Improvement of Sheet Metal Properties by Inducing Residual Stresses into Sheet Metal Components by Embossing and Reforming

In sheet metal forming, combination of embossing and reforming allows the mechanical properties of sheet metal materials to be specifically improved. Here, local property modification is achieved by the residual stresses induced as a result of the one-sided embossing process followed by a reforming step. The residual stresses induced in this specific way can lead to a significantly increase in the fatigue strength of processed sheet metal components. However, in order to ensure this kind of component optimization in continuous operation, the induced stresses have to be homogeneous. In this respect, the main objective of the study reported about in this paper was to identify a forming strategy, consisting of the process steps embossing and reforming, that generates preferably homogeneous residual stress distributions into sheet metal blanks. For this, numerical and experimental investigations were carried out with samples of the stainless steel (X6Cr17) having a thickness of 1.5 mm. It was found that embossing and reforming, integrated into a conventional forming process, is a novel approach to specifically induce very localized homogeneous compressive residual stresses in sheet metal materials. This eliminates the need for costly post-processing by means of surface treatment.

A unified synthetic strategy to introduce heteroatoms via electrochemical functionalization of alkyl organoboron reagents

Based on systematic electrochemical analyses, an integrated synthetic platform of C(sp3)-based organoboron compounds was established for the introduction of heteroatoms. The electrochemically mediated bond-forming strategy was shown to be highly effective for the functionalization of sp3-hybridized carbon atoms with significant steric hindrance. Moreover, virtually all the nonmetallic heteroatoms could be utilized as reaction partners using one unified protocol. The observed reactivity stems from the two consecutive single-electron oxidations of the substrate, which eventually generates an extremely reactive carbocation as the key intermediate. The detailed reaction profile could be elucidated through multifaceted electrochemical studies and the examination of the reaction kinetics. Ultimately, a new dimension in the activation strategies for organoboron compounds was accomplished through the electrochemically driven reaction development.

Cognitive dialogue as a human-forming strategy of education

Актуальность статьи обусловлена необходимостью определения развивающих, обучающих и воспитывающих векторов когнитивного диалога, сопряженных с человеко-мерностью знания, определяющей гуманистические смысловые приоритеты Человека современного противоречивого мира. Цель статьи - ввести понятие «когнитивный диалог» в проблемное поле когнитивной педагогики как человекообразующей стратегии педагогического взаимодействия, детерминирующего концептуально-ценностные образования гармоничного развития личности. Определены этапы развития диалогического самопознания в процессе когнитивного диалога в единстве логических и эмоционально-образных координат на материале художественных произведений.Результатом исследования явилась разработка принципов когнитивного диалога: принципа человекосообразности, обеспечивающего развитие гуманистической рефлексии взаимодействия в рамках интеллигентного сообщества субъектов образовательного процесса;принципа гармонической соразмерности, определяющего концептуальное гуманистическое осознание симметричного согласования личностных и социальных смыслов когнитивного развития человека и результативных правил их реализации в образовательной практике. Статья предназначена для педагогов, психологов, преподавателей вузов, исследователей в области современной педагогики. The relevance of the article is due to the need to determine the teaching, educating and developing vectors of cognitive dialogue, coupled with the human dimension of scientific knowledge, which determines the humanistic semantic priorities of the Man in the modern contradictory world. The purpose of the article is to introduce the concept of "cognitive dialogue" into the problem field of cognitive pedagogy as a human-forming strategy of pedagogical interaction, which determines the conceptual-value formations of the harmonious development of the individual. The stages of development of dialogical self-knowledge in the process of cognitive dialogue in the unity of logical and emotional-figurative coordinates on the material of works of art are determined. The result of the study was the development of effective principles of cognitive dialogue: human conformity, which ensures the development of humanistic reflection of interaction within the framework of the intelligent community of subjects of the educational process, harmonious proportionality, which determines the conceptual humanistic awareness of the symmetrical coordination of personal and social meanings of human cognitive development and the rules for their implementation in educational practice. The article is intended for teachers, psychologists, university-teachers, researchers in the field of modern pedagogy.

Thermodynamically driven self-formation of Ag nanoparticles in Zn-embedded carbon nanofibers for efficient electrochemical CO2 reduction

Ag nanoparticles in Zn-embedded carbon nanofiber were synthesized by a simple one-pot, self-forming strategy. Charged Zn single atoms act as Lewis acidic sites and improving the CO2 reduction reaction performance of the Ag nanoparticles.

Total Synthesis of Stemoamide, 9a-epi-Stemoamide, and 9a,10-epi-Stemoamide: Divergent Stereochemistry of the Final Methylation Steps

Total syntheses of stemoamide, 9a-epi-stemoamide, and 9a,10-epi-stemoamide by a convergent A + B ring-forming strategy is reported. The synthesis required a diastereoselective late-stage methylation of the ABC stemoamide core that successfully enabled access to three of the four possible diastereomeric structures. For the natural stemoamide series, the diastereoselectivity can be rationalized both by kinetic and thermodynamic arguments, whereas for the natural 9a-epi-stemoamide series, the kinetic selectivity is explained by the prepyramidalization of the relevant enolate.