Focused Ion Beam Scanning Electron Microscopy Research Articles

Effect of annealing atmosphere on MgO thin film for tunneling magnetoresistance sensor

Magnesium oxide (MgO) thin films are the most currently used as magnetic barrier shields in tunneling Magnetoresistance (TMR) sensors. In this work, MgO (50 nm) film on silicon substrates was annealed at different temperatures (250, 350, and 450 °C) and atmospheres (Argon, Nitrogen, and air). The structure, morphology, chemical composition, and thickness were investigated by using a focused-ion beam scanning electron microscope, atomic force microscopy, and X-ray photoelectron spectroscopy techniques. Increasing annealing temperature in a normal air atmosphere increases the film's thickness and roughness due to grain growth induced by Magnesium hydroxide (Mg(OH)2) formation. On the contrary, annealing in Argon does not significantly affect the thickness and roughness of the film. Furthermore, the dielectric breakdown and hardness of the film increase. The mechanism of the change of physical properties of the film due to annealing was elucidated by a qualitative model.

Three-dimensional propagation behavior of hydrogen-related intergranular cracks in high-strength martensitic steel

Using X-ray computed tomography and focused ion beam-scanning electron microscopy (FIB-SEM) serial sectioning, this study investigated the three-dimensional propagation behavior of hydrogen-related intergranular cracks in martensitic steel with a tensile strength of 1.2 GPa, focusing on segments of prior austenite grain boundaries (PAGB segments). X-ray computed tomography revealed that the crack morphology was more continuous in the hydrogen-charged specimens. Through FIB-SEM serial sectioning, we found that crack-tip blunting and ductile rupture of un-cracked ligaments were associated with specific PAGB segments in the uncharged specimen. In the case of hydrogen-related intergranular crack propagation, even very fine, low-angle PAGB segments (sub-micrometer size) can act as obstacles for crack propagation. Based on these results, we propose that the misorientation of each PAGB segment has a large influence on the local arrestability of intergranular crack propagation.

Correlative light-electron microscopy: integrating dynamics to structure

A challenge of classical electron microscopy (EM) modalities is the static and limited view they present of dynamic biological processes. Correlative light and EM (CLEM) pairs the precise imaging of the cellular location in light microscopy (LM) and EM, taking advantage of both methods. Recent advances in protein labeling, fluorescent markers, super-resolution microscopy, and EM technologies have allowed widespread application in modern biological research. Because of the wide versatility of CLEM, it is difficult to describe a single workflow. In general, samples are prepared and imaged by LM before EM preparation and imaging, with software utilized for the correlation of the two images. Fluorescent tags can help to select and localize structures for EM or add dynamics through live-cell imaging. Future developments in multimodal probes showing electron density and fluorescence activity will allow greater integration of the modalities and high-throughput workflows. Can be paired with focused ion beam-scanning EM (FIB-SEM), cryo-EM, transmission EM (TEM), and serial block-face SEM (SBF-SEM), as well as structured illumination microscopy (SIM), stimulated emission depletion (STED), and total internal reflection fluorescence (TIRF). Amenable to live-cell imaging, in part due to advances that can quickly freeze a sample for cryo-EM. Systems to pair with microscopic X-ray computed tomography to provide non-destructive forms of 3D imaging alongside high-resolution micrographs obtained by TEM and fluorescence. Sensitive enough for applications such as virus–host cell membrane interactions. Alongside other techniques, can localize the distribution of specific proteins or structures within a sample and correlate this information with the ultrastructural details provided by EM. Finding the appropriate FM and EM microscopes may be difficult and expensive. Preparing samples for both modalities requires careful planning and optimization so they are properly preserved, labeled, and processed for the chosen application. The growth of cells on the grid during the LM phase can make correlational positioning difficult. Aligning LM and EM micrographs can be challenging and time-consuming due to differences in resolution and sample shrinkage. Lower throughput and smaller region-of-interest size than traditional FM techniques due to being reliant on EM acquisition and additional sample preparation times. We thank Kit Neikirk for his thoughtful suggestions and edits to the manuscript. Funding by the UNCF/Bristol-Myers Squibb E.E. Just Faculty Fund, BWF Career Awards at the Scientific Interface Award, BWF Ad-hoc Award, National Institutes of Health (NIH) Small Research Pilot Subaward to 5R25HL106365-12 from the NIH PRIDE Program, DK020593, Vanderbilt Diabetes and Research Training Center for DRTC Alzheimer’s Disease Pilot & Feasibility Program. CZI Science Diversity Leadership grant number 2022- 253529 from the Chan Zuckerberg Initiative DAF, an advised fund of Silicon Valley Community Foundation (to A.H.). The images were arranged using BioRender and all representative images are original. The authors have no interests to declare.

