Electron Microscopy Backscatter Research Articles

Interfacial bond behavior of steel fibers embedded in manufactured sand-based ultra-high performance concrete

The interfacial bond region between matrix and fibers is a non-negligible weak link that can significantly affect the mechanical properties of manufactured sand-based ultra-high-performance concrete (UHPMC). This study investigates the interfacial bond characteristics between steel fiber-UHPMC matrix using single-fiber pullout tests. Four variable parameters were considered: manufactured sand (MS) replacement ratio, stone powder content, fiber embedment length, and steel fiber geometry. Additionally, the microstructure of the steel fiber-UHPMC matrix interface was evaluated using backscattered electron microscopy (BSEM) and scanning electron microscopy (SEM). The results indicate that two typical failure modes including fiber pullout slip failure (in straight and hooked-end fibers) and fiber rupture failure (in corrugated fibers) were observed. The analysis of interfacial evaluation indicators shows that increasing the MS replacement ratio from 25 % to 100 % results in a decreasing trend in peak load, peak tensile stress, and energy consumption. Peak bond strength decreases with increasing embedment length. With the increase in stone powder content, the peak load, peak bond stress, and energy consumption increase initially and then decrease. Additionally, the interfacial failure mechanisms between straight/hooked-end steel fibers and the UHPMC matrix were further elucidated through bond-slip behavior characterization and microstructure analysis. Finally, a design-oriented bond-slip model was developed to predict the interfacial pull-out behavior of steel fiber -UHPMC matrix, showing favorable agreement between predicted and test results. These findings contribute to understanding the interfacial pullout behavior of steel fibers-UHPMC matrix, providing data reference for the performance optimization of UHPMC.

Sclerotic prostate cancer bone metastasis: woven bone lesions with a twist.

Bone metastases are the most severe and prevalent consequences of prostate cancer (PC), affecting more than 80% of patients with advanced PC. PCBMs generate pain, pathological fractures, and paralysis. As modern therapies increase survival, more patients are suffering from these catastrophic consequences. Radiographically, PCBMs are predominantly osteosclerotic, but the mechanisms of abnormal bone formation and how this pathological increase in bone density is related to fractures are unclear. In this study, we conducted a comprehensive analysis on a cohort of 76 cadaveric PCBM specimens and 12 cancer-free specimens as controls. We used micro-computed tomography to determine 3D organization and quantify bone characteristics, quantitative backscattering electron microscopy to characterize mineral content and details in bone structure, nanoindentation to determine mechanical properties, and histological and immunohistochemical analysis of bone structure and composition. We define 4 PCBM phenotypes: osteolytic, mixed lytic-sclerotic, and 2 subgroups of osteosclerotic lesions-those with residual trabeculae, and others without residual trabeculae. The osteosclerotic lesions are characterized by the presence of abnormal bone accumulated on trabeculae surfaces and within intertrabecular spaces. This abnormal bone is characterized by higher lacunae density, abnormal lacunae morphology, and irregular lacunae orientation. However, mineral content, hardness, and elastic modulus at micron-scale were indistinguishable between this irregular bone and residual trabeculae. The collagen matrix of this abnormal bone presents with irregular organization and a prominent collagen III composition. These characteristics suggest that osteosclerotic PCBMs initiate new bone deposition as woven bone; however, the lack of subsequent bone remodeling, absence of lamellar bone deposition on its surface, and presence of collagen III distinguish this pathologic matrix from conventional woven bone. Although the mineralized matrix retains normal bone hardness and stiffness properties, the lack of fibril anisotropy presents a compromised trabecular structure, which may have clinical implications.

Fabrication and characterization of Ti-12Mo/xAl2O3 bio-inert composite for dental prosthetic applications.

