ENHANCING THE POWER OF BATTERIES
Batteries might gain a boost in power capacity as a result of a new finding from researchers at MIT. They found that using carbon nanotubes for one of the battery's electrodes produced a significant increase — up to tenfold — in the amount of power it could deliver from a given weight of material, compared to a conventional lithium-ion battery. Such electrodes might find applications in small portable devices, and with further research might also lead to improved batteries for larger, more power-hungry applications.
To produce the powerful new electrode material, the team used a layer-by-layer fabrication method, in which a base material is alternately dipped in solutions containing carbon nanotubes that have been treated with simple organic compounds that give them either a positive or negative net charge. When these layers are alternated on a surface, they bond tightly together because of the complementary charges, making a stable and durable film.
The findings, by a team led by Associate Professor of Mechanical Engineering and Materials Science and Engineering Yang Shao-Horn, in collaboration with Bayer Chair Professor of Chemical Engineering Paula Hammond, are reported in a paper published June 20 in the journal Nature Nanotechnology. The lead authors are chemical engineering student Seung Woo Lee PhD '10 and postdoctoral researcher Naoaki Yabuuchi.
Batteries, such as the lithium-ion batteries widely used in portable electronics, are made up of three basic components: two electrodes (called the anode, or negative electrode, and the cathode, or positive electrode) separated by an electrolyte, an electrically conductive material through which charged particles, or ions, can move easily. When these batteries are in use, positively charged lithium ions travel across the electrolyte to the cathode, producing an electric current; when they are recharged, an external current causes these ions to move the opposite way, so they become embedded in the spaces in the porous material of the anode.
In the new battery electrode, carbon nanotubes — a form of pure carbon in which sheets of carbon atoms are rolled up into tiny tubes — "self-assemble" into a tightly bound structure that is porous at the nanometer scale (billionths of a meter). In addition, the carbon nanotubes have many oxygen groups on their surfaces, which can store a large number of lithium ions; this enables carbon nanotubes for the first time to serve as the positive electrode in lithium batteries, instead of just the negative electrode.
This "electrostatic self-assembly" process is important, Hammond explains, because ordinarily carbon nanotubes on a surface tend to clump together in bundles, leaving fewer exposed surfaces to undergo reactions. By incorporating organic molecules on the nanotubes, they assemble in a way that "has a high degree of porosity while having a great number of nanotubes present," she says.
Lithium batteries with the new material demonstrate some of the advantages of both capacitors, which can produce very high power outputs in short bursts, and lithium batteries, which can provide lower power steadily for long periods, Lee says. The energy output for a given weight of this new electrode material was shown to be five times greater than for conventional capacitors, and the total power delivery rate was 10 times that of lithium-ion batteries, the team says. This performance can be attributed to good conduction of ions and electrons in the electrode, and efficient lithium storage on the surface of the nanotubes.
In addition to their high power output, the carbon-nanotube electrodes showed very good stability over time. After 1,000 cycles of charging and discharging a test battery, there was no detectable change in the material's performance.
The electrodes the team produced had thicknesses up to a few microns, and the improvements in energy delivery only were seen at high-power output levels. In future work, the team aims to produce thicker electrodes and extend the improved performance to low-power outputs as well, they say. In its present form, the material might have applications for small, portable electronic devices, says Shao-Horn, but if the reported high-power capability were demonstrated in a much thicker form — with thicknesses of hundreds of microns rather than just a few — it might eventually be suitable for other applications such as hybrid cars.
While the electrode material was produced by alternately dipping a substrate into two different solutions — a relatively time-consuming process — Hammond suggests that the process could be modified by instead spraying the alternate layers onto a moving ribbon of material, a technique now being developed in her lab. This could eventually open the possibility of a continuous manufacturing process that could be scaled up to high volumes for commercial production, and could also be used to produce thicker electrodes with a greater power capacity. "There isn't a real limit" on the potential thickness, Hammond says. "The only limit is the time it takes to make the layers," and the spraying technique can be up to 100 times faster than dipping, she says.
