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Wednesday, August 31, 2011

Giant Undersea Farms Planned, Will Yield 2 Billion Liters Of Kelp Fuel Each A Year

An underwater “field” as big as a Norwegian county could provide two billion litres of kelp-based fuel a year. SINTEF is currently establishing a centre of expertise that will enable us to cultivate seaweed and kelp on a large scale.

Trine Galloway at SINTEF thinks that seaweed and kelp have great potential for industrial applications.
Photo: Thor Nielsen.

Kelp cultivation will mean that we can produce bioethanol fuel in addition to biogas for heating and fuel, without the need to use food crops as a raw material, and without having to utilise agricultural land or freshwater resources.

This is among the reasons behind SINTEF’s decision to establish the Norwegian Centre for Seaweed and Kelp Technology, which was opened in Trondheim on August 15 by State Secretary Kristine Gramstad of the Ministry of Fisheries and Coastal Affairs

Many areas of application

There are even more potential uses of kelp and seaweed beyond applications as sources of energy.

As well as being an energy resource, macroalgae such as kelp and seaweed are used in food production and as agents that bind water, in biological purification systems, the reestablishment of kelp cultures in fjords that have suffered high rates of kelp mortality, as soil improvers and in the hunt for new compounds for medical and industrial applications (bioprospecting).

Exciting interface

“Macroalgae cultivation lies at an exciting interface between better resource utilisation, new marine-based products and potential renewable energy production. Although the process of establishing new industry can be demanding, I believe that a maritime land such as Norway, with its major offshore and marine supply industries, solid research base and a world-beating aquaculture industry should be quite capable of achieving success in this field,” says State Secretary Gramstad.

Efficiency challenges

Today, some 15 million tonnes of seaweed and kelp are cultivated all over the world, mostly in Asia, and are used in foods, animal feedstuffs, chemicals, medicines, health foods, cosmetics and fertilisers.

“The Norwegian coastline, including all its islands, is twice as long as the Equator. In other words, we possess huge areas that are suitable for cultivating seaweed and kelp. However, manpower is more expensive here than in Asia. This means that the greatest challenge lies in cultivating large volumes at sufficiently low cost, and research-based knowledge will be essentlal if we are to manage this,”says chief scientist Trina Galloway of SINTEF Fisheries and Aquaculture.

International invitations

Galloway says that SINTEF has already been cultivating kelp on a trial basis, on behalf of Norwegian industrial interests and with financial support from the the Research Council of Norway.

“We ourselves have a good deal of competence, but there are also inportant sources of knowledge elsewhere in the world. The aim of the centre is to gather all such sources of expertise into a single team, so we are inviting both Norwegian and overseas research gropups into the centre.

Could be fertilised by farmed fish

The competence centre will offer industry and the authorities its knowledge, which will cover everything from controlled production of seed plants and cultivation in the sea to harvesting and processing the raw material for a wide range of applications.

Seaweed and kelp take up nutrient salts (fertilisers) and CO2 from the sea. The plants can be cultivated in dedicated macroalgae systems, or side by side with farmed fish. The plants can thus be fertilised by the fish and thus help to cleanse the water around the sea-cages.

From harvesting to cultivation

At present, seaweed and kelp are not cultivated commercially in Norway. But we already have a major industry based on an annual harvest of around 150,000 tonnes of kelp from which alginates are extracted. These are substances that have the ability to thicken and stabilise liquids, and are therefore used in a large number of food products. Grisetang is also used to produce kelp meal, which is used as a soil improver and in animal feed and health-food products.

“Although harvesting removes less than one percent of Norway’s standing seaweed and kelp biomass, we do not recommend taking out more than this amount, as kelp forests are actually important nursery and feeding grounds for a wide range of invertebrates and fish. If we want to expand our kelp-based industry, we will have to cultivate kelp on a large scale,” says Galloway.

Contacts and sources:

'Gene Overdose' Causes Extreme Thinness

Scientists have discovered a genetic cause of extreme thinness for the first time, in a study published today in the journal Nature.

The research shows that people with extra copies of certain genes are much more likely to be very skinny. In one in 2000 people, part of chromosome 16 is duplicated, making men 23 times and women five times more likely to be underweight.

Each person normally has a copy of each chromosome from each parent, so we have two copies of each gene. But sometimes sections of a chromosome can be duplicated or deleted, resulting in an abnormal 'dosage' of genes.

In a study examining the DNA of over 95,000 people, researchers at Imperial College London and the University of Lausanne have identified that duplication of a part of chromosome 16 is associated with being underweight, defined as a a body mass index below 18.5. Half of all children with the duplication in the study have been diagnosed with a 'failure to thrive', meaning that their rate of weight gain is significantly lower than normal. A quarter of people with the duplication have microcephaly, a condition in which the head and brain are abnormally small, which is associated with neurological defects and shorter life expectancy. Last year, the same researchers discovered that people with a missing copy of these genes are 43 times more likely to be morbidly obese.

Professor Philippe Froguel, from the School of Public Health at Imperial College London, who led the study, said: "The dogma is that we have two copies of each gene, but this isn't really true. The genome is full of holes where genes are lost, and in other places we have extra copies of genes. In many cases, duplications and deletions have no effect, but occasionally they can lead to disease.

"So far, we have discovered a large number of genetic changes that lead to obesity. It seems that we have plenty of systems that increase appetite since eating is so important – you can suppress one and nothing happens. This is the first genetic cause of extreme thinness that has been identified.

