Water: more complicated than previously thought

I had not thought that water was a poorly understood substance. Here are two interesting water articles that show that there is still more to learn. Who knew.

First, if you put water in a high DC current it can form a bridge between two beakers:

When exposed to a high-voltage electric field, water in two beakers climbs out of the beakers and crosses empty space to meet, forming the water bridge. The liquid bridge, hovering in space, appears to the human eye to defy gravity.

Upon investigating the phenomenon, the scientists found that water was being transported from one beaker to another, usually from the anode beaker to the cathode beaker. The cylindrical water bridge, with a diameter of 1-3 mm, could remain intact when the beakers were pulled apart at a distance of up to 25 mm.

Why water would act this way was a surprise, Fuchs told PhysOrg.com. But the group's analyses have shown that the explanation may lie within the nature of the water's structure. Initially, the bridge forms due to electrostatic charges on the surface of the water. The electric field then concentrates inside the water, arranging the water molecules to form a highly ordered microstructure. This microstructure remains stable, keeping the bridge intact.

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The researchers noticed a pattern with the inner structures: every experiment started with a single inner structure, which then decayed into additional structures after a few minutes of operation. The group thought that this decay might be caused by either dust contamination or the increasing temperature of the water bridge under the electric field. As the water temperature increased from 20 degrees Celsius to more than 60 degrees Celsius -- which took about 45 minutes -- the bridge collapsed.

The actual paper is here.

Hat-tip: Slashdot

In other news, thin layers of water can be stabilized as ice at room temperature using a sodium and diamond coatings:

Harvard physicists have shown that specially treated diamond coatings can keep water frozen at body temperature, a finding that may have applications in future medical implants.

Doctoral student Alexander Wissner-Gross and Efthimios Kaxiras, physics professor and Gordon McKay Professor of Applied Physics, spent a year building and examining computer models that showed that a layer of diamond coated with sodium atoms will keep water frozen up to 108 degrees Fahrenheit.

In ice, water molecules are arranged in a rigid framework that gives the substance its hardness. The process of melting is somewhat like a building falling down: pieces that had been arranged into a rigid structure move and flow against one another, becoming liquid water.

The computer model shows that whenever a water molecule near the diamond-sodium surface starts to fall out of place, the surface stabilizes it and reassembles the crystalline ice structure.

Simulations show that the process works only for layers of ice so thin they're just a few molecules wide -- three nanometers at room temperature and two nanometers at body temperature. A nanometer is a billionth of a meter.

The layer should be thick enough to form a biologically compatible shield over the diamond surface and to make diamond coatings more useful in medical devices, Wissner-Gross said.

The researchers hope to us the ice layers to smooth out rough edges in diamonds used in medical implants.

The paper reporting these findings is here.

Further, Doctor-to-be Wissner-Gross has a fabulous video that shows the molecular simulations of water under various conditions, complete with stirring music. Check out the video here. His website is here.