The mollusk shell mobilizes calcium from environment for skeletal mineralization.This occurs through synthesizing solidsin solution in the presence of organic molecules of specific interior regions of the conch shell....The mollusk shell mobilizes calcium from environment for skeletal mineralization.This occurs through synthesizing solidsin solution in the presence of organic molecules of specific interior regions of the conch shell.The ultrastructure and microhardnessof the Hemifusus tuba conch shell living in the Huang/Bo sea area are investigated in the paper.It is shown that thecomposition and microstructure of the mollusk shell vary in different positions.The prodissoconch shell consists only of aragonitewith the crossed-lamellar microstructure.While the spiral shell and the body shell of the Hemifusus tuba conch shell arecomposed of one calcite layer and several aragonite layers.The calcite layer consists of cylindrical grains,but the aragonitelayers are crossed-lamellar ultrastructure at three size scales.The minimum structure size (the third-order lamella) is at about20 nm - 80 nm.The margin of shell aperture is only composed of calcite with cylindrical grains.This natural optimization of theshell microstructure is intimately due to the growth of the Organic matrix.At different positions the microhardness of molluscshell is different due to different crystal structures and crystal arrangements.The growth process of shells allows a constantrenewal of the material,thus enabling their functional adaptation to external environments.展开更多
Haliotis discus hannai Ino （abalone shell） and Hemifusus tuba conch shell have been studied for the purpose to comparatively investigate the mechanisms by which nature designs composites. It is shown that both shell...Haliotis discus hannai Ino （abalone shell） and Hemifusus tuba conch shell have been studied for the purpose to comparatively investigate the mechanisms by which nature designs composites. It is shown that both shells are composed of aragonite and a small amount of proteins while the conch shell shows finer microstructure but lower strength than aba- lone shell. It is also shown that the fresh shells exhibits better property than those after heat-treatments. It is therefore sup- posed that the size of inorganic substance is not a dominant factor to improve strength, while both proteins in shells and the microstructure of inorganic matter also play important roles.展开更多
The microstructures of conch shell were observed with scanning electronic microscope （SEM）, and a kind of inclined-cross microstructure of aragonite sheets was found. The maximal pull-out force of the inclined-cros...The microstructures of conch shell were observed with scanning electronic microscope （SEM）, and a kind of inclined-cross microstructure of aragonite sheets was found. The maximal pull-out force of the inclined-cross microstructure was analyzed based on its representative model and compared with that of a conventional 0 °- structure. The experimental result indicates that the maximal pull-out force of the inclined-cross microstructure is markedly larger than that of the 0°- structure.展开更多
Given the socio-economic consequences associated with declaring areas of ocean protected in order to achieve conservation objectives, this paper contributes to the growing global need to assess Marine Protected Areas ...Given the socio-economic consequences associated with declaring areas of ocean protected in order to achieve conservation objectives, this paper contributes to the growing global need to assess Marine Protected Areas (MPAs) as an effective management tool. It adds to the current body of knowledge on MPA effectiveness by conducting an evaluation of the Tobago Cays Marine Park (TCMP), located in St. Vincent and the Grenadines (SVG) in the eastern Caribbean, using a modified MPA effectiveness framework. Due to the limited information existing about the current performance of this MPA, this assessment also provides needed insight on the effect that the TCMP is having on the marine ecosystem, as well as its overall management performance. By comparing the performance of the MPA over a 10-year span (2007 and 2016), the results indicate that overall, the TCMP could be described as having limited success when key management categories of context, planning, input, process, output and outcomes are evaluated. In particular, efforts dedicated to planning, process and outcomes are assessed as deficient. Furthermore, the analysis revealed that efforts to realize the stated goals relating to conservation, public awareness and public education were being neglected. However, considerable effort was being expended by TCMP staff on achieving the remaining goal focusing on deriving economic benefits from touristic activities in the Park. Preliminary field research examining the effects of the TCMP on the abundance and density of an economically important species, Lobatus gigas, (commonly referred to as the queen conch) showed the TCMP as having no effect towards conch protection. The results and recommendations of this study, combined with continued monitoring of a recommended targeted suite of indicators, could contribute to better-informed adaptive MPA management, leading to progress towards the achievement of the stated goals for the TCMP.展开更多
Seashells,commonly referred to as nature’s armors against predatory attacks,have been serving as the inspirations for designing strong and tough engineering materials.Previous studies on conch shells have been focuse...Seashells,commonly referred to as nature’s armors against predatory attacks,have been serving as the inspirations for designing strong and tough engineering materials.Previous studies on conch shells have been focused on the shell body parts.The conch spines which are evenly distributed at the tail of conch shell are generally accepted as the decoration,enabling conch shells as art pieces.Here we report a new finding that nature uses curved reinforcements,different from the straight ones in conch body parts,to construct conch spines which exhibit 30%increase in fracture strength compared to conch shell body parts.The curved lamellae not only endow conch spines with pyramid-shape but also add extra shielding to the shells.Under equilibrium state,the curved lamellar configuration withholds 3 times higher loading than the straight one.Our finding uncovered nature’s wisdom in constructing seashells and provides an additional design guideline for utilizing curved reinforcements to achieve multifunctionalities and superior mechanical prowess.展开更多
