Science

Web of secrets: spider silk has many incredible properties Spiders don’t spin when hanging from their webs because their silk dissipates energy by partially deforming when twisted. This is the conclusion of Dabiao Liu from Queen Mary University of London in the UK and colleagues, who have investigated the unusual ability with the hope it can be mimicked in synthetic fibres. Spiders produce various types of silk, each with different properties for specific purposes. For the outer rim and spokes of their webs, they use dragline silk, which has incredible strength comparable to high-grade steel. Spiders also use this silk to lower themselves from heights. But, rather unusually, spiders do not spin uncontrollably on their threads as they descend. “Spider silk is very different from other, more conventional materials,” says Liu. “We find that the dragline from the web hardly twists, so we want to know why.” The team tested the silk of two species …

Come together: sharing an office is more than just social Working near each other can boost collaboration among researchers, according to a team at Massachusetts Institute of Technology (MIT) in the US. Matthew Claudel and colleagues examined the relationship between researchers’ collaborations and their physical proximity with each other around the MIT campus. By analysing 40,358 papers and 2350 patents covering MIT research between 2004 and 2014, they found that spatial relationship was more important than departmental and institutional structures. “Intuitively, there is a connection between space and collaboration,” says Matthew Claudel. “That is, you have a better chance of meeting someone, connecting, and working together if you are close by spatially.” Campus-wide study The study confirms and extends the Allen Curve – a theory by Thomas Allen in the 1970s that proposed collaboration and interaction decrease as a function of distance. Allen even found that basic conversations were less like to occur when people …

Cryptography in space: the SOTA instrument Physicists in China have achieved the first quantum teleportation from Earth to a satellite, while their counterparts in Japan are the first to use a microsatellite for quantum communications. Both achievements suggest that practical satellite-based quantum communications could soon be a reality. Jian-Wei Pan of the University of Science and Technology of China in Hefei and colleagues used China’s $100m Quantum Experiments at Space Scale (QUESS) satellite to receive a quantum-teleported state. This was done over a distance of 1400 km from a high-altitude (5100 m) ground station in Tibet to QUESS. This is more than 10 times further than the 100 km or so possible by sending photons through optical fibres or through free space between ground-based stations. Entangled transmission Described in a preprint on arXiv, the process involves creating photons that are quantum-mechanically entangled and then transmitting them to QUESS. Last month, Pan and colleagues reported the distribution of quantum …

Caught in a trap: caesium atoms diffusing in rubidium Physicists at the University of Kaiserslautern in Germany have observed how individual atoms diffuse through a gas for the first time, and how individual collisions between particles affect diffusion. The new study could help model diffusion in rarefied environments, such as thin layers of air in the upper atmosphere, in interstellar space or in vacuum systems. Diffusion is the process whereby tiny particles uniformly disperse throughout a gas or liquid. Although these media are made up of individual particles, researchers usually describe diffusion as a continuous process. Diffusion was first described by the Scottish botanist Robert Brown, who observed that grains of pollen appear to quiver as they zigzag through a liquid. This movement came to be known as Brownian motion and it allows substances to disperse and mix. Albert Einstein, in his seminal 1905 paper, explained diffusion at the microscopic level and showed that Brownian …

Circle of life: molecules left over from a dead star typically found where stars are born Two previously unseen molecules have been detected within the remnant of supernova 1987A. Using the Atacama Large Millimeter/submillimeter Array (ALMA), Mikako Matsuura from Cardiff University in the UK and colleagues have found formylium (HCO+) and sulphur monoxide (SO) alongside previously detected compounds such as carbon monoxide (CO) and silicon oxide (SiO). Supernova 1987A (SN 1987A) is located 163,000 light-years away and its dramatic explosion was witnessed, as the name suggests, in 1987. Observations over the following 30 years have revealed details about how stars die and how their atoms – such as carbon, oxygen and nitrogen – spread into space. In the past, scientists believed the molecules and dust present within a star would be destroyed during a supernova explosion. However, observations of molecules in SN 1987A suggest otherwise, and the current study, presented in Monthly Notices of the Royal Astronomical …