Lee says that while carbon nanotubes have been produced in limited quantities so far, a number of companies are currently gearing up for mass production of the material, which could help to make it viable for large-scale battery manufacturing.
Yury Gogotsi, professor of materials science at Drexel University, says, "This is an important achievement, because there is a need for energy storage in a thin-film format for powering portable electronic devices and for flexible, wearable electronics. Bridging the performance gap between batteries and electrochemical capacitors is an important task, and the MIT group has made an important step in this direction."
Some uncertainties remain, however. "The electrochemical performance data presented in the article may only be valid for relatively thin films with no packaging," Gogotsi says, pointing out that the measured results were for just the individual electrode, and results might be different for a whole battery with its multiple parts and outer container. "The question remains whether the proposed approach will work for much thicker conventional electrodes, used in devices that are used in hybrid and electric cars, wind power generators, etc." But, he adds, if it does turn out that this new system works for such thicker electrodes, "the significance of this work will increase dramatically."
(Photo: MIT)
STUDY FINDS THAT CARING FOR AN ELDERLY, SICK SPOUSE SOMETIMES HAS POSITIVE ELEMENTS
Etiquetas: Psychology
Although long-term care of sick or disabled loved ones is widely recognized as a threat to the caregiver's health and quality of life, a new study led by University at Buffalo psychologist Michael Poulin, PhD, finds that in some contexts, helping valued loved ones may promote the well being of helpers.
"Does a Helping Hand Mean a Heavy Heart?," published in the journal Psychology and Aging (2010, Vol. 25., No. 1), reports on a study by Poulin and five co-authors from the University of Michigan Department of Internal Medicine, which closely analyzed helping behavior and well-being among 73 spousal caregivers, many of them elderly.
Poulin, an assistant professor of psychology, says the study team wanted to learn if there were some positive aspects of caregiving, aspects that did not provoke the burnout, high stress and poor health associated with being a caregiver. If so, they wanted to know why these aspects had a positive effect.
They learned that despite the burdensome nature of their role, caregivers experience more positive emotions and fewer negative emotions when they engage in "active care" like feeding, bathing, toileting and otherwise physically caring for the spouse.
"Our data don't tell us exactly what psychological processes are responsible," he says, "but we hypothesize that people may be hardwired so that actively attending to the concrete needs and feelings of others reduces our personal anxiety."
The study found that passive care, on the other hand, which requires the spouse to simply be nearby in case anything should go wrong, provokes negative emotions in the caretaker, and leads to fewer positive emotions.
The study involved 73 subjects (mean age was 71.5 years, age range was 35-89 years) who were providing full-time home care to an ailing spouse. Participants carried Palm Pilots that beeped randomly to signal them to report how much time they had spent actively helping and/or being on call since the last beep, the activities they actually engaged in and their emotional state at that moment.
The researchers found no moderating effects of age on the association between helping and well-being. In other words, helping predicted positive and negative effects similarly for adults of all ages. One variable that did affect outcome was the level of perceived interdependence with the spouse experienced by the caregiver -- that is, the extent to which caregivers viewed themselves as sharing a mutually beneficial relationship with their spouse.
"For interdependent couples, the positive effects of active care were particularly strong," Poulin says, adding that this outcome supports the prediction that "individuals should derive the greatest satisfaction out of helping those with whom they perceive a shared physical or emotional fate."
Poulin says study findings have broad implications for research on caregiving and for research on helping behavior more generally, especially in the aging context.
"Overall," he says, "we wouldn't say that caring for an ailing loved one is going to be good for you or healthy for you, but certain activities may be beneficial, especially in high-quality relationships."
Researchers and social scientists want government or other agencies to provide respite for caregivers, which would be a good thing, Poulin says, "but as this study demonstrates, it is extremely important that caretakers receive the right kind of relief at the right time -- perhaps less time off from active care duties, and more time off from the onerous task of passively monitoring an ailing loved one."