Introduction: Titanium (Ti)-molybdenum(Mo) composites reinforced with ceramic nanoparticles have recently significant interest among researchers as a new type of bio-inert material used for dental prosthetic applications due to its biocompatibility, outstanding physical, mechanical and corrosion properties. The current work investigates the impact of alumina (Al2O3) nanoparticles on the properties of the Ti-12Mo composite, including microstructure, density, hardness, wear resistance, and electrochemical behavior. Methods: Ti-12Mo/xAl2O3 nanocomposites reinforced with different Al2O3 nanoparticles content were prepared. The composition of each sample was adjusted through the mechanical milling of the elemental constituents of the sample for 24h under an argon atmosphere. The produced nanocomposite powders were then cold-pressed at 600 MPa and sintered at different temperatures (1,350°C, 1,450°C, and 1,500°C) for 90min. Based on density measurements using the Archimedes method, the most suitable sintering temperature was found to be 1,450°C. The morphology and chemical composition of the milled and sintered composites were analyzed using back-scattering scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results and Discussion: The results showed that the addition of Mo increased the Ti density from 99.11% to 99.46%, while the incorporation of 15wt% Al2O3 in the Ti-12Mo composite decreased the density to 97.28%. Furthermore, the Vickers hardness and wear behavior of the Ti-Mo composite were enhanced with the addition of up to 5 wt% Al2O3. The sample contains 5 wt% Al2O3 exhibited a Vickers hardness of 593.4HV, compared to 320HV for pure Ti, and demonstrated the lowest wear rate of 0.0367mg/min, compared to 0.307mg/min for pure Ti. Electrochemical investigations revealed that the sintered Ti-12Mo/xAl2O3 nanocomposites displayed higher corrosion resistance against a simulated artificial saliva (AS) solution than pure Ti. The concentrations of Ti, Mo, and Al ions released from the Ti-12Mo/xAl2O3 nanocomposites in the AS solution were within the safe levels. It was found from this study that; the sample of the composition Ti-12Mo/5wt%Al2O3 exhibited appropriate mechanical properties, biocompatibility, corrosion resistance against the AS solution with acceptable ion concentration released in the biological fluids. Therefore, it can be considered as a new bio-inert material for potential applications in dental prosthetics.

Dispersion Strategy improves the mechanical properties of 3D-Printed biopolymer nanocomposite

Homogenous dispersion of nanoparticles in polymer matrices is a technical challenge that if overcome can lead to improved mechanical properties of the resulting nanocomposites. In this work, we successfully refined commercially-available nanoscale, calcium deficient, and poorly crystalline hydroxyapatite (nHA) particles and composited them with acrylate and methacrylate functionalized soybean oil (mAESO) and triethylene glycol dimethacrylate (TEGDMA) producing inks for masked stereolithography (mSLA) -based 3D printing. First, we used shear mixing and ultrasonication on nHA/ethanol mixtures to break down agglomerates and then separated the finest nanoparticles from the remaining agglomerates using centrifugation. The refined nanoparticles (termed fine) were then mixed with the resins and UV-initiator to produce inks for 3D printing. Similarly, we prepared one ink using as-purchased nHA particles (termed raw) and another ink using leftover agglomerates after refinement (termed coarse). We compared the rheological properties of the nHA-resin inks. We used mSLA to fabricate nanocomposite specimens and tested them using flexural, and Mode-I fracture toughness testing following ASTM standards. The dispersion of nanoparticles in the polymer matrix was studied by analyzing backscattered mode scanning electron microscopy images. The nHA particle refinement improved the nanoparticle dispersion in the resin matrix while also increasing the viscosity and shear yield strength of the nanocomposite ink. The flexural fracture strength, flexural modulus, and Mode-I fracture toughness of refined nHA-based nanocomposites were increased by 11 %, 71 %, and 12 %, respectively compared to the raw nHA-based nanocomposites. However, the flexural fracture strain of refined nHA-based nanocomposites was lower by 40 % compared to the raw nHA-based nanocomposites. The nanocomposites became stiffer with the incorporation of refined nanoscale nHA. The separation of nanoscale nHA particles, excellent dispersion of these nanoparticles in polymer matrix, and improved flexural strength and modulus opens a new avenue towards the 3D printing of high-performance nHA-based nanocomposites.