Insight into mechanism of boosted oxygen reduction reaction in mixed-conducting composite cathode of solid oxide fuel cell via a novel open-source pore-scale model

Composite engineering is one of the most practical strategies for mitigating thermo-mechanical instability in state-of-the-art cobalt-based mixed ionic-electronic conducting electrodes for solid oxide cells. Nevertheless, the mechanism underlying improved performance and durability of composite electrodes is not substantially examined and understood. Pore-scale modeling can effectively bridge the gap between material property, microstructure discovery, and performance evaluation. However, most of the previous pore-scale models are built on in-house codes or commercial software that is closed-source to the public, limiting customization and community involvement. Here we report for the first time a microstructure-resolved 3D pore-scale model based on an open-source Lattice Boltzmann library, implementing a well-validated electrochemical module that considers gas, ion and electron transport, as well as electrochemical reaction at triple-phase-boundary (TPB) and double-phase-boundary (DPB). The pure La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and 50/50 vol% composite LSCF/GDC (Gd-doped ceria) cathodes are reconstructed using focused ion beam-scanning electron microscopy and then are investigated under various current densities, temperatures, oxygen concentrations, and thicknesses. Results reveal the advantages of boosted TPB density and ionic conductivity outweigh the disadvantages of lower DPB density and electronic conductivity for the composite cathode. Furthermore, the composite cathode performs better at low temperatures and low oxygen concentrations due to the presence of more macropores, the stable bulk ion conductivity of GDC, and higher TPB density. Local current distribution at active sites indicates a thickness of 20 to 40 μm is favorable for reduced overpotential and moderate reaction homogeneity.

Comparative connectomics and escape behavior in larvae of closely related Drosophila species

Evolution has generated an enormous variety of morphological, physiological, and behavioral traits in animals. How do behaviors evolve in different directions in species equipped with similar neurons and molecular components? Here we adopted a comparative approach to investigate the similarities and differences of escape behaviors in response to noxious stimuli and their underlying neural circuits between closely related drosophilid species. Drosophilids show a wide range of escape behaviors in response to noxious cues, including escape crawling, stopping, head casting, and rolling. Here we find that D.santomea, compared with its close relative D.melanogaster, shows a higher probability of rolling in response to noxious stimulation. To assess whether this behavioral difference could be attributed to differences in neural circuitry, wegenerated focused ion beam-scanning electron microscope volumes of the ventral nerve cord of D.santomea to reconstruct the downstream partners of mdIV, a nociceptive sensory neuron in D.melanogaster. Along with partner interneurons of mdVI (including Basin-2, a multisensory integration neuron necessary for rolling) previously identified in D.melanogaster, we identified two additional partners of mdVI in D.santomea. Finally, we showed that joint activation of one of the partners (Basin-1) and a common partner (Basin-2) in D.melanogaster increased rolling probability, suggesting that the high rolling probability in D.santomea is mediated by the additional activation of Basin-1 by mdIV. These results provide a plausible mechanistic explanation for how closely related species exhibit quantitative differences in the likelihood of expressing the same behavior.

Investigating structural attributes of drug encapsulated microspheres with quantitative X-ray imaging.

