Assessing efficacy of standard impregnation techniques on die-cast aluminum alloys using X-ray micro-CT

Utilizing lightweight Al alloys in various industrial applications requires achieving precise pressure tightness and leak requirements.Vacuum pressure impregnation(VPI)with thermosetting polymers is commonly used to address leakage defects in die-cast Al alloys.In this study,the efficacy of the VPI technique in sealing alloy parts was investigated using a combination of nondestructive micro X-ray computed tomography(micro XCT)and a standard leak test.The results demonstrate that the commonly used water leak test is insufficient for determining the sealing performance.Instead,micro XCT shows distinct advantages by enabling more comprehensive analysis.It reveals the presence of a low atomic number impregnates sealant within casting defects,which has low grey contrast and allows for visualizing primary leakage paths in 3D.The effective atomic number of impregnated resin is 6.75 and that of Al alloy is 13.69 by dual-energy X-ray CT.This research findings will contribute to enhancing the standard VPI process parameters and the properties of impregnating sealants to improve quality assurance for impregnation in industrial metals.

Effects of dry-wet cycles on three-dimensional pore structure and permeability characteristics of granite residual soil using X-ray micro computed tomography

Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive tool for characterizing the microstructure of soil samples exposed to a range of damage levels induced by dry-wet cycles.Subsequently,the variations of pore distribution and permeability due to drywet cycling effects were revealed based on three-dimensional(3D)pore distribution analysis and seepage simulations.According to the results,granite residual soils could be separated into four different components,namely,pores,clay,quartz,and hematite,from micro-CT images.The reconstructed 3D pore models dynamically demonstrated the expanding and connecting patterns of pore structures during drywet cycles.The values of porosity and connectivity are positively correlated with the number of dry-wet cycles,which were expressed by exponential and linear functions,respectively.The pore volume probability distribution curves of granite residual soil coincide with the χ^(2)distribution curve,which verifies the effectiveness of the assumption of χ^(2)distribution probability.The pore volume distribution curves suggest that the pores in soils were divided into four types based on their volumes,i.e.micropores,mesopores,macropores,and cracks.From a quantitative and visual perspective,considerable small pores are gradually transformed into cracks with a large volume and a high connectivity.Under the action of dry-wet cycles,the number of seepage flow streamlines which contribute to water permeation in seepage simulation increases distinctly,as well as the permeability and hydraulic conductivity.The calculated hydraulic conductivity is comparable with measured ones with an acceptable error margin in general,verifying the accuracy of seepage simulations based on micro-CT results.

矿物表面解离度分析技术发展综述

矿物解离程度显著影响浮选分离效率,矿物在颗粒表面解离行为的精准解析是实现浮选过程高效调控的前提。总结了矿物加工领域常见的矿物表面解离度分析方法:基于扫描电子显微镜(SEM)的2D解离度分析、2D解离度的体视学修正和3D解离度分析方法(X射线显微断层扫描成像技术)。2D解离度分析方法应用于低解离度粗粒连生体时存在体视学偏差,并且复杂共伴生颗粒的2D矿物解离度体视学修正仍面临挑战。2D解离分析适用于矿物单体解离或者高度解离的传统浮选处理的细颗粒,而对于矿物解离度较低的粗颗粒,3D解离度分析不存在体视学偏差,可提供更准确的表面解离度分析结果。

Multi-modality measurement and comprehensive analysis of hepatocellular carcinoma using synchrotron-based microscopy and spectroscopy

The visualization and data mining of tumor multidimensional information may play a major role in the analysis of the growth,metastasis,and microenvironmental changes of tumors while challenging traditional imaging and data processing techniques.In this study,a general trans-scale and multi-modality measurement method was developed for the quantitative diagnosis of hepatocellular carcinoma(HCC)using a combination of propagation-based phase-contrast computed tomography(PPCT),scanning transmission soft X-ray microscopy(STXM),and Fourier transform infrared micro-spectroscopy(FTIR).Our experimental results reveal the trans-scale micro-morpho-logical HCC pathology and facilitate quantitative data analysis and comprehensive assessment.These results include some visualization features of PPCT-based tissue microenvironments,STXM-based cellular fine structures,and FTIR-based bio-macromolecular spectral characteris-tics during HCC tumor differentiation and proliferation.The proposed method provides multidimensional feature data support for constructing a high-accuracy machine learning algorithm based on a gray-level histogram,gray-gradient co-occurrence matrix,gray-level co-occurrence matrix,and back-propagation neural network model.Multi-dimensional information analysis and diagnosis revealed the morphological pathways of HCC pathological evolution and we explored the relationships between HCC-related feature changes in inflammatory microenviron-ments,cellular metabolism,and the stretching vibration peaks of biomolecules of lipids,proteins,and nucleic acids.Therefore,the proposed methodology has strong potential for the visualization of complex tumors and assessing the risks of tumor differentiation and metastasis.

