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The coordination of research though this Action will lead to the development of new areas of fundamental scientific research due to the sharing of knowledge and enhancing the research abilities of the participants. The Action will coordinate research that will have significant impacts on important contemporary issues including the conservation and sustainable use of freshwater and marine ecosystems through using organisms as sentinels in biomonitoring and mimicking bio-inorganic processes to create new functional materials. The knowledge derived and disseminated under this Action will have strong socio-economic impacts. with applications in diverse areas such as information and communications technology, medical osseo-inclusion and dentistry.

Plant biominerals are not always well characterized, although this information is important for plant physiology and can be useful for taxonomic purposes. In this work, fresh plant material of seven wild neotropical species of genus Canna, C. ascendens, C. coccinea, C. indica, C. glauca, C. plurituberosa, C. variegatifolia and C. fuchsina sp. ined., taken from different habitats, were studied to characterize the biominerals in their internal tissues. For the first time, samples from primary and secondary veins of leaves were investigated by means of infrared spectroscopy, complemented with X-ray powder diffractometry and scanning electron microscopy. The spectroscopic results, supported by X-ray powder diffractometry, suggest that the calcium oxalate is present in the form of whewellite (CaC2O4×H2O) in all the investigated samples. It is interesting to emphasize that all IR spectra obtained were strongly similar in all species studied, thus indicating an identical chemical composition in terms of the biominerals found. In this sense, the results suggest that the species of Canna show similar ability to produce biogenic silica and produce an identical type of calcium oxalate within their tissues. These results can be an additional trait to support the relationship among the families of Zingiberales., Laboratorio de Estudios de Anatomía Vegetal Evolutiva y Sistemática, Centro de Química Inorgánica

INTRODUÇÃO: Otólitos são concrescências calcárias presentes no ouvido interno de peixes. Por serem ricos em minerais considerados essenciais ao processo de mineralização óssea sobre uma matriz proteica (otolina), sugere-se que otólitos poderiam funcionar como biominerais. OBJETIVO: Avaliar a capacidade de regeneração de defeitos ósseos tratados com preparado gelatinoso estéril de otólitos. MATERIAL E MÉTODO: O experimento foi realizado com 20 ratos Wistar, distribuídos aleatoriamente em dois grupos, nos quais se realizou defeito ósseo na tíbia, sendo o grupo 1 (G1) experimental, cujas lojas ósseas foram preenchidas com preparado de otólitos, e o grupo 2 (G2) controle, cujas lojas ósseas não receberam tratamento adicional. Os animais foram sacrificados 14 dias após os procedimentos cirúrgicos; as tíbias foram removidas, fixadas em formalina a 10%, descalcificadas em ácido nítrico a 5% e processadas histologicamente. Antes dos sacrifícios, foram coletadas amostras sanguíneas para avaliação das dosagens séricas de cálcio (Ca) e fosfatase alcalina (Alkp). RESULTADOS: As secções histológicas revelaram que o trabeculado ósseo neoformado mostrou-se mais denso e com atividade osteorreabsortiva periosteal menos conspícua no grupo experimental. Entretanto, não demonstraram diferenças estatisticamente significativas na área de neoformação óssea entre G1 (1,9 ± 0,3 mm²) e G2 (1,5 ± 0,4 mm²) (p = 0,0617). Os parâmetros bioquímicos (Ca e Alkp) apresentaram-se dentro dos limites de normalidade. DISCUSSÃO/CONCLUSÃO: Os dados sugerem que os otólitos podem desempenhar papel adjuvante na dinâmica da regeneração óssea. INTRODUCTION: Otoliths are calcareous concrescences present in the inner ear of fishes. Since they are rich in minerals considered essential to the bone mineralization process on a protein matrix (otolin), it has been suggested that otoliths may work as biominerals. OBJECTIVE: The objective in this study was to analyze the regeneration capacity of bone defects treated with sterile gelatinous otolith preparation. MATERIAL AND METHOD: The experiment was performed with 20 Wistar rats randomized into two groups, in which a bone defect was inflicted in the tibia. In group 1 (experimental), bone cavities were filled with otoliths. In group 2 (control), bone cavities did not receive any additional treatment. The animals were sacrificed 14 days after surgical procedures. The tibias were removed, fixed in formalin at 10%, decalcified in nitric acid at 5% and histologically processed. Before sacrifice, blood samples were collected to evaluate serum dosage of calcium (Ca2+) and alkaline phosphatase (Alkp). RESULTS: Histological sections revealed that the newly formed trabecular bone was denser and the periosteal reabsorptive activity was less conspicuous in the experimental group. However, there was no statistically significant difference in the area of bone formation between G1 (1.9 ± 0.3 mm²) and G2 (1.5 ± 0.4 mm²) (p = 0.0617). Biochemical (Ca2+ and Alkp) parameters were within normal range. DISCUSSION/CONCLUSION: These data suggest that otoliths may be an adjuvant to the dynamics of bone regeneration.

