Scientists have made synthetic 'sea shells' from a mixture of chalk and polystyrene cups -- and produced a tough new material that could make our homes and offices more durable.A team of materials scientists and chemists have taken inspiration from sea shells found on the beach to create a composite material from dissimilar 'ingredients'.Their technique could be used to make ceramics with high resistance to cracking -- which could in turn be used in crack-resistant building materials and bone replacements.Writing in the journal Advanced Materials, scientists from The University of Manchester and The University of Leeds report that they have successfully reinforced calcium carbonate, or chalk, with polystyrene particles that are used to make drinks cups.They have developed an effective method of combining calcite crystals with polystyrene particles -- and have found this makes the material more ductile compared to its original brittle form.They report that the polystyrene also acts as a toughening agent, assisting the prevention of the growth of cracks.Scientists also observed that when the reinforced material cracked, the polymer lengthened within the cracks -- a well-known mechanism for absorbing energy and enhancing toughness.Researchers say their method allows the properties of the new material to be tweaked by The School of Materials at The University of Manchester, said: "The mechanical properties of shells can rival those of man-made ceramics, which are engineered at high temperatures and pressures. Their construction helps to distribute stress over the structure and control the spread of cracks. »

Most polymers -- materials made of long, chain-like molecules -- are very good insulators for both heat and electricity. But an MIT team has found a way to transform the most widely used polymer, polyethylene, into a material that conducts heat just as well as most metals, yet remains an electrical insulator.The new process causes the polymer to conduct heat very efficiently in just one direction, unlike metals, which conduct equally well in all directions. This may make the new material especially useful for applications where it is important to draw heat away from an object, such as a computer processor chip. The work is described in a paper published on March 7 in Nature Materials.The key to the transformation was getting all the polymer molecules to line up the same way, rather than forming a chaotic tangled mass, as they normally do. The team did that by slowly drawing a polyethylene fiber out of a solution, using the finely controllable cantilever of an atomic force microscope, which they also used to measure the properties of the resulting fiber.This fiber was about 300 times more thermally conductive than normal polyethylene along the direction of the individual fibers, says the team's leader, Gang Chen, the Carl Richard Soderberg Professor of Power Engineering and director of MIT's Pappalardo Micro and Nano Engineering Laboratories. »

Engineering researchers have crafted a flat surface that refuses to get wet. Water droplets skitter across it like ball bearings tossed on ice.The inspiration? Not wax. Not glass. Not even Teflon.Instead, University of Florida engineers have achieved what they label in a new paper a "nearly perfect hydrophobic interface" by reproducing, on small bits of flat plastic, the shape and patterns of the minute hairs that grow on the bodies of spiders."They have short hairs and longer hairs, and they vary a lot. And that is what we mimic," said Wolfgang Sigmund, a professor of materials science and engineering.A paper about the surface, which works equally well with hot or cold water, appears in this month's edition of the journal Langmuir.Spiders use their water-repelling hairs to stay dry or avoid drowning, with water spiders capturing air bubbles and toting them underwater to breathe. Potential applications for UF's ultra-water-repellent surfaces are many, Sigmund said. When water scampers off the surface, it picks up and carries dirt with it, in effect making the surface self-cleaning. As such, it is ideal for some food packaging, or windows, or solar cells that must stay clean to gather sunlight, he said. Boat designers might coat hulls with it, making boats faster and more efficient.Sigmund said he began working on the project about five years ago after picking up on the work of a colleague. Sigmund was experimenting with microscopic fibers when he turned to spiders, noted by biologists for at least a century for their water-repelling hairs. »

Rice University researchers have found a way to stitch graphene and hexagonal boron nitride (h-BN) into a two-dimensional quilt that offers new paths of exploration for materials scientists.The technique has implications for application of graphene materials in microelectronics that scale well below the limitations of silicon determined by Moore's Law.New research from the lab of Pulickel Ajayan, Rice's Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry, demonstrates a way to achieve fine control in the creation of such hybrid, 2-D structures.Layers of h-BN a single atom thick have the same lattice structure as graphene, but electrically the materials are at opposite ends of the spectrum: h-BN is an insulator, whereas graphene, the single-atom-layer form of carbon, is highly conductive. The ability to assemble them into a single lattice could lead to a rich variety of 2-D structures with electric properties ranging from metallic conductor to semiconductor to insulator. »

