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Researchers pioneer method to purify water using solar energy

Researchers pioneer method to purify water using solar energy

As the global population grows, fresh water supplies are more precious than ever. While scientists and engineers know how to purify water, making those methods sustainable and energy efficient is another question.

One promising approach is solar-driven distillation, or solar steam generation, which can help us get fresh water from wastewater or seawater. Researchers have used this method to successfully distill small batches of purified water, but they are still searching for a way to do this on a large scale.

Researchers at the University of Chicago’s Pritzker School of Molecular Engineering and UChicago-affiliated Argonne National Laboratory were part of a team that developed a pioneering new method of solar steam generation that could help bring this technology into the real world. The materials can be grown on top of wood, fabric or sponges in an easy, one-step process, and show promise for large-scale manufacturing.

“Solar steam generation techniques are still mostly focused on lab use now,” said Zijing Xia, a graduate student at Pritzker Molecular Engineering and lead author of the research. “We want to find an easy way to fabricate solar steam generators at relatively low cost.”

The results of their innovative work were recently published in the journal Advanced Materials Interfaces.

“We want to find an easy way to fabricate solar steam generators at relatively low cost.”

—Graduate student and study lead author Zijing Xia

In the search for solar steam systems, researchers have already tried various materials which convert light to heat, such as carbon materials, plasmonic metals and semiconductors. But many of these options have relatively low efficiency, among other challenges, and so the search continues for a truly transformative method.

A high-performance solar steam generator will ideally combine several characteristics. It should be buoyant on water, be able to absorb a broad spectrum of light, convert light to heat efficiently and be able to transfer that heat to water. Unfortunately, many previously studied methods lack the porous structure needed to facilitate the heat transfer to water.

“Most existing methods cannot be easily engineered to produce steam-generating devices with both arbitrary control over the shape and high photothermal efficiency,” Xia said.

What sets Xia’s method apart is the use of a porphyrin covalent organic framework, or POF. A newly discovered class of materials, POFs can grow uniformly on the surface of a variety of materials with different levels of porosity, and they show high performance for water evaporation. POFs also have unique light-harvesting characteristics beneficial for new applications.

In the lab, POFs successfully grew on the inner and outer surfaces of every tested material. And every template showed favorable photothermal properties, indicating that POF-based materials are promising candidates for solar steam generation. The POF membrane was able to capture more than 95% of light across the majority of the spectrum of sunlight.

The most promising result of the research, Xia said, was the POFs’ ability to grow at the surface of many different kinds of materials, including membranes, fabrics, sponges and wood. The wood showed particularly strong performance, with researchers measuring roughly 80% light-to-steam conversion efficiency.

Solar Steam Illustration

An illustration of water evaporation through the POF‐based materials. (Credit: Zijing Xia et al)

The ability of POFs to grow on many types of materials makes them easily adaptable for use with locally available materials. This versatility, coupled with the easy, one-step fabrication process, could make the method practical for large-scale production.

The POF-based approach proved highly effective in a lab setting, and the research team plans to conduct further experiments outside the lab to observe the practical performance of POFs.

So far, the research suggests POFs could help drive the sustainable water purification systems of the future.

“POF-based interface engineering design shows promise for large-scale purification methods, and it could also be used for desalination, wastewater treatment and beyond,” Xia said.

Other authors of the paper include PME graduate students Ruben Z. Waldman and Chao Zhang, PME professor and Argonne scientist Shrayesh Patel, and Argonne scientist and PME fellow Seth Darling. Additional authors include Zhaowei Chen of Argonne, Hao-Cheng Yang of Sun Yat-sen University and Yusen Zhao of UCLA.

Citation: “Porphyrin Covalent Organic Framework (POF)-Based Interface Engineering for Solar Steam Generation.” Zijing Xia et al. Advanced Materials Interfaces. Doi: 10.1002/admi.201900254

Funding: The Advanced Materials for Energy-Water Systems (AMEWS) Center

Materials provided by the University of Chicago

Sommaroy Island

A Norwegian Island hopes to be the first place in the world to abolish time

When people travel to the Nordic island, Sommarøy they have to forget the concept of time. Some of the travellers do this quite straight hence the bridge connecting the fishing village to the mainland is sprinkled with many discarded watches.

