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Using the advanced acoustic emission (AE) technique, we address the problem of early identification of crack initiation and growth in ductile structural steels under cyclic loading. The notched 9MnSi5 steel specimens with weld joints were fatigue tested at room and lower temperatures with concurrent AE measurements. Detection of AE in ductile materials where fatigue crack initiation and propagation is mediated by local dislocation behavior ahead of the notch or crack tip is challenging because of an extremely low amplitude of the AE signal. With account of this issue, two new practically oriented criteria for recognition of different stages of fatigue are proposed on the basis of AE data: (1) a power spectrum-based criterion and (2) a pattern recognition-based criterion utilizing modern clustering algorithms. The applicability of both criteria is verified using obtained AE data. A good correspondence between AE outcomes and experimental observations of the fatigue behavior was obtained and is discussed.

Предложены концепция мобильного микробиоценоза синбиотопа против патогенов и базирующиеся на ней новые антимикробные стратегии. Мобильность синбиотопа определяется наличием кофункционирующих антимикробных путей, реализуемых с участием высокомолекулярных метаболитов культур пробиотических бактерий. Новые антипатогенные стратегии предполагают возможности отбора про-/синбиотических штаммов и консорциумов, продуцирующих эффективные ферментно-лектино-гликоконъюгатные системы.

Magnesium alloys have a unique combination of properties in terms of specific strength, modulus of elasticity and biocompatibility, which allows them to be considered as one of the most promising materials for use as temporary bioresorbable implants capable of being replaced by bone tissue in the process of gradual dissolution in the human body, thereby eliminating the need for repeated surgical intervention to remove the implant after healing. In this regard, the world scientific community pays much attention to works aimed at developing methods for controlling the corrosion damage of magnesium alloys. The present study demonstrates that such a precision control can be realized using vacuum zirconium coatings, while Zr itself is already actively used in medicine. It has been shown that the application of a zirconium coating on the MA14 (ZK60) alloy, which is currently considered as one of the possible candidates for use in medical practice, with thicknesses of 0.4 and 0.8 μm, can reduce the corrosion damage estimated by the hydrogen yield, based on 110 hours per 1.3 and 1.6 times, respectively. The favorable effect of the zirconium coating on the resistance to corrosion processes is confirmed by the results obtained using a laser confocal microscope: a decrease in both the total corroded area and the depth of corrosion damage was recorded in three-dimensional images of the sample surface. In addition, in the work using scanning electron microscopy, a comprehensive study of the obtained coatings is presented, which made it possible to characterize its structure and chemical composition. The adhesion characteristics of the coating were evaluated by scratching on a tester and showed that for a coating with a thickness of 0.8 μm, fracture is observed at an indentation load of the conical indenter of the order of 0.5 N.

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