"One reason this is important is that it shows that failure to thrive in childhood can be genetically driven. If a child is not eating, it's not necessarily the parents' fault.

"It's also the first example of a deletion and a duplication of one part of the genome having opposite effects. At the moment we don't know anything about the genes in this region. If we can work out why gene duplication in this region causes thinness, it might throw up new potential treatments for obesity and appetite disorders. We now plan to sequence these genes and find out what they do, so we can get an idea of which ones are involved in regulating appetite."

The part of chromosome 16 identified in the study contains 28 genes. Duplications in this region have previously been linked with schizophrenia, and deletions with autism.

Contacts and sources:
Sam Wong
Imperial College London

How White Blood Cell Promotes Growth And Spread Of Cancer Revealed

Scientists at The Scripps Research Institute have shown that a particular white blood cell plays a direct role in the development and spread of cancerous tumors. Their work sheds new light on the development of the disease and points toward novel strategies for treating early-stage cancers.

The study was published in September 2011 print issue of the American Journal of Pathology.

Scripps Research Professor James Quigley, Staff Scientist Elena Deryugina, and colleagues had previously demonstrated that white blood cells known as neutrophils—bone marrow-derived cells that function as “first responders” at sites of acute inflammation—promote the growth of new blood vessels in normal, healthy tissue.

The team has now tied these cells to the induction and growth of new blood vessels in malignant tumors and to the spread of tumor cells through those newly formed vessels. The scientists have also uncovered some of the mechanisms underpinning this process—which could be interrupted by properly targeted drugs.

Potent and Uninhibited

The Scripps Research team has been particularly interested in neutrophils, in part because several studies have demonstrated a link between elevated neutrophil levels and high rates of tumor invasion among cancer patients. Mounting evidence has also indicated that neutrophils play a particularly important role during the early stages of tumor development.

“During tumor development, neutrophils appear to be one of the first inflammatory cell types on the scene,” said Deryugina, who spearheaded the new study.

The researchers have been especially interested in the blood vessel-forming or “angiogenic,” powers of neutrophils, which stem from a special enzyme they produce known as MMP-9 (matrix metalloproteinase type 9). The enzyme is, in fact, synthesized by a number of different types of white blood cells and has long been linked to tumor development. But the particular form synthesized by neutrophils is especially potent, in part because it does not come bound up with the natural inhibitory regulating agents that other cells supply.

Whereas other types of white blood cells only manufacture the enzyme later and invariably deliver it in combination with one of its natural inhibitors, neutrophils come loaded with pre-synthesized MMP-9 in a form that is unencumbered.

Making the Case

In a series of cleverly designed experiments, Quigley, Deryugina, and colleagues established a link between neutrophils, their MMP-9, and the growth and spread of tumors.

The scientists alternately raised and lowered the quantity of neutrophils allowed to flow into two different kinds of early-stage tumors, which had been transplanted into chicken embryos and mice. They also introduced several different versions of the enzyme, sometimes combining it with dampening agents, sometimes not.

By observing the subsequent decrease and increase in the formation of new blood vessels, the Scripps Research team was able to establish that the unique form of the enzyme delivered by neutrophils was directly responsible for heightening the growth of new blood vessels in the tumors. Just as importantly, they were able to determine that the newly formed blood vessels served as “escape routes” or conduits for the spread of tumor cells beyond their initial location.

First, the scientists established that the most aggressive tumors—that is, the ones that were able to most quickly penetrate the surrounding blood vessels and spread to different areas—depended on their ability to attract large numbers of neutrophils.

The researchers then proceeded to spur the growth of new blood vessels in even relatively nonaggressive tumors by supplying additional quantities of neutrophil-derived enzyme. They also blocked the formation of new vessels with the anti-inflammatory drug ibuprofen and then restored, or “rescued,” angiogenesis by pumping in additional enzyme.

Quigley and Deryugina also drastically reduced the influx of neutrophils by neutralizing IL-8 (interleukin 8), the chemical attractant that draws neutrophils to sites of inflammation. Blood vessel formation declined correspondingly, as did the penetration of vessels by tumor cells, clearly linking neutrophils to the development and spread of two different, but highly aggressive, forms of cancer. To further strengthen that link, the researchers again reversed the decline with an infusion of neutrophil-derived enzyme.

“By dampening neutrophil influx into tumors, we dampen angiogenesis, but we also dampen metastasis,” Quigley said. “And when we rescue angiogenesis, we also rescue the high metastatic rate of the tumors.”

Significantly, only the unregulated, uninhibited version of the enzyme provided by neutrophils reversed the dampening effect caused by reducing inflammation or cutting off the flow of neutrophils. No such rescue occurred when the enzyme was combined with its natural inhibiting agents—the same molecules that accompany the enzyme when it is delivered by other kinds of white blood cells.

Intriguing Possibilities

The scientists note that the study suggests tumors that engender a strong inflammatory response may be particularly amenable to early-stage treatment by drugs that specifically target neutrophils, whether that means inhibiting the enzyme they deliver or simply preventing them from showing up in the first place.

“It might be best to combat tumor angiogenesis earlier rather than later,” Quigley said, adding that “more specifically directed anti-neutrophil agents might be better suited than a general anti-inflammatory.”

The Quigley lab continues to investigate.

