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Opening a can of worms

10 October 2014 - Biochemical

molecular dynamics plasma membrane.PNGThe image of the week is the result of a molecular dynamics simulation of a mammalian plasma membrane (DOI). It looks like a can of worms has opened but the piece of cell wall depicted (a bilayer) consists of a complex mixture of 63 different worm-like lipids (phosphatidylcholines, sphingomyelin and gangliosides for the inside and hosphatidylethanolamine and phosphatidylserine for the outside) with additional cholesterol and water thrown in. This process is called computational microscopy.

The details: simulations were performed using MARTINI and using a tool called INSANE (INSert membrANE), around half a million particles (lipids, water molecules and counter ions) were crammed into a box measuring 70 by 70 by 11 nm and monitored for 40 microseconds. Initially all players are distributed randomly but phase-separation takes place instantly with cholesterol congregating and also aliphatic lipid tails in general. The gangliosides were also found to form clusters.

The simulation reveals how cholesterol-rich regions flip-flop between the in- and outside. In the accompanying video these regions are like waves in an ocean. Not able to find: the amount of time the computations took, hours?, days?, weeks?. The 40 microseconds were not enough for everything to equilibrate. Hence the curiosity.

Meanwhile in the Whitesides lab (V)

04 October 2014 - Nobel Prize predictions

Meanwhile in the Whitesides lab. This blog continues to cover George Whitesides in the run up to the Nobel Prize in Chemistry 2014 announcement. See earlier episodes I, II, III and IV. This year we have already been covering a new use of the Maglev here but the big breakthrough this year must have been the inventive use of bubble wrap in analytical chemistry (DOI). The publication describing it all attracted some media attention for example from NPR and newscientist. Basically, bubble wrap can be used as a cheap replacement for essay plates in places with poor medical infrastructure.

What else is new? Click-e-Bricks (DOI, Newscientist) are the next evolutionary step in soft-robots. The robots are built up from Lego pieces and can do amazing stuff. See vid below.
And how to move a ball on a flat surface? Many ways exists but in one of them the surface is covered with pneumatic pins (think pinball machine) that are operated by a Braille display (DOI).