- Saturday, 27 August 2016 15:09
by Dr. Atta-ur-Rahman
Prof. Dr. Atta-ur-Rahman is the most decorated scientist of Pakistan having won four civil awards by the Government of Pakistan
The Incredible World of Smart Materials
Imagine you are driving a car and the car is involved in an accident - the car is dented. You get out of the car and start smiling. The car is made of a memory alloy, so the dented material repairs itself, as if by magic, and the dent disappears as the material restores itself to its original shape. What about the paint job necessary? No worries! The car has been painted with a self healing paint which when scratched can heal itself. Science fiction? No, such materials are already here.
Rapid advances in nanotechnology, information technology and synthetic chemistry are opening up new worlds of exciting intelligent materials. The new smart materials can heal themselves if damaged since the original shape is “remembered” by them, change their shape (“morph”) in response to electric currents or magnetic fields, and serve as powerful bullet proof “living” exo-skeletons which can be worn by Robo-Cop type soldiers during combat. These suits when connected to the neural systems of the soldier, can react instantly to commands. The program is spear-headed by the Defense Advanced Research Projects Agency (DAPRA) of the Department of Defense in USA and is being implemented by the US Army Research Office (ARO), Office of Naval Research (ONR), NASA Langley Research Center and the Space Operations Vehicle Technology Office at Wright Patterson Air Force Base. The new alloys being used in aircraft can change their shapes in response to electrical signals triggered by stress, and return to their original shape when the stress is removed. The Smart Memory Alloys are effectively “noise cloaked”, useful in the development of silent stealth helicopters and ground vehicles. These “living” materials mimic the biological systems, but instead of living cells, they have nano-machines incorporated into their structures. Under the CHAP (Compact Hybrid Actuator Program) initiative, carbon nano-tubes that are 600 times stronger than steel by weight, and ultra-thin films made from composite materials are being employed to produce surface skins of space craft. These provide enormous strength, reduce aircraft body weights and self-repair if damaged. Some surfaces can even store hydrogen that serves as a shield against the lethal damaging effects of cosmic radiation. Objects fabricated with new “metamaterials” can indeed be invisible.
The insect-sized drones used by foreign intelligence agencies are built with special materials having stealth properties that can evade detection. Controlled remotely, they can be maneuvered so that they can be strategically positioned on the walls and tables of the Prime Minister, President or heads of strategic organizations, recording all that goes on, and transmitting the sound and video intelligence data to receiving stations located miles away.
We live in this strange and wondrous world of science where innovation determines progress, and truth is stranger than fiction.
Science of the Invisible
Scientists have developed some special “metamaterials” which can make objects invisible to everything that travels as a wave. Both light and sound are waves and, at the sub-atomic level, even matter has wave character. These metamaterials derive their amazing characteristics of being able to bend waves away from an object because of their size and shape. When tiny concentric rings of the metamaterial are placed around an object, the material bends the light waves without any reflection or absorption. The waves of light thus go around the object, like a stream of water going around a rock, and then meet again behind it, making the object completely invisible.
The first such cloaking materials were developed by John Pendry at Imperial College London and David Smith at Duke University who worked only with microwaves but Xiang Zhang and colleagues at University of California at Berkeley later succeeded in bending visible light waves backwards. A design to cloak a submarine from sonar waves has been prepared and it has been shown that atomic waves can also be bent, since sub-atomic particles travel as waves. These researches have obvious defense applications. Indeed about 50% of all research in USA is funded by US defense agencies (NASA, ONR, US Air Force etc.).
It is high time that our armed forces start diverting major funds (at least 5% of their respective budgets) to universities, leading centers of excellence and research organizations so that Pakistan can attain leadership in such areas as metallurgy, nanotechnology, industrial microelectronics, robotics, biotechnology and computer sciences. The real strength of our country comes not from imported weapons but from having a strong knowledge economy which rids us from the paralytic dependence on others for all our technological needs - civilian or defense. Will our Chief of Army Staff make this happen?
Transparent Aluminum – Seeing Through Solid Matter
Prof. Justin Wark and colleagues at the Department of Physics in Oxford University have made an interesting discovery. When aluminum was bombarded briefly with powerful soft Xray lasers, a core electron in every atom of its crystalline structure seems to be displaced, and it becomes completely transparent. Transparent aluminum was conceived in the film Star Trek IV , but fiction now seems to have become a reality. The discovery will throw light on what is happening during the creation of “miniature stars” by high powered laser implosions and increase our understanding about harnessing the power from nuclear fusion.
