April 5, 2016
by Danilo Roccatano
Ronen Zangi and Danilo Roccatano
Nano Lett. 2016, DOI: 10.1021/acs.nanolett.6b00460
Structural order emerging in the liquid state necessitates a critical degree of anisotropy of the molecules. For example, liquid crystals and Langmuir monolayers require rod/disc-shaped and long chain amphiphilic molecules, respectively, to break the isotropic symmetry of liquids. In this paper, we present results from molecular dynamics simulations demonstrating that in two-dimensional liquids, a significantly smaller degree of anisotropy is sufficient to allow structural organization. In fact, the condensed phase of the smallest amphiphilic molecule, methanol, confined between two or adsorbed on, graphene sheets form a monolayer characterized by long chains of molecules. Intra-chain interactions are dominated by hydrogen bonds, whereas inter-chain interactions are dispersive. Upon a decrease in density toward a gas-like state, these strings are transformed into rings. The two-dimensional liquid phase of methanol undergoes another transition upon cooling; in this case, the order-disorder transition is characterized by a low-temperature phase in which the hydrogen bond dipoles of neighboring strings adopt anti-parallel orientation.
December 16, 2015
by Danilo Roccatano
Exploring the Molecular Machines within: a Fantastic Voyage
Lincoln School of Mathematics and Physics
Wednesday 16th December 2015
at 3.30 pm
EMMTEC Lecture Theatre, Brayford Pool Campus, University of Lincoln
To see a World in a Grain of Sand
And a Heaven in a Wild Flower,
Hold Infinity in the palm of your hand
And Eternity in an hour.
― William Blake, Auguries of Innocence
Nature is a great source of inspiration and emulation for scientist and engineering, and the continuous advance in the knowledge of the complex machinery of life is producing profound impacts in the modern societies. Life, in the form that we know, definitively exploited what we now call “nanotechnology” to emerge. Living cells are crowded of fascinating molecular machines with a large variety of functions not yet completely explored. Nature as a blind and patient engineer builds these machines without a blueprint but using the evolution. However, in the last 50 years, thanks to the continuous accumulation of knowledge, we have also learnt how to produce new nanosized engineering marvels.
The story plot of the 1966 SF movie A fantastic voyage, popularized with the novel written by the polymath science fiction writer Isaac Asimov, is based on the exploration of the human body with a cell sized submarine. In this talk, we will take a next step in this fantastic voyage to explore the nuts and bolts of our cell. We will use as submarine powerful computers and our imagination. In this voyage, we will discover that machines similar to those used in our day-life experience are within us and their functions is nowadays studied using the same basic physical laws discovered 350 years ago by the universal genius Isaac Newton. Therefore, the same principles that describe the motion of stars in our galaxy is helping us to unravel the complex machinery of life.