Scientists build bacteria-powered battery on single sheet of paper

Researchers have created a bacteria-powered battery on a single sheet of paper that can power disposable electronics. The manufacturing technique reduces fabrication time and cost, and the design could revolutionize the use of bio-batteries as a power source in remote, dangerous and resource-limited areas.

Instead of ordering batteries by the pack, we might get them by the ream in the future. Researchers at Binghamton University, State University of New York have created a bacteria-powered battery on a single sheet of paper that can power disposable electronics. The manufacturing technique reduces fabrication time and cost, and the design could revolutionize the use of bio-batteries as a power source in remote, dangerous and resource-limited areas.

"Papertronics have recently emerged as a simple and low-cost way to power disposable point-of-care diagnostic sensors," said Assistant Professor Seokheun "Sean" Choi, who is in the Electrical and Computer Engineering Department within the Thomas J. Watson School of Engineering and Applied Science. He is also the director of the Bioelectronics and Microsystems Lab at Binghamton.

"Stand-alone and self-sustained, paper-based, point-of-care devices are essential to providing effective and life-saving treatments in resource-limited settings," said Choi.

On one half of a piece of chromatography paper, Choi and PhD candidate Yang Gao, who is a co-author of the paper, placed a ribbon of silver nitrate underneath a thin layer of wax to create a cathode. The pair then made a reservoir out of a conductive polymer on the other half of the paper, which acted as the anode. Once properly folded and a few drops of bacteria-filled liquid are added, the microbes' cellular respiration powers the battery.

"The device requires layers to include components, such as the anode, cathode and PEM (proton exchange membrane)," said Choi. "[The final battery] demands manual assembly, and there are potential issues such as misalignment of paper layers and vertical discontinuity between layers, which ultimately decrease power generation."

Different folding and stacking methods can significantly improve power and current outputs. Scientists were able to generate 31.51 microwatts at 125.53 microamps with six batteries in three parallel series and 44.85 microwatts at 105.89 microamps in a 6x6 configuration.

It would take millions of paper batteries to power a common 40-watt light bulb, but on the battlefield or in a disaster situation, usability and portability is paramount. Plus, there is enough power to run biosensors that monitor glucose levels in diabetes patients, detect pathogens in a body or perform other life-saving functions.

"Among many flexible and integrative paper-based batteries with a large upside, paper-based microbial fuel cell technology is arguably the most underdeveloped," said Choi. "We are excited about this because microorganisms can harvest electrical power from any type of biodegradable source, like wastewater, that is readily available. I believe this type of paper biobattery can be a future power source for papertronics."

The innovation is the latest step in paper battery development by Choi. His team developed its first paper prototype in 2015, which was a foldable battery that looked much like a matchbook. Earlier this year they unveiled a design that was inspired by a ninja throwing star.

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Impact of climate change on microbial biodiversity

The scientists discovered that climate change affects biodiversity most strongly in the most natural environments, as well as the most nutrient enriched environments. This means that these extremes are most susceptible to future changes in temperatures.

The results are just published in the journal Nature Communications.

We still know fairly little about the specific impacts of climate change and human activity, such as nutrient enrichment of waterways, on broad geographical scales. Researchers from the Department of Geosciences and Geography at the University of Helsinki, the Finnish Environment Institute, and the Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences have studied hundreds of microcosms in mountainous regions with the aid of natural temperature gradients in the studied areas, while modifying the enrichment level in field tests.

The results indicate that the bacteria in elevated tropical areas are similar to e.g. those in arctic areas. As a result of changes in temperature and aquatic enrichment, significant alterations occur in the microcosms, and as the enrichment increases, biodiversity reduces, says Associate Professor Janne Soininen.

Species adapted to austere conditions in danger

Experiments in mountainous regions indicated that differentiating between the effects of temperature variations and aquatic nutrient enrichment can help us understand the possible effects of climate change in different environments. The typically austere, i.e. nutrient-poor, waters in the north, for example, are extremely susceptible to temperature variations, and as the climate warms up, species that have adapted to the cold will decline. The only good news is that biodiversity may improve at first, as the climate warms up, as species that thrive in warmer areas increase, until biodiversity again starts to decline when the temperature continues to rise.

