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Matt L. Weier - One of the best experts on this subject based on the ideXlab platform.
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thermal treatment of Whewellite a thermal analysis and raman spectroscopic study
Thermochimica Acta, 2004Co-Authors: Ray L. Frost, Matt L. WeierAbstract:Abstract Thermal transformations of natural calcium oxalate monohydrate known in mineralogy as Whewellite have been undertaken using a combination of thermal analysis and Raman microscopy with the use of a thermal stage. High resolution thermogravimetry shows that three mass loss steps occur at 162, 479 and 684 °C. Evolved gas mass spectrometry shows that water is evolved in the first step and carbon dioxide in the second and third mass loss steps. The changes in the molecular structure of Whewellite can be followed by the use of the in situ Raman spectroscopy of Whewellite at the elevated temperatures. The Whewellite is stable up to around 161 °C, above which temperature the anhydrous calcium oxalate is formed. At 479 °C, the oxalate transforms to calcium carbonate with loss of carbon dioxide. Above 684 °C, calcium oxide is formed.
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Thermal treatment of Whewellite—a thermal analysis and Raman spectroscopic study
Thermochimica Acta, 2004Co-Authors: Ray L. Frost, Matt L. WeierAbstract:Abstract Thermal transformations of natural calcium oxalate monohydrate known in mineralogy as Whewellite have been undertaken using a combination of thermal analysis and Raman microscopy with the use of a thermal stage. High resolution thermogravimetry shows that three mass loss steps occur at 162, 479 and 684 °C. Evolved gas mass spectrometry shows that water is evolved in the first step and carbon dioxide in the second and third mass loss steps. The changes in the molecular structure of Whewellite can be followed by the use of the in situ Raman spectroscopy of Whewellite at the elevated temperatures. The Whewellite is stable up to around 161 °C, above which temperature the anhydrous calcium oxalate is formed. At 479 °C, the oxalate transforms to calcium carbonate with loss of carbon dioxide. Above 684 °C, calcium oxide is formed.
Ray L. Frost - One of the best experts on this subject based on the ideXlab platform.
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thermal treatment of Whewellite a thermal analysis and raman spectroscopic study
Thermochimica Acta, 2004Co-Authors: Ray L. Frost, Matt L. WeierAbstract:Abstract Thermal transformations of natural calcium oxalate monohydrate known in mineralogy as Whewellite have been undertaken using a combination of thermal analysis and Raman microscopy with the use of a thermal stage. High resolution thermogravimetry shows that three mass loss steps occur at 162, 479 and 684 °C. Evolved gas mass spectrometry shows that water is evolved in the first step and carbon dioxide in the second and third mass loss steps. The changes in the molecular structure of Whewellite can be followed by the use of the in situ Raman spectroscopy of Whewellite at the elevated temperatures. The Whewellite is stable up to around 161 °C, above which temperature the anhydrous calcium oxalate is formed. At 479 °C, the oxalate transforms to calcium carbonate with loss of carbon dioxide. Above 684 °C, calcium oxide is formed.
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Thermal treatment of Whewellite—a thermal analysis and Raman spectroscopic study
Thermochimica Acta, 2004Co-Authors: Ray L. Frost, Matt L. WeierAbstract:Abstract Thermal transformations of natural calcium oxalate monohydrate known in mineralogy as Whewellite have been undertaken using a combination of thermal analysis and Raman microscopy with the use of a thermal stage. High resolution thermogravimetry shows that three mass loss steps occur at 162, 479 and 684 °C. Evolved gas mass spectrometry shows that water is evolved in the first step and carbon dioxide in the second and third mass loss steps. The changes in the molecular structure of Whewellite can be followed by the use of the in situ Raman spectroscopy of Whewellite at the elevated temperatures. The Whewellite is stable up to around 161 °C, above which temperature the anhydrous calcium oxalate is formed. At 479 °C, the oxalate transforms to calcium carbonate with loss of carbon dioxide. Above 684 °C, calcium oxide is formed.
Alok K. Mukherjee - One of the best experts on this subject based on the ideXlab platform.
