Microstructure Formation Research Articles

A Comprehensive Study on the Microstructure and Mechanical Behavior of Glycoluril–Formaldehyde Polymer-Modified Cement Paste

Concrete is popular in construction due to its strong performance and low maintenance. However, some structures become unsafe over time due to poor maintenance and design flaws. As demand for maintenance grows, restoring older structures is a cost-effective option. Advanced repair techniques aim to extend service life and improve concrete properties, with a focus on eco-friendly solutions. Recent trends have highlighted the potential of incorporating polymers into repair methods, but the use of glycoluril–formaldehyde, a polymeric material known for its hydrogen bonding capacity, remains unexplored in repairing existing structures. This research investigates the effects of glycoluril–formaldehyde in simple matrices like cement paste and mortar to understand its impact. By examining the chemical reactions between glycoluril–formaldehyde with cement paste, this study delves into the fresh, mechanical, and microstructural characteristics. To evaluate the influence of glycoluril–formaldehyde, cement paste specimens were subjected to various tests, including consistency, initial and final setting time, and miniature slump flow tests. Cement mortar specimens were then subjected to compression strength tests conducted at various ages. The results demonstrate that a 3% addition of glycoluril–formaldehyde in concrete offers optimum performance, ensuring improved mechanical strength and microstructure. The microstructural investigation using optical microscopy, an X-ray diffraction, and SEM analysis confirms the polymerization of glycoluril–formaldehyde and the formation of a denser microstructure. The thermogravimetric (TG) and differential thermogravimetric (DTG) analysis provides crucial insights into the thermal stability of the cementitious system, aiding its characterization for high-temperature applications.

Influence of scanning speed and hatch distance on defects, microstructure, and mechanical performance of Fe–Mn–Al–Ni–C low-density steel fabricated via directed energy deposition

This study examined the effects of the directed energy deposition (DED) process parameters on the microstructural evolution, defect formation, and mechanical properties of Fe–Mn–Al–Ni–C low-density steel. The samples were fabricated in an Ar atmosphere by adjusting the scanning speed (600, 1000, 1400 mm/min) and hatch spacing (1.32, 1.11, 1.00 mm), and the influence of these process parameters on the porosity, microstructural characteristics, and compressive yield strength was analysed systematically. The experimental results showed that increasing the scanning speed and reducing the hatch spacing (1400 mm/min, 1.00 mm) decreased the amount of unmelted powder on top of the melt pool, reduced surface roughness, and significantly lowered the overall porosity. Under these conditions, however, the increased heat input reduced the cooling rate of the melt pool, promoting the growth of the ferrite/B2 (BCC) phase. This weakened the secondary phase strengthening effect, reducing the compressive yield strength (1058.02 ± 17.33 MPa). In contrast, a lower scanning speed (600 mm/min) and a larger hatch spacing (1.32 mm) accelerated the cooling rate of the melt pool and suppressed the growth of the ferrite/B2 phase, resulting in a fine and uniformly distributed microstructure and enhanced compressive yield strength (1183.02 ± 23.56 MPa). This study revealed the complex relationship between the DED process parameters, microstructure, porosity, and yield strength, providing a theoretical foundation and practical guidance for further optimising the forming process and improving the overall performance of this alloy.

Intracoronary Structural-Molecular Imaging for Multitargeted Characterization of High-Risk Plaque: First-in-Human OCT-FLIm.

