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The electrochemistry of Sn(II) was investigated with cyclic voltammetry and chronoamperometry in the 1-ethyl-3-methylimidazolium tetrafluoroborate molten salt containing free chloride ions (EMI ⋅BF4 ⋅Cl) originated from the mixture of EMIC and NaBF4 (60:40 mol%). The well defined redox waves for the electro deposition and dissolution of tin were observed on a platinum electrode at 303 K. The deposition of tin proceeded through a quasi-reversible step with two electron transfer, and the deposited tin was sufficiently recovered during oxidation. The experimental current-time transient coincided with the theory based on one-dimensional diffusion control.

Sensorineural hearing loss is usually intractable because of virtually no capacity for hair cell (HC) regeneration in mammals. In contrast to mammals, lower vertebrates including birds have the capability for HC regeneration. Elucidation of precise mechanisms for HC regeneration in avian auditory epithelia will contribute to exploring key molecules for inducing HC regeneration in mammals. We previously established an explant culture model of the chick auditory epithelium, namely basilar papilla (BP), showing total HC loss and consecutive HC regeneration through direct conversion of supporting cells (SCs) to HCs (Matsunaga, 2020). Single-cell RNA sequencing using this model illustrated dynamic changes in expressed genes in BP SCs during direct conversion, which indicates that reprogramming of SCs to the precursor state occurs before differentiation into HCs (Matsunaga, 2023). To explore mechanisms of SC reprogramming toward hair cell regeneration in chick BP, we performed an integrated analysis of RNA- and ATAC-seq of chick BP explant cultures during the early phase (three time points) of HC regeneration. ATAC sequencing detected 80,366 peaks. Based on the distance from the transcription start site, and correlations between read counts and peak depths and between their alterations in a time course, we determined enhancer candidate loci for differentially expressed genes. We focused on a set of temporally upregulated genes during SC reprogramming in our previous single-cell RNA sequencing data (Matsunaga, 2023). In temporally upregulated genes during SC reprogramming, enhancer candidate loci were identified in nine genes. Motif enrichment analysis of these loci indicated transcription factors that may control chromatin remodeling in SC reprogramming. In the near future, we will examine spaciotemporal expression patterns of these transcription factors in regenerating chick BP. [ABSTRACT FROM AUTHOR]

Although mammalian cochleae have no capacity for hair cell (HC) regeneration, the avian auditory epithelium, namely basilar papilla (BP), can regenerate HCs through direct conversion of supporting cells (SCs) or mitotic proliferation of SCs. To explore molecular mechanisms for HC regeneration in chick BP, we previously established an explant culture model of chick BP, in which HC regeneration occurs predominantly via direct conversion of SCs (Matsunaga et al., 2020) and performed single-cell RNA sequencing (Matsunaga et al., 2023) by using our model. A pseudotime trajectory analysis for the process of SC-to-HC conversion revealed that SCs were once reprogrammed to the precursor state, followed by differentiation into HCs (Matsunaga et al., 2023). In addition, we observed temporal upregulation of EDNRB2 encoded en-dothelin receptor b2 in reprogrammed SCs as differentially expressed genes during SC-to-HC conversion. In the current study, we examined the expression patterns of EDNRB2 in the developing chick BP to determine which stage progenitor or precursor populations express EDNRB2. The expression of EDNRB2 in BP was found only in the time points when HC differentiation was initiated, not in common progenitors for HCs and SCs or immature HCs and SCs after fate determination. The result supports our hypothesis that EDNRB2 is a marker for HC precursors and indicates that SCs are re-programmed to the precursor state just before fate determination, not to the common progenitor state. We also assessed the roles of EDNRB signaling during SC-to-HC conversion in regenerating chick BP explants using a selective inhibitor for EDNRB signaling. The pharmacological inhibition of EDNRB signaling significantly reduced the number of regenerated HCs, not reduced the number of SCs, which indicates that EDNRB signaling may play a role in the differentiation of precursors into HCs. Further, RNA sequencing is underway to identify the critical molecules downstream of EDNRB signaling. In conclusion, EDNRB2 is a novel marker for HC precursors in chick auditory epithelia and may be involved in HC differentiation. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the photoreflectance (PR) signal of n-type gallium arsenide grown by molecular-beam epitaxy as a function of modulation frequency in the PR measurements. Methodology of the study; Results and discussion; Conclusions.

Discusses a study on the surface Fermi level in gallium arsenide using photoreflectance (PR) spectroscopy. Theoretical background; PR spectra of the fundamental band edge; Advantages of the PR technique.

This paper presents a theory and related experiments on centrifugal barrel finishing. A calculation for the centrifugal force in the barrel is described. The limitation of the ratio between the rotation speed of the tubs and turrets, and values of polishing efficiency are determined by the calculation and compared with experimental results. It can be understood from the results why the polishing efficiency of the centrifugal barrel is far higher than that of the ordinary rotating barrel. Finally some considerations on design criteria are mentioned. [ABSTRACT FROM AUTHOR]