New design points a path to the ‘ultimate’ battery

ultimate-battery-lithium-oxygen
Many of the technologies we use every day have been getting smaller, faster and cheaper each year — with the notable exception of batteries. Apart from the possibility of a smartphone which lasts for days without needing to be charged, the challenges associated with making a better battery are holding back the widespread adoption of two major clean technologies: electric cars and grid-scale storage for solar power. Credit: © Eyematrix / Fotolia

Scientists have developed a working laboratory demonstrator of a lithium-oxygen battery which has very high energy density, is more than 90% efficient, and, to date, can be recharged more than 2000 times, showing how several of the problems holding back the development of these devices could be solved.

Lithium-oxygen, or lithium-air, batteries have been touted as the ‘ultimate’ battery due to their theoretical energy density, which is ten times that of a lithium-ion battery. Such a high energy density would be comparable to that of gasoline — and would enable an electric car with a battery that is a fifth the cost and a fifth the weight of those currently on the market to drive from London to Edinburgh on a single charge.

However, as is the case with other next-generation batteries, there are several practical challenges that need to be addressed before lithium-air batteries become a viable alternative to gasoline.

Now, researchers from the University of Cambridge have demonstrated how some of these obstacles may be overcome, and developed a lab-based demonstrator of a lithium-oxygen battery which has higher capacity, increased energy efficiency and improved stability over previous attempts.

Their demonstrator relies on a highly porous, ‘fluffy’ carbon electrode made from graphene (comprising one-atom-thick sheets of carbon atoms), and additives that alter the chemical reactions at work in the battery, making it more stable and more efficient. While the results, reported in the journal Science, are promising, the researchers caution that a practical lithium-air battery still remains at least a decade away.

“What we’ve achieved is a significant advance for this technology and suggests whole new areas for research — we haven’t solved all the problems inherent to this chemistry, but our results do show routes forward towards a practical device,” said Professor Clare Grey of Cambridge’s Department of Chemistry, the paper’s senior author.

Many of the technologies we use every day have been getting smaller, faster and cheaper each year — with the notable exception of batteries. Apart from the possibility of a smartphone which lasts for days without needing to be charged, the challenges associated with making a better battery are holding back the widespread adoption of two major clean technologies: electric cars and grid-scale storage for solar power.

“In their simplest form, batteries are made of three components: a positive electrode, a negative electrode and an electrolyte,” said Dr Tao Liu, also from the Department of Chemistry, and the paper’s first author.

In the lithium-ion (Li-ion) batteries we use in our laptops and smartphones, the negative electrode is made of graphite (a form of carbon), the positive electrode is made of a metal oxide, such as lithium cobalt oxide, and the electrolyte is a lithium salt dissolved in an organic solvent. The action of the battery depends on the movement of lithium ions between the electrodes. Li-ion batteries are light, but their capacity deteriorates with age, and their relatively low energy densities mean that they need to be recharged frequently.

Over the past decade, researchers have been developing various alternatives to Li-ion batteries, and lithium-air batteries are considered the ultimate in next-generation energy storage, because of their extremely high energy density. However, previous attempts at working demonstrators have had low efficiency, poor rate performance, unwanted chemical reactions, and can only be cycled in pure oxygen.

What Liu, Grey and their colleagues have developed uses a very different chemistry than earlier attempts at a non-aqueous lithium-air battery, relying on lithium hydroxide (LiOH) instead of lithium peroxide (Li2O2). With the addition of water and the use of lithium iodide as a ‘mediator’, their battery showed far less of the chemical reactions which can cause cells to die, making it far more stable after multiple charge and discharge cycles.

By precisely engineering the structure of the electrode, changing it to a highly porous form of graphene, adding lithium iodide, and changing the chemical makeup of the electrolyte, the researchers were able to reduce the ‘voltage gap’ between charge and discharge to 0.2 volts. A small voltage gap equals a more efficient battery — previous versions of a lithium-air battery have only managed to get the gap down to 0.5 — 1.0 volts, whereas 0.2 volts is closer to that of a Li-ion battery, and equates to an energy efficiency of 93%.

The highly porous graphene electrode also greatly increases the capacity of the demonstrator, although only at certain rates of charge and discharge. Other issues that still have to be addressed include finding a way to protect the metal electrode so that it doesn’t form spindly lithium metal fibres known as dendrites, which can cause batteries to explode if they grow too much and short-circuit the battery.

