For some dropped foods, the five-second rule is about five seconds too long. Wet foods, such as watermelon, slurp up floor germs almost immediately, scientists report online September 2 in Applied and Environmental Microbiology.

Robyn Miranda and Donald Schaffner of Rutgers University in New Brunswick, N.J., tested gummy candy, watermelon and buttered and unbuttered bread by dropping morsels onto various surfaces coated with Enterobacter aerogenes bacteria. Food was left on each surface — stainless steel, ceramic tile, wood and carpet — for time periods ranging from less than a second to five minutes. Afterward, the researchers measured the amount of E. aerogenes on the food, harmless bacteria that share attachment characteristics with stomach-turning Salmonella.

As expected, longer contact times generally meant more bacteria on the food. But the transfer depended on other factors, too. Carpet, for instance, was less likely to transfer germs than the other surfaces. Gummy candies, particularly those on carpet, stayed relatively clean. But juicy watermelon quickly picked up lots of bacteria from all surfaces in less than a second. These complexities, the authors write, mean that the five-second rule is probably a rule worth dropping.

Shock waves may have jolted the infant cosmos. Clumpiness in the density of the early universe piled up into traveling waves of abrupt density spikes, or shocks, like those that create a sonic boom, scientists say.

Although a subtle effect, the shock waves could help scientists explain how matter came to dominate antimatter in the universe. They also could reveal the origins of the magnetic fields that pervade the cosmos. One day, traces of these shocks, in the form of gravitational waves, may even be detectable.
Scientists believe that the early universe was lumpy — with some parts denser than others. These density ripples, known as perturbations, serve as the seeds of stars and galaxies. Now, scientists have added a new wrinkle to this picture. As the ripples rapidly evolved they became steeper, like waves swelling near the shore, until eventually creating shocks analogous to a breaking wave. As a shock passes through a region of the universe, the density changes abruptly, before settling back down to a more typical, slowly varying density. “Under the simplest and most conservative assumptions about the nature of the universe coming out of the Big Bang, these shocks would inevitably form,” says cosmologist Neil Turok of the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

In a paper published September 21 in Physical Review Letters, Turok and Ue-Li Pen of the Canadian Institute for Theoretical Astrophysics in Toronto performed calculations and simulations that indicate shocks would form less than one ten-thousandth of a second after the Big Bang.

“It’s interesting that nobody’s actually noticed that before,” says cosmologist Kevork Abazajian of the University of California, Irvine. “It’s an important effect if it actually happened.”

These shocks, Turok and Pen found, could produce magnetic fields, potentially pointing to an answer to a cosmological puzzle. Magnetic fields permeate the Milky Way and other parts of the cosmos, but scientists don’t know whether they sprang up just after the birth of the universe or much later, after galaxies had formed. Shock waves could explain how fields might have formed early on. When two shocks collide, they create a swirling motion, sending electrically charged particles spiraling in a way that could generate magnetic fields.
Shocks could also play a role in explaining why the universe is made predominantly of matter. The Big Bang should have yielded equal amounts of matter and antimatter; how the cosmic scales were tipped in matter’s favor is still unexplained. Certain theorized processes could favor the production of matter, but it’s thought they could happen only if temperatures in the universe are uneven. Shocks would create abrupt temperature jumps that would allow such processes to occur.

Scientists may be able to verify these calculations by detecting the gravitational waves that would have been produced when shocks collided. Unfortunately, the gravitational ripples produced would likely be too small to detect with current technologies. But under certain theories, in which large density fluctuations create regions so dense that they would collapse into black holes, the gravitational waves from shocks would be detectable in the near future. “If there was anything peculiar in the early universe, you would actually be able to detect this with upcoming technology,” says Abazajian. “I think that is remarkable.”

Like many abandoned mines, the Eureka uranium mine in northern Spain is a maze of long, dank tunnels. Water seeping down the walls carries dissolved substances that percolated through rocks overhead. As the water evaporates into the tunnels’ cool air, some of those dissolved ingredients combine to make new substances in solid form.

