The Mechanical Properties of the Cell Surface

1955 ◽  
Vol 32 (4) ◽  
pp. 734-750 ◽  
Author(s):  
J. M. MITCHISON ◽  
M. M. SWANN
Keyword(s):  
Cell Surface ◽  
Young’S Modulus ◽  
Sea Water ◽  
Young's Modulus ◽  
Contractile Ring ◽  
A Value ◽  
Sudden Rise ◽  
Slow Rise ◽  
Stage Yield ◽  
Sperm Aster

1. Measurements with the cell elastimeter on the stiffness of the cell membrane of fertilized sea-urchin eggs show the following general features. There is a sudden rise at fertilization, followed by a fall during the early sperm aster stage to the lowest value reached during development (a Young's modulus of about 0.58 x 104 dynes/cm.2). The stiffness rises slowly until metaphase, after which it rises rapidly to reach a maximum during late anaphase and early cleavage (6.81 x 104 dynes/cm.2). During the later stages of cleavage the stiffness falls again and reaches a value in the second interphase which is about twice as high as in the first interphase. Masurements on naked eggs in calcium-free sea water indicate that the slow rise in metaphase is due to the development of the hyaline layer. 2. Measurements on swollen and shrunken eggs at cleavage indicate that there is no interal pressure in the eggs at this stage, but similar experiments with eggs at the sperm aster stage yield anomalous results. Observations on the wrinkling point in shrunken eggs show that the maximum possible internal pressure is 19 dynes/cm.2 for sperm aster eggs and 500 dynes/cm.2 for cleaving eggs. 3. The bearing of these results on various theories of the mechanism of cleavage is briefly discussed. The rise in Young's modulus of the whole cell surface at cleavage argues against theories depending on the action of the spindle and asters, and against theories proposing a contractile ring in the surface. The rise is, however, what might be expected on the basis of the expanding membrane theory.

Round-Robin Tests of Modulus and Strength of Polysilicou

1998 ◽  
Vol 518 ◽  
Author(s):  
W. N. Sharpe ◽  
S. Brown ◽  
G. C. Johnson ◽  
W. Knauss
Keyword(s):  
North Carolina ◽  
Failure Analysis ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Research Society ◽  
Test Methods ◽  
Society Meeting ◽  
A Value ◽  
Production Run ◽  
Materials Research

AbstractThe Young's modulus and strength of polysilicon specimens manufactured in the same production run were measured in four different laboratories. Specimens subjected to in-plane bending were tested at U. C. Berkeley and at Failure Analysis Associates, and tensile measurements were made at Caltech and Johns Hopkins. All specimens were produced at the Microelectronics Center of North Carolina (MCNC).In bending, the Young's modulus for specimens nominally 2 µm thick was measured as 174 GPa and 137 GPa; whereas in tension, a value of 132 GPa was obtained. Modulus values of 136 GPa and 142 GPa were measured in tension on specimens nominally 1.5 µm and 3.5 µm thick. Strengths of the brittle polysilicon were 2.8 and 2.7 GPa in bending and 1.3 GPa for both thicknesses in tension.These preliminary results were presented at Symposium N - Microelectromechanical Structures for Materials Research at the Materials Research Society meeting in April 1998. This paper is a short overview of the test methods — each of which is described elsewhere — and a documentation of the results presented at that time.

Direct Measurements of the Stiffness of Echinoderm Sperm Flagella

1979 ◽  
Vol 79 (1) ◽  
pp. 235-243 ◽  
Author(s):  
MAKOTO OKUNO ◽  
YUKIO HIRAMOTO
Keyword(s):  
Young’S Modulus ◽  
Inorganic Phosphate ◽  
Sea Water ◽  
Flexural Rigidity ◽  
Young's Modulus ◽  
Entire Length ◽  
Free Solution ◽  
Direct Measurements ◽  
Hemicentrotus Pulcherrimus

1. The stiffness (flexural rigidity) of some echinoderm sperm flagella was measured, using a flexible glass microneedle. 2. Values of 0.3-1.5 × 10−21 N m2 were obtained for the stiffness of live flagella which were immobilized with CO2-saturated sea water. 3. The immobilized live flagellum was uniform in stiffness along its entire length, except in a particular plane of imposed bending in which flexible regions were observed. 4. Demembranated flagella (Hemicentrotus pulcherrimus) in an ATP-free solution were about ten times stiffer (1.1 × 10−20 N m2) than immobilized live ones (0.5-0.9 × 10−21 N m2). The stiffness was decreased by addition of ATP to the solution and became equivalent to that of live ones when the solution contained 10 mM ATP. 5. In the demembranated flagella, the effects of ADP and ATP on the stiffness were similar. Other nucleotide phosphates and inorganic phosphate did not reduce the stiffness. 6. Young's modulus of microtubules is estimated to be 2.5 × 109 Nm2 on the basis that the microtubules have no tight connexion with one another in immobilized live flagella.

