Search

Abstract This study examines the optimization and characterization of stoichiometric and carbon‐free boron nitride interphase coatings using triethylamine borane complex as a precursor in the Fluidized Bed Chemical Vapor Deposition process. It highlights the importance of optimizing chemical vapor deposition parameters to control coating formation, limit carbon contamination, and assess the feasibility of stoichiometric boron nitride from triethylamine borane complex coatings. The study investigates the thermal decomposition of triethylamine borane complex and its effect on carbon contamination through theoretical thermodynamic calculations, corroborated by Fourier‐transform infrared spectroscopy. Analysis shows a consistent, uniform microstructure. Auger electron spectroscopy and X‐ray photoelectron spectroscopy confirm the presence of boron, nitrogen, carbon, and oxygen, with negligible carbon inclusions. Transmission electron microscopy and electron energy loss spectroscopy reveal a low‐crystalline, isotropic structure. Carbon‐rich areas in boron nitride coatings indicate intricate chemical interactions during deposition, while disordered structures highlight the need to understand the effects of structural variations. Despite using a high‐carbon precursor, boron nitride coatings are remarkably stoichiometric with low carbon and oxygen contamination, demonstrating the benefits of non‐chlorinated precursors.

In multicellular eukaryotic organisms, the initiation of DNA replication occurs asynchronously throughout S-phase according to a regulated replication timing program. Here, using Xenopus egg extracts, we showed that Yap (Yes-associated protein 1), a downstream effector of the Hippo signalling pathway, is required for the control of DNA replication dynamics. We found that Yap is recruited to chromatin at the start of DNA replication and identified Rif1, a major regulator of the DNA replication timing program, as a novel Yap binding protein. Furthermore, we show that either Yap or Rif1 depletion accelerates DNA replication dynamics by increasing the number of activated replication origins. In Xenopus embryos, using a Trim-Away approach during cleavage stages devoid of transcription, we found that either Yap or Rif1 depletion triggers an acceleration of cell divisions, suggesting a shorter S-phase by alterations of the replication program. Finally, our data show that Rif1 knockdown leads to defects in the partitioning of early versus late replication foci in retinal stem cells, as we previously showed for Yap. Altogether, our findings unveil a non-transcriptional role for Yap in regulating replication dynamics. We propose that Yap and Rif1 function as brakes to control the DNA replication program in early embryos and post-embryonic stem cells.