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Aggregation of \beta -amyloid ( \text{A}\beta ) is one of the early events in Alzheimer’s disease (AD) pathology and is considered to initiate the amyloid cascade. It is presumed that \text{A}\beta plaque might coexist with biogenic magnetite. In order to understand the combined effect and mechanism of the biogenic magnetite and \textA\beta in AD, it is necessary to clarify the role of the magnetite in \textA\beta aggregation. Due to the magnetic characteristic of the magnetite, it possibly mediates the effect of environmental magnetic field (MF) on \textA\beta aggregation. Here, we preliminarily characterized the morphology of \textA\beta 40 aggregation coincubated with a magnetic nanoparticle coated with SiO2 (MNP-SiO2) in the presence of an external extremely low-frequency MF (ELF MF) exposure. Coincubation with MNP-SiO2 accelerated \textA\beta 40 aggregation and MF exposure led to more heterogeneous \textA\beta species. The results indicated that the exposure of ELF MF and MNP-SiO2 could alter the \textA\beta 40 aggregation. It will provide insights to understand the roles of ELF MF exposure and biogenic magnetite in the AD pathology. [ABSTRACT FROM AUTHOR]

In contrast to the conventional forced wave generator which consists of cam and flexible bearing in harmonic drive, the novel forced wave generator retains cam but cancels flexible bearing. In this article, the lubrication characteristics of the novel forced wave generator in harmonic drive is studied. First, an elliptical sliding bearing (ESB) model of simplified structure between the novel forced wave generator and the flex spline is established. Further, the computational fluid dynamics (CFD) method is employed to study the effect of some factors on the lubrication characteristics of the ESB model including elliptical gap ratio, width, and rotational speed. According to the analysis, the elliptical gap ratio has a great impact and its optimal value is 3, which is used in the design of the novel forced wave generator. Last, the practical design of the novel forced wave generator in harmonic drive is given, which can provide a basis for design and optimization of a forced wave generator without flexible bearing of the harmonic drive. [ABSTRACT FROM AUTHOR]

We confirm the previously revised stereochemistry of spiroviolene by X-ray crystallographically characterizing a hydrazone derivative of 9-oxospiroviolane, which is synthesized by hydroboration/oxidation of spiroviolene followed by oxidation of the resultant hydroxy group. An unexpected thermal boron migration occurred during the hydroboration process of spiroviolene that resulted in the production of a mixture of 1α-hydroxyspiroviolane, 9α- and 9β-hydroxyspiroviolane after oxidation. The assertion of the cis -orientation of the 19- and 20-methyl groups provided further support for the revised cyclization mechanism of spiroviolene., (Copyright © 2024, Kong et al.)