Characterization Of Three-dimensional Structure Research Articles

Three-dimensional structural tomography and thermal characterization of the kidney stones and gallstones to know the temperature disintegration

The present study aimed to carry out a structural and thermal characterization of kidney and gallstones to reinforce knowledge aimed at their possible reduction or disintegration. Densities of 36 body stones at different dimensions, obtained by assessments of mass and volume, and structural features of the stones identified by 3D tomographic analysis. The density of kidney stones was greater than that of gallstones, at 0.0025 gr/cm3 > 0.0020 gr/cm3. DTA and TG curves of kidney stones showed minimal structural changes after 200 °C, with initial mass loss and release of carbon dioxide at 458 °C resulting in 66 % mass loss and the transformation of C2H2CaO5. Gallstones are composed mainly of cholesterol (C27H46O). Cholesterol gallstones have a relatively low density and are susceptible to potentially disintegrating within the human body. Kidney stones require high temperatures above 400 °C for their size reduction, which is why partial intracorporeal thermal disintegration may not be feasible.

The effects of three-dimensional bedding on shale fracture behavior: Insights from experimental and numerical investigations

The three-dimensional (3D) structural characteristics of the bedding planes exhibit strong anisotropy in the fracture behavior of shale. Previous studies on the anisotropy of shale fracture characteristics focused on 2D bedding effects, while 3D bedding effects that comprehensively consider bedding angles α and β have been rarely investigated. Therefore, the fracture behavior of shale with 3D bedding planes was studied based on laboratory experiments and numerical simulation. The results indicated that the apparent fracture toughness (AFT) of shale decreased with increasing bedding angle α. The fracture toughness of shale with a bedding angle of α = 0° was 2.26 MPa·m0.5 (β = 0°). However, when the loading angle α increased to 90°, the AFT decreased by 67.70 %. The increase in bedding angle β could improve the AFT significantly, and the higher the loading angle α, the more significant the improvement. The improvement amplitude at α = 90° reached 156.65 %. Due to the enhanced ability of shale to resist crack propagation by the bedding angle β, the trend of dissipation energy under the influence of 3D bedding effects was consistent with the AFT, and the two were positively correlated. Affected by the 3D bedding effect, three typical failure modes of shale have been observed: bedding failure, matrix failure, and mixed failure mode. Based on the calculation of the fractal dimension of the fracture surface, the roughness of the fracture surface under different failure modes was mixed failure > matrix failure > bedding failure. In addition, a 3D numerical model was established based on the DEM method, and the influence of new cracks on fracture toughness was considered after verifying the effectiveness of the numerical model. The length of newly formed cracks at the tip of shale prefabricated cracks exceeded 4.0 mm under critical load. Ignoring the length of new cracks will underestimate the fracture toughness of shale by about 30 %. Finally, the influence of 3D bedding planes on the crack propagation path was discussed.

The effects of three-dimensional bedding on shale fracture behavior: Insights from experimental and numerical investigations

The three-dimensional (3D) structural characteristics of the bedding planes exhibit strong anisotropy in the fracture behavior of shale. Previous studies on the anisotropy of shale fracture characteristics focused on 2D bedding effects, while 3D bedding effects that comprehensively consider bedding angles α and β have been rarely investigated. Therefore, the fracture behavior of shale with 3D bedding planes was studied based on laboratory experiments and numerical simulation. The results indicated that the apparent fracture toughness (AFT) of shale decreased with increasing bedding angle α. The fracture toughness of shale with a bedding angle of α = 0° was 2.26 MPa·m0.5 (β = 0°). However, when the loading angle α increased to 90°, the AFT decreased by 67.70 %. The increase in bedding angle β could improve the AFT significantly, and the higher the loading angle α, the more significant the improvement. The improvement amplitude at α = 90° reached 156.65 %. Due to the enhanced ability of shale to resist crack propagation by the bedding angle β, the trend of dissipation energy under the influence of 3D bedding effects was consistent with the AFT, and the two were positively correlated. Affected by the 3D bedding effect, three typical failure modes of shale have been observed: bedding failure, matrix failure, and mixed failure mode. Based on the calculation of the fractal dimension of the fracture surface, the roughness of the fracture surface under different failure modes was mixed failure > matrix failure > bedding failure. In addition, a 3D numerical model was established based on the DEM method, and the influence of new cracks on fracture toughness was considered after verifying the effectiveness of the numerical model. The length of newly formed cracks at the tip of shale prefabricated cracks exceeded 4.0 mm under critical load. Ignoring the length of new cracks will underestimate the fracture toughness of shale by about 30 %. Finally, the influence of 3D bedding planes on the crack propagation path was discussed.