In addition to Quigley and Deryugina, authors of this paper, “Neutrophil MMP-9 in Tumor Progression” (doi:10.1016/j.ajpath.2011.05.031), include Bernhard Schweighofer, Tatyana A. Kupriyanova, Ewa Zajac, Veronica C. Ardi, all of Scripps Research; and Erin M. Bekes, formerly a UCSD graduate student doing her thesis at Scripps Research and now a postdoctoral fellow at the NYU School of Medicine. Seehttp://www.sciencedirect.com/science/article/pii/S000294401100530X

Support for this study came from the National Institutes of Health, Scripps Translational Science Institute, the Max Kade Foundation, and the National Cancer Institute.

About The Scripps Research Institute

The Scripps Research Institute is one of the world's largest independent, non-profit biomedical research organizations. Scripps Research is internationally recognized for its discoveries in immunology, molecular and cellular biology, chemistry, neuroscience, and vaccine development, as well as for its insights into autoimmune, cardiovascular, and infectious disease. Headquartered in La Jolla, California, the institute also includes a campus in Jupiter, Florida, where scientists focus on drug discovery and technology development in addition to basic biomedical science. Scripps Research currently employs about 3,000 scientists, staff, postdoctoral fellows, and graduate students on its two campuses. The institute's graduate program, which awards Ph.D. degrees in biology and chemistry, is ranked among the top ten such programs in the nation. For more information, see www.scripps.edu.
Contacts and sources:
Mika Ono
Scripps Research Institute

Trust In Your Neighbors Could Benefit Your Health, MU Study Shows

Here’s an easy way to improve your health: trust your neighbors. A new study from the University of Missouri shows that increasing trust in neighbors is associated with better self-reported health.

Eileen Bjornstrom, an assistant professor of sociology in the MU College of Arts and Science, found that people reported better health when they trusted their neighbors.
Credit MU

“I examined the idea of ‘relative position,’ or where one fits into the income distribution in their local community, as it applies to both trust of neighbors and self-rated health,” said Eileen Bjornstrom, an assistant professor of sociology in the MU College of Arts and Science. 

 “Because human beings engage in interpersonal comparisons in order to gauge individual characteristics, it has been suggested that a low relative position, or feeling that you are below another person financially, leads to stress and negative emotions such as shame, hostility and distrust, and that health suffers as a consequence. While most people aren’t aware of how trust impacts them, results indicated that trust was a factor in a person’s overall health.”

In the study, Bjornstrom examined the 2001 Los Angeles Family and Neighborhood Survey. Contrary to expectations, she found that respondents with a higher income, relative to their community, were more likely to be distrustful of their neighbors. Simultaneously, while taking into account factors such as level of education, income, and age, people who reported that “their neighbors can be trusted” also reported better health on average.

“I was surprised about the direction in which relative position was linked to distrust. If affluent individuals are less likely to trust their poorer neighbors, it could be beneficial to attempt to overcome some of the distrust that leads to poor health,” Bjornstrom said. “It is possible that shared community resources that promote interaction, such as sidewalks and parks, could help bridge the neighborhood trust gap, and also promote health and well-being. Residents of all economic statuses might then benefit if community cohesion was increased. Additional research can address those questions.”

While there was not a direct link between low relative position among neighbors and better health, Bjornstrom believes that further study needs to occur in different contexts. She believes that research on relative position in the workplace or among social networks would provide greater insight.

“For example, relative position at work could matter for health because it might be associated with autonomy or other benefits,” Bjornstrom said.

Bjornstrom’s study, “The Neighborhood Context of Relative Position, Trust and Self-Rated Health,” appears in the journal Social Science & Medicine.
Contacts and sources:
Steven Adams
University of Missouri-Columbia

Nevada Wallops Bank of America With Sweeping Suit; Nationwide Foreclosure Settlement in Peril

by Paul KielProPublica

The state of Nevada dramatically expanded its lawsuit against Bank of America today, turning the narrow case it filed late last year into a broadside that targets virtually all aspects of the bank's mortgage operations. Bank of America has previously denied wrongdoing.

The sweeping new suitcould have repercussions far beyond Nevada's borders. It further jeopardizes a possible nationwide settlement with the five largest U.S. banks over their foreclosure practices, especially given concerns voiced by other attorneys general, New York's foremost among them. (You can read the suit here.)

In a statement, Bank of America spokeswoman Jumana Bauwens said reaching a settlement would bring a better outcome for homeowners than litigation. "We believe that the best way to get the housing market going again in every state is a global settlement that addresses these issues fairly, comprehensively and with finality."

The suit also weakens a separate, 2008 multistate settlement in which Countrywide promised to evaluate troubled homeowners for loan modifications.

Most broadly, Nevada's action signals that the banks' problems with home mortgages—the main cause of the financial crisis—continue to burden them and rattle investors. Bank of America, the nation's largest bank and company that services mortgages, has seen its stock plunge about 40 percent since March, in part because of its mortgage liabilities. Nevada's action won't help.

Nevada's attorney general charges that Bank of America and the now-defunct mortgage giant Countrywide acquired by the bank in 2008, deceived borrowers and investors at almost every stage of the process.

According to the suit, borrowers were duped into unaffordable loans and then victimized again through a misleading mortgage modification program that homeowners tried to use to avoid foreclosure. Finally, the suit alleges, the bank filed fraudulent documents to move forward with the foreclosures.

