scholarly journals The edge regions in tergites of the desert isopod Hemilepistus reaumuri: the transition from hard cuticle to flexible arthrodial membrane

2020 ◽  
Vol 126 (10) ◽  
Author(s):  
Franziska Ernst ◽  
Helge-Otto Fabritius ◽  
Erika Griesshaber ◽  
Wolfgang W. Schmahl ◽  
Andreas Ziegler
Keyword(s):  
Mechanical Properties ◽  
Anterior Part ◽  
Section Plane ◽  
Edge Region ◽  
Posterior Edge ◽  
Sagittal Section ◽  
Desert Habitat ◽  
Oriented Parallel ◽  
Local Stiffness ◽  
Hemilepistus Reaumuri

Abstract The arthrodial membrane is a thin and flexible type of cuticle that inserts at the edge regions of neighbouring rigid skeletal elements creating a flexible connection. In the present study, we analyzed the structure, mineral composition, calcite organization and local stiffness and hardness of edge regions that form transitions to the arthrodial membranes in the tergites of the desert isopod Hemilepistus reaumuri. For the transitions to the arthrodial membrane, the results show an increase in the thickness of the epicuticle at cost of the distal exocuticle and a calcite layer, an increase in the ratio of phosphorus to calcium and a decrease in the local mechanical properties. The posterior edge region contains an unusually large stack of unidirectionally oriented parallel fibrils projecting to the lateral sides. At the edge, it turns down into a long ventral cuticle overlapping an anterior part of the neighbouring tergite. It forms a thin arched gap between the tergites that can help reducing water loss through the arthrodial membrane and protects the arthrodial membrane upon predation. A thick ventral ridge near the transition to the arthrodial membrane carrying bristles can prevent sand grains from access to the arthrodial membrane. From the dorsal cuticle to the transition to the arthrodial membrane, calcite units become larger and single crystalline turning their c-axes orientation perpendicular to the sagittal section plane. Comparison with edge regions of the beach isopod Tylos europaeus reveal common characteristics of the edge region, but also specific adaptations to the desert habitat of H. reaumuri.

scholarly journals Mechanical properties and fibre density of steel fibrereinforced self-compacting concrete slabs by DIA and XCT approaches

2017 ◽  
Vol 23 (5) ◽  
pp. 604-612 ◽  
Author(s):  
Tomasz PONIKIEWSKI ◽  
Jacek KATZER
Keyword(s):  
Mechanical Properties ◽  
Fibre Length ◽  
Research Programme ◽  
Experimental Tests ◽  
Flexural Behaviour ◽  
Mixture Flow ◽  
Steel Fibres ◽  
Flexural Tensile Strength ◽  
Oriented Parallel ◽  
Concrete Casting

The aim of the research programme was to investigate flexural behaviour of steel fibre reinforced self-com­pacting concrete (SFRSCC). The specimens were in a form of slabs reinforced with steel fibres (of three lengths and two shapes) by volumes of 1.0% and 1.5%. Two methods of casting slabs were examined. The experimental tests per­formed on 80 specimens cut from slabs (1.2×1.2×0.15 m) involved tests of mechanical properties, digital image analysis (DIA), and X-ray computed tomography (XCT) procedures. Determination of distribution of fibres by DIA and XCT was required to assess relationships between mechanical properties and the casting methods. The tests were conducted according to RILEM TC 162-TDF (2002) and EN 14651:2005+A1:2007(E) recommendations. The study confirmed the technological problems associated with uneven distribution of steel fibres in SCC matrix. Based on the performed analy­sis, the flexural tensile strength of SFRSCC cannot be described with the formulas used for SFRC. Fibres are generally oriented parallel to the direction of concrete mixture flow in a mould. This phenomenon is influenced by fibre length and the location of concrete casting point (CCP). It was also demonstrated that the flexural behaviour of tested elements is influenced by CCP.

scholarly journals LARVA OF CHRYSOMELA CLIVICOLLIS, Kirby

1885 ◽  
Vol 17 (1) ◽  
pp. 19-19 ◽  
Author(s):  
G. H. French
Keyword(s):  
Anterior Part ◽  
Posterior Edge ◽  
Black Spots

