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Abstract  

The western region of the Deccan Volcanic Province (DVP) is constituted of tholeiitic lava flows. They host numerous cavities, varying in size and shape, largely occupied by zeolites and a variety of secondary minerals, amongst which the fibrous zeolites (natrolite group), are particularly gorgeous and attractive. Scolecite and mesolite are the only two members commonly occurring in this region. Our data on their thermal behaviour significantly differs from that reported in previous literature. Scolecite, Ca8(Al16Si24O80)·24H2O shows three distinct steps instead of two and water loss is observed even beyond 550°C. It is held that the first step corresponds to the expulsion of water from the site farthest away from Ca and the next two steps in succession correspond to the two sites nearer to Ca. Mesolite, Na16Ca16(Al48Si72O240)· 64H2O has much more complex behaviour with four or five steps of water expulsion and a major loss around 248–270°C in a double reaction attributed here to the expulsion of water from scolecite type channels. It is further held that the natrolite type channels are emptied in further steps. Loss of water in steps even beyond 400°C is particularly noted and such reactions are well reflected in the TG and the DTG. Peak temperature dependence on sample amounts is also evident. Successive phase transformations above 700°C, up to 1000°C are reflected in the DTA curves.

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Journal of Thermal Analysis and Calorimetry
Authors: Mihaela Badea, Rodica Olar, Dana Marinescu, Veronica Lazar, Carmen Chifiriuc, and Gina Vasile

Abstract  

This paper reports the investigation on the thermal stability of new complexes with mixed ligands of the type [Cd(NN)(C3H3O2)2(H2O)m]·nH2O [(1) NN: 1,10-phenantroline, m = 1, n = 0; (2) NN: 2,2′-bipyridine, m = 0, n = 1.5 and (C3H3O2): acrylate anion]. The IR data indicate a bidentate coordination mode for both heterocyclic amine and acrylate. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against planktonic as well as biofilm embedded Gram-negative (Escherichia coli, Klebsiella sp., Proteus sp., Salmonella sp., Shigella sp., Acinetobacter boumani, Pseudomonas aeruginosa), Gram-positive (Bacillus subtilis, Staphylococcus aureus) and fungal (Candida albicans) strains, reference and isolated ones from the hospital environment. The thermal behaviour steps were investigated in synthetic air flow. The thermal transformations are complex processes according to TG and DTA curves including dehydration, amine as well as acrylate thermolysis. The final products of decomposition are the most stable metal oxides.

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In this work the thermal characteristics of cellulose samples with different structure were investigated. The samples were prepared by reacting the cellulose with ethanolic hydroxide solution. Depending on the time of alkaline treatment, the intensity of cellulose transformation differed. Starting from cellulose I structure, with the highest degree of crystallinity, the other samples consisted of mixed structures of cellulose I and II, or were completely transformed to cellulose II structure with the lowest degree of crystallinity. The thermal behaviour of the samples was studied by using a Perkin Elmer TGS-2 and DSC-2 instruments. The kinetic parameters of dehydration and degradation were determined from non-isothermal TG-data (Nitrogen-inert atmosphere and a heating rate of 20 deg/min). The thermal effects of water evolution (heating rate of 80 deg/min) of the cellulose samples were found to depend on the structural characteristics and the crystallinity of the samples. The activation energy and frequency factor were in correlation with the structural changes.

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Thermal behaviour of mixed Sn and Ge phosphates

Correlations with their catalytic properties

Journal of Thermal Analysis and Calorimetry
Authors: A. La Ginestra, P. Patrono, A. Frezza, C. Mancini, M. Massucci, and S. Vecchio

Abstract  

Pure and mixed Ge and Sn hydrogenphosphates, prepared either by refluxing in 8M H3PO4 or by hydrothermal treatment at 180° or 300°C, have been characterized in terms of chemical composition and thermal behaviour and also tested as catalysts in the 1-butene isomerization, in order to correlate acidic properties with preparation method. Solid solutions for every composition in this system are formed only when using the refluxing method, as proved by X-ray and TG-DTA data. The hydrothermal treatments are strongly influenced by the hydrolysability of the Ge phosphate: in almost all the samples, where Ge was present, GeOHPO4 was identified on TG-DTA curves by the endothermic H2O weight loss at 700°–800°C. The acidic properties of the various materials decrease as GeOHPO4 content increases.