Leaching-induced deterioration of shear bonding strength and micro-Vickers hardness of the ITZ modified by micro-SiO2 and nano-SiO2

The interfacial transition zone (ITZ) serves as a critical juncture between aggregate and cement paste in concrete, particularly vulnerable to calcium leaching. This study investigates the impact of water-cement (w/c) ratio and micro-SiO2 and nano-SiO2 content on the deterioration of shear bonding strength and micro-Vickers hardness of the ITZ during leaching. Analysis of ITZ micro-structure and elemental composition is conducted using backscattering electron microscope and energy dispersive spectroscopy (BSEM/EDS), and a deterioration model for the shear bonding strength of the leached ITZ is established. Results indicate that during leaching, shear bonding strength and micro-Vickers hardness of the ITZ are approximately 28 % and 67 % of those of the cement paste, respectively. A linear relationship between the shear bonding strength of the ITZ and its micro-Vickers hardness is observed when employing the same type of admixture. Mechanical properties and leaching resistance of the ITZ diminish progressively with increasing w/c ratio. Conversely, they exhibit an initial enhancement followed by decline with increasing micro-SiO2 and nano-SiO2 contents, with optimal contents of 8 % and 2 %, respectively. Micro-SiO2 and nano-SiO2 are found to enhance long- and short-term leaching resistance of cement-based materials, respectively. Additionally, the shear bonding strength of the ITZ decreases linearly with increased degree of area leaching. These findings enhance our understanding of the deterioration behavior of the ITZ and provide an important foundation for studying the durability changes of concrete subjected to calcium leaching.

Dynamic mechanical damping analysis of up/step-quenched Cu-Zn-Sn-based shape memory alloys

The effect of thermal quenching procedures on the damping properties of Cu-Zn-Sn-based SMAs is reported. Three compositions of Cu-Zn-Sn-based SMAs designated A (Cu-15.6Zn-12.1Sn), B (Cu-26.1Zn-9.3Sn), and C (Cu-29.6Zn-8.9Sn) samples produced by the casting process were subjected to direct quenching, up-quenching, and step-quenching treatments. The microstructure of the samples was examined using the backscattered electron microscope with fixtures for energy-dispersive spectroscopy analysis. The damping properties were assessed on a dynamic mechanical analyzer and presented in terms of tan delta. The microstructures of Cu-Zn-Sn-based SMAs consist of γ-Cu5Zn8 and Cu4 major phases containing some black dot precipitation and a small amount of white circular precipitates in the parent phase. For the A alloys, the step-quenched samples exhibited the highest damping capacity with peak internal friction of 0.041 at 37 °C, which is greater than 0.028 at 37 °C and 0.26 at 25 °C obtained for the up-quenched and direct-quenched samples respectively. The step-quenched B alloys show the highest damping capacity with peak internal friction of 0.104 at 227 °C, which is far greater than 0.053 at 23 °C and 0.034 at 35 °C obtained for the up-quenched and direct-quenched samples respectively. For the C alloys, the up-quenched samples show the highest damping capacity with peak internal friction of 0.053 at 235 °C, which is greater than the peak values of 0.037 at 23 8 °C obtained for the step-quenched samples. Direct-quenched samples gave the lowest damping capacity with a peak value of 0.027 at 235 °C. In general, step-quenching treatment effectively improved the damping properties of Cu-Zn-Sn-based SMAs.