Recent Advances in Conductive Polymers-Based Electrochemical Sensors for Biomedical and Environmental Applications.

Electrochemical sensors play a pivotal role in various fields, such as biomedicine and environmental detection, due to their exceptional sensitivity, selectivity, stability, rapid response time, user-friendly operation, and ease of miniaturization and integration. In addition to the research conducted in the application field, significant focus is placed on the selection and optimization of electrode interface materials for electrochemical sensors. The detection performance of these sensors can be significantly enhanced by modifying the interface of either inorganic metal electrodes or printed electrodes. Among numerous available modification materials, conductive polymers (CPs) possess not only excellent conductivity exhibited by inorganic conductors but also unique three-dimensional structural characteristics inherent to polymers. This distinctive combination allows CPs to increase active sites during the detection process while providing channels for rapid ion transmission and facilitating efficient electron transfer during reaction processes. This review article primarily highlights recent research progress concerning CPs as an ideal choice for modifying electrochemical sensors owing to their remarkable features that make them well-suited for biomedical and environmental applications.

Experimental and numerical investigation of the effects of porous bleed systems on a model scramjet inlet under high backpressure conditions

In this study, we conducted experimental and numerical investigations to assess the effects of backpressure and configurations of porous bleeds on a scramjet inlet's performance at Mach 5. Experiments in a high-enthalpy wind tunnel, using a backpressure controller and a porous bleed with 1 mm holes and 10 mm lateral spacing, were paired with Reynolds-averaged Navier-Stokes simulations to explore the mitigation of flow separation and the prevention of inlet unstart under various backpressure conditions. The simulations provided insights into how backpressure levels and porous bleed geometries impact internal flow structures, as well as the critical backpressure ratio at which inlet unstart occurs. Additional simulations varied the bleed system's hole diameter and spacing, identifying configurations that optimize aerodynamic performance by enhancing total pressure recovery and Mach number at the isolator exit, while reducing bleed mass flow rates. The study also quantified the impact of these configurations on engine thrust, determining that certain bleed system designs significantly improve thrust by efficiently suppressing the interaction between the core flow and corner recirculation zones. This study examined the internal three-dimensional flow structure characteristics under high back pressure and provided insights into porous bleed configuration capable of efficiently suppressing inlet unstart.

Precipitation Characteristics at Different Developmental Stages of the Tibetan Plateau Vortex in July 2021 Based on GPM-DPR Data

The Tibetan Plateau vortex (TPV), as an α-scale mesoscale weather system, often brings severe weather conditions like torrential rain and severe convective storms. Based on the detections from the Global Precipitation Measurement (GPM) Core Observatory’s Dual-frequency Precipitation Radar (DPR) and the FY-4A satellite’s Advanced Geostationary Radiation Imager (AGRI), combined with ERA5 reanalysis data, the precipitation characteristics of a TPV moving eastward during 8–13 July 2021 at different developmental stages are explored in this study. It was clear that the near-surface precipitation rate of the TPV during the initial stage at the eastern Tibetan Plateau (TP) was below 1 mm·h−1, implying overall weak precipitation dominated by stratiform clouds. After moving out of the TP, the radar reflectivity factor (Ze), precipitation rate, and normalized intercept parameter (dBNw) significantly increased, while the proportion of convective clouds gradually rose. Following the TPV movement, the distribution range and vertical thickness of Ze, mass-weighted mean diameter (Dm), and dBNw tended to increase. The high-frequency region of Ze appeared at 15–20 dBZ, while Dm and dBNw occurred at around 1 mm and 33 mm−1·m−3, respectively. Near the melting layer, Ze was characterized by a significant increase due to the aggregation and melting of ice crystals. The precipitation rate of convective clouds was generally greater than that of stratiform clouds, whilst both of them increased during the movement of the TPV. Particularly, at 01:00 on 12 July, there was a significant increase in the precipitation rate and Dm of convective clouds, while dBNw noticeably decreased. These findings could provide valuable insights into the three-dimensional structure and microphysical characteristics of the precipitation during the movement of the TPV, contributing to a better understanding of cloud precipitation mechanisms.