Micro porosity and its effect on fatigue performance of 7050 aluminum thick plates

Micro porosity in aluminum alloys may contribute to fatigue life degradation, which can largely limit the application of alloys. Therefore, the fatigue life of a commercial 7050-T7451 thick plate and an experimental plate with different porosities was compared in this study. The X-ray computed tomography(XCT) was utilized to characterize the size, number density and spatial distribution of porosity inside various samples, and the fracture surface of fatigued specimens was compared by using scanning electron microscope(SEM). The results showed that the fatigue cracks prefer to initiate from constituent particles in the commercial alloy. Whereas the micro porosity is the predominant site for crack nucleation and subsequent failure in the experimental one. The presence of micro porosity in experimental7050-T7451 thick plate may reduce the fatigue life by an order of magnitude or more compared with the defect-free alloy. The pores close to sample surface are the main fatigue crack initiation site, among which larger and deeper pore leads to a shorter fatigue life. The crack initiation is also affected by the pore geometry and direction. Besides, the overall porosity inside the bulk can affect the crack propagation during fatigue tests.

Adaptive enhancement design of triply periodic minimal surface lattice structure based on non-uniform stress distribution

The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this paper,an adaptive enhancement design method based on the non-uniform stress distribution in structures with uniform thickness is proposed to design the P-type TPMS lattice structures with higher mechanical properties.Two types of structures are designed by adjusting the adaptive thickness distribution in the TPMS.One keeps the same relative density,and the other keeps the same of non-enhanced region thickness.Compared with the uniform lattice structure,the elastic modulus for the structure with the same relative density increases by more than 17%,and the yield strength increases by more than 10.2%.Three kinds of TPMS lattice structures are fabricated by laser powder bed fusion(L-PBF)with 316L stainless steel to verify the proposed enhanced design.The manufacture-induced geometric deviation between the as-design and as-printed models is measured by micro X-ray computed tomography(μ-CT)scans.The quasi-static compression experimental results of P-type TPMS lattice structures show that the reinforced structures have stronger elastic moduli,ultimate strengths,and energy absorption capabilities than the homogeneous P-TPMS lattice structure.

锥形束显微CT技术在颞骨成像中的应用及发展

颞骨及其内部中、内耳结构细小复杂,各种颞骨疾病如先天性中耳畸形或中耳炎症等都可能导致不同程度的听力损失,认识颞骨内结构的精细解剖是疾病诊疗的第一步。显微计算机断层成像技术是一种新兴影像技术,分辨率达微米量级,可得到颞骨活体或标本的中、内耳结构,较目前临床CT观察到更加精细的中、内耳结构以及复杂的毗邻关系,尤其为认识中耳生理、病理传声机制提供帮助。

Fracture evolution in coalbed methane reservoirs subjected to liquid nitrogen thermal shocking

Thermal shocking effect occurs when the coalbed methane(CBM)reservoirs meet liquid nitrogen(LN2)of extremely low temperature.In this study,3D via X-ray microcomputer tomography(μCT)and scanning electron microscope(SEM)are employed to visualize and quantify morphological evolution characteristics of fractures in coal after LN2 thermal shocking treatments.LN2 thermal shocking leads to a denser fracture network than its original state with coal porosity growth rate increasing up to 183.3%.The surface porosity of theμCT scanned layers inside the coal specimen is influenced by LN2 thermal shocking which rises from 18.76%to 215.11%,illustrating the deformation heterogeneity of coal after LN2 thermal shocking.The cracking effect of LN2 thermal shocking on the surface of low porosity is generally more effective than that of high surface porosity,indicating the applicability of LN2 thermal shocking on low-permeability CBM reservoir stimulation.The characteristics of SEM scanned coal matrix in the coal powder and the coal block after the LN2 thermal shocking presented a large amount of deep and shallow progressive scratch layers,fracture variation diversity(i.e.extension,propagation,connectivity,irregularity)on the surface of the coal block and these were the main reasons leading to the decrease of the uniaxial compressive strength of the coal specimen.

