materialsscienceandengineering: ‘Meta-Skin’ Truly Cloaks...

materialsscienceandengineering:

‘Meta-Skin’ Truly Cloaks Objects From Radar

It’s a bird, it’s a plane, it’s…wait, I don’t see anything there. Stealth aircraft could get even harder to detect with a new flexible, stretchy metamaterial that effectively traps and suppresses radar waves.

The cloaking tech has potential military applications, including coating next-generation stealth bombers.

A team at Iowa State University led by electrical and computer engineering professor Jiming Song and associate professor Liang Dong developed a metamaterial they’re calling “meta-skin.”

Metamaterials are manmade materials that have capabilities greater than the sum of their individual components. While cartoonist Randall Munroe sadly doesn’t have an entry for them in his “Thing Explainer” book, his xkcd comic strip does. Having learned about the physical feats some can pull off, I think they’re kind of magical.

The engineers at Iowa State University created their metamaterial by embedding rows of tiny split-ring resonators inside silicone sheets. These resonators contain the liquid metal alloy galinstan, which is gallium, indium, and tin. It’s used commercially and has low toxicity compared to other liquid metals. I even found some on Amazon.com.

Read more.

Looks really cool.

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teachersource: When you put this thick piece of black paper on...

teachersource:

When you put this thick piece of black paper on a cup of hot liquid, it turns brilliant colors. The secret is the liquid crystals inside the paper. Different temperatures cause the molecules to arrange themselves in different ways, which will reflect light in ways we know as colors. See our website for a full explanation of the science!

I need to do a materials presentation, and I’m thinking liquid crystals would be an awesome topic…

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materialsscienceandengineering: Liquid Crystals: Intermediate...

materialsscienceandengineering:

Liquid Crystals: Intermediate phases of matter

The term liquid crystals may sound like an oxymoron, given that liquid matter consists of unaligned atoms or molecules in constant random motion while crystals are defined as solids whose atoms or molecules are arranged in a highly ordered microscopic structure, but this unique phase of matter is very real and quite relevant. Neither true liquids or crystals, liquid crystal phases of matter have many of the physical attributes of liquids but with a certain degree of order to its constituent molecules.

Liquid crystals were discovered in 1888 by an Austrian botanical physiologist who discovered that his cholesterol derivative appeared to have two melting points, first turning into a cloudy liquid at 145° C and then a transparent one at 178° C.  However, it wasn’t until many decades later that scientists truly began to study liquid crystals with interest, including one French physicist Pierre-Gilles de Gennes who would eventually receive a Nobel Prize for his work.

Generally cloudy in appearance, liquid crystals exist in a variety of phases of their own (called mesophases). Two of these such phases are shown above, compared with conventional solid and liquid matter. The nematic (meaning thread like) phase of a liquid crystal consists of molecules all aligned in the same direction even as they are capable of drifting around as in any other liquid. The smectic (meaning soap like) phase consists of molecules arranged in layers that can slip over each other. Other liquid crystal phases include chiral phases, discotic phases, and bowlic phases. 

The most common and perhaps well known use of liquid crystals is in liquid crystal displays, or LCDs, which rely on the changing optical properties of liquid crystals around electric fields.

Sources: ( 1 - images 2 + 3 ) ( 2 - image 1 ) ( 3 )

So important, but so weird.

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materialsscienceandengineering: New material lights up when...

materialsscienceandengineering:

New material lights up when detecting explosives

Scientists have created a material which turns fluorescent if there are molecules from explosives in the vicinity. The discovery could improve, for example, airport security – and also it gives us an insight into a rather chaotic micro-world where molecules and atoms constantly are responding to their surroundings.

Unlike humans, dogs’ noses are so sensitive that they can smell explosives in the vicinity. They can detect single molecules in the air, and thus they may be valuable helpers when it comes to detecting explosives.

Inspired by such talents, science is devoting many resources on developing electronic or chemical “noses” which similarly can detect explosives molecules and thus warn that explosives may be hiding in the vicinity.