Length .30 of an inch; abdomen nearly globular, flattened beneath; head and thorax narrow. Head pale grayish yellow; thorax and abdomen pale gray, a dorsal blackish line on the abdomen and a transverse stripe of the same on the thorax. Stigmata black, legs pale, the articulations dark; two black spots on each side of the head. Body smooth, shinine, a few hairs on the anterior part.Chrysalis.—Length .40 of an inch; thorax, wing and leg cases rose pink, as also the under side of abdomen; upper side of abdomen pinkish gray with a dorsal pink line. Stigmata black. Each joint of abdomen has a transverse row of black points on its posterior edge.

scholarly journals A Comparison of the Compositional, Microstructural, and Mechanical Characteristics of Ni-Free and Conventional Stainless Steel Orthodontic Wires

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3424
Author(s):  
Daniela Brüngger ◽  
Theodoros Koutsoukis ◽  
Youssef S. Al Jabbari ◽  
Monika Hersberger-Zurfluh ◽  
Spiros Zinelis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Elemental Composition ◽  
Indentation Modulus ◽  
Limited Information ◽  
X Ray Diffraction ◽  
Orthodontic Wires ◽  
Promising Alternative ◽  
X Ray ◽  
Oriented Parallel

Ni-free orthodontic wires were introduced to mitigate concerns associated with the use of Ni-containing alloys in orthodontics. However, limited information is available on their properties and therefore, the aim of this study was to characterize the elemental composition, the microstructure, and the mechanical properties of Ni-free orthodontic wires and compare them with their stainless steel (SS) counterparts. Four Ni-free and four conventional SS wires were included in this study. All the wires were initially imaged with a Scanning Electron Microscopy (SEM) and their elemental compositions were determined by X-ray Energy Dispersive Spectroscopy (EDX). Then, their microstructure was assessed by X-ray Diffraction (XRD) and the indentation modulus, elastic index, Martens Hardness and Vickers Hardness by Instrumented Indentation Testing (IIT). All the wires demonstrated surface cracks and pores oriented parallel to their long axis. The elemental composition of Ni-free alloys showed an increased Mn and Cr content while both SS and Ni-free wires shared the same dominant austenite structure. In conclusion, despite the differences in elemental composition, Ni-free wires demonstrated a similar microstructure and comparable mechanical properties with their conventional SS counterparts and thus may be considered as a promising alternative for patients with Ni supersensitivity.

scholarly journals Determination of the anisotropic fatigue behaviour of additively manufactured structures with short-time procedure PhyBaLLIT

2018 ◽  
Vol 165 ◽  
pp. 02006 ◽  
Author(s):  
Bastian Blinn ◽  
Marcus Klein ◽  
Tilmann Beck
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Vertical Direction ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Special Focus ◽  
Component Design ◽  
Physically Based ◽  
Manufacturing Techniques ◽  
Oriented Parallel

Additive Manufacturing techniques provide completely new possibilities in component design and creation of innovative material structures. To utilize the whole potential of Additive Manufacturing, the microstructure, the mechanical properties and their interrelations as well as their relationship to the Additive Manufacturing process parameters are essential. Investigations of the fatigue behaviour of additively manufactured (AM-) metallic materials are still available in limited extent. However, as a prerequisite for efficient and reliable use of AM-components in safety relevant structures, sound knowledge of fatigue behaviour and properties of these structures is indispensable. A central aspect in Additive Manufacturing is the anisotropic mechanical behaviour under monotonic and cyclic loading in dependency on the building direction [1, 2]. In the present work, the microstructure and mechanical properties of Selective Laser Melted (SLM) as well as Laser Deposition Welded (LDW) AISI 316L stainless steel specimens are investigated with special focus on the influence of the building direction. The investigated specimens are built in horizontal and vertical direction, resulting in layer planes oriented parallel and perpendicular to the loading direction, respectively. The fatigue tests have been performed on a servohydraulic testing system with measurement of stress-strain-hysteresis as well as of plastic deformation induced changes in temperature and specific electrical resistance. S-Nf-curves in the HCF-regime of AM-specimens have been determined with the time and material efficient Physically Based Lifetime calculation procedure PhyBaLLIT [3]. Anisotropic fatigue behaviour of the different AM-specimens has been rated with load increase tests (LIT) and the usage of S-Nfcurves calculated by the PhyBaLLIT method.

