Chemistry

How do grains flow out of an emptying silo? And what about sugar poured out by a pastry chef?

Researchers at Centre de Physique Moléculaire Optique et Hertzienne (CPMOH) of CNRS/ Université Bordeaux 1 have just demonstrated that even without an attractive force between grains in flowing sand, they have a cohesion similar to that of liquids. These results were published in Physical Review Letters.

The surface of a liquid is similar to an elastic membrane under tension, which causes things like the pressure on the interior of soap bubbles. This “surface tension” is due to cohesion forces between molecules in the liquid.

The familiar pencil-lead form of carbon, graphite, consists of layers of carbon atoms tightly bonded in the plane but only loosely bonded between planes; because the layers move easily over one another, graphite is a good lubricant. In fact these graphite layers are graphene.

Graphene is the two-dimensional crystalline form of carbon: a single layer of carbon atoms arranged in hexagons, like a sheet of chicken wire with an atom at each nexus. As free-standing objects, such two-dimensional crystals were believed impossible to create -- even to exist -- until physicists at the University of Manchester actually made graphene in 2004.

Due to the material's unexpected electronic properties, it could have novel practical applications like tunable optical modulators for communications and other nanoscale electronics.


It’s stronger than steel and nylon, and more extensible than Kevlar.

What is this super-tough material? Spider silk; and learning how to spin it is one of the materials industries’ Holy Grails.

John Gosline has been fascinated by spider silks and their remarkable toughness for most of his scientific career. He explains that if we’re to learn how to manufacture spider silk, we have to understand the relationship between the components and the spun fibre’s mechanical properties; which is why he is focusing on major ampullate silk, one of the many silks that spiders spin. According to Gosline, spiders use major ampullate silk for draglines and to build the frame and radial structures in webs, all of which have to deform and absorb enormous amounts of energy without fracturing.

Titanium is the lightweight metal of choice for many applications and a non-melt consolidation process being developed by Oak Ridge National Laboratory may make it cheap enough to bulletproof your Prius. Or a military vehicle, if you want to be predictable.

The new processing technique could reduce the amount of energy required and the cost to make titanium parts from powders by up to 50 percent, making it feasible to use titanium alloys for brake rotors, artificial joint replacements and armor for vehicles.

The lightweight titanium alloy also improves the operation of the door and increases mobility of the vehicle, making it even more useful to the military.

A type of plastic that exhibits metallic and semi-conductor-like properties will be described in an inaugural doctoral lecture at the University of Leicester on Wednesday June 4th(*).

In his lecture, Dr. M. A. Mohamoud will discuss a novel class of materials called “conducting polymers.” Conducting polymers are smart materials that can mimic biological systems and can be used as components of artificial nerves, electronic noses/tongues, drug-release-and-delivering systems, and artificial muscles.

They can also be used as energy storage devices in battery technology, electrochromic display devices (in smart window technology and light emitting diodes), and biological sensor technology.

Nano-whatever is all the rage. They're a big deal because they can make a blacker version of black and lots of other things but what does that even mean?

Richard Compton and his team at Oxford University are here to help make carbon nanotubes understandable to everyone - namely, by making it relevant to food. They have developed a sensitivity technique to measure the levels of capsaicinoids, the substances that make chilis hot, in samples of hot sauce. They report their findings in The Analyst.

The current industry procedure is to use a panel of taste-testers, which is highly subjective. Compton’s new method unambiguously determines the precise amount of capsaicinoids and is not only quicker and cheaper than taste-testers but more reliable for purposes of food standards; tests could be rapidly carried out on the production line.


CSIRO researchers have discovered a new class of fatty acids -- alpha-hydroxy polyacetylenic fatty acids -- that they say could be used as sensors for detecting changes in temperature and mechanical stress loads.

CSIRO Entomology business manager, Cameron Begley, said researchers believed the discovery opened up an entirely new class of chemistry. “Some of these alpha-hydroxy polyacetylenic fatty acids act as indicators for a range of different conditions, such as mechanical stress or heat, and display self-assembling properties. Others display anti-microbial properties,” he said.


In the rapid and fast-growing world of nanotechnology, researchers are continually on the lookout for new building blocks to push innovation and discovery to scales much smaller than the tiniest speck of dust.

In the Biodesign Institute at Arizona State University, researchers are using DNA to make intricate nano-sized objects. Working at this scale holds great potential for advancing medical and electronic applications. DNA, often thought of as the molecule of life, is an ideal building block for nanotechnology because they self-assemble, snapping together into shapes based on natural chemical rules of attraction. This is a major advantage for Biodesign researchers like Hao Yan, who rely on the unique chemical and physical properties of DNA to make their complex nanostructures.


Your contact lenses of the future could be completely biodegradable. A soft contact lens is a hydrogel - a solid, gelatinous mass consisting of water incorporated in a polymer network.

Now Berkeley researchers have developed a technique for the formation of hybrid materials from synthetic polymers and proteins, fusing the biological functions of proteins with the processing properties of plastics.

Aaron P. Esser-Kahn and Matthew B. Francis say they have successfully synthesized a green-fluorescing biodegradable gel that responds to changes in pH value and temperature. These polymer-protein hybrid materials can also be used in sensors, nanomachine parts, or drug-delivery systems.

Cracks in buildings that close without external help may seem a little far fetched but we already have a good template in the human body's ability to heal wounds by sending blood platelets to the affected area. In most cases the healing occurs without any need for external coagulants.

The body's natural response to damage was the starting point for the development of self-repairing polymer materials with the ability to recover with minimal external help.