Researchers from University of Southern Denmark now report the creation of a new material, consisting of a set of molecules which react when encountering explosives molecules in their vicinity. The set consists of the molecules TTF-C[4]P and TNDCF.

TNDCF has the special talent that it becomes fluorescent when an explosives molecule is introduced to the set of molecules.

Read more.

This is cool and pretty useful.

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materialsscienceandengineering: Nano-coating makes coaxial...

materialsscienceandengineering:

Nano-coating makes coaxial cables lighter

Scientists replace metal with carbon nanotubes for aerospace use

Common coaxial cables could be made 50 percent lighter with a new nanotube-based outer conductor developed by Rice University scientists.

The Rice lab of Professor Matteo Pasquali has developed a coating that could replace the tin-coated copper braid that transmits the signal and shields the cable from electromagnetic interference. The metal braid is the heaviest component in modern coaxial data cables.

The research appears this month in the American Chemical Society journalACS Applied Materials and Interfaces.

Replacing the outer conductor with Rice’s flexible, high-performance coating would benefit airplanes and spacecraft, in which the weight and strength of data-carrying cables are significant factors in performance.

Rice research scientist Francesca Mirri, lead author of the paper, made three versions of the new cable by varying the carbon-nanotube thickness of the coating. She found that the thickest, about 90 microns – approximately the width of the average human hair – met military-grade standards for shielding and was also the most robust; it handled 10,000 bending cycles with no detrimental effect on the cable performance.

Read more.

Why are we still using co-ax cables?

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archenland: Buckminsterfullerene Also called buckyball, it is a...

archenland:

Buckminsterfullerene

Also called buckyball, it is a spherical fullerene molecule with the formula C₆₀. It has a cage-like fused-ring structure (truncated icosahedron) which resembles a soccer ball, made of twenty hexagons and twelve pentagons, with a carbon atom at each vertex of each polygon and a bond along each polygon edge.

The properties of buckyballs have caused researchers and companies to consider using them in several fields. 

• Buckyballs may be used to trap free radicals generated during an allergic reaction and block the inflammation that results from an allergic reaction.
  
• The antioxidant properties of buckyballs may be able to fight the deterioration of motor function due to multiple sclerosis.
  
• Combining buckyballs, nanotubes, and polymers to produce inexpensive solar cells that can be formed by simply painting a surface.
  
• Buckyballs may be used to store hydrogen, possibly as a fuel tank for fuel cell powered cars.
  
• Buckyballs may be able to reduce the growth of bacteria in pipes and membranes in water systems.
  
• Researchers are attempting to modify buckyballs to fit the section of the HIV molecule that binds to proteins, possibly inhibiting the spread of the virus.
  
• Making bullet proof vests with inorganic (tungsten disulfide) buckyballs.
  

This is such a weird structure…

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materialsscienceandengineering: Graphene composite may keep...

materialsscienceandengineering:

Graphene composite may keep wings ice-free

Conductive material heats surfaces, simplifies ice removal

A thin coating of graphene nanoribbons in epoxy developed at Rice University has proven effective at melting ice on a helicopter blade.

The coating by the Rice lab of chemist James Tour may be an effective real-time de-icer for aircraft, wind turbines, transmission lines and other surfaces exposed to winter weather, according to a new paper in the American Chemical Society journal ACS Applied Materials and Interfaces.

In tests, the lab melted centimeter-thick ice from a static helicopter rotor blade in a minus-4-degree Fahrenheit environment. When a small voltage was applied, the coating delivered electrothermal heat – called Joule heating – to the surface, which melted the ice.

The nanoribbons produced commercially by unzipping nanotubes, a process also invented at Rice, are highly conductive. Rather than trying to produce large sheets of expensive graphene, the lab determined years ago that nanoribbons in composites would interconnect and conduct electricity across the material with much lower loadings than traditionally needed.

Read more.

Let’s fly through all the blizzards!