In-situ rapid nondestructive characterization of multiple irregular three-dimensional grain boundary structures and electrical properties by nanorobot with SEM in ZnO

To address the problem of spatial quantification of irregular grain boundaries, a unique approach for the nondestructive characterization of multiple irregular three-dimensional grain boundaries is proposed using nanorobots with scanning electron microscopy (SEM) to accomplish in-situ rapid synchronized quantification of structures and electrical properties. By constructing a three-dimensional trigonometric geometric mapping relationship, multiple irregular three-dimensional grain boundary structures and electrical properties can be rapidly quantified. Experimental results demonstrate that it is feasible to accomplish in-situ rapid nondestructive characterizations. The two-dimensional profile shapes of the targeted grain boundaries at each layer exhibit irregular and non-uniform features in the Y-Z plane. The hypotenuse length between the virtual space tilting lines presents a three-dimensional characteristic in the X-Z plane. The spatial tilt angle of the virtual space tilting line can be calculated using the right-triangle relation. The unequal numbers of grains along the same tilted hypotenuse direction with equal lengths directly illustrate the existence of irregular and nonlinear grain boundaries in bulk ZnO ceramics. The relatively uniform spatial sizes of the grain boundary illustrate the coupled spatial characteristics existing in the irregular micro-structures. The relatively uniform equivalent circuit fitting parameters confirm the existence of relatively uniform doping components in bulk ZnO ceramics. Furthermore, this method provides a unique approach for the rapid nondestructive quantitative analysis of multiple three-dimensional irregular grain boundaries in bulk polycrystalline materials.

Application of Femtosecond Laser Processing Method in the Sustainable Conservation of Stone Cultural Relics: An Example of Green Schist in Wudang Mountain, China

The ancient building complex in Wudang Mountain, China, is known as the “Museum of Ancient Chinese Architectural Accomplishments”. However, the valuable stone components are preserved in open or semi-open environments and environmental factors such as rain seriously threaten its sustainable conservation. In this context, a femtosecond laser processing method has been demonstrated to be able to prepare hierarchical micro-nano structures on the stone surface to regulate its wettability, achieving the purpose of sustainable conservation. In this paper, the processing mechanism and performance of the femtosecond laser on green schist, a local stone material in the Wudang Mountain, are systematically investigated. It is found that green schist, as a typical non-homogeneous material, exhibits significant differences in its absorption of femtosecond laser with different compositions. Among them, quartz, chlorite, and muscovite are the three main compositions, and they are mainly characterized by cold ablation, thermal melting, and expansion under the irradiation of the femtosecond laser (238 fs, 100 kHz, 40 μJ, 33 μm, 500–40,000 pulses), respectively, and it is difficult to achieve a uniform and stable surface structure. Based on this, we prepared grooves with a spacing of 100–400 μm by scanning the femtosecond laser. Through the characterization of surface morphology, elemental composition, and three-dimensional structure, the processing mechanism of the hierarchical micro-nano structures of green schist under the irradiation of the femtosecond laser is comprehensively revealed. Finally, the wettability modulation result of water contact angle up to 147° is achieved by processing the grooves with an optimal spacing of 400 μm. The results of this research are of guiding significance for the sustainable conservation of ancient buildings and cultural relics.

Abstract 7013: Methyl-Micro-C: simultaneous high-resolution characterization of three-dimensional chromatin structure and the DNA methylome