Fluorescence lifetime imaging (FLIm) is a molecular imaging technique used to visualize the biochemical composition of atherosclerosis. Novel dual-modal imaging using optical coherence tomography (OCT)-FLIm has the potential to provide both microstructural and biocompositional information on coronary plaques; however, it needs validation for clinical application. To investigate the clinical feasibility and safety of OCT-FLIm for characterizing plaque compositions in patients with coronary artery disease (CAD) undergoing revascularization therapy. A prospective, open-label, single-center diagnostic feasibility study involving 40 patients with significant CAD requiring coronary revascularization. This first-in-human clinical study of the novel intracoronary OCT-FLIm imaging was conducted between February and August 2022. The analyses were performed from August 2022 to July 2023. An OCT-FLIm system with 2.6-F catheters was constructed. All patients underwent OCT-FLIm for target/culprit and nontarget/nonculprit lesions during coronary revascularization. Intravascular ultrasound imaging was performed for comparison. The primary outcome was to assess the FLIm-derived molecular readouts of prespecified plaque compositions. The secondary outcome was the feasibility of OCT-FLIm in determining target/culprit plaque compositions across different subsets of atherosclerotic disease activity: (1) acute coronary syndrome (ACS) vs chronic stable angina (CSA) and (2) angiographic rapid disease progression vs nonprogressive controls. We prospectively enrolled 40 patients (mean [SD] age, 63.1 [8.1] years; 32 men [80.0%]), of whom 20 presented with ACS and 20 with CSA. OCT provided the structural features of plaques, and FLIm characterized the molecular signatures of atheroma compositions, including macrophages, healed plaques, superficial calcification, and fibrosis, in a reproducible manner. Fluorescence lifetime (FL) values of the plaque compositions correlated with findings from prior autopsy studies. Plaque inflammation was significantly greater in patients with ACS than those with CSA. The mean (SD) of inflammation-FL was 7.59 (0.96) nanoseconds for patients with ACS vs 6.46 (0.87) nanoseconds for patients with CSA (P < .001). The healed plaque phenotype was more prominently distributed in the segments of rapid disease progression than in nonprogressive controls. The mean (SD) healed plaque-FL was 5.31 (0.20) nanoseconds for the rapidly progressive lesions vs 4.81 (0.30) nanoseconds for the rapidly nonprogressive lesions (P < .001). All patients underwent OCT-FLIm safely without adverse clinical events. This diagnostic feasibility study found that an OCT-FLIm structural-molecular intracoronary imaging is clinically feasible and safe for the comprehensive characterization of human atheromas, supporting its potential role in the diagnosis and biological understanding of high-risk plaques.

The recurrence of geophysical manifestations at the Campi Flegrei caldera.

The Campi Flegrei caldera (CFc), Italy, exhibits distinct unrest patterns, including shallow seismicity following substantial strain accumulation, all within a densely populated area. Previous geophysical studies typically analyzed individual episodes, but by comparing two distinct unrest periods we identified recurring manifestations and VP/VS anomalies linked to a confined reservoir at 2- to 4-kilometer depth. Integrating rock physics experiments under hydrothermal conditions, 24 years of rainfall data, and subsurface hydrodynamics, we found increasing rainfall rates, which indicate reservoir recharge and pressurization. We show that hydrothermal water promotes caprock sealing through the formation of a fibrous microstructure. Our experiments further demonstrate that fluid accumulation rates directly influence deformation rates. Together, these processes drive gradual deformation, natural seismicity, and deepening earthquake foci. Recognizing these recurring patterns is crucial for understanding the caldera's unrest-driving mechanism, enabling us to offer actionable insights for hazard assessment and engineering solutions, such as intercepting water upstream to prevent drainage toward Pozzuoli.

Characterization of MXene-Based Materials by X-Ray Computed Tomography.

MXenes are a class of 2D materials that have gained significant attention for their potential applications in energy storage, electromagnetic interference shielding, biomedicine, and (opto)electronics. Despite their broad range of applications, a detailed understanding of the internal architecture of MXene-based materials remains limited due to the lack of effective 3D imaging techniques. This work demonstrates the application of X-ray micro-computed tomography (micro-CT) to investigate various MXene systems, including nanocomposites, coated textiles, and aerogels. Micro-CT enables high-resolution, 3D visualization of the internal microstructure, MXene distribution, infiltration patterns, and defect formations, which significantly influence the material's performance. Moreover, the typical technical challenges and limitations encountered during sample preparation, scanning, and post-processing of micro-CT data are discussed. The information obtained from optical and electron microscopy is also compared with micro-CT, highlighting the unique advantages of micro-CT in providing comprehensive 3D imaging and quantitative data. This study highlights micro-CT as a powerful and nondestructive imaging tool for characterizing MXene-based materials, providing insights into material optimization and guidelines for developing future advanced applications.