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materialsscienceandengineering: Swedish scientists use wood to...

materialsscienceandengineering:

Swedish scientists use wood to create biodegradable, renewable alternative to Styrofoam

Maybe soon we can say goodbye to polystyrene, the petroleum-based material that is used to make Styrofoam. In what looks like an ordinary bicycle helmet, Swedish designers have replaced Styrofoam with a new shock-absorbing material made with renewable and biodegradable wood-based material.      

Researcher Lars Wågberg, a professor in Fibre Technology at Stockholm’s KTH Royal Institute of Technology, says the wood-based foam material offers comparable properties to Styrofoam.

“But even better, it is from a totally renewable resource—something that we can produce from the forest,” Wågberg says.

That’s a big plus for a country where forests are planted and harvested continuously, much like any other cash crop.

Trademarked under the name, Cellufoam, the material was developed by Wågberg together with Lennart Bergström, professor in Material Chemistry at Stockholm University, and Nicholas Tchang Cervin, a former PhD student at KTH, in theWallenberg Wood Science Center (WWSC).

Read more.

Cool.

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materialsscienceandengineering: Move aside carbon: Boron...

materialsscienceandengineering:

Move aside carbon: Boron nitride-reinforced materials are even stronger

Carbon nanotubes are legendary in their strength – at least 30 times stronger than bullet-stopping Kevlar by some estimates. When mixed with lightweight polymers such as plastics and epoxy resins, the tiny tubes reinforce the material, like the rebar in a block of concrete, promising lightweight and strong materials for airplanes, spaceships, cars and even sports equipment.

While such carbon nanotube-polymer nanocomposites have attracted enormous interest from the materials research community, a group of scientists now has evidence that a different nanotube – made from boron nitride – could offer even more strength per unit of weight. They publish their results in the journal Applied Physics Letters, from AIP Publishing.

Boron nitride, like carbon, can form single-atom-thick sheets that are rolled into cylinders to create nanotubes. By themselves boron nitride nanotubes are almost as strong as carbon nanotubes, but their real advantage in a composite material comes from the way they stick strongly to the polymer.

“The weakest link in these nanocomposites is the interface between the polymer and the nanotubes,” said Changhong Ke, an associate professor in the mechanical engineering department at the State University of New York at Binghamton. If you break a composite, the nanotubes left sticking out have clean surfaces, as opposed to having chunks of polymer still stuck to them. The clean break indicates that the connection between the tubes and the polymer fails, Ke noted.

Read more.

Brb. Redesigning our lunar robot.

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reinamunciveng: Bamboo Fibre is Stronger and Cheaper than...

reinamunciveng:

Bamboo Fibre is Stronger and Cheaper than Steel– says Dirk Hebel

Bamboo could ‘revoulutinalise the building industry’ and replace steel as the dominant reinforcing material, according to a professor working on new applications for the grass. 

Dirk Hebel is a professor at Swiss Federal Institute of Technology Zurich (ETH). He said bamboo fibre is more sustainable and is a much cheaper alternative to steel on construction sites. It has the potential to prove an alternative to monopoly of reinforced concrete. 

This material called bamboo composite material can be pressed into any shape and then sawn or sanded like wood. Whilst forming it into rod shape, it can functions just as a reinforcing matrix for concrete with no loss of performance. According to him, “we can produce a material that in terms of tensile capacity is better than steel,” and “our material is only a quarter of the weight of steel.” Apparently, bamboo fibre performs better than steel in terms of strength to weight. It could also be used in industrial applications such as in the automotive industry. 

70% of all steel and 90% of all cement is consumed in developing countries and of these, Hebel found bamboo growing in those areas. Bamboo has high tensile strenght and has actually been long used as a construction material in the developing world as its natural state.Bamboo does not require replanting after harvesting unlike timber  Hebel is suggesting to use it as a way of extracting fibres from the plant and mixing it with 10% organic resin to create mouldable material. One breakthrough happened during the testing of the concrete reinforced with bamboo at a lab in Singapore- the machine was not able to break it! 