Additionally, the demonstrator can only be cycled in pure oxygen, while the air around us also contains carbon dioxide, nitrogen and moisture, all of which are generally harmful to the metal electrode.

“There’s still a lot of work to do,” said Liu. “But what we’ve seen here suggests that there are ways to solve these problems — maybe we’ve just got to look at things a little differently.”

“While there are still plenty of fundamental studies that remain to be done, to iron out some of the mechanistic details, the current results are extremely exciting — we are still very much at the development stage, but we’ve shown that there are solutions to some of the tough problems associated with this technology,” said Grey.


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The above post is reprinted from materials provided by University of Cambridge. Note: Materials may be edited for content and length.


Journal Reference:

  1. T. Liu, M. Leskes, W. Yu, A. J. Moore, L. Zhou, P. M. Bayley, G. Kim, C. P. Grey. Cycling Li-O2 batteries via LiOH formation and decomposition. Science, 2015; 350 (6260): 530 DOI: 10.1126/science.aac7730

Images of pleasure, winning have unique distracting power

It is hard to ignore positive images. Credit: © Monkey Business / Fotolia
It is hard to ignore positive images.
Credit: © Monkey Business / Fotolia

 

Images related to pleasure or winning attract attention from demanding tasks, while equally intense but negative images and those associated with losing can be fully ignored, finds a new UCL study.

51 volunteers completed attention tasks involving search for ‘target’ items. They were found to be highly distracted by emotional images, whether positive or negative, when the search was easy. However when the search was harder and demanded high focus of attention people were able to completely ignore the negative images, while the positive images continued to be highly distracting.

Positive images included graphic photographs of romantic scenes, happy faces, and neutral faces that were previously associated with winning points in a betting task. Negative images included gory photographs, angry faces and neutral faces previously associated with losing points in the betting task.

The study, published in the journal Emotion, suggests that it is easier to ignore negative images than positive ones when we are focusing on other things.

“If someone is busy, the best way to capture their attention is with something related to pleasure,” explains study author Professor Nilli Lavie (UCL Institute of Cognitive Neuroscience). “For example adverts from charities often use images of suffering to encourage donations. Our study suggests that these images could be overlooked by people who are engaged in other activities such as using their phones, reading the newspaper, or forwarding their TV recordings to resume the program they were watching. To capture the attention from other activities, charities could consider using more positive images such as happy people whose lives have been improved by donations.”

The effect was seen not only with intrinsically positive images but also neutral images that were associated with winning in a betting game. Six neutral face images were used with different odds of winning or losing points. Participants were asked to choose between different pairs to maximise points, but these did not represent real money. By the end of the 15-minute game, the patterns of ‘winning’ and ‘losing’ faces were clear; participants consistently chose faces with high odds of winning and low odds of losing.

“The attention-grabbing power of images associated with winning meaningless points is staggering,” says Professor Lavie. “While people were able to ignore graphic images of mutilated bodies during the more difficult task, neutral, expressionless faces associated with winning still distracted them. People appear to be tuned to the prospects of winning. This could suggest a new way of marketing as any neutral image such as a brand logo can be used to capture attention, if the consumer is offered to play in some betting game and the image is associated with winning.

“The results are also surprising from an evolutionary perspective, as one would expect the brain to pay most attention to negative images because they can indicate potential threats. Our findings may reflect the changing priorities of modern Western society, where we face relatively few immediate threats to our lives. In this safe space, our minds may be more focused on pleasure seeking instead of paying attention to potential harm. The power of positive images and those associated with winning may be a symptom of our competitive, hedonistic society.”


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The above post is reprinted from materials provided by University College London. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rashmi Gupta, Young-Jin Hur, Nilli Lavie. Distracted by Pleasure: Effects of Positive Versus Negative Valence on Emotional Capture Under Load.. Emotion, 2015; DOI: 10.1037/emo0000112

More than 11 moles on your arm could indicate higher risk of melanoma

Naevus (mole) count is one of the most important markers of risk for skin cancer despite only 20 to 40 per cent of melanoma arising from pre-existing moles. Credit: © phanuwatnandee / Fotolia
Naevus (mole) count is one of the most important markers of risk for skin cancer despite only 20 to 40 per cent of melanoma arising from pre-existing moles.
Credit: © phanuwatnandee / Fotolia

Researchers at King’s College London have investigated a new method that could be used by GPs to quickly determine the number of moles on the entire body by counting the number found on a smaller ‘proxy’ body area, such as an arm.