Clarifying the contribution of multiscale pores to physical properties of Chang 7 tight sandstones: insight from full-scale pore structure and fractal characteristics

The pore structure and its heterogeneity of tight reservoirs are key factors affecting the storage and percolation of crude oil. The pore system of Chang 7 tight sandstone has multi-scale and multi-type characteristics. However, the contribution of different pore types and pore sizes to the physical properties of Chang 7 tight sandstone is still unclear. In this paper, we collected a suite of Chang 7 tight sandstones to investigate the full-scale pore structure and fractal characteristics by casting thin section, field emission scanning electron microscope, two-dimensional multi-scale backscattered scanning electron microscopy, N2 adsorption (NA) and NMR. The pore diameters of Chang 7 tight sandstone are usually distributed between 0.001 and 20 μm. Intercrystalline pores are mainly distuibuted <500 nm. Dissolution pores vary from 100 nm to 100 μm. Residual intergranular pores range from 1 μm to 40 μm. Based on the fractal characteristics, pore system is divided into macropores (mainly >300 nm), mesopores (mainly 7–300 nm), and micropores (mainly <7 nm). Micropores are adsorb-fluid pores that do not contribute to the storage and percolation but contribute significantly to contrasting specific surface area. Mesopores represent bound-fluid pores and only contribute to total porosity but not to permeability. Macropores represent movable-fluid pores, contributing to both porosity and permeability. The content and heterogeneity of macropores control the quality of Chang 7 tight sandstone. When macropore volume is >12×10−3 mL/g, the continuous percolation network consists entirely of macropores, resulting in higher porosity and permeability of the reservoir. Moreover, reservoir physical properties show excellent correlation with macropore heterogeneity. These results demonstrate that the content and heterogeneity of macropores are key indicators indicating the quality of the Chang 7 tight sandstones.

In-Column Backscattered Electron Microscopy for a Rapid Identification of the Number of Layers in MoS2 Nanosheets: Implications for Electronic and Optoelectronic Devices

In-Column Backscattered Electron Microscopy for a Rapid Identification of the Number of Layers in MoS₂ Nanosheets: Implications for Electronic and Optoelectronic Devices

Poly-ε-Caprolactone 3D-Printed Porous Scaffold in a Femoral Condyle Defect Model Induces Early Osteo-Regeneration.

Large bone reconstruction following trauma poses significant challenges for reconstructive surgeons, leading to a healthcare burden for health systems, long-term pain for patients, and complex disorders such as infections that are difficult to resolve. The use of bone substitutes is suboptimal for substantial bone loss, as they induce localized atrophy and are generally weak, and unable to support load. A combination of strong polycaprolactone (PCL)-based scaffolds, with an average channel size of 330 µm, enriched with 20% w/w of hydroxyapatite (HA), β-tricalcium phosphate (TCP), or Bioglass 45S5 (Bioglass), has been developed and tested for bone regeneration in a critical-size ovine femoral condyle defect model. After 6 weeks, tissue ingrowth was analyzed using X-ray computed tomography (XCT), Backscattered Electron Microscopy (BSE), and histomorphometry. At this point, all materials promoted new bone formation. Histological analysis showed no statistical difference among the different biomaterials (p > 0.05), but PCL-Bioglass scaffolds enhanced bone formation in the center of the scaffold more than the other types of materials. These materials show potential to promote bone regeneration in critical-sized defects on load-bearing sites.

Reducing the prosthesis modulus by inclusion of an open space lattice improves osteogenic response in a sheep model of extraarticular defect.

