CROSS-LINKS MULTISCALE EFFECTS ON BONE ULTRASTRUCTURE BIOMECHANICAL BEHAVIOR

2018 ◽  
Vol 18 (06) ◽  
pp. 1850062
Author(s):  
TESNIM KRAIEM ◽  
ABDELWAHED BARKAOUI ◽  
TAREK MERZOUKI ◽  
MOEZ CHAFRA
Keyword(s):  
Mechanical Behavior ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Organic Matrix ◽  
The Other ◽  
Biomechanical Behavior ◽  
Collagen Molecules ◽  
Cross Links ◽  
Bone Ultrastructure ◽  
The Cross

Bone is a multiscale combination of collagen molecules merged with mineral crystals. Its high rigidity and stability stem amply from its polymeric organic matrix and secondly from the connections established between interdifferent and intradifferent scale components through cross-links. Several studies have shown that the cross-links inhibition results in a reduction in strength of bone but they do not quantify the degree to which these connections contribute to the bone rigidity and toughness. This report is classified among the few works that measure the cross-links multiscale impact on the ultrastructure bone mechanical behavior. This work aims firstly to study the effect of cross-links at the molecule scale and secondly to gather from literature studies results handling with cross-links effects on the other bone ultrastructure scales in order to reveal the multiscale effect of cross-links. This study proves that cross-links increasing number improves the mechanical performance of each scale of bone ultrastructure. On the other hand, cross-links have a multiscale contribution that depends on its rank related to existing cross-links connecting the same geometries and it depends on mechanical characteristics of geometries connected.

scholarly journals Different structural states of a microtubule cross-linking molecule, captured by quick-freezing motile axostyles in protozoa.

1986 ◽  
Vol 103 (6) ◽  
pp. 2209-2227 ◽  
Author(s):  
J E Heuser
Keyword(s):  
Active Role ◽  
Longitudinal Shear ◽  
The Other ◽  
Cross Bridge ◽  
Other Hand ◽  
Quick Freezing ◽  
Cross Links ◽  
Dynein Arms ◽  
The Cross ◽  
Cross Bridges

Freeze-etch preparation of the laminated bundles of microtubules in motile axostyles demonstrates that the cross-bridges populating individual layers or laminae are structurally similar to the dynein arms of cilia and flagellae. Also, like dynein, they are extracted by high salt and undergo a change in tilt upon removal of endogenous ATP (while the axostyle as a whole straightens and becomes stiff). On the other hand, the bridges running between adjacent microtubule laminae in the axostyle turn out to be much more delicate and wispy in appearance, and display no similarity to dynein arms. Thus we propose that the internal or "intra-laminar" cross-bridges are the active force-generating ATPases in this system, and that they generate overall bends or changes in the helical pitch of the axostyle by altering the longitudinal and lateral register of microtubules in each lamina individually; e.g., by "warping" each lamina and creating longitudinal shear forces within it. The cross-links between adjacent laminae, on the other hand, would then simply be force-transmitting elements that serve to translate the shearing forces generated within individual laminae into overall helical shape changes. (This hypothesis differs from the views of earlier workers who considered a more active role for the later cross-links, postulating that they cause an active sliding between adjacent layers that somehow leads to axostyle movement.) Also described here are physical connections between adjacent intra-laminar cross-bridges, structurally analogous to the overlapping components of the outer dynein arms of cilia and flagella. As with dynein, these may represent a mechanism for propagating local changes from cross-bridge to cross-bridge down the axostyle, as occurs during the passage of bends down the length of the organelle.

scholarly journals Comparative studies of the cross-linked regions of elastin from bovine ligamentum nuchae and bovine, porcine and human aorta

1975 ◽  
Vol 149 (3) ◽  
pp. 685-695 ◽  
Author(s):  
G E Gerber ◽  
R A Anwar
Keyword(s):  
The Other ◽  
Striking Difference ◽  
Human Aorta ◽  
Amino Group ◽  
Edman Degradation ◽  
Oxidative Deamination ◽  
Hydrophobic Residues ◽  
Pyridinium Ring ◽  
Cross Links ◽  
The Cross