“The mine is a crystallization factory of weird minerals,” says Jordi Ibáñez-Insa, a physicist at the Institute of Earth Sciences Jaume Almera in Barcelona.
Including the uranium-bearing ores that attracted miners to Eureka in the first place, scientists visiting the mine have cataloged 61 different minerals — solids that have a distinct chemical recipe and arrangement of atoms. The latest find, called abellaite, is a rarity that grows in small pincushions of tiny crystalline needles about 40 to 50 micrometers long. Discovered in July 2010, the mineral has been found only on the walls of a 3-meter-long stretch of one tunnel, says Ibáñez-Insa.

Abellaite is uncommon in another sense: It contains carbon. Of the 5,161 minerals characterized by scientists and recognized by the International Mineralogical Association, just 8 percent, or 416, include carbon.

The Carbon Mineral Challenge, launched last December and running until September 2019, exhorts researchers to scour the landscape — and their museum drawers — for unknown carbon-bearing minerals. In a recent analysis, scientists estimate that there are at least 548 carbon minerals on Earth. That means well over 100 are waiting to be noticed.

The analysis, published in the April American Mineralogist, even provides clues about where scientists and rock hounds should look and what recipes and atomic arrangements such minerals might have.
The hunt for carbon minerals is much more than stamp (or rock) collecting. The challenge aims to identify minerals that could help tell the story of the planet’s carbon and water cycles — past and present. Besides having a specific recipe and structure, minerals form only in certain conditions (on Earth and elsewhere), making them keen chroniclers of the environments that existed at the time and place they formed, as well as the conditions since then.

A census of minerals
A few minerals are, forgive the phrase, as common as dirt. Of the more than 5,000 recognized minerals, about 100 have been reported by geologists and amateur collectors at more than 1,000 sites worldwide. Many more are very rare: At least 1,000 minerals have been found in only one locale, says Robert Hazen, a geophysicist at the Carnegie Institution for Science in Washington, D.C. More than half of the world’s minerals have been found at five or fewer locations.

Not every mineral on Earth has been discovered, of course. But by analyzing a massive database of known minerals and how common or rare they are, scientists can use a standard statistical tool to estimate the number of minerals yet to be uncovered. Hazen and his colleagues suggest in the August 2015 issue of Mathematical Geosciences that there are at least 1,500 undiscovered minerals out there. About 140 of those minerals contain carbon, the team predicted in the follow-on analysis published in April.

Both professional mineralogists and amateur collectors can participate in the Carbon Mineral Challenge, but any potential discoveries have to survive the strict screening process of the International Mineralogical Association, which Ibáñez-Insa and a raft of colleagues navigated for abellaite. (The mineral was approved in December 2015.) The researchers submitted a portfolio of data — the sample’s appearance, chemical makeup, arrangement of atoms, color, hardness, transparency, fluorescence, a proposed name and more — to the IMA’s Commission on New Minerals, Nomenclature and Classification.

Promising places
In the search for hidden carbon-bearing minerals, scientists and rock hounds aspiring to geologic fame should visit these locales (or analyze samples already collected there).

Tap the map to explore carbon mineral “hot spots” around the world.
A few dozen new minerals are recognized each year, says Hans-Peter Schertl, a mineralogist at Ruhr University in Bochum, Germany, and an IMA officer. Approval can be straightforward, or it can drag out for months or longer, especially if additional data are required, Schertl says. One strict requirement is that a sample be natural, not lab-made or a result of human interference. Thus, any unusual crystals that grow on the surfaces of rocks that were pulled from a mine and then dumped nearby and exposed to the elements wouldn’t qualify as a mineral, he notes, “Those would just be pretty crystals.”

Oddly, the “natural sample” requirement long prevented official recognition of what is purported to be the most common mineral on Earth. Bridgmanite, an iron- and magnesium-rich silicate, received the IMA seal of approval only in 2014 (SN: 1/10/15, p. 4). Estimated to make up a whopping 38 percent of the planet’s volume, bridgmanite can exist only at the high pressures found between 660 and 2,900 kilometers below Earth’s surface — too deep to dig up. Scientists had long studied lab-made samples but hadn’t found a natural bit of the mineral until earlier this decade in a meteorite that landed in Australia in 1879.