Abstract Understanding cancer biology allows for the determination of patient prognosis through biomarkers and predicting treatment sensitivity. For many cancer types, genetic changes have been largely characterized, but the contributions of epigenetic changes, which are also implicated in tumorigenesis, are not yet well understood. Three-dimensional chromatin architecture changes occur throughout tumor development, changing the states and interactions between cis-regulatory elements, overall inducing gene dysregulation. Chromatin structure changes have previously been interrogated using Hi-C, a technique which utilizes restriction enzyme-mediated digestion of chromatin. Although this method is useful, it cannot detect chromatin states of regulatory elements with high sensitivity and resolution due to the use of restriction enzymes that give multi-nucleosome-sized fragments. Micro-C instead uses MNase that preferentially digests accessible regulatory elements, resulting in mono, di, and tri-nucleosome fragments, providing higher-resolution chromatin interaction data, indirectly determining which regulatory elements are active and in proximity to one another. However, spatial proximity of genomic regions are only a piece of the chromatin structure epigenetic story. Partially methylated domains, which are gained or altered throughout tumor development, are reported to co-localize with topologically associating domains, suggesting that they can contribute to chromatin structure alterations. Whole methylome sequencing techniques can be used to determine methylation states of these domains and regulatory regions. Recently, enzyme-mediated methylation sequencing has been shown to induce less DNA damage than the canonical whole-genome bisulfite sequencing, providing a more accurate and comprehensive picture of the DNA methylome. Although DNA methylome data alone can provide information about epigenetic status within genomic regions, overlaying chromatin structure changes at these locations can further corroborate findings. In this way, chromatin structure and DNA methylome data together can provide a more complete picture of cancer epigenetics. However, it is very expensive to sequence at the depth necessary to gain useful information. To address this issue, we developed a technique called Methyl-Micro-C to simultaneously interrogate the DNA methylome while observing chromatin structure in the same sample. Methyl-Micro-C integrates the higher resolution Micro-C method and more comprehensive enzyme-mediated methylation sequencing method together to investigate both the chromatin interactions as well as DNA methylation patterns for the same sample simultaneously. Here, we use Methyl-Micro-C with prostate cancer cells to characterize 3D epigenomic mechanisms that drive prostate carcinogenesis. Citation Format: Claire Stevens, Leonardo Gonzalez-Smith, Huan Cao, Suhn K. Rhie. Methyl-Micro-C: simultaneous high-resolution characterization of three-dimensional chromatin structure and the DNA methylome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7013.

Role of three-dimensional vortex motions on horizontal eddies in an open-channel cavity

AbstractLateral cavities are a popular object of study in hydraulic research as they are widely found in rivers and hydraulic facilities and significantly impact flow patterns, sediment transport, and water quality in aquatic ecosystems. While the effects of open-channel cavities on various aspects including characteristics of three-dimensional structures have been extensively studied, the role of vertical flow structures in the cavity has not been focused on. This study examines the relationship between the shallowness parameter and the three-dimensional flow effects on the dynamics of an open-channel lateral cavity flow with horizontal vortex motion, comparing the conventional two-dimensional model (2DC), advanced depth-integrated models including general bottom velocity calculation method (GBVC) with the ability to consider vertical flow structures, simplified bottom velocity calculation method with the shallow water assumption (SBVC), a three-dimensional model (3DC), and experimental data. The comparison results demonstrate that the three-dimensional flow effect significantly impacts the velocity distribution and vortex evolution in the cavity. The GBVC model demonstrates a good agreement with the flow patterns by the 3DC model and experimental results in the cavity, whereas the 2DC and SBVC models are unsuitable for deep-water conditions.

The first complete genome sequence and genetic evolution analysis of bovine norovirus in Xinjiang, China

Abstract Introduction Viruses are among the main pathogens causing diarrhoea in calves. The current study found that bovine norovirus (BNoV) is one of the principal viruses causing diarrhoea in calves in Xinjiang, China. Material and Methods A total of 974 calf faecal samples from six regions in Xinjiang were tested for BNoV using reverse-transcriptase PCR. The genomic characteristics of BNoV and the genetic evolution of the VP1 gene, protein three-dimensional structure characteristics and amino acid variation were analysed using bioinformatics methods. Results Epidemiological survey results showed that the infection rate of BNoV was 19.82%, and all samples tested positive in five regions. The results of the genetic evolution analysis showed that BNoV strains from Tacheng of northern Xinjiang and Kashgar of southern Xinjiang both belonged to the GIII.2 genotype of BNoV but were not on the same cluster of evolutionary branches. Additionally, the amino acid variation of the VP1 protein was not observed to significantly affect its spatial structure. Conclusion This study is the first to report the genetic characteristics of the BNoV complete genome sequence in Xinjiang and provides a scientific basis for BNoV vaccine development and pathogenesis research.

