Hasil untuk "Microscopy"

Claudia Errico, J. Pierre, S. Pezet et al.

D. Ciresan, A. Giusti, L. Gambardella et al.

W. Melitz, Jian Shen, A. Kummel et al.

V. Ntziachristos

J. Dubochet, M. Adrian, Jiin-Ju Chang et al.

G. Palade

Osmium tetroxide fixation of tissue blocks, as usually effected, is preceded by an acidification of the tissue. This acidification is probably responsible for morphological alterations which are notably disturbing in electron microscopy. The acidification and the resulting morphological alterations cannot be prevented by homogenizing the tissue directly in OsO4 solutions or by adding enzyme inhibitors (fluoride, iodoscetamide) to the fixative. Fixation experiments with buffered OsO4 solutions have shown that the appearance of the fixed cells is conditioned by the pH of the fixative. The quality of fixation can be materially improved by buffering the OsO4 solutions at pH 7.3-7.5, The acetate-veronal buffer appeared to be the most favorable of the buffers tested, Because of these findings, 1 per cent OsO4 buffered at pH 7.3-7.5 with acetate-veronal buffer is recommended as an appropriate fixative for electron microscopy.

H. Dai, J. Hafner, A. Rinzler et al.

Hao F. Zhang, K. Maslov, G. Stoica et al.

F. Giessibl

This article reviews the progress of atomic force microscopy in ultrahigh vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows us to image surfaces of conductors and insulators in vacuum with atomic resolution. The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation atomic force microscopy (FM-AFM). This technique, as well as other dynamic methods, is explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened our theoretical understanding of frequency-modulation atomic force microscopy. Consequently spatial resolution and ease of use have been increased dramatically. Vacuum atomic force microscopy opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.

Na Ji

R. Heintzmann, T. Huser

A. Wassie, Yongxin Zhao, E. Boyden

Fuyong Xing, Yuanpu Xie, H. Su et al.

Computerized microscopy image analysis plays an important role in computer aided diagnosis and prognosis. Machine learning techniques have powered many aspects of medical investigation and clinical practice. Recently, deep learning is emerging as a leading machine learning tool in computer vision and has attracted considerable attention in biomedical image analysis. In this paper, we provide a snapshot of this fast-growing field, specifically for microscopy image analysis. We briefly introduce the popular deep neural networks and summarize current deep learning achievements in various tasks, such as detection, segmentation, and classification in microscopy image analysis. In particular, we explain the architectures and the principles of convolutional neural networks, fully convolutional networks, recurrent neural networks, stacked autoencoders, and deep belief networks, and interpret their formulations or modelings for specific tasks on various microscopy images. In addition, we discuss the open challenges and the potential trends of future research in microscopy image analysis using deep learning.

O. Couture, V. Hingot, B. Heiles et al.

Because it drives the compromise between resolution and penetration, the diffraction limit has long represented an unreachable summit to conquer in ultrasound imaging. Within a few years after the introduction of optical localization microscopy, we proposed its acoustic alter ego that exploits the micrometric localization of microbubble contrast agents to reconstruct the finest vessels in the body in-depth. Various groups now working on the subject are optimizing the localization precision, microbubble separation, acquisition time, tracking, and velocimetry to improve the capacity of ultrasound localization microscopy (ULM) to detect and distinguish vessels much smaller than the wavelength. It has since been used in vivo in the brain, the kidney, and tumors. In the clinic, ULM is bound to improve drastically our vision of the microvasculature, which could revolutionize the diagnosis of cancer, arteriosclerosis, stroke, and diabetes.

Bilal Tasdemir, Svitlana Krüger, Pinank Sohagiya et al.

The growing demand for higher-energy lithium-ion batteries, encompassing consumer electronics, stationary grid storage, and electric mobility to specialized sectors like aerospace, medical devices, and industrial robotics, requires cathode materials that offer higher capacity while remaining cost-effective. This trend has intensified the development of nickel-rich LiNi_1−x−yMn_xCo_yO₂ (NMC) systems. However, high-Ni NMCs such as LiNi_0.9Mn_0.05Co_0.05O₂ (NMC90) suffer from limited thermal and cycling stability. Core–shell architectures using LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) as a shell can partially alleviate these drawbacks, but structural degradation caused by interdiffusion between the core and shell persists as a major challenge. This study investigates whether a tungsten oxide interlayer can act as a protective barrier that suppresses interdiffusion, stabilizes the crystal structure, and improves long-term electrochemical performance. In this work, NMC cathode powders were synthesized via a one-pot oxalate co-precipitation route, followed by structural characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ion scattering spectroscopy (ISS). Electrochemical performance, including capacity retention, cycling stability, and internal resistance, was evaluated through galvanostatic charge–discharge (GCD) testing and electrochemical impedance spectroscopy (EIS). The core–shell configuration delivered higher specific discharge capacity compared to the individually synthesized core-only and shell-only reference materials, and the incorporation of a tungsten oxide interlayer resulted in a twofold increase in cycle life. These results demonstrate that tungsten oxide effectively enhances cycling stability by inhibiting core–shell interdiffusion, offering a promising pathway toward more durable high-Ni NMC cathodes.

Matheus Alexandre de Vasconcelos, Júlia Audrem Gomes de Oliveira Fadul, Vitor da Silva de Souza et al.