The intra-sphere and inter-sphere structural attributes of controlled release microsphere drug products can greatly impact their release profile and clinical performance. In developing a robust and efficient method to characterize the structure of microsphere drug products, this paper proposes X-ray microscopy (XRM) combined with artificial intelligence (AI)-based image analytics. Eight minocycline loaded poly(lactic-co-glycolic acid) (PLGA) microsphere batches were produced with controlled variations in manufacturing parameters, leading to differences in their underlying microstructures and their final release performances. A representative number of microspheres samples from each batch were imaged using high resolution, non-invasive XRM. Reconstructed images and AI-assisted segmentation were used to determine the size distribution, XRM signal intensity, and intensity variation of thousands of microspheres per sample. The signal intensity within the eight batches was nearly constant over the range of microsphere diameters, indicating high structural similarity of spheres within the same batch. Observed differences in the variation of signal intensity between different batches suggests inter-batch non-uniformity arising from differences in the underlying microstructures associated with different manufacturing parameters. These intensity variations were correlated with the structures observed from higher resolution focused ion beam scanning electron microscopy (FIB-SEM) and the in vitro release performance for the batches. The potential for this method for rapid at-line and offline product quality assessment, quality control, and quality assurance is discussed.

The Caudofoveata (Mollusca) Spicule as a Biomineralization Model: Unique Features Revealed by Combined Microscopy Methods

Caudofoveates are benthic organisms that reside in the deep waters of continental slopes in the world. They are considered to be a group that is of phylogenetic and ecological importance for the phylum Mollusca. However, they remain poorly studied. In this work, we revealed the structure of the spicules of Caudofoveatan mollusks Falcidens sp. The spicules presented a hierarchical organization pattern across different length scales. Various imaging and analytical methods related to light and electron microscopy were employed to characterize the samples. The primary imaging methods utilized included: low voltage field emission scanning electron microscopy (FEG-SEM), focused ion beam-scanning electron microscopy (FIB-SEM), high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), and electron diffraction. In addition, we performed a physicochemical analysis by electron energy loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (EDS). A crucial factor for successfully obtaining the results was the preparation of lamellae from the spicules without damaging the original structures, achieved using FIB-SEM. This allowed us to obtain diffraction patterns of significant areas of well-preserved sections (lamellae) of the spicules in specific directions and demonstrate for the first time that the bulk of these structures is organized as a single crystal of calcium carbonate aragonite. On the other hand, AFM imaging of the spicules’ dorsal surface revealed a wavy appearance, composed of myriads of small, pointed crystallites oriented along the spicules’ longer axis (i.e., the c-axis of the aragonite). The organization pattern of these small crystallites, the possible presence of twins, the relationship between confinement conditions and accessory ions in the preference for mineral polymorphs, and the single crystalline appearance of the entire spicule, along with the observation of growth lines, provide support for further studies employing Caudofoveata spicules as a model for biomineralization studies.

FIB-SEM combined with proteomics and modification omics clarified mechanisms of lipids synthesis in organelles of Chlorella pyrenoidosa cells with high CO2 concentration

In order to explain reasons why flue-gas CO2 (normally containing high CO2) enhanced carbon fixation and lipids synthesis with increased photochemical electron production in microalgae cells. Focused ion beam scanning electron microscopy (FIB-SEM) was combined with proteomics and phosphorylation modification mics to clarify mechanisms of lipids synthesis at protein and organelle levels in Chlorella pyrenoidosa cells cultivated with high CO2 concentration (15 % v/v). The volumes of chloroplast and endoplasmic reticulum in subcellular organelles increased by 47 % and 306 %, respectively, compared with the control, which improved conversion efficiency of starch grains to lipids (lipid content increased by 57 %). Proteomics and modifications omics revealed that protein translation and ribosome structure and biogenesis-related enzymes were significantly modified by phosphorylation, which regulated protein biological functions. Glycolysis, pentose phosphate pathway and other carbohydrate metabolic pathways were markedly enriched and promoted the expression of lipid synthase, which was consistent with enhanced carbon fixation in photosynthesis, expansion of subcellular organelles and improved lipids synthesis.