Three-dimensional temperature field inversion in the northern South China Sea

A Swin Transformer oceanic three-dimensional temperature field inversion model is established for the northern South China Sea and its surrounding waters based on satellite observation data and ocean reanalysis data from 1993 to 2018. The inversion results are tested using Argo observation data. The root-mean-square errors of the monthly average temperature fields for 2017 and 2018 are 0.10 to 1.98°C and 0.11 to 1.92°C, respectively, with the maximum values mainly located near the mixing layer. The temperature inversion root-mean-square errors are generally less than 1 °C. Additionally, this article analyzes the three-dimensional structural characteristics and evolution process of a typical anticyclone eddy in the study area. The results show that the inversion results can clearly demonstrate the three-dimensional structure of the eddy and continuously and completely reproduce the process of eddy persistence and movement.

Three-dimensional fine crust-mantle structure imaging and structural characteristics of Bohai Sea

This study used the consistency-constrained double-difference tomography method to invert 3D fine structure models of Vp, Vs, Vp/Vs at depths above 60 km, and precise relocation parameters of earthquakes in the Bohai Sea. According to the results, the velocity structures of P-wave and S-wave in the Bohai Sea area were highly similar and demonstrated noticeable lateral non-uniformity. The crust beneath the Tanlu Fault displayed a clear stratification structure, with a continuous velocity transition in the middle of the crust. The intricate crustal structure beneath the Zhangpeng Fault displayed high-velocity bodies in the crust and low-velocity anomalous zones connected to the top of the mantle in the lower section of the crust. The structural pattern in the deep crust of the Bohai Sea controls the occurrence characteristics of the Zhangpeng Fault and the Tanlu Fault. The earthquakes in the Bohai Sea area were concentrated mainly in the southern part near the Zhangpeng Fault. There is a good correspondence between the relocated earthquakes and velocity structure. There are many significant differences in crustal structure between the north and south of the Bohai Strait, and there are obvious velocity anomalies in the middle and upper crust. The distribution shape of high Vp/Vs value indicates that mantle material migration has occurred at the bottom of the crust. This paper provided important reference for further research on the relationship between deep tectonic features and tectonic activity in the North China Craton.

Laser direct writing of efficient 3D TiO2 nano-photocatalysts

The increasing demand for functional nanodevices in sustainable energy applications necessitates the development of innovative approaches. In this study, we present the fabrication and characterization of three-dimensional (3D) structures coated with titanium dioxide (TiO2) nanorods (NRs). These novel devices are created through the integration of four distinct techniques, multi-photon lithography, post-thermal treatment, pulsed laser deposition, and an aqueous chemical growth, enabling their unique properties and functionalities in photocatalysis. The photocatalytic performance of the 3D devices is evaluated through the degradation of organic pollutants, such as methylene blue and stearic acid, showcasing their efficiency in reducing pollutant concentrations. The devices demonstrate a remarkable decomposition coefficient (k=0.059min−1), highlighting their enhanced photocatalytic efficiency. Additionally, we propose a rapid fabrication technique using 3D holographic printing to create large-area TiO2-coated micro-structured photocatalytic devices at the mesoscale regime. This approach increases the active surface area, further enhancing the devices’ photocatalytic capabilities. By combining additive micro-manufacturing, TiO2 NR coating, and holographic printing, our work introduces a promising avenue for the development of advanced nanodevices with superior photocatalytic performance in sustainable energy applications.

Probabilistic aeroelastic analysis of high-fidelity composite aircraft wing with manufacturing variability

Safety margins of aerospace structures can be improved through altering the laminate parameters of composite materials to increase flutter and divergence velocities. Existing work demonstrates the impact of material uncertainties on low-fidelity structural models that are not sufficient to represent realistic aircraft designs. A gap exists in quantifying laminate parameter uncertainties on aeroelasticity for high-fidelity three-dimensional composite structures in realistic tailored designs. This paper puts forward an efficient methodology for uncertainty quantification on the aeroelastic characteristics of three-dimensional composite structures using FE-based parametric composite models and advanced Kriging surrogate models. The methodology is tested on both low and high fidelity case studies to represent the composite wing structure. Similarities between the case studies are observed in the coefficient of variance of all hard flutter modes being within 0.15-1.4% of each other. The difference was found for divergence and soft flutter velocities where the coefficient of variance could be over ten times higher in the high fidelity case. Global sensitivity results revealed similar physical behavior cases can be produced from both studies at early design stages.

