Posts Tagged ‘water’

By Emily Underwood

Viewed under a microscope, your tongue is an alien landscape, studded by fringed and bumpy buds that sense five basic tastes: salty, sour, sweet, bitter, and umami. But mammalian taste buds may have an additional sixth sense—for water, a new study suggests. The finding could help explain how animals can tell water from other fluids, and it adds new fodder to a centuries-old debate: Does water have a taste of its own, or is it a mere vehicle for other flavors?

Ever since antiquity, philosophers have claimed that water has no flavor. Even Aristotle referred to it as “tasteless” around 330 B.C.E. But insects and amphibians have water-sensing nerve cells, and there is growing evidence of similar cells in mammals, says Patricia Di Lorenzo, a behavioral neuroscientist at the State University of New York in Binghamton. A few recent brain scan studies also suggest that a region of human cortex responds specifically to water, she says. Still, critics argue that any perceived flavor is just the after-effect of whatever we tasted earlier, such as the sweetness of water after we eat salty food.

“Almost nothing is known” about the molecular and cellular mechanism by which water is detected in the mouth and throat, and the neural pathway by which that signal is transmitted to the brain, says Zachary Knight, a neuroscientist at the University of California, San Francisco. In previous studies, Knight and other researchers have found distinct populations of neurons within a region of the brain called the hypothalamus that can trigger thirst and signal when an animal should start and stop drinking. But the brain must receive information about water from the mouth and tongue, because animals stop drinking long before signals from the gut or blood could tell the brain that the body has been replenished, he says.

In an attempt to settle the debate, Yuki Oka, a neuroscientist at the California Institute of Technology in Pasadena, and colleagues searched for water-sensing taste receptor cells (TRCs) in the mouse tongue. They used genetic knockout mice to look for the cells, silencing different types of TRCs, then flushing the rodents’ mouths with water to see which cells responded. “The most surprising part of the project” was that the well-known, acid-sensing, sour TRCs fired vigorously when exposed to water, Oka says. When given the option of drinking either water or a clear, tasteless, synthetic silicone oil, rodents lacking sour TRCs took longer to choose water, suggesting the cells help to distinguish water from other fluids.

Next, the team tested whether artificially activating the cells, using a technique called optogenetics, could drive the mice to drink water. They bred mice to express light-sensitive proteins in their acid-sensing TRCs, which make the cells fire in response to light from a laser. After training the mice to drink water from a spout, the team replaced the water with an optic fiber that shone blue light on their tongues. When the mice “drank” the blue light, they acted as though they were tasting water, Oka says. Some thirsty mice licked the light spout as many as 2000 times every 10 minutes, the team reports this week in Nature Neuroscience.

The rodents never learned that the light was just an illusion, but kept drinking long after mice drinking actual water would. That suggests that although signals from TRCs in the tongue can trigger drinking, they don’t play a role in telling the brain when to stop, Oka says.

More research is needed to precisely determine how the acid-sensing taste buds respond to water, and what the mice experience when they do, Oka says. But he suspects that when water washes out saliva—a salty, acidic mucus—it changes the pH within the cells, making them more likely to fire.

The notion that one of the ways animals detect water is by the removal of saliva “makes a lot of sense,” Knight says. But it is still only one of many likely routes for sensing water, including temperature and pressure, he adds.

The “well-designed, intriguing” study also speaks to a long-standing debate over the nature of taste, Di Lorenzo says. When you find a counterexample to the dominant view that there are only five basic taste groups, she says, “it tells you you need to go back to the drawing board.”

http://www.sciencemag.org/news/2017/05/scientists-discover-sixth-sense-tongue-water

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by David Z. Morris

A new device, developed by researchers at UC Berkeley and MIT, promises to bring clean drinking water to remote areas by drawing it directly from the air. Though the device is currently only a prototype, its early results appear extremely promising.

