3D printing is being used to produce more and more novel items: tools, art, even rudimentary human organs. What all those items have in common, though, is that they’re small. The next phase of 3D printing is to move on to things that are big. Really big. Like, as big as a house.
In a small town in western Russia called Stupino, a 3D printed house just went up in the middle of winter and in a day’s time.
Pieces of houses and bridges have been 3D printed in warehouses or labs then transported to their permanent locations to be assembled, but the Stupino house was printed entirely on-site by a company called Apis Cor. They used a crane-sized, mobile 3D printer and a specially-developed mortar mix and covered the whole operation with a heated tent.
The 38-square-meter (409-square-foot) house is circular, with three right-angled protrusions allowing for additional space and division of the area inside. Counter-intuitively, the house’s roof is completely flat. Russia’s not known for mild, snow-free winters. Made of welded polymer membranes and insulated with solid plates, the roof was designed to withstand heavy snow loads.
Apis Cor teamed up with partners for the house’s finishing details, like insulation, windows, and paint. Samsung even provided high-tech appliances and a TV with a concave-curved screen to match the curve of the interior wall.
According to the company, the house’s total building cost came to $10,134, or approximately $275 per square meter, which equates to about $25 per square foot. A recent estimate put the average cost of building a 2,000 square foot home in the US at about $150 per square foot.
The homes of the future?
Since these houses are affordable and fast to build, is it only a matter of time before we’re all living in 3D printed concrete circles?
Probably not—or, at least, not until whole apartment buildings can be 3D printed. The Stupino house would be harder (though not impossible) to plop down in the middle of a city than in the Russian countryside.
While cities like Dubai are aiming to build more 3D printed houses, what many have envisioned for the homes of the future are environmentally-friendly, data-integrated ‘smart buildings,’ often clad with solar panels and including floors designated for growing food.
Large-scale 3D printing does have some very practical applications, though. Take disaster relief: when a hurricane or earthquake destroys infrastructure and leaves thousands of people without shelter, 3D printers like Apis Cor’s could be used to quickly rebuild bridges, roads, and homes.
Also, given their low cost and high speed, 3D printed houses could become a practical option for subsidized housing projects.
In the US, tiny houses have been all the rage among millennials lately—what if that tiny house could be custom-printed to your specifications in less than a week, and it cost even less than you’d budgeted?
Since software and machines are doing most of the work, there’s less margin for human error—gone are the days of “the subcontractor misread the blueprint, and now we have three closets and no bathrooms!”
While houses made by robots are good news for people looking to buy a basic, low-cost house, they could be bad news for people employed in the construction industry. Machines have been pouring concrete for decades, but technologies like Apis Cor’s giant printer will take a few more human workers out of the equation.
Nonetheless, the company states that part of their mission is “to change the construction industry so that millions of people will have an opportunity to improve their living conditions.”
It sure sounds far-fetched but a story in the Beijing Times claims China is considering building a high-speed train that would connect China’s northeast with the United States. The project would cross Siberia and the Bering Strait to Alaska, and then go across Canada into the United States, according to the English-language report published in the state-run China Daily. To cross the Bering Strait into Alaska, the railway would need a 125-mile underwater tunnel, which implies it would be around four times the length of the tunnel that crosses the English Channel, notes a very skeptical Washington Post article on the report.
China Daily claims that the technology to construct such a long underwater tunnel already exists and will be used to build a tunnel to connect China’s Fujian province with Taiwan. “Right now we’re already in discussions. Russia has already been thinking about this for many years,” said a railway expert cited by the Beijing Times, according to the Independent’s report on the story. The train would reportedly travel at around 220mph, meaning the entire trip between the United States and China would take around two days.
What is being called the China-Russia-Canada-America line is one of four large-scale international high-speed rail projects the country wants to build, the Guardian writes, citing the Beijing Times:
The first is a line that would run from London via Paris, Berlin, Warsaw, Kiev and Moscow, where it would split into two routes, one of which would run to China through Kazakhstan and the other through eastern Siberia. The second line would begin in the far-western Chinese city of Urumqi and then run through Kazakhstan, Uzbekistan, Turkmenistan, Iran and Turkey to Germany. The third would begin in the south-western city of Kunming and end in Singapore.
A Chinese construction firm based in Shanghai has succeeded in building 10 houses each measuring 200 square metres in 24 hours by using an enormous 3D printer.
