scholarly journals How to build a puncture- and breakage-resistant eggshell? Mechanical and structural analyses of avian brood parasites and their hosts

2021 ◽  
Author(s):  
Analía V. López ◽  
Raúl E. Bolmaro ◽  
Martina Ávalos ◽  
Lía N. Gerschenson ◽  
Juan C. Reboreda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reproductive Strategies ◽  
Structural Organization ◽  
Structural Features ◽  
Comparative Approach ◽  
Eggshell Thickness ◽  
Brood Parasites ◽  
Egg Destruction ◽  
Xrd Techniques ◽  
Destructive Behaviors

Evolved eggshell strength is greater in several lineages of obligate avian brood parasites (birds that lay their eggs in other species’ nests) compared to their hosts. Greater strength is typically indirectly implied by eggshell thickness comparisons between parasites and hosts. Nevertheless, there is strong evidence that the eggshell structural organization differentially influences its mechanical properties. Using instrumental puncture tests and SEM/EBSD and XRD techniques, we studied the most relevant eggshell mechanical, textural, ultra- and microstructural features between several host species and their parasitic cowbirds (Molothrus spp.) that display different egg destructive behaviors reducing host reproductive fitness, and include the more frequently host-egg puncturer M. rufoaxillaris and M. bonariensis, and the host-egg remover M. ater. The results, analyzed using a phylogenetic comparative approach, showed interspecific patterns in the mechanical and structural features. Overall, eggshell of both species of the two egg-puncturer parasites (but not of M. ater) were stronger, stiffer, and required greater stress to produce its fracture than the respective hosts’ eggs. These features were affected by eggshell micro- and ultrastructures, related to the increased of the intercrystalline boundary network acting in cooperation with the increased of the palisade layers' thickness. Both of these structural traits generate more options and greater lengths of intercrystalline paths, increasing the energy consumed in crack or fissure propagation. The reported patterns of all these diverse eggshell features support a new set of interpretations, confirming several hypotheses regarding the impacts of both reproductive strategies (parasitic vs. parental) and parasitic egg destruction behaviors (more vs. less frequently puncturing).

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Structural features and strength behavior of TRIP/TWIP steels

2020 ◽  
pp. 5-18
Author(s):  
D. V. Prosvirnin ◽  
◽  
M. S. Larionov ◽  
S. V. Pivovarchik ◽  
A. G. Kolmakov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Thermomechanical Processing ◽  
Maximum Load ◽  
Structural Features ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Structural And Functional Properties ◽  
Twip Steels ◽  
The Creation

A review of the literature data on the structural features of TRIP / TWIP steels, their relationship with mechanical properties and the relationship of strength parameters under static and cyclic loading was carried out. It is shown that the level of mechanical properties of such steels is determined by the chemical composition and processing technology (thermal and thermomechanical processing, hot and cold pressure treatment), aimed at achieving a favorable phase composition. At the atomic level, the most important factor is stacking fault energy, the level of which will be decisive in the formation of austenite twins and / or the formation of strain martensite. By selecting the chemical composition, it is possible to set the stacking fault energy corresponding to the necessary mechanical characteristics. In the case of cyclic loads, an important role is played by the strain rate and the maximum load during testing. So at high loading rates and a load approaching the yield strength under tension, the intensity of the twinning processes and the formation of martensite increases. It is shown that one of the relevant ways to further increase of the structural and functional properties of TRIP and TWIP steels is the creation of composite materials on their basis. At present, surface modification and coating, especially by ion-vacuum methods, can be considered the most promising direction for the creation of such composites.

scholarly journals A Comparative Perspective on Functionally-Related, Intracellular Calcium Channels: The Insect Ryanodine and Inositol 1,4,5-trisphosphate Receptors

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1031
Author(s):  
Umut Toprak ◽  
Cansu Doğan ◽  
Dwayne Hegedus
Keyword(s):  
Pest Control ◽  
Structural Organization ◽  
Insect Cells ◽  
Expression Patterns ◽  
Regulatory Mechanisms ◽  
Comparative Approach ◽  
Insect Development ◽  
Current Review ◽  
Inositol 1,4,5 Trisphosphate ◽  
Target Sites