The device, which calls to mind the “moisture vaporators” Luke Skywalker oversaw in his youth, was developed in collaboration between chemist Omar Yaghi and mechanical engineer Evelyn Wang. It relies on a special material combining zirconium and adipic acid into what’s known as a metal-organic framework. At night, the material collects water molecules from the air. Then, during the day, sunlight causes it to release the water into a condenser.

In early tests, the device has been able to produce nearly three liters of water over 12 hours for every kilogram of the zirconium-acid material, even in very dry regions. Speaking to Science, an expert not involved in the project called the results “a significant proof of concept.”

There is one obstacle to wide deployment of the devices—the high cost of the key zirconium material. But the researchers say they’ve already had some success using cheaper aluminum instead.

Yaghi says the device would allow for taking water supplies “off-grid.” That invites a comparison to the global spread of cell phones, which, by circumventing the need to lay expensive wires, have proven more accessible in developing nations than wired phones. Their spread has had profound effects on global agriculture, education, and governance.

But the impact of a device that produces drinkable clean water, without the need for expensive pipes, filtration facilities, or even power, could be even bigger. According to the World Health Organization, 1 in 10 people worldwide lack access to clean water, and 88% of all disease in the developing world has been estimated to be caused by unsafe drinking water. For lack of water, millions die each year of cholera, malaria, diarrhea, and malnutrition. Not surprisingly, a 2009 study found that GDP growth correlated strongly with access to clean water.

Issues of water access aren’t limited to developing nations, either. Even in the U.S., clean, safe water has been a hot button issue at the center of outrage over lead contamination in Flint, Michigan and other cities and concerns over California’s drought woes. Fears the Missouri River could be contaminated by a leak from the Dakota Access Pipeline inspired the protest slogan “water is life.”

http://fortune.com/2017/04/16/drinking-water-technology/

Peña Blanca is a small agricultural community 300 km north of Santiago.

In this arid coastal region, ‘fog catchers’ — large nets strung up in areas with thick fog and high winds — are used to collect water.

The technique was pioneered in Chile in the 1950s. The fog is pushed through fine mesh where it condenses, trickles down, and gets collected below. It’s a cheap, effective, and clean way to source water.

The nets harvest precious water for crops and animals: 140 square meters provide 840 liters of water per day, shared among 85 landowners.

“Water shortage is a worldwide problem and we are not oblivious to it,” says Daniel Rojas, community leader. “It rains less and less, there is a lack of vegetation, fewer crops and people are affected in every sense. But here we have a natural resource that wasn’t being exploited.”

The ‘camanchaca’ is a thick coastal fog which rolls in most days. It blocks the sun, but the low visibility and wind is welcomed by the locals.

The Dar Si Hmad project in Morocco is significantly bigger, and uses next generation technology. The water collected here is clean enough to drink. And there are plans to use newer nets which are more efficient, doubling the amount of water they currently collect.

“They call me the fog queen,” laughs Dr Jamila Bargach.

She has good reason to smile. As director of the world’s largest fog catching project, she picked up an award at the 2016 UN climate conference in Marrakech for the work carried out by her women-led NGO.

“Our new nets have a mean average of 22 liters per square meter, which will service about 1,300 people, about 13 villages,” she says.

The fog catchers have changed the lives of women in the Sahara, who previously scheduled their days around the chore of fetching and carrying water for their families.

“The average time is 3 hours per day to get your basic 30 liters. This is becoming even more difficult because you have to walk further with the consequences of climate change: desertification and the rising temperatures,” says Dr Bargach.

“So where there’s fog, we can harness it for the community, store it when it’s needed, and then use it later, instead of looking for very expensive and fossil-based solutions like desalinizing water, or digging more bore holes, looking for even deeper aquifers.”

As with any project, it needs to be economically viable. And that’s one of the reasons Dar Si Hmad charges for its water.

“We do charge for the water, otherwise how will we keep up with the maintenance? We have aligned the prices with government prices, and we have taken 20 percent off, because we’re dealing with very poor communities. But let me tell you one thing. Even with water, the moment it becomes free, it will lose its value.”

