scholarly journals Comparative Study on Thermodynamic and Geochemical Characteristics between Cemented and Clotted Parts of Thrombolite

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1017
Author(s):  
Dingxiang Zhuang ◽  
Yan Guo ◽  
Song Chen
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Carbon Isotope ◽  
Carbonate Rocks ◽  
Oil And Gas ◽  
Stable Carbon Isotope ◽  
Geochemical Characteristics ◽  
Stable Carbon ◽  
X Ray Diffraction ◽  
X Ray

Carbonate rocks are widely distributed in nature and are one of the main reservoir rocks for oil and gas. Microbes play an important role in the formation of carbonate rocks. Compared with the cemented part with fewer microorganisms (abiotic minerals), the nucleation and growth of the clotted part with more microorganisms (biotic minerals) are affected by the metabolic activities of microorganisms, so it has a unique morphology and crystal structure. However, there are still some confusing questions such as ones regarding the unique thermal decomposition characteristics and geochemical characteristics, which have rarely been studied. Here, X-ray diffraction (XRD) was used to determine the mineral composition of the cemented and clotted part in the same thrombolite. Then, thermal analysis and stable isotope geochemistry were used to explore the thermal stability and stable carbon isotope. The results of X-ray diffraction (XRD) show that the mineral components of the cemented and clotted part in the thrombolite are calcites, but their crystallinity is different. The crystallinity of the clotted part in the thrombolite is higher than that of the cemented part. Thermal analysis results show that the activation energy and the thermal stability of the clotted part in the thrombolite are relatively higher. In addition, the stable carbon isotope results show that, compared with the chemical precipitated calcite in the cemented part, the microorganisms in the clotted part absorb more 12C through photosynthesis, which results in more 13C in the clotted part, and the carbon isotope δ13C value is higher. This study helps to distinguish the crystallographic, thermodynamic and geochemical characteristics of cemented and clotted parts in thrombolite, and may be helpful to deepen our understanding of abiotic and biotic minerals.

Thermal Stability vs. Crystallization of the Lithiumsilicate Glasses with Addition Zirconium Dioxide and Titanium Dioxide

2008 ◽  
Vol 39-40 ◽  
pp. 399-401
Author(s):  
Viliam Pavlík ◽  
Eugen Jóna ◽  
Martina Sapietová ◽  
Soňa Šnircová
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Analysis ◽  
Titanium Dioxide ◽  
Differential Thermal Analysis ◽  
Structural Analysis ◽  
Zirconium Dioxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Relationship

The glasses with composition of Li2O . 2 SiO2 . n ZrO2 . n TiO2 (where n = 0; 0.015; 0.031; 0.050; 0.075; 0.1; 0.15; 0.2) were prepared and the relationship between structural and selected parameters of thermal stability vs. crystallization has been studied by differential thermal analysis. Structural analysis was provided by X–ray diffraction. The order of thermal stability vs. crystallization representing of activation energy of studied glass systems which increase with higher addition both oxides. The same order was obtained from the values of XRD. On the comparison the glasses with zero addition titanium dioxide their activation energy was much higher.

Amorphization of rapidly quenched quasicrystalline Al-transition metal alloys by the addition of Si

1986 ◽  
Vol 1 (3) ◽  
pp. 415-419 ◽  
Author(s):  
R.A. Dunlap ◽  
K. Dini
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Metal Alloys ◽  
Icosahedral Symmetry ◽  
Quench Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Metal Alloys ◽  
Rapidly Solidified ◽  
Thermal Stability Of

The structure and thermal stability of rapidly solidified Al-Cr-Si, Al-Mn-Si, Al-Fe-Si, Al-Co-Si, and Al-Ni-Si alloys have been investigated using x-ray diffraction and thermal analysis measurements. Each series of alloys shows a region of stoichiometry that yields icosahedral symmetry and a region that yields an amorphous phase. Thermal and structural properties of these alloys are reported as a function of stoichiometry and quench rate.

IDENTIFICATION OF PEDOGENIC CARBONATE MINERALS USING STABLE CARBON AND OXYGEN ISOTOPES, X-RAY DIFFRACTION AND SEM ANALYSES

1987 ◽  
Vol 67 (4) ◽  
pp. 953-958 ◽  
Author(s):  
J. J. MILLER ◽  
M. J. DUDAS ◽  
F. J. LONGSTAFFE
Keyword(s):  
Stable Carbon Isotope ◽  
Soil Samples ◽  
Bulk Soil ◽  
Stable Carbon ◽  
X Ray Diffraction ◽  
Carbonate Minerals ◽  
Carbon And Oxygen Isotopes ◽  
Pedogenic Carbonate ◽  
X Ray ◽  
O Isotope