In West Tromsø which is located to the north of the Arctic Circle time is of very little significance. The sun does not rise in winter while for 69 summer days it never sets. This place is one of the extremes so its residents are now proposing a very extreme measure. Resident Kjell Hveding of 56 years, a human resources worker is leading the petition for the place to be the first time-free zone in the world. He told CNN that for many of the residents, getting this approved officially would only mean formalizing a practice that has been done for generations.

In Norwegian, Sommarøy means Summer Island which holds true for a part of the year. This time period is free-for-all as both children and grown-ups can alike can take calls at 2am, garden at midnight and swim at unusual times. Hveding told CBC that the discussions of the government about the new law regarding wintertime or summertime are insignificant here as it does not affect the citizens in any way. People here in the north of Arctic Circle lead a very different kind of life.

Hveding managed to gather close to 100 signatures which is nearly a third of the total population and he gave the list to the local member of parliament. The details of the proposal are not completely clear, as many have criticized the move as a way to boost the tourism of the place, while some feel it is just a symbolic move.

If the normal timekeeping method is abolished then it would mean removing the strict rigidity of a schedule from the lives of people. However even then, people need to go to work, attend schools or meet their friends.

What is to be accepted is that the daily rhythms of a human body follow the sun and not the clocks. Human beings have adapted the 24 hour cycle which is due to Earth’s rotation. Several of the activities performed by the human body follow the 24 hour routine. This internal body clock is followed by every organ in the body, so even though people who spent a lot of time inside caves lost the sense of time, their bodies still followed the same 24 hour cycle.
So we may choose to discard clocks but we cannot discard time.

The newly described stone eating shipworm, known as Lithoredo abatanica.

Researchers discover stone eating creatures in Philippines

Researchers associated with numerous institutions across the U.S. have discovered a rare species of shipworms named Lithoredo abatanica that feeds on rocks and stones instead of woods. They published a paper in the Proceedings of the Royal Society B and described their study and the discovery.

The shipworms are water-dwelling mollusks which are known due to their ability to chew the wood and digest it. They are also popular for creating holes in wooden structures present in water and now, the researchers claim to have discovered a species of these shipworms that do not feed on wood at all but eats the limestone instead.

After breaking through the rocks to get a specimen of these worms, they reported their small size of 150mm and their close resemblance to worms than other mollusks. Unlike the wood-eating shipworms, these worms have large, flat teeth that could scrape away rocks unlike, sharp invisible teeth of the wood eater ship worms which could cover the shells and lacked the sac which was used to digest these woods. In addition to this, these shipworms were also found to excrete sand. Researchers, however, cannot determine any motive behind their rock eating nature but say that it does not impart any nutritional value.

These ship worms which eat rocks have the tendency to change the course of rivers as well. These shipworms have extremely shrunken shells, two in number which is modified into drill like heads.

The regular wood eating marine ship worms store the wood that they eat in a very special digestive sac which they ingest and scrape away to make a protective burrow for itself. The rock-eating ship worms do the same except that they differ from the usual ones in the fact that they lack the sac.

The rock-eating ship worms rely on the bacteria that reside in their gills to produce nutrients and food which is sucked in by this newly existing shipworms from the hind end for nourishment. The gills found in the stone-eating shipworms are quite larger than normal, which shows that they are important for their survival. Researchers are working on how their metabolism works.

Scottish Crannog Centre Loch Tay

Researchers find artificial islands in Scotland to be much older than previous estimates

Ancient human beings in the northern part of British Isles did not live on dry land always. In Scotland, Ireland and Wales, there are several artificial islands which are present even to this day. Named as crannogs, these structures were built by prehistoric humans in the middle of rivers, lakes. It has not been known exactly when these structures were constructed. Normally, archaeologists have estimated it to be built around 800 BCE. However, recent evidence tells a different story. These structures could have been built much before than realised by researchers. The study has been published in Antiquity journal.

