Engineering Materials and Their Properties

Ashby, Michael F.; Jones, David R.H.

doi:10.1016/b978-0-08-096665-6.00001-5

Cited by 141 publications

(147 citation statements)

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“…This suggests that the exceptional rigidity of the intrasheet interface is defined largely by sequence-independent, intermolecular hydrogen bonding with sidechain-sidechain interactions (van der Waals, hydrophobic) playing only a minor role in stabilizing the fibrils' constituent β-sheets (25,18). Indeed, the intrasheet bonding stiffness, k intrasheet = 2:0 ± 0:5 N/m, is identical to the bond stiffness of other cooperatively hydrogen-bonded materials (k H-bond = 2 − 3 N/m), such as ice (26,27). It is important to note that although the intrasheet bond stiffness, k intrasheet , in mature fibrils arises mainly from generic interbackbone hydrogen bonding, the relative propensity to form such filamentous aggregates will vary with sequence (28).…”

Section: Significancementioning

confidence: 69%

“…Because interatomic bond stiffness largely determines mechanical stiffness (26), the exceptional rigidity of amyloid (18,22,29) derives overwhelmingly from a longitudinal, interbackbone hydrogen-bonding network with lateral, intersidechain, and electrostatic interactions almost 20 times less important. Such a large degree of anisotropy leads to length-dependent mechanical properties of amyloid (Fig.…”

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confidence: 99%

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Nanomechanics and intermolecular forces of amyloid revealed by four-dimensional electron microscopy

Fitzpatrick

Vanacore

Zewail

2015

Proc. Natl. Acad. Sci. U.S.A.

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The amyloid state of polypeptides is a stable, highly organized structural form consisting of laterally associated β-sheet protofilaments that may be adopted as an alternative to the functional, native state. Identifying the balance of forces stabilizing amyloid is fundamental to understanding the wide accessibility of this state to peptides and proteins with unrelated primary sequences, various chain lengths, and widely differing native structures. Here, we use four-dimensional electron microscopy to demonstrate that the forces acting to stabilize amyloid at the atomic level are highly anisotropic, that an optimized interbackbone hydrogen-bonding network within β-sheets confers 20 times more rigidity on the structure than sequence-specific sidechain interactions between sheets, and that electrostatic attraction of protofilaments is only slightly stronger than these weak amphiphilic interactions. The potential biological relevance of the deposition of such a highly anisotropic biomaterial in vivo is discussed.T he intricate interplay of intermolecular forces stabilizing amyloid at the atomic level has yet to be fully elucidated (1). Amyloid fibrils are narrow (70-200 Å), elongated (1-3 μm), twisted (pitch ∼ 1,000 ± 500 Å) aggregates containing a universal "cross-β" core structure (2) composed of arrays of β-sheets running parallel to the long axis of the fibrils (3). Their hierarchical structure is stabilized by three main protein-protein interfaces: (i) stacking of hydrogen-bonded β-strands within a single β-sheet (intrasheet), (ii) cross-β-sheet packing into a multisheet protofilament (intersheet), and (iii) lateral association of protofilaments (interprotofilament) (4). Each of these packing interfaces gives rise to characteristic diffraction pattern reflections corresponding to the intrasheet (4.8 Å), intersheet (8-12 Å, depending on sidechain volume), and interprotofilament (determined by chain length) spacings (5).By applying a laser-induced, temperature (T-) jump to amyloid, we can infinitesimally expand the material, thereby probing the intermolecular forces acting across each of the packing interfaces (6). Static, global heating, particularly of amyloid-like microcrystals (7), disrupts molecular structure, precluding such delicate perturbations. To capture the rapid expansion and recovery of an amyloid specimen, a precisely timed, pulsed (probe) electron beam, following the laser (pump) pulse, is used to generate a series of time-resolved diffraction patterns. By accurately measuring the movement ðΔxÞ of the reflection (initially occurring at an equilibrium separation, x e ) upon initiation of the ultrafast temperature jump, we determine the relative expansion, or strain, e = Δx=x e . Atomistic simulations predict that the stretching elasticity of amyloid is linear for strains up to only e ∼ 0:1%, i.e., 10 −3 (8). The exquisite sensitivity and high spatiotemporal resolution of four-dimensional (4D) electron microscopy (9, 10) enables us to measure such minute deformations and directly probe, at the atom...