Another significant finding in this research was that, like plants and animals, different species of bacteria clearly live at different levels of elevation, and the bacteria in high mountain areas in the tropics are similar to the bacteria in arctic areas, due to the similar cold climate.

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Music in the brain: The first imaging genetic study linking dopaminergic genes to music

Sounds, such as music and noise, are capable of reliably affecting individuals' moods and emotions, possibly by regulating brain dopamine, a neurotransmitter strongly involved in emotional behavior and mood regulation.

However, the relationship of sound environments with mood and emotions is highly variable across individuals. A putative source of variability is genetic background.

In this regard, a new imaging genetics study directed by Professor Elvira Brattico from Aarhus University and conducted in two Italian hospitals in collaboration with the University of Helsinki (Finland) has provided the first evidence that the effects of music and noise on affective behavior and brain physiology are associated with genetically determined dopamine functionality.

In particular, this study, published in the journal Neuroscience, revealed that a functional variation in dopamine D2 receptor gene (DRD2 rs1076560) modulates the impact of music as opposed to noise on mood states and emotion-related prefrontal and striatal brain activity, evidencing a differential susceptibility for the affect-modulatory effects of music and noise on the GG and GT genotypes.

In more details, results showed mood improvement after music exposure in GG subjects and mood deterioration after noise exposure in GT subjects. Moreover, the music as opposed to noise environment decreased the striatal activity of GT subjects as well as the prefrontal activity of GG subjects while processing emotional faces.

These results are novel in identifying a biological source of variability in the impact of sound environments on emotional responses. The first author of the study, Tiziana Quarto, Ph.D. student at University of Helsinki under supervision of Prof. Brattico, further comments:

"Our approach allowed the observation of the link between genes and phenotypes via a true biological path that goes from functional genetic variations (for which the effects on molecular function is known) to brain physiology subtending behavior. The use of this approach is especially important when the investigated behavior is complex and very variable across subjects, because this means that many biological factors are involved."

"This study represents the first use of the imaging genetics approach in the field of music and sounds in general. We are really excited about our results because they suggest that even a non-pharmacological intervention such as music, might regulate mood and emotional responses at both the behavioral and neuronal level," says Professor Elvira Brattico.

"More importantly, these findings encourage the search for personalized music-based interventions for the treatment of brain disorders associated with aberrant dopaminergic neurotransmission as well as abnormal mood and emotion-related brain activity."

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A fertilizer dearth foiled animal evolution for eons?

For three billion years or more, the evolution of the first animal life on Earth was ready to happen, practically waiting in the wings. But the breathable oxygen it required wasn't there, and a lack of simple nutrients may have been to blame.

Then came a fierce planetary metamorphosis. Roughly 800 million years ago, in the late Proterozoic Eon, phosphorus, a chemical element essential to all life, began to accumulate in shallow ocean zones near coastlines widely considered to be the birthplace of animals and other complex organisms, according to a new study by geoscientists from the Georgia Institute of Technology and Yale University.

Along with phosphorus accumulation came a global chemical chain reaction, which included other nutrients, that powered organisms to pump oxygen into the atmosphere and oceans. Shortly after that transition, waves of climate extremes swept the globe, freezing it over twice for tens of millions of years each time, a highly regarded theory holds. The elevated availability of nutrients and bolstered oxygen also likely fueled evolution's greatest lunge forward.

After billions of years, during which life consisted almost entirely of single-celled organisms, animals evolved. At first, they were extremely simple, resembling today's sponges or jellyfish, but Earth was on its way from being, for eons, a planet less than hospitable to complex life to becoming one bursting with it.

Earth's true genesis

In the last few hundred million years, biodiversity has blossomed, leading to dense jungles and grasslands echoing with animal calls, and waters writhing with every shape of fin and color of scale. And most every stage of development has left its mark on the fossil record.

The researchers are careful not to imply that phosphorus necessarily caused the chain reaction, but in sedimentary rock taken from coastal areas, the nutrient has marked the spot where that burst of life and climate change took off. "The timing is definitely conspicuous," said Chris Reinhard, an assistant professor in Georgia Tech's School of Earth and Atmospheric Sciences.