Static dissolution-induced 3D pore network modification and its impact on critical pore attributes of carbonate rocks

To determine the effect of dissolution on pore network development in carbonate rocks, dissolution experiments, X-Ray microtomography, and thin section analysis were conducted on argillaceous limestone and grain limestone samples at different temperatures and constant pH, HCl concentration. The relationship between Ca^(2+) concentration and time was revealed through the experiments; pore size distribution before and after dissolution indicate that there is no correlation between the temperature and pore size variation, but pore size variation in grain limestone is more significant, indicating that the variation is mainly controlled by the heterogeneity of the rock itself(initial porosity and permeability) and the abundance of unstable minerals(related to crystal shape, size and mineral type). At different temperatures, the two kinds of carbonate rocks had very small variation in pore throat radius from 0.003 mm to 0.040 mm, which is 1.3 to 3.5 times more, 1.7 on average of the original pore throat radius. Their pore throat length varied from 0.05 mm to 0.35 mm. The minor changes in the pore throat radius, length and connectivity brought big changes to permeability of up to 1 000×10^(-3) μm^2.

Multiscale morphological analysis of bone microarchitecture around Mg-10Gd implants

The utilization of biodegradable magnesium(Mg)-based implants for restoration of bone function following trauma represents a transformative approach in orthopaedic application.One such alloy,magnesium-10 weight percent gadolinium(Mg-10Gd),has been specifically developed to address the rapid degradation of Mg while enhancing its mechanical properties to promote bone healing.Previous studies have demonstrated that Mg-10Gd exhibits favorable osseointegration;however,it exhibits distinct ultrastructural adaptation in comparison to conventional implants like titanium(Ti).A crucial aspect that remains unexplored is the impact of Mg-10Gd degradation on the bone microarchitecture.To address this,we employed hierarchical three-dimensional imaging using synchrotron radiation in conjunction with image-based finite element modelling.By using the methods outlined,the vascular porosity,lacunar porosity and the lacunar-canaliculi network(LCN)morphology of bone around Mg-10Gd in comparison to Ti in a rat model from 4 weeks to 20 weeks post-implantation was investigated.Our investigation revealed that within our observation period,the degradation of Mg-10Gd implants was associated with significantly lower(p<0.05)lacunar density in the surrounding bone,compared to Ti.Remarkably,the LCN morphology and the fluid flow analysis did not significantly differ for both implant types.In summary,a more pronounced lower lacunae distribution rather than their morphological changes was detected in the surrounding bone upon the degradation of Mg-10Gd implants.This implies potential disparities in bone remodelling rates when compared to Ti implants.Our findings shed light on the intricate relationship between Mg-10Gd degradation and bone microarchitecture,contributing to a deeper understanding of the implications for successful osseointegration.

Bridging the structure gap between pellets in artificial dissolution media and in gastro-intestinal tract in rats

Changes in structure of oral solid dosage forms(OSDF) elementally determine the drug release and its therapeutic effects.In this research,synchrotron radiation X-ray micro-computed tomography was utilized to visualize the 3 D structure of enteric coated pellets recovered from the gastrointestinal tract of rats.The structures of pellets in solid state and in vitro compendium media were measured.Pellets in vivo underwent morphological and structural changes which differed significantly from those in vitro compendium media.Thus,optimizations of the dissolution media were performed to mimic the appropriate in vivo conditions by introducing pepsin and glass microspheres in media.The sphericity,pellet volume,pore volume and porosity of the in vivo esomeprazole magnesium pellets in stomach for2 h were recorded 0.47,1.55 × 10^(8)μm^(3),0.44 × 10^(8)μm^(3)and 27.6%,respectively.After adding pepsin and glass microspheres,the above parameters in vitro reached to 0.44,1.64 × 10^(8)μm^(3)0.38 × 10^(8)μm^(3)and 23.0%,respectively.Omeprazole magnesium pellets behaved similarly.The structural features of pellets between in vitro media and in vivo condition were bridged successfully in terms of 3 D structures to ensure better design,characterization and quality control of advanced OSDF.

Effect of Bio-filler on Hybrid Sisal-Banana-Kenaf-Flax Based Epoxy Composites:A Statistical Correlation on Flexural Strength

This work deals with the investigation of the synergistic effect of bagasse ash with sisal-banana-kenaf-flax fibers reinforced epoxy composite for their flexural behavior.The composites with three combinations of hybrid fibers viz.sisal/kenaf(HSK),banana/kenaf(HBK),and banana/flax(HBF)with bagasse ash(BGA)as filler material are fabricated using vacuum bag assisted resin transfer molding.Experiments were conducted based on L27 orthogonal array to understand the influence of control factor viz.fiber volume,alkali concentration&BGA over output response.A'-ray micro computed tomography analysis was conducted over the developed sample to infer the uniform dispersion of fiber and filler material.The experimental results reveal that the addition of fiber up to 30 vol%depicts better strength and further addition results in a negative impact.Increasing in order of BGA decreases the flexural strength of the developed composites.