scholarly journals Imaging viscoelastic properties of live cells by AFM: power-law rheology on the nanoscale

Soft Matter ◽  
2015 ◽  
Vol 11 (23) ◽  
pp. 4584-4591 ◽  
Author(s):  
Fabian M. Hecht ◽  
Johannes Rheinlaender ◽  
Nicolas Schierbaum ◽  
Wolfgang H. Goldmann ◽  
Ben Fabry ◽  
...  
Keyword(s):  
Power Law ◽  
Viscoelastic Properties ◽  
Live Cells

scholarly journals On the time-temperature equivalency in green wood: Characterisation of viscoelastic properties in longitudinal direction

Holzforschung ◽  
2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Jana Dlouhá ◽  
Bruno Clair ◽  
Olivier Arnould ◽  
Petr Horáček ◽  
Joseph Gril
Keyword(s):  
Power Law ◽  
Viscoelastic Properties ◽  
Creep Behaviour ◽  
Longitudinal Direction ◽  
Temperature Dependency ◽  
Arrhenius Law ◽  
Degree Polynomial ◽  
Creep Tests ◽  
Softening Effect ◽  
Green Wood

Abstract Aiming at modelling tree mechanics, viscoelastic properties of green wood along fibres was investigated through a sequence of creep tests in the temperature range of 30°C–70°C. The apparent validity of time-temperature equivalency was questioned by discrepancies evidenced in the approximated complex plane (ACP). This paradox was solved by assuming that the temperature not only accelerates the viscoelastic processes but also slightly increases their intensity. This softening effect of the temperature on the compliance was described by a 2nd degree polynomial. Time-temperature dependency fitted very well to the Arrhenius law up to 60°C. Based on the ACP, the power law was proposed for modelling creep behaviour in green wood. The method was successfully used for all specimens investigated.

Statistics of Single Cell Mechanics Investigated by Atomic Force Microscopy

2010 ◽  
Vol 1261 ◽  
Author(s):  
Shinichiro Hiratsuka ◽  
Yusuke Mizutani ◽  
PingGen Cai ◽  
Masahiko Tsuchiya ◽  
Hiroshi Tokumoto ◽  
...  
Keyword(s):  
Single Cell ◽  
Power Law ◽  
Force Measurement ◽  
Live Cells ◽  
Structural Damping ◽  
Force Microscopy ◽  
Atomic Force ◽  
Storage And Loss Moduli ◽  
Power Law Function ◽  
Damping Model

AbstractWe have developed the atomic force microsocpy (AFM) to measure the complex shear modulus, G*, of a large number of cells. In the AFM technique, live cells were arranged in a micro-fabricated glass substrate under the physiological conditions, and the AFM force measurement was examined in many different cells automatically. The results shown in the previous studies revealed that the frequency-dependent G* was well fitted to the so-called structural damping model, which consists of a single power-law function with a Newtonian viscous effect. However, the detail relationship has not been understood. The aim of this study was to verify the relationship between the storage and loss moduli. As results, we found that the relation between the hysteresivity (the ratio of the storage and loss moduli) and the power-law exponent was in good agreement with the structural damping model, and the result was the same as that observed in magnetic twisting cytometry (MTC), in which cells were cultured on flat substrates. This result indicated that the AFM technique presented here becomes a useful technique for precisely measuring the statistical behavior of single cell rheology.

scholarly journals Collagen networks determine viscoelastic properties of connective tissues yet do not hinder diffusion of the aqueous solvent

Soft Matter ◽  
2019 ◽  
Vol 15 (14) ◽  
pp. 3055-3064 ◽  
Author(s):  
Frank Sauer ◽  
Linda Oswald ◽  
Angela Ariza de Schellenberger ◽  
Heiko Tzschätzsch ◽  
Felix Schrank ◽  
...  
Keyword(s):  
Power Law ◽  
Viscoelastic Properties ◽  
Collagen Gels ◽  
Connective Tissues ◽  
Aqueous Solvent

Novel tabletop MRE reveals loss of viscoelastic power law behavior in structurally unchanged collagen gels after intrafibrillar crosslinking.

scholarly journals Differences in Viscoelasticity of Ophthalmic Polymer Solution after Sterilization

2020 ◽  
Vol 17 (7) ◽  
pp. 686-697
Author(s):  
Yotsanan WEERAPOL ◽  
Pornsak SRIAMORNSAK
Keyword(s):  
Polymer Solution ◽  
Power Law ◽  
Viscoelastic Properties ◽  
Membrane Filtration ◽  
Loss Modulus ◽  
Methyl Cellulose ◽  
Ophthalmic Solution ◽  
Solution Viscosity ◽  
Steam Sterilization ◽  
Power Law Index

