33 research outputs found
EDS microanalysis of blast furnace slag grains in aged concrete
No full textThe chemistry of ground granulated blast furnace slag (GGBFS) is one of the main factors affecting its reactivity. Knowing the composition of GGBFS used in aged concrete may help understand its past performance and estimate remaining service life. It is well known that GGBFS generally react slower than cement clinker. This thesis proposes that partially hydrated GGBFS grains found in aged concrete could be used to determine its chemical composition. The feasibility of using standard-based energy dispersive X-ray spectroscopy (EDS) microanalysis, along with electron imaging, as a tool for quantitative measurement of the chemical composition of GGBFS grains in cement/concrete is explored in this research. X-ray spectra collected from minerals or glasses of known composition are known as standards for quantitative EDS microanalysis. This study initially examined the performance of mineral and slag standards to quantify X-ray spectra obtained from GGBFS-cement paste specimens of known composition. Parameters such as GGBFS properties, experimental conditions, and microanalysis methodologies that affect the EDS quantitative total and accuracy were elaborated. Then, the same standards were used to quantify the unknown composition of GGBFS used in seven concrete specimens collected in the Netherlands representing different service life, which revealed the variation in GGBFS chemistry over the years. Finally, as a supplementary study, the variation in significant hydration products formed due to variation in GGBFS composition in a cement-GGBFS system was predicted using thermodynamic modelling with GEMS. Altogether, it was concluded that standard-based EDS is a solid tool to characterize the chemical composition of GGBFS used in aged concrete.Civil Engineerin
A Review of Global Path Planning Algorithms for Planar Navigation of Autonomous Underwater Robots
No full textEDS Microanalysis of Unhydrated Blast Furnace Slag Grains in Field Concrete with Different Service Life
No full textBecause the essential quality metrics of blast furnace slag are based on its oxide composition, the determination of chemical compositions of unhydrated slag grains in an aged concrete could be useful for understanding its past performance and in predicting the remaining service life of existing slag-bearing concrete. In this research, the authors explored the feasibility of using standard-based energy-dispersive X-ray spectroscopy (EDS) microanalysis, in tandem with electron imaging, as a tool for quantitative measurement of the chemical composition of blast furnace slag grains in cement/concrete. In the experimental study, seven concrete samples representing various service life durations were collected in the Netherlands. The microanalysis results of the samples revealed that the change in slag chemistry is insignificant for samples B (1985) to F (2006); however, elevated CaO and SiO2 contents are found in slag used for sample G (2015), opposite to that of Al2O3 and MgO. After discussing compositional characterization, the paper discusses favorable microanalysis protocols for acceptable elemental quantification accuracy. It was concluded that quantitative EDS microanalysis is a strong tool to characterize the chemical composition of unhydrated slag used in field concrete, which could potentially contribute to understanding the correlations between composition and long-term performance in slag concrete structures. Materials and Environmen
WITHDRAWN: Analytical solution of an amperometric biosensor based on catalase-peroxidase biochemical reactions using Homotopy perturbation method
No full textThis article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy
Facile synthesis of SnO2/α-Fe2O3 nanocomposite for supercapacitor capacitor applications
No full textSome Critical Reflections on the SEM-EDS Microanalysis of the Hydrotalcite-like Phase in Slag Cement Paste
No full textFor a better understanding of the hydrotalcite-like phase with SEM-EDS microanalysis, the present research paid special attention to the data acquisition and interpretation of this technique. A lower Mg/Al ratio was obtained when using a higher accelerating voltage, and a beam energy of 10 kV was more appropriate than 15 kV for investigation when the slag rim was thin, to compromise to meet the requirements of obtaining an adequate overvoltage ratio and minimizing the interference. Additionally, it was noted that the Mg/Al ratio decreased from zones rich in hydrotalcite-like phase to zones rich in the C−S−H gel phase, and indiscriminately fitting scatter points selected from the slag rim would bias the Mg/Al ratio of the hydrotalcite-like phase. According to the standard-based microanalysis, it was concluded that the analysis total of the hydrates within the slag rim was in the range of 30–40%, lower than that located in the cement matrix. Besides the water chemically bound in the C−S−H gel phase, the hydrotalcite-like phase also contained a certain amount of hydroxide ions and chemically bound water
Primary neuroendocrine carcinoma of the breast: A rare entity
No full textNeuroendocrine carcinomas of the breast are a rare and distinct entity that is not routinely encountered in clinical practice. The diagnosis of primary neuroendocrine breast carcinoma is mainly a diagnosis of exclusion as the metastatic disease is more common a possibility. The algorithmic approach in the evaluation of such tumors includes the clinical and radiological examination of the breast lumps followed by correlation with Histopathological study and Immunohistochemistry tests. We report a case of primary neuroendocrine carcinoma of the breast in a 64-year-old female who presented with breast lump for one month duration