Calcium (Ca2+) homeostasis is vital for insect development and metabolism, and the endoplasmic reticulum (ER) is a major intracellular reservoir for Ca2+. The inositol 1,4,5- triphosphate receptor (IP3R) and ryanodine receptor (RyR) are large homotetrameric channels associated with the ER and serve as two major actors in ER-derived Ca2+ supply. Most of the knowledge on these receptors derives from mammalian systems that possess three genes for each receptor. These studies have inspired work on synonymous receptors in insects, which encode a single IP3R and RyR. In the current review, we focus on a fundamental, common question: “why do insect cells possess two Ca2+ channel receptors in the ER?”. Through a comparative approach, this review covers the discovery of RyRs and IP3Rs, examines their structures/functions, the pathways that they interact with, and their potential as target sites in pest control. Although insects RyRs and IP3Rs share structural similarities, they are phylogenetically distinct, have their own structural organization, regulatory mechanisms, and expression patterns, which explains their functional distinction. Nevertheless, both have great potential as target sites in pest control, with RyRs currently being targeted by commercial insecticide, the diamides.

Correlation between structural features and mechanical properties of boron nitride fibres derived from alkylaminoborazines

2005 ◽  
Vol 25 (2-3) ◽  
pp. 157-162 ◽  
Author(s):  
Philippe Miele ◽  
Bérangère Toury ◽  
Fernand Chassagneux ◽  
René Fulchiron
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Structural Features

Synthesis and Characterization of a Porous Silicon Filter with Si3N4 Whiskers

2009 ◽  
Vol 289-292 ◽  
pp. 185-194 ◽  
Author(s):  
Milagros Wong-Sifuentes ◽  
Makoto Nanko ◽  
Joaquín Lira-Olivares
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Fine Particles ◽  
Process Analysis ◽  
Young Modulus ◽  
Process Conditions ◽  
Phase Reaction ◽  
Nitridation Process ◽  
Xrd Techniques

Removal of fine particles from some gas-product effluents from motors and industries, using filters, is an important subject in the field of public health and environment. In the present work, a porous silicon filter was produced, which is able to capture most of the particles undesirable for the environment (transported by gases), larger than the pore diameter (micrometer) of the filter and even smaller size particles. The development of whiskers inside of the pores of the silicon filter, improve its ability to catch smaller particles than the filter’s size pores. Those whiskers are made of Silicon Nitride, produced by a Nitridation process. A different time-temperature schedule for the formation of -silicon nitride (-Si3N4) whiskers by direct Nitridation of the porous silicon filter was studied, in order to optimize the amount of whiskers and improve the filter quality. Four different temperatures (1000, 1100, 1200 and 1300 °C) were selected, each with two different holding times (15 min and 1 hour) for complete Nitridation with N2 and N2+H2 gases. The as-formed whiskers were characterized by SEM, XRD techniques and the process conditions were studied. The filter with the Si3N4 whiskers was characterized evaluating mechanical properties of the porous silicon filter (Micro Hardness and Young Modulus). The permeability measurements were made before and after the Nitridation process. Analysis indicates that the higher Si3N4 whiskers formation temperature was 1300 °C for the gas (N2+H2) phase reaction results from the lower PSiO2/Psio ratio in the Si-N system. Titanium (99% pure) was used with the purpose of reduction of the oxygen partial pressure and the increase of the amount of -silicon nitride whiskers. The porous silicon filter improved its conditions with the silicon nitride whiskers, even though decreases also the fluid permeability measurement. However, it has a smaller flow decrement than filters with smaller porosity. The mechanical properties did not have variation at all, the porosity size increased because of the diffusion of Si to form whiskers in the Nitridation process.

