Post Tagged with: "Nature"

NanoPropulsion


Stephen J. Ebbens

Jonathan Howse

The current state of the art in nanopropulsion devices was recently reviewed by Ebbens and Howse in an article last Friday.[SoftMatter] A short summary of the nano- systems is presented below with video action shots when I could find them.

The Whitesides

Catalyst: Pt
Fuel: H2O2
Propulsion: Bubble propulsion
Terrain: Aqueous meniscus
Max Speed: 2 cm/s
Mitch’s Name: The Karl Benz (since it was the first)
Article: Autonomous Movement and Self-Assembly

The Sen-Mallouk-Crespi

Catalyst: Pt
Fuel: H2O2
Propulsion: Self electrophoresis/Interfacial tension
Terrain: Settled near boundary in aqueous solution
Max Speed: 6.6 um/s
Mitch’s Names: The Ford Mustang of nanopropulsion. (It is a hot rod, get it?)
Article: Catalytic Nanomotors: Autonomous Movement of Striped Nanorods

The Jones-Golestanian

Catalyst: Pt
Fuel: H2O2
Propulsion: Pure self diffusiophoresis
Terrain: Free aqueous solution
Max Speed: 3um/s
Mitch’s Name: The Volkswagen Beetle
Article: Self-Motile Colloidal Particles: From Directed Propulsion to Random Walk

The Mano-Heller

Catalyst: Glucose oxidase and Biliruben oxidase
Fuel: Glucose
Propulsion: Self electrophoresis
Terrain: Aqueous meniscus
Max Speed: 1 cm/s
Mitch’s Name: The Komatsu Truck (because it is huge)
Article: Bioelectrochemical Propulsion

The Feringa

Catalyst: Synthetic catalse
Fuel: H2O2
Propulsion: Bubble/interfacial
Terrain: Acetonitrile solution
Max Speed: 35 um/s
Mitch’s Name: The F150 (has some exhaust issues)
Article: Catalytic molecular motors: fuelling autonomous movement by a surface bound synthetic manganese catalase

The Sen-Mallouk

Catalyst: Pt (CNT) (+cathodic reactions at Au)
Fuel: H2O2/N2H4
Propulsion: Self electrophoresis
Terrain: Settled near boundary in aqueous solution
Max Speed: 200 um/s
Mitch’s Names: The Ford Mustang GT (has more kick than the regular version)
Article: Bipolar Electrochemical Mechanism for the Propulsion of Catalytic Nanomotors in Hydrogen Peroxide Solutions

The Feringa v2

Catalyst: Glucose oxidase and catalse
Fuel: Glucose
Propulsion: Local oxygen bubble formation
Terrain: Free aqueous buffer solution
Max Speed: 0.2–0.8 um/s
Mitch’s Name: The Chevrolet Nova (more hot rod action)
Article: Autonomous propulsion of carbon nanotubes powered by a multienzyme ensemble

The Gibbs-Zhao

Catalyst: Pt
Fuel: H2O2
Propulsion: Bubble release mechanism
Terrain: Aqueous solution
Max Speed: 6 um/s
Mitch’s Name: The Rover
Article: Autonomously motile catalytic nanomotors by bubble propulsion

The Bibette

Engine: External magnetic field
Propulsion: Flagella
Terrain: Aqueous solution
Max Speed: unknown
Mitch’s name: The BMW Mini E (because there is no such thing as a magnetic car)
Article: Microscopic artificial swimmers

The Sagués

Engine: External magnetic field
Propulsion: Doublet rotation coupling with boundary interactions
Terrain: Settled near boundary in aqueous solution
Max Speed: 3.2 um/s
Mitch’s Name: The Smart ED
Article: Magnetically Actuated Colloidal Microswimmers

The Fischer

Engine: External magnetic field
Propulsion: Propeller drive
Terrain: Aqueous solution
Max Speed: 40 um/s
Mitch’s Name:
Article: Controlled Propulsion of Artificial Magnetic Nanostructured Propellers