In Chile the economic opportunities are a little different. Peña Blanca now boasts an award-winning ale from the Atrapaniebla brewery.

Marcos Carcuro and his brother have their own nets alongside those belonging to the village.

“At first they told us it was a crazy idea to brew beer from clouds”, says Carcuro. “But later, seeing the results of our first prototypes, we realized that it was going to be a better product than those made with regular water.”

Where the weather suits, and when maintenance costs are met, fog catchers provide a lifeline in vulnerable communities across the world. From Chile to Morocco, it’s a proven sustainable and scalable solution to water scarcity.

http://www.cnn.com/2016/12/28/world/eco-solutions-fog-catchers/index.html

By Helen Thomson

“When the tide came in, these kids started swimming. But not like I had seen before. They were more underwater than above water, they had their eyes wide open – they were like little dolphins.”

Deep in the island archipelagos on the Andaman Sea, and along the west coast of Thailand live small tribes called the Moken people, also known as sea-nomads. Their children spend much of their day in the sea, diving for food. They are uniquely adapted to this job – because they can see underwater. And it turns out that with a little practice, their unique vision might be accessible to any young person.

In 1999, Anna Gislen at the University of Lund, in Sweden was investigating different aspects of vision, when a colleague suggested that she might be interested in studying the unique characteristics of the Moken tribe. “I’d been sitting in a dark lab for three months, so I thought, ‘yeah, why not go to Asia instead’,” says Gislen.

Gislen and her six-year old daughter travelled to Thailand and integrated themselves within the Moken communities, who mostly lived on houses sat upon poles. When the tide came in, the Moken children splashed around in the water, diving down to pick up food that lay metres below what Gislen or her daughter could see. “They had their eyes wide open, fishing for clams, shells and sea cucumbers, with no problem at all,” she says.

Gislen set up an experiment to test just how good the children’s underwater vision really was. The kids were excited about joining in, says Gislen, “they thought it was just a fun game.”

The kids had to dive underwater and place their heads onto a panel. From there they could see a card displaying either vertical or horizontal lines. Once they had stared at the card, they came back to the surface to report which direction the lines travelled. Each time they dived down, the lines would get thinner, making the task harder. It turned out that the Moken children were able to see twice as well as European children who performed the same experiment at a later date.

What was going on? To see clearly above land, you need to be able to refract light that enters the eye onto the retina. The retina sits at the back of the eye and contains specialised cells, which convert the light signals into electrical signals that the brain interprets as images.

Light is refracted when it enters the human eye because the outer cornea contains water, which makes it slightly denser than the air outside the eye. An internal lens refracts the light even further.

When the eye is immersed in water, which has about the same density as the cornea, we lose the refractive power of the cornea, which is why the image becomes severely blurred.

Gislen figured that in order for the Moken children to see clearly underwater, they must have either picked up some adaption that fundamentally changed the way their eyes worked, or they had learned to use their eyes differently under water.

She thought the first theory was unlikely, because a fundamental change to the eye would probably mean the kids wouldn’t be able to see well above water. A simple eye test proved this to be true – the Moken children could see just as well above water as European children of a similar age.

It had to be some kind of manipulation of the eye itself, thought Gislen. There are two ways in which you can theoretically improve your vision underwater. You can change the shape of the lens – which is called accommodation – or you can make the pupil smaller, thereby increasing the depth of field.

Their pupil size was easy to measure – and revealed that they can constrict their pupils to the maximum known limit of human performance. But this alone couldn’t fully explain the degree to which their sight improved. This led Gislen to believe that accommodation of the lens was also involved.

“We had to make a mathematical calculation to work out how much the lens was accommodating in order for them to see as far as they could,” says Gislen. This showed that the children had to be able to accommodate to a far greater degree than you would expect to see underwater.