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The technique of heat flow calorimetry was used to study the thermal behaviour of different carbohydrates between 20°C and 270°C. The samples were analyzed by heating in sealed cells. The temperature range in which exothermic reactions, due to thermal decomposition, occurred varied widely depending on the type of carbohydrate investigated. Reaction enthalpies of 44 sugars and polysaccharides are given. Endothermic phenomena, such as fusion or vaporization of crystallized water, were also observed: fusion temperatures and enthalpies of 34 sugars and sugar alcohols are listed. Calorimetric curves showing crystallization of amorphous sucrose, cellobiose and lactose are also presented.

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Journal of Thermal Analysis and Calorimetry
Authors: Ramón Piloto Rodríguez, Leonardo Goyos Pérez, Marlen Alfonso, Milagros Duarte, Rinaldo Caro, Jonas Galle, Roger Sierens, and Sebastian Verhelst

tested in this paper will be named as derived FAEE, as ethanol was used in the chemical synthesis. The purpose of this study is to evaluate and compare the thermal behavior and oxidative stability of two different species and plantations of

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Journal of Thermal Analysis and Calorimetry
Authors: Katsumi Katoh, Shunsuke Ito, Shuhei Kawaguchi, Eiko Higashi, Katsuyuki Nakano, Yuji Ogata, and Yuji Wada

Abstract  

In the previous study, it was observed that the stability of nitrocellulose (NC) cannot be determined by thermal analyses such as differential scanning calorimetry (DSC) at heating rates of 1–10 K/min. This was because the thermal curves of NC samples with different stabilities could not be distinguished from one another. In this study, we explain why such thermal analyses cannot be used to evaluate the thermal stability of NC and identify the conditions under which thermal analyses can be used for this purpose. We investigated the effect of heating rate on the thermal behavior of pure NC and NC stabilized with diphenylamine (DPA) or akarditeII (AKII), which is a conventional stabilizer, by using the heat flux calorimeter (C80). At high heating rates (0.2–0.3 K/min), only single exothermic peak was observed in the thermal curves of both pure NC and NC/DPA and the thermal curve of pure NC was practically similar to that of NC/DPA. At low heating rate (0.02 K/min), two exothermic peaks were observed for both pure NC and NC/DPA. The heat amount of the first peak depended on the partial pressure of O2 in the atmosphere. The first peak in the thermal curve of NC/DPA was slightly suppressed as compared to that of pure NC. These results indicate that the stability of NC probably depends on the first exothermic peak that represents oxidation of NC by atmospheric O2. From this, on the thermal analyses at high heating rates, thermal curves of pure NC and NC/DPA could not be distinguished from one another. This is because the decomposition of NC itself occurs in the second exothermic peak before the oxidation of NC by atmospheric O2 in the first peak, which is attributed to the stability of NC. The results of the thermal analyses under isothermal conditions at 393 K in an O2 atmosphere revealed that the induction period of NC/DPA and NC/AKII was longer than that of pure NC. From these results, it is speculated that the stability of NC can be evaluated by thermal analyses carried out under O2-rich conditions at low heating rates.

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Journal of Thermal Analysis and Calorimetry
Authors: Renato Vessecchi Lourenço, Marcelo Kobelnik, Clóvis Augusto Ribeiro, and Fernando L. Fernonani

biocatalyst and sludge material to be processed due in large bacterial activity, allows a greater organic load and higher conversion rates of organic matter into biogas [ 7 ]. In this study, we report on the thermal behavior of the aerobic UASB and

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Journal of Thermal Analysis and Calorimetry
Authors: Marcelo Kobelnik, Douglas Lopes Cassimiro, Diógenes dos Santos Dias, Clóvis Augusto Ribeiro, and Marisa Spirandeli Crespi

. Recently, we evaluated the thermal characterization of jerivá oil, but were not observed the similar thermal behavior like here reported [ 9 ]. Nevertheless, the jerivá oil showed varied fatty acids composition, while the araça oil has predominantly only

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Journal of Thermal Analysis and Calorimetry
Authors: Marisa S. Crespi, Quézia V. Martins, Sonia de Almeida, Hernane S. Barud, Marcelo Kobelnik, and Clóvis A. Ribeiro

]. Here, we studied the first five, since some of them have great economic value and possible use as an energy source, or because of the higher potential for environmental pollution from the large amounts produced. We evaluated the thermal behavior of

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