This year’s Nobel Prize winners were announced across the 6th-10th October. In November’s print issue, we looked at the achievements of the winners or winning teams in each of the three science categories in more detail.
The Nobel Prize in Physiology or Medicine this year was jointly awarded to John O’Keefe and to Edvard Moser and May-Britt Moser for their discovery of cells that constitute a positioning system in the brain, helping to better understand how people orient themselves in space.
The first component was discovered in 1971 by John O’Keefe. He recorded signals from individual nerve cells in the hippocampus of rats and saw that certain cells were activated whenever the rats assumed a particular place in their environment. He was then able to demonstrate that the cells were building up an inner map of the environment, and that the hippocampus generates numerous maps and that the memory of an environment as a specific combination of activated cells in the hippocampus.
In 2005, a second component of the positioning system was found, by Edvard and May-Britt Moser of Norway; another type of nerve cell they referred to as “grid cells”, which generate a coordinate system and allow for precise positioning and path-finding. They went on to show how the combination of place cells and grid cells allow the brain to determine position and to navigate.
Isamu Akasaki, Hiroshi Amano and Shuji Nakamura received the 2014 Nobel Prize in Physics for the invention of the blue light emitting diode (LED).
Having made their breakthrough in the early 90s, this may seem to us now a commonplace technology, but as Staefan Normark of the Royal Swedish Academy of Sciences, which determines the prize winners, explains, “Red and green diodes had been around for a long time, but without blue light, white lamps could not be created”. The first practical visible-spectrum (red) LED was invented in 1962.
LEDs are made from layers of semiconducting materials. These materials would traditionally be poor conductors. Impurities can be added to the material, to modify the electrical properties of semiconductors. They will then have either an excess or a deficiency of electrons, and these materials can be paired up so that when a current is applied, the electrons can diffuse across the junction between the two materials and pair up with “holes” – in quantum physics, a space where an electron could potentially exists but there is none – and energy is released. In the case of LEDs, this energy is released in the form of light.
LEDs are many times more energy efficient than “regular”, incandescent light bulbs, which release much of their energy as unwanted heat, as their light is produced by the heating of the filament, which glows red and then white as it gets hot. In terms of luminosity per wattage, the most recent record for LED bulbs makes them almost 30 times more efficient than regular light bulbs. Due to the low power requirements they can be powered by cheap local solar power, creating potential for improving quality of life for 1.5bn people who lack access to electricity grids. Martin Poliakoff, Vice-President of the Royal Society, commented that these scientists “have given us a new energy-efficient light source that is transforming lighting technology and has the potential to make reliable lighting accessible to all.”
The 2014 Nobel Prize in Chemistry was awarded to Eric Betzig, Stefan W. Hell and William E. Moerner “for the development of super-resolved fluorescence microscopy”.
Traditional microscopes are limited in their resolution by the wavelength of visible light; due to the diffraction of light, it they wouldn’t be able to see things clearly that are any smaller than about 200 nanometres. The techniques developed by these three scientists combine microscope imaging with advanced techniques in molecular biology and have allowed scientists to see to the level of individual molecules inside living cells. They conducted their work separately, and developed two different imaging techniques.
Stefan Hell’s technique uses two lasers emitting a series of light pulses, one working to excite molecules over a large area, causing them to fluoresce, or emit light, and the other extinguishing the fluorescence of most of the molecules within the same area, leaving just a tiny illuminated target in the centre of the field of view, avoiding the blurring together normally observed when fluorescent molecules are magnified. Gradually the whole desired area can be scanned in the same way to build up an image with very high resolution.
The technique developed independently by both Betzig and Moerner is known as single-molecule spectroscopy. Essentially, it uses a pulse of light to activate a few flourescent molecules spread out across the sample, far enough apart from each other that they can each be resolved to create a high-resolution image. This is then repeated for a more subsets of molecules and all of the images are superimposed to create a complete set.