Opinions vary on what caused the Hindenburg to explode so suddenly.

On May 6, 1937—75 years ago this week—the Hindenburg airship was about the complete its 35th trip across the Atlantic, having departed from Frankfurt, Germany and nearly arrived at Lakehurst, New Jersey. Then, suddenly, after thousands of miles of uneventful travel, the great zeppelin caught fire while less than 300 feet from the ground. Within a minute of the first signs of trouble, the entire ship was incinerated, and the burning wreckage crashed to the ground. Thirty-five of the 97 people on board perished in the disaster.

Then the finger-pointing began. From the very start, observers disagreed about what exactly sparked the explosion and what caused it to burn so quickly. In the years since, scientists, engineers and others have used science to weigh in on the debate and attempt to solve the mystery of the Hindenburg.

During an era of tension between the United States and Germany’s new Nazi government, suspicious minds quickly alighted on the idea that a crew member or passenger had sabotaged the airship, intentionally starting a fire. However, nothing more than circumstantial evidence was ever put forth to support the idea. Realistic alternatives for the cause of the explosion include a buildup of static electricity, a bolt of lightning or a backfiring engine, but at this point it’s impossible to determine what exactly caused the spark.

A different question is what provided the fuel for the explosion—and this is where the science really gets interesting. Initially, observers assumed that some of the lighter-than-air hydrogen that kept the ship aloft somehow leaked from its enclosed cells, mixing with the oxygen in the air to create an incredibly flammable substance. Photographs taken right after the initial explosion show lines of fire along boundaries between the fuel cells, and crew members stationed in the stern reported seeing the actual cells burn, supporting the idea that leaking hydrogen caused the craft to explode so violently. Many have theorized that, during one of the sharp turns the ship took just before exploding, one of the bracing wires inside snapped, puncturing one of the cells.

Then, in 1996, retired NASA scientist Addison Bain, who had years of experience working with hydrogen, presented a new idea: the incendiary paint hypothesis. As part of his argument that hydrogen can be safely used for transportation and other purposes, Bain claimed that the fire was initially fueled by a special paint used on the zeppelin’s skin. The varnish compound included chemicals such iron oxide, which can be used as rocket fuel.

Bain also pointed out that the hydrogen inside the cells had been given a garlic scent, to help crew members detect a leak, but no one reported smelling garlic at the time of the explosion. He also said that a fire fueled by hydrogen would produce a blue flame, but the fire was a bright red. In his scenario, the mystery spark would have ignited the varnish rather than leaking hydrogen—meaning that a design flaw, rather than the inherent risks of hydrogen, had caused the disaster.

In 2005, a team of researchers led by A.J. Dessler, a physicist at Texas A&M, published a detailed study in which they attempted to determine whether the chemicals in the varnish could possibly account for the fire. Their answer: no way. Their calculations indicate that, if fueled by the paint alone, the airship would have taken roughly 40 hours to burn completely, rather than the 34 seconds it took for it to be consumed. In the lab, they burned replica pieces of the Hindenburg‘s outer covering, which confirmed their theoretical calculations—and indicated that the paint alone could not have fueled the fire.

So, more than 75 years later, we’re still not quite sure what to believe about the Hindenburg disaster. Can the use of hydrogen gas in transportation be safe? Or is a vehicle filled with flammable gas simply an accident waiting to happen? However it was caused, the terrible explosion had one long-lasting effect: It permanently put airship travel on the back burner.

Read about a new exhibit at the Smithsonian’s National Postal Museum about the Hindenburg and read an eyewitness account of the disaster from a grounds crew member.

Grapefruit and grapefruit juice can adversely interact with certain medications. Image courtesy of the FDA

Last month, the FDA issued an unusual warning. It wasn’t about counterfeit prescription drugs, an unsafe medicine, or a recalled product. Rather, the warning was for something that grows naturally in the groves of Florida: the sour, juicy grapefruit.

The FDA consumer update confirmed what users of drugs like statins have known for a long time—you shouldn’t eat grapefruit or drink grapefruit juice if you’re taking any of a number of medications. In the report, Shiew Mei Huang, the acting director of the FDA’s Office of Clinical Pharmacology, noted that for many drugs, “the juice increases the absorption of the drug into the bloodstream. When there is a higher concentration of a drug, you tend to have more adverse events.”