Microstructural Analysis of Solid Oxide Electrochemical Cells via 3D Reconstruction Using a FIB-SEM Dual Beam System

Solid oxide electrochemical cells (SOCs) have attracted increasing attention as energy conversion devices due to their high efficiency. The microstructures of SOCs play a critical role in their electrochemical performance, however, characterizing them is challenging due to their heterogeneous microstructure. This paper describes a quantitative analysis of SOC microstructures via 3D reconstruction technique using a focused ion beam-scanning electron microscope (FIB-SEM) dual beam system. The reconstructed SOC electrodes offer microstructural characteristics, including particle and pore size, tortuosity, connectivity, and triple-phase boundary (TPB) density. These in-depth analyses contribute to better understanding of the electrochemical behavior of SOCs.

Logistics of Bone Mineralization in the Chick Embryo Studied by 3D Cryo FIB-SEM Imaging.

During skeletal development, bone growth and mineralization require transport of substantial amounts of calcium, while maintaining very low concentration. How an organism overcomes this major logistical challenge remains mostly unexplained. To shed some light on the dynamics of this process, cryogenic focused ion beam-scanning electron microscopy (cryo-FIB/SEM) is used to image forming bone tissue at day 13 of a chick embryo femur. Both cells and matrix in 3D are visualized and observed as calcium-rich intracellular vesicular structures. Counting the number of these vesicles per unit volume and measuring their calcium content based on the electron back-scattering signal, the intracellular velocity at which these vesicles need to travel to transport all the calcium required for the mineral deposited in one day within the collagenous tissue can be estimated. This velocity at 0.27 µm s-1 is estimated, which is too large for a diffusion process and rather suggests active transport through the cellular network. It is concluded that calcium logistics is hierarchical and based on several transport mechanisms: first through the vasculature using calcium-binding proteins and the blood flow, then active transport over tens of micrometers through the network of osteoblasts and osteocytes, and finally diffusive transport over the last one or two microns.

Phase Segmentation of Ni/YSZ Anode for Solid Oxide Fuel Cells by Deep Learning

A deep learning network is implemented for the phase segmentation of Ni/YSZ anode of solid oxide fuel cells (SOFCs), as manual segmentation of focused ion beam-scanning electron microscopy (FIB-SEM) images is time-consuming. Segmentation is performed on two samples with different volume ratios of Ni to YSZ. The mean intersection over union (mIoU) reaches 0.9363, indicating good agreement between the predicted images and the manually segmented images. Furthermore, the impact of image augmentation on segmentation accuracy is investigated, and it is found that augmentation is necessary when the number of images in the training set is small or the training and testing sets come from different samples. Furthermore, mixing a sixth of manually segmented images from a new sample into the training set can significantly improve the accuracy of automated segmentation for the new sample. This strategy reduces the number of images requiring manual segmentation and improves processing efficiency.

Photonic Amorphous I‐WP‐Like Networks Create Angle‐Independent Colors in Sternotomis virescens Longhorn Beetles

AbstractStructural color originates from the interference of light with periodic structures that feature characteristic length scales on the order of the wavelength of visible light. Long‐range order in photonic structures usually causes iridescence, and increasing disorder renders colors angle‐independent. Random disorder distributes scattering intensity over all wavelengths, producing white in the absence of absorption. Various non‐iridescent, vivid color patterns are found in Sternotomini longhorn beetles. Herein, Sternotomis virescens is investigated, where elytral scales produce a green‐blue color pattern on otherwise black elytra. Combining focused ion beam scanning electron microscopy (FIB‐SEM) tomography, ultra‐small‐angle X‐ray scattering (USAXS), structural modeling, and full‐wave optical simulations, it is found that the color originates from amorphous photonic networks based on sub‐units resembling the I‐WP unit cell, a triply‐periodic minimal surface with body‐centered‐cubic symmetry. This work provides insights into how quasi‐order produces stable colors in S. virescens longhorn beetles, highlights the advantages of volumetric imaging using FIB‐SEM tomography of porous nanostructured materials, and raises interesting questions about the formation mechanisms of amorphous structures in vivo.