BABIES' FIRST BACTERIA DEPEND ON BIRTHING METHOD
Etiquetas: Biology
A new study indicates different delivery methods of newborn babies has a big effect on the types of microbial communities they harbor as they emerge into the world, findings with potential implications for the heath of infants as they grow and develop.
The study, led by the University of Puerto Rico and involving the University of Colorado at Boulder and two Venezuelan institutes, showed that babies delivered vaginally had bacterial communities resembling their mother's vaginal bacteria, while Caesarian section newborns had common skin bacterial communities. Researchers believe many of the different microbial communities residing on humans -- each of which is personally unique -- may help protect individuals from various diseases.
The new findings establish an important baseline for tracking the succession of bacterial communities on babies and their associated effects on human health, said co-lead study author Maria Dominguez-Bello of the University of Puerto Rico.
The new study appears in the June 21 issue of the Proceedings of the National Academy of Sciences. Former CU-Boulder researcher Elizabeth Costello, now at Stanford University, was co-lead author on the study. Co-authors included CU-Boulder Assistant Professor Noah Fierer, CU-Boulder Assistant Professor Rob Knight, Monica Contreras of the Venezuelan Institute for Scientific Research and Magda Magris of the Amazonic Center for Research and Control of Tropical Diseases in Venezuela.
Dominguez-Bello said the bacterial communities of C-section babies were dominated by species from the Staphylococcus genus, most of which are harmless but a few of which can cause severe infections. "These differences we are seeing in this study might be related with increased health risks in C-section babies, although more research is needed," she said.
Previous studies indicate babies born via C-section can be more susceptible to certain pathogens, allergies and asthma than newborns born vaginally. The PNAS study results may help explain the higher incidence of Methicillin-resistant Staphylococcus aureus, or MRSA, in C-section babies, a hard-to-treat bacterial infection that has been increasing in hospitals and clinics in recent years, according to the researchers.
In a 2004 study undertaken in Chicago and Los Angeles County hospitals, between 64 percent and 82 percent of reported cases of MRSA skin infections in newborns occurred in C-section infants. While the World Health Organization has recommended the percentage of births via C-section not exceed 15 percent in any country because of potential medical complications, the rate is much higher in a number of countries, including China at nearly 50 percent and the United States at about 30 percent.
Human microbial communities play an important role in digestion and immune health and are believed to collectively endow us with the essential traits we rely on for such functions, according to the research team. One possibility is that the direct transmission of a mother's vaginal bacteria onto newborns may act as a defense against diseases by limiting the colonization of more harmful pathogens, they said.
In a related 2009 study led by Knight, researchers developed the first atlas of microbial diversity across the human body in adults, charting wide variations in microbe populations from the forehead and feet to noses and navels of individuals -- differences that were not yet apparent in the PNAS newborn study. One goal of the human bacterial studies is to find out what is normal for healthy people, which should provide a baseline for studies looking at human disease states, said Knight.
"The prospects of learning how differences in individual human microbial communities can be used as a diagnostic tool in biomedicine is frankly quite exciting," said Knight of CU-Boulder's chemistry and biochemistry department. "With these new data on babies, we now have a second point in time for comparison."
"In a sense, the skin of newborn infants is like freshly tilled soil that is awaiting seeds for planting -- in this case bacterial communities," said Fierer of CU-Boulder's ecology and evolutionary biology department. "The microbial communities that cluster on newborns essentially act as their first inoculation."
Fierer, also a fellow at CU's Cooperative Institute for Research in Environmental Sciences, said that during vaginal births "it appears that the newborns pick up the bacteria from the mothers on the way out. But in C-sections, the bacterial communities of infants could come from the first person to handle the baby, perhaps the father."
The new study has allowed the researchers "to capture the first moments in time" of infant bacterial communities, said Costello, a former CU-Boulder postdoctoral researcher. "The challenge now is to fill in the rest of the story by tracking microbial communities in infants to toddlers to children and adults over weeks, months and years to see how they evolve and change," she said.