Imaging the microstructure of the arterial wall - ex vivo to in vivo potential.

Microstructural imaging enables researchers to visualise changes in the arterial wall, allowing for (i) a deeper understanding of the role of specific components in arterial mechanics, (ii) the observation of cellular responses, (iii) insights into pathological alterations in tissue microstructure, and/or (iv) advancements in tissue engineering aimed at replicating healthy native tissue. In this prospective review, we present various imaging modalities spanning from ex vivo to in vivo applications within arterial tissue. The pros, cons, and sensitivities of these modalities are highlighted. By consolidating the latest advancements in microstructural imaging of arterial tissue, the authors aim for this paper to serve as a guide for researchers designing experiments at various stages. Furthermore, the integration of non-invasive, non-destructive imaging techniques into studies provides an additional layer of microstructural information, enhancing scientific findings, improving our understanding of disease, and potentially enabling earlier or more effective diagnostic capabilities. STATEMENT OF SIGNIFICANCE: Microstructural imaging enables researchers to visualise changes in the arterial wall, allowing for (i) a deeper understanding of the role of specific components in arterial mechanics, (ii) the observation of cellular responses, (iii) insights into pathological alterations in tissue microstructure, and/or (iv) advancements in tissue engineering aimed at replicating healthy native tissue. By consolidating the latest advancements in microstructural imaging of arterial tissue, the authors aim for this paper to serve as a guide for researchers designing experiments at various stages. Furthermore, the integration of non-invasive, non-destructive imaging techniques into studies provides an additional layer of microstructural information, enhancing scientific findings, improving our understanding of disease, and potentially enabling earlier or more effective diagnostic capabilities.

Ti3C2Tx MXene-Zirconium Diboride Based Ultra-High Temperature Ceramics.

MXenes are a family of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides with potential applications in ceramics and composites due to their nanometer-thick morphology, hydrophilic surfaces, and negative zeta potentials. In this study, we investigated titanium carbide MXene (Ti3C2Tx) as an additive in ultra-high-temperature ceramics (UHTCs), specifically zirconium diboride (ZrB2). Homogeneous green bodies of Ti3C2Tx and ZrB2 were synthesized via electrostatic self-assembly in aqueous media without surfactants and subsequently densified using field-assisted (spark plasma) sintering. The incorporation of 0.5wt.% MXene enhanced the relative density of ZrB2 from ≈89% (pure ZrB2) to ≈96% under identical sintering conditions. MXene addition significantly reduced the oxygen content from ≈5 at.% in pure ZrB₂ to ≈2-3 at.% at 2.5wt.% MXene loading. The presence of MXene also facilitates the formation of a core-shell microstructure, where (Zr,Ti)B2 shells encapsulate ZrB₂ cores, with arrays of dislocations observed at the core-shell interface. Mechanical characterizations show substantial improvements, including a 36% increase in hardness, a ≈12% enhancement in Young's modulus, and a ≈15% increase in flexural strength at 2.5wt.% MXene loading. These findings demonstrate the potential of MXenes as effective sintering aids and reinforcement agents in UHTCs, offering promising pathways for advancing materials designed for extreme environments.

