Fracture Behavior of a 2D Imine-Based Polymer.

2D polymers have emerged as a highly promising category of nanomaterials, owing to their exceptional properties. However, the understanding of their fracture behavior and failure mechanisms remains still limited, posing challenges to their durability in practical applications. This work presents an in-depth study of the fracture kinetics of a 2D polyimine film, utilizing in situ tensile testing within a transmission electron microscope (TEM). Employing meticulously optimized transferring and patterning techniques, an elastic strain of ≈6.5% is achieved, corresponding to an elastic modulus of (8.6 ± 2.5) GPa of polycrystalline 2D polyimine thin films. In step-by-step fractures, multiple cracking events uncover the initiation and development of side crack near the main crack tip which toughens the 2D film. Simultaneously captured strain evolution through digital image correlation (DIC) analysis and observation on the crack edge confirm the occurrence of transgranular fracture patterns apart from intergranular fracture. A preferred cleavage orientation in transgranular fracture is attributed to the difference in directional flexibility along distinct orientations, which is substantiated by density functional-based tight binding (DFTB) calculations. These findings construct a comprehensive understanding of intrinsic mechanical properties and fracture behavior of an imine-linked polymer and provide insights and implications for the rational design of 2D polymers.

Mechanistic Understanding of the Underlying Energy Storage Mechanism of α-MnO2-based Pseudo-Supercapacitors.

Manganese dioxide (α-MnO2) has attracted significant research interest in supercapacitors recently. However, the reaction mechanism of α-MnO2 in supercapacitors remains unclear. Therefore, a nano-supercapacitor using Environmental transmission electron microscopy (ETEM) is conducted and investigated the reaction mechanism of α-MnO2 based on three ionic liquids (ILs). It found that in the aprotic ionic liquid (AIL) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIMOTF), α-MnO2 nanowires (NWs) undergo an oxidation reaction due to the presence of an active proton at the second position (H2) of the imidazole ring. As a result, α-MnO2 NWs undergo a phase transition and transform into Mn3O4, exhibiting pseudo-capacitive properties. Furthermore, characterization of the macroscopic α-MnO2 electrodes after cycling reveals that after the initial charging cycles, the dominant energy storage mechanism of the supercapacitor transitions from pseudo-capacitance to a dual-layer capacitance formed by the combination of Mn3O4 and unreacted α-MnO2. Simultaneously, due to the coexistence of these two energy storage mechanisms, the specific capacitance of the supercapacitor in EMIMOTF electrolyte reaches up to 80 F g-1, and the cycle number reaches as high as 1000 cycles. The results are expected to provide insights into the selection of electrolytes in supercapacitors and offer a fundamental understanding of the internal reaction mechanisms in capacitors.

Unveiling the synergistic effect of octenyl succinic anhydride and pulsed electric field on starch nanoparticles.

In this study, guinea starch nanoparticles (GSNP) were prepared by nanoprecipitation technique and modified with octenyl succinic anhydride (3 %) and pulsed electric field (1.5, 3.0, and 4.5 kV/cm). The effect of dual modification on the physicochemical, structural, morphological, thermo-pasting, and rheological properties of GSNP was investigated. The dual modification successfully incorporated octenyl groups into GSNP, as confirmed by 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The degree of substitution increased from 0.0254 to 0.0347, with particle size ranging from 241.30 to 292.50 nm and zeta potential of -23.11 to -29.98 mV. TEM micrographs revealed that all SNP samples had self-aggregated granules with a mean size below 120 nm, and XRD confirmed a V-type crystalline structure. The amylose content and water absorption capacity decreased from 34.02 % to 24.63 % and from 2.45 to 1.91 g/g, respectively, while the oil absorption capacity and relative crystallinity increased from 3.42 to 4.01 g/g and from 17.82 % to 34.76 %, with modification. The gelatinization and degradation temperature of modified samples were higher while pasting properties exhibited variation with modification. The rheological properties of modified SNP samples exhibited more pronounced shear thinning, attributed to their weaker gel structure and fluid-like gel network. Overall, results suggested that modified GSNPs have potential for stabilizing Pickering emulsion and delivery of carrier materials for active functional substances.

Chinese acupuncture: A potential treatment for autism rat model via improving synaptic function.