“Normally when you go underwater, everything is so blurry that the eye doesn’t even try to accommodate, it’s not a normal reflex,” says Gislen. “But the Moken children are able to do both – they can make their pupils smaller and change their lens shape. Seals and dolphins have a similar adaptation.”

Gislen was able to test a few Moken adults in the same way. They showed no unusual underwater vision or accommodation – perhaps explaining why the adults in the tribe caught most of their food by spear fishing above the surface. “When we age, our lenses become less flexible, so it makes sense that the adults lose the ability to accommodate underwater,” says Gislen.

Gislen wondered whether the Moken children had a genetic anomaly to thank for their ability to see underwater or whether it was just down to practice. To find out, she asked a group of European children on holiday in Thailand, and a group of children in Sweden to take part in training sessions, in which they dived underwater and tried to work out the direction of lines on a card. After 11 sessions across one month, both groups had attained the same underwater acuity as the Moken children.

“It was different for each child, but at some point their vision would just suddenly improve,” says Gislen. “I asked them whether they were doing anything different and they said, ‘No, I can just see better now’.”

She did notice, however, that the European kids would experience red eyes, irritated by the salt in the water, whereas the Moken children appeared to have no such problem. “So perhaps there is some adaptation there that allows them to dive down 30 times without any irritation,” she says.

Gislen recently returned to Thailand to visit the Moken tribes, but things had changed dramatically. In 2004, a tsunami created by a giant earthquake within the Indian Ocean destroyed much of the Moken’s homeland. Since then, the Thai government has worked hard to move them onto the land, building homes that are further inland and employing members of the tribe to work in the National Park. “It’s difficult,” says Gislen. “You want to help keep people safe and give them the best parts of modern culture, but in doing so they lose their own culture.”

In unpublished work, Gislen tested the same kids that were in her original experiment. The Moken children, now in their late teens, were still able to see clearly underwater. She wasn’t able to test many adults as they were too shy, but she is certain that they would have lost the ability to see underwater as they got older. “The adult eye just isn’t capable of that amount of accommodation,” she says.

Unfortunately, the children in Gislen’s experiments may be the last of the tribe to possess the ability to see so clearly underwater. “They just don’t spend as much time in the sea anymore,” she says, “so I doubt that any of the children that grow up these days in the tribe have this extraordinary vision.”

http://www.bbc.com/future/story/20160229-the-sea-nomad-children-who-see-like-dolphins


Scientists have successfully developed a method of producing electricity from seawater, with help from the Sun. Instead of harvesting hydrogen, the new photoelectrochemical cell produces hydrogen peroxide for electricity.

Researchers at Osaka University found a way to turn seawater—one of the most abundant resources on Earth—into hydrogen peroxide (H2O2) using sunlight, which can then be used to generate electricity in fuel cells. This adds to the ever growing number of existing alternative energy options as the world continues to move towards green energy.

“Utilization of solar energy as a primary energy source has been strongly demanded to reduce emissions of harmful and/or greenhouse gases produced by burning fossil fuels. However, large fluctuation of solar energy depending on the length of the daytime is a serious problem. To utilize solar energy in the night time, solar energy should be stored in the form of chemical energy and used as a fuel to produce electricity,” the researchers wrote in their paper.

Previous technologies focused on splitting the molecules of pure water to harvest hydrogen.

As previously mentioned, the new research, instead of harvesting hydrogen from pure water, turns seawater into hydrogen peroxide. Gaseous hydrogen production from pure water has a lower solar energy conversion and is much harder to store, whereas the team notes, “H2O2 can be produced as an aqueous solution from water and O2 in the air.”

It is also much easier and safer to store and transport in higher densities, compared to highly compressed hydrogen gas.

There are other methods of producing H2O2, but they are impractical in that the processes themselves require a lot of energy, essentially defeating the purpose. This is the first time someone developed a photocatalytic method efficient enough to make H2O2 use in fuel cells viable.

The process involves a new photoelectrochemical cell developed to produce H2O2 when sunlight illuminates the photocatalyst, which then absorbs photons and initiates chemical reactions with the energy, resulting in H2O2.