Exploring Anthracene in Laser-Induced Carbon Plasma Studies with Long-Wave Infrared Laser-Induced Breakdown Spectroscopy for Understanding Carbon Microstructure Formation in Space

Exploring Anthracene in Laser-Induced Carbon Plasma Studies with Long-Wave Infrared Laser-Induced Breakdown Spectroscopy for Understanding Carbon Microstructure Formation in Space

Relationship Between Structure and Functional Properties of Ultrafine-Grained Fe-Mn-Si Alloys for Temporary Implants

This paper presents a study of microstructure formation in bioresorbable Fe-Mn-Si alloys for temporary implants under high-pressure torsion (HPT) at room temperature and at 300 °C. The effect of silicon on the mechanism of microstructure formation under HPT and, as a consequence, on the mechanical, corrosion and biological properties of the alloys is studied. It is established that Si promotes martensitic transformation. HPT leads to an increase in the microhardness values of the studied alloys from ~1560 MPa in the initial state to ~5500 MPa (160–560 HV) due to structure refinement and phase transformation. An increase in the electrochemical corrosion rate of Fe-Mn-Si alloys to ~0.5 mm/year is established due to grain refinement to nanosize and the formation of strain-induced martensite. In vitro cytotoxicity and induced hemolysis studies showed that Fe-Mn, Fe-Mn-3.7Si, and Fe-Mn-5Si alloys after annealing and HPT can be characterized as biocompatible.

Static Recrystallization Simulation of Interstitial Free‐Steel by Coupling Multi‐Phase‐Field and Crystal Plasticity Model Considering Dislocation Density Distribution

Knowledge of alloy recrystallization is key to optimizing microstructures and achieving superior material properties. Computational models predicting microstructural evolution during recrystallization significantly enhance control of microstructure formation during manufacturing. Accurate prediction of microstructural parameters, including recrystallization fraction and grain size, is highly desirable. However, developing robust recrystallization models under various processing conditions remains an active research area. Herein, using interstitial free‐steel for simulations and experiments, plastic deformation of polycrystalline material is simulated using a physics‐based crystal plasticity model. A real microstructure serves as the initial configuration. The resulting inhomogeneous dislocation density distribution and deformed grain topology are used in a multi‐phase‐field simulation of recrystallization. In primary recrystallization, nucleation strongly influences kinetics and the final microstructure. In the model, the dislocation density distribution predicts both the number and positions of nuclei. Comparing simulations—one considering the dislocation density distribution in both nucleation and evolution and the other assuming constant dislocation density and random seed positioning—demonstrates the importance of heterogeneous dislocation distribution. Results confirm that static recrystallization simulations, accurately reflecting plastic deformation and utilizing the dislocation density distribution as the driving force for grain growth and nucleation, can be successfully performed using the proposed model.

Application of neutron grating interferometry and tomography to the nineteenth century Korean copper coins

Distinguishing differences between authentic artifacts and replicas is a significant challenge in the field of cultural heritage. In this study, we explore the application of neutron grating interferometry and tomography techniques to identify Korean copper coins in the nineteenth century of Joseon period by investigating structural differences between genuine objects and replicas. Neutron grating interferometry provides the microstructural information of coins, including features such as pores and precipitates, through a dark field image derived from small-angle neutron scattering. Additionally, neutron transmission tomography examines the three-dimensional internal structures and potentially hidden features of coins. Both neutron imaging techniques highlight regions that contain lead precipitates in the copper alloy, showing consistent agreement with optical imaging and with the quantitative lead content measured by energy dispersive X-ray spectroscopy. The distinct corrosion patterns observed in the authentic coin and replica provide empirical explanations for the general corrosion mechanism of copper alloy. This interpretation finds support in the moderate contribution of dark field contrast from cuprite, which underlies the signal of lead precipitates.

Unraveling the major role of vascular (R2') contributions to R2* signal relaxation at ultra-high-field MRI: A comprehensive analysis with quantitative gradient recalled echo in mouse brain.