In another related development, scientists working at Imperial College London and University of Neuchatel (Switzerland) have shown that it is possible to have lasers pass though solid objects. They prepared some nanocrystals and when lasers were passed through them the nano crystals became transparent. The discovery may lead to our ability to see through solid objects, such as people buried below a collapsed building, and do away with the need of X rays in medicine.
Making Objects Invisible
Magicians have been practising the art of making objects disappear for centuries. Now however science can really make objects invisible!
In 2006, Prof. John Pendry and colleagues proposed the design of a cloak that could steer light around an object, thereby making it invisible. Soon thereafter Dr. David Smith at Duke University succeeded in making such a cloaking device using certain exotic “metamaterials” having unusual electromagnetic properties. This first cloak however could only hide two-dimensional objects, and only if they were viewed at one particular frequency, not at the complete range of frequencies found in visible light.
That was four years ago. Optical cloaking devices made of silicon have now been independently built by physicists at the University of California, Berkley and Cornell University in Ithaca, New York. When these “carpet cloaks” are placed over an object, the object becomes invisible when viewed from one angle and the carpet appears flat. The limitation of the need to view an object from one particular angle for it to be invisible has recently been largely overcome by Tolga Ergin of the Karlsruhe Institute of Technology, who have used new technologies so that the object appears invisible from a wider range of angles, bringing 3D invisibility a step closer. The technology being developed has applications in defence, as it may allow soldiers, weapons, warships and planes to appear invisible.
Harry Potter’s cloak of invisibility is fast becoming a reality!
Invisibility Cloaks – Made from Invisible Threads
Metamaterials are materials that can bend light and make objects invisible if cloaked by them.
Now invisible threads are being designed and synthesized which are made of components smaller than the wavelength of light. This allows them to bend light waves and imparts optical properties not present in normal substances. Computer models indicate that such threads should not be thicker than 1 micrometer, and efforts are now under way to fabricate such threads by Alessandro Tuniz at the Institute of Photonics and Optical Science in Sydney, Australia. What does the future hold - invisible armies, ships, planes and submarines cloaked by metamaterials!
Intelligent Materials and Self-Healing Paints
Spectacular progress is being made in the development of intelligent materials that can change their shapes when electrical currents, magnetic fields or heat is applied. New alloys have been developed that have a built-in memory that allows them to remember their original shapes and which can repair themselves if cut or damaged. The US government is funding researches for development of new types of aircraft that have smart wings with the ability to flex their wings like insects and convert from bombers to fast and agile fighter aircraft in mid-flight. Nickel free titanium alloys (“NiTinol”) can remember shapes and, triggered by magnetic fields, adopt those shapes when required. Iron-palladium alloys have also been found to have remarkable shape-changing abilities due to the built-in molecular nano-machines. Carbon nano-tubes have been found to have 600 times the strength of steel. Space craft and aeroplanes may be built with such materials in the future. Self-healing materials made of long chain molecules (“ionomers”) can even heal themselves after a bullet has passed through.
Paints which have the ability to self-repair scratches use chitosan, derived from chitin, present in the shells of crustaceans (crabs, shrimps, lobsters etc.). Alternatively the paints can have tiny liquid-filled capsules which release fresh paint when damaged.
In the future you may well be riding in cars which when dented in an accident, heal themselves because they are made of such memory alloys, coated with self-healing paint.
Paper Stronger than Iron
Can paper be stronger than iron? Sure, it can! Researchers at the Royal Institute of Technology in Stockholm have prepared a special “nano-paper” which is so strong that it is bullet-proof ! The paper is made of tightly woven nano size (one millionth of a millimeter in thickness) cellulose fibres. Cellulose is the main constituent of cotton (about 90%) and wood. The bullet proof paper was prepared by digesting wood pulp with enzymes, finely chopping the fibers with a blender and then making sheets of the special nano-paper in which the cellulosic fibers were tightly intertwined in a strong network. The material was even stronger than Kevlar, a synthetic material which was initially used as a replacement for steel in racing tires.
