Temperature-dependent dielectric properties of slightly hydrated horn keratin

Rizvi, Tasneem Zahra; Khan, Muhammad Abdullah

doi:10.1016/j.ijbiomac.2008.01.001

Cited by 22 publications

(12 citation statements)

References 43 publications

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“…The fracture toughness of the horn sheaths of gemsbok (Oryx gazella), mouflon (Ovis aries musimon) and waterbuck (Kobus ellipsiprymnus) were systematically measured as a function of water and, interestingly, the results were applied to understand the horning behavior of bovids (Leuthold, 1977;Kitchener, 1987b). Furthermore, the dielectric properties of the horn sheaths of calf, cow and rhinoceros were also studied (Maeda, 1989;Marzec and Kubisz, 1997;Rizvi and Khan, 2008). The knowledge of the mechanical properties of bovid horns is helpful for gaining a deeper understanding of their natural design and adaptation of their structures and functions.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the mechanical properties of the horn sheaths from cattle

Zhao

Feng

et al. 2010

Journal of Experimental Biology

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SUMMARYBovine horn is composed of a sheath of keratin overlying a bony core. Previous studies of the bovine horn sheath have focused mainly on its morphology and compositions. In the present paper, we performed a series of uniaxial tension, three-point bending, and fracture tests to investigate the structural and mechanical properties of the horn sheaths from subadult cattle, Bos taurus. The effects of hydration on the mechanical properties were examined and their variations along the longitudinal direction of the horn sheath were addressed. Scanning electron microscopy of the fracture surfaces showed that the horn sheath has a layered structure and, more interestingly, the laminae have a rippled appearance. The Young's modulus and tensile strength increase from 850MPa and 40MPa at 19% water content to 2.3GPa and 154MPa at 0% water content, respectively. The Poisson's ratio of the horn sheath was about 0.38. The critical stress intensity factor was about 4.76MPam 1/2 at an intermediate hydration (8% water content), greater than that at 0% water content (3.86MPam 1/2 ) and 19% water content (2.56MPam 1/2 ). The bending properties of the samples varied along the length of the horn. The mean flexural moduli of the specimens in the distal, middle and proximal parts were about 6.26GPa, 5.93GPa and 4.98GPa, respectively; whereas the mean yield strength in the distal segment was about 152.4MPa, distinctly higher than that in the middle (135.7MPa) and proximal parts (116.4MPa). This study deepens our understanding of the relationships among optimal structure, property and function of cattle horn sheaths.

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Section: Introductionmentioning

confidence: 99%

Experimental study on the mechanical properties of the horn sheaths from cattle

Zhao

Feng

et al. 2010

Journal of Experimental Biology

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“…Rizvi and Khan have investigated the frequency and temperature dependence of dielectric constant and loss factor in cow horn keratin [3]. Kumar and Boopathy have studied mechanical and thermal properties of defatted oxen horn fibre reinforced PP composites and observed that 15 % of horn fibre particles gave optimum results [4].…”

Section: Investigation Of Mechanical Properties Of Horn Powder-filledmentioning

confidence: 99%

Investigation of Mechanical Properties of Horn Powder-Filled Epoxy Composites

Kumar¹,

Boopathy²,

Dharmalingam³

et al. 2017

SV-JME

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“…For a keratin-air-glass system, we use the relative permittivity of bovine β-keratin from the horn, 1 = 20 [41,42], and the refractive index from tortoise-shell keratin, n 1 = 1.55 [43, p. 8]. The surface is taken to be a soda lime glass ( 2 = 8; n 2 = 1.5) and the medium is air ( 3 ,n 3 ≈ 1).…”

Section: Appendix D: Hamaker Constant For Keratin-glass Interactionsmentioning

confidence: 99%

Metastable states and activated dynamics in thin-film adhesion to patterned surfaces

2014

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We consider adhesion due to London-van der Waals attraction between a thin film and a patterned surface with nanometer asperities. Depending on the surface topography and the stiffness of the film, three regimes of adhesion are identified: complete contact adhesion, partial contact adhesion, and glassy adhesion. For complete contact adhesion, the film conforms to the undulations of the surface, whereas for partial contact and glassy adhesion, the adhesive interface breaks down into microscopic areas of contact. When a film in the glassy regime is peeled off the surface, metastable states develop at which the crack front becomes arrested, analogously to the frustrated motion of the three-phase contact line across a heterogeneous surface. For this glassy regime, we use transition state theory to model the thermally activated progression of the crack front. This theoretical treatment suggests that the rate of the adhesive failure increases exponentially with the applied force.

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Temperature-dependent dielectric properties of slightly hydrated horn keratin

Cited by 22 publications

References 43 publications

Experimental study on the mechanical properties of the horn sheaths from cattle

Experimental study on the mechanical properties of the horn sheaths from cattle

Investigation of Mechanical Properties of Horn Powder-Filled Epoxy Composites

Metastable states and activated dynamics in thin-film adhesion to patterned surfaces

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