Ultra-high-field (UHF) R2* relaxometry is often used for in vivo analysis of biological tissue microstructure without accounting for vascular contributions to R2* signal, that is, the BOLD signal component, and magnetic field inhomogeneities. These effects are especially important at UHF as their contribution to R2* scales linearly with magnetic field. Our study aims to report on the results of separate contributions of R2t* (tissue-specific sub-component) and R2' (vascular BOLD sub-component), corrected for the adverse effects of magnetic field inhomogeneities, to the total R2* signal at in vivo UHF MRI of mouse brain. Four healthy, 8-week-old C57BL/6J mice were imaged in vivo with multi-gradient echo MRI at 9.4 T and analyzed using the quantitative gradient recalled echo (qGRE) approach. A segmentation protocol was established using the Dorr Mouse Brain Atlas and ANTs Syn registration to warp template brain region labels to subject qGRE maps. By separating R2' contribution from R2* signal, we have established normative R2t* data in mouse brain. Our findings revealed significant contributions of R2' to R2*, with approximately 42% of the R2* signal arising from vascular contributions, thus suggesting the R2t* as a more accurate metric for quantifying tissue microstructural information and its changes in neurodegenerative diseases. qGRE approach allows efficient separation of tissue microstructure-specific (R2t*), vascular BOLD (R2'), and background gradients contributions to the total R2* relaxation at UHF MRI. Due to low concentration of non-heme iron in mouse brain, major contribution to R2t* results from tissue cellular components.

INFLUENCE OF CHEMICAL COMPOSITION WITH HEAT TREATMENT OF STEEL ON THE STRUCTURE AND MECHANICAL PROPERTIES OF A KNIFE BLADE

Introduction. The main requirement for high-quality knife steel is its balanced chemical composition and appropriate heat treatment, which provides optimal indicators of hardness, wear resistance and corrosion resistance of the cutting part. It is the combination of these characteristics that determines the operational properties of the knife, including its ability to hold the cutting edge for a long time and resist mechanical and chemical influences. Modern industry offers a wide range of high-quality materials for the manufacture of knives, including tool steels, special die steels, as well as high-tech steels obtained by powder metallurgy. The use of powder technologies allows you to achieve a homogeneous microstructure, increased wear resistance and improved strength, which makes such materials especially popular among manufacturers of high-quality knives. Materials and methods. In this work, structural ball bearing steel ShKh15Sh (TU 141594, DSTU 4738:007) and heat-resistant stainless steel 40X13 (DSTU 4738:007) were used, which are combined with each other by the method of furnace welding. Steel ShKh15Sh is a high-carbon alloy steel with high hardness and excellent wear resistance, which makes it suitable for the manufacture of the cutting part. At the same time, steel 40X13 is characterized by high corrosion resistance and impact toughness, which allows it to be used for composite material linings. Thus, the resulting composite blade combines the rigidity and sharpness of the cutting part with the mechanical strength and corrosion resistance of the outer layers. The results of the experiment. In the course of research, it was found that changes in the chemical composition of the 40КХНМ alloy significantly affect its mechanical properties, including hardness and resistance to shock loads. An increase in the content of carbon, molybdenum and chromium in the alloy leads to an increase in its hardness. This is with the formation of stronger carbide and molybdenum phases in the structure of the alloy, which leads to an improvement in its mechanical properties. Increased hardness makes the alloy more resistant to wear and increases its durability in operating conditions. An increase in the nickel content in the alloy leads to an increase in its resistance to shock loads. This is caused by an increase in plasticity and impact toughness of the alloy with an increased nickel content. Higher resistance to shock loads makes the alloy suitable for use in conditions that require high resistance to shocks, for example, in the production of machine parts and equipment. A mathematical model of the dependence of the strength of the alloy on the percentage content of the components of the chemical composition was built, which allows to control the indicators of the strength of the alloy in the process of its manufacture. Conclusions. To compare the effectiveness of different materials, a blade made of N690 steel (Böhler, Austria) is also studied − a high-quality cobalt stainless steel of the martensitic class. Adding cobalt to the alloy contributes to the formation of a finer-grained microstructure, which improves the overall performance characteristics of the material. In addition, this steel is known for its high hardness (up to 60 HRC after heat treatment) and wear resistance, which makes it popular among manufacturers of premium knives. Conclusions. Further analysis of the comparative characteristics of the obtained blades will allow to determine their optimal areas of application and assess the effectiveness of the use of composite materials in the knife industry.

