lyapunov constant-sign functionals

© 2014 S. V. Pavlikov, A. G. Isavnin and D. T. Suyucheva. In the work there is investigated the stability of the zero solution of a nonautonomous functional differential equation of the delayed type by means of limiting equations and Lyapunov constant-sign functional. An appropriate illustrating example is given

Implementation of flat slab column reinforced concrete frames in low cost housing construction

In research presents an analysis of flat slab column reinforced concrete frames in low cost housing construction. The features of precast flat slab column conduit within reinforced concrete frame building have been analyzed. The problems in designing flat slab column frame to improve its reliability are under consideration. Suggestions concerning the ways of improving flat slab column frame building calculations are presented. Precast flat slab column frame constructive system is promising for construction of residential and public buildings. In order to reduce the values of bending moments in the joints of columns, it is suggested to apply solid diaphragms with the functions of taking up the vertical loads in order to take up horizontal loads. It seems reasonable to define the required amount of reinforcement bars in plates by means of the kinematic limit equilibrium method

Effect of Polysaccharide Additions on the Anion-Exchange Deposition of Cobalt Ferrite Nanoparticles

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.A facile and rapid method easily reproducible in ordinary laboratory settings is proposed for preparing nanosized cobalt ferrite powders, where the precipitate used is a strongly basic anion exchange resin in the OH form. The effects caused by additions of polysaccharides having various chain natures and various molar weights on the composition, yield, and particle size of the deposition product are studied. Suggested mechanisms underlying these effects are studied. This method makes it possible to appreciably reduce the precursor annealing temperature compared to that in the state-of-art methods for preparing similar oxide systems due to the formation of highly reactive precursors. Optimal conditions are found to prepare stoichiometric precursors such that, once annealed at 600°C, would form a CoFe2O4 pure phase with particle sizes of 10–20 nm. The stability of hydrosols of the thus-prepared cobalt ferrite nanoparticles is studied by dynamic and electrophoretic light scattering. The prepared material is found to be useful for the design of magnetic core–shell hybrid nanostructures. © 2020, Pleiades Publishing, Ltd