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How does reverse osmosis work?



Unlike osmosis, we cannot simply observe reverse osmosis in many everyday circumstances. It was only in the 1950s when researchers began to study how desalinate ocean water that reverse osmosis was considered as a possibility. They found that applying pressure to the salt water side could work to produce more fresh water, but the amount they created was extremely small and useless on any practical scale. What changed?

A much more advanced filter, created by two scientists at the University of California, Los Angeles. Hand molded membranes cellular acetate (the polymer used in photographic film) allowed more water to pass through much faster, and in 1965 the first plan for reverse osmosis desalination was launched in Coaling, California. [source: The Economist].

This brings us to one of the most common applications of reverse osmosis, which we have already discussed: water desalination. Including large factories (more than 177 countries). with the help of desalination) or smaller operations like a filter you can take on a hike to ensure healthy drinking water. [source: FDU].

Reverse osmosis is also one of the few ways to remove certain minerals or chemicals from water. Some water sources have extremely high levels of natural fluoridation, which can lead to enamel fluorosis (mottled teeth) or much more severe skeletal fluorosis (actual bending of human bones or skeleton). Reverse osmosis can filter out fluorine or other impurities on a large scale, which a charcoal-based filter (such as the one most commonly found in homes) cannot.

It is also used for recycling; chemicals used to treat metals for recycling create harmful wastewater, and reverse osmosis can pull clean water for better chemical disposal. But even more fun than recycling? Wastewater treatment is reverse osmosis, in which wastewater is put through a process to create something drinkable. They don’t call it the “faucet toilet” for nothing, and while it may make you think, it’s a promising way for developing countries to produce drinking water.

But reverse osmosis is used in other industries as well; maple syrupis essentially made using osmosis to separate the sugary concentrate from the water in the juice. V dairy industry uses reverse osmosis filtration to concentrate whey and milk, and the wine industry uses it filter out unwanted items such as certain acids, smoke, or to control alcohol content. Reverse osmosis is used to create pure ethanol free of impurities.

Another fun thing about reverse osmosis is that the high pressure that makes reverse osmosis efficient can actually recycle itself. High pressure pumps pump the water and the remaining salt water is ejected at an extremely high rate. If this branch passes through a turbine or motor, the pressure can be reused for the pumps that originally pump water, thus re-collecting energy.

All this industrial jazz is great, but how does reverse osmosis technology affect you, the consumer, on a smaller scale?

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Stunning mosaic of young star clusters created from 1 million telescope images



CAPE CANAVERAL, Florida. (AP) — Astronomers have created a stunning mosaic of small star clusters lurking in our galaxy’s backyard.

A montage posted Thursday shows five vast nurseries of stars less than 1,500 light-years away.

A light year is almost 6 trillion miles (9.7 trillion kilometers).

To compile their atlas, the scientists pieced together more than 1 million images taken over five years by the European Southern Observatory in Chile.

The observatory’s infrared survey telescope was able to peer through clouds of dust and discern young stars.

“We can detect even the thinnest light sources, such as stars much less massive than the sun, revealing objects that no one has ever seen before,” said study lead author Stefan Meingast of the University of Vienna.

According to Meingast, the observations made from 2017 to 2022 will help researchers better understand how stars evolve from dust.

The findings, published in the journal Astronomy & Astrophysics, add to observations by the European Space Agency’s Gaia spacecraft, about 1.5 million kilometers away.

According to the researchers, Gaia focuses on optical light, letting through most of the objects obscured by cosmic dust.

The Associated Press Department of Health and Science receives support from the Howard Hughes Medical Institute Science and Education Media Group. AP is solely responsible for all content.

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Astronomers have recorded the largest cosmic explosion ever seen



Last year, astronomers recorded the brightest explosion on record, a gamma-ray burst known as GRB 221009A, that lasted just over ten hours. Although it was brighter than AT2021lwx, it only lasted a fraction of the time, meaning that the explosive yield of AT2021lwx was much higher.

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Giant clams bleach in warm water



This article was originally posted on Hakai magazine, online publication about science and society in coastal ecosystems. Read more stories like this at

Bleaching occurs when a stressed sea creature, most commonly a coral, expels its symbiotic algae and turns ghostly white, often in response to a warming sea. But bleaching doesn’t just affect corals. Giant clams – massive clams that can reach over 1.2 meters in diameter and weigh up to 225 kilograms – can also become discolored. And in a recent study, scientists have learned more about how bleaching destroys these sessile giants, affecting everything from their nutrition to their reproduction.

Giant clams live on coral reefs and are the largest bivalves on Earth. Like corals, giant clams bleach when they are stressed, often in response to excessively warm water. As with coral, a bleached giant clam expels algae called zooxanthellae that live inside it. These algae live in the soft tissues of the clam’s mantle and provide the animal with energy through photosynthesis, leaving the discolored clam with less energy and nutrients. In the worst case, bleaching can kill giant clams due to a lack of food.

Scientists have been studying the bleaching of giant clams for decades. In 1997 and 1998, during a short period of widespread coral bleaching worldwide, corals died at least 32 disparate countries, bleached giant clams have been observed from the Great Barrier Reef in Australia to French Polynesia following a significant rise in water temperatures in the South Pacific. In 2010, similar water temperatures off Koh Man Nai in Thailand also killed dozens of people.

Of the 12 species of giant clams, some are more resistant to heat stress than others. But even if the giant mollusk survives the bleaching, other physiological functions can be severely affected, the scientists found.

Recent Research in the Philippines, wild mollusks, for example, have found that bleaching can prevent them from reproducing. Bleaching reduces the number of eggs that giant clams produce, and the stronger the bleach, the fewer eggs they lay. Playback “requires a lot of energy. So instead of using that energy to reproduce, they just use it for their own survival,” says Sherry Lin Saiko, lead author of the study and a PhD student at Ryukyu University in Japan.

Mei Ling Neo, a marine ecologist and giant clams expert at the National University of Singapore who was not involved in the study, says the work contributes to the story of how climate change may have “impacts on the lifespan of species.”

Overall, she says, we know much more about how climate change is affecting corals than we do about marine species with similar physiologies. “By understanding how other symbiotic species are responding to climate change, each species becomes a unique indicator of how the entire reef ecosystem works.”

It turns out that bleached giant clams are often better at dealing with bleaching than corals. Near Koh Man Nai, 40 percent of the discolored clams changed color after a few months as zooxanthellae repopulated their tissues when temperatures dropped again. Since the 1997-1998 bleaching, more than 95 percent of the 6,300 bleached clams off Australia’s Orpheus Island have recovered.

Giant clams also seem to lend themselves to replenishment. In the Philippines, where the largest species live, Tridacna gigasbecame extinct locally in the 1980s, replenishment brought it back.

“Shellfish are not just an organism,” says Saiko. “It’s not that we just keep them there to be there,” she adds, “they have a lot of benefits and ecosystem services like [boosting] fishing [and] tourism”.

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