The strange “grapefruit effect” was first discovered entirely by accident. As part of a 1989 study, scientists at London’s Victoria Hospital were attempting to discover whether ethanol—the molecule responsible for the intoxicating effects of alcoholic drinks—could negatively interact with a drug called felodipine, developed to treat high blood pressure. They happened to use grapefruit juice to mask the taste of the alcohol, and discovered unexpectedly high levels of the drug in the blood. After further investigation, they realized it wasn’t the alcohol causing the surge—it was grapefruit.

The danger of mixing grapefruit and medication is most widely known for cholesterol-lowering statin drugs like Zocor and Lipitor, but recent studies have indicated grapefruit can interact with a longer list of medicines, including those prescribed to treat high blood pressure (like Nifediac and Afeditab), depression or anxiey (Zoloft and BuSpar) and erectile dysfunction (Viagara and Cialis). Even some over-the-counter antihistamines, like Allegra, may be affected. The negative interactions are greatest if the grapefruit is consumed less than four hours before the drugs are ingested, the FDA says.

What are the adverse effects? Increased concentration of the medications force the liver to work harder, increasing the risk of liver damage, potentially leading to muscle breakdown and kidney failure. But surprisingly, for a few drugs, including Allegra, grapefruit actually lowers the concentration of the medicine in the blood, reducing its effectiveness.

These opposite effects of grapefruit work via entirely different biological mechanisms. In the first case—when drug concentrations are dangerously increased—certain compounds in the fruit known as furanocoumarins inhibit the action of an enzyme, called CYP3A4, which occurs in the small intestine. Normally, CYP3A4 starts to break down the drugs, so they are somewhat metabolized by the time they hit the bloodstream. But with CYP3A4 inhibited, larger amounts pass into the blood.

The consequences of this can vary widely among individuals, who naturally start out with different levels of the enzyme. The particular drug’s potential for toxic effects also plays a role. For some drugs, habitually taking them with grapefruit can lead to liver and kidney damage over the long term. For others, a single episode may lead to toxic levels of the medication in the blood.

The mechanism by which grapefruit reduces the effectiveness of other drugs—antihistamines, such as Benadryl and Allegra, in particular—is less well understood. In this case, substances in the fruit interfere with transporter proteins on the surfaces of cells. Because of this interference, the medication does not enter cells as efficiently and is less effective.

The FDA notes that it has begun requiring certain medications to be labeled if they are not to be taken with grapefruit, and advises consumers to ask their doctor or pharmacist if they are unsure.

Still, grapefruit lovers can take heart: A team of citrus breeders at the University of Florida is at work developing grapefruit-pummelo hybrids that contain little or no furanocourmarins, which should be able to be eaten safely with any medication. The researchers predict they will be able to release commercial varieties of the new fruit within a few years.

A sample of highly enriched uranium (via wikimedia commons)

Enriched uranium is back in the news with a report that Iran has begun creating the stuff at a heavily fortified site in the north of that country. But what is enriched uranium?

Uranium is element 92 on the periodic table–every molecule has 92 protons in its nucleus. The number of neutrons can vary, and that’s the difference between the three isotopes of uranium that we find here on Earth. Uranium-238 (92 protons plus 146 neutrons) is the most abundant form, and about 99.3 percent of all uranium is U-238. The rest is U-235 (0.7 percent), with a trace amount of U-234.

Uranium has a bad reputation (it is radioactive, after all), but U-238 has a very long half-life, meaning that it can be handled fairly safely as long as precautions are taken (as seen in the video below). More importantly here, though, U-238 isn’t fissile–it can’t start a nuclear reaction and sustain it.

U-235, however, is fissile; it can start a nuclear reaction and sustain it. But that 0.7 percent in naturally occurring uranium isn’t enough to make a bomb or even a nuclear reactor for a power plant. A power plant requires uranium with three to four percent U-235 (this is known as low-enriched or reactor-grade uranium), and a bomb needs uranium with a whopping 90 percent U-235 (highly enriched uranium).

Uranium enrichment, then, is the process by which a sample of uranium has its proportion of U-235 increased.

The first people to figure out how to do this were the scientists of the Manhattan Project during World War II. They came up with four methods to separate the U-235 from uranium ore: gaseous diffusion, electromagnetic separation, liquid thermal diffusion and centrifugation, though at the time they deemed centrifugation not practical for large-scale enrichment.

The most common methods for enriching uranium today are centrifugation (decades of development have made this method more efficient than it was during WWII) and gaseous diffusion. And other methods are being developed, including several based on laser techniques.