A test conducted for 24 hours shows that the H2O2 concentration in seawater reached about 48mM (millimolar), compared to 2mM in pure water. Researchers found that this was made possible by seawater’s negatively charged chlorine enhancing the photocatalysis.

That said, this method isn’t yet as good as other solar power processes, but it’s a start. Researchers aim to improve efficiency with better materials and lower costs.

“In the future, we plan to work on developing a method for the low-cost, large-scale production of H2O2 from seawater,” Fukuzumi said. “This may replace the current high-cost production of H2O2 from H2 (from mainly natural gas) and O2.”

http://futurism.com/theres-a-new-way-to-generate-power-using-seawater/

Through vegetables and fruits, the drugs that we flush down the drain are returning to us.

In a randomized, single-blind pilot study, researchers found that anticonvulsive epilepsy drug carbamazepine, which is released in urine, can accumulate in crops irrigated with recycled water—treated sewage—and end up in the urine of produce-eaters not on the drugs. The study, published Tuesday in Environmental Science & Technology, is the first to validate the long-held suspicion that pharmaceuticals may get trapped in infinite pee-to-food-to-pee loops, exposing consumers to drug doses with unknown health effects.

While the amounts of the drug in produce-eater’s pee were four orders of magnitude lower than what is seen in the pee of patients purposefully taking the drugs, researchers speculate that the trace amounts could still have health effects in some people, such as those with a genetic sensitivity to the drugs, pregnant women, children, and those who eat a lot of produce, such as vegetarians. And with the growing practice of reclaiming wastewater for crop irrigation—particularly in places that face water shortages such as California, Israel, and Spain—the produce contamination could become more common and more potent, the authors argue.

“The potential for unwitting exposure of consumers to contaminants via this route is real,” the authors wrote, adding that their study provides real world data that proves exposure occurs.

For the study, researchers recruited 34 healthy adults—excluding vegetarians, vegans, and people who take carbamazepine. The participants were all from Israel, where farmers use reclaimed water for 50 percent of the country’s irrigation needs. California, which grows a large portion of US produce, currently uses reclaimed water for six percent of its irrigation needs, but is looking to increase its usage.

First, the researchers measured what was in each participant’s pee, then randomly assigned them to one of two groups. While each participant got a big basket of produce to eat over one week and another basket for a second week, the contents varied depending on their group. Those in group one unknowingly started off with produce irrigated with reclaimed water and then got a batch irrigated with fresh water for the second week. Group two started with produce irrigated with fresh water, then were switched to crops bought at a local grocery store. (The authors admit that they meant to switch the second group to produce grown with reclaimed water for that second week, but they ran out.) The researchers weren’t sure what type of water was used to grow the grocery store produce, but they assumed it was a mix.

Throughout the two weeks, researchers sampled each participant’s urine, looking for carbamazepine and its metabolites—forms of the drug that have been modified in the human body.

At the start, the participants had mixed levels of carbamazepine in their urine, with ~38 percent having undetectable amounts, ~35 percent having detectable amounts that were too little to quantify, and ~26 having low but quantifiable amounts. After the first week, all of the participants in the first group, which noshed on produce irrigated with reclaimed water, had quantifiable amounts of the drug and its metabolites in their urine—some of the amounts hiked up by more than ten-fold from the start. Those in group two, however, didn’t change from their initial measurements.

In the second week, after the veggie swap, the levels of carbamazepine dropped back down to baseline levels in group one participants. Drug levels in participants in group two stayed about the same in the second week, despite some of the grocery store produce testing positive for carbamazepine.

Both of those findings—that drug levels can quickly drop after exposure and the mixed supermarket food didn’t alter levels—is relatively good news for public health, the authors note. Still, the unintentional drug doses in food are a concern worth more attention by the public health community, the authors conclude. Previous studies have found a variety of drugs in crops, including cholesterol medications, caffeine, and triclosan.