Purpose: Autistic symptom improvement can be observed in children treated with acupuncture, but the mechanism is still being explored. In the present study, we used scalp acupuncture to treat autism rat model, and then their improvement in the abnormal behaviors and specific mechanisms behind were revealed by detecting animal behaviors, analyzing the RNA sequencing of the prefrontal cortex (PFC), and observing the ultrastructure of PFC neurons under the transmission electron microscope. Methods: On gestational day 12.5, Wistar rats were given valproic acid (VPA) by intraperitoneal injection, and their offspring were considered to be reliable rat models of autism. They were randomized to VPA or VPA-acupuncture group (n = 8). Offspring of Wistar pregnant rats that were simultaneously injected with saline were randomly selected as the wild-type group (WT). VPA_acupuncture group rats received acupuncture intervention at 23 days of age for 4 weeks, and the other two groups followed without intervention. After the intervention, all experimental rats underwent behavioral tests. Immediately afterward, they were euthanized by cervical dislocation, and their prefrontal cortex was isolated for RNA sequencing and transmission electron microscopy. Results: The main results are as follows: 1. Animal behavioural tests: VPA group rats showed more anxiety-like behaviour and repetitive, stereotyped behaviour than WT group rats. While VPA group rats showed less spatial exploration ability, activity level, social interaction, and social novelty preference than WT group rats. It was gratifying to observe that acupuncture indeed improved these abnormal behaviors of autism rat model. 2. RNA-sequencing: The three groups of rats differed in the expression and enrichment pathways of multiple genes related to synaptic function, neural signal transduction, immune-inflammatory responses and circadian rhythm regulation. Our experiments indicated that acupuncture can alleviate the major symptoms of ASD by improving these neurological abnormalities. 3. Under the transmission electron microscopy, several lysosomes and mitochondrial structural abnormalities were observed in the prefrontal neurons of VPA group rats, which were manifested as atrophy of the mitochondrial membrane, blurring or disappearance of the mitochondrial cristae, and even vacuolization. Moreover, the number of synapses and synaptic vesicles was relatively small. Conversely, the mitochondrial structure of rats in the WT group and VPA_acupuncture was normal, and the number of synapses and synaptic vesicles was relatively large. Conclusion: Acupuncture effectively improved the abnormal behaviors of autism rat model and the ultrastructure of the PFC neurons, which might worked by improving their abnormal synaptic function, synaptic plasticity promoting neuronal signal transduction and regulating immune-inflammatory responses.

Positional differences in the micro- and ultra-structural variations of ray parenchyma cells during the transformation from sapwood to heartwood.

Ray parenchyma cells are involved in the initiation of heartwood formation. The position within a ray influences the timing of ray parenchyma cell differentiation and function; however, there is little information concerning the positional influence on the cellular changes of ray parenchyma cells from sapwood and heartwood. In this study, radial variations in morphology, size, and ultrastructure of ray parenchyma cells were studied by combined transmission electron microscopy and optical microscopy. Results showed that cellular traits of ray parenchyma cells in Populus tomentosa were all affected by both radial position in the secondary xylem and position within a ray. Specifically, radial variations in cellular traits were more evident in isolation cells, which were not adjacent to vessel elements. Both cell length and cell width/length ratio of isolation cells were bigger than contact cells, which contacted adjacent vessel elements via pits. Moreover, the secondary wall thickening and lignification of contact cells developed in the current-year xylem, much earlier than isolation cells. Secondary walls in contact cells were in a polylamellate structure with a protective layer on the inner side. No alteration in the ultrastructure of contact cells occurred in the sapwood-heartwood transition zone, except that most contact cells died. By contrast, in the transition zone, isolation cells still lived. A thin secondary wall began to deposit on the thick primary wall of isolation cells, with two isotropic layers on the inner side of the primary wall and secondary wall respectively being characteristic. Meanwhile, starch grains in isolation cells were depleted, and dark polyphenolic droplets lost their spherical shape and flowed together. Furthermore, the intercellular spaces of isolation cells became densified in the transition zone. Overall, cellular changes suggested that the positional information of ray parenchyma cells appeared to be an important factor in the transformation from sapwood to heartwood. Unlike contact cells, isolation cells were more elongated, specialized in radial transport, had a delayed formation of secondary walls, and were involved in the synthesis of heartwood substances. Our result promotes the elucidation of the involvement of xylem rays in heartwood formation.

The effect of the acceleration voltage on the quality of structure determination by 3D-electron diffraction.