This study investigated the fabrication and characterization of biodegradable monofilament suture threads based on cellulose acetate (CA), plasticized with triethyl citrate (TC) and reinforced with poly(lactic acid) (PLA), produced by twin-screw micro-extrusion for potential dental surgical applications. The effects of TC content (25, 30, and 35 wt%) and PLA incorporation (15 wt%) on processability, thermal behavior, morphology, mechanical properties, and biocompatibility were systematically evaluated. The sutures were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile testing, and in vitro biological assays using RAW 264.7 macrophages. The results showed that TC effectively reduced the glass transition temperature of CA, enhancing flexibility and processability, while PLA incorporation influenced thermal stability and promoted morphological changes, including increased porosity and elasticity. SEM analyses revealed smooth and homogeneous surfaces for CA/TC monofilaments and slightly rougher, more porous morphologies for CA/PLA/TC blends, which may favor tissue interaction. In vitro assays confirmed cytocompatibility, with no cytotoxic effects or nitric oxide induction observed over a 7-day exposure period. Although most formulations did not fully meet the tensile strength requirements specified by NBR 13904/2003, the formulation containing 25 wt% TC and 15 wt% PLA (A4) exhibited the best mechanical performance, approaching normative values while maintaining suitable handling characteristics. Overall, the results indicate that CA/TC/PLA-based sutures represent a promising, sustainable, and biocompatible alternative for absorbable surgical sutures, although further optimization is required to fully comply with mechanical regulatory standards.

Inna Kviatkovsky, H. Chrzanowski, E. Avery et al.

Quantum light enables mid-IR microscopy with fast acquisition and ultralow intensities using a standard CMOS camera. Owing to its capacity for unique (bio)-chemical specificity, microscopy with mid–infrared (IR) illumination holds tremendous promise for a wide range of biomedical and industrial applications. The primary limitation, however, remains detection, with current mid-IR detection technology often marrying inferior technical capabilities with prohibitive costs. Here, we experimentally show how nonlinear interferometry with entangled light can provide a powerful tool for mid-IR microscopy while only requiring near-IR detection with a silicon-based camera. In this proof-of-principle implementation, we demonstrate widefield imaging over a broad wavelength range covering 3.4 to 4.3 μm and demonstrate a spatial resolution of 35 μm for images containing 650 resolved elements. Moreover, we demonstrate that our technique is suitable for acquiring microscopic images of biological tissue samples in the mid-IR. These results form a fresh perspective for potential relevance of quantum imaging techniques in the life sciences.

B. Savitzky, S. Zeltmann, L. Hughes et al.

Abstract Scanning transmission electron microscopy (STEM) allows for imaging, diffraction, and spectroscopy of materials on length scales ranging from microns to atoms. By using a high-speed, direct electron detector, it is now possible to record a full two-dimensional (2D) image of the diffracted electron beam at each probe position, typically a 2D grid of probe positions. These 4D-STEM datasets are rich in information, including signatures of the local structure, orientation, deformation, electromagnetic fields, and other sample-dependent properties. However, extracting this information requires complex analysis pipelines that include data wrangling, calibration, analysis, and visualization, all while maintaining robustness against imaging distortions and artifacts. In this paper, we present py4DSTEM, an analysis toolkit for measuring material properties from 4D-STEM datasets, written in the Python language and released with an open-source license. We describe the algorithmic steps for dataset calibration and various 4D-STEM property measurements in detail and present results from several experimental datasets. We also implement a simple and universal file format appropriate for electron microscopy data in py4DSTEM, which uses the open-source HDF5 standard. We hope this tool will benefit the research community and help improve the standards for data and computational methods in electron microscopy, and we invite the community to contribute to this ongoing project.

Ons M’Saad, J. Bewersdorf

Resolving the distribution of specific proteins at the nanoscale in the ultrastructural context of the cell is a major challenge in fluorescence microscopy. We report the discovery of a new principle for an optical contrast equivalent to electron microscopy (EM) which reveals the ultrastructural context of the cells with a conventional confocal microscope. By decrowding the intracellular space through 13 to 21-fold physical expansion while simultaneously retaining the proteins, bulk (pan) labeling of the proteome resolves local protein densities and reveals the cellular nanoarchitecture by standard light microscopy. Imaging specific proteins in the ultrastructural context largely relies on correlative light/electron microscopy, but fluorophore incompatibility and registration issues limit its use. Here the authors develop an expansion microscopy method with pan-labeling of the proteome to obtain EM-equivalent light microscopy images.

Olga Kazakova, Robert Puttock, Craig Barton et al.

Since it was first demonstrated in 1987, magnetic force microscopy (MFM) has become a truly widespread and commonly used characterization technique that has been applied to a variety of research and industrial applications. Some of the main advantages of the method includes its high spatial resolution (typically ∼50 nm), ability to work in variable temperature and applied magnetic fields, versatility, and simplicity in operation, all without almost any need for sample preparation. However, for most commercial systems, the technique has historically provided only qualitative information, and the number of available modes was typically limited, thus not reflecting the experimental demands. Additionally, the range of samples under study was largely restricted to “classic” ferromagnetic samples (typically, thin films or patterned nanostructures). Throughout this Perspective article, the recent progress and development of MFM is described, followed by a summary of the current state-of-the-art techniques and objects for study. Finally, the future of this fascinating field is discussed in the context of emerging instrumental and material developments. Aspects including quantitative MFM, the accurate interpretation of the MFM images, new instrumentation, probe-engineering alternatives, and applications of MFM to new (often interdisciplinary) areas of the materials science, physics, and biology will be discussed. We first describe the physical principles of MFM, specifically paying attention to common artifacts frequently occurring in MFM measurements; then, we present a comprehensive review of the recent developments in the MFM modes, instrumentation, and the main application areas; finally, the importance of the technique is speculated upon for emerging or anticipated to emerge fields including skyrmions, 2D-materials, and topological insulators.