International audience; The crystal structures of biogenic Mn oxides produced by three fungal strains isolated from stream pebbles were determined using chemical analyses, XANES and EXAFS spectroscopy, and powder X-ray diffraction. The fungi-mediated oxidation of aqueous Mn2+ produces layered Mn oxides analogous to vernadite, a natural nanostructured and turbostratic variety of birnessite. The crystallites have domain dimensions of ~10 nm in the layer plane (equivalent to ~35 MnO6 octahedra), and ~1.5-2.2 nm perpendicularly (equivalent to ~2-3 layers), on average. The layers have hexagonal symmetry and from 22 to 30% vacant octahedral sites. This proportion likely includes edge sites, given the extremely small lateral size of the layers. The layer charge deficit, resulting from the missing layer Mn4+ cations, is balanced mainly by interlayer Mn3+ cations in triple-corner sharing position above and/or below vacant layer octahedra. The high surface area, defective crystal structure, and mixed Mn valence confer to these bio-minerals an extremely high chemical reactivity. They serve in the environment as sorption substrate for trace elements and possess catalytic redox properties.

Calcium oxalate druses were isolated from the stems and leaves of six Pereskioideae family members and investigated by infrared spectroscopy, showing that in all samples the biomineral was present in the form of whewellite, CaC2O4 · H2O. As Pereskia is thought to represent the “ancestral” condition of the leafl ess stem-succulent cacti, these results suggest that the biomineralization of calcium oxalate in Cactaceae represents a primitive characteristic of the group and also support a close genetic relationship between Pereskia and Opuntia., Publicado on line en 2014., Centro de Química Inorgánica

Vernadite is a nanocrystalline phyllomanganate ubiquist in nature and exhibiting a turbostratic stacking, that is systematic random stacking faults between adjacent layers. The presence of layer vacancies and/or of manganese cations with mixed oxidation states induces a strong deficit of charge, balanced by the presence of hydrated interlayer cations. These features provide vernadite with cation adsorption capacities, and/or redox potential that are responsible for its reactivity in superficial environments where it strongly influences the fate of numerous organic and metallic pollutants. Despite this role, the structures of vernadite and of its synthetic analogue delta-MnO2 are still incompletely determined as their structural disorder precludes the use of common structure refinement methods. We have thus applied a specific approach, coupled both with chemical and synchrotron-based spectroscopic (XANES and EXAFS) techniques, to determine the structures of delta-MnO2 and of vernadites produced by freshwater fungi together with the structural features responsible for their reactivity. The structure of delta-MnO2 evolves with pH and time with a strong potential influence on its reactivity. Structural mechanisms of adsorption of model metals (Ni and Zn) on delta-MnO2 were also determined. Adsorption occurs mainly above/below vacant layer sites, adsorption mechanisms being dependent on the metal and on the actual structure of delta-MnO2, La vernadite est un phyllomanganate nanocristallin présentant un empilement de feuillets turbostratique, c'est à dire des fautes d'empilement aléatoire systématiques entre deux feuillets successifs. La présence de lacunes foliaires et/ou de manganèse hétérovalent dans le feuillet induit un déficit de charge compensé par la présence de cations interfoliaires hydratés. Ces caractéristiques confèrent à la vernadite des propriétés d'adsorption et/ou un potentiel redox à l'origine de sa réactivité dans l'Environnement, où, en tant que phase ubiquiste, elle joue un rôle majeur pour le devenir de nombreux polluants organiques et métalliques. Malgré ce rôle, sa structure et celle de son analogue delta-MnO2 sont encore mal connues car leur désordre structural ne permet pas d'utiliser les techniques classiques d'affinement. Nous avons donc appliqué une approche spécifique, couplée à des méthodes chimiques et des mesures spectroscopiques (EXAFS et XANES), pour déterminer la structure d'échantillons de delta-MnO2 et de vernadites produites par des champignons ainsi que l'origine de leur réactivité. Nous avons également montré que la structure de delta-MnO2 évolue en fonction des conditions de pH et avec le temps, avec un impact fort sur sa réactivité. Nous avons enfin déterminé les mécanismes d'adsorption de métaux modèles (Ni et Zn) sur delta-MnO2. L'adsorption se fait majoritairement à l'aplomb de lacunes foliaires, les mécanismes d'asorption dépendant de la structure initiale de delat-MnO2 et du métal.