Tougher Spider Silk
Spider silk is one of the toughest fibres known. Indeed, weight for weight, it is stronger than steel. Scientists have now developed a way to make it tougher, learning from how nature toughens insect parts. There are a number of creatures which have metals in their claws, jaws and stingers which are responsible for their strength. The mandibles of certain ants contain toughening zinc metal while the jaws of certain marine worms are strengthened by the presence of copper. Lee and Knez at the Max Planck Institute of Microstructure Physics in Halle, Germany have succeeded in impregnating spider silk with titanium, making it ten-fold stronger. By mimicking this process in artificial fibres, the scientists hope to produce super-tough textiles.
Nanotechnology for Cancer Treatment
When materials are reduced to the size of one millionth of a centimeter, they exhibit special properties which are being used in the development of new medicines, cosmetics, water purification techniques, construction and fabrication materials, and a host of other applications. Scientists working at the City University of New York have now developed nanofibres, which can take drugs to the exact diseased areas that need to be attacked. This avoids the side effects caused by these drugs on other normal parts of the body. Anti-cancer drugs attached to molecular nanofibres can be detached, in response to enzymes released by tumours so that they only attack cancerous sites.
Artificial Cartilages Bring Hope
Pain in knee joints is a common problem in elderly people. It is often due to the wear and tear of the joints. Natural cartilages, which reduce the friction between the bones, can wear out and may eventually need replacement. Efforts to develop artificial materials that can replace natural cartilages have had limited success, because the high friction exerted between the joints can result in stiffening of the synthetic materials, so that they can lose their function after a certain number of years.
Jacob Klein at the Weizmann Institute of Space in Israel has developed low friction joints made of a polymer with surface molecular brushes. These brushes attract water molecules which act as a lubricating sheath as they slide past each other, thereby lowering the friction dramatically. The material has properties comparable to natural cartilages.
Entire neighbourhoods can be destroyed by raging fires that spread rapidly if there is wind blowing, causing large scale losses of life and property each year. Houses located in congested localities or near forests are particularly vulnerable as burning embers can travel a long way and engulf them, even before the actual fire reaches them. Fires killed 173 persons last year in Australia when they were trying to save their houses and a large number of shops and buildings were recently gutted in Karachi when miscreants set fire to them.
A technology has been developed that can make houses and buildings completely fireproof. It involves covering the entire house with a completely fire-proof tent located on the roof which rolls out and inflates (just as a car air bag does) at the push of a button and covers the entire house within minutes. Two large fans come into action, pumping air into the flexible tubes of the tent that form its exoskeleton. As the tent inflates, the fabric cover unfolds and envelopes the roof and sides of the house quickly with the fireproof fabric. A similar tent was earlier used by the US army for protecting military vehicles from chemical attacks and has been adapted for civilian use.
Self-Cleaning Glass Windows
Deriving inspiration from the manner that lotus leaves are able to keep themselves clean, some scientists at Tel Aviv University, while trying to develop a cure for Alzheimer’s disease, have accidentally developed a new type of surface nano-material. The material has a surface with tiny hairs of small protein molecules (peptides) about one-millionth of a millimeter in size which are resistant to water and heat. Coatings made from this material can seal glass surfaces and keep them clean by repelling particles of dust or moisture. The material can be useful in keeping glass windows of sky scrapers clean that otherwise require a lot manual window washing. They have also been found to be useful in keeping solar panels clean from dust and dirt, increasing their efficiencies by up to 30%.
Nanotechnology: Fast Charging Hybrid Car Batteries
“Hybrid cars” working both on petrol as well as fuel cells (which use hydrogen as a store of power) or batteries (which can be electrically recharged) have been known for some years. One problem associated with such rechargeable batteries is that it takes hours to charge them. Kang and Ceder at MIT have now developed an experimental battery that charges 100 times more quickly. The battery contains “nanoballs” of lithium iron phosphate which can be charged in minutes instead of hours. Cell phones containing batteries made of such nano-materials may be charged in seconds!! The day may not be far when petrol filling stations may be replaced by “battery charging stations”.
Lightest Solid in the World Invented
Scientists working at the University of Central Florida have succeeded in preparing the lightest solid in the world. It is so light that one cubic centimeters of it weighs only 4 milligrams! It has been nicknamed “frozen smoke” since it is a translucent aerogel made of fine carbon tubes (nanotubes). Aerogels are 99.8% air, and they are a thousand times lighter than glass. They are 39 times better insulators than carbon fiber materials.
The material is springy, with the ability to be stretched thousands of times. If an ounce of the material was stretched out and the pieces placed side by side and end to end, it would cover a space equal to three football fields! It is an excellent conductor of electricity and may find a host of applications as sensors in electronics. Since it is made of fine nanostructures, membranes made from it offer exciting possibilities of use as catalysts in fuel cells and for storage of energy.