Nowadays, 3D Electron Diffraction (3DED) is widely used for the structure determination of sub-micron-sized particles. In this work, we investigate the influence of the acceleration voltage on the quality of 3DED datasets acquired on BaTiO3 nanoparticles. Datasets were acquired using a wide range of beam energies, from common, high acceleration voltages (300 kV and 200 kV) to medium (120 kV and 80 kV) and low acceleration voltages (60 kV and 30 kV). It was observed that, in the integration process, Rint increases as the beam energy is reduced, which is mainly due to the increased dynamical scattering. Nevertheless, the structure was solved successfully in all cases. The structure refinement was comparable for all beam energies with small deficiencies such as negative atomic displacements for the heaviest atom in the structure, barium. Including extinction correction in the refinement noticeably improved the model for low acceleration voltages, probably due to higher beam absorption in these cases. Dynamical refinement, however, shows superior results for higher acceleration voltages, since the dynamical refinement calculations currently ignore inelastic scattering effects.

Research on the damage and wound repair of cornea by GO and ZnO.

OBJECTIVE: The widespread use of nanoparticles in recent years has increased the risk of ocular exposure. zinc oxide (ZnO) is widely used in the field of cosmetics because of its unique chemical properties. The application of graphene oxide (GO) as an emerging nanomaterial in the field of eye drops is also gradually emerging. Currently, research on ZnO and GO eye exposure mainly focuses on application or toxicity to optic nerve cells. There's less study on corneal wound healing effects. and the previous research hasn't compared ZnO and GO corneal toxicity. METHODS: We systematically established a complete chain study of in vitro and in vivo experiments and mouse corneal injury model, and comprehensively evaluated the ocular safety and toxicity of ZnO and GO. RESULTS: We found that 50 ug/mL GO and 0.5 ug/mL ZnO can reduce human corneal epithelial cells (HCEpiC) viability in a concentration-dependent manner. Short-term repeated exposure to ZnO can cause sterile inflammation of the cornea with concentration-dependence, while GO have not been significantly altered. 50 ug/mL ZnO could significantly delay the healing of corneal wounds, while GO did not change wound healing. CONCLUSION: The toxic effect of ZnO is higher than that of GO. Inflammatory signal transduction, oxidative stress and apopnano zitosis are involved in the ocular toxicity injury process of nanoparticles. Research can provide a judgement basis for people's eye health and eye protection risk control.

Effects of eczema calming lotion on the stratum corneum in atopic dermatitis: Corneodesmosin and intercellular lipid lamellae.

OBJECTIVE: Atopic dermatitis (AD) is characterized by compositional and structural changes to the skin at lesional sites. Alteration to the levels and organization of both protein and lipid components are associated with disease status and lead to impaired barrier and hydration. Corneodesmosin (CDSN) and the arrangement and length of the intercellular lipid lamellae (ICLL) are altered in disrupted skin states. The aim of this research was to profile the distribution of CDSN and the ICLL in the stratum corneum (SC) at lesional and non-lesional sites in AD-prone skin and to investigate the impact of an eczema calming lotion containing petroleum jelly, fatty acids, and colloidal oatmeal. METHODS: An IRB-approved study was conducted with participants with active AD. From a small subset of participants, tape strips were collected from lesional and non-lesional sites on the arm, prior to and after twice daily application, over 4 weeks of an eczema calming lotion containing petroleum jelly, fatty acids, and colloidal oatmeal. Fluorescent antibody staining was used to investigate the distribution of CDSN. Transmission electron microscopy (TEM) was used to characterize the ICLL. RESULTS: The distribution/coverage of CDSN was similar between lesional and non-lesional sites at baseline; application of the lotion resulted in a more defined honeycomb/peripheral distribution. Normalized ICLL (nICLL) was lower in baseline samples from lesional sites relative to non-lesional sites. Application of the lotion increased this parameter by the end of the study at all sites. CONCLUSION: The eczema calming lotion containing petroleum jelly, fatty acids and colloidal oatmeal provided changes in corneodesmosomal proteins distribution and ICLL, consistent with improvements in corneocyte maturation and improved barrier function in the skin of individuals with atopic dermatitis.