Highly enriched uranium, the type used in bombs, is expensive and difficult to create, which is why it remains a barrier, though not an insurmountable one, for countries wishing to develop nuclear weapons. And once a nation develops the capability for enriching uranium beyond reactor grade (Iran has reportedly begun to produce uranium enriched up to 20 percent), the path to weapons-grade uranium is significantly sped up.

Find out more about nuclear concerns in Iran from Arms Control Wonk, the Carnegie Endowment for International Peace and ISIS NuclearIran, from the Institute for Science and International Security.

And learn more about the element uranium, including depleted uranium, in this selection from the Periodic Table of Videos:

In this image from Science on Ice, graduate student Maria Tausendfreund collects a water sample from an Arctic melt pond during a brief period of 'ice liberty.' (photo by Chris Linder)

Find the perfect holiday gift for each person on your list can be difficult, especially if you don’t share the same interests or hobbies. What can you buy for someone who loves science? Here are some ideas from the Smithsonian staff; add your own in the comments below.

For the photography lover
Science on Ice: Four Polar Expeditions: Photojournalist Chris Linder has been documenting polar science expeditions for the past several years, and he’s collected his best photos in this new book. The beautiful photography is accented by essays from the science writers, including Smithsonian freelancers Helen Fields and Hugh Powell, who accompanied Linder on the trips (Helen’s trip may seem familiar to blog readers; she wrote to us from the ship Healy in the Bering Sea). What makes this book truly special is that Linder’s photos include not just adorable wildlife and stunning Arctic landscapes but also fascinating images of scientists at work and at play. “The scientists I know are as tough as they ships they sail on,” Linder writes in the book. “By photographing scientists working in the field, I hope to create a new stereotype…[and] by extension, I hope that readers, particularly students, will develop a stronger interest in science as a career.”

For the book lover who doesn’t need another book
The Origin of Species on a T-shirt: Out of Print Clothing sells t-shirts, tote bags, stationary and other items emblazoned with iconic book covers, such as Charles Darwin’s classic work. And for every item sold, the company donates one book through Books for Africa, so your holiday giving goes just a bit further.

For the animal lover
An “Ape-stract” Painting: Chimpanzees, Cheeta and his grandson Jeeter, use a paintbrush dipped in bright colors to create their abstract creations, which are available with a donation to the C.H.E.E.T.A. Primate Sanctuary in California.

For the stuffed animal lover
Biochemies DNA Molecule Plush Dolls: Chemical biology graduate student Jun Axup started making these cute little toys a couple years ago to promote science education. The cute little molecules, with smiley faces, come in a set of four: A, G, C and T.

For the neuroscientist or brain surgeon
Brain Freeze Ice Cube Tray: This silicone tray makes four brain-shaped ice cubes (or jello molds) at a time. Perfect for when you need a cooler head.

For the mathematician
I Heart Math T-shirt: Express your love of mathematics in a way only people who remember what imaginary numbers are will understand.

For the budding inventor
Reinventing Edison Build Your Own Lightbulb Kit: If someone wants to build a better lightbulb, she can start by learning how to build the kind Edison invented. Perhaps tinkering with the original model will lead to insights about where to go next on the inventing path.

For the budding biologist
Bacterial Growth Science Kit: This kit contains enough petri dishes, agar, pipettes and test tubes to run your own mini science lab. What kind of bacteria could you grow? It’s all around you, from your skin to your computer to your kitchen sink. Just be prepared to be grossed out when you discover just how many microorganisms are there to be found.

For the budding chemist/environmental scientist
Environmental Student Lab Test Kit: With this kit, your little scientist can perform five different tests on water and four on air, examining things like dissolved oxygen levels in the creek down the street or particulate levels outside your home. And unlike a standard chemistry set–always a fun buy for a little chemist–you may get some useful information from this gift.

And for yourself, to wear around your anti-evolution relatives
“My ancestors spent 3.8 billion years evolving out of the primordial ooze and all I got was this lousy t-shirt” T-Shirt: This tee, from the National Center for Science Education (it’s the last item on the store page), will let you promote the teaching of evolution while heeding your mother’s advice to keep your mouth shut on the topic during that holiday visit to Uncle Fred’s house. (And if you want to be sneaky with the gift giving on that trip, you could get your niece or nephew an Evolvem stuffed animal, which evolves from one creature to the next.)