Naevus (mole) count is one of the most important markers of risk for skin cancer despite only 20 to 40 per cent of melanoma arising from pre-existing moles. The risk is thought to increase by two to four per cent per additional mole on the body, but counting the total number on the entire body can be time consuming in a primary care setting.

Previous studies on a smaller scale have attempted to identify mole count on certain body sites as a proxy to accurately estimate the number on the body as a whole and found that the arm was the most predictive.

This study, funded by the Wellcome Trust, used a much larger sample of participants to identify the most useful ‘proxy’ site for a full body mole count as well as the ‘cut off’ number of moles that can be used to predict those at the highest risk of developing skin cancer.

The researchers used data from 3594 female Caucasian twins between January 1995 and December 2003 as part of the TwinsUK study protocol. Twins underwent a skin examination including recording skin type, hair and eye colour and freckles as well as mole count on 17 body sites performed by trained nurses. This was then replicated in a wider sample of male and female participants from a UK melanoma case control study published previously.

Scientists found that the count of moles on the right arm was most predictive of the total number on the whole body. Females with more than seven moles on their right arm had nine times the risk of having more than 50 on the whole body and those with more than 11 on their right arm were more likely to have over 100 on their body in total, meaning they were at a higher risk of developing a melanoma.

These findings could help GPs to more easily identify those at the highest risk of developing a melanoma (skin cancer).

Scientists also found that the area above the right elbow was particularly predictive of the total body count of moles. The legs were also strongly associated with the total count as well as the back area in males.

Lead author, Simone Ribero of the Department of Twin Research & Genetic Epidemiology said: ‘This study follows on from previous work to identify the best proxy site for measuring the number of moles on the body as a whole. The difference here is that it has been done on a much larger scale in a healthy Caucasian population without any selection bias and subsequently replicated in a case control study from a similar healthy UK population, making the results more useful and relevant for GPs.

‘The findings could have a significant impact for primary care, allowing GPs to more accurately estimate the total number of moles in a patient extremely quickly via an easily accessible body part. This would mean that more patients at risk of melanoma can be identified and monitored.’


Story Source:

The above post is reprinted from materials provided by King’s College London. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. Ribero, D. Zugna, S. Osella-Abate, D. Glass, P. Nathan, T. Spector, V. Bataille. Prediction of high naevus count in a healthy UK population to estimate melanoma risk. British Journal of Dermatology, 2015; DOI: 10.1111/bjd.14216

Artificial Skin Lets Person Feel Pressure

Human finger touches robotic finger. The transparent plastic and black device on the golden "fingertip" is the skin-like sensor developed by Stanford engineers. This sensor can detect pressure and transmit that touch sensation to a nerve cell. The goal is to create artificial skin, studded with many such miniaturized sensors, to give prosthetic appendages some of the sensory capabilities of human skin. Credit: Bao Lab
Human finger touches robotic finger. The transparent plastic and black device on the golden “fingertip” is the skin-like sensor developed by Stanford engineers. This sensor can detect pressure and transmit that touch sensation to a nerve cell. The goal is to create artificial skin, studded with many such miniaturized sensors, to give prosthetic appendages some of the sensory capabilities of human skin.
Credit: Bao Lab

Stanford engineers have created a plastic “skin” that can detect how hard it is being pressed and generate an electric signal to deliver this sensory input directly to a living brain cell.

Zhenan Bao, a professor of chemical engineering at Stanford, has spent a decade trying to develop a material that mimics skin’s ability to flex and heal, while also serving as the sensor net that sends touch, temperature and pain signals to the brain. Ultimately she wants to create a flexible electronic fabric embedded with sensors that could cover a prosthetic limb and replicate some of skin’s sensory functions.

Bao’s work, reported today in Science, takes another step toward her goal by replicating one aspect of touch, the sensory mechanism that enables us to distinguish the pressure difference between a limp handshake and a firm grip.

“This is the first time a flexible, skin-like material has been able to detect pressure and also transmit a signal to a component of the nervous system,” said Bao, who led the 17-person research team responsible for the achievement.

Benjamin Tee, a recent doctoral graduate in electrical engineering; Alex Chortos, a doctoral candidate in materials science and engineering; and Andre Berndt, a postdoctoral scholar in bioengineering, were the lead authors on the Science paper.

Digitizing touch

The heart of the technique is a two-ply plastic construct: the top layer creates a sensing mechanism and the bottom layer acts as the circuit to transport electrical signals and translate them into biochemical stimuli compatible with nerve cells. The top layer in the new work featured a sensor that can detect pressure over the same range as human skin, from a light finger tap to a firm handshake.