Reinhard and Noah Planavsky, a geochemist from Yale University, who headed up the research together, have mined records of sedimentary rock that formed in ancient coastal zones, going down layer by layer to 3.5 billion years ago, to compute how the cycle of the essential fertilizer phosphorus evolved and how it appeared to play a big part in a veritable genesis.

They noticed a remarkable congruency as they moved upward through the layers of shale into the time period where animal life began, in the late Proterozoic Eon.

"The most basic change was from very limited phosphorus availability to much higher phosphorus availability in surface waters of the ocean," Reinhard said. "And the transition seemed to occur right around the time that there were very large changes in ocean-atmosphere oxygen levels and just before the emergence of animals."

Phosphorus at the beach

Reinhard and Planavsky, together with an international team, have proposed that a scavenging of nutrients in an anoxic (nearly O2-free) world stunted photosynthetic organisms that otherwise had been poised for at least two billion years to make stockpiles of oxygen. Then that balanced system was upset and oceanic phosphorus made its way to coastal waters.

The scientists published their findings in the journal Nature. Their research was funded by the National Science Foundation, the NASA Astrobiology Institute, the Sloan Foundation and the Japan Society for the Promotion of Science.

The work provides a new view into what factors allowed life to reshape Earth's atmosphere. It helps lay a foundation that scientists can apply to make predictions about what would allow life to alter exoplanets' atmospheres, and may inspire deeper studies, here on Earth, of how oceanic-atmospheric chemistry drives climate instability and influences the rise and fall of life through the ages.

Cyanobacteria, the mother of O2

Complex living things, including animals, usually have an immense metabolism and require ample O2 to drive it. The evolution of animals is unthinkable without it.

The path to understanding how a nutrient dearth would starve out breathable oxygen production leads back to a very special kind of bacteria called cyanobacteria, the mother of oxygen on Earth.

"The only reason we have a well-oxygenated planet we can live on is because of oxygenic photosynthesis," Planavsky said. "O2 is the waste product of photosynthesizing cells, like cyanobacteria, combining CO2 and water to build sugars."

And photosynthesis is an evolutionary singularity, meaning it only evolved once in Earth's history -- in cyanobacteria.

Some other biological phenomena evolved repeatedly in dozens or hundreds of unrelated incidents across the ages, such as the transition from single-celled organisms to rudimentary multicellular organisms. But scientists are confident that oxygenic photosynthesis evolved only this one time in Earth's history, only in cyanobacteria, and all plants and other beings on Earth that photosynthesize coopted the development.

The iron anchor

Cyanobacteria are credited with filling Earth's atmosphere with O2, and they've been around for 2.5 billion years or more.

That begs the question: What took so long? Basic nutrients that fed the bacteria weren't readily available, the scientist hypothesize. The phosphorus, which Planavsky and Reinhard specifically tracked, was in the ocean for billions of years, too, but it was tied up in the wrong places.

For eons, the mineral iron, which once saturated oceans, likely bonded with phosphorus, and sank it down to dark ocean depths, far away from those shallows -- also called continental margins -- where cyanobacteria would have needed it to thrive and make oxygen. Even today, iron is used to treat waters polluted with fertilizer to remove phosphorus by sinking it as deep sediment.

The researchers also used a geochemical model to show how a global system with high iron concentration and low phosphorus availability combined with low nitrogen availability in ocean shallows could perpetuate itself in a low-oxygen world.

"It looks to have been such a stable planetary system," Reinhard said. "But it's obviously not the planet we live on now, so the question is, how did we transition from this low-oxygen state to where we are now?"

What ultimately caused that change is a question for future research.

Phosphorus starting pistol

But something did change about 800 million years ago, and cyanobacteria and other minute organisms in continental margin ecosystems got more phosphorus, the backbone of DNA and RNA, and a main actor in cell metabolism. The bacteria became more active, reproduced more quickly, ate lots more phosphorus and made loads more O2.

"Phosphorus is not only essential for life," Planavsky said. "What's implicit in all this is: It can control the amount of life on our planet."

When the newly multiplied bacteria died, they fell to the floor of those ocean shallows, stacking up layer by layer to decay and enrich the mud with phosphorus. The mud eventually compressed to stone.

