Effect of anodizing regimes on the volume expansion factor of the oxide films

The volume expansion factor of porous alumina, formed by through anodizing of an Al foil in ox- alic and sulphuric acid has been studied. The thickness of obtained porous alumina films was measured by a mechanical profilometer with a computer signal processing. The volume expansion factor of porous alumina varied from 1.35 to 1.65. Linear dependences were obtained for the vol- ume expansion factor of porous alumina versus the anodizing voltage and the ionic current density logarithm versus the inverse volume expansion factor. Unlike oxide formation in sulphuric acid, these dependences have two subsequential rectilinear regions in oxalic acid

Features of the porous morphology of anodic alumina films at the initial stage of disordered growth

A characteristic feature of disordered porous anodic film growth at the initial stage of aluminum anodizing was revealed by varying the electrolyte type and anodizing voltage. The samples were obtained by the electrochemical oxidation of thin aluminum films (100 nm thick) on SiO2/Si substrates in a 0.3 M oxalic acid at 10–50 V and were studied by SEM. The ImageJ analysis of the images revealed the simultaneous development of two large groups of pores: major pores with a large diameter and minor pores with a smaller diameter. When anodizing in oxalic acid at 10–50 V, it has been shown that the ratio of the diameters of the major and minor pores remains constant and is about 1.17. Using a geometric model, we demonstrated that the centers of the minor pores are located inside the elementary hexagonal cell formed by the centers of the major pores. Moreover, our results are very close to the theoretical value of 2/√3. At the initial stage of disordered pore growth, the development of minor pores rather than major pores is not a random process and is determined by energy-efficient conditions for the development of pores inside the hexagonal cells formed by the major pores. The increase in compressive mechanical stress in the anodic film leads to an interruption in the development of such pores

Investigating the light stability of solid-solution-based AgCl-AgBr and AgBr-TlI crystals

For the development of mid-infrared fiber-optical elements, one needs light-stable, flexible materials that are transparent within this spectral band. Solid solutions of silver and monadic thallium halides prove to be the most suitable crystalline media for these needs. We study the light stability variation of high-purity AgCl1-xBrx(0 ≤ x ≤ 1) and Ag1-xTlxBr1-xIx (0 ≤ x ≤ 0.05) crystals by measuring the optical transmission change as functions of the composition and UV exposure time. The former is executed in a broad spectral range from 6500 - 350 cm-1, within which we choose three wavelengths to trace the transmission change. For thalliummonoiodide-containing samples, an effect is observed that we assumed to be translucence. © 2016 Chinese Optics Letters

Effect of anodic oxygen evolution on cell morphology of sulfuric acid anodic alumina films

The purpose of this work was to study and analyze the effect of electrolyte temperature and anodization voltage on cell morphology of thin films of sulfuric acid anodic alumina formed on substrates of different nature, such as SiO2/Si, glass-ceramic, glass substrates, and polished aluminum. The data obtained demonstrated that the thermal conductivity of the substrate in the voltage range from 12 to 14 V affected a pore diameter (dpore) in anodic films. Depending on the substrate type, dpore increased in the following order: glass > glass- ceramic > SiO2/Si > aluminum. It was found that the anodizing voltage (Ua) of 16 V was a turning point for anodic films obtained in sulfuric acid after which the slope of the lines for both dpore and Dinter (interpore distance) vs. Ua changed. This behavior might be explained by the occurrence of the overpotential enough for the beginning of the oxygen evolution reaction. We assumed that the oxygen evolution on aluminum oxide surface at the pore bottom at Ua> 16 V results in an increase in acid concentration in the solution and, consequently, in rise in acidic nature of the electrolyte and increase in the dissolution rate of the oxide layer of pore walls

Имитационное моделирование фрагмента сети электросвязи специального назначения с технологией IPSec в сетевом симуляторе NS-3

Разработан класс для сетевого симулятора Network Simulator 3, имитирующий работу VPN-шлюза. Показано, что разработанный класс работает имитирует основные процессы протокола IPSec. A class for the network simulator Network Simulator 3 has been developed to simulate the operation of a VPN gateway. It is shown that the developed class works by simulating the basic processes of the IPSec protocol

Влияние природы органических растворителей на стабильность и активирующую способность коллоидных растворов SnCl2

