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Key indicatorsSingle-crystal X-ray study T = 293 K Mean '(C±C) = 0.006 A Ê R factor = 0.034 wR factor = 0.092 Data-to-parameter ratio = 6.2 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2004 International Union of Crystallography Printed in Great Britain ± all rights reserved The Cu atom of the title compound, [Cu(C 4 H 7 N 2 O 3 ) 2 ], is in a tetragonally distorted octahedral environment. A carboxyl O atom and the -amino N atom from each ligand coordinate to Cu in a trans square-planar con®guration [CuÐO = 2.003 (3) and 2.020 (3) A Ê , and CuÐN = 2.029 (4) and 2.049 (4) A Ê ]. The octahedron is completed by bridging amide O atoms from adjacent molecules [CuÐO = 2.229 (4) A Ê and CuÐO = 2.885 (4) A Ê ] separated by c translations. This arrangement creates in®nite chains linked in the [001] direction, stabilized by intra-and intermolecular NÐHÁ Á ÁO bonds. The structure has already been published [Stephens, Vagg & Williams (1975). Acta Cryst. B31, 841±845]; this redetermination reports the structure with higher precision.

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The elastic cartilage is composed by chondroblasts and chondrocytes, extracellular matrix and surrounded by perichondrium. It has a low regeneration capacity and is a challenge in surgical repair. One of obstacles in engineering a structurally sound and long-lasting tissue is selecting the most appropriate scaffold material. One of the techniques for obtaining biomaterials from animal tissues is the decellularization that decreases antigenicity. In this work, alkaline solution was used in bovine ear elastic cartilages to evaluate the decellularization and the architecture of the extracellular matrix. The cartilages were treated in alkaline solution (pH13) for 72 hours and lyophilized to be compared with untreated cartilages by histological analysis (hematoxylin-eosin, Masson's trichrome and Verhoeff slides). Areas of interest for cell counting and elastic fiber quantification were delineated, and the distribution of collagen and elastic fibers and the presence of non-fibrous proteins were observed. The results demonstrated that the alkaline solution caused 90% decellularization in the middle and 13% in the peripheral region, and maintenance of the histological characteristics of the collagen and elastic fibers and non-fibrous protein removal. It was concluded that the alkaline solution was efficient in the decellularization and removal of non-fibrous proteins from the elastic cartilages of the bovine ear.

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In recent years, the increase of economic and environmental problems related to energy generation has increased researches at renewable energy sources. Among others, the fuel cells excel as promising alternative technology of electricity generation and materials science is an ally in the search for better and more efficient materials for this application. In particular, solid-state ionic conductors represent functional materials with promising advantages for fuel cells, as is the case of Bi2O3-based oxygen ion conductors, however, they need to have its cubic phase stabilized at room temperature. This paper presents a study of the Bi6Te2-xRxO13 (R = Ti, Si and Ce) systems for such an application. Solid state reaction was used to materials synthesis. The 3Bi2O3:2TeO2 system present two phases, an orthorhombic one (Bi6Te2O15) stable at room temperature and another high temperature cubic (Bi6Te2O13). Experiments of substitution of Te ions by Ti, Si and Ce ions using the Bi6Te2- xRxO13 matrix were done intending to stabilize the cubic phase at room temperature and the results are presented as well as discussed here