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Phase composition and morphological characterization of human kidney stones using IR spectroscopy, scanning electron microscopy and X-ray Rietveld analysis.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2018Co-Authors: Paramita Chatterjee, Arup Chakraborty, Alok K. MukherjeeAbstract:Abstract Pathological calcification in human urinary tract (kidney stones) is a common problem affecting an increasing number of people around the world. Analysis of such minerals or compounds is of fundamental importance for understanding their etiology and for the development of prophylactic measures. In the present study, structural characterization, phase quantification and morphological behaviour of thirty three (33) human kidney stones from eastern India have been carried out using IR spectroscopy (FT-IR), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Quantitative phase composition of kidney stones has been analyzed following the Rietveld method. Based on the quantitative estimates of constituent phases, the calculi samples have been classified into oxalate (OX), uric acid (UA), phosphate (PH) and mixed (MX) groups. Rietveld analysis of PXRD patterns showed that twelve (36%) of the renal calculi were composed exclusively of Whewellite (calcium oxalate monohydrate, COM). The remaining twenty one (64%) stones were mixture of phases with oxalate as the major constituent in fourteen (67%) of these stones. The average crystallite size of Whewellite in oxalate stones, as determined from the PXRD analysis, varies between 93 (1) nm and 202 (3) nm, whereas the corresponding sizes for the uric acid and struvite crystallites in UA and PH stones are 79 (1)–155 (4) nm and 69 (1)–123(1) nm, respectively. The size of hydroxyapatite crystallites, 10 (1)–21 (1) nm, is smaller by about one order of magnitude compared to other minerals in the kidney stones. A statistical analysis using fifty (50) kidney stones (33 calculi from the present study and 17 calculi reported earlier from our laboratory) revealed that the oxalate group (Whewellite, weddellite or mixture of Whewellite and weddellite as the major constituent) is the most prevalent (82%) kidney stone type in eastern India.
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Compositional and architectural variation in urinary calculi from nucleus to periphery: an integrated IR spectroscopy, scanning electron microscopy and powder X‐ray diffraction approach
Journal of Applied Crystallography, 2015Co-Authors: Paramita Chatterjee, Samiran Pramanik, Alok K. MukherjeeAbstract:A combination of IR spectroscopy, scanning electron microscopy (SEM) and powder X-ray diffraction has been used to analyze the compositional and architectural variation across the different parts (core, middle and outer layers) of five human urinary calculi (KS1–KS5) from eastern India. Rietveld quantitative phase analysis using X-ray powder diffraction revealed that the composition of the core regions in KS1–KS3 and KS5 is exclusively Whewellite, whereas in KS4 it is a mixture of Whewellite (84.5 wt%) and carbonated hydroxyapatite (15.5 wt%). While one of the renal stones, KS1, is composed of only Whewellite in all three regions, a distinct variation in phase composition from the core towards the periphery has been observed in KS2–KS5. A drastic change in phase composition has been noted in KS5, with the major constituent phases in the core, middle and outer layers as Whewellite (100.0 wt%), anhydrous uric acid (60.7 wt%) and carbonated hydroxyapatite (69.6 wt%), respectively. The crystallite size of Whewellite in different parts of the kidney stones varies between 91 (1) and 167 (1) nm, while the corresponding sizes of the anhydrous uric acid in KS5 and carbonated hydroxyapatite in KS3 are 107 (1) and 18 (1)–20 (1) nm, respectively. SEM images of the kidney stones showed different levels of organization, resulting from an agglomeration of crystallites with diverse shapes and sizes.
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Structural and microstructural chracterization of seven human kidney stones using FTIR spectroscopy, SEM, thermal study and X-ray Rietveld analysis
Zeitschrift für Kristallographie - Crystalline Materials, 2014Co-Authors: Soumen Ghosh, Paramita Chatterjee, Abir Bhattacharya, Alok K. MukherjeeAbstract:AbstractStructural and microstructural parameters of seven kidney stones (UKS1–UKS7) retrieved from patients of eastern India were investigated using FTIR spectroscopy, scanning electron microscopy, thermogravimetric analysis and X-ray powder diffractometry. Quantitative phase analysis of kidney stones was performed following the Rietveld method. Crystallite sizes and thermal stability were evaluated from the X-ray peak-broadening analysis and thermogravimetric study. Rietveld analysis of X-ray powder diffraction data indicates that kidney stones are a mixture of phases with Whewellite as the major constituent in UKS1–UKS4 and UKS7, whereas the major phase in UKS5 and UKS6 is anhydrous uric acid. The crystallite size of Whewellite phase in stones with more than 50 wt% of Whewellite (UKS1-UKS4 and UKS7) varies from 149(5) to 182(1) nm, whereas the corresponding sizes of uric acid crystallites in stones with more than 50 wt% of uric acid (UKS5 and UKS6) are 163(2) and 190(3) nm, respectively. Thermogravimetric analysis (TG) of UKS1 reveals that Whewellite is stable upto 400 K and above this temperature anhydrous calcium oxalate is formed, which tranforms into calcium carbonate at 750 K and finally to calcium oxide above 970 K. The kidney stone UKS5 with more than 90 wt% of uric acid is stable upto 708 K.