"Taken together and separately, [Bank of America's] deceptive practices have resulted in an explosion of delinquencies and unauthorized and unnecessary foreclosures in the state of Nevada," the suit alleges.

The state's suit had previously been confined to the modification issue. At that time, Bank of America also said homeowners would be best served not through litigation but through reaching a multistate settlement that would "broaden programs for homeowners who need assistance."

By expanding the suit, Nevada's Catherine Cortez Masto joins New York Attorney General Eric Schneiderman in stepping up investigations of the bank. In addition to initiating a broad investigation of banks' securitization practices, he recently filed a suit charging that Bank of America had fraudulently foreclosed on homeowners.

A coalition of all 50 state attorneys general has been seeking a settlement with the five largest banks to address their foreclosure practices, such as the filing of thousands of false sworn statements with state courts. Some critics have said the states were speeding to an agreement without thoroughly investigating the banks' abuses.

Last week, fissures in the coalition became public when Iowa Attorney General Tom Miller, who leads the 50-state coalition, removed New York's Schneiderman from the group's executive committee because, he said, Schneiderman had "actively worked to undermine" its efforts by opposing any quick settlement. As part of any settlement (reportedly in the range of $20 billion to $25 billion), the banks have been seeking a wide-ranging release from future legal claims, not just those related to foreclosure practices. Schneiderman has publicly rejected that idea and pushed ahead with his investigation.

Masto's suit signals that Nevada may also reject any settlement in the near future on the foreclosure issues. Two other attorneys general, notably those from Massachusetts andDelaware, have also voiced concerns recently about any broad waiver of claims.

Geoff Greenwood, the spokesman for Iowa's attorney general, declined to comment on Nevada's suit.

Nevada's newly expanded suit also undermines a previous settlement between Countrywide and numerous attorneys general. In 2008, as part of that settlement, Bank of America agreed to implement a mortgage modification program to address charges that Countrywide's marketing and lending practices had defrauded borrowers. That promised wave of modifications never came, however, so Nevada alleges Bank of America has breached the agreement. The expanded suit revives those allegations.

In its new claims, Nevada also charges that Countrywide bungled the process of bundling loans into securities by not properly documenting the transfer of assets. Despite the lack of documentation, Bank of America has fraudulently pursued foreclosure on these homes anyway, the suit charges.

New York's Schneiderman made similar charges earlier this month when he sued Bank of New York Mellon, which, as trustee for several pools of Countrywide loans, was supposed to oversee the securities for investors. Countrywide's failure to transfer complete mortgage loan documentation "impair[ed] the value of the notes secured by those mortgages" and "triggered widespread fraud, including Bank of America's fabrication of missing documentation," the suit charges.

Contacts and sources:
Story by Paul Kiel

Like Mama Bears, Nursing Mothers Defend Babies With A Vengeance

Women who breast-feed are far more likely to demonstrate a "mama bear" effect — aggressively protecting their infants and themselves — than women who bottle-feed their babies or non-mothers, according to a new study in the September issue of Psychological Science, a journal of the Association for Psychological Science.

Bear Cub
File:Bear cub.jpg
And when breast-feeding women behave aggressively, they register a lower blood pressure than other women, the study found. The results, the researchers say, suggest that breast-feeding can help dampen the body's typical stress response to fear, giving women the extra courage they need to defend themselves.

"Breast-feeding has many benefits for a baby's health and immunity, but it seems to also have a little-known benefit for the mother," said Jennifer Hahn-Holbrook, a postdoctoral fellow in the UCLA Department of Psychology and the study's lead author. "It may be providing mothers with a buffer against the many stressors new moms face while at the same time, giving mothers an extra burst of courage if they need to defend themselves or their child."

But the aggression demonstrated by breast-feeding mothers has its limits, Hahn-Holbrook added.

"Breast-feeding mothers aren't going to go out and get into bar fights, but if someone is threatening them or their infant, our research suggests they may be more likely to defend themselves in an aggressive manner," she said.

The breast-feeding mothers' reaction is known as "lactation aggression" or "maternal defense" in mammals.

Hahn-Holbrook was aware that non-human female mammals, including macaques, rats, mice, hamsters, lions, deer, sheep and others, display more aggression when they are lactating than at any other reproductive stage, but she couldn't find any research that tested that reaction in people. So she decided to set up the first experiment to study lactation aggression in humans.

For the study, researchers recruited three groups of women — 18 nursing mothers, 17 women who were feeding formula to their babies and 20 non-mothers. Each woman was asked to compete in a series of computerized time-reaction tasks against a research assistant posing as an overtly rude study participant. The women's infants were supervised in an adjoining room.

Upon winning a round in the competition, the victor was allowed to press a button and deliver a loud and lengthy "sound blast" to the loser — an act of aggressiveness. The researchers found that breast-feeding mothers delivered sound blasts to the rude research assistant that were more than twice as loud and long as those administered by non-mothers and nearly twice as loud and long as those by bottle-feeding mothers. This was true both before and after the breast-feeding mothers nursed their infants.

The researchers also measured participants' stress levels via blood pressure during the experiment. Breast-feeding mothers' systolic blood pressure was found to be approximately 10 points lower than women who were feeding formula to their infants and 12 points lower than non-mothers.