Assessing the Microstructure of SnBiZn Alloys during Semisolid Treatment

The development of new alloys for semisolid processing is a key demand of Industry 4.0, driven by the limited knowledge in this area, particularly for Sn‐based alloys. The primary goal is to design alloys suitable for thixocasting and semisolid additive manufacturing. While Zn is known to influence SnBi alloys by affecting their microstructure, wettability, and intermetallic compound formation, its impact on globule size, morphology, and microstructural coarsening/stability over aging remains largely unexplored, despite the potential implications for semisolid processability and final product reliability. In this research, stability in high‐temperature experiments is verified for the Sn40Bi and Sn40Bi2Zn alloys (wt%). Five different heat treatment periods of 20, 40, 60, 90, and 120 min are applied to the samples, each subjected to its respective eutectic temperature according to CALPHAD computations. The microstructure of both alloys is characterized by Sn‐rich globules for times higher than 90 min, which are noticeably finer and less elongated in the Sn40Bi2Zn alloy compared to the Sn40Bi. This globule refinement in Sn40Bi2Zn alloy can be attributed to the presence of Zn needles at the dendrite boundaries that pin the Sn‐rich regions and prevent them from growing freely. Over time, while Bi saturates near its solubility limit in Sn matrix at 60 min and remains stable up to 120 min, the Sn40Bi2Zn alloy exhibits a progressive increase in Bi content between 60 and 120 min, reaching the saturation level at 120 min. The Sn40Bi2Zn alloy exhibits higher globule microhardness in the 90 min samples, primarily due to Zn hardening in solid solution.

Si3N4 Nanoparticle Reinforced Si3N4 Nanofiber Aerogel for Thermal Insulation and Electromagnetic Wave Transmission

Traditional nanoparticle aerogels suffer from inherent brittleness and thermal instability at elevated temperatures. In recent years, ceramic nanofiber aerogels, utilizing flexible nanofibers as structural units, have emerged as mechanically resilient alternatives with ultrahigh porosity (&gt;90%). However, their thermal insulation capabilities are compromised by micron-scale pores (10–100 μm) and overdependence on ultralow density, which exacerbates mechanical fragility. This study pioneers a gas-phase self-assembly strategy to fabricate Si3N4 nanoparticle reinforced Si3N4 nanofiber aerogels (SNP-R-SNFA) with gradient pore architectures. By leveraging methyltrimethoxysilane/vinyltriethoxysilane composite aerogel (MVa) as a reactive template, we achieved spontaneous growth of Si3N4 nanofiber films (SNP-R-SNF) featuring nanoparticle-fiber interpenetration and porosity gradients. The microstructure formation mechanism of SNP-R-SNF was analyzed using field-emission scanning electron microscopy. Layer assembly and hot-pressing composite technology were employed to prepare the SNP-R-SNFA, which showed low density (0.033 g/cm3), exceptional compression resilience, insensitive frequency dependence of dielectric properties (ε′ = 2.31–2.39, tan δ &lt; 0.08 across 8–18 GHz). Infrared imaging displayed backside 893 °C cooler than front, demonstrating superior insulation performance. This study not only provides material solutions for integrated electromagnetic wave-transparent/thermal insulation applications but more importantly establishes an innovative paradigm for enhancing the mechanical robustness of nanofiber-based aerogels.