Water crystallizes into ice at 32 degrees F, but not always (courtesy of flickr user s.alt)

The title of this post would seem an appropriate question for an elementary-school science exam, but the answer is far more complicated than it first appears. We’ve all been taught that water freezes at 32 degrees Fahrenheit, 0 degrees Celsius, 273.15 Kelvin. That’s not always the case, though. Scientists have found liquid water as cold as -40 degrees F in clouds and even cooled water down to -42 degrees F in the lab. How low could they go?

That turns out to be a tricky problem to answer. When liquid water is cooled below -42 degrees F, it crystallizes into ice too quickly for scientists to measure the temperature of the liquid. So Emily Moore and Valeria Molinero of the University of Utah developed a sophisticated computer simulation of 32,768 water molecules (fewer molecules than can be found in a raindrop) that let them see what happened to the water’s heat capacity, density and compressibility as it supercooled and determine what happened as 4,000 of those molecules froze. Their results appear in the journal Nature.

As the temperature of the water approaches -55 degrees F, the water molecules form tetrahedrons, with each molecule loosely bonding to four other molecules. The density of the water decreases, its heat capacity increases and its compressibility increases. “The change in structure of water controls the rate at which ice forms,” Molinero says. “We show both the thermodynamics of water and the crystallization rate are controlled by the change in structure of liquid water that approaches the structure of ice.” Below -55 degrees F, tiny bits of liquid water may still exist, but it would do so only for an incredibly short time, Molinero says.

This supercooling of water is possible because water needs a small nucleus or seed of ice for the molecules to form crystals and in very pure water “the only way you can form a nucleus is by spontaneously changing the structure of the liquid,” Molinero says. Those nuclei won’t form or grow large enough until the structure of the liquid water molecules approaches that of solid ice, which doesn’t happen until the water gets so incredibly cold.

(HT: io9)

One hundred years ago, Marie Curie won her second Nobel Prize, in chemistry, for her 1898 discovery of the elements polonium and radium, which she had painstakingly isolated from a radioactive uranium ore called pitchblende. She named polonium in honor of her homeland Poland (which officially did not exist at the time, as it had been occupied by neighboring countries). Polonium occurs in very low concentrations on the Earth’s surface. It is highly unstable, and all isotopes are radioactive. Here are some of the more interesting things we know about the element.

1. In 2006, Russian ex-KGB agent Alexander Litvinenko, who was living in the United Kingdom after claiming political asylum, died after being poisoned with polonium-210. A British investigation identified Andrei Lugovoy, a former officer in the Russian Federal Protective Service, as the main suspect in the case, but Russia refused to extradite him. Lugovoy is now a member of the Russian lower house of parliament, the Duma.

2. Before 1944, very little polonium had been isolated. The Manhattan Project, however, changed that. Polonium, an emitter of alpha particles, and beryllium, which absorbs alpha particles and emits neutrons, were used in the trigger of the first atomic bombs. The two elements were kept apart until the very last moment; once mixed, they set off the explosion.

3. Polonium-210 can be found in the air. It is created during the decay of radon-222 gas and during the production of phosphorus from phosphate rock. Plants can take up polonium through their roots, or it can be deposited directly on broad-leafed plants. Lichens also absorb polonium directly from the atmosphere. In northern regions, humans can have higher concentrations of polonium because they eat reindeer, which eat lichens.

4. Cigarettes and other tobacco-containing products also have low levels of radioactive polonium. Researchers from the University of California at Los Angeles recently found that tobacco companies knew about the radioactivity as early as 1959. The scientists calculated that this radioactivity, which can cause cancer, is responsible for up to 138 deaths for every 1,000 smokers over a period of 25 years.

5. Because the alpha particles from polonium don’t pass through the epidermis, the substance is not harmful outside the body. If polonium is ingested, 50 percent to 90 percent of the element leaves the body through feces. The rest is deposited mostly in the kidneys, liver and spleen; because it is radioactive, the amount of the element decreases by half every 50 days. The effects of inhaled polonium are localized in the lungs. Smokers have about twice as much polonium in their ribs as non-smokers.

6. The first person to die of polonium poisoning may have been Marie Curie’s daughter Irène Joliot-Curie. In 1946, a capsule of polonium exploded on Joliot-Curie’s lab bench. It is thought that this incident may have been responsible for her death, 10 years later, of leukemia.

Gold bullion from the National Bank of Poland (courtesy of flickr user covilha)

People are buying up gold faster than milk, bread and toilet paper before a Washington blizzard. The New York Times is even holding a debate on whether whole governments should be following the herd. But why gold? Other than the human tendency for imitating magpies (why else would we think the common diamond is so extraordinary?), gold really isn’t all that special. There are far more useful elements out there. And several are even rarer than gold. (I should note that the following list is limited to elements within the Earth’s crust because, let’s face it, no one is going to search any deeper than that, and asteroid mining is out of the question for now.) All of these, like gold, are noble metals, meaning that they are resistant to corrosion.

