Archive for the ‘Chemistry’ Category

How Does Salt Melt Ice?

leave a comment »

Written by physicsgg

January 7, 2015 at 9:02 pm

Posted in Chemistry

Chemists create ‘artificial chemical evolution’ for the first time

leave a comment »

ncomms6571-f1Scientists have taken an important step towards the possibility of creating synthetic life with the development of a form of artificial evolution in a simple chemistry set without DNA.
A team from the University of Glasgow’s School of Chemistry report in a new paper in the journal Nature Communications today (Monday 8 December) on how they have managed to create an evolving chemical system for the first time. The process uses a robotic ‘aid’ and could be used in the future to ‘evolve’ new chemicals capable of performing specific tasks.
The researchers used a specially-designed open source robot based upon a cheap 3D printer to create and monitor droplets of oil in water-filled Petri dishes in their lab. Each droplet was composed from a slightly different mixture of four chemical compounds.
Droplets of oil move in water like primitive chemical machines, transferring chemical energy to kinetic energy. The researchers’ robot used a video camera to monitor, process and analyse the behaviour of 225 differently-composed droplets, identifying a number of distinct characteristics such as vibration or clustering.
The team picked out three types of droplet behaviour – division, movement and vibration – to focus on in the next stage of the research. They used the robot to deposit populations of droplets of the same composition, then ranked these populations in order of how closely they fit the criteria of behaviour identified by the researchers. The chemical composition of the ‘fittest’ population was then carried over into a second generation of droplets, and the process of robotic selection was begun again. Read the rest of this entry »

Written by physicsgg

December 9, 2014 at 1:29 pm

Posted in BIOLOGY, Chemistry

Electron Handedness Affects Gas Molecule Breakup

leave a comment »

Experiments show that beams of left- or right-handed electrons are not equal-opportunity destroyers of molecules having two mirror-image forms, which supports the idea that primordial cosmic rays generated the asymmetry in biological molecules.

An asymmetric reaction billions of years ago between electrons and the ancestors of biomolecules might explain why today’s DNA always appears as a right-handed helix. Now researchers have shown that a beam of right-handed electrons—whose spin and direction of motion align according to the right hand—breaks apart more right-handed molecules at low energies than left-handed ones. Unlike previous experiments showing such a difference, the reactions occurred in the gas phase and with low-energy electrons, which allowed for a more precise description of the electron-molecule interactions. The researchers say their results are an important step toward more direct tests of the hypothesis that nuclear asymmetries led to asymmetries in present-day biomolecules.

Many molecules come in both left- and right-handed (chiral) forms, but natural DNA is always right-handed. The asymmetry “is one of the few unsolved fundamental questions in [the] natural sciences,” says Uwe Meierhenrich, a physical chemist at the University of Nice Sophia Antipolis in France.

One possible explanation comes from nuclear physics. The radioactive decay of a nucleus is more likely to produce a left-handed electron than a right-handed one—meaning that it’s more likely to spin in the direction of your left hand’s curled fingers when you point your left thumb in the direction of its motion. When this asymmetry was discovered in 1957, “it showed us that God is not ambidextrous,” says Timothy Gay of the University of Nebraska in Lincoln. Read the rest of this entry »

Written by physicsgg

September 29, 2014 at 5:35 pm

Information Theory And The Origin of Life

leave a comment »

Christoph Adami
Research investigating the origins of life usually focuses on exploring possible life-bearing chemistries in the pre-biotic Earth, or else on synthetic approaches.
Little work has been done exploring fundamental issues concerning the spontaneous emergence of life using only concepts (such as information and evolution) that are divorced from any particular chemistry.
Here, I advocate studying the probability of spontaneous molecular self-replication as a function of the information contained in the replicator, and the environmental conditions that might enable this emergence.
I show that (under certain simplifying assumptions) the probability to discover a self-replicator by chance depends exponentially on the rate of formation of the monomers.
If the rate at which monomers are formed is somewhat similar to the rate at which they would occur in a self-replicating polymer, the likelihood to discover such a replicator by chance is increased by many orders of magnitude.
I document such an increase in searches for a self-replicator within the digital life system avida …
…

Read also

Written by physicsgg

September 10, 2014 at 2:16 pm

Posted in BIOLOGY, Chemistry, PHYSICS

Tagged with

Element Z=117 Confirmed

leave a comment »

periodicNuclear physicists have invested huge effort in creating superheavy elements, which consist of enough neutrons to provide enhanced stability from nuclear decay. For the past 30 years, experiments have been marching towards this “island of stability” with a new elemental discovery every 2 to 3 years. Part of the discovery process includes the confirmation by an independent experimental collaboration—it is only at this point that an element obtains its official status.