Intelligent Plastic Film
Prof. Andrew Mills and coworkers at Strathclyde University in Scotland have developed an intelligent plastic film that tells you when the food that is wrapped within it starts to go bad. The manner in which the plastic works is being kept a closely guarded secret. The film undergoes a change of colour as the food starts to go bad, alerting you about its status.
A related discovery by Researchers from Germany’s Fraunhofer Institute for Process Engineering and Packaging is the development of a special food packaging film that kills bacteria and keeps food fresh longer. The film is coated with a lacquer that contains an edible antibiotic substance. As the film touches the food, the antibiotic is released slowly, thereby killing any harmful bacteria that are generated. As a result, various foods such as meat, cheese and fish can be kept fresh longer.
Glass Stronger than Steel
Scientists at the Berkeley Lab and the California Institute of Technology (Caltech) have developed a special glass which is stronger than steel. The glass bends rather than cracks because it possesses an enormous amount of plasticity, a property incorporated into it by the presence of a small amount of palladium. The resistance to cracking in this glass is far higher than found in some of the toughest materials that have been developed previously. The glass is expected to find wide applications in defense as well as in industrial products.
Imagine that you are wearing a shirt and accidentally tear it. Then something remarkable happens. The shirt senses that a part of it has been damaged, and starts repairing itself. In a few moments, it has glued itself back at the tear and is again as good as new! Intelligent materials have been invented that remember their structure and shape and have the capability of repairing themselves if damaged.
Such self-healing materials usually incorporate microcapsules within their structures. These microcapsules get ruptured when a section is damaged, thereby releasing a liquid that acts as a sealant. Such technologies have been employed in plastics as well as in a self-healing concrete, in which the cracks that appear automatically heal themselves.
More recently biopolymers have been prepared from vegetable oils and they return to their original shape when heated. Intensive researches in this exciting field are being carried out by Dr. Michael Kessler of Iowa State University and a number of research groups in USA, Europe and Japan.
Touch Screens - from Carbon Nanotubes
There has been growing demand for touch screens for mobile phones and other devices. The most popular touch screens need to have high transparency in thin screens and excellent conductivity. These “capacitative screens” are made from an element, indium, which is in short supply on our planet. There has therefore been a search for alternatives. Researchers at the Fraunhofer institute in Germany have now developed low cost touch screens made from carbon nanotubes and low cost polymers.
Carbon nanotubes (different from carbon fibers) are extraordinarily strong, although about 50,000 times thinner than a human hair and can have a length of up to 18 centimeters. They are cylindrical carbon molecules with a length to diameter ratio greater than of any other material (about 132 million to 1). They were developed after the serendipitous discovery of “buckyballs” - football-shaped carbon molecules that were discovered by two independent groups led by Prof. Harry Kroto at Sussex University and Prof. Richard Smalley and Robert Curl at Rice University. They were exploring how certain compounds (polycyanoacetylenes) were formed in the stars and ended up heating graphite to high temperatures, resulting in the accidental discovery of football shaped pure carbon molecules. They shared the chemistry Nobel prize in 1996 for this discovery. Carbon nanotubes have found applications in many fields including electronics, optics and material sciences.
Magicians have practicing a trick for centuries - making pretty girls disappear before our very eyes. Now science can do the same by actually bending light around objects through the use of “metamaterials”. Moreover it may also be possible to replace the real objects by others, so that you see something else instead!
The researches have been carried out by Wei Xiang Jiang and Tie Jun Cui's team at Southeast University in Nanjing, China. Cui and coworkers had earlier developed the “electromagnetic black hole” for light in 2009. Now they have created a new type of metamaterial that changes the manner in which radio waves interact with copper, making it appear as if it was made of another substance. This discovery can find applications in defense, by cloaking aircraft or submarines, and making them appear as objects with another shape and not made of metal - flying birds in the sky instead of attacking planes or sharks under water instead of submarines, for instance.
Next Computer Revolution – from Graphene?