Three-dimensional structural characterization and mechanical properties of bamboo parenchyma tissue

Bamboo is predominantly composed of parenchyma and fibers, with parenchyma constituting approximately 52% of the bamboo culm wall. The bamboo fibers function as the primary load-bearing elements, its structure and performance have been studied in detail. However, investigations concerning the structure and mechanical properties of parenchyma tissue remain limited. Consequently, this study focuses on the comprehensive characterization of the three-dimensional (3D) structure of bamboo parenchyma. Additionally, the study encompasses the evaluation of tensile and compressive properties of parenchyma tissue, along with an analysis and discourse on failure mechanisms. Parenchyma cells can be categorized into two types: long cells, accounting for approximately 89.37%, and short cells. The measured tensile strength and elastic modulus of the parenchyma tissue are 48.81 MPa and 706.48 MPa, respectively. The propagation of cracks leading to tensile failure predominantly occurs along the middle lamella, accompanied by partial penetration through cell walls. Concerning parenchyma tissue compression, three discernible stages can be identified: the elastic stage, plateau stage, and densification stage. The axial load-bearing capacity of parenchyma tissue exceeds that of the tangential and radial orientations. Axial compressive strength and elastic modulus of the parenchyma are measured at 18.82 MPa and 5.24 GPa, respectively. Compression failure modes in parenchyma tissue encompass compression bending and cell fracture, shear failure of the middle lamella, and detachment and debonding of the cell wall. The comprehensive structural and mechanical parameters derived from this investigation provide valuable insights for the development of numerical models and understanding the various mechanical properties of bamboo.

Numerical Simulation of 3D Flow Structure and Turbulence Characteristics near Permeable Spur Dike in Channels with Varying Sinuosities

Owing to the different degrees of bending in rivers in nature, it is difficult to conduct experiments in situ. In this study, the renormalization group (RNG) k-ε turbulence model in ANSYS Fluent was used to analyze the three-dimensional flow structure and turbulence characteristics near a spur dike and to evaluate the variation trend of flow in rivers with different degrees of bending. The results show that in channels with different curvatures, the vortex appears between the spur dikes and is disturbed by the permeable hole, and the backflow area moves downstream. The strength of secondary flow (SSF) fluctuates greatly in the vicinity of the spur dike and the downstream region, and the peak value appears 3.22 m (21.5 times L) away from the inlet of the bend. The SSF increases as the bend curvature increases. The SSF displays similar variation trends in the three kinds of bends. The peak value of normalized turbulent kinetic energy (NTKE) appears 3.14 m away from the entrance of the bend, the NTKE is the largest in the 45° bend and the smallest in the 180° bend, and it decreases only at distances of 3.25–4.19 m away from the entrance of the bend as the bend curvature increases.

Research on the evolutionary history of the morphological structure of cotton seeds: a new perspective based on high-resolution micro-CT technology.

Cotton (Gossypium hirsutum L.) seed morphological structure has a significant impact on the germination, growth and quality formation. However, the wide variation of cotton seed morphology makes it difficult to achieve quantitative analysis using traditional phenotype acquisition methods. In recent years, the application of micro-CT technology has made it possible to analyze the three-dimensional morphological structure of seeds, and has shown technical advantages in accurate identification of seed phenotypes. In this study, we reconstructed the seed morphological structure based on micro-CT technology, deep neural network Unet-3D model, and threshold segmentation methods, extracted 11 basics phenotypes traits, and constructed three new phenotype traits of seed coat specific surface area, seed coat thickness ratio and seed density ratio, using 102 cotton germplasm resources with clear year characteristics. Our results show that there is a significant positive correlation (P< 0.001) between the cotton seed size and that of the seed kernel and seed coat volume, with correlation coefficients ranging from 0.51 to 0.92, while the cavity volume has a lower correlation with other phenotype indicators (r<0.37, P< 0.001). Comparison of changes in Chinese self-bred varieties showed that seed volume, seed surface area, seed coat volume, cavity volume and seed coat thickness increased by 11.39%, 10.10%, 18.67%, 115.76% and 7.95%, respectively, while seed kernel volume, seed kernel surface area and seed fullness decreased by 7.01%, 0.72% and 16.25%. Combining with the results of cluster analysis, during the hundred-year cultivation history of cotton in China, it showed that the specific surface area of seed structure decreased by 1.27%, the relative thickness of seed coat increased by 8.70%, and the compactness of seed structure increased by 50.17%. Furthermore, the new indicators developed based on micro-CT technology can fully consider the three-dimensional morphological structure and cross-sectional characteristics among the indicators and reflect technical advantages. In this study, we constructed a microscopic phenotype research system for cotton seeds, revealing the morphological changes of cotton seeds with the year in China and providing a theoretical basis for the quantitative analysis and evaluation of seed morphology.

