Nav: Home

How water can split into two liquids below zero

January 25, 2017

Did you know that water can still remain liquid below zero degrees Celsius? It is called supercooled water and is present in refrigerators. At even smaller temperatures, supercooled water could exist as a cocktail of two distinct liquids. Unfortunately, the presence of ice often prevents us from observing this phenomenon. So physicists had the idea of replicating the tetrahedral shape of water molecules -- using DNA as a scaffold to create tetrahedral molecules -- and thus removing the interference of ice formation. This approach allowed Simone Ciarella from the University of Rome, Italy, and his colleagues to confirm that, in theory, a dual liquid phase is possible in sub-zero water and any other liquids made of tetrahedral molecules. These results have been published in EPJ E. It is a great tale of how the underlying microscopic shape determines the overall macroscopic form.

The DNA origami technique is a kind of nanotech version of playing with Legos, assembling building blocks to create shapes at will. However, it is rather difficult to do it experimentally. The authors instead opted to use simulation to test how tetrahedral molecules -- where the arms of the tetrahedron are composed of six hard cylinders -- stack up and evolve over time.

The authors confirmed previously published ideas suggesting that it is the structure of the monomers and their network which makes it theoretically possible to have a dual liquid phase: one with high-density and one with low-density liquid. This is because the resulting lattice is sufficiently empty to allow for partial interpenetration of molecules. And it is sufficiently flexible to avoid crystallisation into ice, at least on the numerical time scale used in the study.

Then, Ciarella and his colleagues studied the tetrahedral molecules themselves with a recently introduced technique, called Successive Umbrella Sampling, to calculate information related to thermodynamics.
Reference: Towards the observation of a liquid-liquid phase transition in patchy origami tetrahedra: a numerical study. S. Ciarella, O. Gang, and F. Sciortino (2016), Eur. Phys. J. E 39: 131, DOI 10.1140/epje/i2016-16131-5


Related Dna Articles:

A new spin on DNA
For decades, researchers have chased ways to study biological machines.
From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.
Self-healing DNA nanostructures
DNA assembled into nanostructures such as tubes and origami-inspired shapes could someday find applications ranging from DNA computers to nanomedicine.
DNA design that anyone can do
Researchers at MIT and Arizona State University have designed a computer program that allows users to translate any free-form drawing into a two-dimensional, nanoscale structure made of DNA.
DNA find
A Queensland University of Technology-led collaboration with University of Adelaide reveals that Australia's pint-sized banded hare-wallaby is the closest living relative of the giant short-faced kangaroos which roamed the continent for millions of years, but died out about 40,000 years ago.
DNA structure impacts rate and accuracy of DNA synthesis
DNA sequences with the potential to form unusual conformations, which are frequently associated with cancer and neurological diseases, can in fact slow down or speed up the DNA synthesis process and cause more or fewer sequencing errors.
Changes in mitochondrial DNA control how nuclear DNA mutations are expressed in cardiomyopathy
Differences in the DNA within the mitochondria, the energy-producing structures within cells, can determine the severity and progression of heart disease caused by a nuclear DNA mutation.
Switching DNA and RNA on and off
DNA and RNA are naturally polarised molecules. Scientists believe that these molecules have an in-built polarity that can be reoriented or reversed fully or in part under an electric field.
New DNA synthesis technique promises rapid, high-fidelity DNA printing
Today, DNA is synthesized as an organic chemist would, using toxic chemicals and error-prone steps that limit accuracy and thus length to about 200 base pairs.
The changing shape of DNA
The shape of DNA can be changed with a range of triggers including copper and oxygen - according to new research from the University of East Anglia.
More Dna News and Dna Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.