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Discovering Oxygen: A Brief History

Because there are three different dead guys who regularly vie for credit for discovering oxygen, we’ve staged a little friendly competition to establish which of these great men deserves the title of the O-master. In evaluating the contenders, we’ll look at when they isolated oxygen and how their experiments furthered our understanding of the element. In addition to bragging rights, the winner takes home one zillion liters of oxygen.

Contender 1: Carl Wilhelm Scheele

Nationality: Swedish
Occupation: Apothecary

Biggest Accomplishment: In 1772, he was the first person to figure out a way – actually a couple of ways - to isolate oxygen. He discovered that mercuric oxide, silver carbonate, magnesium nitrate, and potassium nitrate all gave off the same gas when heated. Scheele dubbed the mystery element “fire air” because he noticed that it produced sparks when it came into contact with charcoal dust.

Other Biggest Accomplishment: Discovered chlorine

Biggest Shortcoming:

Bad timing. Scheele didn’t publish his discovery until 1777, in a treatise called Chemical Observations and Experiments on Air and Fire. By that time, Joseph Priestley had already written a paper describing his findings and published the comprehensive Experiments and Observations on Air. Lavoisier had also successfully isolated the gas. Because Scheele waited so long to get the word out, his groundbreaking experiment was often overlooked by other scientists, earning him the nickname “Hard Luck Scheele.”

Contender 2: Joseph Priestley

Nationality: British

Occupation: Radical Unitarian Minister

Biggest accomplishment: In 1771, Priestley noticed that a mouse in a sealed jar would eventually collapse. He then tried slipping a sprig of mint inside and realized the plant magically revived his subject. Realizing that plants did something to freshen up the air, he wrote to his friend Benjamin Franklin, saying he hoped his discovery would stop people from cutting down so many trees.

Priestley didn’t actually isolate this mystery gas until August 1, 1774, when he heated some mercuric oxide powder and discovered that it gave off a gas that could reignite a glowing ember. He collected large amounts of the gas and tried breathing it himself. After a few puffs, Priestley was hooked. He declared, “My breast felt peculiarly light and easy for some time afterward.”

Other Biggest Accomplishment: Invented seltzer water

Biggest Shortcoming: Priestley just wouldn’t let go of phlogiston theory – a crackpot hypothesis that argued combustion was fueled by an invisible substance called phlogiston. Priestley believed that his mystery gas supported combustion because it was pure and could absorb phlogiston released by burning substances. That’s why he was pushing to name oxygen “dephlogisticated air.”

Contender 3: Antoine Laurent Lavoisier

Nationality: French

Occupation: Tax farmer/Commissioner of the Royal Gunpowder and Saltpeter Administration

Biggest Accomplishment: Lavoisier debunked phlogiston theory. Up until then, scientists couldn’t explain why tin gained weight when it was burned; if it was releasing phlogiston, it should lose weight. Lavoisier realized that there was no way phlogiston could have a negative mass and set out to prove that combustion was caused by something else. He heated Mercury until calx formed, then he heated the calx until it gave off a clear gas. Lavoisier realized combustion resulted from a chemical reaction with this gas – not some flammable mystery element called phlogiston. He dubbed the gas “oxygen” – a name that referred to its ability to create acids.

Other Biggest Accomplishment: Helped establish this thing called the metric system, which some people supposedly use.

Biggest Shortcoming: Lavoisier might have been the one to name oxygen, and for that, we’re grateful (nobody would be caught dead in a dephlogisticated air bar). However, he was not the first to isolate the gas or recognize its unique properties. His methods weren’t even original. In fact, Lavoisier had been in contact with both Priestley and Scheele and borrowed from their experiments.

And the O-Master Is...

We’re giving this one to Joseph Priestley. Although he gets points for publishing first, his real breakthrough was his realization that plants gave off oxygen. This discovery enabled future scientists to understand cellular respiration and photosynthesis – both of which are absolutely essential to life on Earth. We’re also giving Priestley points for recognizing the commercial potential of oxygen when he anticipated that the pure air could be a hit at parties. Sure enough, over 200 years later, oxygen bars have become a thing!

So next time you take a breath (hopefully soon), think of Joseph Priestley and his iconic experiment, which took place exactly 238 years ago today.

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Penn Vet Working Dog Center
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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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Medicine
New Cancer-Fighting Nanobots Can Track Down Tumors and Cut Off Their Blood Supply
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iStock

Scientists have developed a new way to cut off the blood flow to cancerous tumors, causing them to eventually shrivel up and die. As Business Insider reports, the new treatment uses a design inspired by origami to infiltrate crucial blood vessels while leaving the rest of the body unharmed.

A team of molecular chemists from Arizona State University and the Chinese Academy of Sciences describe their method in the journal Nature Biotechnology. First, they constructed robots that are 1000 times smaller than a human hair from strands of DNA. These tiny devices contain enzymes called thrombin that encourage blood clotting, and they're rolled up tightly enough to keep the substance contained.

Next, researchers injected the robots into the bloodstreams of mice and small pigs sick with different types of cancer. The DNA sought the tumor in the body while leaving healthy cells alone. The robot knew when it reached the tumor and responded by unfurling and releasing the thrombin into the blood vessel that fed it. A clot started to form, eventually blocking off the tumor's blood supply and causing the cancerous tissues to die.

The treatment has been tested on dozen of animals with breast, lung, skin, and ovarian cancers. In mice, the average life expectancy doubled, and in three of the skin cancer cases tumors regressed completely.

Researchers are optimistic about the therapy's effectiveness on cancers throughout the body. There's not much variation between the blood vessels that supply tumors, whether they're in an ovary in or a prostate. So if triggering a blood clot causes one type of tumor to waste away, the same method holds promise for other cancers.

But before the scientists think too far ahead, they'll need to test the treatments on human patients. Nanobots have been an appealing cancer-fighting option to researchers for years. If effective, the machines can target cancer at the microscopic level without causing harm to healthy cells. But if something goes wrong, the bots could end up attacking the wrong tissue and leave the patient worse off. Study co-author Hao Yan believes this latest method may be the one that gets it right. He said in a statement, "I think we are much closer to real, practical medical applications of the technology."

[h/t Business Insider]

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