First principles calculation of the elastic constants of intermetallic compounds: metastable Al3Li

1991 ◽  
Vol 6 (2) ◽  
pp. 324-329 ◽  
Author(s):  
X-Q. Guo ◽  
R. Podloucky ◽  
A.J. Freeman
Keyword(s):  
Young’S Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Local Density ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
First Principles Calculation ◽  
Full Potential ◽  
A Value ◽  
Experimental Values

We report first principles local density calculations for the metastable Al3Li intermetallic compound with cubic L12 crystal structure using the full-potential linearized augmented plane wave method. From the second derivative of the total energy as a function of volume, and generated tetragonal and trigonal lattice distortions, the elastic constants C11, C12, and C44 were derived yielding C11 = 158 GPa, C12 = 29.4 GPa, and C44 = 57.7 GPa. Because of the very high Young's modulus (E = 141 GPa) compared, for example, to pure Al (E = 66 GPa), it is suggested that Al3Li plays an important role in strengthening the Al–Li alloys. The calculated Young's modulus appears in good agreement with experimental estimates when the experimental values are extrapolated to 0 K. Although the Young's modulus of Al3Li is increased in comparison to Al, the calculated bulk modulus is decreased to a value of 72 GPa as compared to pure Al (82 GPa), in agreement with experiment. As a result, the Poisson ratio is reduced to ŝ = 0.173 as compared to the value 1/3 for an isotropic medium. Because of this and the high Young's modulus, the calculated Debye temperature ΘD at 0 K amounts to 672 K, which is substantially larger than ΘD for Al, which is about 400 K.

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

2019 ◽  
Vol 107 (2) ◽  
pp. 207 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Miroslav Karlík ◽  
Veronika Kadlecová ◽  
Jiří Čapek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Milling Time ◽  
Young's Modulus ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Particles ◽  
Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

Degradation of Rocks, Through Cracking Caused by Differential Thermal Expansion, in Relation to Nuclear Waste Repositories

1981 ◽  
Vol 6 ◽  
Author(s):  
J.R. Mclaren ◽  
R.W. Davidge ◽  
I. Titchell ◽  
K. Sincock ◽  
A. Bromley
Keyword(s):  
Thermal Expansion ◽  
Grain Boundary ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Crack Density ◽  
Granitic Rocks ◽  
Multiphase Materials ◽  
Thermal Expansion Behaviour ◽  
Waste Repositories ◽  
Expansion Behaviour

ABSTRACTHeating to temperatures up to 500°C, gives a reduction in Young's modulus and increase in permeability of granitic rocks and it is likely that a major reason is grain boundary cracking. The cracking of grain boundary facets in polycrystalline multiphase materials showing anisotropic thermal expansion behaviour is controlled by several microstructural factors in addition to the intrinsic thermal and elastic properties. Of specific interest are the relative orientations of the two grains meeting at the facet, and the size of the facet; these factors thus introduce two statistical aspects to the problem and these are introduced to give quantitative data on crack density versus temperature. The theory is compared with experimental measurements of Young's modulus and permeability for various rocks as a function of temperature. There is good qualitative agreement, and the additional (mainly microstructural) data required for a quantitative comparison are defined.

Is it necessary to calculate Young’s modulus in AFM nanoindentation experiments regarding biological samples?