International audience; Mollusc shells are acellular biominerals, in which macromolecular structures are intimately associated with mineral phases. Most studies are devoted to proteins, despite sugars have been described. Lipids were extracted from the calcite prismatic and aragonite nacreous layer of two mollusc shells. Fourier Transform Infrared Spectrometry shows that lipids are present in both samples, but they are not similar. Thin layer chromatography confirms that lipids are different in the two studied layers, so that it may be suggested they are species-dependant. Although not yet deciphered, their role in biomineralization and fossilisation processes is probably important.

7 pages; International audience; To build their shells, brachiopods secrete a mixture of proteins and polysaccharides, collectively called the organic matrix. This matrix mediates the calcification process by allowing crystal nucleation followed by elongation and finally by stopping the crystal growth. Ultimately, the matrix controls the different microstructures formed. Brachiopod shells are composites with both organic and inorganic constituents intimately associated. This work represents an attempt to characterize the matrices using two combined approaches: (1) scanning electron microscopy for localization within the shell, (2) analysing extracted matrices at the molecular level to determine their biochemical properties. Representatives of the three terebratulid brachiopod genera: Gryphus , Liothyrella and Neothyris , were observed according to a standard procedure highlighting the microstructural details. Additionally, the acetic acid-soluble shell matrices were extracted and analyzed by sodium dodecyl polyacrylamide gel electrophoresis. Gels were subsequently stained with silver, Alcian blue and carbocyanine. In addition, the shell matrices were tested for their ability to bind calcium. Finally, functional in vitro assays were performed to check for the first time the effect of some of the shell matrices on calcium carbonate precipitation. Results show that the three matrices are extremely minor components ( < 0.05 wt %) of the shell and that the three genera exhibit some similarities in the electrophoretic patterns of their soluble matrices. Furthermore, the tested matrices drastically modify the morphology of calcite crystals in vitro. Putative similarities between brachiopod and molluscan shell matrices are discussed, as well as the early diagenesis effect that may affect brachiopod matrices.

International audience; The precise understanding of diagenetic pathways occurring during fossilization of biomineralized skeletons is of critical importance for various related fields in both paleontology and sedimentology. In particular, this may have fundamental implications in paleoenvironmental studies for interpreting geochemical proxies extracted from these skeletons. The effects of the first diagenetic processes on both mineral and organic compounds present in skeletons of scleractinian corals were investigated in two different coral colonies (Lobophyllia corymbosa and Leptastraea purpurea) by combining mapping of skeletal ultrastructural patterns by SEM and in situ analysis by Raman microspectroscopy. The two elementary ultrastructural features typical of scleractinian corals, the centers of calcification and the sets of aragonite fibers, have been characterized in the uppermost parts (i.e. the ‘‘living zone'') of both coral colonies. Diagenetic features affecting the skeleton itself and also represented by fibrous diagenetic cements have been analyzed in the oldest basal parts of each colony. All Raman spectra display several vibrational bands typical of aragonite (but no calcite). Additionally, several Raman bands indicate the presence of organic compounds, some of which likely characterize proteinous components, and provide the first in situ chemical record of the skeletal organic matrices. Tentative assignments to CH, CH2, CH3, NH2, CHO, CNC, and SO groups are proposed. In the ‘‘living zone,'' some of these bands are different in the two coral species. In Raman spectra measured in the oldest skeletal parts of both colonies, these bands decrease markedly in number and diversity or even disappear, indicating that significant decay of intraskeletal organic matrices does occur in just a few years. Therefore, early diagenesis in these skeletons results from the interaction between the degradation of organic matrices and the diagenetic processes affecting the skeletal aragonite submicron-size crystals.