With the help of radiocarbon dating on sites located in the Outer Hebrides which is the Western Isles of Scotland, scientists have detected crannogs which date back as far as 3640-3360 BCE, which means that early human beings started building them 5500 years ago, even before the construction of Stonehenge.

Archaeologist Fraser Sturt, University of Southampton told that the crannogs are a symbol of monumental effort made thousands of years before to construct mini-islands by piling up rocks on loch bed. This is not the first time that researchers have thought about the Neolithic origins of the crannogs. Excavations carried out in the 1980s showed that they could date back thousands of years although for decades no such other specimens were located.

Things were shaken up when Chris Murray, former Royal Navy diver who resided in Scottish Isle of Lewis discovered a collection of very well preserved Early/Middle Neolithic pots on the loch bed while diving. Researchers then investigated Loch Arnish and other crannogs, many of which were not present in archaeological records with the help of Google Earth.

In total, the team discovered more than 200 Neolithic vessels made from ceramic, from five crannogs – which is an evidence of an extensive cultural practice we had not known about until now. Survey of these sites has demonstrated that crannogs had been a feature of the Neolithic and they may have been special locations, as found from evidence of deposition of material culture in the water.

According to the researchers, by the quantities of material identified and position of vessels in relation to islets, it is clear that the pots were intentionally deposited in water. Presence of soot on external surfaces and inner charred residues show that they were used before deposition. The amount of work gone into creating these giant structures make it clear that they had unique importance to the early community. The crannogs may have been reserved for important feasts, or mortuary rituals.

Carbon Escape

An escape route for carbon

As many of us may recall from grade school science class, the Earth’s carbon cycle goes something like this: As plants take up carbon dioxide and convert it into organic carbon, they release oxygen back into the air. Complex life forms such as ourselves breathe in this oxygen and respire carbon dioxide. When microbes eat away at decaying plants, they also consume the carbon within, which they convert and release back into the atmosphere as carbon dioxide. And so the cycle continues.

The vast majority of the planet’s carbon loops perpetually through this cycle, driven by photosynthesis and respiration. There is, however, a tiny fraction of organic carbon that is continually escaping through a “leak” in the cycle, the cause of which is largely unknown. Scientists do know that, through this leak, some minute amount of carbon is constantly locked away and preserved in the form of rock for hundreds of millions of years.

Now, researchers from MIT and elsewhere have found evidence for what may be responsible for carbon’s slow and steady escape route.

In a paper published today in the journal Nature, the team reports that organic carbon is leaking out of the carbon cycle mainly due to a mechanism they call “mineral protection.” In this process, carbon, in the form of decomposed bits of plant and phytoplankton material, gloms onto particles of clay and other minerals, for instance at the bottom of a river or ocean, and is preserved in the form of sediments and, ultimately, rock.

Mineral protection may also explain why there is oxygen on Earth in the first place: If something causes carbon to leak out of the carbon cycle, this leaves more oxygen to accumulate in the atmosphere.

“Fundamentally, this tiny leak is one reason why we exist,” says Daniel Rothman, professor of geophysics in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “It’s what allows oxygen to accumulate over geologic time, and it’s why aerobic organisms evolved, and it has everything to do with the history of life on the planet.”

Rothman’s co-authors on the paper include Jordon Hemingway, who led the work as a graduate student at MIT and the Woods Hole Oceanographic Institution and is now a postdoc at Harvard University, along with Katherine Grant, Sarah Rosengard, Timothy Eglinton, Louis Derry, and Valier Galy.

Burning dirt

Scientists have entertained two main possibilities for how carbon has been leaking out of the Earth’s carbon cycle. The first has to do with “selectivity,” the idea that some types of organic matter, due to their molecular makeup, may be harder to break down than others. Based on this idea, the carbon that is not consumed, and therefore leaks out, has been “selected” to do so, based on the initial organic matter’s molecular structure.

The second possibility involves “accessibility,” the notion that some organic matter leaks out of the carbon cycle because it has been made inaccessible for consumption via some secondary process. Some scientists believe that secondary process could be mineral protection — interactions between organic carbon and clay-based minerals that bind the two together in an inaccessible, unconsumable form.