The houses are all eco-friendly and constructed from 3D-printed building blocks made from layers of recycled construction waste and glass fibre and mixed with cement.
Each home costs less than £3,000 to build.
WinSun Decoration Design Engineering spent 20 million Yuan (£1.9m) and 12 years to develop a 3D printer 6.6 metres tall, 10 metres wide and 150 metres long.
Large 3D printers have been in existence for several years and have been used to make plane parts and prototypes.
“We purchased parts for the printer overseas, and assembled the machine in a factory in Suzhou. Such a new type of 3D-printed structure is environment-friendly and cost-effective,” said the 3D-printer’s inventor, Winsun CEO Ma Yihe.
Winsun used architectural design software AutoCAD Architecture to not only plan the building but also to calculate tracing paths that took into account plumbing, electrical lining, insulation materials and windows, that would be added once the main structure was built.
The company holds 77 national patents for its construction materials.
Ma’s office building, which covers an area of 10,000 square metres, was also constructed with 3D-printed walls and took a month to build from an assembly line of four 3D printers.
“Industrial waste from demolished buildings is damaging our environment, but with 3D-printing, we are able to recycle construction waste and turn it into new building materials,” said Ma.
“This would create a much safer environment for construction workers and greatly reduce construction costs.”
A massive machine — longer than a football field — is munching away beneath Washington like a giant earthworm. Before it’s done, it will devour about 2 million cubic yards of soil that has been sitting under the city since the days of the dinosaurs.
It is the most amazing and expensive construction project that no one ever will see.
It will come within a center fielder’s throw of Nationals Park, within a corner kick of RFK Stadium, nibble at the deepest roots from the National Arboretum, pass below the Love Nightclub and the United House of Prayer for All, go under railroad tracks that carry 1 million-pound trains into Union Station and a six-lane roadway used by 60,000 cars a day, gnaw its way under Home Depot’s doorstep and then chomp more than a mile and a half down Rhode Island Avenue toward Logan Circle.
Like the creature from a sci-fi thriller, the machine will tunnel along — six feet at a time — beneath a city largely oblivious to its existence.
“That’s the way we like it,” said James Wonneberg, DC Water’s resident engineer.
Cars race from Italy to France through a famous tunnel under the Alps. Bullet trains rocket through a tunnel under the English Channel. One day, raw sewage will roar through Washington’s tunnel.
Not so romantic, perhaps, but vital to a city that now pumps 2 billion gallons a year from its sewers and toilets directly into the Potomac, the Anacostia and Rock Creek.
With a little help from upstream neighbors, those three tributaries may one day run closer to pure. But for now, there is only that dream and a hungry machine.
The machine itself is a marvel of technology, an underground factory 443 feet long and almost six times the weight of the Statue of Liberty. It does about a dozen things at once, and it moves.
Consider just one aspect of that movement: More than 100 feet below ground, how does it know where it’s going?
With a circular face three times the width of a Metrobus, what keeps the machine always within a few millimeters of its intended path?
Separating the streams
Washington needs this new, gargantuan 13-mile long, $2.6 billion sewer tunnel because of what might be called, in hindsight, a dumb decision. Were they still alive to defend it, the city’s forefathers might respond much like the people who were wearing bell-bottoms in the 1970s or who dye their hair electric green today: It was the fashion of the day.
The “it,” in this case, was something called a combined sewage system. They were all the rage in 19th-century America. The District has one, as do more than 770 other places where a total of 40 million people live.
That is a lot of flushes, and on a rainy day, that matters.
Here’s why: In a combined sewer system, your bath water, your laundry water and whatever you flush goes into a network of sewers that also handles all the rainwater that flows down sewer grates from the street.
On a dry day, or one with a slow but steady rain, all of that combined wastewater heads obediently to the sewage-treatment plant. In the case of the District, that is the sprawling facility called Blue Plains that sits beside the Potomac River in the southeast quadrant of the city.
But in a gully-washing downpour, a serious thunderstorm or when 10 inches of rapidly melting snow gushes down the sewer grate, the system gets unruly. The path to the treatment plant becomes overwhelmed, and a filthy mix spews from 53 different outlets into the three tributaries.
Not by accident, but by design.
