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Journal of Thermal Analysis and Calorimetry
Authors:
R. Sridarane
,
G. Raje
,
D. Shanmukaraj
,
B. Kalaiselvi
,
M. Santhi
,
S. Subramanian
,
S. Mohan
,
B. Palanivel
, and
R. Murugan

Abstract  

The understanding of molecular level structural information of phosphate glasses is very much essential. The unique microwave-absorbing ability of NaH2PO4·2H2O was found to be very useful for preparing crystal and glassy sodium super ionic conductors (Nasicon's) as a component of batch mixtures. In this work NaPO3 glass was prepared by both conventional melt quench and microwave heating from NaH2PO4·2H2O as a starting material. The structure of NaPO3 glass and their structural evolution upon heating through glass transition were probed by combination of complementary techniques like differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) and thermo-Raman spectroscopy.

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The aim of the present summary is the spatial extension of the structural elements of the Vardar System into the inner areas of the Carpathian Basin and the evidence of its Paleogene and Neogene rejuvenations by the method of the paleogeographic reconstruction. Due to the spatial and temporal extension of the system, the concept is introduced into literature with the name of Neo-Vardar. In the present paper, its movements during the Neogene orogenic cycles, its significance in the development of the sedimentary cycles and spatial changes of the facies as well as its effects on the formation of the volcanic cycles are presented, and its determinant role in the formation of the Pannonian Basin and its sub-basins 14.5 million years ago as well as its predictive significance in the exploration of Neogene coal, hydrocarbon and ore deposits are proved.

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Introduction The Mecsekalja Zone is a ~1.5-km-wide strike-slip fault zone in South Transdanubia, Hungary (Fig.  1 ) that has been active since the Permian and that significantly controls the structural evolution of the adjacent

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Abstract  

Mixed oxides SiO2/SnO2 with 80/20 nominal weight composition have been obtained by the sol-gel method with different precursors. X-ray diffraction and low temperature transmission Mössbauer spectroscopy have been used to follow the structural evolution of the samples after treatments in the temperature range RT-1050 °C. The main results are that changes in the precursor nature and gel preparation affect the Sn(IV) homogeneity in the SiO2 matrix and that the use of Sn-alkoxides increases the content of residual carbon which promotes reduction of Sn(IV) at intermediate temperatures.

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Abstract  

In this article, we show that the crystallization behaviour of a rubber-filled polypropylene, under isothermal conditions, can be monitored by means of parallel plate rheometry and differential scanning calorimetry. Data collected with different instruments can be compared only after performance of accurate temperature calibration. The complex modulus as obtained from dynamic mechanical measurements can be related to the crystalline content by use of appropriate mathematical relationships. An empirical power law model is used to correlate the crystalline content to the rheological function. Excellent agreement between rheological and calorimetric data is found. Furthermore, it is shown that rheology can be used to achieve additional information on the structural evolution of the crystallizing system.

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Eperkés Hill is a thoroughly studied classic exposure, yet its facies interpretation is still debated. The issue is whether Upper Triassic - lowermost Jurassic carbonates are regular beds or blocks embedded within the Kimmeridgian-Berriasian limestone. The answer to this question is important for the interpretation of the structural evolution and paleogeography of the Transdanubian Range area at the Jurassic-Cretaceous boundary; we decided therefore to contribute to the solution by applying paleomagnetism to the problem.  We tested several regular beds and suspected olistoliths from two artificial exposures. In order to check the consistency of the paleomagnetic signal on site level, we drilled three or more cores from each, and subjected them to standard paleomagnetic laboratory processing and evaluation.  We found that magnetic parameters were distinctly different for "regular" beds and for suspected olistoliths, but that the paleomagnetic signal was consistent within every site. However, between-site consistency was extremely high for regular beds, but was non-existent for the "megabreccia" horizon. Thus, our results confirm that older limestone was moved and re-deposited during the Late Jurassic-Early Cretaceous, indicating geodynamic conditions similar to those in the Northern Calcareous Alps.

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A continuous Sarmatian/Pannonian boundary section, which rarely crops out within the Pannonian Basin, was studied near Oarba de Mures/Marosorbó. Alternating beds of clay marl, calcareous marl, siltstone, sandstone and andesitic tuff are present up to a thickness of about 100 m. Traditionally the Sa/Pa boundary was placed at the top of the last significant tuff layer, which has been confirmed by mollusk-bearing strata a few meters above belonging to the "Lymnocardium" praeponticum Zone. This zone is coeval with the Early Pannonian Mecsekia ultima dinoflagellate zone and the C5r magnetic polarity zone. Three ranks of cyclicity connected to sediment gravity flows are present in the outcrops. Coarse silt to sandstone beds were formed by low-density turbidity currents. These individual events represent "dilution cycles" connected to the intensity and abundance of turbidity currents. Turbiditic beds, some 2-5 m-thick series of sandstones, form coarsening/thickening upward cycles of 8-20 m of thickness. This cyclicity may reflect autocyclic lobe switching in deep lacustrine fans. The lowermost 70 m of the succession comprises a major thickening to thinning cycle, while the uppermost part of the sequence seems to represent a longer turbidite-free interval. The last may either reflect climatically-driven allocyclic lake-level variations or impulses of hinterland structural evolution (tectonic activity vs. quiescence). The background sediments show two sorts of seemingly independent rhythmicity: there is marl with variable carbonate content, occasionally forming a few cm of thickening-upward series of calcareous marl, and it also shows various grades of bioturbation. Calcareous marl is often associated with the appearance of fibrous gypsum laminae. The alternating carbonate content of the marl might be generated either by "production cycles" in the photic zone over which the climatic influence is straightforward, or they were formed as the first products of the evaporite succession from hypersaline bottom waters. The lack of bioturbation combined with gypsum may reveal hypersaline and/or dysaeroabic abiotic bottom conditions. These also indicate that turbidity currents had transported not only terrestrial sediments but less saline, O2-bearing water down to the lake floor, interrupting the biota-poor periods. The salinity of the bottom waters in the deepest basin segments might significantly differ from that of the main water mass, and might have been regulated by the composition and amount of ions dissolved from Mid-Miocene salt diapirs cropping out at the lake bottom elsewhere. Accumulation of hypersaline bottom waters may also be facilitated by climatically-determined density stratification of the lake water.

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Gyrfi, I. 1993: Structural evolution of the Neogene basins of SE Hungary and the Apuseni Mts. - Unpubl. M. Sc. Thesis Etvs University, Budapest (in Hung.). Hodges, K.V., P.D. Crowley 1985: Error estimation and

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Devos, K. M., Dubcovsky, J., Dvorak, J., Chinoy, C. N., Gale, M. D. (1995): Structural evolution of wheat chromosomes 4A, 5A, and 7B and its impact on recombination. Theor. Appl. Genet. , 91 , 282–288. Gale M

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