Polymer solution has been used for increasing viscosity of ophthalmic solution in order to prolong the retention of active drug in the eye. The ophthalmic solution must be sterilized, which may affect the rheology properties of viscosity-inducing polymers. The aim of this study was to investigate the effect of sterilization treatment on viscosity-inducing agents (i.e., poloxamer, polyvinyl alcohol; (PVA), methyl cellulose (MC), polyvinylpyrrolidone (PVP) and carbomer). The effect of membrane filtration and steam sterilization or autoclaving (121 °C, 15 Ib/inch2, 15 min) were determined. A rheometer was used to investigate the viscosity and viscoelastic properties between treated and untreated polymer solutions. The power law model, consistency index (k), and power law index (n) of polymer solution viscosity were compared. For viscoelastic properties, storage modulus and loss modulus were examined. The results demonstrated that, viscosity of carbomer and MC solution (1 and 2 %) were changed after steam sterilization. No difference in viscosity was observed for PVP, PVA and poloxamer solution, between untreated and treated samples. The storage and loss moduli of PVA solution after autoclaving were not different when comparing with the untreated polymer solution. From this study, it could be concluded that the sterilization treatment influenced the viscosity behavior and viscoelastic properties of polymer solution used as viscosity-inducing agent in ophthalmic solution. Therefore, the selection of polymer and sterilization method should be carefully considered.

Analysis of power law assumptions for short-period comets and Kuiper bodies

1999 ◽  
Vol 173 ◽  
pp. 289-293 ◽  
Author(s):  
J.R. Donnison ◽  
L.I. Pettit
Keyword(s):  
Power Law ◽  
Pareto Distribution ◽  
Limited Data ◽  
Short Period ◽  
Probability Plots ◽  
Exponential Probability

AbstractA Pareto distribution was used to model the magnitude data for short-period comets up to 1988. It was found using exponential probability plots that the brightness did not vary with period and that the cut-off point previously adopted can be supported statistically. Examination of the diameters of Trans-Neptunian bodies showed that a power law does not adequately fit the limited data available.

4-dimensional, high-resolution imaging of living cells

1992 ◽  
Vol 50 (1) ◽  
pp. 416-417
Author(s):  
Shinya Inoué
Keyword(s):  
Light Microscope ◽  
Living Cells ◽  
Live Cells ◽  
Video Tape ◽  
Active Living ◽  
High Resolution Imaging ◽  
3 Dimensional ◽  
Dynamic Architecture ◽  
Resolution Imaging ◽  
Disk Memory

This paper reports progress of our effort to rapidly capture, and display in time-lapsed mode, the 3-dimensional dynamic architecture of active living cells and developing embryos at the highest resolution of the light microscope. Our approach entails: (A) real-time video tape recording of through-focal, ultrathin optical sections of live cells at the highest resolution of the light microscope; (B) repeat of A at time-lapsed intervals; (C) once each time-lapsed interval, an image at home focus is recorded onto Optical Disk Memory Recorder (OMDR); (D) periods of interest are selected using the OMDR and video tape records; (E) selected stacks of optical sections are converted into plane projections representing different view angles (±4 degrees for stereo view, additional angles when revolving stereos are desired); (F) analysis using A - D.

Multi-mode light microscopy of microtubule assembly dynamics and chromosome movement in vivo and In vitro

1996 ◽  
Vol 54 ◽  
pp. 730-731
Author(s):  
E. D. Salmon ◽  
J. C. Waters ◽  
C. Waterman-Storer
Keyword(s):  
Imaging System ◽  
Ccd Camera ◽  
Transmitted Light ◽  
Microtubule Assembly ◽  
Live Cells ◽  
Optical Efficiency ◽  
Multiple Band ◽  
Multi Mode

We have developed a multi-mode digital imaging system which acquires images with a cooled CCD camera (Figure 1). A multiple band pass dichromatic mirror and robotically controlled filter wheels provide wavelength selection for epi-fluorescence. Shutters select illumination either by epi-fluorescence or by transmitted light for phase contrast or DIC. Many of our experiments involve investigations of spindle assembly dynamics and chromosome movements in live cells or unfixed reconstituted preparations in vitro in which photodamage and phototoxicity are major concerns. As a consequence, a major factor in the design was optical efficiency: achieving the highest image quality with the least number of illumination photons. This principle applies to both epi-fluorescence and transmitted light imaging modes. In living cells and extracts, microtubules are visualized using X-rhodamine labeled tubulin. Photoactivation of C2CF-fluorescein labeled tubulin is used to locally mark microtubules in studies of microtubule dynamics and translocation. Chromosomes are labeled with DAPI or Hoechst DNA intercalating dyes.

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