It’s not an occasional thing. It happens hundreds of times a year, contributing 2 billion gallons of untreated waste to Rock Creek, the Potomac and the Anacostia, which gets the worst of it. All that unhealthy mess, of course, flows down into Chesapeake Bay on its way to the Atlantic Ocean.
“By 2032, our stated goal is to have water in the Anacostia that’s swimmable and fishable,” said George Hawkins, DC Water’s general manager.
Having the Potomac turned into an open sewer appealed to no one, and perhaps least of all to Lady Bird Johnson, who is said to have berated Lyndon about it when they flew into National Airport in daylight. That factoid has relevance even today.
Though Lyndon B. Johnson had a war and civil rights on his plate in those days, the rumblings about pollution that began on his watch led his successor, Richard M. Nixon, to create the Environmental Protection Agency in 1970.
Fast-forward 35 years. Everybody agreed that something had to be done about combined sewer systems, and the EPA and U.S. Justice Department ordered Washington and several other cities — including New York, Philadelphia and Seattle — to stop dumping combined sewer overflow into rivers.
That gave birth to the District’s tunnel plan, and last year, the massive machine began to dig.
They named it “Lady Bird.”
Underground action
Lady Bird keeps busy, at once softening the soil in its path, lurching forward to gnaw at it, sliding the stones that will be the tunnel’s wall into place, blasting fresh surface air to the work crew, laying railroad track for the cars that carry the stone, turning the dirt into muck and dumping it on a conveyor belt headed for the tunnel mouth.
The muck will fill 205,820 huge dump trucks before the project is completed in 2025.
Though all of that is going on pretty much at once — 24 hours a day, six days a week — here’s how each facet takes place.
The round face of the machine is 26 feet across and studded with tungsten carbide scraper bits and cutting wheels. Before the device shoulders forward, a barrage of chemical mix shoots from nozzles to loosen up the earth ahead.
Then the machine heaves forward by six feet, its circular face rotating as the bits and wheels slash into the soil. What they dislodge is sucked into the machine, mixed with a compound that turns it to the consistency of toothpaste and is plopped blob by blob onto a conveyor belt that runs along the ceiling to the tunnel end.
While this is underway, massive curved slabs of concrete — they call them “stones” — have arrived on a small rail car that trundles back and forth from the tunnel mouth. They are stacked in the order in which they will be put in place. When they arrive, an electric device that looks like something you might see in an automatic carwash swoops down from above, presses its big rubber gasket against the stone’s face and literally sucks it up.
Stone in hand, the machine then rumbles to the leading edge of the tunnel, where a crew of five in hard hats uses levels and laser guidance to ease each piece into place. The slabs are connected in front and back by big plastic dowels and on top and bottom by arms that are driven into place by a worker with a compressor-fired rivet gun.
Once the precise placement is achieved, the suction machine scoots back to get the next slab until the six-foot, 80,000-pound ring is complete.
But there’s more.
The machine’s boring face is 26 feet across. The interior tunnel walls are 23 feet in diameter. The stones are 14 inches thick. There is, by design, a gap between the new tunnel exterior and the hole that Lady Bird has created.
Into the gap oozes an epoxy-like substance that will harden into a six-inch-thick casing to become the tunnel’s outer defense.
As Lady Bird rides forward through the tunnel on wheels, it lays track in its wake for the rail car that feeds stones to the growing tunnel.
Now it is time for the next push. Eighteen four-ton jacks powered by the 13.8 kilovolts of electricity nudge up against the edges of the tunnel ring that has just been set in place.
Before they fire, the operator who sits in a narrow booth watching six computer monitors studies one that shows crosshairs. Using a target fixed just behind the face of the machine, and a second target behind the machine that provides global coordinates, the operator uses a laser to line up Lady Bird’s next chomp.
“Right now, he’s within an inch of being right on the mark,” said Brett R. Zernich, construction manager, pointing to the crosshairs earlier this month.
At the push of a button, the operator sends Lady Bird surging six feet farther into the soggy soil.
Chewing down the Potomac
Lady Bird said goodbye to daylight several months ago and was lowered into a deep hole on the grounds of the Blue Plains treatment plant. Right now, the machine has chewed its way more than a quarter of a mile and is about 70 feet beneath the floor of the Potomac, skirting around the Naval Research Laboratory because the Navy wasn’t keen on having a tunnel under its testing facility.
