scholarly journals Mechanical Properties of a Primary Cilium from the Stochastic Motions of the Cilium Tip

2018 ◽  
Author(s):  
J. Flaherty ◽  
Z. Feng ◽  
Z. Peng ◽  
Y.-N. Young ◽  
A. Resnick
Keyword(s):  
Mechanical Properties ◽  
Primary Cilium ◽  
Primary Cilia ◽  
Flexural Rigidity ◽  
Optical Trap ◽  
Body Motion ◽  
Flow Sensing ◽  
Cytoskeletal Dynamics ◽  
First Time ◽  
Optically Trapped

ABSTRACTThe stochastic tip dynamics of a primary cilium held within an optical trap is quantified by combining experimental, analytical and computational tools. Primary cilia are cellular organelles, present on most vertebrate cells, hypothesized to function as a fluid flow sensor. The mechanical properties of a cilium remain incompletely characterized. We measured the fluctuating position of an optically trapped cilium tip under untreated, Taxol-treated, and HIF-stabilized conditions. We applied analytical modeling to derive the mean-squared displacement of the trapped tip of a cilium and compared the results with experimental measurements. We provide, for the first time, evidence that the effective flexural rigidity of a ciliary axoneme is length-dependent, and longer cilia are stiffer than shorter cilia. We then provide a rational explanation for both effects. We demonstrate that the apparent length-dependent flexural rigidity can be understood by a combination of modeling axonemal microtubules orthotropic elastic shells and including (actin-driven) active stochastic basal body motion. It is hoped that our improved characterization of cilia will result in deeper understanding of the biological function of cellular flow sensing by this organelle. Our model could be profitably applied to motile cilia and our results also demonstrate the possibility of using easily observable ciliary dynamics to probe interior cytoskeletal dynamics.

scholarly journals Primary cilia have a length-dependent persistence length

2019 ◽  
Vol 19 (2) ◽  
pp. 445-460
Author(s):  
Justin Flaherty ◽  
Zhe Feng ◽  
Zhangli Peng ◽  
Y.-N. Young ◽  
Andrew Resnick
Keyword(s):  
Basal Body ◽  
Primary Cilia ◽  
Persistence Length ◽  
Body Motion ◽  
Flow Sensing ◽  
Cytoskeletal Dynamics ◽  
Anisotropic Elastic ◽  
First Time ◽  
Optically Trapped

Abstract The fluctuating position of an optically trapped cilium tip under untreated and Taxol-treated conditions was used to characterize mechanical properties of the cilium axoneme and its basal body by combining experimental, analytical, and computational tools. We provide, for the first time, evidence that the persistence length of a ciliary axoneme is length-dependent; longer cilia are stiffer than shorter cilia. We demonstrate that this apparent length dependence can be understood by a combination of modeling axonemal microtubules as anisotropic elastic shells and including actomyosin-driven stochastic basal body motion. Our results also demonstrate the possibility of using observable ciliary dynamics to probe interior cytoskeletal dynamics. It is hoped that our improved characterization of cilia will result in deeper understanding of the biological function of cellular flow sensing by this organelle.

scholarly journals Mechanical Properties of Isolated Primary Cilia Measured by Micro-tensile Test and Atomic Force Microscopy

2021 ◽  
Vol 9 ◽  
Author(s):  
Tien-Dung Do ◽  
Jimuro Katsuyoshi ◽  
Haonai Cai ◽  
Toshiro Ohashi
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Young’S Modulus ◽  
Primary Cilia ◽  
Flexural Rigidity ◽  
Young's Modulus ◽  
Optical Trap ◽  
Mechanical Stimuli ◽  
Force Microscopy ◽  
Atomic Force