OBJECTIF: La dermatite atopique (DA) est caractérisée par des modifications de la composition et de la structure de la peau au niveau des sites lésionnels. L'altération des taux et de l'organisation des composants protéiques et lipidiques est associée au statut de la maladie, et entraîne une altération de la barrière et de l'hydratation. La cornéodesmosine (CDSN), et la disposition et la longueur des lamelles lipidiques intercellulaires (LLIC) sont altérées dans les états cutanés perturbés. L'objectif de cette étude était d'établir le profil de la distribution de la CDSN et des LLIC dans la couche cornée (CC) au niveau des sites lésionnels et non lésionnels dans la peau sujette à la DA, et d'étudier l'impact d'une lotion apaisante contre l'eczéma contenant de la vaseline, des acides gras et de l'avoine colloïdale. MÉTHODES: Une étude approuvée par un CPP a été menée auprès de participants atteints de DA active. Dans un petit sous­ensemble de participants, des bandes adhésives ont été prélevées sur des sites lésionnels et non lésionnels du bras, avant et après l'application deux fois par jour pendant 4 semaines d'une lotion apaisante contre l'eczéma contenant de la vaseline, des acides gras et de l'avoine colloïdale. Une coloration par anticorps fluorescents a été utilisée pour étudier la distribution de la CDSN. La microscopie électronique en transmission (MET) a été utilisée pour caractériser les LLIC. RÉSULTATS: La distribution/couverture de la CDSN était similaire entre les sites lésionnels et non lésionnels à l'entrée dans l'étude; l'application de la lotion a entraîné une distribution en nid d'abeille/périphérique plus définie. Le taux normalisé de LLIC (LLICn) était plus faible dans les échantillons prélevés à l'entrée dans l'étude au niveau des sites lésionnels par rapport aux sites non lésionnels. L'application de la lotion a augmenté ce paramètre à la fin de l'étude pour tous les sites. CONCLUSIONS: La lotion apaisante contre l'eczéma contenant de la vaseline, des acides gras et de l'avoine colloïdale a entraîné des changements dans la distribution des protéines cornéodesmosomales et des LLIC, ce qui correspond à des améliorations de la maturation des cornéocytes et de la fonction de barrière de la peau des personnes atteintes de dermatite atopique.

Monitoring mouse papillomavirus-associated cancer development using longitudinal Pap smear screening.

A substantial percentage of the population remains at risk for cervical cancer due to pre-existing human papillomavirus (HPV) infections, despite prophylactic vaccines. Early diagnosis and treatment are crucial for better disease outcomes. The development of new treatments heavily relies on suitable preclinical model systems. Recently, we established a mouse papillomavirus (MmuPV1) model that is relevant to HPV genital pathogenesis. In the current study, we validated the use of Papanicolaou (Pap) smears, a valuable early diagnostic tool for detecting HPV cervical cancer, to monitor disease progression in the MmuPV1 mouse model. Biweekly cervicovaginal swabs were collected from the MmuPV1-infected mice for viral DNA quantitation and cytology assessment. The Pap smear slides were evaluated for signs of epithelial cell abnormalities using the 2014 Bethesda system criteria. Tissues from the infected mice were harvested at various times post-viral infection for additional histological and virological assays. Over time, increased viral replication was consistent with higher levels of viral DNA, and it coincided with an uptick in epithelial cell abnormalities with higher severity scores noted as early as 10 weeks after viral infection. The cytological results also correlated with the histological evaluation of tissues harvested simultaneously. Both immunocompromised and immunocompetent mice with squamous cell carcinoma (SCC) cytology also developed vaginal SCCs. Notably, samples from the MmuPV1-infected mice exhibited similar cellular abnormalities compared to the corresponding human samples at similar disease stages. Hence, Pap smear screening proves to be an effective tool for the longitudinal monitoring of disease progression in the MmuPV1 mouse model. IMPORTANCE: Papanicolaou (Pap) smear has saved millions of women's lives as a valuable early screening tool for detecting human papillomavirus (HPV) cervical precancers and cancer. However, more than 200,000 women in the United States alone remain at risk for cervical cancer due to pre-existing HPV infection-induced precancers, as there are currently no effective treatments for HPV-associated precancers and cancers other than invasive procedures including a loop electrosurgical excision procedure (LEEP) to remove abnormal tissues. In the current study, we validated the use of Pap smears to monitor disease progression in our recently established mouse papillomavirus model. To the best of our knowledge, this is the first study that provides compelling evidence of applying Pap smears from cervicovaginal swabs to monitor disease progression in mice. This HPV-relevant cytology assay will enable us to develop and test novel antiviral and anti-tumor therapies using this model to eliminate HPV-associated diseases and cancers.