1. The preparative Edman degradation of desmosine-containing peptides permitted the isolation of peptides C-terminal to the desmosine cross-links in bovine, porcine and human aortic elastin as well as bovine ligamentum nuchae elastin. This identifies the lysines in the tropoelastin which give rise to the desmosine cross-links. 2. The sequences from bovine aortic elastin were identical with those obtained from bovine ligamentum nuchae elastin but differed from those obtained from the other species. The most striking difference involves the occurrence of phenylalanine in bovine elastin and tyrosine in porcine and human elastin C-terminal to the desmosine cross-links. 3. The sequences of the C-terminal peptides were found to fall into two distinct classes, one starting with hydrophobic residues, the other starting with alanine. It is proposed that thehydrophobic residue prevents the enzymic oxidative deamination of the adjacent lysine e-amino group and this then contributes the nitrogen to the pyridinium ring of the cross-links.

scholarly journals Shear Strength Enhancement of Cemented Reinforced Sand: Role of Cement Content on the Macro-Mechanical Behavior

2019 ◽  
Vol 41 (4) ◽  
pp. 200-211 ◽  
Author(s):  
Kheira Boutouba ◽  
Ismail Benessalah ◽  
Ahmed Arab ◽  
Ahmed Djafar Henni
Keyword(s):  
Shear Strength ◽  
Mechanical Behavior ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Cement Content ◽  
Reinforced Sand ◽  
Hydraulic Binder ◽  
Cure Time ◽  
Effective Role ◽  
Direct Shear Apparatus

Abstract Sands reinforced by hydraulic binders (cement) have constituted in recent decades a major asset for the expansion of several areas of engineering. The mechanical behavior of sand-cement mixtures has undergone some controversies studied on the Chlef sand. In this paper, we present an experimental study to investigate the mechanical behavior of a sandy soil reinforced by a hydraulic binder (cement), using the direct shear apparatus emphasizing on the shear strength characteristics and the vertical deformation variation of cemented reinforced sand. The parameters used in this study are mainly: relative density (Dr = 80%), normal stress (σn = 100, 200, 400 kPa), water content (3, 7 and 10%), cement content (2.5, 5, 7.5 and 10 %) and cure time (7, 14 and 28 days). The experimental results show that the mechanical characteristics in terms of internal cohesion (C) and internal frication angle (φ) give a better mechanical performance with the binder inclusion, and the cure conditions play an effective role on the improvement of the shear strength. This result also showed that 10% of the cement content gave us a maximum value of shear strength and an optimal influence on the mechanical characteristics. The addition of cement not only improves the shear strength of soil, but also provides diversity in the resistance against the deformations imposed load, which can be established by a dilatant character.

Investigate Mechanical Behavior of Gold Nanowire with Defect

2013 ◽  
Vol 481 ◽  
pp. 49-54
Author(s):  
Jia Lin Tsai ◽  
Cheng Fong Hong
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Mechanical Behavior ◽  
Cross Section ◽  
Md Simulation ◽  
The Other ◽  
Gold Nanowires ◽  
Gold Nanowire ◽  
Section Size ◽  
The Cross

This study aims to investigate the mechanical properties of gold nanowires using molecular dynamics (MD) simulation. The effects of the cross section size and the defects on the stress strain curves of the nanowires are examined. Moreover, the inception as well as the processing of dislocationin the nanowire is accounted by means of the centro-symmetry parameter and meanwhile, the energy variation during the dislocation is calculated. Results indicated for the pristine gold nanowire, as the cross section size increases, Youngs modulus increases, but the yielding stress decreases accordingly. Once the ultimate linear point is attained, the dislocation takes place abruptly from the nanowire surfaceand extended along the {111} planes. On the other hand, for the nanowire with defect, it was found that the dislocation is initiated from the defect which can significantlyreduce the yielding stress of the nanowires.

