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Thermoanalytical investigations have been performed on lobster shell, its main components (chitin and protein) and the influence of the isolation procedure. The different peaks appearing during the thermal decomposition of lobster shell were identified, except for an endothermic peak at 220°. A hypothesis is suggested for the nature of this peak.

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The chemical composition and thermal behaviour of crab, shrimp and lobster shells were studied. The lobster cephalothorax and its main parts also constitute important sources of both polymers. Their chitin and protein content are 20 and 40 %, respectively (dry base) while in these cases the proteins are less associated to the matrix than in the carapace. The chitin level in the chitinous concentrates isolated from different sources is over 80 % in all cases but the polymer characteristics change in dependence on the raw material.

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Thermoanalytical studies on lobster shell

II. Quantitative analysis

Journal of Thermal Analysis and Calorimetry
Authors:
I. Garcia Alonso
and
D. Oviedo Vega

The chemical composition of lobster shells was determined by thermal analysis without previous sample preparation. The humidity and ash content were directly calculated from the TG curve. A correlation between the percentage weight loss is a particular temperature interval and the concentration of chitin and protein in the starting material was found, and based on this new method is proposed for the quantitative determination of both polymers. The residual protein after the deproteinization could be estimated with 0.3% error.

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A chitin-lipoprotein complex was detected in the pre-exuvial lobster shell. The aqueous extract of this skeleton contains a lipoprotein in its highest molecular weight fraction where the phospholipids constitute the main component. Changes in the lipoprotein crystalline structure with temperature were detected, but not the formation of typical liquid crystals.

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The aim of this research was to assess the total antioxidant activity (TAA) of lipophilic (Lextr) and hydrophilic (Hextr) tomato extracts using in vitro chemical tests and cell-based assays, focusing on possible synergistic actions between tomato antioxidants. Both Hextr and Lextr were HPLC analysed for their carotenoids, phenolic compounds, and ascorbic acid contents. For the evaluation of TAA, extracts were assayed alone or in combination using in vitro chemical tests (TEAC, FRAP) and cell-based (CAA) assays using human hepatoma (HepG2) and human histiocytic lymphoma (U937) cells. The only carotenoid detected in Lextr was lycopene, while a mixture of phenolic compounds (chlorogenic acid, caffeic acid, and rutin) was identified in Hextr. Ascorbic acid was not found either in Hextr or in Lextr. Upon extract combination (1:1, v/v), the FRAP assay revealed additive action between Lextr and Hextr, whilst a slight synergistic action was observed in TAA as measured by the TEAC assay. Synergistic action was better revealed when TAA was analysed using either U937 or HepG2 cells. This could be explained by the presence of a multiphase media (cell membrane and extra- and intracellular media) that might facilitate the distribution and interaction of antioxidants with different polarities and different mechanisms of action.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
J. Glatz
,
I. Garcia-Alonso
,
T. Kameyama
,
L. Koch
,
G. Pagliosa
,
T. Tsukada
, and
H. Yokoyama

Abstract  

In order to study the dissolution behavior of a highly burnt LWR fuel, a fuel pin irradiated in the DR3 test reactor in Risoe National Laboratory, has been characterized by microstructural examination and then dissolved under PUREX type conditions. The dissolution behavior was investigated and the residues analyzed by scanning electron microscopy and by ICP-MS and IDMS after dissolution.

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