Role of Titanium in Ti/SiO2‐Supported Metallocene‐based Olefin Polymerization Catalysts. Part 2: Particle Fragmentation

AbstractA commercial SiO2 modified by the addition of a TiO2 layer on its surface and pore walls offers a support for metallocene‐based ethylene polymerization catalysts with a 35 % improved catalytic activity. The effect of such support modification on the catalyst particle fragmentation during polymerization reactions were assessed. This was performed by exposing the internal cross‐section of several SiO2 and Ti/SiO2‐based metallocene catalyst particles, polymerized at a wide range of reaction conditions, with a Focused‐Ion Beam Scanning Electron Microscope (FIB‐SEM), followed by a semi‐quantitative analysis of polymer, catalyst and macropores of each 2D image obtained. The titanation of the SiO2 lead to a support framework that fractures earlier and more efficiently. This was evidenced by the presence of several empty (polymer‐free) cracks along the support dense‐shell, found more extensively in the Ti‐modified polymerized catalyst particle, which also resulted in a more sustained polymerized particles macroporosity during the course of the reaction.

Impact of tectonic deformation on shale pore structure using adsorption experiments and 3D digital core observation: A case study of the Niutitang Formation in Northern Guizhou

Tectonic deformation has an evident impact on the pore structure of organic-rich marine shale. To study the impact of tectonic deformation on the pore structure of shale, cores were taken from different tectonic regions in the Niutitang Formation. The paleotectonic stress, pore structures, mineral composition, and geochemical parameters of the shale were determined by conducting the following tests: paleotectonic stress test, core thin-section observation, focus ion beam-scanning electron microscopy (FIB-SEM) observation, vitrinite reflectivity test, low-temperature nitrogen adsorption test, total organic carbon (TOC) test, X-ray diffraction (XRD) test, and nano-CT. The results showed that the shale in the deformed region mainly developed meso-macropores, and the pores were mainly slit-type and conical. The shale in the transition and stability regions primarily developed mesopores and micropores, which were primarily elliptical, slit-type, and columnar. The pore volumes of the shale in the deformed region were 9.54 cm3/kg and 13.9 cm3/kg higher than those in the transition and stability regions, respectively. The shale in the stability and transition regions had average microporous volumes 8.67% and 7.93% higher than that in the deformed region, respectively. The shale reservoir in the stability region developed more micropores and had a higher specific surface area and microporous volume. Furthermore, the organic matter had a greater impact on the micropores than on the meso-macropores. Thermal maturity had a greater impact on the microporous volume than on the macroporous volume. The shale pore connectivity of Well TX 1 was 86.48% and that of Well FC 1 was 22.33%. The pore connectivity of the shale in the stability region was higher than that of the shale in the deformed region. The shale samples from the deformed region had larger pore volumes and primarily developed macropores. The difference in the meso-macropores is significantly greater than the difference in the microporous volume. Hence, the geological tectonism had a greater impact on the meso-macropores than on the micropores in the shale cores.

Identification and Elemental Impurity Analysis of Heterogeneous Morphologies in Uranium Oxides Synthesized from Uranyl Fluoride Precursors.

The surface morphology characteristics of postenrichment deconversion products in the nuclear fuel cycle are important for producing nuclear fuel pellets. They also provide the first opportunity for a microstructural signature after conversion to gaseous uranium hexafluoride (UF6). This work synthesizes uranium oxides from uranyl fluoride (UO2F2) starting solutions by the wet ammonium diuranate route and a modification of the dry route. Products are reduced under a nitrogen/hydrogen atmosphere, with and without water vapor in the reducing environment. The crystal structures of the starting materials and resulting uranium oxides are characterized by powder X-ray diffraction. Scanning electron microscopy (SEM) and focused ion beam SEM with energy-dispersive X-ray spectroscopy (EDX) are used to investigate microstructural properties and quantify fluorine impurity concentrations. Heterogeneous distributions of fluorine with unique morphology characteristics were identified by backscatter electron imaging and EDX; these regions had elevated concentrations of fluorine impurities relating to the incomplete reduction of UO2F2 to UO2 and may provide a novel nuclear forensics morphology signature for nuclear fuel and U metal precursors.