Biopolymer Based Tough and Self-Recovering Ionic-Covalent Entanglement Hydrogels

2014 ◽  
Vol 1685 ◽  
Author(s):  
Damian M. Kirchmajer ◽  
Marc in het Panhuis
Keyword(s):  
Tissue Engineering ◽  
Mechanical Behavior ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Gellan Gum ◽  
Soft Robotics

ABSTRACTEmerging applications for hydrogels such as soft robotics and tissue engineering require hydrogels with enhanced mechanical performance. We report the mechanical characteristics of two types of hydrogels: i) ionic-covalent entanglement (ICE) network hydrogels based on calcium cross-linked gellan gum and genipin cross-linked gelatin and ii) ICE microsphere reinforced gelatin hydrogels. This investigation showed that ICE gels can recover up 80% of their mechanical behavior during 5 repeated compressions. In addition, the optimum mechanical performance of gelatin reinforced gels was achieved with inclusion of 40% of ICE microspheres.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Weldability - Behavior of Welded Reinforcement

2019 ◽  
Vol 70 (10) ◽  
pp. 3469-3472
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Mechanical Characteristics ◽  
Mechanical Performance ◽  
Current Work ◽  
Carbon Equivalent ◽  
Work Process ◽  
Ultimate Limit

Weldability involves two aspects: welding behavior of components and safety in operation. The two aspects will be reduced to the mechanical characteristics of the elements and to the chemical composition. In the case of steel reinforcing rebar’s, it is reduces to the percentage of Cech(carbon equivalent) and to the mechanical characteristics: the yielding limit, the ultimate limit, and the elongations which after that represent the ductility class in which the re-bars is framed. The paper will present some types of steel reinforcing rebar’s with its mechanical characteristics and the welding behavior of those elements. In the current work, process-related behavior of welded reinforcement, joint local and global mechanical properties, and their correlation with behavior of normal reinforcement and also the mechanical performance resulted in this type of joints. Keywords: welding behavior, ultimate limit, reinforcing rebar’s

Getting Jesus off the altar: Undoing atonement readings in Revelation

2021 ◽  
Vol 118 (1) ◽  
pp. 54-61
Author(s):  
Anna M. V. Bowden
Keyword(s):  
The Other ◽  
History Of ◽  
The Cross

The interpretive history of Revelation is overrun with descriptions of Jesus as a sacrificial lamb. Yet, John never uses the popular phrase to describe him. By drawing attention to four significant omissions in the text, I argue against atonement readings of “the Lamb” in Revelation. Revelation is not a theological treatise on the meaning of the cross. It feeds questions about power and violence and admonishes the seven churches against participation in their imperial context. John’s slaughtered lamb, therefore, does not evoke a paschal sacrifice; it points to Rome’s penchant for violence. Joining the other bloodied bodies in Revelation, the lamb’s blood further incriminates Rome. Everywhere one looks in John’s depiction of empire, violence lurks. Finally, the only altar in Revelation is the heavenly altar, and this altar is not a place for sacrifice. The heavenly altar is a place where the laments of the suffering are heard, a place for worshipping God, and a place where Rome will meet its judgment. John’s Jesus is not a self-sacrificing spiritual savior; he bears witness to the bloodthirsty, massacre-loving beast-of-all-beasts. Churches must choose their allegiance.

Mechanical Behavior for some Cobalt Alloys

2015 ◽  
Vol 1114 ◽  
pp. 9-12
Author(s):  
Alexandru Ghiban ◽  
Brandusa Ghiban ◽  
Cristina Maria Borţun ◽  
Nicolae Serban ◽  
Mihai Buzatu
Keyword(s):  
Tensile Strength ◽  
Chemical Composition ◽  
Mechanical Behavior ◽  
Mechanical Characteristics ◽  
Fractographic Analysis ◽  
Cobalt Alloys ◽  
Dental Alloys ◽  
Bending Tests ◽  
Longitudinal Modulus

Four compositions of some usually commercial dental alloys were investigated in order to determine the mechanical characteristics and fractographic analysis of tensile and bending tests surfaces. A correlation between chemical composition (either molybdenum or molybdenum and chromium contents) and mechanical characteristics (longitudinal modulus, tensile strength and elongation) were finally done.

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