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. Cicerzynska , A. & Lenart , A. ( 2010 ): Rehydration and sorption properties of osmotically pretreated freeze-dried strawberries . J. Food Eng. , 97 , 267 – 274

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Abstract  

The rehydration characteristics of a commercially produced hydromagnesite and two basic magnesium carbonates synthetically produced from Mg(OH)2, are presented. The products were dehydrated and dehydroxylated at 325C before rehydration was attempted. DTA and FT-IR were used to follow the structural changes that occurred during the rehydration processes. The results obtained for the commercially and synthetically produced hydromagnesite products indicated that the original symmetry of the groups was reclaimed during rehydration. This was not observed for the synthetically produced unidentified basic magnesium carbonate product. This investigation provides insight into the rehydration characteristics of a select group of basic magnesium carbonates.

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Summary Magnesium oxide was produced through calcination of magnesite ore. A rehydration percentage of MgO to Mg(OH)2 of higher than 60% is obtained using calcination temperatures of 1000°C and below. At these temperatures medium reactive MgO was formed. The extend to which dead burnt MgO (obtained after calcination at 1200°C and higher) may be rehydrated is dependent on the calcination time, but even after 1 h and using magnesium acetate as a hydrating agent only 40% of the initial product has rehydrated to Mg(OH)2. After 4 and more hours of calcinations at 1200°C, a maximum of approximately 14% of the initial MgO is rehydrated back to Mg(OH)2. Thermogravimetric analysis was performed on the various compounds to determine the amounts of Mg(OH)2 that formed.

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Abstract  

The study of the dehydration/rehydration of ammonium tris-oxalato aluminate(III) (NH4)3Al(C2O4)3⋅3H2O in flowing dinitrogen saturated with water vapor at room temperature, using thermogravimetric analysis and X-ray diffraction techniques, allowed the determination of the temperature stability domains of (NH4)3Al(C2O4)3⋅3H2O, (NH4)3Al(C2O4)3⋅2H2O and the anhydrous salt. The X-ray powder diffraction profiles are reported for each of the three phases.

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than those of 100% Portland cement [ 3 ]. C. Alonso proved that after calcination at 750 °C, C–S–H gel transforms into a nesosilicate form with a C 2 S stoichiometry close to larnite, but less crystalline, and rehydration of the new generated

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pastes resistance to fire. To do it, the water of a normal consistency and the amount of water chemically combined through DTA analysis is determined [ 13 ]. The analysis of the dehydration and rehydration of cement pastes through thermal analysis

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. Sgherri , C. , Stevanovic , B. , Navari-Izzo , F. ( 2004 ) Role of phenolic acid during dehydration and rehydration of Ramonda serbica . Physiol. Plant. 122 , 478 – 485 . 38

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their metabolism upon rehydration ( Toldi et al., 2009 ). Desiccation-tolerant plants are capable of withstanding severe water loss to almost complete desiccation while maintaining some metabolic functions and maintaining the ability to quickly restore

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The study by thermal methods of the dehydration/rehydration phenomena of crystal hydrates shows that it is possible to separate the total heat of rehydration of previously dehydrated crystals into two contributions, attributed to surface and bulk, respectively. Values obtained for a number of salt hydrates are given and the ratio between the surface portion and the total heat is found to be of the order of 1%. Such findings are in agreement with results previously obtained by optical microscopy and are discussed in terms of recent views about the reversible reactions of crystalline solids.

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Pospíšilová, J., Batková, P. 2004. Effects of pre-treatments with abscisic acid and/or benzyladenine on gas exchange of French bean, sugar beet, and maize leaves during water stress and after rehydration. Biol. Plant. 48 :395

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