Five years ago, Bao’s team members first described how to use plastics and rubbers as pressure sensors by measuring the natural springiness of their molecular structures. They then increased this natural pressure sensitivity by indenting a waffle pattern into the thin plastic, which further compresses the plastic’s molecular springs.

To exploit this pressure-sensing capability electronically, the team scattered billions of carbon nanotubes through the waffled plastic. Putting pressure on the plastic squeezes the nanotubes closer together and enables them to conduct electricity.

This allowed the plastic sensor to mimic human skin, which transmits pressure information as short pulses of electricity, similar to Morse code, to the brain. Increasing pressure on the waffled nanotubes squeezes them even closer together, allowing more electricity to flow through the sensor, and those varied impulses are sent as short pulses to the sensing mechanism. Remove pressure, and the flow of pulses relaxes, indicating light touch. Remove all pressure and the pulses cease entirely.

The team then hooked this pressure-sensing mechanism to the second ply of their artificial skin, a flexible electronic circuit that could carry pulses of electricity to nerve cells.

Importing the signal

Bao’s team has been developing flexible electronics that can bend without breaking. For this project, team members worked with researchers from PARC, a Xerox company, which has a technology that uses an inkjet printer to deposit flexible circuits onto plastic. Covering a large surface is important to making artificial skin practical, and the PARC collaboration offered that prospect.

Finally the team had to prove that the electronic signal could be recognized by a biological neuron. It did this by adapting a technique developed by Karl Deisseroth, a fellow professor of bioengineering at Stanford who pioneered a field that combines genetics and optics, called optogenetics. Researchers bioengineer cells to make them sensitive to specific frequencies of light, then use light pulses to switch cells, or the processes being carried on inside them, on and off.

For this experiment the team members engineered a line of neurons to simulate a portion of the human nervous system. They translated the electronic pressure signals from the artificial skin into light pulses, which activated the neurons, proving that the artificial skin could generate a sensory output compatible with nerve cells.

Optogenetics was only used as an experimental proof of concept, Bao said, and other methods of stimulating nerves are likely to be used in real prosthetic devices. Bao’s team has already worked with Bianxiao Cui, an associate professor of chemistry at Stanford, to show that direct stimulation of neurons with electrical pulses is possible.

Bao’s team envisions developing different sensors to replicate, for instance, the ability to distinguish corduroy versus silk, or a cold glass of water from a hot cup of coffee. This will take time. There are six types of biological sensing mechanisms in the human hand, and the experiment described in Science reports success in just one of them.

But the current two-ply approach means the team can add sensations as it develops new mechanisms. And the inkjet printing fabrication process suggests how a network of sensors could be deposited over a flexible layer and folded over a prosthetic hand.

“We have a lot of work to take this from experimental to practical applications,” Bao said. “But after spending many years in this work, I now see a clear path where we can take our artificial skin.”


Story Source:

The above post is reprinted from materials provided by Stanford University. The original item was written by Tom Abate. Note: Materials may be edited for content and length.


Journal Reference:

  1. B.C.K. Tee et al. A skin-inspired organic digital mechanoreceptor. Science, 2015 DOI: 10.1126/science.aaa9306

World’s Lightest Material

the-strongest-material-in-the-world

Boeing says it’s created the lightest metal ever, a microlattice material which it describes as 99.99% air.

The microlattice is a “3D open-cellular polymer structure” and is made up of interconnecting hollow tubes, each one measuring 1000 times thinner than a human hair.

The material is 100 times lighter than styrofoam, making it the lightest and also one of the strongest materials known to science.

Sophia Yang, a research scientist at HRL laboratories who worked with Boeing on the creation of the material says that the metal is 99.99% air. She compares the material to bone, whereby the outside of the bone is rigid while the inside is mostly hollow, creating an open-cellular structure which means it’s remarkably strong as well as extremely lightweight.

The material has been made primarily for use in in aerospace engineering. Engineers intend to use the microlattice for plane interiors in places such as side-panels, overhead cabins, or walkway areas. This would drastically reduce the overall weight of the aircraft, making it more fuel-efficient and cheaper to run.

Yang also highlights the material’s ability to absorb high levels of impact. Using the “egg challenge” as an example, she explains: “You need to drop an egg from 25 stories and protect that egg… What we can do is design the microlattice to absorb the force that the egg feels. So instead of having an egg that’s wrapped in three feet of bubble wrap, now you have a much smaller package that your egg can sit in.”