Mechanotransduction is a well-known mechanism by which cells sense their surrounding mechanical environment, convert mechanical stimuli into biochemical signals, and eventually change their morphology and functions. Primary cilia are believed to be mechanosensors existing on the surface of the cell membrane and support cells to sense surrounding mechanical signals. Knowing the mechanical properties of primary cilia is essential to understand their responses, such as sensitivity to mechanical stimuli. Previous studies have so far conducted flow experiments or optical trap techniques to measure the flexural rigidity EI (E: Young’s modulus, I: second moment of inertia) of primary cilia; however, the flexural rigidity is not a material property of materials and depends on mathematical models used in the determination, leading to a discrepancy between studies. For better characterization of primary cilia mechanics, Young’s modulus should be directly and precisely measured. In this study, the tensile Young’s modulus of isolated primary cilia is, for the first time, measured by using an in-house micro-tensile tester. The different strain rates of 0.01–0.3 s−1 were applied to isolated primary cilia, which showed a strain rate–dependent Young’s modulus in the range of 69.5–240.0 kPa on average. Atomic force microscopy was also performed to measure the local Young’s modulus of primary cilia, showing the Young’s modulus within the order of tens to hundreds of kPa. This study could directly provide the global and local Young’s moduli, which will benefit better understanding of primary cilia mechanics.

Analysis and modeling of the primary cilium bending response to fluid shear

1997 ◽  
Vol 272 (1) ◽  
pp. F132-F138 ◽  
Author(s):  
E. A. Schwartz ◽  
M. L. Leonard ◽  
R. Bizios ◽  
S. S. Bowser
Keyword(s):  
Epithelial Cells ◽  
Primary Cilium ◽  
Primary Cilia ◽  
Fluid Shear Stress ◽  
Flexural Rigidity ◽  
Fluid Motion ◽  
Large Angle ◽  
Fluid Shear ◽  
Kidney Epithelial Cells

Since a nonmotile, primary (9 + 0) cilium projects from most mammalian kidney epithelial cells into the tubule lumen, where it is exposed to fluid motion, the present study examined primary cilium response to fluid shear stress. The reversible, large-angle bending of the primary cilium upon exposure to fluid shear forces (10(-11)-10(-10) N.m2 = 10(-8)-10(-7) dyn/cm) was characterized in vitro using videomicroscopic side views of PtK1 cells, and the cilium was then mathematically modeled as a cantilevered beam. The flexural rigidity of the primary cilium was calculated to be 3.1 +/- 0.8 x 10(-23) N.m2 with a corrected quadruple integration approach and 1.4-1.6 x 10(-23) N.m2 with the "heavy elastica" theory. Comparison of theoretical profiles to the experimental bending responses of cilia established the validity of the "heavy elastica" model; this model, in turn, was used to predict primary cilium bending behavior under representative conditions in the rat nephron. The results of the study are consistent with the hypothesis that primary cilia serve a mechanosensory function in kidney epithelial cells.

Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part IV: Laboratory Measurement of Mechanical Properties and Mechanical Actions of Tires Relating to Treadwear

1986 ◽  
Vol 14 (4) ◽  
pp. 264-291
Author(s):  
K. L. Oblizajek ◽  
A. G. Veith
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Contact Zone ◽  
Flexural Rigidity ◽  
Comprehensive Evaluation ◽  
Shear Stiffness ◽  
Shear Stresses ◽  
Lateral Shear ◽  
Band Bending ◽  
Tread Rubber

Abstract Treadwear is explained by specific mechanical properties and actions of tires. Rubber shear stresses in the contact zone between the tire and the road become large at large slip angles. When normal stresses are insufficient to prevent sliding at the rear of the footprint, wear occurs at a rate that depends on test severity. Two experimental approaches are described to relate treadwear to tire characteristics. The first uses transducers imbedded in a simulated road surface to obtain direct measurements of contact stresses on the loaded, freely-rolling, steered tires. The second approach is developed with the aid of a simple carcass, tread-band, tread-rubber tire model. Various tire structural configurations; characterized by carcass spring rate, edgewise flexural band stiffness, and tread rubber shear stiffness; are simulated and lateral shear stress response in the contact zone is determined. Tires featuring high band stiffness and low carcass stiffness generate lower lateral shear stress levels. Furthermore, coupling of tread-rubber stiffness and band flexural rigidity are important in determining level of shear stresses. Laboratory measurements with the described apparatus produced values of tread-band bending and carcass lateral stiffness for several tire constructions. Good correlation is shown between treadwear and a broad range of tire stiffness and test course severities.

