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Fridge magnet

Researchers at the University of Cambridge have discovered an inexpensive and non-toxic alloy which gets colder when placed in a magnetic field and claim the material could usher in a new type of refrigerator that would be up to 40 per cent more efficient than current models.

The alloy, which is a blend of cobalt, manganese, silicon and germanium, is susceptible to the magnetocaloric effect (MCE), whereby a magnetic field causes certain materials to get warmer (a positive MCE) or cooler (a negative MCE).

Although the effect was discovered more than 120 years ago, it is only recently that magnetocaloric materials have been known with the right properties for use in everyday refrigeration.

Until now certain factors have meant that that the materials - typically metal alloys - were unsuitable for reasons of expense or toxicity, with the most effective solutions either containing the prohibitively expensive element gadolinium or poisonous arsenic.

But the Cambridge team’s alloy is neither costly or toxic and generates significant cooling at room temperature. The key to the magnetocaloric behaviour is a sudden change in the magnetic state of the compound, known as a magnetic transition. The material is magnetic because it contains metal atoms that themselves act like tiny bar magnets.

As the alloy is warmed up from subzero temperature, there comes a point where these atomic magnets abruptly change the way in which they are lined up. This switch occurs at different temperatures when the material is placed in a magnetic field. So applying such a field can trigger the magnetic transition and the resulting realignment of atomic magnets can then cause the material to lose heat and become colder - in other words showing a negative MCE.

The material could act as a heat pump for refrigeration. Applying the magnetic field triggers cooling. Then the field is switched off and the material absorbs heat from its surroundings, cooling them down. Then the cycle is repeated, with more heat being sucked from the surroundings each time.

More efficient refrigeration would be extremely welcome in a world plagued by high energy bills and environmental problems. But the team say their technology could go beyond the kitchen fridge to have other cooling applications because their new magnetocaloric material can be tuned to work of a wide temperature range.

University of Cambridge: http://www.cam.ac.uk/

Table-top technology

The PC will continue to dominate the way most of us use computers for many years to come.

But while ideal for communicating remotely with people, sometimes a single computer terminal feels a little too “personal” for the job in hand.

For example, if a small group working on the same project crowds around a PC it can be difficult for everyone to get a good view of the screen or access the mouse or keyboard.

Japanese scientists at Mitsubishi Electric Corporation say they have come up with a solution to the problem by turning to that humble furnishing the table for help.

The company’s DiamondTouch displays a PC screen on a high-tech tabletop, while people sit around it using their fingers to create and manipulate projected virtual objects. It facilitates small group collaboration by providing a display interface that allows users to maintain eye contact while interacting with the display simultaneously, they say.

The 42-inch screen, which takes up almost all of the 47-inch tabletop, has an array of antennas, touch sensors that conduct electricity, embedded into the surface.

Up to five people sit on a pad that conducts a harmlessly low current which passes through the body unnoticed. The system can recognise a user’s unique current and therefore knows who is touching the surface. This allows multiple, simultaneous users to interact in an intuitive fashion.

The signals generated by human contact connect to a computer which projects images from on to the surface of the table using an overhead projector. Each user’s marking are also shown on the surface in a unique colour.

Though touch panel technology isn’t normally used in PCs, it is found in other common appliances such as ATM machines and car-navigation equipment.

The developers foresee the technology having applications in areas such as government decision-making, education and games, although at as much as $10,000 each the price may have to drop before the system is adopted beyond the confines of university research facilities.

Mitsubishi Electric: http://global.mitsubishielectric.com/

Liquorice cancer care

Recent studies have revealed that liquorice compounds could be a key component for cheaper, more effective liver cancer treatment, according to the periodical Chemistry and Industry.

Liver cancer is one of the deadliest of cancers as surgery, the best option, is unsuitable for most patients while liver tumours are very resistant to chemotherapy.

Research in mice at Nankai University, China, showed that liquorice compounds glycerrhetinic acid and glycerrhizic acid preferentially accumulate in the liver. As a result, they can be used as liver targeting drug carriers.

In tests the compounds proved more efficient tissue-specific drug carriers than traditionally used antibodies or oligopeptides, compounds which yield multiple amino acids. In addition, the liquorice-derived acids are “tens of thousands of times” cheaper and easier to isolate than current carriers, according to the researchers.

The scientists claim that the technology would allow tissue-specific drugs to provide more effective treatment because a higher concentration of the drug would reach the tumour. This would reduce the dose required and cut sharply the toxic effects of the drug in other areas of the body.

Nankai University: http://www.nankai.edu.cn/english/

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