This article deals with an analysis of mixing and determines the admixing rate of a base S355 steel plate in single-bead surface welds by measuring the chemical composition using a plane-scan energy ...dispersive X-ray spectroscopy (EDXS) on metallographic cross-sections. The results show that obtaining a larger number of EDXS measurements does not necessarily lead to obtaining a more accurate admixing rate. Due to the ever-present segregations that are generally near the base material, the disadvantage of this method is the subjective influence of the SEM operator on the estimated admixing rate. To obtain relevant results, a sufficiently wide area of well-mixed melt, including segregations, must be analyzed. This study showed that by using a sufficiently large number of appropriately selected sites with a sufficiently large surface area, it is possible to estimate the admixing rate from the chemical composition with an accuracy of ≥96% for the geometrically determined admixing rate
= 30%. From several equations, the best result showed an equation which is the arithmetic mean of the two different arithmetic means and in which the artificial influencing factor of the segregations of the base material is taken into account. With this equation, the same value of admixing rate,
= 30%, was obtained using the comparative geometric method.
A large (47.75 ± 3.56 µm in diameter) Thiovulum bacterial strain forming white veils is described from a marine mangrove ecosystem. High sulfide concentrations (up to 8 mM of H
2
S) were measured on ...sunken organic matter (wood/bone debris) under laboratory conditions. This sulfur-oxidizing bacterium colonized the organic matter, forming a white veil. According to conventional scanning electron microscope (SEM) observations, bacterial cells are ovoid and slightly motile by numerous small flagella present on the cell surface. Large intracytoplasmic internal sulfur granules were observed, suggesting a sulfidic-based metabolism. Observations were confirmed by elemental sulfur distribution detected by energy-dispersive X-ray spectroscopy (EDXS) analysis using an environmental scanning electron microscope (ESEM) on non-dehydrated samples. Phylogenetic analysis of the partial sequence of 16S rDNA obtained from purified fractions of this Epsilonproteobacteraeota strain indicates that this bacterium belongs to the Thiovulaceae cluster and could be one of the largest Thiovulum ever described. We propose to name this species Candidatus Thiovulum sp. strain imperiosus.
The evolution of a nanostructured state of palladium—lead membrane alloys during their interaction with hydrogen was studied using precision X-ray diffraction with synchrotron radiation (SR) and ...scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDXS). The importance of this topic is due to the need and demand for improving the performance characteristics of dense metal diffusion filters for high purity hydrogen separation processes. Palladium-based membrane filters with lead concentrations of 5 and 20 wt.% were prepared via electric arc melting from high purity metals (99.95%). The thickness of the filters was 50 μm. Hydrogenation was carried out from a gas medium at 573 K and the pressure of 16 atm. within 150 min. The focus of the study is on the structural state of diffusion filter membranes depending on the content of the palladium-alloying element—lead—and on analysis of the substructure of alloys before and 5300 h relaxation after hydrogenation is carried out. Specific features of the surface morphology and the structure of the membrane filters depending on the concentration of lead in the alloys are determined. The formation and development of deformation processes in metal systems upon the hydrogenation is shown. The establishment of peculiarities of hydrogen interaction with metals will contribute to obtaining new potentially important characteristics of membrane filters.
In this study we successfully applied the ζ-factor method to perform quantitative X-ray analysis of organic thin films consisting of light elements. With its ability to intrinsically correct for ...X-ray absorption, this method significantly improved the quality of the quantification as well as the accuracy of the results compared to conventional techniques in particular regarding the quantification of light elements. We describe in detail the process of determining sensitivity factors (ζ-factors) using a single standard specimen and the involved parameter optimization for the estimation of ζ-factors for elements not contained in the standard. The ζ-factor method was then applied to perform quantitative analysis of organic semiconducting materials frequently used in organic electronics. Finally, the results were verified and discussed concerning validity and accuracy.
•The ζ-factor method is used for quantitative EDXS analysis of light elements.•We describe the process of determining ζ-factors from a single standard in detail.•Organic semiconducting materials are successfully quantified.