Previous research in non-human mammals has shown that lactation enables heightened defensive aggression by down-regulating the body's response to fear, a phenomenon that benefits the survival of both mothers and their offspring. The lower blood pressure seen in the breast-feeding mothers during acts of aggression, the researchers say, is an indication that the same mechanism is likely at work in humans as well.

Contacts and sources:

40-Year Follow-Up On Marshmallow Test Points To Biological Basis For Delayed Gratification

A landmark study in the late 1960s and early 1970s used marshmallows and cookies to assess the ability of preschool children to delay gratification. If they held off on the temptation to eat a treat, they were rewarded with more treats later. Some of the children resisted, others didn't.

Colored marshmallows
Image: Wikipedia

A newly published follow-up revisits some of the same children, now adults, revealing that these differences remain: Those better at delaying gratification as children remained so as adults; likewise, those who wanted their cookie right away as children were more likely to seek instant gratification as adults. Furthermore, brain imaging showed key differences between the two groups in two areas: the prefrontal cortex and the ventral striatum. The findings are published in the Aug. 29 edition of the Proceedings of the National Academy of Sciences.

"This is the first time we have located the specific brain areas related to delayed gratification. This could have major implications in the treatment of obesity and addictions," says lead author Dr. B.J. Casey, director of the Sackler Institute for Developmental Psychobiology at Weill Cornell Medical College and the Sackler Professor of Developmental Psychobiology.

In the current study, Dr. Casey and her co-investigators recruited 59 adults who participated as young children in the original study and represented either extreme of the delayed-gratification spectrum -- high delayers and low delayers. Because marshmallows and cookies can be less rewarding to adults, the researchers substituted two tests. 

In the first, participants looked at a screen displaying a series of faces and were asked to signal only when a face of one gender was shown. This "cool" test revealed no significant differences between the two groups. A second, "hot" test used emotional cues such as a happy or frightened face. These results were much more varied and revealed that aptitude for delayed gratification was consistent from childhood into adulthood.

"In this test, a happy face took the place of the marshmallow. The positive social cue interfered with the low delayer's ability to suppress his or her actions," explains Dr. Casey.

The second test was then repeated while the participant's brain was scanned using functional magnetic resonance imaging (fMRI). The results showed that the brain's prefrontal cortex was more active for high delayers and the ventral striatum -- an area linked to addictions -- was more active in low delayers.

The original marshmallows and cookies study was led by Dr. Walter Mischel, a co-author of the current study and the Niven Professor of Humane Letters at Columbia University.

Contacts and sources:
Takla Boujaoude
New York- Presbyterian Hospital/Weill Cornell Medical Center/Weill Cornell Medical College

Additional authors include Leah H. Somerville, Theresa Teslovich and Nicholas Franklin of Weill Cornell Medical College; Vivian Zayas of Cornell University, Ithaca, N.Y.; Gary Glover and Ian H. Gotlib of Stanford University; Ozlem Ayduk of the University of California, Berkeley; Mary Askren, John Jonides and Marc G. Berman of the University of Michigan, Ann Arbor; and Yuichi Shoda and Nicole L. Wilson of the University of Washington, Seattle. Funding for this multi-site study was provided by the National Institutes of Health (PI: Yuichi Shoda).

The Sackler Institute at Weill Cornell Medical College

The Sackler Institute for Developmental Psychobiology at Weill Cornell Medical College, established and endowed in 1996 by The Sackler Foundation–La Fondation Sackler and certain Mortimer D. Sackler family members and related entities, is focused on research and training using the techniques of brain imaging, human genetics, electrophysiology and behavioral methods to study typical and atypical human brain development. The Sackler Institute at Weill Cornell is one of six Sackler Institutes, programs and centers; others include Columbia University Medical Center; Universities of Edinburgh and Glasgow; University of Sussex; and McGill University.

Weill Cornell Medical College

Weill Cornell Medical College, Cornell University's medical school located in New York City, is committed to excellence in research, teaching, patient care and the advancement of the art and science of medicine, locally, nationally and globally. 

Physicians and scientists of Weill Cornell Medical College are engaged in cutting-edge research from bench to bedside, aimed at unlocking mysteries of the human body in health and sickness and toward developing new treatments and prevention strategies. In its commitment to global health and education, Weill Cornell has a strong presence in places such as Qatar, Tanzania, Haiti, Brazil, Austria and Turkey. Through the historic Weill Cornell Medical College in Qatar, the Medical College is the first in the U.S. to offer its M.D. degree overseas. Weill Cornell is the birthplace of many medical advances -- including the development of the Pap test for cervical cancer, the synthesis of penicillin, the first successful embryo-biopsy pregnancy and birth in the U.S., the first clinical trial of gene therapy for Parkinson's disease, and most recently, the world's first successful use of deep brain stimulation to treat a minimally conscious brain-injured patient. 

Weill Cornell Medical College is affiliated with NewYork-Presbyterian Hospital, where its faculty provides comprehensive patient care at NewYork-Presbyterian Hospital/Weill Cornell Medical Center. The Medical College is also affiliated with the Methodist Hospital in Houston. For more information, visit weill.cornell.edu.

UF Medicinal Chemists Modify Sea Bacteria Byproduct For Use As Potential Cancer Drug

University of Florida researchers have modified a toxic chemical produced by tiny marine microbes and successfully deployed it against laboratory models of colon cancer.