"As the biomass increased in phosphorus content, the more of it landed in layers of sedimentary rock," Reinhard said. "To scientists, that shale is the pages of the sea floor's history book."

Scientists have thumbed through them for decades, compiling data. Planavsky and Reinhard analyzed some 15,000 rock records for their study.

"The first compilation we had of this was only 600 samples," Planavsky said. Reinhard added, "But you could already see it then. The phosphorus jolt was as clear as day. And as the database grew in size, the phenomenon became more entrenched."

That first signal of phosphorus in Earth's coast shallows pops up in the shale record like a shot from a starting pistol in the race for abundant life.

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Research team sets new mark for 'deep learning'

Neuroscience and artificial intelligence experts from Rice University and Baylor College of Medicine have taken inspiration from the human brain in creating a new "deep learning" method that enables computers to learn about the visual world largely on their own, much as human babies do.

In tests, the group's "deep rendering mixture model" largely taught itself how to distinguish handwritten digits using a standard dataset of 10,000 digits written by federal employees and high school students. In results presented this month at the Neural Information Processing Systems (NIPS) conference in Barcelona, Spain, the researchers described how they trained their algorithm by giving it just 10 correct examples of each handwritten digit between zero and nine and then presenting it with several thousand more examples that it used to further teach itself. In tests, the algorithm was more accurate at correctly distinguishing handwritten digits than almost all previous algorithms that were trained with thousands of correct examples of each digit.

"In deep-learning parlance, our system uses a method known as semisupervised learning," said lead researcher Ankit Patel, an assistant professor with joint appointments in neuroscience at Baylor and electrical and computer engineering at Rice. "The most successful efforts in this area have used a different technique called supervised learning, where the machine is trained with thousands of examples: This is a one. This is a two.

"Humans don't learn that way," Patel said. "When babies learn to see during their first year, they get very little input about what things are. Parents may label a few things: 'Bottle. Chair. Momma.' But the baby can't even understand spoken words at that point. It's learning mostly unsupervised via some interaction with the world."

Patel said he and graduate student Tan Nguyen, a co-author on the new study, set out to design a semisupervised learning system for visual data that didn't require much "hand-holding" in the form of training examples. For instance, neural networks that use supervised learning would typically be given hundreds or even thousands of training examples of handwritten digits before they would be tested on the database of 10,000 handwritten digits in the Mixed National Institute of Standards and Technology (MNIST) database.

The semisupervised Rice-Baylor algorithm is a "convolutional neural network," a piece of software made up of layers of artificial neurons whose design was inspired by biological neurons. These artificial neurons, or processing units, are organized in layers, and the first layer scans an image and does simple tasks like searching for edges and color changes. The second layer examines the output from the first layer and searches for more complex patterns. Mathematically, this nested method of looking for patterns within patterns within patterns is referred to as a nonlinear process.

"It's essentially a very simple visual cortex," Patel said of the convolutional neural net. "You give it an image, and each layer processes the image a little bit more and understands it in a deeper way, and by the last layer, you've got a really deep and abstract understanding of the image. Every self-driving car right now has convolutional neural nets in it because they are currently the best for vision."

Like human brains, neural networks start out as blank slates and become fully formed as they interact with the world. For example, each processing unit in a convolutional net starts the same and becomes specialized over time as they are exposed to visual stimuli.

"Edges are very important," Nguyen said. "Many of the lower layer neurons tend to become edge detectors. They're looking for patterns that are both very common and very important for visual interpretation, and each one trains itself to look for a specific pattern, like a 45-degree edge or a 30-degree red-to-blue transition.

"When they detect their particular pattern, they become excited and pass that on to the next layer up, which looks for patterns in their patterns, and so on," he said. "The number of times you do a nonlinear transformation is essentially the depth of the network, and depth governs power. The deeper a network is, the more stuff it's able to disentangle. At the deeper layers, units are looking for very abstract things like eyeballs or vertical grating patterns or a school bus."