International audience; Due to its particular mode of growth, the coral skeleton provides a natural model for evaluating the successive stages of diagenesis in a still-living organism. The spatial distribution of skeletal organic matrices and their early diagenesis have been investigated in a scleractinian skeleton with in situ micron-scale analyses by Raman Microspectroscopy. Results indicate that the decay of the organic matrices occurs within a few years. We suggest that the gradual deterioration of the skeletal organic matrices is a keymechanism driving earliest diagenesis in coral skeletons and represents the starting-point of the process of fossilization.

Various mineral cations (Ca^2+, Mg^2+, Na^+, Zn^2+) and anions (phosphate, oxalate, urate ions) can form biominerals which constitute normal (bone, teeth, shells) and pathological mineralized tissues (stones, caries, gouty arthritis, arteriosclerosis) in human body, plants and animals. The formation of biominerals, interpreted in a simple way, is the formation of sparingly soluble salts from body fluids (blood, serum, urine) within an organic macromolecular matrix. Processes involved in pathological mineralization are of special interest due to the great medical and social problems that they cause. In this work, the formation of compounds, frequently found in urinary calculi, calcium oxalate monohydrate (COM) and/or calcium oxalate dihydrate (COD), phosphate (e.g. calcium hydrogen phosphate dihydrate (DCPD)), uric acid (H_2U) and magnesium ammonium phosphate hexahydrate – struvite (S) and/or magnesium hydrogen phosphate trihydrate – newberyite (N), was studied in the model systems at physiological conditions (pH, ionic strength, initial reactant concentrations, temperature). The precipitates obtained were characterized by FT-IR spectroscopy, X-ray diffractometry and light microscopy. Their composition and morphology were compared with the crystals formed in urine. Figure 1 compares typical morphologies of calcium oxalate (a and a1), calcium phosphate (b and b1), uric acid (c and c1) and struvite (d and d1) formed in model systems (a-d) and in urine, (a1-d1). The investigations demonstrated that the composition and morphology of the crystals formed in all model systems were extremely sensitive to the precipitation conditions (composition and temperature of the mother liquid, the way of mixing the reactants, pH, ionic strength etc.). The presence of variety of crystal composition and habit in human urine (crystalluria) was compared with the urine biochemical parameters and composition of calculi. It is not possible to identify the stone-formers on the basis of crystalluria only. Reference: 1. A. Hesse, D. Heimbach ; World J Urol 17: 308-315, 1999

In the following article studies pertaining to "in situ" interactions of growing biogenic crystals (calcium phosphates, carbonates and oxalates) with, soluble, surface active molecules, including small, highly charged organic molecules, natural and synthetic polymers and synthetic surfactants, are discussed. Such interactions are at the roots of crystallization processes occurring in nature (biological mineralization) and in the controlled production of materials with well defined crystal structure, morphology and phase composition. The main characteristics of the crystals, including crystallographic data, and of the organic molecules, including their molecular structures, are briefly described. Most of the model crystals are crystal hydrates, whose dominant crystal planes are covered with continuous layers of structural water molecules (hydrated layer). The experimental methods reviewed include kinetic experiments determining induction times and/or the rates and rate controlling mechanisms of seeded and unseeded crystallization, techniques for the characterization of the nascent solid phase(s), and techniques, suitable for the assessment of interactions on the molecular level. Numerous examples show that the dominant mechanism underlying host crystal/additive interactions is selective adsorption of the additive at the crystal/solution interface, with the main driving forces ranging from purely electrostatic to highly specific recognition of crystal faces by the additive. Selective electrostatic interactions take place between growing crystals and flexible, highly charged small and macromolecules and/or surfactants because of differing ionic structures and charges of the crystal planes, some of them being shielded by hydrated layers. As in solution, surfactant molecules at high concentrations self-assemble into various superstructures (hemimicelles, bilayers) at the crystal/solution interface. Recognition of crystal planes by rigid small molecules and macromolecules with partial beta-sheet conformation (such as proteins or polyelectrolytes) is highly specific. It requires a dimensional fit between the distances of constituent ions protruding from the affected crystal plane(s) and the distances between functional groups that are part of the additive molecules. The consequences of selective additive/crystal interactions range from changes in crystal growth morphology to changes in the composition of the crystallizing phase. Examples showing the dual role of macromolecules as initiators and retarders of crystallization are discussed.