The PNAS study included nine women from 21 to 33 years old and 10 newborns and was undertaken at the Puerto Ayacucho Hospital in Amazonas State, Venezuela. The babies were sampled within 24 hours of birth by swabbing their mouths and skin and by taking samples from their upper throats and gastrointestinal tracts, said Costello. The research team then used a powerful gene sequencing technique to simultaneously analyze all of the bacteria.
The effort involved isolating and amplifying tiny bits of microbial DNA, then building complementary DNA strands with a high-powered sequencing machine that allowed the team to pool hundreds of samples together in single sequencing runs to identify different families and genera of bacteria, said Knight.
"While the cost of gene sequencing is dropping rapidly, new techniques are allowing us to speed up the process at the same time," said Knight. "We can now foresee a time when such genetic sequencing could be used in relatively small biomedical laboratories in developing countries."
(Photo: Alan Bruce)
University of Colorado at Boulder
BODY-IMAGE DISTORTION PREDICTS ONSET OF UNSAFE WEIGHT-LOSS BEHAVIORS
Normal weight and underweight teenage girls who falsely believe they are overweight are at significantly greater risk of succumbing to unnecessary and unsafe weight-loss behaviors than girls who can accurately assess their weight status, according to new research by a University of Illinois expert in eating disorders and body-image perception.
Janet M. Liechty, a professor of social work and of medicine at Illinois, says that body-image distortion, rather than the more commonly used measure of body dissatisfaction, may be a better screening tool to help identify non-overweight girls at risk for unsafe weight-loss practices.
"Body-image distortion appears to be a more discriminating indicator of distress than body dissatisfaction, but it's not something that's typically screened for by health-care providers," Liechty said.
"Usually, teens and their parents only get weight-related feedback from the doctor when the child is overweight. But kids of any weight can struggle with body-image, and poor body-image can negatively affect medical outcomes in ways we often don't recognize."
Childhood obesity is an important public health concern, but if the emphasis is only on children who are overweight, signs of body-image distress among normal weight kids could be overlooked, Liechty says. If left unaddressed, those problems could eventually translate into unhealthy weight-loss behaviors, disordered eating and future weight problems.
"Body-image distortion is something we can begin to screen for to identify teens at risk for unsafe weight-loss behaviors," she said.
Liechty's research, published in the Journal of Adolescent Health, examined the relationship between body-image distortion and three types of weight-loss behaviors – exercise, dieting, and extreme ways of losing weight such as laxatives, diet pills and purging.
Culling from a longitudinal sample of more than 5,000 non-overweight adolescent girls in the U.S. whose body-mass index was less than the 85th percentile, Liechty compared the teens' actual, objective weight status with what they believed their weight status to be, and looked for discrepancies. If the teens perceived themselves to be overweight when they actually were not, the discrepancy was flagged as overestimation, or body-image distortion.
To examine how overestimation of weight status affected future weight-loss behaviors, Liechty employed logistic regression analysis to predict the onset of the three types of weight-loss behaviors one year later. She discovered that body-image distortion predicts the onset of dieting, and the onset of extreme and unsafe ways to lose weight.
"What this means is, a girl with a distorted body-image is at much greater risk for resorting to unsafe dieting and extreme weight-loss methods than a girl without
body-image distortion, even if she doesn't need to lose weight," Liechty said.
This discovery highlights the importance of cultivating an accurate and positive body-image throughout the teenage years, and of being wary of dieting and extreme methods to lose weight among teens, which are somewhat of a trap, Liechty says.
"This study suggests that if otherwise healthy, non-overweight girls begin using a type of potentially unsafe weight-loss strategy, such as dieting or an extreme method, the odds that they will continue to use that method one year later increase from three to 11 times, " she said.
In other words, if a teen starts down a path of risky weight-loss practices, they're much more likely to continue using that method.