To test which of these mechanisms better explains Earth’s carbon leak, Hemingway analyzed sediment samples collected from around the world, each containing organic matter and minerals from a range of river and coastal environments. If mineral preservation is indeed responsible for locking away and preserving carbon over geologic timescales, Hemingway hypothesized that organic carbon bound with clay minerals should last longer in the environment compared with unbound carbon, resisting degradation by foraging microbes, or even other forces such as extreme heat.

The researchers tested this idea by burning each sediment sample and measuring the amount and type of organic carbon that remained as they heated the sample at progressively higher temperatures. They did so using a device that Hemingway developed as part of his PhD thesis.

“It’s been hypothesized that organic matter that sticks to mineral surfaces will stick around longer in the environment,” Hemingway says. “But there was never a tool to directly quantify that.”

“Beating up a natural process”

In the end, they found the organic matter that lasted the longest, and withstood the highest temperatures, was bound to clay minerals. Importantly, in a finding that went against the idea of selectivity, it didn’t matter what the molecular structure of that organic matter was — as long as it was bound to clay, it was preserved.

The results point to accessibility, and mineral preservation in particular, as the main mechanism for Earth’s carbon leak. In other words, all around the world, clay minerals are slowly and steadily drawing down tiny amounts of carbon, and storing it away for thousands of years.

“It’s this clay-bound protection that seems to be the mechanism, and it seems to be a globally coherent phenomenon,” Hemingways says. “It’s a slow leak happening all the time, everywhere. And when you integrate that over geologic timescales, it becomes a really important sink of carbon.”

The researchers believe mineral protection has made it possible for vast reservoirs of carbon to be buried and stored in the Earth, some of which has been pressed and heated into petroleum over millions of years. At the Earth’s geologic pace, this carbon preserved in rocks eventually resurfaces through mountain uplift and gradually erodes, releasing carbon dioxide back into the atmosphere ever so slowly.

“What we do today with fossil fuel burning is speeding up this natural process,” Rothman says. “We’re getting it out of the ground and burning it right away, and we’re changing the rate at which the carbon that was leaked out is being returned to the system, by a couple orders of magnitude.”

Could mineral preservation somehow be harnessed to sequester even more carbon, in an effort to mitigate fossil-fuel-induced climate change?

“If we magically had the ability to take a fraction of organic matter in rivers or oceans and attach it to a mineral to hold onto it for 1,000 years, it could have some advantages,” Rothman says. “That’s not the focus of this study. But the longer soils can lock up organic matter, the slower their return to the atmosphere. You can imagine if you could slow that return process down just a little bit, it could make a big difference over 10 to 100 years.”

Materials provided by Massachusetts Institute of Technology

Yakutia aerial

Fully preserved head of wolf from Ice Age found in Siberia

A perfectly preserved furry head from the Ice Age era has been found by Russian scientists in an expedition of the Mammoth Fauna Study Department at the Russian Academy of Sciences. The head was found preserved in the Siberian Permafrost.  The head of this wolf was predicted to be close to 40,000 years old and was discovered in the Russian arctic region of Yakutia. The wolf’s head was first found by Pavel Efimov, a local resident near the Tirekhtyakh River.

A top researcher from the local branch of Russian Academy of Sciences named Valery Plotnikov has said that the animal belonged to an ancient subspecies of a wolf that had lived the same time when the mammoths lived and slowly led to the extinction of the mammoth species.

Ice Age is a lengthy period in the reduction of temperature of Earth resulting in the expansion of polar ice sheets. Presently Earth is in Quaternary glaciation.

The head which was found is said to be of an adult wolf which is about 25% bigger than the ideal size of the wolves found today. Jikei University in Japan conducted tomographic study and took the help of carbon dating to determine the age of wolf. The gender of the animal was not mentioned as to whether it was male or whether it was female. The size of the wolf’s head is nearly 40 centimetres and it is estimated that the wolf was 2 to 4 years old when it died.

Albert Protopopov, a leading researcher at the Russian Academy of Sciences remarked that this is a unique discovery as this is the first time the remains of a fully grown Pleistocene wolf has been found. He further added that now it will be compared to the wolves of the present day and determine in a clearer way how wolves evolved along with the reconstruction of its appearance.