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Human Kidney Stone Analysis using X-ray Powder Diffraction
Journal of the Indian Institute of Science, 2014Co-Authors: Alok K. MukherjeeAbstract:Physical and chemical methods available for kidney stone analysis are critically reviewed. Although various methods, such as the FTIR and Raman spectroscopy, scanning electron microscopy, thermogravimetry etc. can be used for qualitative phase analysis of kidney stones, the Rietveld method based on high quality X-ray powder diffraction data provides a precise and reliable technique for identifying the structure as well as the quantitative phase abundance of different crystalline components in human urinary calculi. Quantitative phase analyses of ten (10) kidney stones (KS1-KS10) from eastern India revealed that most of the calculi samples are mixture of phases with calcium oxalate monohydrate (Whewellite) as the major constituent and varying amounts of calcium oxalate dihydrate (weddellite), calcium hydroxyapatite, uric acid and ammonium acid urate. The crystal structures of Whewellite and weddellite have been redetermined using X-ray powder diffraction methodology.
Paramita Chatterjee - One of the best experts on this subject based on the ideXlab platform.
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Phase composition and morphological characterization of human kidney stones using IR spectroscopy, scanning electron microscopy and X-ray Rietveld analysis.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2018Co-Authors: Paramita Chatterjee, Arup Chakraborty, Alok K. MukherjeeAbstract:Abstract Pathological calcification in human urinary tract (kidney stones) is a common problem affecting an increasing number of people around the world. Analysis of such minerals or compounds is of fundamental importance for understanding their etiology and for the development of prophylactic measures. In the present study, structural characterization, phase quantification and morphological behaviour of thirty three (33) human kidney stones from eastern India have been carried out using IR spectroscopy (FT-IR), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Quantitative phase composition of kidney stones has been analyzed following the Rietveld method. Based on the quantitative estimates of constituent phases, the calculi samples have been classified into oxalate (OX), uric acid (UA), phosphate (PH) and mixed (MX) groups. Rietveld analysis of PXRD patterns showed that twelve (36%) of the renal calculi were composed exclusively of Whewellite (calcium oxalate monohydrate, COM). The remaining twenty one (64%) stones were mixture of phases with oxalate as the major constituent in fourteen (67%) of these stones. The average crystallite size of Whewellite in oxalate stones, as determined from the PXRD analysis, varies between 93 (1) nm and 202 (3) nm, whereas the corresponding sizes for the uric acid and struvite crystallites in UA and PH stones are 79 (1)–155 (4) nm and 69 (1)–123(1) nm, respectively. The size of hydroxyapatite crystallites, 10 (1)–21 (1) nm, is smaller by about one order of magnitude compared to other minerals in the kidney stones. A statistical analysis using fifty (50) kidney stones (33 calculi from the present study and 17 calculi reported earlier from our laboratory) revealed that the oxalate group (Whewellite, weddellite or mixture of Whewellite and weddellite as the major constituent) is the most prevalent (82%) kidney stone type in eastern India.
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Compositional and architectural variation in urinary calculi from nucleus to periphery: an integrated IR spectroscopy, scanning electron microscopy and powder X‐ray diffraction approach
Journal of Applied Crystallography, 2015Co-Authors: Paramita Chatterjee, Samiran Pramanik, Alok K. MukherjeeAbstract:A combination of IR spectroscopy, scanning electron microscopy (SEM) and powder X-ray diffraction has been used to analyze the compositional and architectural variation across the different parts (core, middle and outer layers) of five human urinary calculi (KS1–KS5) from eastern India. Rietveld quantitative phase analysis using X-ray powder diffraction revealed that the composition of the core regions in KS1–KS3 and KS5 is exclusively Whewellite, whereas in KS4 it is a mixture of Whewellite (84.5 wt%) and carbonated hydroxyapatite (15.5 wt%). While one of the renal stones, KS1, is composed of only Whewellite in all three regions, a distinct variation in phase composition from the core towards the periphery has been observed in KS2–KS5. A drastic change in phase composition has been noted in KS5, with the major constituent phases in the core, middle and outer layers as Whewellite (100.0 wt%), anhydrous uric acid (60.7 wt%) and carbonated hydroxyapatite (69.6 wt%), respectively. The crystallite size of Whewellite in different parts of the kidney stones varies between 91 (1) and 167 (1) nm, while the corresponding sizes of the anhydrous uric acid in KS5 and carbonated hydroxyapatite in KS3 are 107 (1) and 18 (1)–20 (1) nm, respectively. SEM images of the kidney stones showed different levels of organization, resulting from an agglomeration of crystallites with diverse shapes and sizes.
