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The Origins of the Periodic Table

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It's Elemental

Contrary to schoolyard rumors, no one created the periodic table just to torture you—it all started with the elements. As early as 330 BCE, Aristotle created a four-element table: earth, air, fire, and water. (We'd sign up for a test on that periodic table, no problem.) But it wasn't until the late 1700s that Antoine Lavoisier wrote the first list of 33 elements. He classified them as metals and nonmetals, though we now know that some were compounds or mixtures. Other chemists found 63 elements through the mid-1800s, including their properties and compounds, and during that time, scientists also started noticing unexpected patterns in the properties.

For example, Johann Dobereiner discovered that the atomic weight of strontium fell exactly between the weights of calcium and barium, and all three had similar properties. From this, he created the Law of Triads, which said that in triads of elements, the properties of the middle element would be the average of the other two, if you ordered the elements by atomic weight.

When other scientists tested the theory, they basically found that the triads weren't really triads but parts of larger groups. (For instance, fluorine was added to the halogen "triad.") The main drag on their research was inaccurate measuring tools—if you're trying to order the elements by weight to figure out their relationships, it would have helped to know the correct values.

Shoddy measuring tools didn't stop progress, though. Enter French geologist A.E. Beguyer de Chancourtois, who lined up the elements on a cylinder in order of increasing atomic weight. By stacking the closely related elements, he noticed that their properties repeated every seven elements. The chart had one major flaw: it included ions and compounds as well as elements. A year later (in 1864), John Newlands created the Law of Octaves. Newlands noticed the same pattern that de Chancourtois did—repetition within columns. He also arranged the elements in order of atomic weight and observed similarities between the first and ninth elements, third and eleventh, etc. Much like de Chancourtois, Newlands had one major oversight in his table: he didn't leave any spaces for elements that hadn't been discovered yet.

Symbol Minded

Five years later, we got not one, but the first two, full-fledged periodic tables. Working independently, Lothar Meyer and Dmitri Mendeleev both developed periodic tables. Meyer had published a textbook in 1864 that included an abbreviated version of a periodic table, demonstrating periodic changes in relation to atomic weight. He completed an extended table in 1868 and gave it to a colleague—who obviously took a bit too long to review it. During the review time, Mendeleev's table was published (1869), and Meyer's didn't appear until the next year.

To be fair, Mendeleev's thought process also appears to have been a little bit different than Meyer's. After noticing several patterns, he decided to create a card for each of the 63 known elements that would include the symbol, atomic weight, and chemical and physical properties. He arranged the cards on a table in order of atomic weight and grouped elements with similar properties. The table ended up showing not only group relationships, but vertical, horizontal, and diagonal relationships as well. (Alas, poor Mendeleev came only one vote away from being awarded the 1906 Nobel Prize for his work.) Unlike Meyers, Mendeleev was able to use the gaps in his table to make predictions about yet-to-be-discovered elements, and remarkably, many turned out to be true.

[See Also: Name the Noble Gases in 1 Minute]

This article was written by Liz Hunt and excerpted from the mental_floss book In the Beginning: The Origins of Everything. You can pick up a copy in our store. Also available in our store is the Periodic Table shower curtain.

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technology
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Health
One Bite From This Tick Can Make You Allergic to Meat
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iStock

We like to believe that there’s no such thing as a bad organism, that every creature must have its place in the world. But ticks are really making that difficult. As if Lyme disease wasn't bad enough, scientists say some ticks carry a pathogen that causes a sudden and dangerous allergy to meat. Yes, meat.

The Lone Star tick (Amblyomma americanum) mostly looks like your average tick, with a tiny head and a big fat behind, except the adult female has a Texas-shaped spot on its back—thus the name.

Unlike other American ticks, the Lone Star feeds on humans at every stage of its life cycle. Even the larvae want our blood. You can’t get Lyme disease from the Lone Star tick, but you can get something even more mysterious: the inability to safely consume a bacon cheeseburger.

"The weird thing about [this reaction] is it can occur within three to 10 or 12 hours, so patients have no idea what prompted their allergic reactions," allergist Ronald Saff, of the Florida State University College of Medicine, told Business Insider.

What prompted them was STARI, or southern tick-associated rash illness. People with STARI may develop a circular rash like the one commonly seen in Lyme disease. They may feel achy, fatigued, and fevered. And their next meal could make them very, very sick.

Saff now sees at least one patient per week with STARI and a sensitivity to galactose-alpha-1, 3-galactose—more commonly known as alpha-gal—a sugar molecule found in mammal tissue like pork, beef, and lamb. Several hours after eating, patients’ immune systems overreact to alpha-gal, with symptoms ranging from an itchy rash to throat swelling.

Even worse, the more times a person is bitten, the more likely it becomes that they will develop this dangerous allergy.

The tick’s range currently covers the southern, eastern, and south-central U.S., but even that is changing. "We expect with warming temperatures, the tick is going to slowly make its way northward and westward and cause more problems than they're already causing," Saff said. We've already seen that occur with the deer ticks that cause Lyme disease, and 2017 is projected to be an especially bad year.

There’s so much we don’t understand about alpha-gal sensitivity. Scientists don’t know why it happens, how to treat it, or if it's permanent. All they can do is advise us to be vigilant and follow basic tick-avoidance practices.

[h/t Business Insider]

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