Introduction: Stress shielding is a common complication following endoprosthetic reconstruction surgery. The resulting periprosthetic osteopenia often manifests as catastrophic fractures and can significantly limit future treatment options. It has been long known that bone plates with lower elastic moduli are key to reducing the risk of stress shielding in orthopedics. Inclusion of open space lattices in metal endoprostheses is believed to reduce the prosthesis modulus potentially improving stress shielding. However, no in vivo data is currently available to support this assumption in long bone reconstruction. This manuscript aims to address this hypothesis using a sheep model of extraarticular bone defect. Methods: Initially, CT was used to create a virtual resection plan of the distal femoral metaphyses and to custom design endoprostheses specific to each femur. The endoprostheses comprised additively manufactured Ti6Al4V-ELI modules that either had a solid core with a modulus of ∼120GPa (solid implant group) or an open space lattice core with unit cells that had a modulus of 3-6GPa (lattice implant group). Osteotomies were performed using computer-assisted navigation followed by implantations. The periprosthetic, interfacial and interstitial regions of interest were evaluated by a combination of micro-CT, back-scattered scanning electron microscopy (BSEM), as well as epifluorescence and brightfield microscopy. Results: In the periprosthetic region, mean pixel intensity (a proxy for tissue mineral density in BSEM) in the caudal cortex was found to be higher in the lattice implant group. This was complemented by BSEM derived porosity being lower in the lattice implant group in both caudal and cranial cortices. In the interfacial and interstitial regions, most pronounced differences were observed in the axial interfacial perimeter where the solid implant group had greater bone coverage. In contrast, the lattice group had a greater coverage in the cranial interfacial region. Conclusion: Our findings suggest that reducing the prosthesis modulus by inclusion of an open-space lattice in its design has a positive effect on bone material and morphological parameters particularly within the periprosthetic regions. Improved mechanics appears to also have a measurable effect on the interfacial osteogenic response and osteointegration.

Development of high-strength lightweight concrete by utilizing food waste digestate based biochar aggregate

The application of carbon-negative biochar in cement composites can effectively reduce carbon emissions of construction materials. In this study, low-carbon composites were tailored with high volume of food waste digestate (FWD) biochar aggregate. The biochar was customized at different temperatures with the goal of enhancing the properties of cement-based composites. Backscattered electron microscopy (BSEM) images show that FWD biochar with a grey circle shape exhibited strong bonding with the cement matrix. Nano-indentation results indicate that the two statuses of FWD biochar showed visco-elastic and elastic-plastic modes of deformation, respectively. The FWD biochar aggregate prepared at higher pyrolysis temperatures (i.e., 650 °C and 750 °C) has higher elastic modulus (up to 11.4 GPa), which can be applied to make biochar blocks with higher strength and lower density compared to the biochar pyrolyzed at 550 °C. As a result, FWD 750BC blocks could reach 28-d compressive strength of 57.8 MPa and density of 1.77 g cm−3, which fulfilled the requirements of high-strength lightweight aggregate concrete. Hence, this study established a foundation to utilize FWD biochar as an aggregate in high-strength biochar construction materials.

Exploring the interfacial structure and crystallinity for direct growth of Mn3Sn(0001) on sapphire (0001) by molecular beam epitaxy

The Kagome antiferromagnet Mn3Sn has garnered a lot of attention due to the presence of interesting properties such as anomalous Hall effects and Nernst effects. Until now, few papers have been reported to grow using molecular beam epitaxy with a buffer layer or on other substrates. In this paper, we discuss the synthesis of crystalline Mn3Sn layers, prepared on Al2O3 (0001) without a buffer layer using molecular beam epitaxy. The growth is monitored in-situ using reflection high energy electron diffraction and measured ex-situ using X-ray diffraction, Rutherford back-scattering, and cross-sectional scanning transmission electron microscopy. The samples were deposited at 524 ± 5 °C, with an Mn: Sn atomic flux ratio of 3.2:1 for 90 min. Orientation relationships between the Mn3Sn films and the sapphire substrates are determined from in-plane and out-of-plane measurements. Our analysis indicates that the resulting film is predominantly c−plane oriented. Lastly, the samples prepared in this way were found to be discontiguous, showing a 3-dimensional morphology. According to first-principles calculations, the Mn3Sn exhibits a displaced Kagome structure in the very first stages of growth, for 2 ML and 4 ML growth on Al2O3 (0001). This result is corroborated by calculating the surface formation energies and explains the observed RHEED patterns.