Solar cells made from silicon are projected to be a prominent factor in future renewable green energy equations, but so far the promise has far exceeded the reality. While there are now silicon photovoltaics that can convert sunlight into electricity at impressive 20 percent efficiencies, the cost of this solar power is prohibitive for large-scale use. Researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab), however, are developing a new approach that could substantially reduce these costs. The key to their success is a better way of trapping sunlight."Through the fabrication of thin films from ordered arrays of vertical silicon nanowires we've been able to increase the light-trapping in our solar cells by a factor of 73," says chemist Peidong Yang, who led this research. "Since the fabrication technique behind this extraordinary light-trapping enhancement is a relatively simple and scalable aqueous chemistry process, we believe our approach represents an economically viable path toward high-efficiency, low-cost thin-film solar cells." »

The Gran Telescopio CANARIAS (GTC) has observed an uncommon neutron star. Classified as magnetar, its nature is as peculiar as its official name: SGR 0418+5729. The observations at the largest optical telescope of the world reached an unprecedented depth at optical wavelengths for this kind of sources, helping in constraining the physical properties of this celestial body characterized by extremely strong magnetic fields.Neutron stars form when massive stars, between 10 to 50 times the solar mass, explode as supernova at the end of their life. While the external layers of the star are ejected into space, its nucleus collapses under its own weight with such a strong force that protons and electrons joins into neutron to occupy less space, reaching unbeliveably high densities and becoming neutron stars. The density is so high that these "stellar remnants concentrate a mass comparable to the one of the Sun within the volume of a sphere of only 30 kilometers of diameter, the space occupied by a large city," points out Paolo Esposito, principal investigador of the project from the Italian Institute of Astrophysics. »

Scientists in Australia are reporting the first use of ordinary cotton thread and sewing needles to literally stitch together a microfluidic analytical device -- microscopic technology that can transport fluids for medical tests and other purposes in a lab-on-a-chip. The chips shrink room-sized diagnostic testing equipment down to the size of a postage stamp, and promise revolutionary applications in medicine, environmental sensing, and other areas.Their study is in ACS Applied Materials & Interfaces, a monthly journal.Wei Shen and colleagues note that the development of low-cost "lab-on-a-chip" diagnostic tests has become an attractive area of research. Existing devices require etching microscopic channels onto slivers of silicon, glass, ceramics, or metal in a costly, complicated process. The scientists set out to find an alternative, and did so with cotton thread, which wicks fluids along its tiny fibers. »

A class of molecules whose size, structure and chemical composition have been optimized for photonic use could provide the demanding combination of properties needed to serve as the foundation for low-power, high-speed all-optical signal processing.All-optical switching could allow dramatic speed increases in telecommunications by eliminating the need to convert photonic signals to electronic signals -- and back -- for switching. All-optical processing could also facilitate photonic computers with similar speed advances.Details of these materials -- and the design approach behind them -- were reported February 18th in Science Express, the rapid online publication of the journal Science. Conducted at the Georgia Institute of Technology, the research was funded by the National Science Foundation (NSF), the Defense Advanced Research Projects Agency (DARPA) and the Office of Naval Research (ONR). »

AA software program created by an engineer at the University of Wisconsin-Milwaukee (UWM) can not only predict the types of specialized cells a stem cell will produce, but also foresee the outcome before the stem cell even divides.The software, developed by Andrew Cohen, an assistant professor of electrical engineering, analyzes time-lapse images capturing live stem cell behaviors. It will allow scientists to search for mechanisms that control stem cell specialization, the main obstacle in advancing the use of stem cell therapy for treatment of disease. It could also lead to new research into causes of cancer, which involves cells that continuously self-renew.Stem cells play a key role in human development, and also offer the potential to repair tissues or organs damaged by disease or injury. But, in order to use stem cell-based therapies, biologists need to better understand the mechanisms that control stem cell differentiation."This is a brand-new set of tools for developmental biologists," says Cohen, "and it supports an area where no other predictive solutions exist."The research is published Feb. 7 in the journal Nature Methods. Co-authors are Michel Cayouette and Francisco Gomez neurobiologists at the Institut de recherches cliniques de Montreal, and Badri Roysam, a computer engineering professor at Rensselaer Polytechnic Institute. »

While airplane and rocket experiments have proved that gravity makes clocks tick more slowly -- a central prediction of Albert Einstein's general theory of relativity -- a new experiment in an atom interferometer measures this slowdown 10,000 times more accurately than before, and finds it to be exactly what Einstein predicted.The result shows once again how well Einstein's theory describes the real world, said Holger Müller, an assistant professor of physics at the University of California, Berkeley."This experiment demonstrates that gravity changes the flow of time, a concept fundamental to the theory of general relativity," Müller said. The phenomenon is often called the gravitational redshift because the oscillations of light waves slow down or become redder when tugged by gravity. »