Utilization of Municipal Solid Waste Incineration Bottom Ash as Fine Aggregate of Cement Mortars

Incineration bottom ash is generated by the incineration of solid waste. Household solid waste is increasing every year and so is incineration bottom ash. This is a problem to treat the incineration bottom ash because the ash has many toxic components. Cement composites can solve this problem and there are many studies for using the bottom ash as fine aggregate. To evaluate the usage of incineration bottom ash, compressive strength, mercury intrusion porosimetry, scanning electron microscopy-backscatter electron, X-ray diffraction, and toxicity characteristic leaching processes were performed. When using incineration bottom ash up to 20% of substitution, the compressive strength in all cases was increased. This study showed how the filler effect appeared well in the cement composites through the scanning electron microscopy-backscatter electron, and mercury intrusion porosimetry. X-ray diffraction indicated the possibility of an alkali-silica reaction of the aggregate with the components of incineration bottom ash. This problem is an obstacle to applying the incineration bottom ash as a fine aggregate. In addition, the toxicity characteristic leaching process was shown to be under the threshold of the Korean standard, however, this should nuanced by the consideration of amorphity. Comprehensively, incineration bottom ash could be used as a fine aggregate of up to 20% of substitution. However, the pre-treatment would need to eliminate or reduce alkali reactive components and heavy metals.

Texture constraints on crystal size distribution methodology: An application to the Laki fissure eruption

Modeling crystal size distributions often requires the extraction of 2D discrete crystal lengths to calculate 3D volumetric equivalences. These apparent lengths are obtained from digital images that exploit different physical and chemical characteristics of samples, and the choice of image type can affect the interpretation of crystal length measurements, thus affecting crystal size distribution modeling. To examine method- and texture-based effects on extracting crystal size distributions, we obtained plagioclase length measurements from two texturally opposing basaltic lava samples from the well-documented Laki fissure eruptions of 1783–1784. Using approaches that consider inherent texture-based limitations of 2D image types, we employed manual tracing and imaging software to extract plagioclase crystal lengths from three types of images: (1) photomicrographs from polarized-light microscopy, (2) backscatter electron images from scanning electron microscopy, and (3) energy-dispersive X-ray maps from automated mineralogy. Our results demonstrate that (1) phenocrysts (L ≥ 150 μm) and groundmass plagioclase (L < 150 μm) in our basalt samples appear with multiple aspect ratios, while the latter also display greater nucleation densities as crystal size population are continuously refined over increasingly smaller crystal lengths; (2) complex crystal clusters must be manually dissected into their discrete crystal components to produce meaningful crystal size distributions; (3) localized electron backscatter diffraction analysis reveals mild preferred orientation in complex clusters and groundmass, the latter confirmed by variations in crystal size distributions between orthogonal backscatter electron images; and (4) method-induced variations in both aspect ratio and crystal length determination can produce a wide range of kinetic interpretations that pose challenges for cross-research comparisons. For phenocrysts, compensating for clustering and fracturing through manual tracing remains the most effective method, while groundmass populations can be addressed with high-resolution (micrometer-scale) automated scanning electron microscopy for deciphering late-stage eruptive behavior. A texture-focused protocol should be established, as any kinetic information derived from crystal size distribution analyses across multiple studies employing multiple approaches cannot otherwise be directly compared.

Micropredators skulking in Silurian oceans?

<p>Predation is potentially one of the most impactful evolutionary traits to have ever developed. Conodonts, an extinct group of early vertebrates, developed the first phosphatic dental tools, known as elements. Elements ranged from simple coniform types to more complex morphologies, predominantly in more derived species. Unlike the teeth of other vertebrates, these continuously grew throughout their lifetime by the periodic accretion of new lamellar tissues. This unique growth process continuously records chemical and physical characteristics throughout its lifespan which, when accessed, gives direct insight into the animal’s ecology and mode of life. Multiple lines of evidence, such as microwear studies and growth allometry, indicate that adult conodonts fed as predators and/or scavengers. There is little direct independent evidence for feeding ecologies in the earliest conodonts with coniform elements apparatuses, although previous modelling of element position and mechanical properties indicate these were capable of processing or manipulation of food. A direct test would be provided through evidence of tissue damage and its chemical composition. Our research focuses on samples of the coniform genus Panderodus (Family: Panderodontidae) from the Silurian of Poland and Ukraine. Panderodus has the best constrained apparatus reconstruction of any coniform conodont. Here we employ Backscatter electron (BSE) imaging and Energy-dispersive X-Ray spectroscopy (EDX) to identify growth dynamics, microwear, and chemical sclerochronology recorded within this unique mode of growth. Our results have direct implications not just for understanding the feeding mode of Panderodus, but also the origination of predation in the earliest vertebrates in the fossil record.</p>

Layerwise monitoring of electron beam melting via backscatter electron detection

Purpose The purpose of this study is the introduction and validation of a new technique for process monitoring during electron beam melting (EBM). Design/methodology/approach In this study, a backscatter electron detector inside the building chamber is used for image acquisition during EBM process. By systematic variation of process parameters, the ability of displaying different topographies, especially pores, is investigated. The results are evaluated in terms of porosity and compared with optical microscopy and X-ray computed tomography. Findings The method is capable of detecting major flaws (e.g. pores) and gives information about the quality of the resulting component. Originality/value Image acquisition by evaluating backscatter electrons during EBM process is a new approach in process monitoring which avoids disadvantages restricting previously investigated techniques.