Where to look
In their analysis published in April, Hazen and colleagues included general recipes for a variety of Earth’s yet-to-be-discovered carbon minerals. One formula — a complex mix of sodium, lead and carbonate and hydroxyl ions, written scientifically as NaPb2(CO3)2(OH) — matches abellaite from the Spanish mine. Bingo. One more carbon mineral in the bag.

Many of those “missing” minerals will be very similar to known forms, with combinations that differ by only a single element — swapping out a magnesium atom for a calcium atom in the recipe for a known mineral, for example, or a sodium atom for a potassium atom.

“The chemical formula tells you a lot about the conditions that a mineral forms in,” says Daniel Hummer, a geochemist at Southern Illinois University in Carbondale and lead scientist for the Carbon Mineral Challenge. It also suggests that existing minerals that have a very similar formula can, in many cases, serve as a guide for what the missing minerals might look like, in terms of the colors or shapes of their crystals.

In fact, similarities could be so strong that a mineral might be overlooked because it looks so much like a known, or even common, mineral. “It’s possible that some of these missing minerals are hiding in plain sight,” Hummer notes.

If not camouflaged, some carbon minerals may simply be so scarce that they’ve never been encountered. In June in American Mineralogist, Hazen and environmental scientist Jesse Ausubel of Rockefeller University in New York City discuss several reasons why minerals can be rare — so rare, in fact, that the entire world’s supply might fit into a thimble, Hazen says.

First, a mineral might form or remain stable only in extremely unusual combinations of temperature, pressure and pH. The mineral hatrurite (Ca3SiO5), for example, forms only at temperatures above 1,250° Celsius and only in the absence of aluminum, the third most common element in Earth’s crust. Hatrurite was first found in Israel, in an ancient limestone deposit that was probably exposed to intense heat generated when hydrocarbons in nearby sediments burned.

Second, a mineral might include chemical elements that are rare to begin with and even rarer in combination. Examples include swedenborgite (which contains the scarce combination of beryllium and antimony) and any mineral that includes tellurium, which on average is found in Earth’s crust at concentrations of 5 parts per billion.

Third, a mineral may be exceptionally ephemeral. Some are so hygroscopic, or humidity-absorbing, that they pull moisture from the air and dissolve themselves, Hazen says. Hygroscopic minerals have to be collected or observed in the field as they form and before they disappear. Then there are the minerals that form in conditions so remote or harsh that scientists hardly ever get near them (think deep-sea hydrothermal vents or active volcanoes).

Some minerals present more than one of these challenges. Consider fingerite, Cu11O2(VO4)6, an unstable shiny black mineral that forms only at high temperatures and includes the rare combination of copper and vanadium. This exceedingly rare mineral is known only from samples recovered from rocks near heat-belching fissures and holes atop El Salvador’s Izalco volcano.

There are less hostile places to search for new minerals, though. Fourteen sites worldwide, including mines, have each given up 20 or more carbon minerals, Hazen says. Scientists could revisit those 14 sites and look for more unrecognized minerals, he notes. Or they could simply take a closer look at or perform additional tests on samples already collected from such locales.
Or researchers could target areas where ephemeral minerals could be expected to form, if ever so briefly. For example, calcium carbide — a substance produced on an industrial scale to create acetylene for miner’s lamps — reacts so quickly with water that it hasn’t been found in a natural setting. But small, short-lived quantities might be produced when lightning strikes near rocks containing both limestone and coal (admittedly, a pretty hostile situation).

There’s no reason to be limited by the 14 promising locations. Scientists found the yellowish-white crystals of tinnunculite (C5H4N4O3•2H2O), mineral just recognized in December, in an unexpected milieu: inside the residue of bird poop that had landed on extremely hot rocks overlying an underground coal fire in northwestern Russia. The elevated temperatures drive the crystallization of uric acid in the excrement, the researchers say.

The exotic mineral was dubbed tinnunculite to honor the European kestrel (Falco tinnunculus), whose indispensable contribution to mineralogy cannot be denied.