The microlattice was originally unveiled in November 2011 and was named one of 10 world-changing innovations by Popular Mechanics.

Machines have nothing on mom when it comes to listening

Credit: University of Montreal
Credit: University of Montreal

More than 99% of the time, two words are enough for people with normal hearing to distinguish the voice of a close friend or relative amongst other voices, says the University of Montreal’s Julien Plante-Hébert. His study, presented at the 18th International Congress of Phonetic Sciences, involved playing recordings to Canadian French speakers, who were asked to recognize on multiple trials which of the ten male voices they heard was familiar to them. “Merci beaucoup” turned out to be all they needed to hear.

Plante-Hébert is a voice recognition doctoral student at the university’s Department of Linguistics and Translation. “The auditory capacities of humans are exceptional in terms of identifying familiar voices. At birth, babies can already recognize the voice of their mothers and distinguish the sounds of foreign languages,” Plante-Hébert said. To evaluate these auditory capacities, he created a series of voice “lineups,” a technique inspired by the well-known visual identification procedure used by police, in which a group of individuals sharing similar physical traits are placed before a witness. “A voice lineup is an analogous procedure in which several voices with similar acoustic aspects are presented. In my study, each voice lineup contained different lengths of utterances varying from one to eighteen syllables. Familiarity between the target voice and the identifier was defined by the degree of contact between the interlocutors.” Forty-four people aged 18-65 participated.

Plante-Hébert found that the participants were unable to identify short utterances regardless of their familiarity with the person speaking. However, with utterances of four or more syllables, such as “merci beaucoup,” the success rate was nearly total for very familiar voices. “Identification rates exceed those currently obtained with automatic systems,” he said. Indeed, in his opinion, the best speech recognition systems are much less efficient than auditory system at best, there is a 92% success rate compared to over 99.9% for humans.

Moreover, in a noisy environment, humans can exceed machine-based recognition because of our brain’s ability to filter out ambient noise. “Automatic speaker recognition is in fact the least accurate biometric factor compared to fingerprints or face or iris recognition,” Plante-Hébert said. “While advanced technologies are able to capture a large amount of speech information, only humans so far are able to recognize familiar voices with almost total accuracy,” he concluded.


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The above post is reprinted from materials provided by University of Montreal. Note: Materials may be edited for content and length.

Nobel Prize in Physics for 2015

Illustration of the Sudbury Neutrino Observatory. Credit: Copyright Johan Jarnestad/The Royal Swedish Academy of Sciences
Illustration of the Sudbury Neutrino Observatory.
Credit: Copyright Johan Jarnestad/The Royal Swedish Academy of Sciences

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2015 to Takaaki Kajita Super-Kamiokande Collaboration University of Tokyo, Kashiwa, Japan and Arthur B. McDonald Sudbury Neutrino Observatory Collaboration Queen’s University, Kingston, Canada “for the discovery of neutrino oscillations, which shows that neutrinos have mass.”

Metamorphosis in the particle world

The Nobel Prize in Physics 2015 recognises Takaaki Kajita in Japan and Arthur B. McDonald in Canada, for their key contributions to the experiments which demonstrated that neutrinos change identities. This metamorphosis requires that neutrinos have mass. The discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe.

Around the turn of the millennium, Takaaki Kajita presented the discovery that neutrinos from the atmosphere switch between two identities on their way to the Super-Kamiokande detector in Japan.

Meanwhile, the research group in Canada led by Arthur B. McDonald could demonstrate that the neutrinos from the Sun were not disappearing on their way to Earth. Instead they were captured with a different identity when arriving to the Sudbury Neutrino Observatory.

A neutrino puzzle that physicists had wrestled with for decades had been resolved. Compared to theoretical calculations of the number of neutrinos, up to two thirds of the neutrinos were missing in measurements performed on Earth. Now, the two experiments discovered that the neutrinos had changed identities.

The discovery led to the far-reaching conclusion that neutrinos, which for a long time were considered massless, must have some mass, however small.

For particle physics this was a historic discovery. Its Standard Model of the innermost workings of matter had been incredibly successful, having resisted all experimental challenges for more than twenty years. However, as it requires neutrinos to be massless, the new observations had clearly showed that the Standard Model cannot be the complete theory of the fundamental constituents of the universe.