Improving the Strength of Abrasive Wheels and Optimizing the Control over the Strength of Composite Abrasive Materials

2019 ◽  
Vol 946 ◽  
pp. 380-385
Author(s):  
Boris A. Chaplygin ◽  
Viacheslav V. Shirokov ◽  
Tat'yana A. Lisovskaya ◽  
Roman A. Lisovskiy
Keyword(s):  
Mechanical Properties ◽  
Test Results ◽  
Key Factors ◽  
Special Equipment ◽  
Material Density ◽  
Factors Affecting ◽  
Control Factors ◽  
Reinforcing Material ◽  
Special Studies ◽  
First Time

The strength of abrasive wheels is one of the key factors affecting the performance of abrasive machining. The paper discusses ways to improve the strength of abrasive wheels. The stress-state mathematical model presented herein is a generalization of the existing models. It is used herein to find for the first time that there are numerous optimal combinations of the elastic modulus and reinforcing material density, which result in the same minimum value of the objective function. It is found out that increasing the radius of the reinforcing component while also optimizing the mechanical properties of its material may increase the permissible breaking speed of the wheel several times. We herein present a regression equation and a nomogram for finding the optimal combination of control factors. Conventional methods for testing the mechanical properties of materials, which have been proven reliable for testing metals and alloys, are not as reliable for testing abrasive materials, as the test results they generate are not sufficiently stable or accurate. We therefore propose an alternative method that does not require any special equipment or special studies.

scholarly journals Mechanical and Thermoelectric Properties of Bulk AlSb Synthesized by Controlled Melting, Pulverizing and Subsequent Vacuum Hot Pressing

2019 ◽  
Vol 9 (8) ◽  
pp. 1609 ◽  
Author(s):  
A. K. M. Ashiquzzaman Shawon ◽  
Soon-Chul Ur
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compound ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Single Phase ◽  
Aluminum Antimonide ◽  
Simple Method ◽  
Group Iii ◽  
Indirect Band Gap ◽  
First Time

Aluminum antimonide is a semiconductor of the Group III-V order. With a wide indirect band gap, AlSb is one of the least discovered of this family of semiconductors. Bulk synthesis of AlSb has been reported on numerous occasions, but obtaining a single phase has always proven to be extremely difficult. This work reports a simple method for the synthesis of single-phase AlSb. Subsequently, consolidation was done into a near single-phase highly dense semiconductor in a form usable for thermoelectric applications. Further, the thermoelectric properties of this system are accounted for the first time. In addition, the mechanical properties of the intermetallic compound are briefly discussed for a possibility of further use.

Novel Baddeleyite-Based Zirconia Ceramics for Biomedical Applications

2017 ◽  
Vol 13 ◽  
pp. 9-14
Author(s):  
Alexander I. Tyurin ◽  
Andrey O. Zhigachev ◽  
Alexey V. Umrikhin ◽  
Vyacheslav V. Rodaev ◽  
Tatyana S. Pirozhkova
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tetragonal Phase ◽  
Biomedical Applications ◽  
Zirconia Ceramics ◽  
Engineering Ceramics ◽  
Synthesis Conditions ◽  
Microstructure And Mechanical Properties ◽  
First Time

For the first time nanostructured engineering ceramics were prepared from natural zirconia mineral (baddeleyite) with CaO as a tetragonal phase stabilizer. The effect of synthesis conditions on microstructure and mechanical properties of the baddeleyite-based ceramics is reported, furthermore, the effect of calcia content on hardness and fracture toughness is studied. Optimal calcia concentration and synthesis conditions are found, corresponding hardness and fracture toughness values are 10,8 GPa and 13,3 MPa×m1/2. The reported mechanical properties are comparable to those typically reported for yttria-stabilized engineering zirconia ceramics, prepared from chemically synthesized zirconia.

Minimization of the Local Residual Stress in 3D Flip Chip Structures by Optimizing the Mechanical Properties of Electroplated Materials and the Alignment Structure of TSVs and Fine Bumps

2011 ◽  
Author(s):  
Kohta Nakahira ◽  
Hironori Tago ◽  
Fumiaki Endo ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Deformation ◽  
Flip Chip ◽  
Flexural Rigidity ◽  
Three Dimensional ◽  
Strain Gauges ◽  
Copper Interconnection ◽  
Induced Stress ◽  
Alignment Structure