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Section: Significancementioning

confidence: 69%

mentioning

confidence: 99%

Nanomechanics and intermolecular forces of amyloid revealed by four-dimensional electron microscopy

Fitzpatrick

Vanacore

Zewail

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…The material is modeled as linearly elastic and perfectly plastic with a Young's modulus of 70GP a and a Poisson's ratio of 0.35 [33]. The yield stress is taken to be 275M P a based on the experiments and is in agreement with available material data [39]. The applied experimental loading is approximated by fixing the translation at one edge and specifying a static displacement at the opposite edge.…”

Section: Reserved For Publication Footnotesmentioning

confidence: 97%

Low Porosity Metallic Periodic Structures with Negative Poisson's Ratio

et al. 2013

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Auxetic behavior in low porosity metallic structures is demonstrated via a simple system of orthogonal elliptical voids. In this minimal 2D system, the Poisson's ratio can be effectively controlled by changing the aspect ratio of the voids. In this way, large negative values of Poisson's ratio can be achieved, indicating an effective strategy for designing auxetic structures with desired porosity.

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“…4 Consequently, the increase in the modulus of the inclusions, both by stretching and/or rotation, leads to an increase in the modulus of the whole matrix; as it is well known in the mechanical properties of composite and two-phase materials. 2,3,22 It is convenient to mention here that the viscosity of the HAO (type DEA) oil is high enough at both the frequency (… 2 Hz) and temperature 300.0 K (AE0:3 K) used in the present work, in such a way that this phase in the SBR 1712 composite samples can be considered as a viscoelastic solid. 4,16 The behavior of tan( Þ curves as a function of the applied electric field for SBR 1712 composite samples follows the usual trend earlier reported for DMA experiments conducted under high electrical field.…”

Section: The New Modelmentioning

confidence: 99%

Electric memory effects in styrene-butadiene rubber, containing electric inclusions of highly aromatic oil

et al. 2018

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It was determined that samples of styrene-butadiene rubber (SBR), containing highly aromatic oil, exhibit memory effects giving rise to dynamic elastic modulus, damping and internal stresses degree which can be tailored depending on the applied electric field strength. The capability and stability of the interaction process between aligned neighbor dipoles for exhibiting a memory effect, once the aligning electric field was removed are studied. It is determined that depending on the spatial arrangement and the amount of electric charge of the dipoles, this interaction is able to promote a memory effect which keeps the alignment between them. This electrostatic interaction plays the role of a counteracting effect for keeping the alignment, which was called electroelasticity. The results from the developed model were applied successfully to SBR composite samples for explaining the memory effects recorded from dynamic mechanical analysis (DMA) measurements under electric field. In addition, the model of the electric inclusion based on the inclusion theory for continuous media, was applied to determine the degree of internal stresses in the dielectric composite material due to the external applied electric field. In addition, from the coupling between the model developed here and simple issues related to the mechanical properties of composite materials, a procedure for determining the maximum possible gap between the electric dipoles in composite dielectric materials is also shown.

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Engineering Materials and Their Properties

Cited by 141 publications

References 0 publications

Nanomechanics and intermolecular forces of amyloid revealed by four-dimensional electron microscopy

Nanomechanics and intermolecular forces of amyloid revealed by four-dimensional electron microscopy

Low Porosity Metallic Periodic Structures with Negative Poisson's Ratio

Electric memory effects in styrene-butadiene rubber, containing electric inclusions of highly aromatic oil

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