Gold is rare in the Earth's crust, but several elements are even rarer (credit: USGS)

Platinum (Pt): Most familiar for its use in jewelry, platinum is more often used in the systems that control vehicle emissions in our cars. Other uses include electronics, spark plugs and in drugs to treat cancer.

Palladium (Pd): Palladium is similar to platinum in both appearance and in use; it appears in vehicle emissions equipment and electronics. It’s also a key component in fuel cells.

Ruthenium (Ru): Like platinum and palladium, ruthenium is a silvery metal that does not easily tarnish. It is used as a catalyst and to harden those other similar metals, platinum and palladium.

Rhenium (Re): The last of the naturally occurring elements to be discovered, this silvery metal is used in small amounts with nickel in jet engines. Rhenium isotopes are used to treat liver cancer.

Rhodium (Rh): Some white gold and sterling silver jewelry is plated with rhodium, which improves its appearance. It is also used in aircraft spark plugs, fountain pens and mammography systems.

Osmium (Os): The densest of natural elements—twice as dense as lead—this blue-grey metal finds a home in applications where hardness and durability are essential. Applications include surgical implants, electrical contacts and the tips of fountain pens.

Iridium (Ir): If iridium sounds familiar, that might be because there’s a group of communications satellites named after this element, a hard, brittle and dense metal. Or it could be because the K-T boundary that marks the geologic end of the dinosaurs is laced with iridium; the metal is more common in asteroids and meteorites than in the Earth’s crust. Iridium can also be found in crystals in computer memory devices, deep-water pipes, X-ray telescopes and the equipment that makes rayon fibers.

The space shuttle Atlantis, ready for liftoff. Photo courtesy of NASA

The four astronauts aboard the space shuttle Atlantis will not be alone when they blast into space today (assuming the launch proceeds as scheduled). The last shuttle mission will also carry 30 mice that are part of an experiment to better understand why astronauts lose bone mass when they hang out in low-Earth orbit.

The mouse study is typical of the type of research that seemed to dominate space shuttle science: investigations devoted to figuring out how the human body—and the microbes that parasitize us—cope with space. It’s the kind of work that’s necessary if we want to safely send people on long-term missions to Mars and beyond.

With all of the talk about the end of the space shuttle program, I wondered what other science has happened aboard Atlantis, Challenger, Columbia, Discovery and Endeavour. I found some surprises. Here are my favorite quirky space shuttle science projects:

A rose in space smells as sweet—or sweeter: The fragrance of flowers comes from the plants’ essential oils. Many environmental factors influence the oils that a flower produces—and one of those factors is apparently gravity. In 1998, the perfume manufacturer International Flavors & Fragrances sent a small rose called Overnight Scentsation into space aboard Discovery. Astronauts grew the rose in a special chamber and collected its oils. In the low-gravity conditions of Earth’s orbit, the flower made fewer essential oils, and the oils it did produce smelled different (a “floral rose aroma” instead of “a very green, fresh rosy note”). Back on Earth, the perfume company synthesized the rose’s space oils to create a new fragrance that is now in Shiseido’s perfume called Zen.

The MGM experiment: MGM doesn’t refer to the movie studio or the Las Vegas casino; it stands for “Mechanics of Granular Materials.” With this experiment, researchers in space studied the effects of earthquakes, sort of. On three shuttle missions, the MGM experiment compressed columns of sand to allow researchers to study the sand’s strength and other mechanical properties. Such properties are relevant to many processes on Earth, such as soil liquefaction. Liquefaction is often a problem during earthquakes: the shaking increases the external forces acting on any water in the ground, causing water pressure to go up. The higher water pressure weakens the soil, making it flow like a liquid and causing buildings to sink. Studying sand in space is beneficial because the lower gravity reduces certain stresses that make it difficult to study liquefaction and similar phenomena on Earth. Sadly, the last MGM experiment flew aboard the Columbia mission that broke up during re-entry in 2003.

