Abstract Scanning transmission electron microscopy (STEM) spectrum imaging techniques, including 4D-STEM and electron energy loss spectroscopy, are widely applied to provide complex information about the local structures and properties of materials. However, the long acquisition time and size of the diffractive and spectral datasets involved in these techniques create significant challenges in preventing electron beam-induced sample changes, specimen drift, and redundant data acquisition. In this work, we present an autonomous data acquisition methodology that allows the sampling rate to be dynamically adjusted through on-the-fly assessments of incoming data. Based on programmable level of interest metrics, the method iteratively collects diffractive and spectral data while varying the local sampling rate to target the highest interest areas and avoid redundant data collection. A hardware platform built around a customized field-programmable gate array is used to implement the dynamic sampling strategy through high-speed synchronization between the scan coils, pixelated electron detector, and high-speed beam blanker. Machine learning methods are deployed to perform unsupervised clustering of acquired spectral data and inpaint the data at unsampled locations. Our development constitutes a flexible STEM platform that can be tailored for a wide range of experimental goals and enables efficient exploration and feature detection in heterogeneous materials.
Abstract Phthalates, including dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP), are plasticizers causing male reproductive toxicity. This study investigated early pubertal exposure in ninety-six immature male Swiss albino mice administered DBP or DEHP (100, 200, and 400 mg/kg) for 15 days, evaluated at 36, 45, 50, and 70 days to assess both exposure effects and recovery. Light microscopy of Hematoxylin and Eosin-stained sperm smears and transmission electron microscopy (TEM), alongside immunohistochemical investigations for inhibin-α, calretinin, and peroxisome proliferator-activated receptor gamma (PPAR-γ), were utilized. Exposure induced severe, dose-dependent toxicity, causing complete sperm absence at 36 days, followed by reduced viability (∼20%) and teratozoospermia (>80%). TEM revealed extensive ultrastructural damage; mitochondrial degeneration reached 37% (DBP-400) and 47.9% (DEHP-400), while Sertoli cell vacuolization averaged ∼8 and ∼5 vacuoles/cell in high-dose groups. Concurrently, disrupted lipid homeostasis was evidenced by peroxisome proliferation and increased Leydig lipid area fraction, exceeding 50% in the DBP-400 group by 50 days. Recovery at 70 days was dose-dependent, occurring primarily in low-dose groups following treatment withdrawal. Immunohistochemical investigations demonstrated decreased inhibin-α and calretinin expression, alongside increased PPAR-γ immunoreactivity. Early-puberty phthalate exposure was associated with mitochondrial injury, altered PPAR-γ expression, disrupted lipid homeostasis, and incomplete recovery of testicular alterations at higher doses.
Abstract Menopause-associated hypoestrogenism promotes structural and functional alterations in skeletal muscle, contributing to muscle structural adaptation and neuromuscular impairment. Whole-body vibration (WBV) has emerged as a potential non-pharmacological intervention to attenuate these alterations; however, its effects on skeletal muscle fibers and neuromuscular junctions (NMJs) under hypoestrogenic conditions remain incompletely understood. This study investigated the effects of WBV on the extensor digitorum longus (EDL) muscle of oophorectomized Wistar rats. Sixty-four female Wistar rats were allocated into four experimental groups: SHAM-SED, SHAM-WBV, OOPHX-SED, and OOPHX-WBV. Sixty days after surgery, animals assigned to WBV groups were subjected to mechanical vibration (60 Hz, 2 mm, 10 min/session, three times weekly) for 8 weeks. Morphological, morphometric, ultrastructural, and NMJ analyses were performed in the EDL muscle. Oophorectomy promoted significant skeletal muscle remodeling, characterized by reduced muscle fiber cross-sectional area, altered fiber-type distribution, reduced NMJ dimensions, and decreased myonuclear parameters. WBV treatment induced additional structural adaptations, including increased NMJ area and altered sarcomere organization. Ultrastructural analysis demonstrated increased Z-line dissolution in WBV-treated animals. Although WBV promoted neuromuscular remodeling, it did not prevent the reduction in muscle fiber size associated with oophorectomy. These findings demonstrate that hypoestrogenism induces significant structural alterations in skeletal muscle and NMJs, while WBV promotes selective neuromuscular and ultrastructural reorganization in oophorectomized animals. The results indicate that WBV induces selective structural and neuromuscular remodeling, although its effects on muscle fiber preservation appear limited under hypoestrogenic conditions.
Abstract Orientation mapping techniques such as electron backscatter diffraction (EBSD) and automated crystal orientation mapping technique (ACOM-TEM) rely on dedicated quality metrics to assess the reliability of crystallographic indexing at each pixel. The eCHORD technique (electron CHanneling ORientation Determination), which recovers crystalline orientations in a standard scanning electron microscope by matching experimental backscattered electrons intensity profiles against a database of theoretical profiles, currently lacks such a robust confidence indicator. This work introduces a confidence index for eCHORD orientation mapping based on the windowed normalized cross-correlation index (wNCC) between experimental and theoretical profiles evaluated over sliding angular windows. Unlike the Euclidean distance used in the standard indexing step, the wNCC is sensitive to local profile discrepancies and provides a per-pixel reliability estimate directly analogous to the confidence index in EBSD or the reliability index in ACOM-TEM. The index was validated on three materials—an aluminum alloy, a copper microelectronic pad, and an α-titanium sample—and across several acquisition and indexing conditions. It successfully identifies unreliable pixels at grain boundaries, surface defects, and within poorly indexed grains, and constitutes an effective confidence metric within the eCHORD framework.
