Search results for " shells"
showing 10 items of 60 documents
Le conchiglie di Lamarck come beni culturali
2012
Con questo contributo si è voluto ricordare che nella turbolenta Francia nel 1793 per la prima volta i beni naturali vengono ufficialmente riconosciuti anche come beni culturali facenti parte del patrimonio di un popolo, che li deve custodire e tutelare. Il tutto era scaturito dalla necessità di salvare dalla distruzione due acquasantiere costituite da 2 valve di tridacna, una conchiglia esotica, presenti nella Chiesa di S. Sulpice a Parigi. A questo importante evento partecipò attivamente anche Jean Baptiste Lamarck, Professore di Zoologia degli Insetti e dei Vermi presso il Museo Nazionale di Storia Naturale di Parigi. Proprio dallo studio delle conchiglie attuali, comparate con quelle fo…
The degradation of intracrystalline mollusc shell proteins: a proteomics study of Spondylus gaederopus.
2021
Mollusc shells represent excellent systems for the preservation and retrieval of genuine biomolecules from archaeological or palaeontological samples. As a consequence, the post-mortem breakdown of intracrystalline mollusc shell proteins has been extensively investigated, particularly with regard to its potential use as a "molecular clock" for geochronological applications. But despite seventy years of ancient protein research, the fundamental aspects of diagenesis-induced changes to protein structures and sequences remain elusive. In this study we investigate the degradation of intracrystalline proteins by performing artificial degradation experiments on the shell of the thorny oyster, Spo…
The youngest Trigoniida (Mollusca, Bivalvia) of Europe, including new genera and species from the type area of the Maastrichtian Stage
2022
Until recently, only a single species of trigoniid bivalve was known from the upper Maastrichtian Maastricht Formation in the type area of the Maastrichtian Stage (south-east Netherlands and adjacent Belgian and German territories); it was named Trigonia maestrichtiana by Alphonse Briart in 1888. This common, rather small species is here transferred to the genus Oistotrigonia, and a lectotype is designated. In addition, two new genera of very small rutitrigoniids, Wolfgangella and Anniedhondtella, and three new species, W. neilpearti, W. ignota and A. rieui, are erected. Most of the material available is preserved as (paired) external and internal moulds in a nearshore facies of indurated b…
Surface Chemistry Controls Magnetism in Cobalt Nanoclusters
2016
Magnetic properties of Co13 and Co55 nanoclusters, passivated by surface ligand shells that exhibit varying electronic interactions with the metal, are studied using density functional theory. The calculations show that the chemical nature of the bond between the ligand and the metal core (X-type or L-type) impacts the total magnetic moment of Co nanoclusters dramatically. Furthermore, the chemical identity of the ligand within each binding motif then provides a fine handle on the exhibited magnetic moment of the cluster. Thus, ligand shell chemistry is predicted to not only stabilize Co nanoclusters, but provide a powerful approach to control their magnetic properties, which combined enabl…
Nanoscale assembly processes revealed in the nacroprismatic transition zone of Pinna nobilis mollusc shells
2015
Intricate biomineralization processes in molluscs engineer hierarchical structures with meso-, nano-, and atomic architectures that give the final composite material exceptional mechanical strength and optical iridescence on the macroscale. This multiscale biological assembly inspires new synthetic routes to complex materials. Our investigation of the prism-nacre interface reveals nanoscale details governing the onset of nacre formation using high-resolution scanning transmission electron microscopy. A wedge polishing technique provides unprecedented, large-area specimens required to span the entire interface. Within this region, we find a transition from nanofibrillar aggregation to irregu…
A critical approach to the toxic metal ion removal by hazelnut and almond shells
2018
The adsorption capacity of ground hazelnut (HS) and almond (AS) shells towards Pb(II) and Cd(II) has been studied at pH = 5, in NaNO3 and NaCl ionic media, in the ionic strength range 0.05-0.5 mol L-1. Kinetic and equilibrium experiments were carried out by using the Differential Pulse Anodic Stripping Voltammetry technique to check the amount of the metal ion removed by HS and AS materials. Different kinetic and equilibrium equations were used to fit experimental data and a statistical study was done to establish the suitable model for the data fitting. A speciation study of the metal ions in solution was also done in order to evaluate the influence of the ionic medium on the adsorption pr…
A discontinuous Galerkin formulation for nonlinear analysis of multilayered shells refined theories
2023
A novel pure penalty discontinuous Galerkin method is proposed for the geometrically nonlinear analysis of multilayered composite plates and shells, modelled via high-order refined theories. The approach allows to build different two-dimensional equivalent single layer structural models, which are obtained by expressing the covariant components of the displacement field through-the-thickness via Taylor’s polynomial expansion of different order. The problem governing equations are deduced starting from the geometrically nonlinear principle of virtual displacements in a total Lagrangian formulation. They are addressed with a pure penalty discontinuous Galerkin method using Legendre polynomial…
Contrasting shell growth strategies in two Mediterranean bivalves revealed by oxygen-isotope ratio geochemistry: The case of Pecten jacobaeus and Gly…
2019
International audience; High-resolution stable-isotope ratio data (delta O-18, delta O-18) were used to study growth strategies of two bivalve species, Pecten jacobaeus (calcitic shell) and Glycymeris pilosa (aragonitic shell) from the North Adriatic Sea. The principal objectives of this study were to identify the period of the year when the growth line is formed in the shell of two target species, to identify the main growing season of these two species, to identify the environmental drivers of shell growth, and to evaluate the potential applicability of delta O-18 and delta O-18 values for the reconstruction of environmental variability. Samples were collected from the North Adriatic Sea …
Trace and minor element records in aragonitic bivalve shells as environmental proxies
2019
Abstract Investigation of the geochemical composition of bivalve shells can provide information on changes in the marine environment occurring during the lifespan of an organism. Three species, locally abundant in the Adriatic Sea, were chosen in this study, namely Glycymeris pilosa, Callista chione, and Venus verrucosa. Of these, G. pilosa has the longest lifespan, exceeding 50 years, and therefore presents a potential archive of decadal climate variability. The other two species, C. chione and V. verrucosa, are commercially important. Samples were collected alive by SCUBA diving in the North Adriatic Sea, near Barbariga, Istria. Major growth increments in these shells form on an annual ba…
Bivalve mollusks shells valorisation and recycling: market potentiality and novel building products
2023
Construction is a fundamental driver of the world economy, recognized as a sector that generates a great contribution to the social and economic development. At the same time, it shows an enormous environmental impact through an unstoppable consumption of non-renewable resources, a high energy consumption, and an associated atmospheric emission of pollutant. Consequently, the research and development of novel and green production processes and sustainable building materials is of paramount importance. The sustainability of materials and production processes could be improved by enhancing and reusing wastes from various industrial sectors. In this paper, the fishery sector will be analysed, …