In a few months, it will curve to the right, penetrate some rocky soil and pass under Anacostia to connect with a sewage pumping station at Poplar Point. Then it will dip under the river by the same name and make its way to another pumping station near Nationals Park.
A new tunnel will begin at the Poplar Point pumping station, cross under the river just north of the 11th Street Bridge and head toward RFK Stadium. It will pass the arboretum and make a sharp left 120 feet under Rhode Island Avenue.
Just as a river has its tributaries, so does the tunnel, with the largest going up First Street from Rhode Island. And it will have diversion chambers where waste can be stored temporarily so the system isn’t overwhelmed.
All that, for $2.6 billion. Where does the money come from?
Customers. Finding a way to pay to restore other decrepit infrastructure — notably roads and bridges — has become a knotty issue, but water utilities send out monthly bills. Although DC Water services wholesale customers in Maryland and Virginia, most of the burden will fall on their customers in the District.
The average water and sewer bill has gone up by more than 50 percent in recent years, to more than $65 a month for a single-family home.
“Our ratepayers are paying for all this,” Hawkins said. “We estimate [there will be] rate increases for the next 10 years, and maybe for 20, and most of that’s for the tunnel.”
Parts of it will begin opening in 2016, with big sections to follow in 2018 and 2022. With steel filaments embedded in its concrete walls, the tunnel should last for 100 years, they say.
“I want our ratepayers to understand that we have to do this, but it’s more important that they recognize the benefits of it,” Hawkins said. “No one will ever see this tunnel, but they’ll see that the river’s cleaner, and down stream in the Chesapeake, it will be a significant difference.”
A team from UCLA has developed a new transparent solar cell that has the ability to generate electricity while still allowing people to see outside. In short, they’ve created a solar power-generating window! Described as “a new kind of polymer solar cell (PSC)” that produces energy by absorbing mainly infrared light instead of traditional visible light, the photoactive plastic cell is nearly 70% transparent to the human eye—so you can look through it like a traditional window.
“These results open the potential for visibly transparent polymer solar cells as add-on components of portable electronics, smart windows and building-integrated photovoltaics and in other applications,” said study leader Yang Yang, a UCLA professor of materials science and engineering and also director of the Nano Renewable Energy Center at California NanoSystems Institute (CNSI). “Our new PSCs are made from plastic-like materials and are lightweight and flexible. More importantly, they can be produced in high volume at low cost.”
There are also other advantages to polymer solar cells over more traditional solar cell technologies, such as building-integrated photovoltaics and integrated PV chargers for portable electronics. In the past, visibly transparent or semitransparent PSCs have suffered low visible light transparency and/or low device efficiency because suitable polymeric PV materials and efficient transparent conductors were not well deployed in device design and fabrication. However that was something the UCLA team wished to address.
By using high-performance, solution-processed, visibly transparent polymer solar cells and incorporating near-infrared light-sensitive polymer and silver nanowire composite films as the top transparent electrode, the UCLA team found that the near-infrared photoactive polymer absorbed more near-infrared light but was less sensitive to visible light. This, in essence, created a perfect balance between solar cell performance and transparency in the visible wavelength region.
The first bionic hand that allows an amputee to feel what they are touching will be transplanted later this year in a pioneering operation that could introduce a new generation of artificial limbs with sensory perception.
The patient is an unnamed man in his 20s living in Rome who lost the lower part of his arm following an accident, said Silvestro Micera of the Ecole Polytechnique Federale de Lausanne in Switzerland.
The wiring of his new bionic hand will be connected to the patient’s nervous system with the hope that the man will be able to control the movements of the hand as well as receiving touch signals from the hand’s skin sensors.
Dr Micera said that the hand will be attached directly to the patient’s nervous system via electrodes clipped onto two of the arm’s main nerves, the median and the ulnar nerves.
This should allow the man to control the hand by his thoughts, as well as receiving sensory signals to his brain from the hand’s sensors. It will effectively provide a fast, bidirectional flow of information between the man’s nervous system and the prosthetic hand.
“This is real progress, real hope for amputees. It will be the first prosthetic that will provide real-time sensory feedback for grasping,” Dr Micera said.
“It is clear that the more sensory feeling an amputee has, the more likely you will get full acceptance of that limb,” he told the American Association for the Advancement of Science meeting in Boston.