The Caribbean bivalves Codakia orbicularis (Linné, 1758) and C. orbiculata (Montagu, 1808) live in seagrass beds of Thalassia testudinum and harbor intracellular sulfur-oxidizing ...gamma-proteobacteria. These bacterial symbionts fix CO2 via the Calvin Benson cycle and provide organic compounds to the bivalve. During experimentally induced starvation, no reduced sulfur compounds and no organic particle food are available; the symbionts could be considered as the sole nutrient source of the host bivalve. A previous study has shown that the intracellular bacterial population decreased considerably during starvation and that bacterial endosymbionts were not released by the bivalves. In this study, the activity of two lysosomal marker enzymes (acid phosphatase and arylsulfatase) was detected using cytochemical experiments coupled with energy-dispersive X-ray transmission electron microscopy during sulfide and organic particle starvation. The degradation of bacterial endosymbionts began after 2 weeks of starvation in C. orbiculata and after 3 weeks in C. orbicularis. Degradation processes seem to be continuous over several months and could be responsible for the disappearance of the bacterial endosymbionts within the gills during starvation. These data suggest that the host use symbionts as a nutrient source to survive a hunger crisis. The carbon transfer from the symbionts to the host could be flexible and could consist in transfer of organic matter, "milking," under normal feeding conditions and digestion of the symbionts under starved conditions.
Haplognathia ruberrima is a cosmopolitan gnathostomulid species found in sulfur bacterial mats in mangroves in Guadeloupe (French West Indies). Haplognathia ruberrima presents a δ13C value lower than ...all measured meiofaunal grazers and lower than the available measured food sources of this environment. This low δ13C value can not be due to specific ingestion of 13C‐depleted methanogenic bacteria because abundances of those bacteria are reduced in surficial and deep sediments as revealed by δ13C of bacterial fatty acid. According to scanning electron microscope observations, no bacterial ectosymbionts were observed at the surface of the gnathostomulids, and transmission electron microscope views revealed the absence of bacterial endosymbionts. Energy‐dispersive X‐ray spectroscopy analysis detected low levels of sulfur (0.32%±0.8) in biological tissues of H. ruberrima, confirming the absence of thioautotrophic bacterial symbionts in these animals. Consequently, the low δ13C value of H. ruberrima can not be due to the presence of sulfur‐oxidizing symbionts but more probably to the selective and exclusive consumption of free‐living, sulfur‐oxidizing bacteria.
Traffic-related non-exhaust particulate matter mainly consists of tire wear, brake wear, and road wear. For this study, passive-samplers were placed near highly frequented roads in industrial, ...agricultural, and urban environments with the aim of collecting and characterizing super-coarse (＞ 10 μm) airborne particles. Single-particle analysis using SEM-EDX was conducted on more than 500 particles with nearly 1500 spectra to determine their size, shape, volume, and chemical composition. The ambient aerosol near all studied roads is dominated by traffic-related abrasion particles, amounting to approximately 90 vol%. The majority of the particles were composites of tire-, road-, and brake-abrasion material. The particle assemblages differed in size distribution, composition, and structure depending on driving speed, traffic flow, and traffic fleet. Our study documents that tire wear significantly contributes to the flux of microplastics into the environment. A decrease in the release of this abrasion material, however, is unlikely in the near future.
This study explores the use of waste granite and tin oxide nanoparticles (SnO2 NPs) as replacements for sand in mortar composites containing Ordinary Portland Cement (OPC), Hydrated Lime (HL), and ...Quarry Sand (QS). Scanning electron microscopy (SEM) imaging revealed an increase in particle distribution between voids in the control mortar, enhancing photon absorption. The density of the prepared mortar samples exhibited a notable increment, with a 2.12–2.30 g/cm3 increase through the inclusion of SnO2-NPs. Additionally, the Phy-X software was employed to experimentally measure and theoretically calculate the linear attenuation coefficient (LAC), demonstrating a high degree of agreement between the two values. The LAC values were found to increase with the replacement ratio of granite waste and SnO2 nanoparticles, demonstrating the effectiveness of these materials as radiation shielding agents. This study investigates the effect of substituting waste granite and SnO2 nanoparticles for sand in mortars, resulting in an increase in LAC levels, indicating potential for improved radiation shielding capabilities, although the degree of change in LAC may be energy-dependent. The half value results (HVL) results demonstrated a significant decrease in required material thickness for radiation shielding applications with numerical values of 1.153, 0.734, 0.456, 0.351, and 0.261 cm for the control, Mor-1, Mor-2, Mor-3, and Mor-4 samples, respectively, at an energy of 0.06 MeV.