Multiscale study of microstructural evolution in alkali-activated fly ash-slag paste at elevated temperatures

To promote the high-temperature application of alkali-activated fly ash-slag (AAFS), it is vital to thoroughly understand the performance of AAFS at elevated temperatures. This paper presents a systematic study on the multiscale microstructural evolution in AAFS paste in terms of nanostructure, chemical composition and morphology changes characterised using 29Si nuclear magnetic resonance, X-ray diffraction and Fourier transform infrared spectroscopy, as well as the pore structure evolution by means of mercury intrusion porosimetry, backscattered electron microscopy and X-ray microcomputed tomography. Results indicate that the decomposition of C-A-S-H and N–C-A-S-H gels occurs while gel pores are filled at elevated temperatures up to 800 °C, along with the crack development, whereas micro-cracks are healed by melting and viscous sintering. This study provides an in-depth insight into the damage mechanisms of AAFS paste at elevated temperatures from a multiscale viewpoint, accounting for Level I: solid gel particles, Level II: gel matrix, and Level III: AAFS paste.

Fatigue crack growth behavior of SS316L deposition from wire arc additive manufacturing

Wire arc additive manufacturing has shown the potential to build large metal parts with high deposition rates and low cost of production compared to other additive manufacturing techniques. Austenitic stainless steel 316L is known for corrosion resistance and weldability, which makes it a strong candidate for building and repairing marine and offshore parts, with wire arc additive manufacturing. These parts experience fluctuating loads during service, which necessitates the fatigue performance study of wire arc additively build stainless steel. This work investigates the fatigue crack propagation behavior of stainless steel 316L depositions from wire arc additive manufacturing. Single beads of stainless steel 316L were deposited layer by layer to fabricate the wall structures. From the wall structures, the specimens were prepared for the tensile and fatigue crack growth rate tests along the traverse and build directions. In conjunction with mechanical testing, electron back-scattered diffraction and scanning electron microscopy techniques were employed to characterize the microstructure. Microstructural observations showed the presence of columnar dendrites along the build direction. The electron dispersive spectroscopy revealed the elemental diffusion at the layer interfaces due to the remelting of the layers. Differences in mechanical properties were observed across the two directions. Along build directions, the ultimate tensile strength was 8 % higher and yield strength was 7 % lower than the respective strengths along the traverse direction. The build direction also exhibited 46 % higher fatigue life cycle than the traverse direction. The difference in properties across different orientations was closely associated with the microstructural variations. Overall, the mechanical performance of the wire arc additively deposited SS316L is better than the previously reported selective laser melted SS316L.

Autogenous self-healing induced by compressive fatigue in self-compacting steel-fiber reinforced concrete

We study the application of fatigue loads as an activation agent of the self-healing mechanism of concrete. This can lead to improvements in the strength of the material, contrary to the idea that cyclic loads can only generate damage. A fiber-reinforced concrete was produced and characterized under compressive fatigue. The strength of runout specimens, which resisted from a minimum of 165000 cycles until more than a million, showed a mean increase of 23%. Microstructure analyses were performed to confirm this increment as the result of a self-healing process, including X-ray Diffraction, Thermogravimetric and Differential Thermal Analyses, Back Scattering Electron Microscopy, and Mercury Intrusion Porosimetry. Results show the presence of new hydration products and a reduction of porosity, which explain the improvement of the concrete capacity. As a mechanical result, the relationship between strain rate and fatigue life is found to be unique for every fatigue stress level.