We have all heard of graphite. It comprises layers of carbon stacked together and arranged in a honeycomb pattern. If one peels off layers from it which are a few atoms thick, one obtains the material “graphene” that possesses remarkable properties. The 2010 Nobel Prize for Physics was awarded to Andre Geim and Konstantin Novoselov for their ground breaking work on the two-dimensional structure of graphene. The material shows remarkable electron mobility, with the electrons being able to zip across the surface at dazzling speed. James Tour at Rice University in Houston, Texas and coworkers have now developed a way of etching these sheets of atoms, so that portions of the material with a single layer can be formed that behaves like a metal to perform the functions of a wire. If a portion of graphene is etched differently so that a double layer is formed, it behaves as a semiconductor that can be transformed to a transistor.
Precise control in the manner the etching is carried out can thus lead to the development of super-fast computers of tomorrow.
Plastics – from Bananas, Pineapples and Coconuts
Most plastics are normally made through polymerization reactions of certain chemicals that come from petroleum or natural gas. A group of researchers at Sao Paulo University in Brazil have now found that they can manufacture excellent plastic materials starting from pineapple leaves and stems, banana plants and coconut fibers. A special type of material, nano-cellulose, is prepared from these sources a pound of which can be used to prepare a hundred pounds of reinforced plastic. The resulting material is expected to be used in manufacture of plastics used in the automobile industry.
Driving a car while sitting on a car seat made of bananas and pineapples? Why not? After all this is the wondrous world of science!
Building Materials from Green House Gas
The carbon dioxide emitted from burning of fossil fuels, particularly in industrial plants, is adding to the increasing threat of global warming. The use of scrubbers in such plants can remove the carbon dioxide but the resulting liquid must then be processed to remove the carbon dioxide from it, which is then compressed and stored. However the process is expensive and industries are reluctant to bear this additional expenditure. Now students at Michigan Technological University in USA have developed a process that captures the carbon dioxide from chimney stacks and converts it into a solid that can be used as a building material. This will allow industrialists to have a value-added by-product which they can sell and recover the investment made in the process.
Colour Changing Smart Materials
Certain fishes, reptiles, amphibians and squids have the remarkable property of changing their colours. They can make the colours of their skin light or dark, or completely change their colour according to their environment. Pulsating bands of colour can also often run across their skins, creating a fascinating picture. This is achieved by them through contraction of muscles in unison that in turn affect certain special cells ("chromatophores"). These cells contain granules of pigments. When the cells contract, these pigment-containing cells expand, and the colour that they contain becomes the dominant visible colour. In the case of zebra fish a different mechanism is employed. They have similar cells that contain reservoirs of liquid colour. When they contract their muscles, this liquid colour runs across underneath the skin, spreading like coloured ink.
Now scientists at the University of Bristol in UK are designing smart materials that can change colour just like these fishes and reptiles. They have used soft stretchable electrically activated polymers ("dielectric elastomers") to achieve the same effects. On application of an electric current, the elastomeric materials can expand, and create affects of changing colours, just like the expansion of the pigment-containing sacs in reptiles and fishes. By controlling the pigments and electrical currents, various shades of fabrics made from these materials can be created.
So in tomorrow's parties, you may be able to change the colour of your shirt by pressing a button!
Electricity Generating Carbon Sheets
Graphene comprises one-atom thick sheets of carbon atoms in which the atoms are arranged in hexagonal honeycomb patterns. It is the thinnest and strongest material known with excellent heat and electricity conducting properties. Andre Geim and Konstantin Novoselov at the University of Manchester were awarded the Nobel Prize in Physics for 2010 for their groundbreaking experiments on graphene. It has already found wide applications ranging from corrosion coatings to transistors and super-capacitors.
Now Reed and Mitchell Ong working at Stanford University have shown that graphene can actually generate electricity if it is subjected to mechanical stress. It can also change shape when an electric current is passed through it (i.e. it can behave as a “piezoelectric” material). This property was incorporated by introducing atoms of different elements such as hydrogen, lithium, potassium and fluorine on one the flat carbon sheets.
This opens up a host of new applications in the field of acoustics, photonics, electronics and energy harvesting devices.
Exciting Advances in Wonder Material Manufacture: Graphene
Have you seen a bee hive - how it is made of hexagons fused together, with little compartments, inside which bees store food and live. Now think of an ultra-thin flat sheet having a similar shape of fused six-membered rings made of carbon. An exciting new materials developed in recent years, “graphene”, comprises such a honeycomb structure of single carbon atoms. Graphene was discovered in 2004 by Andre Geim and Konstantin Novoselov who were awarded the Nobel Prize in Physics for 2010 for this work. The material is beginning to find wide applications in transistors, capacitors, batteries and computer chips. The layers of graphene are so thin that if 3 million sheets are stacked one on top of the other, they would have a thickness of only one millimeter! Graphene is usually prepared by vapor deposition but in order to make the best performing material, a challenge is to obtain uniform thickness. Now a team of scientists led by Ivan Vlassiouk at the U.S. Department of Energy's Oak Ridge National Laboratory, and Sergei Smirnov at New Mexico State University have developed a new approach involving the use of hydrogen gas in the vapor deposition process. The result was the formation of sheets of graphene of uniform thickness which could be used for production of high quality electronic components.