Writing today in ACS Medicinal Chemistry Letters, UF medicinal chemists describe how they took a generally lethal byproduct of marine cyanobacteria and made it more specifically toxic — to cancer cells.

When the scientists gave low doses of the compound to mice with a form of colon cancer, they found that it inhibited tumor growth without the overall poisonous effect of the natural product. Even at relatively high doses, the agent was effective and safe.

“Sometimes nature needs a helping human hand to further optimize these products of evolution to treat human diseases,” said Hendrik Luesch, an associate professor of medicinal chemistry at UF’s College of Pharmacy. “Based on what we learned about apratoxins’ mechanism of action, we knew this compound class had great potential for use in anticancer therapies; however, the natural product itself is too toxic to become a therapeutic.”

The researchers synthesized several apratoxin compounds that were similar to the original except for slight differences in composition, designing one that proved to be extremely potent against the cancer cells in cultures and in mice, but without the overwhelming toxicity.

The compound acts as a single agent to reduce levels of two types of proteins that are targeted by cancer research labs around the world — growth factors, and enzymes called tyrosine kinases, which act as receptors for the growth factors.

Known as apratoxin S4, the compound strips colon cancer cells of their ability to both secrete and use naturally occurring factors that fuel growth — something that Luesch, postdoctoral chemist Oi-Yen Chen, and assistant scientist Yanxia Liu, say is a powerful “one-two punch” against mushrooming populations of cancer cells.

The trio describes apratoxin’s dual action for the first time in today’s online publication, although Luesch presented early findings in May at the New York Academy of Sciences.

“This is an extremely interesting discovery that may have the potential to lead to a novel drug, but an extraordinary amount of additional research is needed before we will know. We can hope,” said David J. Newman, chief of the National Cancer Institute’s Natural Products Branch, who was not involved in the research. “Luesch has found a novel compound and a novel mechanism of action that stops the secretion of the receptor and the growth factor — as far as I am aware, this mechanism has only been shown in apratoxin at this time. If nothing else, he has shown us a new way to kill tumor cells and has revealed a new chemistry, and those are important steps.”

Apratoxin is produced by cyanobacteria, microbes that have evolved toxins to fend off predators and cope with harsh conditions in a marine environment. Collectively known as blue-green algae — a misnomer because the single-celled organisms are not algae or members of the plant kingdom — a wide variety of cyanobacteria species exists in both sea and freshwater environments.

Like plants, cyanobacteria convert sunlight into energy through a process known as photosynthesis. But where plants exclusively use a green pigment called chlorophyll to capture light to make food, cyanobacteria also use a bluish pigment called phycocyanin.

In addition, cyanobacteria have the unique ability to use respiration as well as photosynthesis to acquire energy, making these organisms tiny chemical factories capable of producing many as-yet unidentified molecules that may be useful for health applications.

“Marine cyanobacteria produce a huge diversity of compounds,” said Luesch, who is also a member of the UF Shands Cancer Center. “About half of anticancer drugs are based on natural products. All but a couple of them are derived from terrestrial organisms, yet more than 70 percent of the Earth is covered by oceans, which presumably contain a number of therapeutic molecules with potentially novel biological activities. When we studied the biological effects of apratoxin, we predicted it would be particularly useful against colon cancer if we could engineer it to be more selective.”

Chen synthesized the apratoxins, while Liu carried out the biology and pharmacology experiments. More lab work is required before a drug based on apratoxin can be tested in patients with colon cancer, but Luesch believes apratoxin S4 is the first candidate to show the needed tumor selectivity, antitumor effects and potency to be effective. The UF Research Opportunity Fund and the Bankhead-Coley Cancer Research Program supported the study.

Contacts and sources:
John Pastor
University of Florida

Manufacturing Method Paves Way For Commercially Viable Quantum Dot-Based Leds

University of Florida researchers may help resolve the public debate over America's future light source of choice: Edison's incandescent bulb or the more energy efficient compact fluorescent lamp.

It could be neither.

Instead, America's future lighting needs may be supplied by a new breed of light emitting diode, or LED, that conjures light from the invisible world of quantum dots. According to an article in the current online issue of the journal Nature Photonics, moving a QD LED from the lab to market is a step closer to reality thanks to a new manufacturing process pioneered by two research teams in UF's department of materials science and engineering.

"Our work paves the way to manufacture efficient and stable quantum dot-based LEDs with really low cost, which is very important if we want to see wide-spread commercial use of these LEDs in large-area, full-color flat-panel displays or as solid-state lighting sources to replace the existing incandescent and fluorescent lights," said Jiangeng Xue, the research leader and an associate professor of material science and engineering "Manufacturing costs will be significantly reduced for these solution-processed devices, compared to the conventional way of making semiconductor LED devices."

A significant part of the research carried out by Xue's team focused on improving existing organic LEDs. These semiconductors are multilayered structures made up of paper thin organic materials, such as polymer plastics, used to light up display systems in computer monitors, television screens, as well as smaller devices such as MP3 players, mobile phones, watches, and other handheld electronic devices. OLEDs are also becoming more popular with manufacturers because they use less power and generate crisper, brighter images than those produced by conventional LCDs (liquid crystal displays). Ultra-thin OLED panels are also used as replacements for traditional light bulbs and may be the next big thing in 3-D imaging.