The skulls of the wolves which were previously found were without any covering of tissues and fur whereas the one found currently has a layer of tissues and fir along with ears, tongue and a perfectly preserved brain. It was discovered in August 2018 and the study and scientific investigations are still underway for this animal. Its DNA will now be examined by the Swedish Museum of Natural History. According to scientists, the wolf head was found in the same area where a preserved body of a lion cub was found in 2017, who lived in Ice Age.

Purple sea urchin

New research shows why Noah’s ark would not work

A first of a kind study has illuminated that marine species will survive even though in a world where the temperatures are rising and acidity is increasing in the water.

Melissa Pespeni a biologist at the University of Vermont who led the new research has said that moderately sized remnants may have little chance to persist on a climate-changed planet. She led a research which studied the larvae for experiments where the water was made acidic and alkaline. The study has been published in the Proceedings of the Royal Society B journal.

Small minorities of urchins were studied and surprisingly they found out a rare variation in DNA which was essential for their survival. When the water was made acidic the variants increased the frequency in water and let the next generation to choose how the proteins function like the shells which are hard but can be easily dissolved to manage the acidity in the cells. Along with these other needed genetic variation helped them survive in acidic conditions or a range of acid levels. The bigger the population, greater is the variation in the species. If we have a smaller population there are lesser chances of having a genetic variation.

Some organisms have the potential to survive the change due to change in physiology and due to the ability of migration but for many others, their only hope lies in evolution and potential changes in their DNA. The purple sea urchins which stretch from the reefs from California to Alaska are a snack for the otters. Due to the huge number of urchins and the wide expanse of the geographical area, urchins are likely survivors of the harsh future of rising temperatures and acidified oceans. The UVM team has written that the genetic mechanisms that allow rapid adaptation to extreme climatic conditions have been rarely explored.

A single generation experiment was started with 25 urchins caught from the wild. Each female of those 25 produced close to 200,000 eggs each out of which 20,000 survived, the DNA samples of this pool was taken for study and research. This large gene pool gave scientists the idea that the urchins could survive in acidic conditions. They can survive these slight changes in pH and can continue to protect them as long as they keep their population large. Discoveries of facts like these have long term implications on their survival and continuity of their species.

Pitcher Plant

Scientists discover meat eating plants in Canada

Biologists at the University of Guelph have recently discovered a meat-eating pitcher plant in the Ontario’s Algonquin Park. A typical pitcher plant feeds only on bugs and flies however this pitcher plant feeds even on salamanders.

According to a study published in the journal Ecology, the researcher calls this an unexpected and fascinating case of plants eating vertebrates in our backyard. Pitcher plants across Canada have been known to eat only the insects and spiders that fall into their bell-shaped structure but there were no reports about salamander being caught in a pitcher plant even from the oldest parks in Canada.

In summer 2017, an undergraduate student named Teskey Baldwin found a salamander trapped inside a pitcher plant during a U of G field of an ecology course. He has been monitoring pitcher plants around a single pond in the park in fall 2018. The team found that one in five pitcher plants contained juvenile amphibians which were small like a human finger. Some plants had more than one salamander captured in them. These observations were coincident with the pulses of young salamanders that crawl into the land from their larval state.

A researcher named Alex Smith has said that bog ponds usually lack fish and is the reason why salamanders are a key predator and prey species in food webs. He believes that the animals may have fallen into the plant to escape predators or maybe attracted by the insects in the pitcher plant or may have fallen directly.

Salamanders once trapped can survive for 3 days or up to 19 days. The digestive enzymes of the plants and specialized leaves break down the animal captured. Heat, starvation and infection by pathogens inside the pitcher plant may be another reason as to why they die inside the pitcher plant. The plant also gains precious nitrogen and nutrients if they turn to carnivores.

Some types of plants called Venus Fly Trap and Seymour plant in the musical Little Shop of Horrors are similar to the pitcher plant and use sticky leaves to catch insects. Pitcher plants have been known to us since the 18th century. A species found a decade ago in Asia is known to consume even small birds and mice along with insects. However, this discovery has raised a lot of questions like the importance of salamander as a prey and that the salamanders have to compete with plants for insects prey and may even choke the plant. The park officials are taking prompt actions and writing interpretive material for further study.