The discoverers of graphene at the University of Manchester, Madrid and Moscow reported in July 2011 that electron-electron interactions with graphene, can considerably enhance the velocities of the electrons. This opens up a whole new world of electronics and can lead to the development of ultra-fast transistors and super detectors.
Gold Coated Fibres – for Gold Fabrics
A Swiss company has developed a plasma coating machine that can put a fine layer of gold on silk thread. A piece of gold is bombarded with a stream of fast moving ions of argon. This results in atoms of gold being dislodged from the metal and these are then coated on a thread of silk passing slowly nearby in the machine. This gold coated silk can then be used to weave beautiful silk ties. The plasma coating process of the silk thread is such that the gold does not come off during subsequent washing. There is however one snag - the cost of the fabric made from it. Each tie will carry 8 grams of gold and will be marketed at a price of about $8,500!
New Mosquito Resistant Clothing
According to WHO, some 200 million people suffer from malaria each year. It caused about 655,000 deaths in 2010, though the actual number may be much higher as many deaths are often unrecorded. Children below the age of five are the most vulnerable. Most of the cases of severe disease are caused by the mosquito Plasmodium falciparum, though four other mosquito species are also known to cause milder forms of malaria. The disease is widespread in sub-Saharan Africa, Asia and the Americas, particularly in the tropical and subtropical regions near the equator where high humidity, warm temperatures, constant rainfall and stagnant waters provide ideal breeding grounds for mosquito larvae. The development of resistance to most drugs has further aggravated the problem. A number of sprays and lotions have been developed that repel mosquitoes and mosquito repellent bed nets are commonly used.
Now a company in Portugal, "Nanolabel", has invented a new treatment for clothing that it claims to be much superior to existing repellents. The process involves the use of nanotechnology. Clothes are impregnated with amorphous silica (sand) nanoparticles that have a chemical repellent embedded within their core. The exact nature of this repellent is being kept a closely guarded secret. The work was carried out at the Institute of Hygiene and Tropical Medicine in Lisbon.
Next Generation Robotic Suits
US soldiers now have access to special suits that give them super-human strength and speed. This is the result of a decade long effort by a US Defense agency, DARPA, that funded a $ 50 million project about a decade ago. The project, entitled "Exoskeletons for Human Performance Augmentation" was designed to develop various types of exoskeletons that could be worn by soldiers in order to give them strength and speed as well as allow them to carry large quantities of arms and ammunitions and other heavy objects for long periods of time without tiring. The Wearable Energetically Autonomous Robot (WEAR) from SARCOS Research Corporation was one of the successful products resulting from this research. The suits will now be powered using fuel cells that will add to their utility.
Another interesting development has been the Springtail Exoskeleton Flying Vehicle, built by Trek Aerospace. This has a range of 125 miles, a cruising speed of 70 knots and the ability to hover dead still at altitudes of up to 8000 meters. These flying suits, that can be worn individually by soldiers and allow them to fly to battle, are under development by Trek Aerospace with funding from the US defense agency, DARPA.
No More Flat Tires
At the Tokyo Motor Show in Japan held recently, Bridgestone displayed novel tires that are solid and consequently cannot develop a puncture. The 9 inch wheels have no air in them but have thermoplastic-resin spokes that extend from the rim to the tread. The material from which the tires are made can be recycled. Earlier in 2006 the French company had developed its “Tweel” technology that was used to make airless tires. Later Resilient Technologies LLC based in Wisconsin was funded under a Department of Defense (USA) contract to develop tires that could not be punctured. The US army was interested because its heavy military vehicles, such as Humvees, could be immobilized in the battlefield by explosive devices. The company developed a tire with a honeycomb internal structure that could not be punctured. Now Bridgestone too has entered the fray!