Complementing Xue's team is another headed by Paul Holloway, distinguished professor of materials science and engineering at UF, which delved into quantum dots, or QDs. These nano-particles are tiny crystals just a few nanometers (billionths of a meter) wide, comprised of a combination of sulfur, zinc, selenium and cadmium atoms. When excited by electricity, QDs emit an array of colored light. The individual colors vary depending on the size of the dots. Tuning, or "adjusting," the colors is achieved by controlling the size of the QDs during the synthetic process.

By integrating the work of both teams, researchers created a high-performance hybrid LED, comprised of both organic and QD-based layers. Until recently, however, engineers at UF and elsewhere have been vexed by a manufacturing problem that hindered commercial development. An industrial process known as vacuum deposition is the common way to put the necessary organic molecules in place to carry electricity into the QDs. However, a different manufacturing process called spin-coating, is used to create a very thin layer of QDs. Having to use two separate processes slows down production and drives up manufacturing costs.

According to the Nature Photonics article, UF researchers overcame this obstacle with a patented device structure that allows for depositing all the particles and molecules needed onto the LED entirely with spin-coating. Such a device structure also yields significantly improved device efficiency and lifetime compared to previously reported QD-based LED devices.

Spin-coating may not be the final manufacturing solution, however.

"In terms of actual product manufacturing, there are many other high through-put, continuous "roll-to-roll" printing or coating processes that we could use to fabricate large area displays or lighting devices," Xue said. "That will remain as a future research and development topic for the university and a start-up company, NanoPhotonica, that has licensed the technology and is in the midst of a technology development program to capitalize on the manufacturing breakthrough."
Contacts and sources:
Jiangeng Xue
University of Florida

Penn Physicists Develop New Insight Into How Disordered Solids Deform

In solid materials with regular atomic structures, figuring out weak points where the material will break under stress is relatively easy. But for disordered solids, like glass or sand, their disordered nature makes such predictions much more daunting tasks.

Now, a collaboration combining a theoretical model with a first-of-its kind experiment has demonstrated a novel method for identifying “soft spots” in such materials. The findings from University of Pennsylvania and Syracuse University physicists may lead to better understanding of the principles that govern materials responses ranging from failure of glasses to earthquakes and avalanches.

The experimental research was conducted by professors Arjun G. Yodh and Andrea J. Liu, along with post-doctoral associates Ke Chen, Wouter G. Ellenbroek and Zexin Zhang and graduate student Peter J. Yunker, all of the Department of Physics and Astronomy in Penn’s School of Arts and Sciences. They collaborated with Lisa Manning of the Department of Physics at Syracuse. Liu and Manning described the theoretical model in a separate study.

Both studies appear in the journal Physical Review Letters.

For materials with well ordered, crystalline internal structures, such as diamonds or most metals, identifying soft spots is easy; weak, disordered sections stick out like a sore thumb.

“In perfect crystalline materials, atoms are in well-defined positions. If you give me the position of one atom, I can tell you the position of another with precision,” Yodh said. “There’s also a well defined theory about what’s happening with defects in crystals when stresses are applied to them.”

“There’s no periodicity in glass, however,” Chen said. “You can’t look at it and say, ‘This part looks different than the rest,’ because there is no background pattern to compare it with.”

With physical structure a dead end for identifying soft spots, the physicists turned to another property: vibrations. Though the word “solid” is synonymous with “unmoving,” the particles that make up solid matter are constantly vibrating. And like the different tones of guitar strings, there are many different ways particles in a solid can vibrate. These are known as “vibration modes.”

For crystalline materials, the regular patterns of atoms lead to uniform patterns of vibrations within the material; nearly all particles are involved in a typical vibration. In disordered materials, with their unevenly spaced particles, particles in different regions vibrate differently, producing some new and different vibration modes, particularly at low frequencies.

“We can determine the spatial patterns of the different vibrations in our experiment, and then we can find out whether some of them, particularly low frequency vibrations, are connected with rearrangements or failure of the material when it is stressed,” Chen said.

Manning and Liu developed a simulation to test this kind of correlation under idealized conditions. They were able to show that certain regions highlighted by low frequency vibration modes acted like defects in disorganized materials and that these defects were good candidates for where the material would fail when stressed.

“We showed, for the first time, a correlation between the soft spot population and rearrangements under stress,” Manning said. “This is something people have been looking for over the past 30 or 40 years.”

Though the success of the simulation was an exciting result by itself, it was only a first step. Real-world systems have additional layers of complexity, notably temperature and related thermal fluctuations that can rapidly change the interactions between neighboring particles and thus the system’s vibrational patterns.

“It was not at all obvious that the soft spots we found in the simulation would still exist in the presence of thermal fluctuations, which are unavoidable in the real world,” Liu said. “Thermal fluctuations, for example, might have caused the soft spots to be wiped out too rapidly to be used for analysis.”

To see if this was the case, Chen developed an experimental system with many features similar to the one in the simulation. At its core was a colloidal glass, an effectively two-dimensional material consisting of a single disordered layer of soft plastic particles tightly packed together.

By analyzing video of the particles’ motion in the colloidal glass as observed under a microscope, Chen was able to calculate the vibration patterns and then use Manning and Liu’s model to locate regions vulnerable to rearrangement once the glass was put under stress. He then compared these regions to the rearrangements that actually happened.

Just as in the simulation, the soft spots predicted candidates for rearrangement, as some of the identified soft spots remained intact while others deformed. The experiment thus provides a new basis — low frequency vibration modes — for analyzing real-world disordered solids.