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Structural and microstructural chracterization of seven human kidney stones using FTIR spectroscopy, SEM, thermal study and X-ray Rietveld analysis
Zeitschrift für Kristallographie - Crystalline Materials, 2014Co-Authors: Soumen Ghosh, Paramita Chatterjee, Abir Bhattacharya, Alok K. MukherjeeAbstract:AbstractStructural and microstructural parameters of seven kidney stones (UKS1–UKS7) retrieved from patients of eastern India were investigated using FTIR spectroscopy, scanning electron microscopy, thermogravimetric analysis and X-ray powder diffractometry. Quantitative phase analysis of kidney stones was performed following the Rietveld method. Crystallite sizes and thermal stability were evaluated from the X-ray peak-broadening analysis and thermogravimetric study. Rietveld analysis of X-ray powder diffraction data indicates that kidney stones are a mixture of phases with Whewellite as the major constituent in UKS1–UKS4 and UKS7, whereas the major phase in UKS5 and UKS6 is anhydrous uric acid. The crystallite size of Whewellite phase in stones with more than 50 wt% of Whewellite (UKS1-UKS4 and UKS7) varies from 149(5) to 182(1) nm, whereas the corresponding sizes of uric acid crystallites in stones with more than 50 wt% of uric acid (UKS5 and UKS6) are 163(2) and 190(3) nm, respectively. Thermogravimetric analysis (TG) of UKS1 reveals that Whewellite is stable upto 400 K and above this temperature anhydrous calcium oxalate is formed, which tranforms into calcium carbonate at 750 K and finally to calcium oxide above 970 K. The kidney stone UKS5 with more than 90 wt% of uric acid is stable upto 708 K.
Roman Skála - One of the best experts on this subject based on the ideXlab platform.
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carbon isotopic composition of Whewellite cac2o4 h2o from different geological environments and its significance
Chemical Geology, 1993Co-Authors: K Zak, Roman SkálaAbstract:Carbon isotopic composition of Whewellite (CaC2O4·H2O) varies significantly among individual types of occurrences from the Bohemian Massif, Czech Republic. The δ13C-values of Whewellite found inside pelosiderite concretions in the coal-bearing Carboniferous Kladno Basin are unusually high from + 3.2 to + 14.7‰, indicating influence of bacterial activity on the oxalate carbon isotopic composition. In the Tertiary Northern Bohemian Basin, where the depth of burial and coalification grades are much lower, the δ13C-values of two Whewellite samples are − 6.9 and − 14.2‰. Whewellites from low-temperature hydrothermal veins of the Přibram uranium deposits, where bacterial processes are highly unlikely, have δ13C-values of − 31.7 to − 28.4‰, identical to carbon isotopic composition of underlying black shales.
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Carbon isotopic composition of Whewellite (CaC2O4·H2O) from different geological environments and its significance
Chemical Geology, 1993Co-Authors: K. Z̆ák, Roman SkálaAbstract:Carbon isotopic composition of Whewellite (CaC2O4·H2O) varies significantly among individual types of occurrences from the Bohemian Massif, Czech Republic. The δ13C-values of Whewellite found inside pelosiderite concretions in the coal-bearing Carboniferous Kladno Basin are unusually high from + 3.2 to + 14.7‰, indicating influence of bacterial activity on the oxalate carbon isotopic composition. In the Tertiary Northern Bohemian Basin, where the depth of burial and coalification grades are much lower, the δ13C-values of two Whewellite samples are − 6.9 and − 14.2‰. Whewellites from low-temperature hydrothermal veins of the Přibram uranium deposits, where bacterial processes are highly unlikely, have δ13C-values of − 31.7 to − 28.4‰, identical to carbon isotopic composition of underlying black shales.
