Posts about materials engineering

Battery Breakthrough Using Organic Storage

Battery offers renewable energy breakthrough

a metal-free flow battery that relies on the electrochemistry of naturally abundant, inexpensive, small organic (carbon-based) molecules called quinones, which are similar to molecules that store energy in plants and animals.

The mismatch between the availability of intermittent wind or sunshine and the variable demand is the biggest obstacle to using renewable sources for a large fraction of our electricity. A cost-effective means of storing large amounts of electrical energy could solve this problem.

Flow batteries store energy in chemical fluids contained in external tanks, as with fuel cells, instead of within the battery container itself. The two main components — the electrochemical conversion hardware through which the fluids are flowed (which sets the peak power capacity) and the chemical storage tanks (which set the energy capacity) — may be independently sized. Thus the amount of energy that can be stored is limited only by the size of the tanks. The design permits larger amounts of energy to be stored at lower cost than with traditional batteries.

This looks like a very interesting field of research. Storing power remains one of the challenges for renewable energy sources such as solar and wind. This is especially true if the use is disconnected from the grid, but is even true for grid-connected uses. Especially as increasing the amount of wind and solar energy make it increasingly likely that surplus energy is created at certain times.

The research seems to allow for sensible size home storage setups. At the commercial level the volume needed is very large. Another concern to be addressed is how many cycles the “battery” is good for before it degrades; current experimentation show no degradation after 100 cycles but consumer/commercial usage will need thousands of cycles.

Related: Battery Breakthrough (solid sodium metal mated to a sulphur compound by an extraordinary, paper-thin ceramic membrane)Energy Storage Using Carbon Nanotubes (2006)Chart of Wind Power Generation Capacity Globally 2005-2012Recharge Batteries in Seconds

3d Printers Can Already Save Consumers Money

I first wrote about 3d printing at home here, on the Curious Cat Engineering blog, in 2007. Revolutionary technology normally takes quite a while to actually gain mainstream viability. I am impressed how quickly 3d printing has moved and am getting more convinced we are underestimating the impact. The quality of the printing is improving amazingly quickly.

3d printed objects

As is so often the case these day, our broken patent system is delaying innovation in our society. For 3d printing there is a good argument the delays due to the innovation crippling way that system is operating today will be avoided as critical 3d patents expire in 2014. Patents can aid society but the current system is not, instead it is causing society great harm and delaying us being able to use new innovations.

“For the average American consumer, 3D printing is ready for showtime,” said Associate Professor Joshua Pearce, Michigan Technological University.

3D printers deposit multiple layers of plastic or other materials to make almost anything, from toys to tools to kitchen gadgets. Free designs that direct the printers are available by the tens of thousands on websites like Thingiverse (a wonderful site). Visitors can download designs to make their own products using open-source 3D printers, like the RepRap, which you build yourself from printed parts, or those that come in a box ready to print, from companies like Type-A Machines.

3D printers have been the purview of a relative few aficionados, but that is changing fast, Pearce said. The reason is financial: the typical family can already save a great deal of money by making things with a 3D printer instead of buying them off the shelf.

In the study, Pearce and his team chose 20 common household items listed on Thingiverse. Then they used Google Shopping to determine the maximum and minimum cost of buying those 20 items online, shipping charges not included.

Next, they calculated the cost of making them with 3D printers. The conclusion: it would cost the typical consumer from $312 to $1,944 to buy those 20 things compared to $18 to make them in a weekend.

Open-source 3D printers for home use have price tags ranging from about $350 to $2,000. Making the very conservative assumption a family would only make 20 items a year, Pearce’s group calculated that the printers would pay for themselves quickly, in a few months to a few years.

The group chose relatively inexpensive items for their study: cellphone accessories, a garlic press, a showerhead, a spoon holder, and the like. 3D printers can save consumers even more money on high-end items like customized orthotics and photographic equipment.

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Research on Ancient Roman Concrete Will Allow the Creation of More Durable and Environmentally Friendly Concrete

Analysis of samples of ancient Roman concrete pinpointed why the best Roman concrete was superior to most modern concrete in durability, why its manufacture was less environmentally damaging – and how these improvements could be adopted in the modern world.

“It’s not that modern concrete isn’t good – it’s so good we use 19 billion tons of it a year,” says Paulo Monteiro (U.S. Department of Energy’s Lawrence Berkeley National Laboratory). “The problem is that manufacturing Portland cement accounts for seven percent of the carbon dioxide that industry puts into the air.”