Towards FIB-SEM Based Simulation of Pore-Scale Diffusion in SCR Catalyst Layers

The diffusivity in the upper Cu-Chabazite layer of a dual layer ammonia oxidation catalyst with a lower Pt layer was investigated. In a first step, the pore structure of the upper Cu-Chabazite catalyst layer was determined by Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) slice&view tomography. From the FIB-SEM data the 3D pore structure of the catalyst was reconstructed and diffusion simulations were performed on the reconstructed pore geometry, resulting in an estimated effective diffusivity of Deff/Dgas = 0.31. To validate the FIB-SEM derived estimates of the diffusivity, measurements of CO oxidation on the dual layer catalyst were performed, where the CO was oxidized in the lower Pt-layer while the upper SCR layer served as an inactive diffusion barrier. In this way, the effective diffusivity can be determined from the measured CO conversion. An effective diffusion coefficient of Deff/Dgas = 0.11 was obtained from the CO oxidation measurements, three times lower than the value obtained from the FIB-SEM data, but in line with previous literature data for the effective diffusivity in monolith washcoat layers. Additional NH3 oxidation experiments were performed on the dual layer catalyst. The results were well reproduced by a reactor model applying the effective diffusion coefficient obtained by the CO oxidation experiments. The origin of this apparent inconsistency is currently not understood and requires further investigation.

Genetically encoded barcodes for correlative volume electron microscopy

While genetically encoded reporters are common for fluorescence microscopy, equivalent multiplexable gene reporters for electron microscopy (EM) are still scarce. Here, by installing a variable number of fixation-stable metal-interacting moieties in the lumen of encapsulin nanocompartments of different sizes, we developed a suite of spherically symmetric and concentric barcodes (EMcapsulins) that are readable by standard EM techniques. Six classes of EMcapsulins could be automatically segmented and differentiated. The coding capacity was further increased by arranging several EMcapsulins into distinct patterns via a set of rigid spacers of variable length. Fluorescent EMcapsulins were expressed to monitor subcellular structures in light and EM. Neuronal expression in Drosophila and mouse brains enabled the automatic identification of genetically defined cells in EM. EMcapsulins are compatible with transmission EM, scanning EM and focused ion beam scanning EM. The expandable palette of genetically controlled EM-readable barcodes can augment anatomical EM images with multiplexed gene expression maps.

Three-dimensional pore structure characterization of cement paste by X-ray computed tomography (XCT) and focused ion beam/scanning electron microscopy (FIB/SEM)

The properties of cement paste are greatly influenced by its pore structure. The objective of this paper is to discover the three-dimensional (3-D) pore structure at different scales based on X-ray computed tomography (XCT) and focused ion beam/scanning electron microscopy (FIB/SEM). The obtained pore characteristics include porosity, pore size distribution (PSD), pore shape, orientation, connectivity and tortuosity. The measured pore shapes are far from the simplified shapes commonly used in modelling. The results show that the pore structure measured by FIB/SEM is more heterogeneous than that by XCT. Furthermore, the pore connectivity decreases when the water-cement ratio decreases, and the curing age increases or fly ash/slag is added. The connectivity reduction due to fly ash is much greater through the observation of XCT compared to FIB/SEM. The transport-related tortuosity is different from the geometric tortuosity, and the diffusional tortuosity exhibits a larger discrepancy from the hydraulic tortuosity at a lower porosity.