Biomimetic green synthesis of ZnO nanoflowers using α-amylase: from antimicrobial to toxicological evaluation.

Biologically mediated synthesis of nanomaterials has emerged as an ecologically benign and biocompatible approach. Our study explores enzymatic synthesis, utilizing α-amylase to synthesize ZnO nanoflowers (ZnO-NFs). X-ray diffraction and energy-dispersive X-ray spectroscopy revealed crystal structure and elemental composition. Dynamic light scattering analysis indicates that ZnO-NFs possess a size of 101 nm. Transmission electron microscopy showed a star-shaped morphology of ZnO-NFs with petal-like structures. ZnO-NFs exhibit potent photocatalytic properties, degrading 90% eosin, 87% methylene blue, and 81% reactive red dyes under UV light, with kinetics fitting the Langmuir-Hinshelwood pseudo-first-order rate law. The impact of pH and interfering substances on dye degradation was explored. ZnO-NFs display efficient bacteriocidal activity against different Gram-positive and negative strains, antibiofilm potential (especially with P. aeruginosa), and hemocompatibility up to 600 ppm, suggesting versatile potential in healthcare and environmental remediation applications.

Simultaneous observation of multiple interferograms with Mach-Zehnder type electron interferometer on a 1.2-MV field-emission transmission electron microscope.

We developed a Mach-Zehnder type electron interferometer (MZ-EI) that enables simultaneous observation of interferograms created at multiple output locations on a 1.2-MV field-emission transmission electron microscope. This MZ-EI is composed of two single-crystal thin films, a lens located between the single-crystal thin films, and imaging lenses. By comparing interferograms created by electron waves travelling through different beam paths, we found that the relative phase difference was caused by phase modulation passing through the single crystals and by aberrations and defocus values of the lenses. We also confirmed that the relative phase difference can be controlled using the tilted illumination method.

Origin of giant enhancement of phase contrast in electron holography of modulation-doped n-type GaN.

The electron optical phase contrast probed by electron holography at n-n+ GaN doping steps is found to exhibit a giant enhancement, in sharp contrast to the always smaller than expected phase contrast reported for p-n junctions. We unravel the physical origin of the giant enhancement by combining off-axis electron holography data with self-consistent electrostatic potential calculations. The predominant contribution to the phase contrast is shown to arise from the doping dependent screening length of the surface Fermi-level pinning, which is induced by FIB-implanted carbon point defects below the outer amorphous shell. The contribution of the built-in potential is negligible for modulation doping and only relevant for large built-in potentials at e.g. p-n junctions. This work provides a quantitative approach to so-called dead layers at TEM lamellas.

Exploring the antibiofilm and toxicity of tin oxide nanoparticles: Insights from in vitro and in vivo investigations.

BACKGROUND INFORMATION: The advancement of biological-mediated nanoscience towards higher levels and novel benchmarks is readily apparent, owing to the use of non-toxic synthesis processes and the incorporation of various additional benefits. This study aimed to synthesize stable tin oxide nanoparticles (SnO2-NPs) using S. rhizophila as a mediator. METHODS: The nanoparticles that were created by biosynthesis was examined using several analytical techniques, including Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), UV-visible (UV-vis) spectroscopy, and energy dispersive X-ray spectroscopy (EDS). RESULTS: The results obtained from the characterization techniques suggest that S. rhizophila effectively catalyzed the reduction of SnCl2 to SnO2-NPs duration of 90 min at ambient temperature with the ƛmax of 328 nm. The size of the nano crystallite formations was measured to be 23 nm. The present study investigates nanoscale applications' antibacterial efficacy against four bacterial strains, including Klebsiella Sp, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The observed zone of inhibition for the nanoparticles (NPs) varied from 10 to 25 mm. The research findings demonstrate that the nanoparticles (NPs) are effective as antibacterial, phytotoxic, and cytotoxic agents.

Association between hepatitis C virus genotype 4 and renal cell carcinoma: Molecular and virological studies.