The Najafi-Golestanian

Engine: Conformation changes in linking units
Propulsion: Time irreversible translations
Terrain: Free solution
Max Speed: ?
Mitch’s Name: The Eternal Concept Car
Article: Propulsion at low Reynolds number



Some devices that were not included by the authors of the review article, but should definitely be included in any list like this are below:

The Gracias

Engine: External magnetic field
Propulsion: Brute Force
Terrain: Aqueous solution
Max Speed: ?
Mitch’s Name: The Truck Cranes
Article: Tetherless thermobiochemically actuated microgrippers

Tetherless Microgrippers Grabs Tissue SampleWatch today’s top amazing videos here

The Nelson

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Engine: External electromagnetic fields
Propulsion: Flagella
Terrain: ?
Max Speed: 18 um/s
Mitch’s Name: The Tesla Roadster (simply awesome)
Article: Characterizing the Swimming Properties of Artificial Bacterial Flagella

Artificial SpermWatch more funny videos here




Link to Review Article: In pursuit of propulsion at the nanoscale

Mitch

By January 16, 2010 6 comments materials chemistry

Long-term Experiments

I recently read this Nature article, where is described what is probably one of the longest experiments ever to be conducted. A population of E. coli was kept for 20 years (!) in a nutrient solution (low on glucose), and samples were taken and deep-frozen after 2000, 5000, 10000, 15000, 20000 and 40000 generations. The authors sequenced the genome of the sample bacteria to investigate the rate of mutations.

Up to generation 20K, the number of mutations grew steadily to a total of 45. The adaptation to the environment, however, only increased strongly in the beginning. It was concluded that the most beneficial mutations were the first to occur. After generation 20K, a change in the mutT gene caused a rapid increase in the mutation rate to result in 653 mutation at generation 40K, but with a neutral signature, i.e. no further adaptation.

What I find most fascinating about this extreme long-term experiment is the confidence of the researchers that it would be possible to analyze the genes at a later point; this was not at all self-evident in the late ’80s! In addition, some work had to be done each day, for twenty years. What if the power had failed for a week or so? Of course, this unique opportunity to watch evolution as it happens is very intriguing.

An experiment that took even longer was awarded this year’s Ig Nobel Prize in medicine: Donald L. Unger of Thousand Oaks, CA, cracked the knuckles of his left hand, but not his right hand, every day for 50 years to see if knuckle-cracking leads to arthritis. After this time, both hands were fine, so he concluded: “While a larger group would be necessary to confirm this result, this preliminary investigation suggests a lack of correlation between knuckle cracking and the development of arthritis of the fingers.” Apparently, the experiment must be repeated.

By October 23, 2009 2 comments Uncategorized

Joking in a Nature journal?

Was reading this earlier this evening on the hobby science forum Sciencemadness.org –it’s amusing.

Read the letter carefully.

Well, let’s hope this is a joke.

By July 8, 2009 5 comments fun, Uncategorized

Condensed Print Format

My boss has pointed out this piece of news covered by C&EN. Apparently, starting from July, all ACS journals will be printed in a “rotated and condensed” format, that is two pages on one printed page in landscape format. This is an effort to reduce printing and distribution costs.

In my opinion, this change is just one further step towards purely electronic journals that are not printed at all. I think this will deeply affect the way we present our data and how we look at formatting. Preparing a manuscript in a way meant for printing is different from one which will never appear in print. Some may welcome this change because it saves paper, others will probably miss the possibility of flicking through a new issue of JACS. Although I rarely go to the library to pick up a printed journal, I admit to reading printouts very often (see this post).

Update: Apparently, in 2010 the print versions will stop completely, with the exception of JACS, Acc. Chem. Res. and Chem. Rev. See also Nature News.

By June 19, 2009 8 comments opinion