Combined effect of ultrasonic pretreatment and drying temperature on the quality characteristics of honeysucks puree under microwave vacuum drying

To achieve high efficient dehydration and anthocyanin retention in honeysucks, a novel drying strategy is developed through ultrasonic pretreatment (USP) to accelerate the moisture diffusion followed by controllable temperature under microwave vacuum drying (MVD) to reduce the degradation of anthocyanins. The ultrasound power (240, 480, 720, 960, 1200 W), USP duration (0, 15, 30, 45, 60 min) and MVD temperature (40, 50, 60, 70 °C) were selected as factors influencing the drying efficiency and anthocyanin content in honeysucks puree. Compared with the untreated control group, the drying time of the ultrasonically pretreated samples decreased by 17.31% to 32.14%. After ultrasonic pretreatment, the proportion of free water in the puree increased significantly, while the proportion of bound water decreased significantly by about 61%. Scanning electron microscope observation showed that the ultrasonic pretreatment of honeysucks puree resulted in a loose and porous internal structure. The enhancement of USP on the moisture diffusion in honeysucks puree is determined via the formation of sponge microstructure, the weakness of the binding force of water molecules with solid matrix, the conversion of bound water into free water. The correlation between ultrasonic pretreatment and the drying temperature in microwave vacuum drying is analyzed to determine the compensatory effect of USP-enhanced diffusion capability for the reduction in the moisture transfer caused by the low temperature under microwave vacuum drying. High-intensity USP promotes the total anthocyanin content release from 21.57% to 35.71% and enhances the anthocyanin retention by 9.65% to 23.59% under microwave vacuum drying. The results provide an explanation for the application of ultrasonic pretreatment to enhance the quality of microwave vacuum drying honeysucks puree.

Mechanism Study on the Influence of Clay-Type Lithium Slag on the Properties of Cement-Based Materials.

With the increasing demand for lithium resources and the enhancement of global environmental awareness, how to efficiently and environmentally develop clay-type lithium resources is of great strategic significance for future development. Clay-type lithium slag (LS) is a byproduct resulting from the extraction of lithium from clay-type lithium ores. Its primary chemical constituents include SiO2 and Al2O3, and it exhibits potential pozzolanic properties. Clay-type lithium ore is of low grade, so a large amount of clay-type LS is produced during its production. In this study, calcined clay-type LS, limestone powder (LP), and cement clinker were used as the main raw materials to prepare low-carbon LC3 cementitious materials. The study focused on the effect of clay-type LS and LP on the new mixing properties, mechanical properties, hydration kinetics, and microstructure formation and transformation of the cementitious materials. The findings revealed that incorporating clay-type LS and LP significantly raised the standard consistency water demand of cement and reduced the setting time of the binding material. While clay-type LS and LP initially weakened the mechanical performance of the cement mortar, it enhanced these properties in the later stages. The compressive strength of LC-10 and LC-20 at 180 days exceeded that of the reference by 3.7% and 1.1%, respectively. In addition, the number of micropores between 3 and 20 nm in LC3 cement increased significantly. It showed that the addition of clay-type LS and LP could optimize the pore structure to some extent. According to research, the optimal content of clay-type LS and LP should not exceed 30%. This method not only consumes the solid waste of clay-type LS, but also facilitates the green and low-carbon transformation of the cement industry.

The Effect of Sulfur Concentration on the Crystallization and Electrochemical Behavior of Portland Cement

Portland cement is a critical material widely used in the construction industry, where its crystallization and microstructure are key factors determining its physical and mechanical properties. This study investigated the effect of sulfur on the crystallization and microstructure of Portland cement. Sulfur acts as either an additive or an impurity during the cement production process, influencing the crystal size, distribution, and microstructure formation of major hydration products such as C3S (tricalcium silicate), C2S (dicalcium silicate), C3A (tricalcium aluminate), and C4AF (tetracalcium aluminoferrite). Through quantitative and qualitative evaluation using XRD, SEM, and EPMA analytical techniques, this study examined changes in the hydration characteristics, crystal structure, and microstructure of Portland cement with varying sulfur concentrations. The results revealed that increased sulfur content promotes the crystal growth of C3A and the formation of ettringite, which alters the density of the structure during the early stages of hydration and affects its long-term strength properties. These findings suggest that controlling the sulfur content plays a significant role in optimizing the performance and durability of Portland cement. This study highlights the potential for developing high-performance cement by regulating sulfur levels during the production process, contributing to advancements in construction materials.