Hepatitis C virus (HCV) is the most common infection worldwide. The correlation between HCV and renal cell carcinoma (RCC) is still mysterious. Therefore, the relationship between HCV and RCC was investigated. The study included 100 patients with RCC; 32 with HCV infection, and 68 without HCV infection. Expressions of viral proteins (NS3 and NS5A) were tested using an immune electron-microscope (IEM) and immunohistochemistry (IHC). IHC and quantitative real time-PCR investigated the presentation of human proteins TP53 and p21 genes. Transmission electron (TEM) detected viral-like particles in infected RCC tissues. The gene and protein expression of P53 was higher in HCV positive versus HCV negative patients and p21 was lower in HCV positive versus HCV negative in both tumor and normal tissue samples. Viral like particles were observed by TEM in the infected tumor and normal portion of the RCC tissues and the plasma samples. The IEM showed the depositions of NS3 and NS5A in infected renal tissues, while in noninfected samples, were not observed. The study hypothesizes that a correlation between HCV and RCC could exist through successfully detecting HCV-like particles, HCV proteins, and (p53 and p21) in RCC-infected patients.

Dual-channel neural network for instance segmentation of synapse.

Detection and segmentation of neural synapses in electron microscopy images are the committed steps for analyzing neural ultrastructure. To date, manual annotation of the structure in synapses has been the primary method, which is time-consuming and restricts the throughput of data acquisition. Recent studies have utilized a series of deformations based on a segmentation model for the detection and segmentation of transmission electron microscope images. However, the analysis of synaptic segmentation and statistics still lacks sufficient automation and high-throughput. Therefore, we developed a dual-channel neural network instance segmentation model with weighted top-down and multi-scale bottom-up schemes, which aid in accurately detecting and segmenting synaptic vesicles and their active zones within presynaptic membranes in complex environments. In addition, we proposed a masked self-supervised pre-training model based on the latest convolutional architecture to improve performance in downstream segmentation tasks. By comparing our model to other state-of-the-art methods, we determined its viability and accuracy. The applicability of our model is thoroughly demonstrated by distinct application scenarios for neurobiological research. These findings indicate that the dual-channel neural network could facilitate the analysis of synaptic structures for the advancement of biomedical research and electron microscope reconstruction techniques.

Layered structure of sialoliths compared with tonsilloliths and antroliths.

Objectives: The aim of this study was to perform a comparative analysis of the ultrastructural and chemical composition of sialoliths, tonsilloliths, and antroliths and to describe their growth pattern. Materials and Methods: We obtained 19 specimens from 18 patients and classified the specimens into three groups: sialolith (A), tonsillolith (B), and antrolith (C). The peripheral, middle, and core regions of the specimens were examined in detail by histology, micro-computed tomography (micro- CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and transmission electron microscopy (TEM). Results: In the micro-CT, group A showed alternating radiodense and radiolucent layers, while group B had a homogeneous structure. Group C specimens revealed a compact homogeneous structure. Histopathologically, group A showed a laminated, teardrop-shaped, globular structure. Group B demonstrated degrees of immature calcification of organic and inorganic materials. In group C, the lesion was not encapsulated and showed a homogeneous lamellar bone structure. SEM revealed that group A showed distinct three layers: a peripheral multilayer zone, intermediate compact zone, and the central nidus area; groups B and C did not show these layers. The main elemental components of sialoliths were O, C, Ca, N, Cu, P, Zn, Si, Zr, F, Na, and Mg. In group B, a small amount of Fe was found in the peripheral region. Group C had a shorter component list: Ca, C, O, P, F, N, Si, Na, and Mg. TEM analysis of group A showed globular structures undergoing intra-vesicular calcification. In group B, bacteria were present in the middle layer. In the outer layer of the group C antrolith, an osteoblastic rimming was observed. Conclusion: Sialoliths had distinct three layers: a peripheral multilayer zone, an intermediate compact zone and the central nidus area, while the tonsillolith and antrolith specimens lacked distinct layers and a core.

Controllable Pseudoelasticity in Metallic Nanocrystals by Grain Boundary Engineering.

Materials with pseudoelasticity can recover from large strains exceeding their elastic limits during unloading, making them promising damage-tolerant building blocks for advanced nanodevices. Nevertheless, a practical approach to realize controllable pseudoelastic behavior at nanoscale remains challenging. Here, we proposed a grain boundary (GB) engineering approach to endow metallic nanocrystals with a controllable pseudoelasticity. Both in situ nanomechanical testing and atomistic simulations demonstrate that such controllable pseudoelasticity is governed by the extension and contraction of an inherent stacking fault array at the GB. By precisely tuning GB misorientation and inclination, our simulation results reveal that metallic nanocrystals can exhibit tailored pseudoelastic performance across a broad spectrum of GBs in different face-centered cubic metals. These findings enrich our understanding of the intrinsic pseudoelasticity of GBs and provide a GB engineering approach toward metallic materials with reversible deformability.