The Tunguska mystery solved: Technically, this piece of science didn’t occur aboard the space shuttle, but it certainly benefited from the shuttle program. In 1908, an extraterrestrial object hit Russia, flattening almost 3,500 square miles of Siberian forest near the Podkamennaya Tunguska River. Scientists have debated whether an asteroid or comet caused the impact. Space shuttle exhaust points to a comet. Researchers at Cornell University and Clemson University made the connection after noticing the formation of noctilucent (“night shining”) clouds following two shuttle launches. The brilliant clouds likely formed from the hundreds of tons of water vapor emitted from the shuttle’s engine during takeoff. Historical records note that the night sky similarly lit up after the Tunguska event. The researchers say noctilucent clouds were probably the cause of the glow, suggesting that whatever hit Earth must have released a lot of water into the atmosphere. This makes comets the likely culprit because they, unlike asteroids, carry a lot of ice.

These scientific experiments are fun, but do they justify the hefty price tag of the shuttle program? Probably not. Some might say the program’s greatest scientific achievements relate to the satellites that astronauts brought to space or the repairs they made to the Hubble Space Telescope.

I’ll suggest another achievement, one that’s more personal. As someone who grew up during the shuttle’s early days, the program helped steer me down a scientific path. It certainly helped foster my interest in learning about the world around (and above) me.

Before wastewater is treated, scientists can look for traces of illegal drugs. (photo courtesy of flickr user DefMo)

Archaeologists often talk about the importance of trash—you can learn a lot about a culture by looking at what it threw away. Chemists may say the same thing about another kind of waste: sewage. Throughout last year, researchers at the Norwegian Institute for Water Research monitored the illegal drug habits of half a million people in Oslo by chemically sifting through the sewers. The work is an example of the emerging field of “sewage epidemiology.”

The research field has developed over the past decade (Popular Science has a good article on the early days). The idea is that screening for drugs that pass through the body and then get flushed down the toilet may be one of the fastest, most accurate ways to assess a community’s drug use. After all, people can lie in surveys, and segments of the population can be overlooked. It’s harder to manipulate what goes into the sewers (although I can imagine that if sewage epidemiology really takes off, paranoid drug users may look for alternative ways to get rid of their personal waste).

In the Norwegian study, published online in the journal Environmental Science & Technology, Christopher Harman, Malcolm Reid and Kevin Thomas placed chemical samplers in a wastewater treatment plant and, over the course of a year, looked for cocaine, amphetamine, methamphetamine, Ecstasy and the chemicals that these drugs break down into during digestion. They found some interesting results. For example, concentrations of cocaine went up on the weekends, and Ecstasy spiked in the month of May. The researchers note that this peak coincided with “russefeiring,” a two-week celebration for recent high school graduates.

Based on the concentrations of each drug—and knowing certain factors like how much of a drug gets excreted by the body—the team calculated backward to figure out drug usage. For cocaine, daily consumption averaged between 0.31 and 2.8 grams per 1,000 inhabitants. The researchers say this is in line with estimates from Spain.

The Norwegian study looked only at one wastewater treatment plant that serves much of Oslo and three neighboring areas, but other studies have tracked drug usage over a much larger area. In 2008, researchers collected samples from 96 municipalities in Oregon, accounting for 65 percent of the state’s population. They found that cocaine use was much higher in urban areas whereas methamphetamine was found everywhere.

The Oregon study was only a one-day snapshot of drug habits. But if such a study were maintained over time, sewage epidemiology could be a powerful drug-tracking tool for law enforcement. As the Popular Science article points out, such analyses could allow officials to evaluate the effectiveness of anti-drug campaigns or follow drug supply lines.

The possibility of constant wastewater monitoring may make some people uncomfortable, but I find it fascinating that scientists can track a range of behaviors—from prescription drug use to preferences in cosmetics—with a test tube of sewer water. I wonder what sewage epidemiologists will be looking for next.

Unofficially, the periodic table goes up to element 118. (via Wikimedia commons)

It’s official: Elements 114 and 116 do exist and belong on the periodic table.

Well, when I say “exist,” I really mean “existed.” See, when scientists make them in the lab—by bombarding radioactive plutonium or curium with calcium nuclei—these atoms, the heaviest ever to exist, live for just a fraction of a second before undergoing radioactive decay. The only way to even know that the elements have been created is by studying that decay—measuring the time intervals between each step in the decay process and the energy of the alpha particles produced. (Check out the video below for a good explanation of how the elements were created and how scientists studied them.)

The properties of elements 114 and 116 are unknown, however, and are likely to remain so. “The lifetimes of these things have to be reasonably long so you can study the chemistry—meaning, pushing a minute,” committee chair Paul Karol, of Carnegie Mellon University, told New Scientist.