“We could be on the cusp of providing new and more effective clinical solutions to amputees in the next year,” he said.
An earlier, portable model of the hand was temporarily attached to Pierpaolo Petruzziello in 2009, who lost half his arm in a car accident. He was able to move the bionic hand’s fingers, clench them into a fist and hold objects. He said that he could feel the sensation of needles pricked into the hand’s palm.
However, this earlier version of the hand had only two sensory zones whereas the latest prototype will send sensory signals back from all the fingertips, as well as the palm and the wrists to give a near life-like feeling in the limb, Dr Micera said.
“The idea would be that it could deliver two or more sensations. You could have a pinch and receive information from three fingers, or feel movement in the hand and wrist,” Dr Micera said.
“We have refined the interface [connecting the hand to the patient], so we hope to see much more detailed movement and control of the hand,” he told the meeting.
The plan is for the patient to wear the bionic hand for a month to see how he adapts to the artificial limb. If all goes well, a full working model will be ready for testing within two years, Dr Micera said.
One of the unresolved issues is whether patients will be able to tolerate having such a limb attached to them all the time, or whether they would need to remove it periodically to give them a rest.
Another problem is how to conceal the wiring under the patient’s skin to make them less obtrusive. The electrodes of the prototype hand to be fitted later this year will be inserted through the skin rather than underneath it but there are plans under development to place the wiring subcutaneously, Dr Micera said.
Duke University researchers have effectively given laboratory rats a “sixth sense” using an implant in their brains.
An experimental device allowed the rats to “touch” infrared light – which is normally invisible to them.
The team at Duke University fitted the rats with an infrared detector wired up to microscopic electrodes that were implanted in the part of their brains that processes tactile information.
The results of the study were published in Nature Communications journal.
The researchers say that, in theory at least, a human with a damaged visual cortex might be able to regain sight through a device implanted in another part of the brain.
Lead author Miguel Nicolelis said this was the first time a brain-machine interface has augmented a sense in adult animals.
The experiment also shows that a new sensory input can be interpreted by a region of the brain that normally does something else (without having to “hijack” the function of that brain region).
“We could create devices sensitive to any physical energy,” said Prof Nicolelis, from the Duke University Medical Center in Durham, North Carolina.
“It could be magnetic fields, radio waves, or ultrasound. We chose infrared initially because it didn’t interfere with our electrophysiological recordings.”
His colleague Eric Thomson commented: “The philosophy of the field of brain-machine interfaces has until now been to attempt to restore a motor function lost to lesion or damage of the central nervous system.
“This is the first paper in which a neuroprosthetic device was used to augment function – literally enabling a normal animal to acquire a sixth sense.”
In their experiments, the researchers used a test chamber with three light sources that could be switched on randomly.
They taught the rats to choose the active light source by poking their noses into a port to receive a sip of water as a reward. They then implanted the microelectrodes, each about a tenth the diameter of a human hair, into the animals’ brains. These electrodes were attached to the infrared detectors.
The scientists then returned the animals to the test chamber. At first, the rats scratched at their faces, indicating that they were interpreting the lights as touch. But after a month the animals learned to associate the signal in their brains with the infrared source.
They began to search actively for the signal, eventually achieving perfect scores in tracking and identifying the correct location of the invisible light source.
One key finding was that enlisting the touch cortex to detect infrared light did not reduce its ability to process touch signals.
In a proposal almost as fanciful as the fictional 20,000 Leagues Under the Sea by Jules Verne, the Defense Advanced Research Projects Agency kicked off a research project last Friday to develop sensor systems that could be placed miles below the surface of the ocean and activated when needed by a remote command.
DARPA said it wants to develop a system that can store unmanned sensors such as waterborne or airborne cameras, decoys, network nodes, beacons and jammers, in watertight capsules that can withstand pressure at depths up to six kilometers (3.7 miles) and then be launched to the surface “after years of dormancy.”
Nearly half of the world’s oceans have depths deeper than 4 kilometers (2.5 miles), DARPA said, “which provides a “vast area for concealment of storage” and this concealment “also provides opportunity to surprise maritime targets from below, while its vastness provides opportunity to simultaneously operate across great distance,” DARPA said.