A Cca and Ck horizon of an Orthic Regosol in Alberta were investigated using 13C/12C and 18O/16O isotope ratios, X-ray diffraction and the scanning electron microscope as a possible basis for differentiating pedogenic and lithogenic carbonate minerals Using the stable carbon-isotope method, the abundance of newly-formed pedogenic carbonate minerals in bulk soil samples of the Cca and Ck horizon was estimated to be 48 and 33% respectively. The δ18O values of carbonate minerals in bulk soil samples of the Cca and Ck horizon were −13.1 and −12.0‰, respectively. The presence of Mg-bearing pedogenic calcite in the sand and fine silt (2–10 μm) fractions of the Cca horizon were associated with soluble Mg2+/Ca2+ ratios of about two. Pedogenic carbonate minerals were visible as tiny equidimensional crystals about 0.1–0.6 μm in diameter, and as surface coatings on the sand-size, primary carbonate minerals in both horizons. These results may have a practical application in the use of ca and k suffixes in horizon designation. Key words: Pedogenic carbonate minerals, stable isotopes, Mg-bearing calcite, surface morphology

scholarly journals Study of structures and properties of ZnO-Sb2O3-P2O5-Na2O glasses

2014 ◽  
Vol 32 (3) ◽  
pp. 414-418 ◽  
Author(s):  
Yajun Qi ◽  
Zhiqiang Wang ◽  
Shangru Zhai ◽  
Shuwen Jiang ◽  
Hai Lin
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Weight Loss ◽  
Deionized Water ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Thermal Stability ◽  
Structures And Properties ◽  
Thermal Stability Of

AbstractThe influence of ZnO substitution by 0–12 wt.% Na2O on the properties of ZnO-Sb2O3-P2O5-Na2O glasses has been investigated. The structure and properties of the glasses with the composition of (13.86-x)ZnO-57.93Sb2O3-28.21P2O5−x Na2O (x = 0–12 wt.%) were characterized by infrared spectra (IR), X-ray diffraction and differential thermal analysis (DTA). The results of IR indicated an increase in the intensity of symmetric vibrations of P-O-P bond, which was confirmed by the improvement of water durability with the increasing amount of Na2O in the range of 0–10 wt.%. Substitution of 10 wt.% Na2O led to the weight loss of the glass to 5.93 mg/cm−2 after immersion in deionized water at 50 °C for 24 h. The results of XRD showed that the ability of crystallization decreased, indicating the good thermal stability of the glass. The glass containing 8 wt.% Na2O had the best properties in every respect and might be an alternative to lead based glasses for the applications, providing further composition improvement.

scholarly journals Biomineralization of Carbonate Minerals Induced by The Moderate Halophile Staphylococcus Warneri YXY2

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 58 ◽  
Author(s):  
Yu Han ◽  
Bin Sun ◽  
Huaxiao Yan ◽  
Maurice E. Tucker ◽  
Yanhong Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Isotope ◽  
Stable Carbon Isotope ◽  
Preferred Orientation ◽  
Dynamics Simulation ◽  
Stable Carbon ◽  
Carbonate Minerals ◽  
Moderate Halophile ◽  
X Ray ◽  
Staphylococcus Warneri

Although biomineralization of minerals induced by microorganisms has been widely reported, the mechanisms of biomineralization and the characteristics of the biominerals precipitated needs to be studied further. In this study, Staphylococcus warneri YXY2, a moderate halophile, was used to induce the precipitation of carbonate minerals at various Mg/Ca molar ratios. To investigate the biomineralization mechanism, the growth curve, pH changes, ammonia test, the concentration of bicarbonate and carbonate ions, and the activity of carbonic anhydrase (CA) and alkaline phosphatase (ALP) were determined. X-ray powder diffraction (XRD), scanning electron microscopy - energy disperse spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and stable carbon isotope analyses were used to characterize the minerals. The obtained biotic minerals were calcite, vaterite, Mg-rich calcite, and aragonite crystals. The crystallinity of aragonite decreased with increasing Mg/Ca ratios. The preferred orientation, diverse morphologies, organic substances, and more negative stable carbon isotope values proved the biogenesis of these carbonate minerals. The presence of Mg in the biotic aragonite crystals was likely related to the acidic amino acids which also facilitated the nucleation of minerals on/in the extracellular polymeric substances (EPS). Mg2+ and Ca2+ ions were able to enter into the YXY2 bacteria to induce intracellular biomineralization. Dynamics simulation using Material Studio software proved that different adsorption energies of Glutamic acid (Glu) adsorbed onto different crystal planes of aragonite led to the preferred orientation of aragonite. This study helps to deepen our understanding of biomineralization mechanisms and may be helpful to distinguish biotic minerals from abiotic minerals.

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