Portland cement is the source of the “glue” that holds most modern concrete together. But making it releases carbon from burning fuel, needed to heat a mix of limestone and clays to 1,450 degrees Celsius (2,642 degrees Fahrenheit) – and from the heated limestone (calcium carbonate) itself. Monteiro’s team found that the Romans, by contrast, used much less lime and made it from limestone baked at 900˚ C, or lower, requiring far less fuel than Portland cement.

Cutting greenhouse gas emissions is one powerful incentive for finding a better way to provide the concrete the world needs; another is the need for stronger, longer-lasting buildings, bridges, and other structures. Roman harbor installations have survived 2,000 years of chemical attack and wave action underwater. We now expect our construction to last 50 to 100 years.

The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated – incorporating water molecules into its structure – and reacted with the ash to cement the whole mixture together.

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Graphene: Engineered Carbon

A material for all seasons

Graphene, a form of the element carbon that is just a single atom thick, had been identified as a theoretical possibility as early as 1947.

Its unique electrical characteristics could make graphene the successor to silicon in a whole new generation of microchips, surmounting basic physical constraints limiting the further development of ever-smaller, ever-faster silicon chips.

But that’s only one of the material’s potential applications. Because of its single-atom thickness, pure graphene is transparent, and can be used to make transparent electrodes for light-based applications such as light-emitting diodes (LEDs) or improved solar cells.

Graphene could also substitute for copper to make the electrical connections between computer chips and other electronic devices, providing much lower resistance and thus generating less heat. And it also has potential uses in quantum-based electronic devices that could enable a new generation of computation and processing.

“The field is really in its infancy,” says Michael Strano, associate professor of chemical engineering who has been investigating the chemical properties of graphene. “I don’t think there’s any other material like this.”

The mobility of electrons in graphene — a measure of how easily electrons can flow within it — is by far the highest of any known material. So is its strength, which is, pound for pound, 200 times that of steel. Yet like its cousin diamond, it is a remarkably simple material, composed of nothing but carbon atoms arranged in a simple, regular pattern.

“It’s the most extreme material you can think of,” says Palacios. “For many years, people thought it was an impossible material that couldn’t exist in nature, but people have been studying it from a theoretical point of view for more than 60 years.”

Related: Very Cool Wearable Computing Gadget from MITNanotechnology Breakthroughs for Computer ChipsCost Efficient Solar Dish by MIT StudentsSuperconducting Surprise

Nanoparticles With Scorpion Venom Slow Cancer Spread

scorpion_venomIn a, chlorotoxin molecules, colored blue and green, attach themselves to a central nanoparticle. In b, each nanoprobe offers many chlorotoxin molecules that can simultaneously latch on to many MMP-2s, depicted here in yellow, which are thought to help tumor cells travel through the body. In c, over time nanoprobes draw more and more of the MMP-2 surface proteins into the cell, slowing the tumor’s spread. Image from the University of Washington.

University of Washington researchers found they could cut the spread of cancerous cells by 98 percent, compared to 45 percent for the scorpion venom alone, by combining nanoparticles with a scorpion venom compound already being investigated for treating brain cancer.

For more than a decade scientists have looked at using chlorotoxin, a small peptide isolated from scorpion venom, to target and treat cancer cells. Chlorotoxin binds to a surface protein overexpressed by many types of tumors, including brain cancer. Previous research by Miqin Zhang‘s group combined chlorotoxin with nanometer-scale particles of iron oxide, which fluoresce at that size, for both magnetic resonance and optical imaging.

Chlorotoxin also disrupts the spread of invasive tumors — specifically, it slows cell invasion, the ability of the cancerous cell to penetrate the protective matrix surrounding the cell and travel to a different area of the body to start a new cancer. The MMP-2 on the cell’s surface, which is the binding site for chlorotoxin, is hyperactive in highly invasive tumors such as brain cancer. Researchers believe MMP-2 helps the cancerous cell break through the protective matrix to invade new regions of the body. But when chlorotoxin binds to MMP-2, both get drawn into the cancerous cell.

Research showed that the cells containing nanoparticles plus chlorotoxin were unable to elongate, whereas cells containing only nanoparticles or only chlorotoxin could stretch out. This suggests that the nanoparticle-plus-chlorotoxin disabled the machinery on the cell’s surface that allows cells to change shape, yet another step required for a tumor cell to slip through the body.