International audience; Early diagenetic changes occurring in aragonite coral skeletons were characterized at the micro- and ultrastructural scales in living and fossil scleractinian colonies, the latter of Pleistocene age. The skeleton of scleractinian corals, like all biomineralized structures, is a composite material formed by the intimate association of inorganic aragonite crystallites and organic matrices. In addition to its organo-mineral duality, the scleractinian skeleton is formed by the three-dimensional arrangement of two clearly distinct basic structural features, the centers of calcification and the fibers. The latter are typically characterized by a transverse micron-scale zonation revealing their incremental growth process. The size, geometry and three-dimensional arrangement of calcification centers and fibers are taxon-specific. The earliest diagenetic modifications of these skeletons have been clearly recognized in the older parts of living colonies. The first steps of diagenesis therefore take place only a few years after the skeleton had been secreted by the living polyps, and in the same environmental conditions. Comparisons with the uppermost living parts of the coral colonies clearly show that these first diagenetic changes are driven by the biological ultrastructural characteristics of these skeletons and are conditioned by the presence of organic envelopes interbedded with and surrounding aragonite crystallites. These first diagenetic processes induce the development of thin fringes of fibrous aragonite cements growing syntaxially on the aragonitic coral fibers, an alteration of the incremental zonation of coral fibers and also preferential diagenetic changes in the calcification centers, including dissolution of their minute internal crystals. Diagenetic patterns observed in Pleistocene coral colonies typically involve the same processes already recognized in the older skeletal parts of living colonies, suggesting that diagenesis occurs through continuous processes instead of clearly differentiated stages. Selective dissolution affects calcification centers and some growth increments of coral fibers. Alteration of the initial transverse zonation of coral fibers also occur through the development of micro-inclusions clearly seen in ultra-thin sections. Although usually thicker than those observed in the ancient skeletal parts of living colonies, syntaxial aragonite cements commonly occur in these fossil skeletons. These cements are often associated with gradual textural modifications of the underlying coral fibers, in particular the loss of the transverse micron-scale zonation. This suggests that the coral skeleton forming the substratum of diagenetic cements is progressively recrystallized in secondary aragonite. This recrystallization of coral aragonite begins at the external margin of the skeleton, just below the diagenetic cements and gradually moves towards the internal skeletal parts. Recrystallization takes place through concomitant fine-scale dissolution-precipitation processes and occurs with textural changes but no mineralogical change. The process of recrystallization is likely initiated by a biological degradation of organic skeletal matrices and can be also driven by thermodynamical constraints involving the lowering of surface free energies resulting from changes in crystal size. Alteration of skeletal organic matrix, textural changes in coral biocrystals through recrystallization and precipitation of secondary diagenetic aragonite may bias the original geochemical characteristics of coral skeletons. Although more work is needed to establish the influence of these early diagenetic processes on the geochemical signatures, it is already well known that the breakdown of organic skeletal envelopes and early recrystallization of shallow-water carbonates alter the stable isotopic composition. The widespread use of coral skeletons as environmental and climatic proxies makes strongly necessary a better understanding of these early diagenetic mechanisms and a precise characterization of the fine-scale diagenetic patterns of specimens for the optimization of geochemical interpretations. In particular, it cannot be assumed that an entire aragonitic composition can guarantee that there is no or slight diagenetic alteration.