The discovery rewarded with this year’s Nobel Prize in Physics have yielded crucial insights into the all but hidden world of neutrinos. After photons, the particles of light, neutrinos are the most numerous in the entire cosmos. Earth is constantly bombarded by them.

Many neutrinos are created in reactions between cosmic radiation and Earth’s atmosphere. Others are produced in nuclear reactions inside the Sun. Thousands of billions of neutrinos are streaming through our bodies each second. Hardly anything can stop them passing; neutrinos are nature’s most elusive elementary particles.

Now the experiments continue and intense activity is underway worldwide in order to capture neutrinos and examine their properties. New discoveries about their deepest secrets are expected to change our current understanding of the history, structure and future fate of the universe.

Takaaki Kajita, Japanese citizen. Born 1959 in Higashimatsuyama, Japan. Ph.D. 1986 from University of Tokyo, Japan. Director of Institute for Cosmic Ray Research and Professor at University of Tokyo, Kashiwa, Japan. www.icrr.u-tokyo.ac.jp/about/greeting_eng.html

Arthur B. McDonald, Canadian citizen. Born 1943 in Sydney, Canada. Ph.D. 1969 from Californa Institute of Technology, Pasadena, CA, USA. Professor Emeritus at Queen’s University, Kingston, Canada. www.queensu.ca/physics/arthur-mcdonald

Prize amount: SEK 8 million, to be shared equally between the Laureates.


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Life History of a Dinosaur: Maiasaura

Research published in the journal Paleobiology is showing more about the life history of Maiasaura peeblesorum than any other known dinosaur. Credit: Courtesy Holly Woodward
Research published in the journal Paleobiology is showing more about the life history of Maiasaura peeblesorum than any other known dinosaur.
Credit: Courtesy Holly Woodward

Decades of research on Montana’s state fossil — the “good mother lizard” Maiasaura peeblesorum — has resulted in the most detailed life history of any dinosaur known and created a model to which all other dinosaurs can be compared, according to new research published recently in the journal Paleobiology.

Researchers from Oklahoma State University, Montana State University and Indiana Purdue University used fossils collected from a huge bonebed in western Montana for their study.

“This is one of the most important pieces of paleontology involving MSU in the past 20 years,” said Jack Horner, curator of the Museum of the Rockies at MSU. “This is a dramatic step forward from studying fossilized creatures as single individuals to understanding their life cycle. We are moving away from the novelty of a single instance to looking at a population of dinosaurs in the same way we look at populations of animals today.”

The study was led by Holly Woodward, who did the research as her doctoral thesis in paleontology at MSU. Woodward is now professor of anatomy at Oklahoma State University Center for Health Sciences.

The Paleobiology study examined the fossil bone microstructure, or histology, of 50 Maiasaura tibiae (shin bones). Bone histology reveals aspects of growth that cannot be obtained by simply looking at the shape of the bone, including information about growth rate, metabolism, age at death, sexual maturity, skeletal maturity and how long a species took to reach adult size.

“Histology is the key to understanding the growth dynamics of extinct animals,” Woodward said. “You can only learn so much from a bone by looking at its shape. But the entire growth history of the animal is recorded within the bone.”

A sample of 50 might not sound like much, but for dinosaur paleontologists dealing with an often sparse fossil record, the Maiasaura fossils are a treasure trove.

“No other histological study of a single dinosaur species approaches our sample size,” Woodward said.

With it, the researchers discovered a wealth of new information about how Maiasaura grew up: it had bird-level growth rates throughout most of its life, and its bone tissue most closely resembled that of modern day warm-blooded large mammals such as elk.

Major life events are recorded in the growth of the bones and the rates at which different-aged animals died.

“By studying the clues in the bone histology, and looking at patterns in the death assemblage, we found multiple pieces of evidence all supporting the same timing of sexual and skeletal maturity,” said Elizabeth Freedman Fowler, curator of paleontology at the Great Plains Dinosaur Museum in Malta and adjunct professor at MSU, who performed the mathematical analyses for the study.

Sexual maturity occurred within the third year of life, and Maiasaura reached an average adult mass of 2.3 tonnes in eight years. Life was especially hard for the very young and the old. The average mortality rate for those less than a year of age was 89.9 percent, and 44.4 percent for individuals 8 years and older.

If Maiasaura individuals could survive through their second year, they enjoyed a six-year window of peak physical and reproductive fitness, when the average mortality rate was just 12.7 percent.