The agency said it envisions the subsystems of its Upward Falling Payloads projects will consist of a sensor payload, a “riser” providing pressure tolerant encapsulation of the payload and a communication system triggering launch of the payload stored on a container with an inner, 4-7/8 inch diameter and a length of 36 inches.
In the first stage of the three-phase project expected to cost no more than $1.75 million, DARPA wants researchers to concentrate on a communications system that avoids “false triggers” of the deep-sea systems and can operate at long distances from the submerged sensors. Proposals for this phase also should detail the design of a capsule and riser system that will work after sitting for years on the seabed, and potential sensor systems for military or humanitarian use.
The second phase of the project calls for the communication system to “wake up” the system on the seabed and launch it, with tests planned the Western Pacific in 2015 and 2016,though tests also could be conducted in the Atlantic or offshore from Hawaii, DARPA said.
In the third phase, planned for 2017, DARPA plans tests of a completely integrated and distributed Upward Falling Payloads system at full depth in the Western Pacific.
Proposals are due March 12 and DARPA expects to make an award in June.
A Norwegian company is breaking with convention and switching to an alternative energy it hopes will be safer, cleaner and more efficient. But this isn’t about ditching fossil fuels, but rather about making the switch from uranium to thorium. Oslo based Thor Energy is pairing up with the Norwegian government and US-based (but Japanese/Toshiba owned) Westinghouse to begin a four year test that they hope will dispel doubts and make thorium the rule rather than the exception. The thorium will run at a government reactor in Halden.
Thorium was discovered in 1828 by the Swedish chemist Jons Jakob Berzelius who named it after the Norse god of thunder, Thor. Found in trace amounts in rocks and soil, thorium is actually about three times more abundant than uranium.
The attractiveness of thorium has led others in the past to build their own thorium reactors. A reactor operated in Germany between 1983 and 1989, and three operated in the US between the late sixties and early eighties. These plants were abandoned, some think, because the plutonium produced at uranium reactors was deemed indispensable to many in a Cold War world.
Thorium is ‘fertile,’ unlike ‘fissile’ uranium, which means it can’t be used as is but must first be converted to uranium-233. A good deal of research has been conducted to determine if fuel production, processing and waste management for thorium is safe and cost effective. For decades many have argued that thorium is superior to the uranium in nearly all of the world’s nuclear reactors, providing 14 percent of the world’s electricity. Proponents argue that thorium reacts more efficiently than uranium does, that the waste thorium produces is shorter lived than waste from uranium, and that, because of its much higher melting point, is meltdown proof. An added plus is the fact that thorium reactors do not produce plutonium and thus reduce the risk of nuclear weapons proliferation.
Some experts maintain that the benefits of thorium would be maximized in molten salt reactors or pebble bed reactors. The reactor at Halden is not ideal for thorium as it is a ‘heavy water’ reactor, built for running uranium. But it is also a reactor that has already received regulatory approval. Many thorium supporters argue that, rather than wait for ideal molten salt or pebble bed reactors tests should be performed in approved reactors so that their benefits can be more quickly demonstrated to the world.
But is thorium really cheaper, cleaner and more efficient than uranium? And if so, do the added benefits really warrant the cost and effort to make the switch? Data is still pretty scarce, but at least one report is urging us to not believe the hype.
Through their National Nuclear Laboratory the UK’s Department of Energy & Climate Change released a report in September that stated: “thorium has theoretical advantages regarding sustainability, reducing radiotoxicity and reducing proliferation risk. While there is some justification for these benefits, they are often overstated.” The report goes on to acknowledge that worldwide interest in thorium is likely to remain high and they recommend that the UK maintain a “low level” of research and development into thorium fuel.
The place where thorium is proven either way could be China. The country is serious about weaning itself off of fossil fuels and making nuclear power their primary energy source. Fourteen nuclear power reactors are in operation in China today, another 25 under construction, and there are plans to build more. And in 2011 they announced plans to build a thorium, molten salt reactor. So whether it be Norway, the UK, China, or some other forward-thinking countries, we’ll soon find out if thorium reactors are better than uranium ones, at which point more countries may want to join the thorium chain reaction.
The PAL-V ONE, which looks like a cross between a three-wheeler and a helicopter, uses a rear-mounted propeller to take off and a free-spinning rotor on top for lift. Made by PAL-V in the Netherlands, it needs about 200 meters to take off and costs nearly $300,000.
It's Interesting 