Architecture firms like Kengo Kuma and Shigeru Ban have already started experimenting with this material and Vienna-based Penda has developed proposals for bamboo hotels and even entire modular cities made from this material. Since cement products accounts for 50% of all construction materials used globally, alternating to this material can make a huge difference. Even Berkeley University is working on the development of an alternative to concrete that is not based on cement but on a biological based material made of mycelium-material fungi is made of. 

“Can you build high-rises with that material?” he said. “In theory you can but that is not the market we’re talking. Eighty per cent of all structures worldwide are one or two stories. That is our market.”

(source)

So many pictures of material tests.

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Turning Girl Scout Cookies Into Graphene

Turning Girl Scout Cookies Into Graphene:

smilesandvials:

“What Jim Tour down in Houston discovered and showed is that anything that’s got carbon in it you can turn into graphene.

And to demonstrate that he meant anything, he did it with Girl Scout cookies. He turned those into graphene. He did it with chocolate. He got some chocolate half-dollar coins. He did it with dog feces from a miniature Dachshund, and he did it with a cockroach leg. And essentially he just got a really big oven, heated it up to about 1,000 degrees C and filled that oven with a little bit of this stuff, the cockroach or the dog feces, whatever, and a sheet of pure copper and a little bit of gas, left it for about 20 minutes, and viola, he’d made little bits of really high-quality graphene.”

Keyword here is “little bits” but this will always crack me up. 

What.

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5 things you didn’t know about…quartz

materialsscienceandengineering: Amorphous metal, metallic...

Samples of amorphous metal, with millimeter scale.


Metallic glass - shiny, easy to mould and with a high strength-to-weight ratio.


A time-temperature-transformation diagram for the primary crystallization of V1.


The relations between mechanical properties of typical BMGs.


A sample of a fractured amorphous metal alloy.

materialsscienceandengineering:

Amorphous metal, metallic glass

In nature they prefer to form crystal structures but if liquid metals are cooled down fast enough then, just like glass, the atoms will arrange into a disordered amorphous structure. These amorphous metals, also called metallic glasses, don’t exist naturally because the cooling rates required can be on the order of millions of degrees a second. Methods of forming these materials include extremely rapid cooling, physical vapor deposition, solid-state reaction, ion irradiation, and mechanical alloying.

Metallic glasses are materials of interest because of the properties that can result. They typically have extremely high strength to weight ratios (higher than aluminium and titanium alloys) and are tougher and less brittle than oxide glasses and ceramics. Like crystalline metallic alloys, the properties of these materials also depends upon the composition. Alloys of boron, silicon, phosphorus, and other glass formers with magnetic metals have high magnetic susceptibility and electrical resistance. The fact that amorphous metals are true glasses also allows for easy processing because they soften and flow upon heating. Not all properties are favorable however, metallic glasses also typically have lower ductilities and fatigue strengths. 

Bulk metallic glasses, or BMGs, are alloys with critical cooling rates low enough to allow formation of the desired amorphous structure in thick layers (over 1 millimeter). They are made from alloys with typically three to five metallic components that have a large atomic-size mismatch and a composition close to a deep eutectic. Some examples include Vitreloy 1 (41.2% Zr, 13.8% Ti, 12.5% Cu, 10% Ni, and 22.5% Be), Ti₄₀Cu₃₆Pd₁₄Zr₁₀, and Mg₆₀Zn₃₅Ca₅.

Sources: (1, top left) (2, top right) (3, middle left) (4, middle right) (5, bottom)

Not all glasses are Glass, the clear compound made from silica used in windows and such. A glass is a kind of compound.

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labphoto: A small amount of Cesium metal. Caesium or cesium is...

labphoto:

A small amount of Cesium metal. Caesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes it liquid at or near room temperature (as seen from the gif).

It is highly reactive and very pyrophoric, it ignites spontaneously in air and reacts explosively with water. Because of it’s high reactivity caesium can be stored in vacuum-sealed borosilicate glass ampoules.