Since the thickness of the stacked silicon chips in 3D integration has been thinned to less than 100 μm, the local thermal deformation of the chips has increased drastically because of the decrease of the flexural rigidity of the thinned chips. The clear periodic thermal deformation and thus, the thermal residual stress distribution appears in the stacked chips due to the periodic alignment of metallic bumps, and they deteriorate the reliability of products. In this paper, the dominant structural factors of the local residual stress in a silicon chip are discussed quantitatively based on the results of a three-dimensional finite element analysis and the measurement of the local residual stress in a chip using stress sensor chips. The piezoresistive strain gauges were embedded in the sensor chips. The length of each gauge was 2 μm, and an unit cell consisted of 4 gauges with different crystallographic directions. This alignment of strain gauges enables to measure the tensor component of three-dimensional stress fields separately. Test flip chip substrates were made by silicon chip on which the area-arrayed tin/copper bumps were electroplated. The width of a bump was fixed at 200 μm, and the bump pitch was varied from 400 μm to 1000 μm. The thickness of the copper layer was about 40 μm and that of tin layer was about 10 μm. This tin layer was used for the rigid joint formation by alloying with copper interconnection formed on a stress sensing chip. The measured amplitude of the residual stress increased from about 30 MPa to 250 MPa depending on the combination of materials such as bump, underfill, and interconnections. It was confirmed that both the material constant of underfill and the alignment structure of fine bumps are the dominant factors of the local deformation and stress of a silicon chip mounted on area-arrayed metallic bumps. It was also confirmed experimentally that both the hound’s-tooth alignment between a TSV (Through Silicon Via) and a bump and control of mechanical properties of electroplated copper thin films used for the TSV and bump is indispensable in order to minimize the packaging-induced stress in the three-dimensionally mounted chips. This test chip is very effective for evaluating the packaging-process induced stress in 3D stacked chips quantitatively.

Dynamic-Mechanical Properties of Tin-Coupled SBRs

1995 ◽  
Vol 68 (2) ◽  
pp. 259-266 ◽  
Author(s):  
C. A. Sierra ◽  
C. Galán ◽  
J. M. Gómez Fatou ◽  
V. Ruíz Santa Quiteria
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Interaction Parameter ◽  
Anionic Polymerization ◽  
Dynamic Mechanical Properties ◽  
Tin Compounds ◽  
Dynamic Mechanical ◽  
Tin Content ◽  
First Time

Abstract The interaction between rubber and carbon black in compounds for road tire treads has been analyzed by using mechanical and dynamical measurements in three cured compounds based on SBRs. The rubbers were prepared in solution by anionic polymerization, and coupled with tin compounds in which the carbon-tin bond at the end of the chain may correspond to styryl or butadienyl terminations. The interaction parameter, defined by the ratio of mechanical and dynamic terms, has been used for the first time for the evaluation of the compounds. The SBRs with tin-butadienyl bonds exhibit an improved interaction with the filler, with increasing tin content.

Mechanical performance of polyester pin-reinforced foam filled honeycomb sandwich panels

2018 ◽  
Vol 25 (4) ◽  
pp. 797-805 ◽  
Author(s):  
R.S. Jayaram ◽  
V.A. Nagarajan ◽  
K.P. Vinod Kumar
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Flexural Rigidity ◽  
Sandwich Panels ◽  
Interfacial Strength ◽  
Structural Performance ◽  
Experimental Investigations ◽  
Honeycomb Sandwich ◽  
Foam Filled ◽  
Pin Reinforcement

Abstract Honeycomb sandwich panels entice continuously enhanced attention due to its excellent mechanical properties and multi-functional applications. However, the principal problem of sandwich panels is failure by face/core debond. Novel lightweight sandwich panels with hybrid core made of honeycomb, foam and through-thickness pin was developed. Reinforcing polyester pins between faces and core is an effectual way to strengthen the core and enhance the interfacial strength between the face/core to improve the structural performance of sandwich panels. To provide feasibility for pin reinforcement, honeycomb core was pre-filled with foam. Mechanical properties enhancement due to polyester pinning were investigated experimentally under flatwise compression, edgewise compression and flexural test. The experimental investigations were carried out for both “foam filled honeycomb sandwich panels” (FHS) and “polyester pin-reinforced foam filled honeycomb sandwich panels” (PFHS). The results show that polyester pin reinforcement in foam filled honeycomb sandwich panel enhanced the flatwise, edgewise compression and flexural properties considerably. Moreover, increasing the pin diameter has a larger effect on the flexural rigidity of PFHS panels. PFHS panels have inconsequential increase in weight but appreciably improved their structural performance.

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