2020 ◽  
Vol 12 ◽  
Author(s):  
S.V. Kontomaris ◽  
A. Malamou ◽  
A. Stylianou
Keyword(s):  
Young’S Modulus ◽  
Biological Samples ◽  
Young's Modulus ◽  
Reference Sample ◽  
Nonlinear Behavior ◽  
Accurate Method ◽  
Accurate Solution ◽  
Hertz Model ◽  
Work Done

Background: The determination of the mechanical properties of biological samples using Atomic Force Microscopy (AFM) at the nanoscale is usually performed using basic models arising from the contact mechanics theory. In particular, the Hertz model is the most frequently used theoretical tool for data processing. However, the Hertz model requires several assumptions such as homogeneous and isotropic samples and indenters with perfectly spherical or conical shapes. As it is widely known, none of these requirements are 100 % fulfilled for the case of indentation experiments at the nanoscale. As a result, significant errors arise in the Young’s modulus calculation. At the same time, an analytical model that could account complexities of soft biomaterials, such as nonlinear behavior, anisotropy, and heterogeneity, may be far-reaching. In addition, this hypothetical model would be ‘too difficult’ to be applied in real clinical activities since it would require very heavy workload and highly specialized personnel. Objective: In this paper a simple solution is provided to the aforementioned dead-end. A new approach is introduced in order to provide a simple and accurate method for the mechanical characterization at the nanoscale. Method: The ratio of the work done by the indenter on the sample of interest to the work done by the indenter on a reference sample is introduced as a new physical quantity that does not require homogeneous, isotropic samples or perfect indenters. Results: The proposed approach, not only provides an accurate solution from a physical perspective but also a simpler solution which does not require activities such as the determination of the cantilever’s spring constant and the dimensions of the AFM tip. Conclusion: The proposed, by this opinion paper, solution aims to provide a significant opportunity to overcome the existing limitations provided by Hertzian mechanics and apply AFM techniques in real clinical activities.

Effect of Microcrystalline Cellulose from Banana Stem Fiber on Mechanical Properties and Crystallinity of PLA Composite Films

2011 ◽  
Vol 695 ◽  
pp. 170-173 ◽  
Author(s):  
Voravadee Suchaiya ◽  
Duangdao Aht-Ong
Keyword(s):  
Tensile Strength ◽  
Young’S Modulus ◽  
Microcrystalline Cellulose ◽  
Young's Modulus ◽  
Agricultural Waste ◽  
Composite Films ◽  
Sem Image ◽  
Biocomposite Films ◽  
Twin Screw ◽  
Banana Stem

This work focused on the preparation of the biocomposite films of polylactic acid (PLA) reinforced with microcrystalline cellulose (MCC) prepared from agricultural waste, banana stem fiber, and commercial microcrystalline cellulose, Avicel PH 101. Banana stem microcrystalline cellulose (BS MCC) was prepared by three steps, delignification, bleaching, and acid hydrolysis. PLA and two types of MCC were processed using twin screw extruder and fabricated into film by a compression molding. The mechanical and crystalline behaviors of the biocomopsite films were investigated as a function of type and amount of MCC. The tensile strength and Young’s modulus of PLA composites were increased when concentration of MCC increased. Particularly, banana stem (BS MCC) can enhance tensile strength and Young’s modulus of PLA composites than the commercial MCC (Avicel PH 101) because BS MCC had better dispersion in PLA matrix than Avicel PH 101. This result was confirmed by SEM image of fractured surface of PLA composites. In addition, XRD patterns of BS MCC/PLA composites exhibited higher crystalline peak than that of Avicel PH 101/PLA composites

scholarly journals Out-of-Plane Thermal Expansion Coefficient and Biaxial Young’s Modulus of Sputtered ITO Thin Films

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 153
Author(s):  
Chuen-Lin Tien ◽  
Tsai-Wei Lin
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Young’S Modulus ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Young's Modulus ◽  
Heating Temperature ◽  
Glass Substrates ◽  
Ito Thin Films

This paper proposes a measuring apparatus and method for simultaneous determination of the thermal expansion coefficient and biaxial Young’s modulus of indium tin oxide (ITO) thin films. ITO thin films simultaneously coated on N-BK7 and S-TIM35 glass substrates were prepared by direct current (DC) magnetron sputtering deposition. The thermo-mechanical parameters of ITO thin films were investigated experimentally. Thermal stress in sputtered ITO films was evaluated by an improved Twyman–Green interferometer associated with wavelet transform at different temperatures. When the heating temperature increased from 30 °C to 100 °C, the tensile thermal stress of ITO thin films increased. The increase in substrate temperature led to the decrease of total residual stress deposited on two glass substrates. A linear relationship between the thermal stress and substrate heating temperature was found. The thermal expansion coefficient and biaxial Young’s modulus of the films were measured by the double substrate method. The results show that the out of plane thermal expansion coefficient and biaxial Young’s modulus of the ITO film were 5.81 × 10−6 °C−1 and 475 GPa.

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