A Sweet Sense

By: David Bradley

A glowing report from a molecule could make life easier for diabetic patients by allowing them to continually monitor levels of glucose in their blood without the need for a pinprick test. The technique being developed by researchers at Strathclyde University in Glasgow and Guy's Hospital in London also offers a healthy view of how well physics, chemistry and biology can work together.
  As millions of diabetic people worldwide know, needles are a pain. It is not just the repeated need to inject insulin which is unpopular, but also taking pinprick blood samples to monitor blood sugar levels every day, whether at a visit to the doctor or at home. According to David Birch of Strathclyde University, "Non-invasive glucose sensing is a priority to improve the everyday management of patients with diabetes mellitus, especially for detection of hypoglycaemia (low blood glucose concentrations)."
  Birch and colleague John Pickup at King's College London-Guy's Hospital and their teams are working together to design a simple device that might be implanted under the skin to continuously monitor blood sugar from outside the body. The device should help patients keep closer tabs on their blood sugar and so help them prevent dangerous increases in blood glucose that are thought to lead to the damaging long-term effects of diabetes, such as kidney, eye and nerve disease, by injecting their insulin precisely when it's needed; even when they are driving, operating machinery or asleep.
  The scientific challenges have been mainly those associated with crossing disciplines, a recognised frontier for the new millennium. "Physicists traditionally love relatively simpler systems such as atoms because they offer the best chance of furthering our fundamental understanding of matter," Birch told us. "However, life is essentially a molecular phenomenon and the molecules that matter most in nature are complex and rarely play by the physicists rulebook as we know it, but they seem to know what they are doing alright!"

Molecular structure of glucose - C₆H₁₂O_{6 (chemical formula)}

Absolutely Fabulous

The secrets of clouds of atoms, quantum entanglement and antimatter might one day be revealed with a little help from British physicists.
  "Everything has suddenly come together after 18 months of struggling to make things work," that's what Ed Hinds told us, "Both our atom chip experiments are suddenly producing fantastic data!" he added. Hinds tale is a chilling one of experiments that reach the coldest parts of nature with a view to building new quantum devices using ultracold atoms instead of electrons.
  Absolute zero is unimaginably cold. An industrial deep-freeze is balmy in comparison. How about liquid nitrogen, the classic undergraduate demonstration material for smashing daffodils and rubber gloves? Even that's at a relatively scorching 63.25 degrees above absolute zero. Might the darkest depths of space at an almost clement 3 degrees above absolute zero be adequate?
  Hinds thinks not. He and his team work at less than a millionth of a degree above the coldest of cold. At this temperature, whole atoms act like waves instead of particles and follow the strange rules of quantum mechanics. "We start to see quantum effects, such as interference, in the motion of whole atoms, not just the electrons within them," Hinds explains, "Being able to manipulate clouds of atoms as quantum objects is already very exciting," says Hinds. It could also be very practical paving the way for making quantum circuits with atoms.
  Such devices are still some way off. "At the moment, we know very little about how to use these new quantum effects for useful applications," concedes Hinds, "but it is clearly very powerful and theorists are working hard on thinking about this." Ultimately, interference between many quantum logic gates - on an atom chip - might provide a blueprint for a quantum computer; "the most exciting prospect of all," he enthuses.

Spark-free Motoring

Avoiding sparks from any machinery in an explosive environment is essential for safety. Now, a new type of centrifugal control switch that uses a fluid magnetic material could be used to remove the risk of sparking from switching an induction motor on and off in such volatile environments. Induction motors themselves do not produce sparks like a conventional motor so are perfectly suited to factories and other premises where organic solvents, dry powders and other flammable materials might be in use.
  R. P. Bhatt of the Department of Physics, Bahauddin Government Science College, in Junagadh, India, points out, in a forthcoming issue of the Journal of Magnetism and Magnetic Materials, how magnetic fluids have come to the fore as interesting materials for a range of potential applications. He believes, however, that they could also be used in the development of switching and governor devices for controlling electrical machines, such as motors. Bhatt and his colleagues have now developed just such a device based on the idea of centrifugal switching in which the speed of a motor is regulated by its own speed. Centrifugal force increasing the faster the motor rotates until the switch cuts the supply at a pre-determined limit. Once the motor slows, the fall in centrifugal force allows the switching device to resume its original position and so the motor is switched back on.
  Normally, a switch will occasionally generate sparks, which can be disastrous in a flour mill, a chemicals factory or other potentially explosive environments. Bhatt's centrifugal switch utilises a magnetic fluid as one of the switching elements. Because there is no possibility of spark-inducing friction between this fluid and the switch's terminals, the risk of explosion or fire is quelled.
  Bhatt's switch has four main components: a transformer-type transducer; a non-magnetic vessel; a switching element and a magnetic fluid. The magnetic fluid fills the non-magnetic vessel and this is attached to the shaft of the motor. "When the motor rotates," explains Bhatt, "centrifugal force pushes the magnetic fluid to the periphery of the vessel, where the fluid completes the magnetic circuit of the transformer." The flux linkage of the transformer thus changes and the value of its secondary output voltage is increased. The increase depends on how much magnetic fluid has moved on to the periphery due to centrifugal force and so how fast the motor is spinning. The device is thus a simple but smart speed detector. An electronic circuit detecting this voltage change can thus be used to regulate the power supply to the motor with no need for spark-producing mechanical switching. DOI: 10.1016/S0304-8853(02)00613-3