BaHigh-force magnetic tweezers with force feedback for biological applications

2007 ◽  
Vol 78 (11) ◽  
pp. 114301 ◽  
Author(s):  
Philip Kollmannsberger ◽  
Ben Fabry
Keyword(s):  
Force Feedback ◽  
Magnetic Tweezers ◽  
Biological Applications

scholarly journals High-force magnetic tweezers with hysteresis-free force feedback

2019 ◽  
Author(s):  
D. Kah ◽  
C. Dürrbeck ◽  
W. Schneider ◽  
B. Fabry ◽  
R. C. Gerum
Keyword(s):  
Force Feedback ◽  
Magnetic Hysteresis ◽  
Iron Alloy ◽  
Magnetic Tweezers ◽  
Core Material ◽  
Magnetic Field Measurement ◽  
Exponential Relationship ◽  
Plastic Properties ◽  
Magnetic Tweezer ◽  
Elastic And Plastic Deformations

ABSTRACTMagnetic tweezers based on solenoids with iron alloy cores are widely used to apply large forces (~100 nN) onto micron-sized (~5 μm) superparamagnetic particles for mechanical manipulation or microrheological measurements at the cellular and molecular level. The precision of magnetic tweezers, however, is limited by the magnetic hysteresis of the core material, especially for time-varying force protocols. Here, we eliminate magnetic hysteresis by a feedback control of the magnetic induction, which we measure with a Hall sensor mounted to the distal end of the solenoid core. We find that the generated force depends on the induction according to a power-law relationship, and on the bead-tip distance according to a stretched exponential relationship. Together, both relationships allow for an accurate force calibration and precise force feedback with only 3 calibration parameters. We apply our method to measure the force-dependence of the viscoelastic and plastic properties of fibroblasts using a protocol with stepwise increasing and decreasing forces. We find that soft cells show an increasing stiffness but decreasing plasticity at higher forces, indicating a pronounced stress stiffening of the cytoskeleton. By contrast, stiff cells show no stress stiffening but an increasing plasticity at higher forces. These findings indicate profound differences between soft and stiff cells regarding their protection mechanisms against external mechanical stress. In summary, our method increases the precision, simplifies the handling and extends the applicability of magnetic tweezers.SIGNIFICANCEMagnetic tweezers are widely used, versatile tools to investigate the mechanical behavior of cells or to measure the strength of receptor-ligand bonds. A limitation of existing high-force magnetic tweezer setups, however, is caused by the magnetic hysteresis of the tweezer core material. This magnetic hysteresis requires that the tweezer core must be de-magnetized (de-Gaussed) prior to each measurement, and that flexible force protocols with decreasing forces are not possible. We describe how these limitations can be overcome with a force feedback though direct magnetic field measurement. We demonstrate the applicability of our setup by investigating the visco-elastic and plastic deformations of fibroblasts to forces of different amplitudes.

scholarly journals High-Force Magnetic Tweezers with Hysteresis-Free Force Feedback

2020 ◽  
Vol 119 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Delf Kah ◽  
Christopher Dürrbeck ◽  
Werner Schneider ◽  
Ben Fabry ◽  
Richard Carl Gerum
Keyword(s):  
Force Feedback ◽  
Magnetic Tweezers

How SIMS microscopy can be used in medicine

1992 ◽  
Vol 50 (2) ◽  
pp. 1602-1603
Author(s):  
Philippe Fragu
Keyword(s):  
Mass Spectrometry ◽  
Biomedical Applications ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Elements ◽  
Biological Applications ◽  
The Past ◽  
Potential Source ◽  
Secondary Ion ◽  
Chemical Integrity ◽  
Scientific Endeavour

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.

Bilateral Force Feedback Control for a Vehicle-Type Tele-Mobility System

2013 ◽  
Vol 133 (8) ◽  
pp. 795-803
Author(s):  
Kazuki Nagase ◽  
Shutaro Yorozu ◽  
Takahiro Kosugi ◽  
Yuki Yokokura ◽  
Seiichiro Katsura
Keyword(s):  
Feedback Control ◽  
Force Feedback ◽  
Vehicle Type ◽  
Mobility System

Preparation of Graphene Quantum Dots and Their Biological Applications

2016 ◽  
Vol 31 (4) ◽  
pp. 337 ◽  
Author(s):  
SUN Xiao-Dan ◽  
LIU Zhong-Qun ◽  
YAN Hao
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Biological Applications