Resolving the In Situ Three-Dimensional Structure of Fly Mechanosensory Organelles Using Serial Section Electron Tomography.

Mechanosensory organelles (MOs) are specialized subcellular entities where force-sensitive channels and supporting structures (e.g., microtubule cytoskeleton) are organized in an orderly manner. The delicate structure of MOs needs to be resolved to understand the mechanisms by which they detect forces and how they are formed. Here, we describe a protocol that allows obtaining detailed information about the nanoscopic ultrastructure of fly MOs by using serial section electron tomography (SS-ET). To preserve fine structural details, the tissues are cryo-immobilized using a high-pressure freezer followed by freeze-substitution at low temperature and embedding in resin at room temperature. Then, sample sections are prepared and used to acquire the dual-axis tilt series images, which are further processed for tomographic reconstruction. Finally, tomograms of consecutive sections are combined into a single larger volume using microtubules as fiducial markers. Using this protocol, we managed to reconstruct the sensory organelles, which provide novel molecular insights as to how fly mechanosensory organelles work and are formed. Based on our experience, we think that, with minimal modifications, this protocol can be adapted to a wide range of applications using different cell and tissue samples. Key features • Resolving the high-resolution 3D ultrastructure of subcellular organelles using serial section electron tomography (SS-ET). • Compared with single-axis tilt series, dual-axis tilt series provides a much wider coverage of Fourier space, improving resolution and features in the reconstructed tomograms. • The use of high-pressure freezing and freeze-substitution maximally preserves the fine structural details.

A simple coordinate transformation method for quickly locating the features of interest in TEM samples.

We developed a simple coordinate transformation method for quickly locating features of interest (FOIs) of samples in transmission electron microscope (TEM). The method is well suited for conducting sample searches in aberration-corrected scanning/transmission electron microscopes (S/TEM), where the survey can be very time-consuming because of the limited field of view imposed by the highly excited objective lens after fine-tuning the aberration correctors. For implementation, a digital image of the sample and the TEM holder was captured using a simple stereo-optical microscope. Naturally presented geometric patterns on the holder were referenced to construct a projective transformation between the electron and optical coordinate systems. The test results demonstrated that the method was accurate and required no electron microscope or specimen holder modifications. Additionally, it eliminated the need to mount the sample onto specific patterned TEM grids or deposit markers, resulting in universal applications for most TEM samples, holders and electron microscopes for fast FOI identification. Furthermore, we implemented the method into a Gatan script for graphical-user-interface-based step-by-step instructions. Through online communication, the script enabled real-time navigation and tracking of the motion of samples in TEM on enlarged optical images with a panoramic view.

Ultrastructural diversity in the shell of Artemia resting eggs.

The shell of Artemia resting egg, which is a delicate multilayered envelope surrounding the inside diapause embryo, plays an important role in the survival strategy of Artemia. To date, the ultrastructure of resting eggshell has been studied for only handful populations, and knowledge about the diversity of shell structure is still limited. In this paper, resting eggs from 13 Artemia populations were studied by transmission electron microscopy. Results show that the basic configuration of resting eggshell is quite conservative, but variations are not uncommon in the fine ultrastructure of each main layer of the shell (e.g., the shape and distribution of the radially oriented pores in the cortical layer; the size, number and arrangement of chambers in the alveolar layer; and the development state of outer cuticular membrane [OCM]). The ultrastructural variation of eggshell seems not to be linked with species and reproductive mode of Artemia. Resting eggs from very high habitats (4300+ m above sea level [a.s.l.]) on Qinghai-Tibet Plateau and certain tropical salterns have a hypoplastic OCM, which may be related to the adaptation to habitat conditions such as low oxygen concentration. RESEARCH HIGHLIGHTS: Comparative study on resting eggs from 13 Artemia populations reveals high diversity in the fine structure of eggshell. Resting eggs from very high (4300+ m a.s.l.) habitats commonly have a hypoplastic OCM.