Reusable Sticking Tape – learning from Lizards
Have you seen how insects and lizards can climb up walls as well as slither on the roof of your room upside down without falling off. What gives them this remarkable ability? They have thousands of tiny hairs (“setae”) on their feet and legs. As these large number of hairs simultaneously touch the surface of the wall or the roof, the additive effect of the weak attractive forces (Van der Waal’s attractions) create a significant sticking force that allows these insects and lizards to climb up vertical walls or travel upside down on the bottom of a roof with ease.
Now scientists at the Zoological Institute at the University of Kiel in Germany have developed a new type of adhesive learning from these gravity defying lizards and insects. The new silicone tape invented by them has a large number of tiny hairs on its surface, just as on the legs and feet of insects and lizards. The new tape does not use any kind of sticking glue, but it sticks far more strongly than standard adhesives. It can be reused thousands of times, and it also sticks strongly when used under water.
Could mobile telephones or other electronic devices be made of paper or fabrics? A new recent discovery has made this possible. Scientists at the North Carolina University in USA have found that it is possible to deposit conductive nanocoatings on paper or textiles. Such materials can then be used in all sorts of electronic devices. The coatings are thousands of times thinner than a human hair, and are made up of the same inorganic materials that are used in electronic sensors, solar cells and microelectronics. They can be coated on paper, woven cotton or on non-woven polypropylene materials that are commonly used for making grocery bags.
This is opening up new possibilities to manufacture “communication clothing” and smart fabrics are being developed. Thus researchers at Iowa State University have used photovoltaic textiles to develop a tie made of solar cells that will charge a mobile phone. Similarly Bluetooth iJackets have been developed by a company, Zegna Sport. It will allow the wearer of the jacket to listen to an iPod and use a cell phone simultaneously through a controller embedded in the sleeve. Such intelligent clothing is strong, water proof and smart.
Super Hard Form of Carbon Discovered
We are all familiar with carbon. Coal is a common form, as is graphite. Ladies often swoon over diamonds which is a crystalline and the hardest form of carbon known. Another exciting form of carbon, graphene, was discovered in 2004. Its two dimensional layer of carbons is revolutionising the electronics industry, and is beginning to find use in flexible touch displays, lighter aircraft, cheaper batteries and small and fast electronic devices. Scientists have now been able to make a new super hard form of carbon that can stand extreme stresses. This was previously possible only with diamonds, (as is evident from the glass cutting pens that have a diamond tip, and can easily cut glass without being affected themselves). Diamonds also find many industrial uses because of their hardness and other properties.
The new form of super hard carbon was prepared by scientists at Stanford university and the Carnegie Institute of Science. They took “glassy carbon” and exposed it to very high pressures. Glassy carbon has been known for the last 60 years - it combined the properties of glass with ceramics and graphite (high temperature resistance, hardness, low density etc.). The new form of super hard carbon is amorphous (in contrast to diamonds that are crystalline). The strength of diamonds depends on the direction in which the crystals grow. The new form of hard carbon may therefore have significant advantages over diamonds as it will have strength in all directions. The super hard nature of the new material is likely to lead to a host of new materials with applications in industry.
A new thermoelectric material, named "Power Felt" was created by a team of researchers at North Carolina's Wake Forest University. The material has the amazing property to utilise the temperature difference between the inner side of the fabric and its outer surface. The inner surface is warmer because it is heated by body heat, while its exterior surface is cooled by the wind. This temperature difference is utilised to produce electricity. The novel fabric can be used for a number of devices that need power to operate. A mobile phone cover could keep the phone permanently being provided with power without connecting it into an electrical socket. It could also be used to have housings made of it that can power flash lights. It could even be used to power electrical devices in your car if your warm butt is covered with it! Efforts are under way to make a thinner fabric using carbon nanotube technology.
Undetectable to Eyes – Now to Ears
An exciting new branch of science, “metamaterials”, has evolved rapidly in the last few years. These materials have the remarkable ability to bend light around them, so that objects coated with them are invisible to the naked eye as well as to infrared and other viewing devices. The persons looking at such objects can therefore see only what lies behind such objects. Scientists at Germany's Karlsruhe Institute of Technology have now succeeded in using the same principles for developing regions from which sounds cannot be detected - cones of silence.
The “invisibility cloaks” being developed will help in providing camouflage to tanks, airplanes and submarines. Research in this area is therefore being intensively funded by US and other defense agencies.
There have been exciting developments in the field of new materials. Intelligent materials have been developed that remember their shapes and revert to them when distorted. Nano-cellulose has been found to be bullet proof, and may be employed in making bullet proof jackets.