"It doesn't just fade away or stop all of a sudden," Liechty said. "That's why early detection of risk factors such as body-image distortion, and prevention of unnecessary dieting and unsafe weight-loss methods, is the key to pre-empting unhealthy behaviors. We need to educate girls and their parents that fad diets, quick-fix promises, and extreme weight-loss methods are a hoax. They don't work over the long term and they might do harm."
Compared to body dissatisfaction – which has been positively correlated with eating disorders, depression and high-risk behaviors among adolescent girls – body-image distortion may be a better red flag for unsafe weight-loss among teens.
"Body-image is often measured as body-image satisfaction, which is how satisfied you feel about your body," she said. "While that's important, the problem with using that measure is that some studies show that 50 to 80 percent of women are dissatisfied with their bodies. That kind of ubiquitous discontent doesn't give a very specific measure of body-image distress. It turns out that body-image distortion may be a more useful screening tool for counselors, parents or health-care providers."
In contrast to dieting and extreme methods of weight-loss, Liechty's research also discovered that body-image distortion has no relationship to girls' use of exercise as a primary way to lose weight, suggesting that body-image distortion motivates girls to use unsafe but not safe methods of weight control.
This is important to know, Liechty said, because exercise is a standard recommendation for healthy adolescent weight management, and it has many health benefits such as cardio-respiratory fitness and improved mood.
"Choosing a lifestyle that's sustainable and healthy – where the fuel intake matches the output – is really the safest long-term plan for weight management," Liechty said.
"Even though excessive exercise or exercise addiction can become a problem for a small percentage of people, staying physically active is an important ingredient of lifetime weight management. But if we exercise out of addiction or a punitive attitude toward our bodies, it's associated with depression and anxiety. So the attitude and the relationship with self and with body matter a lot in how we approach taking care of ourselves."
Liechty says her findings underscore the urgency for prevention efforts that foster positive and accurate body-image among adolescent girls.
"The best method of weight control is to focus on lifestyle changes and not on radical approaches, because extreme methods wreak havoc with our body chemistry as well as our attitude toward food and toward our bodies," Liechty said.
Dieting, especially what Liechty calls "teenage-style dieting," and extreme weight-loss methods can be risky business.
"They tend to be all-or-nothing, which often leads to cycles of restricting and bingeing. Ironically, other research has shown that this type of dieting among children and teens usually leads to weight gain later in life."
Learning healthy weight-loss and maintenance behaviors is important because bad habits can be addictive, leading to lifelong struggles with eating, Liechty said.
Overweight teens who desire to lose weight need support and a sensible, sustainable plan, Liechty says.
"Parents can encourage healthy eating and exercise habits from the start by leading by example, but if teens want to lose weight, parents should take them to the doctor or health-care professional and discuss how much they should lose, at what pace, and how to do it safely in a careful, planned way," she said.
If teens don't need to lose weight, they should avoid fad diets, ignore quick weight-loss promises, and not get sucked into trying extreme methods like diet pills and purging.
"The underlying issue is our relationship with food and our bodies," Liechty said. "A distorted view of one's weight status makes one more vulnerable to using unsafe weight-loss behaviors. The key is to cultivate a positive, realistic, and appreciative relationship with your body regardless of your weight, then get support to develop eating and activity habits that balance input and output, and that you can live with for long time."
NAVAL RESEARCH LABORATORY/GEORGE MASON UNIVERSITY TEAM OBSERVES RECORD-LOW DENSITIES IN UPPER ATMOSPHERE
Etiquetas: Geophysics
A team of scientists from the Naval Research Laboratory and George Mason University reports that the Earth's upper atmosphere has recently experienced the lowest density in 43 years. The team has published its findings in a paper entitled "Record-low thermospheric density during the 2008 solar minimum" that appeared in Geophysical Research Letters in June 2010.
The team of Dr. John Emmert and Dr. Judith Lean from NRL's Space Science Division and Dr. Michael Picone from George Mason University were studying the Earth's upper atmosphere between 200 and 600 km altitude. Although the air density at these altitudes is only about one-billionth of that at the Earth's surface, it provides sufficient drag on Low Earth Orbit (LEO) objects to cause their eventual reentry. "An operational consequence of this important new finding is that LEO satellites, including debris, may remain in orbit longer than expected," explains Emmert.