Abstract 1555: CDK2 inhibition & disruption of centrosome stoichiometry: a clinically tractable death program for aneuploid cancer cells

Abstract Genomic instability is a cancer hallmark. Aberrant centrosome numbers often occur in cancer and is associated with genomic instability. Mitosis with supernumerary centrosomes leads to abnormal chromosome segregation and aneuploidy in progeny cells. While many cells with abnormal chromosomes are eliminated through apoptosis, some gain a growth advantage and acquire resistance to antineoplastic agents. This aneuploidy is associated with aggressive tumor biology and unfavorable clinical outcomes. Cyclin-dependent kinase 2 (CDK2) plays a major role regulation of cell cycle progression, centrosome duplication and clustering. We previously reported that CDK2 inhibition prevented supernumerary centrosomes clustering, causing multipolar mitosis and anaphase catastrophe in lung and other aneuploid cancers. To elucidate engaged mechanisms focused ion beam scanning electron microscope (FIB-SEM) and immunofluorescent staining were each used to interrogate the ultrastructure of multipolar mitosis after CDK2 inhibition by CYC065-treatment (a CDK2/9 inhibitor). CYC065-treatment induced distinct ultrastructural changes in aneuploid lung cancer cells including formation of chromosome rings and multipolarity. As compared to vehicle controls, CYC065-treatment markedly extended the duration of chromosome rings in lung cancer cells and conferred aberrant mitosis in live cell imagining. Intriguingly, this treatment disrupted centrosome and centriole stoichiometry in cells with chromosome rings or multipolarity. These findings were confirmed using immunofluorescence assays of lung and other cancer cells having supernumerary centrosomes. To elucidate if CDK2 or CDK9 activity directly altered centriole stoichiometry, chromosome rings or multipolarity, immunofluorescent assays were performed in lung cancer cells that independently knocked down CDK2 or CDK9 using siRNAs relative to controls. Centriole stoichiometry abnormalities in cancer cells having chromosome rings or multipolarity were statistically significantly higher in CDK2 knock-down but not in CDK9 knock-down transfectants or controls. Engineered gain of CDK2 but not CDK9 expression rescued CYC065 mediated chromosome rings and multipolarity in aneuploid lung cancer cells. Taken together, this study uncovered that CDK2 inhibition disrupted centrosome stoichiometry, causing apoptotic death of aneuploid cancer cells. This is a clinically-tractable pharmacologic mechanism that conferring cancer cell death. Current work determines if similar mechanisms are engaged in vivo in syngeneic mouse lung cancer models undergoing CDK2 antagonism. Citation Format: Zibo Chen, Xi Liu, Masanori Kawakami, Xiuxia Liu, Allison Baker, Aayush Bhatawadekar, Liliya Tyutyunyk-Massey, Ethan Dmitrovsky, Kedar Narayan. CDK2 inhibition & disruption of centrosome stoichiometry: a clinically tractable death program for aneuploid cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1555.

The Study of Multi-Scale Specific Surface Area in Shale Rock with Fracture-Micropore-Nanopore

The specific surface area is an important parameter to characterize pore structure and adsorption properties, however, it is difficult to calculate accurately in shale rock due to its multiscale pore structure. In this paper, the representative 3D gray images of a microfracture sample, micropore subsample and nanopore subsample in shale rock were obtained with computed tomography (CT) scanning and focused ion beam-scanning electron microscopy (FIB-SEM) scanning. The multi-threshold segmentation algorithm with improved maximum inter-class variance method was introduced to construct the platform of multi-scale digital rock. Then, based on the fracture, micropore and nanopore digital rocks, the corresponding network models were extracted to obtain different-scale pore structures, respectively. Finally, based on the digital rock at different scales, the corresponding pore percentage, matrix percentage and specific surface area were calculated respectively. It was found that the specific surface areas of both microfractures and micropores are small, and their specific surface areas are 2~3 orders of magnitude smaller than that of nanopores, and the specific surface area of the shale formation is mainly contributed by nanopores. This paper provides an effective method to calculate the multi-scale specific surface area accurately in shale rock and has an important influence on the adsorption characteristics and swelling properties of the shale matrix.