Influence of Cr on the quaternary FeTaTiW medium entropy alloy

The search for advanced materials has been growing, and high entropy alloys (HEAs) are emerging as promising candidates for application in the fusion domain. This work investigates the effect of Cr on the FeTaTiW medium entropy alloy to form (CrFeTaTi)70W30 high entropy alloy, comparing the experimental production and characterization with the simulation (molecular dynamics and hybrid molecular dynamics-Monte Carlo) of the phases formed. The alloys were produced by mechanical alloying and sintered by spark plasma sintering. Both simulations have shown that a body-centered cubic structure is formed for both compositions. Monte Carlo simulation provides a more precise prediction of microstructural formation and element segregation. Microstructural examination of the consolidated material revealed the presence of a W-rich phase and a Ti–rich phase, consistent with the phase separation observed in the MC simulations. Moreover, X-ray diffraction analysis of the milled powder for FeTaTiW and (CrFeTaTi)70W30 confirmed the formation of a bcc (body-centered cubic)-type structure with a low fraction of intermetallic phases. Mechanical testing showed ductile behavior at 1000 °C where (CrFeTaTi)70W30 showed a stress magnitude almost double that of FeTaTiW. Additionally, the thermal diffusivity between 20 and 1000 °C of both alloys increases as the temperature rises. (CrFeTaTi)70W30 exhibits an increase from 3 to 5 mm2/s, while FeTaTiW increases from 4 to 9 mm2/s. Still, both system’s thermal diffusivity values are lower than those of CuCrZr and pure tungsten. Despite this, the study underscores the promising attributes of HEAs and highlights areas for further optimization to enhance its suitability for extreme conditions.

Brain age identification from diffusion MRI synergistically predicts neurodegenerative disease

Abstract Estimated brain age from magnetic resonance image (MRI) and its deviation from chronological age can provide early insights into potential neurodegenerative diseases, supporting early detection and implementation of prevention strategies to slow disease progression and onset. Diffusion MRI (dMRI), a widely used modality for brain age estimation, presents an opportunity to build an earlier biomarker for neurodegenerative disease prediction because it captures subtle microstructural changes that precede more perceptible macrostructural changes. However, the coexistence of macro- and micro-structural information in dMRI raises the question of whether current dMRI-based brain age estimation models are leveraging the intended microstructural information or if they inadvertently rely on the macrostructural information. To develop a microstructure-specific brain age, we propose a method for brain age identification from dMRI that mitigates the model’s use of macrostructural information by non-rigidly registering all images to a standard template. Imaging data from 13,398 participants across 12 datasets were used for the training and evaluation. We compare our brain age models, trained with and without macrostructural information mitigated, with an architecturally similar T1-weighted (T1w) MRI-based brain age model and two recent, popular, openly available T1w MRI-based brain age models that primarily use macrostructural information. We observe difference between our dMRI-based brain age and T1w MRI-based brain age across stages of neurodegeneration, with dMRI-based brain age being older than T1w MRI-based brain age in participants transitioning from cognitively normal (CN) to mild cognitive impairment (MCI) (p-value = 0.023), but younger in participants already diagnosed with Alzheimer’s disease (AD) (p-value &amp;lt; 0.001). Classifiers using T1w MRI-based brain ages generally outperform those using dMRI-based brain age in classifying CN vs. AD participants. Conversely, dMRI-based brain age may offer advantages over T1w MRI-based brain age in predicting the transition from CN to MCI.