So far most cancer research has combined nanoparticles either with chemotherapy that kills cancer cells, or therapy seeking to disrupt the genetic activity of a cancerous cell. This is the first time that nanoparticles have been combined with a therapy that physically stops cancer’s spread.

Full press release

Related: Using Bacteria to Carry Nanoparticles Into CellsGlobal Cancer Deaths to Double by 2030Nanoengineers Use Tiny Diamonds for Drug Delivery

Using Virus to Build Batteries

MIT researchers have shown they can genetically engineer viruses to build both the positively and negatively charged ends of a lithium-ion battery. We have posted about similar things previously, for example: Virus-Assembled BatteriesUsing Viruses to Construct Electrodes and Biological Molecular Motors. New virus-built battery could power cars, electronic devices

Gerbrand Ceder of materials science and Associate Professor Michael Strano of chemical engineering, genetically engineered viruses that first coat themselves with iron phosphate, then grab hold of carbon nanotubes to create a network of highly conductive material.

Because the viruses recognize and bind specifically to certain materials (carbon nanotubes in this case), each iron phosphate nanowire can be electrically “wired” to conducting carbon nanotube networks. Electrons can travel along the carbon nanotube networks, percolating throughout the electrodes to the iron phosphate and transferring energy in a very short time. The viruses are a common bacteriophage, which infect bacteria but are harmless to humans.

The team found that incorporating carbon nanotubes increases the cathode’s conductivity without adding too much weight to the battery. In lab tests, batteries with the new cathode material could be charged and discharged at least 100 times without losing any capacitance. That is fewer charge cycles than currently available lithium-ion batteries, but “we expect them to be able to go much longer,” Belcher said.

This is another great example of university research attempting to find potentially valuable solutions to societies needs. See other posts on using virus for productive purposes.

Invisibility Cloak Closer

Invisibility shields one step closer with new metamaterials that bend light backwards

Applications for a metamaterial entail altering how light normally behaves. In the case of invisibility cloaks or shields, the material would need to curve light waves completely around the object like a river flowing around a rock. For optical microscopes to discern individual, living viruses or DNA molecules, the resolution of the microscope must be smaller than the wavelength of light.

The common thread in such metamaterials is negative refraction. In contrast, all materials found in nature have a positive refractive index, a measure of how much electromagnetic waves are bent when moving from one medium to another.

In a classic illustration of how refraction works, the submerged part of a pole inserted into water will appear as if it is bent up towards the water’s surface. If water exhibited negative refraction, the submerged portion of the pole would instead appear to jut out from the water’s surface.

For a metamaterial to achieve negative refraction, its structural array must be smaller than the electromagnetic wavelength being used. Not surprisingly, there has been more success in manipulating wavelengths in the longer microwave band, which can measure 1 millimeter up to 30 centimeters long.

Related: Engineering Harry Potter’s Invisibility CloakUC-Berkeley Course Videos now on YouTubeposts on university based researchBerkeley tagged posts

Squid Materials Engineering

Scientists find that squid beak is both hard and soft

The sharp beak of the Humboldt squid is one of the hardest and stiffest organic materials known. Engineers, biologists, and marine scientists at the University of California, Santa Barbara, have joined forces to discover how the soft, gelatinous squid can operate its knife-like beak without tearing itself to pieces.

The key to the squid beak lies in the gradations of stiffness. The tip is extremely stiff, yet the base is 100 times more compliant, allowing it to blend with surrounding tissue. However, this only works when the base of the beak is wet. After it dries out, the base becomes similarly stiff as the already desiccated beak tip.

“You can imagine the problems you’d encounter if you attached a knife blade to a block of Jell-o and tried to use that blade for cutting. The blade would cut through the Jell-o at least as much as the targeted object. In the case of the squid beak, nature takes care of the problem by changing the beak composition progressively, rather than abruptly, so that its tip can pierce prey without harming the squid in the process. It’s a truly fascinating design!”

“If we could reproduce the property gradients that we find in squid beak, it would open new possibilities for joining materials,” explained Zok. “For example, if you graded an adhesive to make its properties match one material on one side and the other material on the other side, you could potentially form a much more robust bond,” he said. “This could really revolutionize the way engineers think about attaching materials together.”

Related: Deep-Sea Giant SquidSelf Healing PlasticSea Slug Photo Gallery

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