Evaporation of Electrolyte During SVET Measurements: The Scale of the Problem and the Solutions

The objective of this work is to investigate the scale of the effect of spontaneous solution evaporation during SVET (Scanning Vibrating Electrode Technique) measurements and demonstrate how it biases the final results. When SVET maps are continuously acquired for more than several hours, the measured currents are smaller than expected. This is attributed to solvent (typically water) evaporation which leads to an increase in solution conductivity over time. If this is not considered when converting the measured potential differences into the local current densities, the SVET results display currents smaller than the true ones. Here, this effect is studied with a platinum disk electrode as source of a constant current and a model corroding system consisting of the AA2024/CFRP galvanic couple. Corrective actions are proposed to mitigate the problem, either in the experimental set‐up or as numerical correction

Uses of scanning electrochemical microscopy in corrosion research

This paper provides a brief review of a relatively new technique, namely scanning electrochemical microscopy (SECM), and its applications in measuring, characterising and evaluating corroding systems. Localized corrosion processes and electrochemical activity distributions in surfaces can thus be investigated in real time with high spatial resolution. The SECM is a unique near-field scanning technique that is electrochemically integrated as to detect chemical and electrochemical activities in electrochemical heterogeneous systems such as those operating in corrosion research. The SECM can be used in a variety of ways, which can be broadly classified into amperometric and potentiometric modes, depending on the type of the sensing probe, namely an ultramicroelectrode (UME) and an ion-selective microelectrode, respectively. The operation modes of the instrument are described together with typical experiments selected to illustrate their application in sensing localised corrosion

Thixomolded AZ91D and MRI153M magnesium alloys and their enhanced corrosion resistance

© 2020 The Authors. Materials and Corrosion published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim AZ91D and MRI153M alloys were produced by thixomolding. Their corrosion resistance is significantly higher than that of similar materials produced by ingot or die-casting. A corrosion rate smaller than 0.2 mm/year in 5 wt% NaCl solution is measured for the thixomolded AZ91D alloy. The corrosion behaviour was evaluated using immersion tests, electrochemical impedance spectroscopy, hydrogen evolution, glow discharge optical emission spectroscopy, and atomic emission spectroelectrochemistry. A bimodal microstructure is observed for both alloys, with the presence of coarse primary α-Mg grains, fine secondary α-Mg grains, β-phase, and other phases with a minor volume fraction. The amount of coarse primary α-Mg is significantly higher for the AZ91D compared with the MRI153M. The network of β-phase around the fine secondary α-Mg grains is better established in the thixomolded AZ91D alloy. A combination of several factors such as the ratio of primary to secondary α-Mg grains, localised corrosion or barrier effect due to other phases, as well as regions of preferential dissolution of the α-Mg due to chemical segregation, are thought to be responsible for the high corrosion resistance exhibited by the thixomolded AZ91D and MRI153M.German Ministry of Education and Research; Christian Doppler Societ

Вакциносодержащая безблистерная приманка для пероральной иммунизации плотоядных животных против бешенства

Rabies is absolutely lethal acute viral disease that affects humans and all warm-blood animals, which is common in many countries of the world, including Belarus. Wild carnivorous animals, mainly foxes, are the main source of rabies virus infection, therefore development and improvement of means and methods for preventing this disease among wild carnivores, in particular oral immunization of carnivorous animals, is of great research and practical importance. Anti-rabies vaccine was developed for oral use in the form of a blister-free bait consisting of fixed rabies virus selected by us – strain KMIEV-94 (71 BelNIIEV–VGNKI M), meat and bone meal and wheat flour, gelatin, glycerin and tetracycline. Technology for manufacture of improved highly immunogenic blister-free vaccine-containing bait for oral vaccination of wild carnivorous animals against rabies was developed. Immunological and anti-epizootic efficiency of vaccine-containing baits was studied. It was determined that use of the developed vaccine-containing blister-free anti-rabies bait in natural conditions is ecologically safe, since KMIEV-94 rabies virus is deeply attenuated and apathogenic for rodents and carnivorous animals after oral administration, does not have reversibility and after 9 days of storing the bait at a temperature of 18–20 °C is inactivated. High efficiency, safety, simple manufacturing technology of the developed bait indicate prospects of its introduction into practice, which will reduce the incidence of rabies in animals. Бешенство – абсолютно смертельное острое вирусное заболевание, поражающее человека и всех теплокровных животных, которое распространено во многих странах мира, в том числе и в Беларуси. Основным источником заражения вирусом бешенства являются дикие плотоядные животные, главным образом лисицы, поэтому разработка и усовершенствование средств и методов профилактики указанного заболевания среди диких плотоядных животных, в частности пероральной иммунизации плотоядных животных, имеет важное научно-практическое значение. Сконструирована антирабическая вакцина для перорального применения в форме безблистерной приманки, состоящей из селекционированного нами фиксированного вируса бешенства – штамм КМИЭВ-94 (71БелНИИЭВ–ВГНКИ М), мясокостной и пшеничной муки, желатина, глицерина и тетрациклина. Разработана технология изготовления усовершенствованной высокоиммуногенной безблистерной вакциносодержащей приманки для пероральной вакцинации диких плотоядных животных против бешенства. Изучены иммунологическая и противоэпизоотическая эффективности вакциносодержащих приманок. Установлено, что применение разработанной вакциносодержащей безблистерной антирабической приманки в природных условиях экологически безопасно, так как входящий в ее состав вирус бешенства «КМИЭВ-94» является глубоко аттенуированным, апатогенным для мышевидных грызунов и плотоядных животных при пероральном введении, не обладает реверсибельностью и через 9 дней хранения приманки при температуре плюс 18–20 °С инактивируется. Высокая эффективность, безвредность простата технологии изготовления разработанной приманки свидетельствуют о перспективности ее внедрения в практику, что позволит снизить заболеваемость животных бешенством