Living creatures may deposit-precipitate biominerals in different ways, in a great variety of forms, shapes, orientations and with diverse functions. It is known that organisms from 55 distinctive phyla (from most primitive bacteria to the mammalian) can form more than 60 diverse biominerals Also it is known that calcium minerals represent about 50% of all biogenic minerals in the form of carbonates, sulfates, or phosphates. Other groups are iron containing sulfates and iron oxides and silica biominerals [1, 2, 3, 4]. In these research production of gypsum, barite, dolomite and another minerals never before recorded in Phylum Mollusca was described. Adult mussels Mytilus edulis sampled from the rocky shore of the Isle of Helgoland (North Sea, Germany) were induced to spawn by mechanical, thermal and chemical stimulation. Fertilized eggs were cultivated under controlled conditions for 80 hours, up to a developed veliger stage. Samples were taken every two hours after fertilization. Changes in morphology were observed by optical microscopy. Mineral components and phase fractions were determined using qualitative and quantitative X-ray diffraction. Diffraction patterns show that in the case where spawning was induced by barium chloride, the mineral composition of the larval shells were different from that where stimulation was mechanical, thermal or by other chemical compounds. The larvae contain in their prodissoconch I and prodissoconch II shells minerals as gypsum, barite, dolomite, halite and an unidentified phase in fractions from traces up to 20 molar %. However larvae were morphologically similar to the larvae with "normal " biominerals in the shells, i.e. calcite and aragonite [5]. Although in these research and generally, many aspects of early molluscan biomineralization and shell formation yet remain unexplained, possibilities to using mussels larvae like new biominerals producers are discussed. References [1] Lowenstam HA. Minerals formed by organisms. Science NY 1981 ; 211:1126-1131. [2] Addadi L, Berman A, Moradian OL, Weiner S. Structural and stereochemical relations between acidic macromolecules of organic matrices and crystals. Connect Tissue Res 1989 ; 21:127-135. [3] Mann S. Biomineralization: a novel approach to crystal engineering. Endeavour (New Ser) 1991 ; 15(3):120-125. [4] Webb J, Evans LA, St.Pierre TG, Macey DJ. Biominerals - source and inspiration for novel advanced materials. Search, Sydney 1991 ; 22(4):137-139. [5] Medaković D. Carbonic anhydrase activity and biomineralization process in embryos, larvae and adult blue mussels Mytilus edulis L. Helgol Mar Res 2000 ; 54:1-6.

International audience

La presencia de depósitos minerales es muy común en microorganismos, plantas, hongos y mamíferos. Estos organismos son, por lo tanto, un modelo natural excelente para estudiar la relación entre las principales partes que los componen, es decir la fase biopolímérica y la mineral. La importancia de este tipo de estudios se relaciona directamente con la nanotecnología, una rama científica relativamente reciente, encargada de estudiar los fenómenos químicos y físicos a escalas menores a los 500 nm. Cuando el sistema de estudio tiene importancia biológica, posee estructuras biológicamente activas o procede de un sistema biológico, se llama entonces bionanotecnología. Este es el caso del estudio de la biomineralización en las algas diatomeas. Esta línea de investigación tiene alta relevancia por la dificultad de producir micro y nanoestructuras altamente controladas de dióxido de silicio o sílice (SiO2), un tipo de vidrio que tiene potencialmente aplicaciones tecnológicas en liberación de drogas, celdas solares y materiales cerámicos de alto rendimiento. Los factores que afectan la geometría, las propiedades mecánicas y fisicoquímicas en estas estructuras son pobremente comprendidos, por lo que este tipo de estudios es de suma importancia. Si se logra entender las interacciones y los procesos de formación en estos sistemas que producen vidrio en entes biológicos, podremos acercarnos racionalmente a la síntesis de nuevos y sofisticados materiales nanoestructurados, con aplicaciones en una gran gama de áreas que van desde la nanotecnología (semiconductores híbridos) hasta la biología y biomedicina (biomateriales y estructuras liberadoras de drogas). En el presente trabajo se hace un esbozo “ascendente” (bottomup) de la síntesis de “biosilice” en diatomeas donde se enfatiza la importancia de este fenómeno en la nanotecnología. The presence of mineral deposition is very common in microorganisms, plants, mushrooms and mammals. This organisms are an excellent natural model to study the relation between the principal parts involved in the process, the biopolymeric and mineral phases. The importance of this kind of studies is the relation with nanotechnology. Being a relatively new science, nanotechnology studies the chemical and physical phenomena is a scale under the 500 nanometers. When the system under study has a biological significance, with active biologic structures, the term bionanotechnology is used. This is the case of the study of the biomineralization in diatomeas seaweed. Due to the difficulty in the production of controlled micro and nanostructures containing silica (SiO2), this study is relevant. The possible technological applications of this kind of crystals are drug liberation structures, photovoltaic cells and high performance ceramic materials. Factors that affect the geometry, mechanical and physicochemical properties are poorly understood, whereby this kind of studies are important. Understanding the interactions and processes involved in the production of biological crystals could yield to a rational production of new and sophisticated nanostructured material with a broad application in nanotechnology (hybrid semiconductors), biology and biomedicime (biomaterials, drug liberation structures). In the work we establish a “bottom up” draft of the synthesis of “biosilica” by diatomeas emphasizing the impact in nanotechnology.