“By looking within the bones, and by synthesizing what previous studies revealed, we now know more about the life history of Maiasaura than any other dinosaur and have the sample size to back up our conclusions,” Woodward said. “Our study makes Maiasaura a model organism to which other dinosaur population biology studies will be compared.”

The 50 tibiae also highlighted the extent of individual size variation within a dinosaur species. Previous dinosaur studies histologically examined a small subset of dinosaur bones and assigned ages to the entire sample based on the lengths of the few histologically aged bones.

“Our results suggest you can’t just measure the length of a dinosaur bone and assume it represents an animal of a certain age,” Woodward said. “Within our sample, there is a lot of variability in the length of the tibia in each age group. It would be like trying to assign an age to a person based on their height because you know the height and age of someone else. Histology is the only way to quantify age in dinosaurs.”

Horner, a coauthor on the research and curator of the Museum of the Rockies at MSU where the Maiasaura fossils are reposited, discovered and named Maiasaura in 1979. He made headlines by announcing the world’s first discovery of fossil dinosaur embryos and eggs. Based on the immature development of the baby dinosaur fossils found in nests, Horner hypothesized that they were helpless upon hatching and had to be cared for by parents, so naming the dinosaur Maiasaura, Latin for “good mother lizard.”

Studies that followed revealed aspects of Maiasaura biology including that they were social and nested in colonies; Maiasaura walked on two legs when young and shifted to walking on all four as they got bigger; their preferred foods included rotting wood; and that their environment was warm and semi-arid, with a long dry season prone to drought.

The tibiae included in the Paleobiology study came from a single bonebed in western Montana covering at least two square kilometers. More than 30 years of excavation and thousands of fossils later, the bonebed shows no signs of running dry. Woodward plans to lead annual summer excavations of the Maiasaura bonebed to collect more data.

“Our study kicks off The Maiasaura Life History Project, which seeks to learn as much as possible about Maiasaura and its environment 76 million years ago by continuing to collect and histologically examine fossils from the bonebed, adding statistical strength to the sample,” she said.

“We plan to examine other skeletal elements to make a histological ‘map’ of Maiasaura, seeing if the different bones in its body grew at different rates, which would allow us to study more aspects of its biology and behavior. We also want to better understand the environment in which Maiasaura lived, including the life histories of other animals in the ecosystem,” she added.

The Maiasaura Life History Project will also provide opportunities for college-aged students accompanying Woodward in her excavations to learn about the fields of ecology, biology and geology, thereby encouraging younger generations to pursue careers in science.

In addition to Woodward, Horner and Freedman Fowler, James Farlow, professor emeritus of Geology at Indiana Purdue University, contributed to the Paleobiology paper.


Story Source:

The above post is reprinted from materials provided by Montana State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Holly N. Woodward, Elizabeth A. Freedman Fowler, James O. Farlow, John R. Horner. Maiasaura, a model organism for extinct vertebrate population biology: a large sample statistical assessment of growth dynamics and survivorship. Paleobiology, 2015; 1 DOI: 10.1017/pab.2015.19

Virtual reality for mice teaches scientists about navigation

A mouse is ready to enter a virtual-reality system where its brain can be imaged while it thinks it’s running through a maze.
A mouse is ready to enter a virtual-reality system where its brain can be imaged while it thinks it’s running through a maze.

 

Scientists can now observe the brains of lab animals in microscopic detail as the animals go about some action. A technique called two-photon imaging, in particular, allows neuroscientists to watch thousands of neurons working in concert to encode information.

The trouble is, two-photon imaging requires the animal’s head to stay fixed in place. That would seem to preclude watching the brain as the animal does anything of much interest.

One creative solution is virtual reality—a computer-generated environment experienced through a headset. A few years ago neuroscientists started designing tiny virtual-reality systems to fool mice into thinking they were navigating a maze when they were really running on the top of a large ball, their heads fixed in position.

Until now, however, mice didn’t run on the ball until they’d had weeks of training. Jeremy Freeman, working with colleague Nicholas Sofroniew and others at the HHMI Janelia Research Campus in Virginia, created a virtual maze the mice seem to understand right away: they navigate through virtual corridors without training. It’s designed to exploit the way mice navigate in nature, Freeman says. Instead of relying primarily on their eyes, mice rely heavily on their whiskers to feel their way through the world.

In the whisker-oriented virtual reality, the walls move to give the mouse the illusion that it is running down winding corridors, he says. But the whole time, the rodent’s head is stationary.