An international team using an intense 48Ca beam provided by GSI research facility in Darmstadt, Germany, and a target material of radioactive 249Bk supplied by Oak Ridge National Lab in Tennessee has produced two atoms of the superheavy element with atomic number Z=117, confirming the initial observation published in 2010 (see 9 April 2010 Viewpoint). In the process, a new isotope 266Lr was discovered from the previously unknown alpha-decay branch of 270Db. With a half-life of 1hour, 270Db is the longest-lived alpha emitter having an atomic number, Z, greater than 102.

The experiment is a tour de force in superheavy element research and required a detailed reconstruction of a seven-step alpha-decay chain followed by the spontaneous fission of the newly discovered 266Lr. The difficulty stems from the large variation in decay lifetimes along the alpha chain. The discovery was made feasible by the use of TASCA, a gas-filled recoil separator specifically designed for a high selectivity of superheavy or transactinide elements.

The confirmation by the TASCA team serves as a much-needed step on the long road towards the island of stability. An easier feat will be deciding on a name for Z=117. – Kevin Dusling –

Written by physicsgg

May 1, 2014 at 11:05 pm

Water surface tension with pepper and detergent

with one comment

what’s going on?
The pepper doesn’t contribute to the motion you saw but makes surface motion clearly visible. The motion results from the reduction in the water’s surface tension when detergent is added.

Surface tension is the result of the strong attraction between molecules in a liquid. Water has an unusually high surface tension compared with most other liquids because water molecules are very strongly attracted to each other. This strong attraction allows you to slightly overfill a glass with water and some insects to skate on its surface.

Detergents are members of an amazing chemical family called surfactants (short for surface active agents). Every detergent molecule has two distinct ends which chemists call the head and the tail. The tail strongly repels water while the head is strongly attracted to it. As a result, detergent molecules prefer being on the surface of water with their water repelling tails sticking up and out into the air.

When you first add detergent to water, the molecules scurry across the surface with their heads down and tails sticking up. Once the surface is full, the remaining detergent molecules begin forming small droplets called micelles by joining their tails. This effectively hides the hydrophobic tails from the surrounding water – but that’s another story.

Now, detergent heads are attracted to water, but not nearly as strongly as water molecules are attracted to each other. This is why detergents reduce the surface tension of water. Imagine a long line of people all holding hands and pulling each other together. The line is under tension. If a person near the middle lets go of both hands, everybody falls away from that person to either side. The tension has been broken. In a similar way, water molecules on the surface pull away from where you add detergent.

This trick only works well once because the detergent molecules that cover the surface of water stay there. But try sprinkling on more pepper – you’ll see cool surface motion as the dry pepper absorbs some of the detergent…

Read more at and Marangoni effect

Written by physicsgg

April 19, 2014 at 2:46 pm

Xenon Bonds

leave a comment »

Periodic Table of Videos

xenonAsked about “special bonds” – the Professor recalls some chemical tales involving “unreactive” Xenon.

Written by physicsgg

September 27, 2013 at 1:29 pm

Posted in Chemistry

Tagged with

Crystals jump and explode in ultraviolet light

leave a comment »

Light makes crystals leap 1000 times their own length

That’s one giant leap for inanimate matterMovie Camera. Light has prompted crystals up to a millimetre long to jump distances a thousand times their own length, a capability that could one day power tiny machines.

Pance Naumov of New York University in Abu Dhabi noticed the power that light can have on crystals in 2010, when he saw crystals of green fluorescent protein bend to more than 90 degrees under weak illumination.

Now he and his colleagues have seen tiny crystals containing cobalt, chlorine and nitrate groups leaping too, under ultraviolet light – and examined the process in more detail.

“It’s fascinating,” Naumov says. “What really impressed me is the magnitude of the response..”

Artificial muscle

Besides hopping, some crystals rolled or flipped, whereas others split off fragments or broke into two equal pieces. Light that was bright, but not quite as intense as sunlight on a clear day, prompted motion in a fraction of a second, but crystals exposed to much dimmer light took up to 20 seconds to respond.

The jumping response seems to be down to the way light energy causes atoms in the crystal to rearrange themselves, leading to a build-up of strain that is then explosively released.

Naumov says that heat should reverse these atomic rearrangements. So by alternately applying light and heat, the jumping crystals might be used to open and close micro-scale fluid valves or to form flexing artificial muscles.

“It is especially interesting that the mechanical energy is provided by a reversible chemical change,” says chemist Philip Coppens of the University of Buffalo in New York State, who was not involved in the work.


Written by physicsgg

August 8, 2013 at 1:18 pm