Convergent Lady Beetle

Massive ladybug swarm appears on the weather radar

A normal Tuesday night for meteorologists at California turned into a strange surprise when they spotted a huge blob on their National Weather Service Radar which appeared to be 130 by 130 kilometres and was noticed to be moving southwards over the San Bernardino County.

The blob was a strange phenomenon owing to the relatively normal weather conditions on that day with no expectations of rain or thunderstorms as claimed by meteorologist Casey Oswant of the National Weather Service in San Diego but that was not the case as per the radar data. A local weather spotter was requested to eyeball the mass; there was no rain actually on the location even though the radar showed raindrop sized objects. The weather spotters had identified ladybugs and the conclusion was drawn that the giant weird blob was due to a tremendous swarm of red beetles on the move. California is home to 200 species which is the reason as to why these ladybugs could not be identified but it is said to be a Hippodamia Convergens which is a convergent ladybug.

They were spotted flying at an altitude close to 1.5 to 2.7 kilometres. The main mass of the supposed swarm was not as spread out as seen on the radar. It was consolidated in an area of 16 kilometres across and it was noticed that the ladybugs were spread out and not consolidated in one place. Ladybugs migrate to milder climates with warm weather in order to survive the snowy weather and return back in spring to feast on a glut of aphids.

An entomologist at the Cornell University named John Losey has stated a worry in this observation as to why we are seeing this big swarm now and why this was not observed initially. He believes it might have to do something with climate change. The best possibility would be that California might be a suitable place for the environment of ladybugs. The team is working hard to confirm this idea but have not turned up with suitable evidence.

An entomologist Steve Heydon of the Bohart Museum of Entomology claimed that the temperatures were cooler than the ladybugs generally prefer. The ladybug theory is a bit hard to believe as these insects generally do not travel in swarms of close to millions of bees which are necessary to produce a radar echo is what ecologist James Cornett has to say on this issue. There is a possibility that we may never possibly know what caused the mystery signal.


We consume a minimum of 74,000 microplastic particles in a single year

Microplastics have reached every corner of the ecosystem on the planet. The deepest ocean trenches to the highest mountain peaks, it is due to humans that microplastics have spread across the ecosystem. An average person today is set to consume close to 74,000 pieces of microplastic every year. It is said to be undervalued as the intake of microplastics can be through sugars, fish, alcohol, bottled water and even the air we breathe. The microplastic database is compared to US Dietary data which predicts a person consumes anything between 74,000 to 121,000 pieces of microplastic particles.

This analysis and report is an alarming indication that the harm we cause to the ecosystem as analyzed by Thavamani Palanisami, a researcher in contamination risk assessment at the University of Newcastle not directly involved in the research. This is a crisis which not only affects the ecosystem but in turn, affects the food we eat and water we drink. This number is highly an average and can undergo a lot of variation. The number has been derived from an American’s daily food consumption and only 14% of calorific intake. The amount of plastic in the remaining 85% is not possible to determine and considering that too, the average microplastic consumption may be close to several hundred thousand yearly.

The research, however, does not mention the costs to be counted on the human health factor. The ill effects of microplastic are highly unknown. Recent research made headlines when researchers found evidence of microplastic in human excreta samples from all over the world. The study has been published in Environmental Science and Technology.

Scientists have proposed few potentially hazardous pathways for harm to the human body but the larger ill effects are not known. Once the microplastics enter the gut they release toxic substances causing stress and cancer, according to the researchers. Similar things could happen when microplastic substances enter through the lungs. Anas Ghadouani, an environmental engineer at the University of Western Australia raises a very serious and a key question about the impacts of microplastics on the human body.

According to a study, bottled water contains 90% more microplastics per litre than tap water. Drinking bottled water for a day may lead to microplastic intake of 349 particles compared to just 16 particles from tap water. Avoiding bottled water is just one way in which we can reduce the intake of microplastics. If the precautionary measures are not followed then the most effective way to reduce microplastic consumption is to reduce the plastic products in our daily life.