To describe their results, the researchers pointed out that the air density at orbital altitudes is ultimately linked to the temperature of the upper atmosphere. A hotter upper atmosphere will expand in vertical extent and increase the air density at a given altitude. The two major factors that control upper atmosphere temperatures are heating via absorption of ultraviolet (UV) radiation from the Sun, and cooling via CO2 infrared emission.
The Sun was unusually quiet during the prolonged solar minimum of 2007-2009, and the research team found that the associated reduction in solar UV heating can partly explain the reduction in density. Increasing concentrations of CO2 near the Earth's surface are likely making their way into the upper atmosphere and are thus increasing the upper atmosphere cooling efficiency. However, it is not yet clear whether the combination of reduced solar UV heating and enhanced CO2 cooling can fully account for the occurrence of the anomalously low thermospheric density, and the researchers suggested that changes in upper atmospheric chemistry and composition may have also contributed to the record-low density.
(Photo: NRL)
NEW ROLE FOR ANCIENT CLOCK
The pancreas has its own molecular clock. Now, for the first time, a Northwestern University study has shown this ancient circadian clock regulates the production of insulin. If the clock is faulty, the result is diabetes.
The researchers show that insulin-secreting islet cells in the pancreas, called beta-cells, have their own dedicated clock. The clock governs the rhythmic behavior of proteins and genes involved in insulin secretion, with oscillations over a 24-hour cycle.
The findings, published (June 18) by the journal Nature, shine a light on a system that hasn't been recognized as having a strong effect on the process of glucose homeostasis.
"This is the first evidence of how the circadian clock may affect the development of diabetes," said Joe Bass, M.D., associate professor of medicine at Feinberg School of Medicine and of neurobiology and physiology at the Weinberg College of Arts and Sciences. "The biological programs in animals for harvesting energy -- much like the photosynthesis of plants -- are under control of the clock. Our findings will help us figure out the causes of glucose abnormalities, but we still have a lot to learn."
The research, led by Bass and Biliana Marcheva, a doctoral candidate in Bass' lab and first author of the paper, represents many years of work and involved key collaborators Louis H. Philipson of the University of Chicago, Joseph S. Takahashi of the University of Texas Southwestern Medical Center and Seth D. Crosby of the Washington University School of Medicine.
In their study, the researchers knocked out the clock genes in islet beta-cells in mice and found the animals developed impaired glucose tolerance and abnormally low levels of insulin and went on to develop diabetes. The clock of the beta-cell coordinates glucose management, and the loss of the clock inhibited the cells from secreting insulin.
"The variation we see in insulin secretion in humans and susceptibility to diabetes is likely related to this clock mechanism," said Bass, an endocrinologist trained in molecular genetics. "There is an association in the changes of the cycling of the clock within the pancreas itself and disease. The next question is, can we modulate this?"
By isolating the pancreas and using bioluminescence imaging (which relies on a protein found in the firefly), the researchers determined that a circadian clock is expressed autonomously in the pancreas. The visual proof is shown in a short video they produced of the beating clock in live insulin-producing cells of the pancreas. The cells emitted light once every 24 hours over a sustained period of time. See video below.
"It's important to remember that body clocks are ancient mechanisms that regulate fundamental biological systems important to health, such as insulin secretion, the time we go to bed, the time we get up and the time we get hungry," Bass said.
The body's primary circadian clock resides deep in the brain, in the suprachiasmatic nuclei, but local biological clocks also are found in tissues throughout the body, including the pancreas, lungs, liver, heart and skeletal muscles. The clocks operate on a 24-hour, circadian (Latin for "about a day") cycle that governs functions such as sleeping and waking, rest and activity, fluid balance, body temperature, cardiac output, oxygen consumption, metabolism and endocrine gland secretion.