The Graphene Flagship has announced two new experiments that will be testing the viability of using graphene in space applications. The projects will start in November 2017 in collaboration with the European Space Agency (ESA). Graphene Flagship, a European Union research initiative, explores the potential of using single-atom-thick carbon in new technologies. A major part of the programme is to train students and young researchers. One of the experiments will be led by graduate students at Delft Technical University in the Netherlands. Their work will also be part of an ESA Education programme called Drop Your Thesis!, which offers students an opportunity to design experiments for the ZARM Drop Tower in Germany. Using the free-fall microgravity conditions generated in the tower, the researchers will test graphene light sails made by Graphenea. Their aim is to understand how much thrust can be generated when a laser light is shone on the graphene membranes, which could lead …

Spot on: 10 interacting lasers (left) mostly synchronize their phases, while 20 produce more topological defects A new way of using a laser cavity to study the emergence of topological defects has been unveiled by researchers in Israel. Topological defects emerge when a system makes a rapid transition from a disordered to an ordered phase – a process called quenching because it often involves rapid cooling. In the case of magnetic order, quenched magnetic moments form small domains in which the moments point in the same direction. Moments in neighbouring domains can point in different directions and the interfaces between domains are called topological defects. These defects can occur in a wide range of systems, from atomic gases to the rapidly cooling early universe. Understanding how to eliminate topological defects could even be exploited to solve hard computational problems. Multiple lasers How topological defects emerge can be very tricky to study in the laboratory because …

Multiple ions: how the nodes could be used in a quantum computer A node for quantum computing that uses two different species of ion has been unveiled by Chris Monroe and colleagues at the University of Maryland in the US. The system uses a barium ion to communicate externally via light and a ytterbium ion to store quantum information. Trapped ions show great promise for use in quantum computers because they can store quantum information for long periods of time and can also be made to interact with photons, which serve as carriers of quantum information. A practical quantum-computing node must be able to do both of these things at the same time, and this is a significant challenge because the ions that are very good at storing information are usually not very good for interacting with photons and vice versa. Long coherence time One possible solution is to use two different types of ion …

Good vibrations: tracking the motion of atoms in iron selenide Two important breakthroughs in the understanding of iron-selenide superconductors have been made by two independent research groups. One team has shown that the electrons responsible for superconductivity in the material probably come from a specific atomic orbital. The other team, meanwhile, has measured the interaction between electrons and atomic vibrations in iron selenide, which is believed to be involved in its superconductivity. The research could shed light on the mystery of why some materials based on iron selenide are superconductors at relatively high temperatures, which has puzzled physicists for more than a decade. While bulk iron selenide is a superconductor below 8.5K, this transition temperature can reach as high as 75K when an ultrathin trilayer of the material is grown on certain substrates. Multiple orbitals The superconductivity in iron selenide is thought to arise when electrons form Cooper pairs, which can then form a low-temperature …

Cubist light: images of a cube illuminated from three different directions A new nanostructured flat surface that appears like a 3D object – complete with realistic light shading and shadows – has been developed by Alexander Minovich, Anatoly Zayats and colleagues at Kings College London and the Rheinische Friedrich-Wilhelms-Universität Bonn. The optical illusion relies on a computer-graphics technique called “normal mapping”, which creates 3D objects with realistic lighting effects on a 2D display. The surface comprises a gold film 180 nm thick that is covered with a 105 nm layer of magnesium fluoride. Squat rectangular pillars of gold 30 nm tall are arranged in an array on the surface of the magnesium fluoride, which acts as a transparent spacer between the gold film and the pillars. Shadow and contrast Normal mapping was then used to compute the orientation of each pillar so that light reflecting from the surface appears as a cube (see figure). What is more, when …

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