Mechanical Organization of Cantileverlike Sessile Organisms: Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 127-142
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Elastic Modulus ◽  
Body Wall ◽  
Local Buckling ◽  
Beam Theory ◽  
Extension Rate ◽  
Flexural Stiffness ◽  
Sea Anemones ◽  
Order Of Magnitude ◽  
Anthopleura Xanthogrammica ◽  
Sessile Organisms

Engineering beam theory has been used to analyse the ways in which body shape and elastic modulus of two species of sea anemones affect their mechanical responses to flow. 1.Anthopleura xanthogrammica is exposed to wave action, but because it is short, wide, and thick-walled, maximum tensile stresses in its body walls due to flow forces are an order of magnitude lower than those in the tall, slim, thin-walled, calm-water sea anemone Metridium senile.2. The elastic modulus of M. senile body wall is more dependent on extension rate than is that of A. xanthogrammica. Because the extension rate of M. senile body wall in tidal currents is higher than that of A. xanthogrammica in wave surge, the moduli of walls from these species when exposed to such flow conditions are similar, between 0.1 and 0.3 MN.m−2.3. The flexural stiffness of M. senile is lowest in the upper column where the anemones bend in currents: this orients their filter-feeding oral discs normal to the currents. The flexural stiffness of A. xanthogrammica is one to two orders of magnitude higher than that of M. senile; A. xanthogrammica remain upright in wave surge and feed on mussels that fall on their oral discs.4. The deflexions of these anemones predicted using beam theory are consistent with those observed in nature.5. The critical stress to produce local buckling is an order of magnitude lower for M. senile than for A. xanthogrammica.6. Several general principles of the organization of cantilever-like sessile organisms are revealed by this study of sea anemones.

Mechanical Diversity of Connective Tissue of the Body Wall of Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 107-125
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Connective Tissue ◽  
Body Wall ◽  
Polarized Light ◽  
Structural Features ◽  
Mechanical Tests ◽  
The Body ◽  
Sea Anemones ◽  
Collagen Fibres ◽  
Postural Changes ◽  
Anthopleura Xanthogrammica

Techniques for analysing polymer mechanics were used to describe quantitatively the time-dependent mechanical properties of the body-wall connective tissue (mesogloea) and to indicate macromolecular mechanisms responsible for the mechanical behaviour of two species of sea anemones, Metridium senile and Anthopleura xanthogrammica. 1. The mesogloea of M. senile is more extensible and less resilient than that of A. xanthogrammica when stressed for periods comparable to the duration of flow forces the anemones encounter and the postural changes they perform.2. Polarized light microscopy and SEM reveal that the reinforcing collagen fibres in the mesogloea are aligned parallel with the major stress axes in the body wall.3. Mechanical tests and observations of composition and microstructure indicate that the mesogloea of A. xanthogrammica is less extensible than that of M. senile because molecular entanglements (due to more closely packed parallel collagen fibres and to a higher concentration of polymers in the interfibrillar matrix) retard the extension of A. xanthogrammica mesogloea. This study illustrates how structural features on the macromolecular and microscopic levels of organization of an organism can equip that organism for the particular mechanical activities it performs and the environmental forces it encounters.

Effects of Sea Anemones on the Flow Forces They Encounter

1977 ◽  
Vol 69 (1) ◽  
pp. 87-105 ◽  
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Drag Force ◽  
Mechanical Forces ◽  
Flowing Water ◽  
Sea Anemones ◽  
Water Currents ◽  
Mechanical Responses ◽  
Drag Forces ◽  
Metridium Senile ◽  
Anthopleura Xanthogrammica ◽  
Sessile Organisms

Two species of sea anemones, Metridium senile and Anthopleura xanthogrammica, illustrate the sorts of compromises made by sessile organisms between maximizing the transport done and minimizing the mechanical forces caused by flow. 1.M. senile occur in calm areas, but because they are tall, they are exposed to mainstream current velocities. Although A. xanthogrammica occur in areas exposed to wave action, they are short and effectively hidden from mainstream velocities.2. Measurements of drag forces on anemones and models in a flow tank and in the field indicate that the shapes, sizes, flexibilities, and behaviours of anemones affect the flow forces they encounter.3. Although M. senile and A. xanthogrammica occur in different flow habitats, the drag force on an individual of either species is about 1 N.4. The water currents encountered by these anemones and their mechanical responses to the currents can be related to the manner in which the anemones harvest food from flowing water.

scholarly journals Measurements of sea-ice flexural stiffness by pressure characteristics of flexural-gravity waves