scholarly journals Shape in relation to fine structure in the bristles of Drosophila melanogaster

1945 ◽  
Vol 132 (869) ◽  
pp. 396-423 ◽  
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Drosophila Melanogaster ◽  
Fine Structure ◽  
Anisotropic Medium ◽  
Mode Of Action ◽  
Close Correspondence ◽  
Yield Value ◽  
Optical And Mechanical Properties ◽  
Oriented Parallel

The bristles of Drosophila melanogaster have provided material for a study of the relation between the shape of a specialized type of cell and the orientation of the chitin molecules of the cell wall, as revealed by optical and mechanical properties. Close correspondence between shape and orientation has been found, both in normal and mutant bristles. Certain of the mechanical properties of the wall of the adult bristle can be studied directly, and something of those of the immature wall can be inferred from the behaviour of the bristle during develop­ment. There is reason to believe that the newly formed wall is plastic and that it possesses a definite yield value. The bristle may be regarded as a hollow object blown in a plastic, anisotropic medium by the pressure of cytoplasm formation in the trichogen. It seems reasonable to suppose that the shape of the normal bristle is intimately related to the growth in length of the chitin chains of the cell wall oriented parallel to the long axis of the cell. Indeed the long axis appears to be such because the oriented chains grow in its direction. Our study of mutant as well as normal bristles has enabled us to make a tentative analysis of the factors concerned in their growth, and to suggest what may be the mode of action of those genes which modify the shape of the bristle. We are led to an interpretation of the shape of the bristle in terms of the properties of the substances secreted by the trichogen (wall-substance and cytoplasm) and of the time relations of their synthesis.

Shell implosion depth and implosion morphologies in three species of Sepia (Cephalopoda) from the Mediterranean Sea

1984 ◽  
Vol 64 (4) ◽  
pp. 955-966 ◽  
Author(s):  
Peter D. Ward ◽  
Sigurd Von Boletzky
Keyword(s):  
Mechanical Properties ◽  
Soft Tissue ◽  
Mediterranean Sea ◽  
Tissue Damage ◽  
Anterior Part ◽  
Ambient Pressure ◽  
Soft Tissue Damage ◽  
The Mediterranean ◽  
Embryonic Region ◽  
Juvenile Shell

The maximum habitation depths of chambered cephalopods are dictated by the mechanical properties of the shell. All chambered cephalopods have a depth at which ambient pressure is sufficient to implode the gas-filled shell portions. Experiments on Sepia elegans D'Orbigny, S. officinalis Linne and S. orbignyana Férussac from the Mediterranean Sea show these three species to have differing depth limits and modes of shell implosion. Large S. officinalis implode between 150 and 200 m, whereas newly hatched and advanced embryonic specimens implode between 50 and 100 m. The larger S. officinalis are occasionally caught at depths greater than the implosion depth of the juvenile shell parts. They apparently avoid implosion of the early shell portions by refilling these first-formed chambers with cameral liquid later in life. Implosion in S. officinalis generally resulted in the crushing of all or most of the septa in a band extending from the embryonic region to the anterior part of the shell. Implosion was generally accompanied by fatal rupture of underlying tissue into the implosion zones. Implosion of S. orbignyana occurred between 550 and 600 m and was very different in form from that in S. officinalis, occurring mostly within the smooth zone of the last-formed several chambers, and rarely extending back into the siphuncular region (striae zone). Increasing depth caused episodic implosion of sequentially older chambers in the smooth zone. The shallower implosions were accompanied by little soft-tissue damage. Massive internal injury only occurred in the deepest implosions (700 m or greater). Implosion in S. elegans occurred betw en 400 and 600 m. Too few specimens were available to allow generalizations about morphology of implosion in this species.

