For nearly 100 years, scientists thought they understood everything there was to know about how metals bend.
They were wrong.
Materials science and engineering researchers at the University of Wisconsin–Madison have demonstrated that the rules of metal-bending aren’t so hard and fast after all. They described their findings Aug. 9 in the journal Nature Communications.
Their surprising discovery not only upends previous notions about how metals deform, but could help guide the creation of stronger, more durable materials.
“This creates new opportunities for materials design,” says Izabela Szlufarska, a professor of materials science and engineering at UW–Madison. “It adds another parameter we can control to enable strength and ductility.”
Ductility is the ability of a metal to bend. Most approaches to increase a metal’s strength do so at the expense of flexibility — and as metals become more resistant to bending, they’re more likely to crack under pressure.
Transparent electrodes are a critical component of solar cells and electronic displays. To collect electricity in a solar cell or inject electricity for a display, you need a conductive contact, like a metal, but you also need to be able to let light in (for solar cells) or out (for displays).
Metal is opaque, so the current techniques use metal oxides, most often indium tin oxide — a near-critical rare earth metal — as the conductive contact. Because supplies of this rare earth metal are limited, Lawrence Livermore National Laboratory (LLNL) researchers have turned to ordered metal nanowire meshes that provide high transmissivity (due to the small diameters of the nanowires), high electrical connectivity (due to the many contact points in the mesh) and use more common elements. The research appears in the journal Soft Matter.
The nanowire arrays also have applications for optical metamaterials — composite materials usually made of metals and dielectrics — that have unique optical properties not found in nature. For example, all naturally occurring materials have a positive index of refraction. But metamaterials can be designed to have a negative index of refraction, which means that light passing through this material would go in the opposite direction from what one would normally see, and can create structures like cloaking devices and perfect lenses.
A thin film that reflects light in intriguing ways could be used to make road signs that shine brightly and change color at night, according to a study that will be published on Aug. 9 in Science Advances.
The technology could help call attention to important traffic information when it’s dark, with potential benefits for both drivers and pedestrians, researchers say.
The film consists of polymer microspheres laid down on the sticky side of a transparent tape. The material’s physical structure leads to an interesting phenomenon: When white light shines on the film at night, some observers will see a single, stable color reflected back, while others will see changing colors. It all depends on the angle of observation and whether the light source is moving.
The research was led by Limin Wu, Ph.D., at Fudan University in China, whose group developed the material. Experts on optics at the University at Buffalo made significant contributions to the work, providing insight into potential applications for the film, such as employing it in nighttime road signs.
So I'm pretty much top tier terrified because the Amazon Rainforest is on fire. Like, that's seriously bad, isn't it??? How are we supposed to bounce back from this…?
Hey Anon! I’ve gotten a lot of asks about the Amazon forest fire situation so I’m going to address them all here.
The most concerning thing about the Amazon fires isn’t necessarily the fires themselves, but the reason that there are so many this year: This is almost certainly because Brazil’s current president is very anti-environmentalist, which has led to more clearing of the forest (which involves setting fires).
The fires themselves aren’t actually a new threat. People have been practicing slash-and-burn agriculture in the Amazon for a long time. What’s different this year is that there seem to be more fires than usual and they are impacting densely populated locations.
Something that I think is being glossed over by many of the images and headlines being passed around is that it’s very normal for there to be forest fires in and around the Amazon at this time of year.
Brazil’s National Institute for Space Research says that this is a record year for forest fires in Brazil since they started monitoring fires via satellite in 2013.
A manager for Global Forest Watch has said that the fires this year are roughly equivalent to what they saw in 2016 (according to satellite images). Now, 2016 was also a bad year for forest fires, but it goes to show that this level of fire is not unheard of.
So, why are we only hearing about the fires this year if they’ve been this bad before? Probaby because ash clouds darkened the sky over the most populated city in Brazil, which is a big, dramatic, apocalyptic thing that tends to get people’s attention.