Nguyen began working with Patel in January as the latter began his tenure-track academic career at Rice and Baylor. Patel had already spent more than a decade studying and applying machine learning in jobs ranging from high-volume commodities training to strategic missile defense, and he'd just wrapped up a four-year postdoctoral stint in the lab of Rice's Richard Baraniuk, another co-author on the new study. In late 2015, Baraniuk, Patel and Nguyen published the first theoretical framework that could both derive the exact structure of convolutional neural networks and provide principled solutions to alleviate some of their limitations.

Baraniuk said a solid theoretical understanding is vital for designing convolutional nets that go beyond today's state-of-the-art.

"Understanding video images is a great example," Baraniuk said. "If I am looking at a video, frame by frame by frame, and I want to understand all the objects and how they're moving and so on, that is a huge challenge. Imagine how long it would take to label every object in every frame of a video. No one has time for that. And in order for a machine to understand what it's seeing in a video, it has to understand what objects are, the concept of three-dimensional space and a whole bunch of other really complicated stuff. We humans learn those things on our own and take them for granted, but they are totally missing in today's artificial neural networks."

Patel said the theory of artificial neural networks, which was refined in the NIPS paper, could ultimately help neuroscientists better understand the workings of the human brain.

"There seem to be some similarities about how the visual cortex represents the world and how convolutional nets represent the world, but they also differ greatly," Patel said. "What the brain is doing may be related, but it's still very different. And the key thing we know about the brain is that it mostly learns unsupervised.

"What I and my neuroscientist colleagues are trying to figure out is, What is the semisupervised learning algorithm that's being implemented by the neural circuits in the visual cortex? and How is that related to our theory of deep learning?" he said. "Can we use our theory to help elucidate what the brain is doing? Because the way the brain is doing it is far superior to any neural network that we've designed.

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Underwater volcano's eruption captured in exquisite detail by seafloor observatory

Seismic data from the 2015 eruption of Axial Volcano, an underwater volcano about 300 miles off the Oregon coast, has provided the clearest look at the inner workings of a volcano where two ocean plates are moving apart.

The cracking, bulging and shaking from the eruption of a mile-high volcano where two tectonic plates separate has been captured in more detail than ever before. A University of Washington study published this week shows how the volcano behaved during its spring 2015 eruption, revealing new clues about the behavior of volcanoes where two ocean plates are moving apart.

"The new network allowed us to see in incredible detail where the faults are, and which were active during the eruption," said lead author William Wilcock, a UW professor of oceanography. The new paper in Science is one of three studies published together that provide the first formal analyses of the seismic vibrations, seafloor movements and rock created during an April 2015 eruption off the Oregon coast. "We have a new understanding of the behavior of caldera dynamics that can be applied to other volcanoes all over the world."

The studies are based on data collected by the Cabled Array, a National Science Foundation-funded project that brings electrical power and internet to the seafloor. The observatory, completed just months before the eruption, provides new tools to understand one of the test sites for understanding Earth's volcanism.

"Axial volcano has had at least three eruptions, that we know of, over the past 20 years," said Rick Murray, director of the NSF's Division of Ocean Sciences, which also funded the research. "Instruments used by Ocean Observatories Initiative scientists are giving us new opportunities to understand the inner workings of this volcano, and of the mechanisms that trigger volcanic eruptions in many environments.

"The information will help us predict the behavior of active volcanoes around the globe," Murray said.

It's a little-known fact that most of Earth's volcanism takes place underwater. Axial Volcano rises 0.7 miles off the seafloor some 300 miles off the Pacific Northwest coast, and its peak lies about 0.85 miles below the ocean's surface. Just as on land, we learn about ocean volcanoes by studying vibrations to see what is happening deep inside as plates separate and magma rushes up to form new crust.

The submarine location has some advantages. Typical ocean crust is just 4 miles (6 km) thick, roughly five times thinner than the crust that lies below land-based volcanoes. The magma chamber is not buried as deeply, and the hard rock of ocean crust generates crisper seismic images.

"One of the advantages we have with seafloor volcanoes is we really know very well where the magma chamber is," Wilcock said.

"The challenge in the oceans has always been to get good observations of the eruption itself."

All that changed when the Cabled Array was installed and instruments were turned on. Analysis of vibrations leading up to and during the event show an increasing number of small earthquakes, up to thousands a day, in the previous months. The vibrations also show strong tidal triggering, with six times as many earthquakes during low tides as high tides while the volcano approached its eruption.