Hidden Markov Processes

2014 ◽  
Author(s):  
M. Vidyasagar
Keyword(s):  
Hidden Markov Models ◽  
Markov Processes ◽  
Viterbi Algorithm ◽  
Markov Models ◽  
Hidden Markov ◽  
Local Alignment ◽  
Biological Applications ◽  
Standard Material ◽  
Hidden Markov Processes ◽  
Genomics And Proteomics

This book explores important aspects of Markov and hidden Markov processes and the applications of these ideas to various problems in computational biology. It starts from first principles, so that no previous knowledge of probability is necessary. However, the work is rigorous and mathematical, making it useful to engineers and mathematicians, even those not interested in biological applications. A range of exercises is provided, including drills to familiarize the reader with concepts and more advanced problems that require deep thinking about the theory. Biological applications are taken from post-genomic biology, especially genomics and proteomics. The topics examined include standard material such as the Perron–Frobenius theorem, transient and recurrent states, hitting probabilities and hitting times, maximum likelihood estimation, the Viterbi algorithm, and the Baum–Welch algorithm. The book contains discussions of extremely useful topics not usually seen at the basic level, such as ergodicity of Markov processes, Markov Chain Monte Carlo (MCMC), information theory, and large deviation theory for both i.i.d and Markov processes. It also presents state-of-the-art realization theory for hidden Markov models. Among biological applications, it offers an in-depth look at the BLAST (Basic Local Alignment Search Technique) algorithm, including a comprehensive explanation of the underlying theory. Other applications such as profile hidden Markov models are also explored.

DAYA TAHAN ROTAN YANG DIAWETKAN DENGAN CUKA KAYU GALAM TERHADAP SERANGAN BUBUK Dinoderus minutus Farb.

2010 ◽  
Vol 2 (2) ◽  
pp. 8
Author(s):  
Evy Setiawati
Keyword(s):  
Force Feedback ◽  
Test Results ◽  
Dry Powder ◽  
Degree Of Protection ◽  
Wood Vinegar ◽  
Dinoderus Minutus ◽  
Test Parameters ◽  
Feedback Method ◽  
Reduction Percentage ◽  
Insect Attack

Rattan on frequently attacked by the powder post beetle (Tellu, 2001). The prevention of dry powder attacks is done by preservation. The increasing resistant of rattan from insect attack can be done by an environmentally friendly preservative, the Galam wood vinegar. This research  aims to determine the most effective concentration of preservative that shows the lowest attacks level of D. Farb minutus powder. The rattan used is green rattan (Calamus sp.) The concentration of preservative that are used:10%, 40%, 70% and 100%. The testing of dry powder attack  used force feedback method. The effectiveness test parameters of wood vinegar to dry powder attacks  included degree of protection Dinoderus minutus Farb. powder,  reduction percentage of rattan weight and the mortality of dry powder Dinoderus sp for toxicological testing of wood vinegar. The test results showed that the degree of protection powder in rattan growing along with the increased concentration of preservatives. The higher the concentration of  wood vinegar, the smaller the reduction of rattan weight and the higher the mortality rate of dry powder. Keywords: resistant of rattan, wood vinegar, Dinoderus minutus.

A REVIEW ON RECENT ADVANCES IN CHEMISTRY, SYNTHESIS AND BIOLOGICAL APPLICATIONS OF ISATIN DERIVATIVES

2018 ◽  
pp. 16-22
Author(s):  
Shukla PK ◽  
Singh MP ◽  
Patel R
Keyword(s):  
Heterocyclic Compounds ◽  
Biologically Active ◽  
Biological Applications ◽  
Plant Origin ◽  
Recent Past ◽  
Pharmacological Activities ◽  
Naturally Occurring ◽  
Recent Advances ◽  
Biological Aspects ◽  
Isatin Derivatives

Indole and its derivatives have engaged a unique place in the chemistry of nitrogen heterocyclic compounds. The recognition of the plant growthhormone, heteroauxin, the significant amino acids, tryptamine & tryptophan and anti-inflammatory drug, indomethacine are the imperativederivatives of indole which have added stimulus to this review work. Isatin (1H-indole-2,3-dione), an indole derivative of plant origin. Althoughit is a naturally occurring compound, but was synthesized by Erdmann and Laurent in 1840 before it was found in nature. Isatin is a versatileprecursor for many biologically active molecules and its diversified nature makes it a versatile substrate for further modifications. It is concernedin many pharmacological activities like anti-malarial, antiviral, anti-allergic, antimicrobial etc; isatin and its derivatives have been also found todemonstrate promising outcomes against various cancer cell lines. This review provides a brief overview on the recent advances and futureperspectives on chemistry and biological aspects of isatin and its derivatives reported in the recent past.

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