Interesting fact: In 1860, Robert Bunsen and Gustav Kirchhoff discovered caesium in the mineral water from Dürkheim, Germany. Due to the bright blue lines in its emission spectrum, they chose a name derived from the Latin word caesius, meaning sky-blue. Caesium was the first element to be discovered spectroscopically, only one year after the invention of the spectroscope by Bunsen and Kirchhoff.

This is a pretty cool element.

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More Than You Ever Wanted to Know About Mechanical Engineering, Part 25: Fatigue Failure

5 things you didn’t know about…bamboo

materialsscienceandengineering: Caution: Weird material...

materialsscienceandengineering:

Caution: Weird material shrinks when warm

Most materials swell when they warm, but some do the opposite; quantum effects could explain why

Most materials swell when they warm, and shrink when they cool. But UConn physicist Jason Hancock has been investigating a substance that responds in reverse: it shrinks when it warms.

Although thermal expansion, and the cracking and warping that often result, are an everyday occurrence – in buildings, bridges, electronics, and almost anything else exposed to wide temperature swings – physicists have trouble explaining why solids behave that way.

Research by Hancock and his colleagues into scandium trifluoride, a material that has negative thermal expansion, published 1 October in Physical Review B, may lead to a better understanding of why materials change volume with temperature at all, with potential applications such as more durable electronics.

Read more.

What.

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fuckyeahfluiddynamics: Non-Newtonian fluids are capable of...

fuckyeahfluiddynamics:

Non-Newtonian fluids are capable of all kinds of counter-intuitive behaviors. The animations above demonstrate one of them: the tubeless or open siphon. Once the effect is triggered by removing some of the liquid, the fluid quickly pours itself out of the beaker. This is possible thanks to the polymers in the liquid. The falling liquid pulls on the fluid left behind in the beaker, which stretches the polymers in the fluid. When stretched, the polymers provide internal tension that opposes the extensional force being applied. This keeps the fluid in the beaker from simply detaching from the falling liquid. Instead, it flows up and over the side against the force of gravity, behaving rather more like a chain than a fluid!  (Image credit: Ewoldt Research Group, source)

This is so cool.

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zoeritts: Aerogel is the world’s lightest solid. It is also...

zoeritts:

Aerogel is the world’s lightest solid. It is also known as liquid smoke, though that seems inaccurate and overly romanticized. NASA developed it and still uses it to catch cosmic dust for study. Cool. I just learned about it from Zoe Laughlin, cofounder / director of the University College of London’s Institute of Making,

“…a multidisciplinary research club for those interested in the made world: from makers of molecules to makers of buildings, synthetic skin to spacecraft, soup to diamonds, socks to cities.” 

Actually I watched her in this mostly boring TED talk, but material science is cool and so is aerogel. 

This stuff is cool, weird, and crazy.

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Black Phosphorus Batteries

materialsscienceandengineering:

Future electronics: Black phosphorus surges ahead of graphene

Superior conductor may be mass produced for electronic and optoelectronics devices
A Korean team of scientists tune BP’s band gap to form a superior conductor, allowing for the application to be mass produced for electronic and optoelectronics devices.
The research team operating out of Pohang University of Science and Technology (POSTECH), affiliated with the Institute for Basic Science’s (IBS) Center for Artificial Low Dimensional Electronic Systems (CALDES), reported a tunable band gap in BP, effectively modifying the semiconducting material into a unique state of matter with anisotropic dispersion. This research outcome potentially allows for great flexibility in the design and optimization of electronic and optoelectronic devices like solar panels and telecommunication lasers.
To truly understand the significance of the team’s findings, it’s instrumental to understand the nature of two-dimensional (2-D) materials, and for that one must go back to 2010 when the world of 2-D materials was dominated by a simple thin sheet of carbon, a layered form of carbon atoms constructed to resemble honeycomb, called graphene. Graphene was globally heralded as a wonder-material thanks to the work of two British scientists who won the Nobel Prize for Physics for their research on it.

Read more.

Interesting. Honestly, though, whatever material or technology we use, I just want the battery breakthrough to happen soon.


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