2013 ◽  
Vol 54 (64) ◽  
pp. 51-60 ◽  
Author(s):  
Aleksey Marchenko ◽  
Eugene Morozov ◽  
Sergey Muzylev
Keyword(s):  
Elastic Modulus ◽  
Gravity Waves ◽  
Water Depth ◽  
Water Pressure ◽  
Field Measurements ◽  
Effective Elastic Modulus ◽  
Flexural Stiffness ◽  
Flexural Gravity Waves ◽  
Using Data ◽  
Relative Errors

Abstract A method to estimate the flexural stiffness and effective elastic modulus of floating ice is described and analysed. The method is based on the analysis of water pressure records at two or three locations below the bottom of floating ice when flexural-gravity waves propagate through the ice. The relative errors in the calculations of the ice flexural stiffness and the water depth are analysed. The method is tested using data from field measurements in Tempelfjorden, Svalbard, where flexural-gravity waves were excited by an icefall at the front of the outflow glacier Tunabreen in February 2011.

Viso-Elastic Properties of the Body-Wall of Sea Anemones

1962 ◽  
Vol 39 (3) ◽  
pp. 373-386
Author(s):  
R. MCN. ALEXANDER
Keyword(s):  
Tensile Stress ◽  
Elastic Properties ◽  
Body Wall ◽  
The Body ◽  
Polymeric System ◽  
Retardation Time ◽  
Sea Anemones

1. Creep of narcotized Metridium and Calliactis body-wall at constant tensile stress has been studied quantitatively. 2. It was found to be reversible, and seemed to be controlled by the mesogloea. Its course could be represented by equations of the formε(t)= εo+ευ(I-e-t/τ),where the retardation time τ was about 1 hr. for Metridium and many hours for Calliactis. 3. The results can most simply be explained in terms of a cross-linked and a noncross-linked polymeric system, acting in parallel. An explanation in terms of a lattice of inextensible fibres is not satisfactory. 4. The results are discussed in relation to the behaviour of the animals.

A finite element model to study the effect of porosity location on the elastic modulus of a cantilever beam

2019 ◽  
Vol 43 (4) ◽  
pp. 443-453
Author(s):  
Stephen M. Handrigan ◽  
Sam Nakhla
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Focused Ion Beam ◽  
Mechanical Response ◽  
Ion Beam ◽  
Three Dimensional ◽  
Beam Theory ◽  
Element Model ◽  
Fe Model ◽  
Three Dimensional Finite Element

An investigation to determine the effect of porosity concentration and location on elastic modulus is performed. Due to advancements in testing methods, the manufacturing and testing of microbeams to obtain mechanical response is possible through the use of focused ion beam technology. Meanwhile, rigorous analysis is required to enable accurate extraction of the elastic modulus from test data. First, a one-dimensional investigation with beam theory, Euler–Bernoulli and Timoshenko, was performed to estimate the modulus based on load-deflection curve. Second, a three-dimensional finite element (FE) model in Abaqus was developed to identify the effect of porosity concentration. Furthermore, the current work provided an accurate procedure to enable accurate extraction of the elastic modulus from load-deflection data. The use of macromodels such as beam theory and three-dimensional FE model enabled enhanced understanding of the effect of porosity on modulus.

Activities of enzymes in β-carboxylation reactions and of catalase in cell-free preparations from the symbiotic dinoflagellates Symbiodinium spp. from a coral, a clam, a zoanthid and two sea anemones

1986 ◽  
Vol 228 (1253) ◽  
pp. 483-492 ◽  
Keyword(s):  
Malate Dehydrogenase ◽  
Sea Anemones ◽  
Stony Coral ◽  
Enzyme Systems ◽  
Glycollate Dehydrogenase ◽  
Order Of Magnitude ◽  
Symbiotic Dinoflagellates ◽  
Tridacna Maxima ◽  
First Time ◽  
Different Levels

Cell-free extracts of cultured and freshly isolated symbiotic dinoflagellates, Symbiodinium spp, isolated from the stony coral Montipora verrucosa , the clam Tridacna maxima , the zoanthid Palythoa sp. and the sea anemone Aiptasia pulchella were assayed for the enzyme systems involved in β-carboxylation and photorespiration. Markedly different levels of phosphoenolpyruvate carboxylase (EC 4 . 1 . 1 .31; PEP-case) activity were demonstrated in extracts from the different algae. The activity of PEP-case in the algae from M. verrucosa was highest, being an order of magnitude higher than PEP-case in algae from Palythoa sp. and up to 25-fold higher than that in algae from A. pulchella and T. maxima . The algae from M. verrucosa also exhibited pyruvate-P i dikinase (EC 2 . 7 .9 .1) activity. When these data are combined with previous demonstrations of the existence of NAD malate dehydrogenase and NADP malate dehydrogenase (decarboxylating; ‘malic enzyme’) in these algae, the indications are that they possess functional β-carboxylation enzyme systems. Past demonstrations of the photoassimilation of 14 CO 2 into glycollate by Symbiodinium spp. indicated photorespiration. The demonstration for the first time of activity of catalase (EC 1 . 11 . 1 . 6) when viewed in light of previous demonstrations of other composite enzymes of the photorespiratory pathway (e.g. phosphoglycollate phosphatase, glycollate dehydrogenase), add further confirmation to the disputed existence of a functional photorespiratory system in these symbiotic dinoflagellates.