•Waste granite and SnO2 NPs enhance mortar composites for gamma-ray shielding.•Density of mortar samples increased notably with SnO2-NPs inclusion.•Experimental and theoretical LAC values show strong agreement.•Increased LAC with higher ratios of granite waste and SnO2 nanoparticles.•Significant decrease in required thickness for radiation shielding with composite mortars.
Precipitation holds a pivotal role in comprehending the intrinsic behavior of materials. In the design of nanostructured metallic alloys, precipitates have found to increase the alloys' stability and ...response under extreme environmental conditions. Studies on precipitation often rely on conventional and ex situ electron-microscopy methods, but a systematic investigation that compares different sample conditions during heat treatment and its microstructural implications are rarely available. In this context, we employed a novel ultrafine-grained AlMgZnCuAg crossover alloy to compare three distinct conditions for investigating the precipitation sequence: (i) ex situ transmission electron microscopy (TEM) from bulk heating, (ii) ex situ TEM from TEM foil heating, and (iii) in situ TEM with microelectromechanical-system (MEMS) heating. Although the heat treatment procedure was consistent across all cases studied, the application of these three different experimental conditions in the same alloy system resulted in significant and non-negligible differences in the final precipitation behavior. Ultimately, it resulted in observable microstructural variations and precipitates with distinctively different shape and sizes and, as a result, we outline herein the major similarities and differences among these techniques to achieve comparable results. This knowledge will help to compare and assess results of precipitation sequences obtained in different conditions.
•TEM ex situ and in situ heating experiments on an ultrafine-grained AlMgZnCuAg crossover alloy were employed.•They revealed a notable disparity in the kinetics of precipitates, resulting in a modification in the microstructure.•Thin film phenomena were observed: solute atoms, like Mg, tend to evaporate during in situ TEM with MEMS heating experiments.•In ex situ TEM with TEM foil heating, Mg is likely to form a protective oxide layer, inhibiting further evaporation.•Kinetics showed the following trend: ex situ TEM with TEM foil heating >ex situ bulk method >in situ TEM with MEMS heating.
Tires, bitumen, and road markings are important sources of traffic-derived carbonaceous wear particles and microplastic (MP) pollution. In this study, we further developed a machine-learning ...algorithm coupled to an automated scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analytical approach to classify and quantify the relative number of the following subclasses contained in environmental road dust: tire wear particles (TWP), bitumen wear particles (BiWP), road markings, reflecting glass beads, metallics, minerals, and biogenic/organics. The method is non-destructive, rapid, repeatable, and enables information about the size, shape, and elemental composition of particles 2–125 µm. The results showed that the method enabled differentiation between TWP and BiWP for particles > 20 µm with satisfying results. Furthermore, the relative number concentration of the subclasses was similar in both analyzed size fractions (2–20 µm and 20–125 µm), with minerals as the most dominant subclass (2–20 µm
x̄
= 78%, 20–125 µm
x̄
= 74%) followed by tire and bitumen wear particles, TBiWP, (2–20 µm
x̄
= 19%, 20–125 µm
x̄
= 22%). Road marking wear, glass beads, and metal wear contributed to
x̄
= 1%,
x̄
= 0.1%, and
x̄
= 1% in the 2–20-µm fraction and to
x̄
= 0.5%,
x̄
= 0.2%, and
x̄
= 0.4% in the 20–125-µm fraction. The present results show that road dust appreciably consists of TWP and BiWP within both the coarse and the fine size fraction. The study delivers quantitative evidence of the importance of tires, bitumen, road marking, and glass beads besides minerals and metals to wear particles and MP pollution in traffic environments based on environmental (real-world) samples
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