Метод прогнозирования углов ориентации научной аппаратуры при съемке с борта международной космической станции с использованием платформы наведения

Onboard the International Space Station (ISS), as a part of the “Uragan” Earth exploration experiment, various observation devices are used, including photo and video spectral equipment, the orientation of which is carried out manually by the crew through the portholes. However, severe limitations are imposed on the planning of such experiments, primary related to the necessity taking into account the crew’s daily routine and the availability of time allocated for scientific experiments. The solution for expanding the ability to conduct experiments is the employing of automated orientation platforms (OP). One of these OPs is the video spectral equipment orientation system SOVA-1-426. A method for orientation angles forecasting of optical instruments for pointing at predefined objects on the Earth’s surface with SOVA-1-426 is presented. Moreover, in the described method, in addition to the coordinates of the center of mass, the current orientation of the ISS is taken into account, which makes it possible to perform the forecast with better precision. Taking into account the ISS orientation is carried out through the use of the ISS rotation quaternion to control the platform in automatic mode. The presented method for the orientation angles forecasting of high-resolution photo-camera aboard the ISS by employing SOVA-1-426 allows its automatic alignment on the Earth’s surface objects with accuracy up to seven kilometers. The described method is implemented in software and is currently used in the SOVA-1-426 OP aboard the ISS for the remote sensing of the Earth’s surface.На борту Международной космической станции (МКС) в рамках эксперимента «Ураган» по исследованию Земли используются различные приборы наблюдения, в том числе фотографическая, фото- и видеоспектральная аппаратура, наведение которой проводится экипажем вручную через иллюминаторы. Однако на планирование таких экспериментов налагаются сильные ограничения, прежде всего связанные с необходимостью учета распорядка дня экипажа и наличия у него времени, выделенного на проведение научных экспериментов. Решением, позволяющим расширить возможности по проведению экспериментов, является использование автоматизированных платформ наведения (ПН). Одной из таких ПН является система ориентации видеоспектральной аппаратуры СОВА-1-426. В работе представлен метод вычисления углов ориентации научной аппаратуры для наведения на заранее заданные объекты земной поверхности с использованием СОВА-1-426. При этом в описанном методе помимо координат центра масс учитывается текущая ориентация МКС, что позволяет сделать прогноз более точным. Учет ориентации МКС достигается за счет использования кватерниона разворота МКС для наведения платформы в автоматическом режиме. Представленный метод расчета углов ориентации научной аппаратуры при съемке с борта МКС с использованием СОВА-1-426 позволяет с точностью не более 7 км осуществлять наведение на объекты земной поверхности с борта МКС. Описанный метод реализован программно и в настоящее время используется в ПН СОВА-1-426 на борту МКС для съемки объектов земной поверхности

Characterization of Siloxane-poly(methyl methacrylate) Hybrid Films Obtained on a Tinplate Substrate Modified by the Addition of Organic and Inorganic Acids

Tinplate is used to food packaging and other types of packages. The corrosion resistance of the tinplate has been study due the necessity of an alternative to high environmental impact of chromatization process. Therefore protective coatings as hybrid films base elaborations with different acids are studied to improve the barrier effect against corrosion. The objective of this work is characterize hybrid films deposited on a tinplate from a sol made up of the alkoxide precursors 3-(trimethoxysilylpropyl) methacrylate (TMSM), tetraethoxysilane (TEOS) and poly(methyl methacrylate) (PMMA) together with one of three acids (acetic, hydrochloric or nitric acid) and to verify their action against the corrosion of the substrate. The films were obtained by a dip-coating process and cured for 3 hours at 160 °C. The film hydrophobicity was determined by contact angle measurements, and the morphology was evaluated by SEM. FTIR measurements were performed to characterize the chemical structures of the films. The electrochemical behavior of the coatings was evaluated by techniques open circuit potential monitoring (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results demonstrate that the siloxane-PMMA films improve the protective properties of the tinplate, with the films obtained by acetic acid addition exhibiting the greatest improvement

Synergistic protection against corrosion of AA2024-T3 by sol-gel coating modified with La and Mo-enriched zeolites

The present work demonstrates an improvement in corrosion protection of sol-gel coatings modified with a mixture of lanthanum and molybdate-enriched zeolite microparticles (La+Mo) due to synergistic effect between lanthanum and molybdate. The effect of these inhibitor species on protection of AA2024-T3 substrate has been studied by Electrochemical Impedance Spectroscopy and Localized Electrochemical Impedance Spectroscopy. Both techniques revealed an enhanced protection when compared with the case where the inhibitors were used alone. The inhibiting mechanism could involve on demand release of molybdate and lanthanum ions from the loaded zeolite followed by the formation of molybdenum oxide/hydroxide and a Mo-Na-La compound on intermetallic particles