Molecular beam epitaxy and crystal structure of majority a-plane-oriented and substrate-strained Mn3Sn thin films grown directly on sapphire (0001)

The Kagome antiferromagnet Mn3Sn has garnered much attention due to the presence of exciting properties such as anomalous Hall and Nernst effects. This paper discusses the synthesis of crystalline Mn3Sn thin films, prepared on Al2O3 (0001) substrates at 453±5°C using molecular beam epitaxy. The growth is monitored in situ using reflection high energy electron diffraction and measured ex situ using x-ray diffraction, Rutherford back-scattering, and cross-sectional scanning transmission electron microscopy. Our analysis shows the in-plane lattice constants of a1,M=4.117±0.027 Å and a2,M=4.943±0.033 Å, which is a very unexpected result when compared to the bulk a-plane Mn3Sn. This indicates a strain in the film and makes it challenging to provide a straightforward explanation. In an effort to explain our results, we discuss two possible orientation relationships between the Mn3Sn films and the sapphire substrates. Samples prepared under these conditions appear to have smooth surfaces locally, but overall the film has a 3D island morphology. First-principles calculations provide atomic models of the Mn3Sn (112¯0) lattice on Al2O3 (0001) high symmetry sites, indicating that the L3-R90° is the most stable configuration. A detailed discussion of the experimental data and theoretical results, as well as strain effects, is provided.

From waste to wealth: Unlocking the value of copper anode slimes through systematic characterization and pretreatment

Technology, in addition to supply and demand, is driving current advances in mineral processing. Over the past three decades, demand for various minerals has continued to rise, while the mineral processing sector has faced challenges such as the need for more sophisticated ore treatment, lower plant feed quality, and poorer plant performance due to mixing of ores with varying characteristics. Gravity separation has long been a cost-effective method for the mining industry, especially in the processing of precious metals. Copper anode slime contains significant amounts of gold, silver, and platinum group metals. In this study, we tested the functionality of a slime shaking table for recovering precious metal components by recycling barite particles from the copper anode slime. Additionally, we used several characterization methods, including backscattered electron microscopy, energy-dispersive X-ray spectroscopy, optical microscopy, and physical testing, to improve our understanding of the copper anode slime particle phases. This study highlights the challenges associated with recycling and processing secondary materials and demonstrates the complexity of physical separation methods for extracting barite particles from copper anode slime.

Hydrothermal TiO2 polymorphs in a pyrite stratiform deposit: Lessons from a mineralogical and geochemical multiproxy record

This paper presents results of mineralogical and geochemical study of TiO2 polymorphs that occur within two hydrothermal stratiform zones of the Wiśniówka area (south-central Poland). These two mineralized zones consist primarily of alternating pyritiferous and REE-bearing sedimentary quartzites, quartzitic sandstones and silty-clayey shales. Of the TiO2 phases, anatase is a predominant type (mean of 56%) with a lesser amount of rutile (30%) and mixed rutile-anatase phases (11%) as well as rare rutile-brookite (2%) and brookite (1%) as evidenced by laser Raman microspectrometry. TiO2 polymorphs typically form interstitial euhedral to anhedral or skeleton-like grains and aggregations averaging 30–50 μm in diameter occasionally attaining 110 μm. Extremely scarce pyritiferous microfossils are infilled with needle- and lath-like anatase. Under backscattered electron microscope images, TiO2 grains are generally homogenous, in places with tiny inclusions of zircon, monazite, niobium oxide and palladium telluride. In addition, some rutile grains show oscillatory zonation or zonal-brecciated and patchy patterns. Results derived from electron microprobe examinations show enrichments of most TiO2 phases in niobium (up to 4.98 wt%), zirconium (up to 0.58 wt%) and tantalum (up to 0.57 wt%) substituting titanium in the TiO2 crystal structure. The TiNb pair shows the highest correlation (r2 = 0.98). Concentrations of these and other elements vary substantially within individual anatase/rutile grains. The lack of other potential Ti-bearing rock-forming or oxide minerals (e.g., biotite, pyroxene, hornblende, titanite, ilmenite, titanomagnetite, titanohematite) in sedimentary siliciclastic rocks of the study area also indicates that anatase and rutile may have crystallized along with prevailing pyrite, xenotime, aluminum-phosphate-sulfate (APS) minerals and most monazite directly from hydrothermal fluids at relatively low temperatures, presumably around 200 °C (range of 150 to 300 °C). Among these ore minerals, only goyazite and mixed goyazite-gorceixite aggregations contain up to 20.07 wt% Ti and 24.09 wt% Ti, respectively. Mineral and microtextural relationships show that TiO2 polymorphs may have formed in two phases under reducing and subsequently oxidizing conditions of the Wiśniówka Late Cambrian depositional basin.