Three-dimensional visualization structural characteristics and performance of discontinuous coarse fiber bamboo nodes

Bamboo nodes play a crucial role in ensuring the strength of hollow-structured bamboo, but compared with the internodes of unidirectional fiber structures, their structural which has discontinuous fiber characteristics are less understood. Here, we studied the structure-performance-fracture relationship between the internodes and nodes of bamboo. We examined the spatial heterogeneity of bamboo nodes through a three-dimensional reconstruction imaging strategy. We combined pendulum impact and high-speed photography with scanning electron microscopy to explore the regular fracture mechanism of bamboo nodes and compare it with internodes. An increase in slightly convex and ridged bamboo nodes occurred because there were thicker fiber bundles at the bamboo nodes. This caused fiber bundles to be deflected towards both sides instead of following a straight line. The bamboo nodes were more prone to regular fracture due to the discontinuous characteristics of fibers at bamboo nodes and the large void defects in the cross-section of node ridges, which destroyed the longitudinal continuity of thin-walled cells and fibers. In addition, under an impact, the main fracture mode of bamboo nodes was surface-penetrating fracture, and the main fracture modes between nodes included fiber pulling, fiber pulling out, and fiber bridging. This study provides a more in-depth understanding of bamboo and practical guidance for its development and applications in engineering structure.

Three-Dimensional Pore Structure Characterization of Bituminous Coal and Its Relationship with Adsorption Capacity.

Bituminous coal reservoirs exhibit pronounced heterogeneity, which significantly impedes the production capacity of coalbed methane. Therefore, obtaining a thorough comprehension of the pore characteristics of bituminous coal reservoirs is essential for understanding the dynamic interaction between gas and coal, as well as ensuring the safety and efficiency of coal mine production. In this study, we conducted a comprehensive analysis of the pore structure and surface roughness of six bituminous coal samples (1.19% < Ro,max < 2.55%) using various atomic force microscopy (AFM) techniques. Firstly, we compared the microscopic morphology obtained through low-pressure nitrogen gas adsorption (LP-N2-GA) and AFM. It was observed that LP-N2-GA provides a comprehensive depiction of various pore structures, whereas AFM only allows the observation of V-shaped and wedge-shaped pores. Subsequently, the pore structure analysis of the coal samples was performed using Threshold and Chen's algorithms at ×200 and ×4000 magnifications. Our findings indicate that Chen's algorithm enables the observation of a greater number of pores compared to the Threshold algorithm. Moreover, the porosity obtained through the 3D algorithm is more accurate and closely aligns with the results from LP-N2-GA analysis. Regarding the effect of magnification, it was found that ×4000 magnification yielded a higher number of pores compared to ×200 magnification. The roughness values (Rq and Ra) obtained at ×200 magnification were 5-14 times greater than those at ×4000 magnification. Interestingly, despite the differences in magnification, the difference in porosity between ×200 and ×4000 was not significant. Furthermore, when comparing the results with the HP-CH4-GA experiment, it was observed that an increase in Ra and Rq values positively influenced gas adsorption, while an increase in Rsk and Rku values had an unfavorable effect on gas adsorption. This suggests that surface roughness plays a crucial role in gas adsorption behavior. Overall, the findings highlight the significant influence of different methods on the evaluation of pore structure. The 3D algorithm and ×4000 magnification provide a more accurate description of the pore structure. Additionally, the variation in 3D surface roughness was found to be related to coal rank and had a notable effect on gas adsorption.