Applications of Scanning Electron Microscopy Using Secondary and Backscattered Electron Signals in Neural Structure

Koga, Daisuke; Kusumi, Satoshi; Shibata, Masahiro; Watanabe, Tsuyoshi

doi:10.3389/fnana.2021.759804

Cited by 17 publications

(9 citation statements)

References 58 publications

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“…The BSE image in Figure a displays a cellular contrast, well-known in biological microscopy, due to contrast agent staining. The SIMS images in Figure b,c enable us to localize a fluorinated environmental pollutant (in red) and the cells (in green).…”

Section: Resultsmentioning

confidence: 99%

Magnetic Sector Secondary Ion Mass Spectrometry on FIB-SEM Instruments for Nanoscale Chemical Imaging

et al. 2022

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The structural, morphological, and chemical characterization of samples is of utmost importance for a large number of scientific fields. Furthermore, this characterization very often needs to be performed in three dimensions and at length scales down to the nanometer. Therefore, there is a stringent necessity to develop appropriate instrumentational solutions to fulfill these needs. Here we report on the deployment of magnetic sector secondary ion mass spectrometry (SIMS) on a type of instrument widely used for such nanoscale investigations, namely, focused ion beam (FIB)–scanning electron microscopy (SEM) instruments. First, we present the layout of the FIB-SEM-SIMS instrument and address its performance by using specific test samples. The achieved performance can be summarized as follows: an overall secondary ion beam transmission above 40%, a mass resolving power ( M /Δ M ) of more than 400, a detectable mass range from 1 to 400 amu, a lateral resolution in two-dimensional (2D) chemical imaging mode of 15 nm, and a depth resolution of ∼4 nm at 3.0 keV of beam landing energy. Second, we show results (depth profiling, 2D imaging, three-dimensional imaging) obtained in a wide range of areas, such as battery research, photovoltaics, multilayered samples, and life science applications. We hereby highlight the system’s versatile capability of conducting high-performance correlative studies in the fields of materials science and life sciences.

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Section: Resultsmentioning

confidence: 99%

Magnetic Sector Secondary Ion Mass Spectrometry on FIB-SEM Instruments for Nanoscale Chemical Imaging

et al. 2022

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“…To understand the mechanism of action of EIPE-1, SEM and TEM analyses were conducted. SEM and TEM can provide vital information about the surface and internal structures of cells ( Nixon, 1964 ; Koga et al, 2021 ). Cryptococcus neoformans strain H99 cells were incubated with EIPE-1 at 4 h, 8 h, or 12 h, following which cells were prepared for electron microscopy.…”

Section: Resultsmentioning

confidence: 99%

Antifungal activity of eumelanin-inspired indoylenepheyleneethynylene against Cryptococcus neoformans

Conn,

Lieberman,

Chatman

et al. 2024

Front. Microbiol.

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Cryptococcus neoformans is an opportunistic fungal pathogen that causes meningitis in >152,000 immunocompromised individuals annually, leading to 112,000 yearly deaths. The four classes of existing antifungal agents target plasma membrane sterols (ergosterol), nucleic acid synthesis, and cell wall synthesis. Existing drugs are not highly effective against Cryptococcus, and antifungal drug resistance is an increasing problem. A novel antimicrobial compound, a eumelanin-inspired indoylenepheyleneethynylene, EIPE-1, was synthesized and has antimicrobial activity against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MSRA), but not towards Gram-negative organisms. Based on EIPE-1’s antibacterial activity, we hypothesized that EIPE-1 could have antifungal activity. For these studies, we tested EIPE-1 against C. neoformans strain H99 and 6 additional cryptococcal clinical isolates. We examined antifungal activity, cytotoxicity, effects on fungal gene expression, and mechanism of action of EIPE-1. Results showed that EIPE-1 has fungicidal effects on seven cryptococcal strains with MICs ranging from 1.56 to 3.125 μg/mL depending on the strain, and it is non-toxic to mammalian cells. We conducted scanning and transmission electron microscopy on the exposed cells to examine structural changes to the organism following EIPE-1 treatment. Cells exposed displayed structural changes to their cell wall and membranes, with internal contents leaking out of the cells. To understand the effect of EIPE-1 on fungal gene expression, RNA sequencing was conducted. Results showed that EIPE-1 affects several processes involved stress response, ergosterol biosynthesis, capsule biosynthesis, and cell wall attachment and remodeling. Therefore, our studies demonstrate that EIPE-1 has antifungal activity against C. neoformans, which affects both cellular structure and gene expression of multiple fungal pathways involved in cell membrane stability and viability.