文摘The mollusk shell mobilizes calcium from environment for skeletal mineralization.This occurs through synthesizing solidsin solution in the presence of organic molecules of specific interior regions of the conch shell.The ultrastructure and microhardnessof the Hemifusus tuba conch shell living in the Huang/Bo sea area are investigated in the paper.It is shown that thecomposition and microstructure of the mollusk shell vary in different positions.The prodissoconch shell consists only of aragonitewith the crossed-lamellar microstructure.While the spiral shell and the body shell of the Hemifusus tuba conch shell arecomposed of one calcite layer and several aragonite layers.The calcite layer consists of cylindrical grains,but the aragonitelayers are crossed-lamellar ultrastructure at three size scales.The minimum structure size (the third-order lamella) is at about20 nm - 80 nm.The margin of shell aperture is only composed of calcite with cylindrical grains.This natural optimization of theshell microstructure is intimately due to the growth of the Organic matrix.At different positions the microhardness of molluscshell is different due to different crystal structures and crystal arrangements.The growth process of shells allows a constantrenewal of the material,thus enabling their functional adaptation to external environments.
文摘Haliotis discus hannai Ino （abalone shell） and Hemifusus tuba conch shell have been studied for the purpose to comparatively investigate the mechanisms by which nature designs composites. It is shown that both shells are composed of aragonite and a small amount of proteins while the conch shell shows finer microstructure but lower strength than aba- lone shell. It is also shown that the fresh shells exhibits better property than those after heat-treatments. It is therefore sup- posed that the size of inorganic substance is not a dominant factor to improve strength, while both proteins in shells and the microstructure of inorganic matter also play important roles.
文摘The microstructures of conch shell were observed with scanning electronic microscope （SEM）, and a kind of inclined-cross microstructure of aragonite sheets was found. The maximal pull-out force of the inclined-cross microstructure was analyzed based on its representative model and compared with that of a conventional 0 °- structure. The experimental result indicates that the maximal pull-out force of the inclined-cross microstructure is markedly larger than that of the 0°- structure.
文摘Given the socio-economic consequences associated with declaring areas of ocean protected in order to achieve conservation objectives, this paper contributes to the growing global need to assess Marine Protected Areas (MPAs) as an effective management tool. It adds to the current body of knowledge on MPA effectiveness by conducting an evaluation of the Tobago Cays Marine Park (TCMP), located in St. Vincent and the Grenadines (SVG) in the eastern Caribbean, using a modified MPA effectiveness framework. Due to the limited information existing about the current performance of this MPA, this assessment also provides needed insight on the effect that the TCMP is having on the marine ecosystem, as well as its overall management performance. By comparing the performance of the MPA over a 10-year span (2007 and 2016), the results indicate that overall, the TCMP could be described as having limited success when key management categories of context, planning, input, process, output and outcomes are evaluated. In particular, efforts dedicated to planning, process and outcomes are assessed as deficient. Furthermore, the analysis revealed that efforts to realize the stated goals relating to conservation, public awareness and public education were being neglected. However, considerable effort was being expended by TCMP staff on achieving the remaining goal focusing on deriving economic benefits from touristic activities in the Park. Preliminary field research examining the effects of the TCMP on the abundance and density of an economically important species, Lobatus gigas, (commonly referred to as the queen conch) showed the TCMP as having no effect towards conch protection. The results and recommendations of this study, combined with continued monitoring of a recommended targeted suite of indicators, could contribute to better-informed adaptive MPA management, leading to progress towards the achievement of the stated goals for the TCMP.
文摘Seashells,commonly referred to as nature’s armors against predatory attacks,have been serving as the inspirations for designing strong and tough engineering materials.Previous studies on conch shells have been focused on the shell body parts.The conch spines which are evenly distributed at the tail of conch shell are generally accepted as the decoration,enabling conch shells as art pieces.Here we report a new finding that nature uses curved reinforcements,different from the straight ones in conch body parts,to construct conch spines which exhibit 30%increase in fracture strength compared to conch shell body parts.The curved lamellae not only endow conch spines with pyramid-shape but also add extra shielding to the shells.Under equilibrium state,the curved lamellar configuration withholds 3 times higher loading than the straight one.Our finding uncovered nature’s wisdom in constructing seashells and provides an additional design guideline for utilizing curved reinforcements to achieve multifunctionalities and superior mechanical prowess.