For his part, Ibáñez-Insa plans to spend more time at Spain’s Eureka mine. Although the site’s uranium ores are no longer worth extracting, scientific treasures akin to abellaite may still lie undiscovered. “I’m pretty sure,” he says, “we’ll find some more new minerals there.”
This article appears in the October 15, 2016, issue of Science News with the headline, “Digging Carbon: A new challenge has scientists searching for dozens of unknown, beguiling crystals.”

Deep-sea viruses aren’t just dealers of disease; they’re crucial players in Earth’s nutrient cycles. In marine sediments, virus assassinations of single-celled life-forms called archaea play a much larger role in carbon and other chemical cycles than previously thought, new research suggests. For instance, those microbial murders release as much as 500 million metric tons of carbon annually worldwide, researchers report online October 12 in Science Advances.

Viruses are a major killer of bacteria and archaea in the deep sea, busting open infected cells like water balloons and spewing the cells’ innards. To find the relative number of massacred microbes, marine ecologist Roberto Danovaro of Polytechnic University of Marche in Ancona, Italy, and colleagues studied the spilled guts of the viruses’ victims.

Tallying the number of archaeal versus bacterial genes released from the carnage in more than 480 sediment samples, the researchers discovered that viruses kill archaea disproportionately more often than bacteria. Despite making up on average about 12 percent of the microbial population in the top 50 centimeters of sediment, archaea accounted for up to one-third of the total biomass killed by viruses, Danovaro and colleagues report. The researchers do not speculate on why archaea were such frequent targets. Those deaths were not in vain, though: Archaea corpses supply nutrients such as carbon that help sustain other life-forms.

When the body’s internal sense of time doesn’t match up with outside cues, people can suffer, and not just from a lack of sleep.

Such ailments are similar in a way to motion sickness — the queasiness caused when body sensations of movement don’t match the external world. So scientists propose calling time-related troubles, which can afflict time-zone hoppers and people who work at night, “circadian-time sickness.” This malady can be described, these scientists say, with a certain type of math.
The idea, to be published in Trends in Neurosciences, is “intriguing and thought-provoking,” says neuroscientist Samer Hattar of Johns Hopkins University. “They really came up with an interesting idea of how to explain the mismatch.”

Neuroscientist Raymond van Ee of Radboud University in the Netherlands and colleagues knew that many studies had turned up ill effects from an out-of-whack circadian clock. Depression, metabolic syndromes and memory troubles have been found alongside altered daily rhythms. But despite these results, scientists don’t have a good understanding of how body clocks work, van Ee says.

Van Ee and colleagues offer a new perspective by using a type of math called Bayesian inference to describe the circadian trouble. Bayesian inference can be used to describe how the brain makes and refines predictions about the world. This guesswork relies on the combination of previous knowledge and incoming sensory information (SN: 5/28/16, p. 18). In the case of circadian-time sickness, these two cues don’t match up, the researchers propose.

Some pacemaking nerve cells respond directly to light, allowing them to track the outside environment. Other pacemakers don’t respond to light but rely on internal signals instead. Working together, these two groups of nerve cells, without any supervision from a master clock, can set the body’s rhythms. But when the two timekeepers arrive at different conclusions, the conflict muddies the time readout in the body, leading to a confused state that could cause poor health outcomes, van Ee and colleagues argue.

This description of circadian-time sickness is notable for something it leaves out — sleep. While it’s true that shifted sleep cycles can cause trouble, a misalignment between internal and external signals may cause problems even when sleep is unaffected, the researchers suggest. That runs counter to the simple and appealing idea that out-of-sync rhythms cause sleep deprivation, which in turn affects the body and brain. That idea “was totally linear and beautiful,” Hattar says. “But once you start looking very carefully at the data in the field, you find inconsistencies that people ignored.”
It’s difficult to disentangle sleep from circadian misalignments, says neuroscientist Ilia Karatsoreos of Washington State University in Pullman. Still, research by him and others has turned up detrimental effects from misaligned circadian rhythms — even when sleep was normal. This new paper helps highlight why “it is important to be able to study and understand the contribution of each,” he says.

The concept of circadian-time sickness is an idea that awaits testing, Karatsoreos cautions. Yet it’s a “useful way for us to talk about this general problem, if only for the fact that it’s a way of thinking that I’ve really never seen before.”