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“…These dark areas are assumed to be typical surface degrading compounds with lightweight elements such as LiOH and Li 2 CO 3 because more backscattered electrons (BSEs) are emitted from heavier elements such as Ni, Co, or Mn than those from Li during BSE mode FE‐SEM. [ 25 ] In the case of the bare NCM811, exposure to regular air and elevated moisture air appeared to achieve the highest level of degradation on the particle surface as characterized by the dark substance formations that can be seen in Figure b,c. As a recoverability test, the bare NCM811 sample was heated again at 400 °C after the degradation experiments to check if the degradation contaminant compounds could be removed via this method.…”

Section: Resultsmentioning

confidence: 99%

Air‐ and Moisture Robust Surface Modification for Ni‐Rich Layered Cathode Materials for Li‐Ion Batteries

Embleton

Yun

Choi

et al. 2023

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long-range electric vehicle applications, especially those with high Ni contents as they deliver high capacity under the same operation protocol. [1][2][3] However, this increase in Ni content brings with it a rapid capacity fade and a shorter overall battery lifetime. [4][5][6] This capacity fade is linked to the oxygen loss at highly delithiated states. The occurrence of the oxygen loss is related to the unstable Ni ions that propagate from the surface of the NCM material into the bulk. This adverse effect is significantly promoted particularly in high-Ni NCM materials (Ni ≥ 80%). [7,8] When exposed to ambient environmental conditions, degradation of high-Ni NCM occurs from the surface, generating problematic residual lithium compounds. [9] The reaction of high-Ni NCM with H 2 O and CO 2 of the ambient air spawns a variety of the inhibiting lithium compounds on the surface. [10][11][12] Surface carbonates such as Li 2 CO 3 and surface hydroxides such as LiOH deteriorate the initial capacity and cyclability as they can result in unwanted side reactions and gas production during charge/discharge cycles. [13,14] The surface contaminants can also accelerate electrolyte decomposition and hamper the cycle capabilities. These surface contaminants are one of the key problems affecting the battery manufacturing industry. [15] Determinations of the exact degradation mechanisms have been attempted to promote understanding and develop potential mitigation strategies. Jung et al. showed that the extreme ambient degradation associated with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) is due to the presence of Ni, which then leads to the extraction of Ni from the layered structure. [10] The findings were impactful in developing the idea that surface contaminants may be formed along with structural degradation of the cathode; however, the work was unable to offer a standalone solution to the problem. Strategies to overcome surface degradation in general are numerous, however, strategies to prevent ambient atmosphere exposure-based surface degradation are limited. Liu et al. suggest a recovery method via heating the NCM at 725 °C to achieve a full recovery of the material. [16] This was successful, however, requiring a recovery step is undesirable for battery cell manufacturers and still requires a completely inert atmosphere after heating and during cell manufacturing to prevent further degradation. Furthermore, the posttreatment of NCM materials after storage was proven to eventually lead The mainstream of high-energy cathode development is focused on increasing the Ni-ratio in layered structured cathode materials. The increment of the Ni portion in the layered cathode material escalates not only the deliverable capacity but also the structural degradation. High-Ni layered cathodes are highly vulnerable to exposure to air that contains CO 2 and H 2 O, forming problematic residual lithium compounds at the surface. In this work, a novel air-and moisture robust surface modification is reported for LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) via ...

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Applications of Scanning Electron Microscopy Using Secondary and Backscattered Electron Signals in Neural Structure

Cited by 17 publications

References 58 publications

Magnetic Sector Secondary Ion Mass Spectrometry on FIB-SEM Instruments for Nanoscale Chemical Imaging

Magnetic Sector Secondary Ion Mass Spectrometry on FIB-SEM Instruments for Nanoscale Chemical Imaging

Antifungal activity of eumelanin-inspired indoylenepheyleneethynylene against Cryptococcus neoformans

Air‐ and Moisture Robust Surface Modification for Ni‐Rich Layered Cathode Materials for Li‐Ion Batteries

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