Search results for " shells"
showing 10 items of 60 documents
Our Friend and Mathematician Karl Strambach
2020
This paper is dedicated to Karl Strambach on the occasion of his 80th birthday. Here we want to describe our work with Prof. Karl Strambach.
Evolution and biomineralization of pteropod shells
2021
12 pages; International audience; Shelled pteropods, known as sea butterflies, are a group of small gastropods that spend their entire lives swimming and drifting in the open ocean. They build thin shells of aragonite, a metastable polymorph of calcium carbonate. Pteropod shells have been shown to experience dissolution and reduced thickness with a decrease in pH and therefore represent valuable bioindicators to monitor the impacts of ocean acidification. Over the past decades, several studies have highlighted the striking diversity of shell microstructures in pteropods, with exceptional mechanical properties, but their evolution and future in acidified waters remains uncertain. Here, we re…
Temperature-induced microstructural changes in shells of laboratory-grown Arctica islandica (Bivalvia).
2021
Bivalve shells are increasingly used as archives for high-resolution paleoclimate analyses. However, there is still an urgent need for quantitative temperature proxies that work without knowledge of the water chemistry–as is required for δ18O-based paleothermometry–and can better withstand diagenetic overprint. Recently, microstructural properties have been identified as a potential candidate fulfilling these requirements. So far, only few different microstructure categories (nacreous, prismatic and crossed-lamellar) of some short-lived species have been studied in detail, and in all such studies, the size and/or shape of individual biomineral units was found to increase with water temperat…
Climate variation during the Holocene influenced the skeletal properties of Chamelea gallina shells in the North Adriatic Sea (Italy)
2021
Understanding how marine taxa will respond to near-future climate changes is one of the main challenges for management of coastal ecosystem services. Ecological studies that investigate relationships between the environment and shell properties of commercially important marine species are commonly restricted to latitudinal gradients or small-scale laboratory experiments. This paper aimed to explore the variations in shell features and growth of the edible bivalve Chamelea gallina from the Holocene sedimentary succession to present-day thanatocoenosis of the Po Plain-Adriatic Sea system (Italy). Comparing the Holocene sub-fossil record to modern thanatocoenoses allowed obtaining an insight o…
The shell organic matrix of the crossed lamellar queen conch shell (Strombus gigas)
2014
10 pages; International audience; In molluscs, the shell organic matrix comprises a large set of biomineral-occluded proteins, glycoproteins and polysaccharides that are secreted by the calcifying mantle epithelium, and are supposed to display several functions related to the synthesis of the shell. In the present paper, we have characterized biochemically the shell matrix associated to the crossed-lamellar structure of the giant queen conch Strombus gigas. The acid-soluble (ASM) and acid-insoluble (AIM) matrices represent an extremely minor fraction of the shell. Both are constituted of polydisperse and of few discrete proteins among which three fractions, obtained by preparative SDS-PAGE …
The shell matrix of the european thorny oyster, Spondylus gaederopus: microstructural and molecular characterization.
2020
17 pages; International audience; Molluscs, the largest marine phylum, display extraordinary shell diversity and sophisticated biomineral architectures. However, mineral-associated biomolecules involved in biomineralization are still poorly characterised.We report the first comprehensive structural and biomolecular study of Spondylus gaederopus, a pectinoid bivalve with a peculiar shell texture. Used since prehistoric times, this is the best-known shell of Europe’s cultural heritage. We find that Spondylus microstructure is very poor in mineral-bound organics, which are mostly intercrystalline and concentrated at the interface between structural layers.Using high-resolution liquid chromatog…
Shell proteome of rhynchonelliform brachiopods.
2015
7 pages; International audience; Brachiopods are a phylum of marine invertebrates that have an external bivalved shell to protect their living tissues. With few exceptions, this biomineralized structure is composed of calcite, mixed together with a minor organic fraction, comprising secreted proteins that become occluded in the shell structure, once formed. This organic matrix is thought to display several functions, in particular, to control mineral deposition and to regulate crystallite shapes. Thus, identifying the primary structure of matrix proteins is a prerequisite for generating bioinspired materials with tailored properties. In this study, we employed a proteomic approach to identi…
Multi-isotopic and trace element evidence against different formation pathways for oyster microstructures
2021
Geochimica et cosmochimica acta 308, 326-352 (2021). doi:10.1016/j.gca.2021.06.012
New Alternative in the Methodology of Extraction and Dyeing with Active Molecules Derived from Vegetal Sources
2016
Abstract The general objective of this study refers to the identification of a sustainable and physical methodology of extraction of active compounds, envisaging the preservation of the high purity active natural dye molecule from nut shell (juglone), even under the conditions of an extraction performed in a mixt solvent medium (water-ethanol). The second major objective of the study consists of the application of these above mentioned dyes onto natural and synthetic substrates, thus making a correlation between their colour attributes and the fibrous composition of the substrates they are applied on. The motivation of this research was given by the identification of an improved extraction …
Discontinuous Galerkin models for composite multilayered shells with higher order kinematics
2021
Composite multilayered shells are widely employed in aerospace, automotive and civil engineering as weight-saving structural components. In multilayered shells, despite its versatility, the interplay between the curved geometry and the properties of the composite layers induces a complex distribution of the mechanical fields, which must be accurately resolved to safely employ generally curved composite shells as load-bearing structures. The problem can be addressed through the two-dimensional shell theories, which are based on suitable assumptions on the behavior of the mechanical fields throughout the thickness of the considered structures and are a viable strategy for reducing the computa…