Although some meteorologists think the ash over Sao Paulo may have been caused by fires in Paraguay, not even in the Amazon, the air quality in populated areas has been so strongly affected that Amazonas has declared a state of emergency.
To be clear, it is still definitely bad that parts of the Amazon are burning and the fact that the fires are impacting air quality in populated cities poses very real human health risks. We should be speaking out about this, drawing attention to it, and donating to organizations that are working to protect the Amazon. But this is not necessarily an apocalyptic scenario.
And the good news? #PrayforAmazonia went viral on Twitter. Tons and tons of news sources are covering these fires in a way that Amazon forest fires have not been covered in the past. People are talking about Amazon deforestation and its potential impact on climate change.
Do you want to help? Donate! I really cannot stress how much small amounts of money can go a long way in situations like this.
Donate to SOS Amazonia, a Brazilian NGO working to preserve the Amazon (I can’t find any third party information on how reputable this NGO is, but I think this may largely be because of the language barrier-they’ve been operating since the 1980s)
Here’s a few shots from my first few tests. I’ve used a formula/recipe from Clare Davies’ Restology project that she conducted with FabLab, Barcelona. There’s tons that you learn on the job conducting these tests and there can be enormous variables (environment, heat, drying time, texture, flexibility etc) even if you use a similar amount of each material.
Test #1 – For this recipe I used 16g ground charcoal (roughly bashed with a rolling pin), 100ml water, 16g gelatine, 16g of glycerol. After pouring it in to the silicone mould, I left it to dry over the weekend. I came back to a beautiful looking matt texture, that highlighted every detail of the charcoal. It also had a surprising amount of flexibility and is conductive. There’s only one downside to test 1 – it has a slight meaty (porky) smell, even though charcoal it supposed reduce odours. With this in mind, I swapped out the gelatine for agar in subsequent tests.
Test #2 – 25g charcoal (finer grind with a coffee grinder), 100ml of water, 15g Agar. Once again poured this into moulds and left to dry. This version started to split as it dried, and once it was fully dry it crumbled into lots of flakey pieces (see pic 4). Quite clear that without the addition of glycerol it didn’t bind as well.
Test #3 – 25g charcoal, 100ml of water, 10g Agar, 15g Agar. This test took quite some time to dry and appeared to have a more flexibility. Once fully dried it also started to crack. As much as I do not wish to use gelatine to make a more natural product, I feel that I might need to proceed with it as it has proved the most successful binding agent.
At the start of these tests, I used charcoal sticks that could be found at any art shop – but at £5 a pack for minute quantity, I knew I would have to look for a way of procuring bulk amounts to create a large scale piece. I contacted the Coates to see if there was the potential to partner with them and use any waste offcuts from their willow charcoal production, however they produce no waste. So I managed to find bulk bags of activated charcoal that are used as filters in aquatics – which in fact has an even greater conductivity to artists charcoal.
Needle-less electrospinning appeared in the early 1970s, when Simm and coworkers filed a patent on using an annular electrode to electrostatically spin fibers for filtration applications. Next, Lukas et al. investigated the self-organization of charged jets initiated from the open free-liquid surface in the electrospinning process. Lin and colleagues developed a rotating spiral coil spinneret, which had a high fiber production rate with well-controlled fiber morphology. Liu et al. electrospun nanofibers by blowing air into the polymer solution. The bubbles generated assisted in jet initiation. Since 2008, growing research has been devoted to needle-less electrospinning. Research publications have been increasing constantly over the years. Over 100 articles about needle-less electrospinning or free-surface electrospinning have been published since 2007. The publication number between 2014 and 2016 was approximately 10 times more than that of 2007e2013 (Fig. 7.2A). Research is widespread in many countries. China, Australia, and the Czech Republic take about 80% of publications, followed by the United States, Germany, and England (Fig. 7.2B).