Once lava emerged, movement began along a newly formed crack, or dike, that sloped downward and outward inside the 2-mile-wide by 5-mile-long caldera.

"There has been a longstanding debate among volcanologists about the orientation of ring faults beneath calderas: Do they slope toward or away from the center of the caldera?" Wilcock said. "We were able to detect small earthquakes and locate them very accurately, and see that they were active while the volcano was inflating."

The two previous eruptions sent lava south of the volcano's rectangular crater. This eruption produced lava to the north. The seismic analysis shows that before the eruption, the movement was on the outward-dipping ring fault. Then a new crack or dike formed, initially along the same outward-dipping fault below the eastern wall of the caldera. The outward-sloping fault has been predicted by so-called "sandbox models," but these are the most detailed observations to confirm that they happen in nature. That crack moved southward along this plane until it hit the northern limit of the previous 2011 eruption.

"In areas that have recently erupted, the stress has been relieved," Wilcock said. "So the crack stopped going south and then it started going north." Seismic evidence shows the crack went north along the eastern edge of the caldera, then lava pierced the crust's surface and erupted inside and then outside the caldera's northeastern edge.

The dike, or crack, then stepped to the west and followed a line north of the caldera to about 9 miles (15 km) north of the volcano, with thousands of small explosions on the way.

"At the northern end there were two big eruptions and those lasted nearly a month, based on when the explosions were happening and when the magma chamber was deflating," Wilcock said.

The activity continued throughout May, then lava stopped flowing and the seismic vibrations shut off. Within a month afterward the earthquakes dropped to just 20 per day.

The volcano has not yet started to produce more earthquakes as it gradually rebuilds toward another eruption, which typically happen every decade or so. The observatory centered on Axial Volcano is designed to operate for at least 25 years. "The cabled array offers new opportunities to study volcanism and really learn how these systems work," Wilcock said. "This is just the beginning."

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New study doubles the estimate of bird species in the world

New research led by the American Museum of Natural History suggests that there are about 18,000 bird species in the world -- nearly twice as many as previously thought. The work focuses on "hidden" avian diversity -- birds that look similar to one another, or were thought to interbreed, but are actually different species. Recently published in the journal PLOS ONE, the study has serious implications for conservation practices.

"We are proposing a major change to how we count diversity," said Joel Cracraft, an author of the study and a curator in the American Museum of Natural History's Department of Ornithology. "This new number says that we haven't been counting and conserving species in the ways we want."

Birds are traditionally thought of as a well-studied group, with more than 95 percent of their global species diversity estimated to have been described. Most checklists used by bird watchers as well as by scientists say that there are roughly between 9,000 and 10,000 species of birds. But those numbers are based on what's known as the "biological species concept," which defines species in terms of what animals can breed together.

"It's really an outdated point of view, and it's a concept that is hardly used in taxonomy outside of birds," said lead author George Barrowclough, an associate curator in the Museum's Department of Ornithology.

For the new work, Cracraft, Barrowclough, and their colleagues at the University of Nebraska, Lincoln, and the University of Washington examined a random sample of 200 bird species through the lens of morphology -- the study of the physical characteristics like plumage pattern and color, which can be used to highlight birds with separate evolutionary histories. This method turned up, on average, nearly two different species for each of the 200 birds studied. This suggests that bird biodiversity is severely underestimated, and is likely closer to 18,000 species worldwide.

The researchers also surveyed existing genetic studies of birds, which revealed that there could be upwards of 20,000 species. But because the birds in this body of work were not selected randomly -- and, in fact, many were likely chosen for study because they were already thought to have interesting genetic variation -- this could be an overestimate. The authors argue that future taxonomy efforts in ornithology should be based on both methods.

"It was not our intent to propose new names for each of the more than 600 new species we identified in the research sample," Cracraft said. "However, our study provides a glimpse of what a future taxonomy should encompass."

Increasing the number of species has implications for preserving biodiversity and other conservation efforts.

"We have decided societally that the target for conservation is the species," said Robert Zink, a co-author of the study and a biologist at the University of Nebraska, Lincoln. "So it follows then that we really need to be clear about what a species is, how many there are, and where they're found."

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