Structural features of some calcium phosphates of biological interest are described. Structure of hydroxyapatite (OHAp), considered as the prototype for the inorganic component of bones and teeth is discussed with respect to the kinds and locations of ionic substitutions. Octacalcium phosphate (OCP), is a probable precursor in biological mineralization. OCP has a layer type structure, with one layer quite similar to that of OHAp and the other, a hydrated layer consisting of more widely spaced Ca, and PO4 ions and the water molecules. The closeness of fit in the apatitic layers of OCP and OHAp accounts for the epitaxial, interlayered mixtures formed by these compounds and the in situ conversion of OCP to OHAp. Possible roles of OCP in biological mineralization are discussed.

This paper presents an overview of the study of the ultrastructure of biogenic inorganic solids (biominerals) using high resolution transmission electron microscopy (HRTEM). A range of biominerals have been studied including iron oxides, calcium phosphates, calcium carbonates and silica. The studies have revealed information concerning the structural complexity of these materials and have identified crystallographic order and disorder at the nanometre level. In addition, the results have aided the elucidation of the mechanisms of nucleation and growth of biogenic minerals.

The study of material science has been long devoted to the disentanglement of bulk structures which mainly entails finding the inner structure of materials. That structure is accountable for a major portion of materials’ properties. Yet, as our knowledge of these “backbones” enlarged so did the interest for the materials’ boundaries properties which means the properties at the frontier with the surrounding environment that is called interface. The interface is thus to be understood as the sum of the material’s surface plus the surrounding environment be it in solid, liquid or gas phase. The study of phenomena at this interface requires both the use of experimental and theoretical techniques and, above all, a wise combination of them in order to shed light over the most intimate details at atomic, molecular and mesostructure levels. Here, we report several cases to be used as proof of concept of the results achieved when studying interface phenomena by combining a myriad of experimental and theoretical tools to overcome the usual limitation regardind ¿atomic detail, size and time scales and systems of complex composition. Real world examples of the combined experimental-theoretical work and new tools, software, is offered to the readers.

Summarization: Phytoliths from two different wheat species, Triticum monococcum and Triticum durum, known for their long-lasting significance to humans, were studied by a multi-analytical approach. Characterisation of phytoliths assisted in understanding their microstructure and behaviour after extraction from plants by the dry ashing and the wet ashing methods. The phytoliths extracted from different parts of the plant, namely the inflorescence and the stem-leaves, were characterised by optical microscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray fluorescence spectroscopy (ED-XRF), elemental CHNS analysis, thermogravimetric and differential thermogravimetric analysis (TGA-DTGA) and scanning electron microscopy coupled by energy-dispersive spectroscopy (SEM/EDS). The plants were cultivated at the same period and under the same climatic conditions in the Pella area, northern Greece. The mineralogical and chemical composition of the recovered phytoliths is controlled by the extraction method, strongly suggesting that comparison of phytoliths extracted from plants is meaningful only if the method of extraction remains the same. Physicochemical characteristics of fresh phytoliths extracted from plants provided useful information on the their preservation state after laboratory processing that may further contribute to the study of aged phytoliths in archaeological sites. Presented on: Archaeological and Anthropological Sciences

Species of Haliotis ~abalone! show high variety in structure and mineralogy of the shell. One of the European species ~Haliotis tuberculata! in particular has an unusual shell structure in which calcite and aragonite coexist at a microscale with small patches of aragonite embedded in larger calcitic zones. A detailed examination of the boundary between calcite and aragonite using analytical microscopies shows that the organic contents of calcite and aragonite differ. Moreover, changes in the chemical composition of the two minerals seem to be gradual and define a micrometric zone of transition between the two main layers. A similartransition zone has been observed between the layers in more classical and regularly structured mollusk shells. The imbrication of microscopic patches of aragonite within a calcitic zone suggests the occurrence of very fastphysiological changes in these taxa.