Environmental Science & Technology, 2015. DOI: 10.1021/acs.est.5b06256 (About DOIs).

Thanks to Kebmodee for bringing this to the It’s Interesting community.


The ocean there is thought to extend to 10 times the depth of Earth’s oceans.

A salty ocean is lurking beneath the surface of Jupiter’s largest moon, Ganymede, scientists using the Hubble Space Telescope have found.

The ocean on Ganymede—which is buried under a thick crust of ice—could actually harbor more water than all of Earth’s surface water combined, according to NASA officials. Scientists think the ocean is about 60 miles (100 kilometers) thick, 10 times the depth of Earth’s oceans, NASA added. The new Hubble Space Telescope finding could also help scientists learn more about the plethora of potentially watery worlds that exist in the solar system and beyond.

“The solar system is now looking like a pretty soggy place,” said Jim Green, NASA’s director of planetary science. Scientists are particularly interested in learning more about watery worlds because life as we know it depends on water to thrive.

Scientists have also found that Ganymede’s surface shows signs of flooding. Young parts of Ganymede seen in a video map may have been formed by water bubbling up from the interior of the moon through faults or cryo-volcanos at some point in the moon’s history, Green said.

Scientists have long suspected that there was an ocean of liquid water on Ganymede—the largest moon in the solar system, at about 3,273 miles (5,268 kilometers) across—has an ocean of liquid water beneath its surface. The Galileo probe measured Ganymede’s magnetic field in 2002, providing some data supporting the theory that the moon has an ocean. The newly announced evidence from the Hubble telescope is the most convincing data supporting the subsurface ocean theory yet, according to NASA.

Scientists used Hubble to monitor Ganymede’s auroras, ribbons of light at the poles created by the moon’s magnetic field. The moon’s auroras are also affected by Jupiter’s magnetic field because of the moon’s proximity to the huge planet.

When Jupiter’s magnetic field changes, so does Ganymede’s. Researchers were able to watch the two auroras “rock” back and forth with Hubble. Ganymede’s aurora didn’t rock as much as expected, so by monitoring that motion, the researchers concluded that a subsurface ocean was likely responsible for dampening the change in Ganymede’s aurora created by Jupiter.

“I was always brainstorming how we could use a telescope in other ways,” Joachim Saur, geophysicist and team leader of the new finding, said in a statement. “Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon’s interior.”

Hunting for auroras on other worlds could potentially help identify water-rich alien planets in the future, Heidi Hammel, executive vice president of the Association of Universities for Research in Astronomy, said during the teleconference. Scientists might be able to search for rocking auroras on exoplanets that could potentially harbor water using the lessons learned from the Hubble observations of Ganymede.

Astronomers might be able to detect oceans on planets near magnetically active stars using similar methods to those used by Saur and his research team, Hammel added.

“By monitoring auroral activity on exoplanets, we may be able to infer the presence of water on or within an exoplanet,” Hammel said. “Now, it’s not going to be easy—it’s not as easy as Ganymede and Jupiter, and that wasn’t easy. It may require a much larger telescope than Hubble, it may require some future space telescope, but nevertheless, it’s a tool now that we didn’t have prior to this work that Joachim and his team have done.”

Jupiter’s moons are popular targets for future space missions. The European Space Agency is planning to send a probe called JUICE—short for JUpiter ICy moons Explorer—to Jupiter and its moons in 2022. JUICE is expected to check out Europa, Callisto and Ganymede during its mission. NASA also has its eye on the Jupiter system. Officials are hoping to send a probe to Europa by the mid-2020s.

NASA will also celebrate the Hubble telescope’s 25th anniversary this year.

“This discovery marks a significant milestone, highlighting what only Hubble can accomplish,” John Grunsfeld, assistant administrator of NASA’s Science Mission, said in the same statement. “In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth.”

http://www.scientificamerican.com/article/jupiter-s-moon-ganymede-has-a-salty-ocean-with-more-water-than-earth/