The committee also evaluated research that claimed to have created elements 113, 115 and 118 in the lab, but the scientists deemed the evidence not yet strong enough to add them to the official periodic table.

Elements 114 and 116 have the unofficial names of ununquadium and ununhexium, but their discoverers will soon be able to submit their own ideas to another committee. “As long as it’s not something really weird, they will probably say it’s fine,” said Karol.

If you were going to name a new element, what would you choose? Tell us in the comments.

A black smoker vent in the Pacific Ocean; inset is an electron micrograph of a pyrite nanoparticle (Credit: University of Delaware)

Deep in the oceans, hydrothermal vents spew superheated water full of dissolved minerals. The vents spawn diverse communities of unique creatures that not only withstand the extreme temperatures and acidity but even depend on the chemicals in the water to live. New research in Nature Geoscience shows that these vents may be having even greater impacts by providing fertilizer for ocean life far away.

Researchers from the University of Delaware and elsewhere traveled to the Lau Basin in the Pacific Ocean and sampled waters from the hydrothermal vents using a remotely operated vehicle. They found nanoparticles of pyrite—a mineral composed of iron and sulfur more commonly known as fool’s gold—1,000 times smaller than the width of a hair. Scientists had known that the waters contained pyrite but thought that the particles were big enough that they quickly settled onto the ocean floor. But these tiny particles don’t do that. They’re small enough that they disperse into the ocean, where they stay suspended. And this type of iron doesn’t oxidize (that is, rust) very quickly, so it can remain in the water even longer, available for the plankton and bacteria that need it.

“As pyrite travels from the vents to the ocean interior and toward the surface ocean, it oxidizes gradually to release iron, which becomes available in areas where iron is depleted so that organisms can assimilate it, then grow,” says study co-author, George Luther of the University of Delaware. “It’s an ongoing iron supplement for the ocean—much as multivitamins are for humans.”

The vents aren’t the only source of iron in the ocean, but some researchers have suggested that they may contribute as much iron as rivers do.

What happens when we send things down a drain? (image courtesy of flickr user mag3737)

If you put something down a drain you shouldn’t have and the drain gets blocked, it’s usually not much more than annoying. But for the people who manage the sewers, blockages in the pipes that go from our homes and businesses to treatment facilities cause bigger problems—sewage spills called “sanitary sewer overflows.” (Yuck!)

One of the major causes of sewer pipe blockages is the formation of hardened, insoluble deposits of fats, oils and grease (FOG); these formations look something like the stalactites in a cave, they have a grainy texture like sandstone, and they adhere strongly to a pipe wall. But little has been known about how they form or even what they are made of.

A group of scientists from North Carolina State University analyzed the contents of these deposits with a technique that uses infrared light to determine the molecular composition of a substance. They were fatty acids, of course, but also calcium. “We found that FOG deposits in sewage collection systems are created by chemical reactions that turn the fatty acids from FOG into, basically, a huge lump of soap,” said N.C. State engineering professor Joel Ducoste, a co-author on the paper, which will be published in Environmental Science & Technology.

The fat and grease break down into glycerol and free fatty acids that then chemically react with calcium present in the sewage system to form these hard deposits. The researchers hope to determine how quickly the deposits form and where the calcium is coming from so that they can then create a model to predict where the blockages might occur and prevent these messy sewer overflows.

Ozone concentrations over the Arctic on March 19, 2010 (left) and 2011 (right), as recorded by the Aura satellite. (NASA image by Rob Simmon, with data courtesy of Ozone Hole Watch.)

When you hear the term “ozone hole” you think about the ozone depletion over Antarctica, and how people in the far south of the Southern Hemisphere have to protect themselves from the Sun. It’s why my friends have to buy hats for their little girl and slather her with sunblock every time she goes outside.

In 1987, countries around the world adopted an ozone-protecting agreement called the Montreal Protocol to phase out ozone-depleting chemicals such as chlorofluorocarbons (CFCs). Concentrations of these chemicals in polar regions have fallen about 10 percent from their peak years before the protocol, and the Antarctic ozone hole has been getting smaller and will disappear by sometime in the middle of this century.

But the announcement this week of record low levels of ozone above the Arctic is a reminder that CFCs and similar chemicals have a long life in the atmosphere, and the problem of ozone depletion isn’t going away anytime soon.

