Rate Acceleration of Light-Driven Rotary Molecular Motors

2007 ◽  
Vol 17 (5) ◽  
pp. 718-729 ◽  
Author(s):  
M. M. Pollard ◽  
M. Klok ◽  
D. Pijper ◽  
B. L. Feringa
Author(s):  
Tim Oliver ◽  
Michelle Leonard ◽  
Juliet Lee ◽  
Akira Ishihara ◽  
Ken Jacobson

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.


Author(s):  
Kevin Wise ◽  
Hyo Jung Kim ◽  
Jeesum Kim

A mixed-design experiment was conducted to explore differences between searching and surfing on cognitive and emotional responses to online news. Ninety-two participants read three unpleasant news stories from a website. Half of the participants acquired their stories by searching, meaning they had a previous information need in mind. The other half of the participants acquired their stories by surfing, with no previous information need in mind. Heart rate, skin conductance, and corrugator activation were collected as measures of resource allocation, motivational activation, and unpleasantness, respectively, while participants read each story. Self-report valence and recognition accuracy were also measured. Stories acquired by searching elicited greater heart rate acceleration, skin conductance level, and corrugator activation during reading. These stories were rated as more unpleasant, and their details were recognized more accurately than similar stories that were acquired by surfing. Implications of these results for understanding how people process online media are discussed.


2016 ◽  
Vol 32 (4) ◽  
pp. 60-67
Author(s):  
A. N. MOROZOV ◽  
Z. V. ZAKHAROV ◽  
R. A. KOCHELABOV ◽  
D. V. TYUPA ◽  
A. V. ISERKAPOV ◽  
...  

2019 ◽  
Vol 15 ◽  
pp. 963-970 ◽  
Author(s):  
Sora Park ◽  
Jeung Gon Kim

Mechanochemical polymerization is a rapidly growing area and a number of polymeric materials can now be obtained through green mechanochemical synthesis. In addition to the general merits of mechanochemistry, such as being solvent-free and resulting in high conversions, we herein explore rate acceleration under ball-milling conditions while the conventional solution-state synthesis suffer from low reactivity. The solvent-free mechanochemical polymerization of trimethylene carbonate using the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) are examined herein. The polymerizations under ball-milling conditions exhibited significant rate enhancements compared to polymerizations in solution. A number of milling parameters were evaluated for the ball-milling polymerization. Temperature increases due to ball collisions and exothermic energy output did not affect the polymerization rate significantly and the initial mixing speed was important for chain-length control. Liquid-assisted grinding was applied for the synthesis of high molecular weight polymers, but it failed to protect the polymer chain from mechanical degradation.


2007 ◽  
Vol 47 (supplement) ◽  
pp. S248
Author(s):  
Takuji Mashimo ◽  
Tomoyuki Yoshino ◽  
Shin-Ichi Aizawa

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