Local Stiffness in Nylon 6/Rubber Blends Determined by Digital Pulsed Force Mode-SPM

2005 ◽  
Vol 11 (S03) ◽  
pp. 134-137 ◽  
Author(s):  
M. G. Segatelli ◽  
C. A. R. Costa ◽  
F. Galembeck ◽  
M. C. Goncalves
Keyword(s):  
Mechanical Properties ◽  
Polymer Blends ◽  
Polymer Blend ◽  
Binary Blends ◽  
Rubber Blends ◽  
Thermoplastic Matrix ◽  
Force Mode ◽  
Two Phases ◽  
Local Stiffness ◽  
Soft Rubber

The incorporation of soft rubber into a thermoplastic matrix can lead to tough blends. Generally, such binary blends are immiscible and exhibit poor mechanical properties caused by the unfavorable interactions between the two phases. Thus, there is an enormous interest in polymer blend compatibility to improve the properties of the polymer blends by the addition of an appropriate compatibilizer [1,2].

scholarly journals Bulk chemical composition contrast from attractive forces in AFM force spectroscopy

2021 ◽  
Vol 12 ◽  
pp. 58-71
Author(s):  
Dorothee Silbernagl ◽  
Media Ghasem Zadeh Khorasani ◽  
Natalia Cano Murillo ◽  
Anna Maria Elert ◽  
Heinz Sturm
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Chemical Characterization ◽  
Structure Property ◽  
Complete Structure ◽  
Force Microscopy ◽  
Property Correlation ◽  
Force Curves ◽  
Bulk Chemical ◽  
Local Stiffness

A key application of atomic force microscopy (AFM) is the measurement of physical properties at sub-micrometer resolution. Methods such as force–distance curves (FDCs) or dynamic variants (such as intermodulation AFM (ImAFM)) are able to measure mechanical properties (such as the local stiffness, k r) of nanoscopic heterogeneous materials. For a complete structure–property correlation, these mechanical measurements are considered to lack the ability to identify the chemical structure of the materials. In this study, the measured attractive force, F attr, acting between the AFM tip and the sample is shown to be an independent measurement for the local chemical composition and hence a complete structure–property correlation can be obtained. A proof of concept is provided by two model samples comprised of (1) epoxy/polycarbonate and (2) epoxy/boehmite. The preparation of the model samples allowed for the assignment of material phases based on AFM topography. Additional chemical characterization on the nanoscale is performed by an AFM/infrared-spectroscopy hybrid method. Mechanical properties (k r) and attractive forces (F attr) are calculated and a structure–property correlation is obtained by a manual principle component analysis (mPCA) from a k r/F attr diagram. A third sample comprised of (3) epoxy/polycarbonate/boehmite is measured by ImAFM. The measurement of a 2 × 2 µm cross section yields 128 × 128 force curves which are successfully evaluated by a k r/F attr diagram and the nanoscopic heterogeneity of the sample is determined.

Strain parameters at hot rolling of aluminum strips reinforced with steel netting

2018 ◽  
Vol 22 (6) ◽  
pp. 2009-2029 ◽  
Author(s):  
M Stolbchenko ◽  
H Makeieva ◽  
O Grydin ◽  
Ya Frolov ◽  
M Schaper
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Tensile Strain ◽  
Rolling Direction ◽  
Aluminum Matrix ◽  
Tension Tests ◽  
Temperature And Pressure ◽  
Oriented Parallel ◽  
Reducing Properties ◽  
Properties Of Composites

This experiment studied the strain parameters of rolling an aluminum matrix when wire netting is inserted between aluminum layers. During the experiment, two types of stainless steel fabric netting oriented parallel and diagonal to the rolling axis were placed between two aluminum strips and rolled. Multiple rolling processes were performed in which the temperature and pressure on the material were varied to produce bonding of matrix layers. During the study, the following main investigations were made: strain on areas of longitudinal and transverse cross sections of the composite was measured; stretching and ovalization of net wiring and changes in the net cell angles were determined; mechanical properties of composites along the rolling direction were tested. The main contradiction resulting from this experiment was as follows: the contact pressure required for the bonding of aluminum layers produces extreme tensile strain on the inserted net wires, reducing the mechanical properties of the reinforcing net and thus reducing properties of the entire composite. Optimal results in the longitudinal tension tests were achieved by using strips with diagonally oriented net-reinforcement.

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