Long-term effects of canagliflozin treatment on the skeleton of aged UM-HET3 mice.

Sodium glucose cotransporter-2 inhibitors (SGLT2is) promote urinary glucose excretion and decrease plasma glucose levels independent of insulin. Canagliflozin (CANA) is an SGLT2i, which is widely prescribed, to reduce cardiovascular complications, and as a second-line therapy after metformin in the treatment of type 2 diabetes mellitus. Despite the robust metabolic benefits, reductions in bone mineral density (BMD) and cortical fractures were reported for CANA-treated subjects. In collaboration with the National Institute on Aging (NIA)-sponsored Interventions Testing Program (ITP), we tested skeletal integrity of UM-HET3 mice fed control (137 mice) or CANA-containing diet (180ppm, 156 mice) from 7 to 22months of age. Micro-computed tomography (micro-CT) revealed that CANA treatment caused significant thinning of the femur mid-diaphyseal cortex in both male and female mice, did not affect trabecular bone architecture in the distal femur or the lumbar vertebra-5 in male mice, but was associated with thinning of the trabeculae at the distal femur in CANA-treated female mice. In male mice, CANA treatment is associated with significant reductions in cortical bone volumetric BMD by micro-CT, and by quantitative backscattered scanning electron microscopy. Raman microspectroscopy, taken at the femur mid-diaphyseal posterior cortex, showed significant reductions in the mineral/matrix ratio and an increased carbonate/phosphate ratio in CANA-treated male mice. These data were supported by thermogravimetric assay (TGA) showing significantly decreased mineral and increased carbonate content in CANA-treated male mice. Finally, the sintered remains of TGA were subjected to X-ray diffraction and showed significantly higher fraction of whitlockite, a calcium orthophosphate mineral, which has higher resorbability than hydroxyapatite. Overall, long-term CANA treatment compromised bone morphology and mineral composition of bones, which likely contribute to increased fracture risk seen with this drug.

Innovative image analysis-based methods for the estimation of conventional concrete mixture proportions from hardened concrete

The importance of concrete mix design is not hidden from anyone. Therefore, extracting mixture proportions from hardened concrete can be considered as a brilliant tool for various purposes such as controlling the accuracy of construction and evaluating the reasons for the inappropriate performance of concrete. For this purpose, an innovative and comprehensive method was developed in which images of the macrostructure and microstructure of hardened concrete were utilized. At first, the volume ratios of aggregates, cement paste, and air voids were estimated using the results of analyzing microstructure images containing images of black and white treated concrete cross sections scanned with a resolution of 2400 dpi and Backscattered electron microscopy (BSE) images at 500 × magnification. Subsequently, with regard to the aggregates volume ratio and images of the macrostructure of concrete, scanned with a resolution of 600 dpi, volume ratios of coarser aggregates (retained on the 0.3 mm sieve) and finer aggregates (passing the 0.3 mm sieve) were calculated. For determining aggregate size distribution, the sieve simulation and optimizing rules (SSOR) method was developed. Water to cement ratio was estimated by having volume ratios of cement paste components extracted from processing BSE images. Also, cement content was estimated using a proposed equation by having volume ratios of cement paste and water to cement ratio. Thus, using the proposed methods in this study, volume ratios of aggregates, cement paste, and air voids and aggregate size distribution, water to cement ratio, cement content, and water content can be estimated for an unknown hardened concrete. The statistical comparison between the actual mixture proportions and the results obtained from performing the proposed methods on samples made with three different aggregate size distributions and a range of cement content (300–500 kg/m3), and water to cement ratio (0.32–0.6) highlights the brilliant performance of the introduced methods.