The regularities of colloidal particles formation in the volume of acetone and glycol SnCl2 solutions in presence of a number of stabilizing additives have been investigated. It was found that in relation to oxidation and hydrolysis of Sn (II) acetone and glycol solutions are much more stable than aqueous and alcohol solutions. The factors influencing their mediation activity in relation to the fixation of an inorganic nitrogen-phosphorus-containing flame retardant on polyester matrix have been established. It has been proven that the formation of numerous homogeneous colloidal particles with sizes not exceeding 20-25 nm in the volume of SnCl2 solutions is a necessary condition for achieving a high mediating effect on fixing a fire retardant on a polyester surface.Исследованы закономерности формирования коллоидных частиц в ацетоновых и гликолевых растворах SnCl2 в присутствии ряда стабилизирующих добавок. Обнаружено, что ацетоновые и гликолевые растворы значительно более стабильны по отношению к окислению и гидролизу Sn(II), чем водные и спиртовые. Установлены факторы, влияющие на их медиативную активность по отношению к закреплению неорганического азот-фосфорсо-держащего замедлителя горения на полиэфирной матрице. Доказано, что необходимым условием достижения высокого медиативного эффекта по закреплению антипирена на полиэфирной поверхности является образование в объеме растворов SnCl2 многочисленных однородных коллоидных частиц с размерами, не превышающими 20-25 нм

Monitoring of Electrode Temperature in Exothermic Electrochemical Process

In this paper the features of temperature control of aluminum electrode during the anodization are discussed. Temperature monitoring in this exothermic process is a necessary condition for obtaining a high ordered nanoporous structure. A new electrochemical cell with a Peltier device working in cooling or heating mode was proposed. Time dependences of the electrolyte and Peltier element temperatures without and during anodizing process were presented. The results demonstrated that the cell construction allows precise control of the electrode temperature

FEATURES OF DIAGNOSTIC AND THERAPEUTIC TACTICS FOR BLUNT ABDOMINAL TRAUMA WITH DAMAGE TO THE PANCREAS

Abstract. Injuries of pancreas in the closed abdominal trauma remain the one of most challenging issues in diagnosis and choice of optimal therapy.Objectives. To analyze clinical results of the improved diagnostic and treatment tactics in patients with blunt abdominal trauma and damage to the pancreas.Material and methods. We report the results of treatment for 141 patients with pancreatic trauma treated from 1991 to 2015 at City Hospital No. 3 and City Hospital No. 40. All patients were divided into 2 groups. These groups were formed according to the time factor. The groups were comparable in age, gender, and pancreatic trauma severity. The study group consisted of 59 patients, treated in 2004-2015, and the comparison group consisted of 82 patients (1991–2003). The advanced diagnostic and treatment algorithm for the study group included modern instrumental diagnostic methods, such as ultrasound, computed tomography, diagnostic laparoscopy and improved surgical tactics to lower indications for omental plug, omentobursostomy, suturing capsule of pancreas and cholecystostomy.Results. This algorithm reduced the duration gap between hospitalization and surgery averagely from 10.7 to 4.0 hours, and the modified treatment tactics decreased the incidence of septic complications from 15.8% to 6.8%, and the mortality from 27.6% to 16.9%.Conclusion. As a rule, methods of radiodiagnosis detect only indirect signs of pancreatic injury in blunt abdominal trauma. It is advisable to perform omental plugging only as medical tactics of «damage control»

Study of microstructure of porous anodic alumina films formed in malonic acid in the wide range of aluminium anodizing voltages

In present paper the microstructure parameters of porous anodic alumina films formed by the anodizing of aluminum in the aqueous solution of malonic acid at different anodizing voltages was studied. The morphology of structured surface of aluminum film was studied using a scanning electron microscope after selective removal of anodic film. The results obtained for anodic films formed in malonic acid during anodizing in the range of 15-80 V allowed to determine that change in the interpore distance with the anodizing voltage is linear function with a slope of 1.45. The key conclusion was made that mechanical stress in anodic alumina layer is the main factor responsible for formation of the nanoporous structure of anodic alumina films

The sorption of water molecules in the pores of anodic alumina films during aluminum anodizing in oxalic acid

The thermogravimetric analysis of membranes of anodic aluminum oxide (AAO) was carried out. The results showed that in the process of anodic growth, water molecules are adsorbed in the pores of Al2O3, the amount of which is determined by the anodizing voltage of aluminum. The relationship is revealed and the graphs of the relationship between anodizing voltage, annealing temperature, and weight loss of nanostructured membranes of AAO are presented. It has been established that the adsorption of water molecules on the surface of AAO is explained by the presence of a surface charge, which disappears after annealing at 200–300 °C. An increase in the amount of adsorbed water with an increase in the anodizing voltage from 20 to 40 V indicates a decrease in the surface charge density