The impact of diabetes on health and economics is sobering. According to the American Diabetes Association, more than 23 million adults and children in the United States have a form of diabetes, and at least 57 million have prediabetes; the total cost of diagnosed diabetes (medical costs as well as disability, work loss and early death) is at least $174 billion; and diabetes is the seventh-leading cause of death in the country.
BATTLE OF THE SEXES EXISTS IN THE PLANT WORLD TOO
Research led by the University of Bath has discovered that plants, like animals, also have a battle of the sexes when it comes to raising their offspring.
Their findings could open new avenues to increase crop yields and improve food security for an ever-growing global human population.
Since mothers give birth to young, they must invest more of their resources into producing offspring than fathers.
For mothers, it's a balance between giving enough resources to keep their babies healthy, but still making as many babies as they can. In contrast, it benefits fathers to have young that are as large as possible and more likely to survive.
The researchers, from the Universities of Bath, Exeter and the Albrecht von Haller Institute for Plant Sciences in Germany, have now shown that this parental struggle also exists in plants.
The study, funded by the Natural Environment Research Council (NERC) and the Biotechnology & Biological Sciences Research Council (BBSRC), and published in the Proceedings of the Royal Society B, shows for the first time that male plants can influence the size of seeds.
Using the model plant Arabidopsis, they bred female plants with a variety of different male plants and measured the size of seeds produced with each pairing.
They found that crossing the female plant with a specific strain, or genotype, of male plant produced bigger seeds, allowing the father to have more healthy offspring at the cost of the mother.
Dr Paula Kover, Senior Lecturer at the University of Bath, explained: "Seed size can make a huge difference to whether a seedling is likely to survive, so you would imagine that there would be an optimum seed size for mothers to produce, balancing the likelihood of survival with the cost in energy of producing them.
"However, we see a lot of variation in seed size. The reason for this is a long-standing debate.
"Previously it was thought that seed size was controlled solely by the mother's genes, but for the first time we've shown clearly that genes passed on from the father plant can also have an effect on seed size.
"The next step will be to identify the specific genes that influence seed size. Previously plant breeders only considered the mother's genes in the breeding process, so this study could open the door on a whole new group of genes that could increase crop yield."
Dr Clarissa House, from the University of Exeter, added: "Relatively few studies have been able to distinguish between the influence of paternal genotypes for offspring fitness and maternal effects. Our study clearly shows that paternal genes are important."
(Photo: dmswart)
LCD TELEVISION WASTE COULD HELP PREVENT BACTERIAL INFECTIONS
Etiquetas: Chemistry
The fastest growing waste in the EU could soon be helping to combat hospital infections, according to scientists at the University of York.
Researchers at the University's Department of Chemistry have discovered a way of transforming the chemical compound polyvinyl-alcohol (PVA), which is a key element of television sets with liquid crystal display (LCD) technology, into an anti-microbial substance that destroys infections such as Escherichia coli and some strains of Staphylococcus aureus.
The York research team had earlier found a method of recovering PVA from television screens and transforming it into a substance which, due to its compatibility with the human body, could be suitable for use in tissue scaffolds that help parts of the body regenerate. It could also be used in pills and dressings that are designed to deliver drugs to particular parts of the body.
Dr Hunt, of the York Green Chemistry Centre of Excellence, said: "The influence of LCDs on modern society is dramatic – it is estimated that 2.5 billion LCDs are approaching the end of their life, and they are the fastest growing waste in the European Union.
"But we can add significant value this waste. By heating then cooling the PVA and then dehydrating it with ethanol we can produce a high surface area mesoporous material that has great potential for use in biomedicine.
"Now we have gone a step further by enhancing its anti-microbial properties through the addition of silver nanoparticles, with the result being that it can destroy bacterial infections such as E.coli. Potentially, it could be used in hospital cleaning products to help to reduce infections."
The project's next steps will be to test the PVA-based substance against commercial compounds to determine relative effectiveness, and to secure approval from regulatory agencies regarding the suitability of silver nanoparticles for human health applications.
