A phenomenological model of macrocrack initiation and growth in cyclically deformed material

Role of the process zone in fatigue macrocrack initiation and propagation is considered. An examples of the assessment of the fatigue macrocrack initiation period, Ni, and the failure period, Nf, of a notched specimens on the base of unified model using fatigue macrocrack growth rates only are shown. Some backgrounds and well-known fatigue phenomena (Kitagawa's and Smith's diagrams, etc) are discussed

Electrochemical diagnostics of the structural-phase state of pipelanes steels at durable operation

Показано, що внаслідок неоднорідного напружено-деформованого стану згинів парогонів зі сталей 12Х1МФ та 15Х1М1Ф у різних зонах (розтягнута, середня, стиснена) процеси трансформації структури і накопичення пошкоджуваності в процесі експлуатації проходить з різною інтенсивністю. Встановлено, що стандартні механічні характеристики, передбачені діючими нормативними документами, виявляють слабку чутливість (знижуються в 1.03-1.24 раза) до процесів зміни мікроструктури та накопичення пошкоджень за умови повзучості сталей 12Х1МФ і 15Х1М1Ф. З іншого боку, зміни фазового складу та мікроструктури парогінних сталей суттєво впливають на їх електрохімічну поведінку, зокрема, на швидкість репасивації свіжоутвореної поверхні Vr.It is shown that the processes of structure transformation and damage evolution under service conditions passes with different intensity as a result of nonuniform stress-strain state in different zones (tensile, middle, compressed) of the bends of 12Х1МФ or 15Х1М1Ф steel pipelines. It is established that standard mechanical properties, provided by current normative documents, exhibit weak sensitivity (decrease in 1.03–1.24 times) to the processes of the microstructure change and damage accumulation under creep conditions of 12Х1МФ and 15Х1М1Ф steels. On the other hand, phase composition and microstructure change of pipeline steels has a significant influence on their electrochemical behaviour, in particular, on the fresh surface repassivation rate Vr

Chemical Approaches To Perturb, Profile, and Perceive Glycans

Glycosylation is an essential form of post-translational modification that regulates intracellular and extracellular processes. Regrettably, conventional biochemical and genetic methods often fall short for the study of glycans, because their structures are often not precisely defined at the genetic level. To address this deficiency, chemists have developed technologies to perturb glycan biosynthesis, profile their presentation at the systems level, and perceive their spatial distribution. These tools have identified potential disease biomarkers and ways to monitor dynamic changes to the glycome in living organisms. Still, glycosylation remains the underexplored frontier of many biological systems. In this Account, we focus on research in our laboratory that seeks to transform the study of glycan function from a challenge to routine practice

Minimum Information about a Biosynthetic Gene cluster

A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard.Chemistry and Chemical Biolog