MATERIAL PROPERTIES OF ADULT RAT SKULL

2011 ◽  
Vol 11 (05) ◽  
pp. 1199-1212 ◽  
Author(s):  
HAOJIE MAO ◽  
CHRISTINA WAGNER ◽  
FENGJIAO GUAN ◽  
YENER N. YENI ◽  
KING H. YANG
Keyword(s):  
Elastic Modulus ◽  
Energy Density ◽  
Cross Sections ◽  
Material Properties ◽  
Soft Tissues ◽  
Beam Theory ◽  
Bending Stress ◽  
Adult Rats ◽  
Adult Rat ◽  
Young’S Moduli

Development of advanced computational rat head models requires accurate material properties of the rat brain, meninges, skull, and other soft tissues. This study investigated adult rat skull material properties, which are very limited in the current literature. A total of 20 skull specimens were harvested from 10 adult rats. High resolution (16 μm) microcomputed tomography scans were performed for each specimen to observe dimensional changes within each specimen and internal porosities through the cross sections. The specimens were tested in three-point bending at loading velocities of 0.02 and 200 mm/s. The elastic modulus, energy absorbed to failure, energy density, and bending stress were calculated using classical beam theory. Results demonstrated that bending velocity (strain rate) had significant effect on elastic modulus and bending stress, but not on energy and energy density. The Young's moduli of rat skull measured in this study were comparable to those measured from the adult human skull.

A Methodology for Optimal Design of Composite Laminates Using Polar Formalism

2016 ◽  
Vol 32 (3) ◽  
pp. 255-266
Author(s):  
M. Kazemi ◽  
G. Verchery
Keyword(s):  
Elastic Modulus ◽  
Composite Laminates ◽  
Elastic Moduli ◽  
Optimization Technique ◽  
Laminated Plates ◽  
Flexural Stiffness ◽  
Numerical Examples ◽  
Composite Laminated Plates ◽  
Plane Anisotropy ◽  
Laminated Structures

AbstractAn innovative optimization technique is presented for the design of composite laminated plates subjected to in-plane loads. A list of quasi-homogeneous laminates that can be used as angle-ply materials is proposed as a comprehensive solution for optimum lay-up. Two optimization procedures are performed: Dimensioning of the flexural stiffness and the elastic modulus, which provides the optimal orientations for the layers and offer highest in-plane resistance to composite laminated structures. The polar formalism for plane anisotropy is used to represent the flexural stiffness and elastic modulus tensors. Numerical examples are resolved for two materials with different elastic moduli.

Study of Frequency Response of Quartz Crystal Microbalance to Different Wetting States of Micropillar Surfaces

2017 ◽  
Author(s):  
Junwei Su ◽  
Hamed Esmaeilzadeh ◽  
Hongwei Sun
Keyword(s):  
Quartz Crystal Microbalance ◽  
Nanoimprint Lithography ◽  
Quartz Crystal ◽  
Beam Theory ◽  
Frequency Shifts ◽  
Highly Nonlinear ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Potential Applications ◽  
Order Of Magnitude

Enhanced wettability, known as superhydrophobicity or superhydrophilicity has drawn extensive attention in the past for wide range potential applications such as superhydrophobic surfaces for self-cleaning, anti-icing, dropwise condensation, and drag reduction. This research focuses on the investigation of the frequency responses of quartz crystal microbalance (QCM) devices coated with micropillars to the different wetting states of drops. A theoretical model was developed to correlate the resonant frequency shifts of QCMs with the penetrated (Wenzel state) and suspended (Cassie state) states based on the Euler-Bernoulli beam theory. In the experimental validation of the theory, Poly(methyl methacrylate) (PMMA) micropillars were fabricated on the QCMs using nanoimprint lithography (NIL) method and the different wetting states were generated by plasma treatment and chemical coating. The frequency shifts of the QCM device were measured by a network analyzer. A good agreement between experimental measurements and theoretical predictions was obtained. It was found that the micropillars operating in the penetrated state results in one order of magnitude higher frequency shift of QCM than the micropillars in suspended state. There exists a highly nonlinear vibrating behavior of micropillars with different heights in both penetrated and suspended states. The QCM based technology is a valuable tool for studying the wettability of different superhydrophobic or superhydrophilic surfaces.

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