This approach doesn’t translate neatly to the human world. Mice rely heavily on their whiskers to get around, and the neural imaging requires genetically altering mice to produce fluorescent proteins. However, this mouse-sized VR could still shed plenty of light on autism and other conditions that affect decisions, learning and the senses.


Story Source:

The above post is reprinted from materials provided by MIT Technology Review. Note: Materials may be edited for content and length.

Making batteries with portabella mushrooms

Diagram showing how mushrooms are turned into a material for battery anodes. Credit: Image courtesy of University of California - Riverside
Diagram showing how mushrooms are turned into a material for battery anodes.
Credit: Image courtesy of University of California – Riverside

Can portabella stop cell phone batteries from degrading over time?

Researchers at the University of California, Riverside Bourns College of Engineering think so.

They have created a new type of lithium-ion battery anode using portabella mushrooms, which are inexpensive, environmentally friendly and easy to produce. The current industry standard for rechargeable lithium-ion battery anodes is synthetic graphite, which comes with a high cost of manufacturing because it requires tedious purification and preparation processes that are also harmful to the environment.

With the anticipated increase in batteries needed for electric vehicles and electronics, a cheaper and sustainable source to replace graphite is needed. Using biomass, a biological material from living or recently living organisms, as a replacement for graphite, has drawn recent attention because of its high carbon content, low cost and environmental friendliness.

UC Riverside engineers were drawn to using mushrooms as a form of biomass because past research has established they are highly porous, meaning they have a lot of small spaces for liquid or air to pass through. That porosity is important for batteries because it creates more space for the storage and transfer of energy, a critical component to improving battery performance.

In addition, the high potassium salt concentration in mushrooms allows for increased electrolyte-active material over time by activating more pores, gradually increasing its capacity.

A conventional anode allows lithium to fully access most of the material during the first few cycles and capacity fades from electrode damage occurs from that point on. The mushroom carbon anode technology could, with optimization, replace graphite anodes. It also provides a binderless and current-collector free approach to anode fabrication.

“With battery materials like this, future cell phones may see an increase in run time after many uses, rather than a decrease, due to apparent activation of blind pores within the carbon architectures as the cell charges and discharges over time,” said Brennan Campbell, a graduate student in the Materials Science and Engineering program at UC Riverside.

The research findings were outlined in a paper, “Bio-Derived, Binderless, Hierarchically Porous Carbon Anodes for Li-ion Batteries,” published in the journal Scientific Reports. It was authored by Cengiz Ozkan and Mihri Ozkan, both professors in the Bourns College of Engineering, and three of their current or former graduate students: Campbell, Robert Ionescu and Zachary Favors.

Nanocarbon architectures derived from biological materials such as mushrooms can be considered a green and sustainable alternative to graphite-based anodes, said Cengiz Ozkan, a professor of mechanical engineering and materials science and engineering.

The nano-ribbon-like architectures transform upon heat treatment into an interconnected porous network architecture which is important for battery electrodes because such architectures possess a very large surface area for the storage of energy, a critical component to improving battery performance.

One of the problems with conventional carbons, such as graphite, is that they are typically prepared with chemicals such as acids and activated by bases that are not environmentally friendly, said Mihri Ozkan, a professor of electrical and computer engineering. Therefore, the UC Riverside team is focused on naturally-derived carbons, such as the skin of the caps of portabella mushrooms, for making batteries.

It is expected that nearly 900,000 tons of natural raw graphite would be needed for anode fabrication for nearly six million electric vehicle forecast to be built by 2020. This requires that the graphite be treated with harsh chemicals, including hydrofluoric and sulfuric acids, a process that creates large quantities of hazardous waste. The European Union projects this process will be unsustainable in the future.

The Ozkan’s research is supported by the University of California, Riverside.

This paper involving mushrooms is published just over a year after the Ozkan’s labs developed a lithium-ion battery anode based on nanosilicon via beach sand as the natural raw material. Ozkan’s team is currently working on the development of pouch prototype batteries based on nanosilicon anodes.

The UCR Office of Technology Commercialization has filed patents for the inventions above.


Story Source:

The above post is reprinted from materials provided by University of California – Riverside. The original item was written by Sean Nealon. Note: Materials may be edited for content and length.


Journal Reference:

  1. Brennan Campbell, Robert Ionescu, Zachary Favors, Cengiz S. Ozkan, Mihrimah Ozkan. Bio-Derived, Binderless, Hierarchically Porous Carbon Anodes for Li-ion Batteries. Scientific Reports, 2015; 5: 14575 DOI: 10.1038/srep14575