The winds of the polar vortex, which was stronger than usual this year, prevented the mass of air over the North Pole from mixing with mid-latitude air, resulting in low stratospheric temperatures. When sunlight arrived in March, the CFCs (and other chlorine- and bromine-based compounds) went to work breaking down the ozone, destroying 40 percent of the ozone in the Arctic stratosphere. (An average year sees only 25 percent or so of Arctic ozone depleted and 55 percent of Antarctic ozone).

Antarctic weather, and the ozone hole, is fairly predictable, but things are more variable in the Arctic. That means that a big loss from year to year, as with 2010 to 2011, isn’t necessarily something to worry about, but it will also make any efforts to understand Arctic loss more difficult.

“In a changing climate, it is expected that on average stratospheric temperatures cool, which means more chemical ozone depletion will occur,” said Mark Weber, an atmospheric scientist at the University of Bremen. “On the other hand, many studies show that the stratospheric circulation in the northern hemisphere may be enhanced in the future and, consequently, more ozone will be transported from the tropics into high latitudes and reduce ozone depletion.”

The World Meteorological Organization recommends that people living in far northern latitudes pay attention to local UV forecasts. Exposure to UV radiation can lead to cancer, cataracts and damage to the immune system.

Watch a NASA animation of changing Arctic ozone here.

Van Gogh's View of Arles with Irises (1888) (via wikimedia commons)

One of the features of Vincent Van Gogh‘s art that set him apart was his use of bright colors, made possible by the invention of industrial pigments such as chrome yellow. But in the century since, many of these colors, including the bright yellows of his famous sunflowers, have faded, turning brown after exposure to sunlight.

A group of chemists set out to discover what was happening with the paints, with the hope that they might one day be able to reverse the process; their study appears in Analytical Chemistry. They started by artificially aging paint samples taken from historic paint tubes by exposing them to light from a UV lamp for 500 hours. One sample, from a tube that had belonged to Flemish painter Fauvist Rikk Wouters, quickly turned brown. X-ray analysis revealed that the oxidation state of the chromium atoms had changed from Cr(VI) to Cr(III), a more stable form of the atom and one that appears green instead of yellow.

The chemists then applied their X-ray analysis to two Van Gogh paintings, View of Arles with Irises and Bank of the Seine, that reside at the Van Gogh Museum in Amsterdam. That analysis revealed that the change in oxidation state tended to occur when the chromium was mixed with compounds containing barium sulfate. Barium sulfate was a major component in lithopone, a white pigment commonly used during Van Gogh’s time, although there is no record of him using that pigment. The chemists speculate that Van Gogh mixed lithopone into his yellow paint, possibly as an extender to get more use out of it. He may have stretched his paint, but it appears he also lessened how long it would shine so brightly.

The International Year of Chemistry is about to begin

The United Nations has dubbed 2011 the International Year of Chemistry, with the unifying theme “Chemistry—our life, our future.”

The goals of IYC2011 are to increase the public appreciation of chemistry in meeting world needs, to encourage interest in chemistry among young people, and to generate enthusiasm for the creative future of chemistry. The year 2011 will coincide with the 100th anniversary of the Nobel Prize awarded to Madame Marie Curie—an opportunity to celebrate the contributions of women to science. The year will also be the 100th anniversary of the founding of the International Association of Chemical Societies, providing a chance to highlight the benefits of international scientific collaboration.

There will be lectures, conferences and exhibits that examine the role of chemistry in global issues and, of course, a party or two. But what is exciting me the most is all the hands-on experiments for schoolkids around the world, particularly what they are calling a global experiment, “Water: A Chemical Solution,” the world’s biggest chemistry experiment ever.

Millions of schoolkids around the world will perform four experiments in two categories:

Measurement of water quality:
i. pH: students collect data measuring the pH of a water body, using indicator solutions (and pH meters if available).
ii. Salinity: students explore the salinity of their local water body

Water purification:
i. Filtration and disinfection: students will learn how chemistry is used to help provide safe drinking water
ii. Desalination: Students will construct a solar still from household materials and experiment with its use to purify water.

The activities, which can be performed as stand-alone experiments in class or incorporated into a larger curriculum, are not only relevant to kids in every country, but they are also simple enough to be undertaken by children of all ages and even in developing nations where resources may be scarce (although toolkits will be provided). Schools can then upload the results of their experiments to a website (not yet online), which should then provide an interesting data set for anyone interested in water issues.

The IYC2011 kicks off next month with opening ceremonies on January 27 and 28 at the UNESCO headquarters in Paris. I look forward to seeing what the organizers have in store.