FAMED HOMINID "LUCY" NO LONGER ALONE
Within the coarsening base of an ancient mudstone exposure in the Afar Region of Ethiopia, researchers say they found evidence that provides new information about the best-known early human ancestor, Australopithecus afarensis.
Yohannes Haile-Selassie--curator and head of physical anthropology at the Cleveland Museum of Natural History--and an international team of scientists dug up a 3.6 million-year-old partial skeleton of the same species as the famed hominid "Lucy." It's only the second partial skeleton of A. afarensis to be recovered; it's 400,000 years older than Lucy and it's male. But just as important, the fossil remains provide conclusive proof that A. afarensis could walk upright freely without the use of its hands.
"The KSD skeleton is long sought fossil evidence," said Haile-Selassie. [KSD is shorthand for 'Korsi Dora,' the name of the locality where the skeleton was found.] "It complements the Laetoli footprints and incontrovertibly shows A. afarensis was an obligate bipedal since its first appearance in the fossil record."
The new skeleton's scientific designation is KSD-VP-1/1. Researchers recovered the skeleton as part of the paleontology-focused Woranso-Mille Project that has been ongoing in the region since 2004.
The researchers report the finding in this week's Proceedings of the National Academy of Sciences early online publication. The National Science Foundation is a major funder of the work.
Previous examinations of Lucy, who lived 3.2 million years ago, led some scientists to conclude A. afarensis was not fully adapted to upright walking. The newly recovered fossil, nicknamed "Kadanuumuu" and pronounced "kah-DAH-noo-moo," clears up the debate.
"Kadanuumuu" appears to be in good agreement with fossilized footprints dated to about 3.6 million years ago and discovered in Laetoli, a site in Tanzania in eastern Africa. The footprints show that early human ancestors habitually walked upright; there are no knuckle-impressions or signs of abducted toes.
The misinterpretation concerning Lucy's ability to walk upright resulted largely from her small frame, said Haile-Selassie referring to her estimated 3 1⁄2 feet. But "Kadanuumuu," whose name means "big man" in the Afar language, is 5 to 5 1/2 feet tall and the proportion of the length of his legs to his arms compares favorably to modern humans.
Long legs are a tell-tale human characteristic of bipedalism. "Generally speaking, the skeleton clearly shows that the emergence of advanced bipedality is not associated with the first appearance of our genus Homo," said Haile-Selassie. "But rather it has deep roots going back to more than 3.6 million years ago."
"Kadanuumuu" also has most of the same skeletal parts as Lucy and others never previously known, including a significant portion of the rib cage and a nearly complete adult shoulder blade.
"'Kadanuumuu's' shoulder was also a major discovery," said Haile-Selassie. "It shows that our ancestor's shoulder blade and rib cage were much more similar to those of modern humans than previously had been thought."
Before now anthropologists concluded evolutionary ancestors had shoulders more like those of chimpanzees. But "Kadanuumuu" surprised researchers by revealing a shoulder very different from chimpanzees, which are thought to be the closest living relatives of Homo sapiens.
"This tells us that chimpanzees have evolved a great deal since we shared a last common ancestor with them," said Haile-Selassie.
Renowned Ethiopian fossil hunter Alemayehu Asfaw found the first element of "Kadanuumuu" in February 2005 at Korsi Dora, about 210 air miles northeast of the Ethiopian capital Addis Ababa.
The specimen was exposed on the surface and further investigation resulted in the recovery of more elements. Excavations between 2005 and 2008 uncovered an upper arm, a collarbone, neck bones, ribs, pelvis, sacrum, a thighbone, a shinbone and the shoulder blade. Excavations took more than five years to complete.
Publication of more results will continue as researchers complete more detailed analysis of Kadanuumuu. Scientists from Case Western Reserve University, Ohio; Berkeley Geochronology Center, Calif.; Addis Ababa University, Ethiopia; and Kent State University, Ohio contributed to this research.
(Photo: Yohannes Haile-Selassie, Cleveland Museum of Natural History)
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