Computational Design and Optimization of Nerve Guidance Conduits for Improved Mechanical Properties and Permeability

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Shuo Zhang ◽  
Sanjairaj Vijayavenkataraman ◽  
Geng Liang Chong ◽  
Jerry Ying Hsi Fuh ◽  
Wen Feng Lu
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Mechanical Strength ◽  
Tensile Modulus ◽  
Computational Design ◽  
Structural Features ◽  
Nerve Tissue ◽  
High Porosity ◽  
Engineering Research ◽  
Design And Optimization

Nerve guidance conduits (NGCs) are tubular tissue engineering scaffolds used for nerve regeneration. The poor mechanical properties and porosity have always compromised their performances for guiding and supporting axonal growth. Therefore, in order to improve the properties of NGCs, the computational design approach was adopted to investigate the effects of different NGC structural features on their various properties, and finally, design an ideal NGC with mechanical properties matching human nerves and high porosity and permeability. Three common NGC designs, namely hollow luminal, multichannel, and microgrooved, were chosen in this study. Simulations were conducted to study the mechanical properties and permeability. The results show that pore size is the most influential structural feature for NGC tensile modulus. Multichannel NGCs have higher mechanical strength but lower permeability compared to other designs. Square pores lead to higher permeability but lower mechanical strength than circular pores. The study finally selected an optimized hollow luminal NGC with a porosity of 71% and a tensile modulus of 8 MPa to achieve multiple design requirements. The use of computational design and optimization was shown to be promising in future NGC design and nerve tissue engineering research.

QSPR STUDY OF RHEOLOGICAL AND MECHANICAL PROPERTIES OF CHLOROPRENE RUBBER ACCELERATORS

2014 ◽  
Vol 87 (2) ◽  
pp. 219-238 ◽  
Author(s):  
Roberto Todeschini ◽  
Viviana Consonni ◽  
Davide Ballabio ◽  
Andrea Mauri ◽  
Matteo Cassotti ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mathematical Models ◽  
Structural Features ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Quantitative Structure Property Relationships ◽  
Cure Time ◽  
Chloroprene Rubber ◽  
Experimental Values ◽  
Rubber Accelerators

ABSTRACT In this preliminary study, mathematical models based on Quantitative Structure Property Relationships (QSPR) were applied in order to analyze how molecular structure of chloroprene rubber accelerators relates to their rheological and mechanical properties. QSPR models were developed in order to disclose which structural features mainly affect the mechanism of vulcanization. In such a way QSPR can help in a faster and more parsimonious design of new chloroprene rubber curative molecules. Regression mathematical models were calibrated on two rheological properties (scorch time and optimum cure time) and three mechanical properties (modulus 100%, hardness, and elongation at break). Models were calculated using experimental values of 14 accelerators belonging to diverse chemical classes and validated by means of different strategies. All the derived models gave a good degree of fitting (R2 values ranging from 84.5 to 98.7) and a satisfactory predictive power. Moreover, some hypotheses on the correlations between specific structural features and the analyzed rheological and mechanical properties were drawn. Owing to the relatively small set of accelerators used to calibrate the models, these hypotheses should be further investigated and proved.

scholarly journals Energy localization and frequency analysis in the locust ear

2014 ◽  
Vol 11 (90) ◽  
pp. 20130857 ◽  
Author(s):  
Robert Malkin ◽  
Thomas R. McDonagh ◽  
Natasha Mhatre ◽  
Thomas S. Scott ◽  
Daniel Robert
Keyword(s):  
Mechanical Properties ◽  
Signal Analysis ◽  
Structural Features ◽  
Dependent Manner ◽  
Sound Waves ◽  
Energy Localization ◽  
Frequency Signal ◽  
Element Analysis ◽  
Frequency Dependent ◽  
Necessary And Sufficient

Animal ears are exquisitely adapted to capture sound energy and perform signal analysis. Studying the ear of the locust, we show how frequency signal analysis can be performed solely by using the structural features of the tympanum. Incident sound waves generate mechanical vibrational waves that travel across the tympanum. These waves shoal in a tsunami-like fashion, resulting in energy localization that focuses vibrations onto the mechanosensory neurons in a frequency-dependent manner. Using finite element analysis, we demonstrate that two mechanical properties of the locust tympanum, distributed thickness and tension, are necessary and sufficient to generate frequency-dependent energy localization.

Sign in / Sign up

Export Citation Format

Share Document