“Low frequency vibrations correspond to areas with weak interaction between particles, and because of these weak interactions their structure is less stable. When they’re perturbed there is less resistance from their neighbors.” Chen said.

Disordered solids are much more common than ordered ones, so having a working theory of how, why and where they break has many potential applications.

“You can bend a metal spoon, but you can’t bend one made out of glass without breaking it. If you can understand how disordered solids fail, you might be able to make them tougher,” Yodh said.

The research was funded by the National Science Foundation, including the Penn Materials Research Science and Engineering Center, the Princeton Center for Theoretical Science at Princeton University, NASA and the U.S. Department of Energy.

Zexin Zhang has appointments with the CNRS-Rhodia-UPenn Complex Assemblies of Soft Matter collaboration and the Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, China.

First Pair Of Supermassive Black Holes Found By Chandra X-ray Observatory

Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way. Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.

Credit: Chandra Observatory

The black holes are located near the center of the spiral galaxy NGC 3393. Separated by only 490 light years, the black holes are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago. 

"If this galaxy weren't so close, we'd have no chance of separating the two black holes the way we have," said Pepi Fabbiano of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the study that appears in this week's online issue of the journal Nature. "Since this galaxy was right under our noses by cosmic standards, it makes us wonder how many of these black hole pairs we've been missing."
Black Holes
Credit: Chandra Observatory

Previous observations in X-rays and at other wavelengths indicated that a single supermassive black hole existed in the center of NGC 3393. However, a long look by Chandra allowed the researchers to detect and separate the dual black holes. Both black holes are actively growing and emitting X-rays as gas falls towards them and becomes hotter.

When two equal-sized spiral galaxies merge, astronomers think it should result in the formation of a black hole pair and a galaxy with a disrupted appearance and intense star formation. A well-known example is the pair of supermassive black holes in NGC 6240, which is located about 330 million light years from Earth.

However, NGC 3393 is a well-organized spiral galaxy, and its central bulge is dominated by old stars. These are unusual properties for a galaxy containing a pair of black holes. Instead, NGC 3393 may be the first known instance where the merger of a large galaxy and a much smaller one, dubbed a "minor merger" by scientists, has resulted in the formation of a pair of supermassive black holes.

In fact, some theories say that minor mergers should be the most common way for black hole pairs to form, but good candidates have been difficult to find because the merged galaxy is expected to look so typical.

"The two galaxies have merged without a trace of the earlier collision, apart from the two black holes," said co-author Junfeng Wang, also from CfA. "If there were a mismatch in size between the two galaxies it wouldn't be a surprise for the bigger one to survive unscathed."

If this were a minor merger, the black hole in the smaller galaxy should have had a smaller mass than the other black hole before their host galaxies started to collide. Good estimates of the masses of both black holes are not yet available to test this idea, although the observations do show that both black holes are more massive than about a million suns. Assuming a minor merger occurred, the black holes should eventually merge after about a billion years.

Both of the supermassive black holes are heavily obscured by dust and gas, which makes them difficult to observe in optical light. Because X-rays are more energetic, they can penetrate this obscuring material. Chandra's X-ray spectra show clear signatures of a pair of supermassive black holes.

The NGC 3393 discovery has some similarities to a possible pair of supermassive black holes found recently by Julia Comerford of the University of Texas at Austin, also using Chandra data. Two X-ray sources, which may be due to supermassive black holes in a galaxy about two billion light years from Earth, are separated by about 6,500 light years.

As in NGC 3393, the host galaxy shows no signs of disturbance or extreme amounts of star formation. However, no structure of any sort, including spiral features, is seen in the galaxy. Also, one of the sources could be explained by a jet, implying only one supermassive black hole is located in the galaxy.

"Collisions and mergers are one of the most important ways for galaxies and black holes to grow," said co-author Guido Risaliti of CfA and the National Institute for Astrophysics in Florence, Italy. "Finding a black hole pair in a spiral galaxy is an important clue in our quest to learn how this happens."

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass. 

Contacts and sources:
Chandra Observatory

For more information about the Chandra mission and this result, including images and other multimedia, visit: http://www.nasa.gov/chandra and http://chandra.si.edu

Hubble Movies Of Star Birth And Fantastic Stellar Jets That Announce New Star Formation

Stars aren't shy about sending out birth announcements. They fire off energetic jets of glowing gas traveling at supersonic speeds in opposite directions through space.

Although astronomers for decades have looked at still pictures of stellar jets, they now can watch movies of them, thanks to NASA's Hubble Space Telescope.
A diverse team of scientists led by astronomer Patrick Hartigan of Rice University in Houston, Texas, has collected enough high-resolution Hubble images over a 14-year period to stitch together time-lapse movies of young jets ejected from three stars.

The moving pictures offer a unique view of stellar phenomena that move and change over just a few years. Most astronomical processes change over timescales that are much longer than a human lifetime.

The movies reveal the motion of the speedy outflows as they tear through their interstellar environments. Never-before-seen details in the jets' structure include knots of gas brightening and dimming over time and collisions between fast-moving and slow-moving material, creating glowing arrowhead features. These phenomena are providing clues about the final stages of a star's birth, offering a peek at how our Sun behaved 4.5 billion years ago.

These images taken by NASA's Hubble Space Telescope show how a bright, clumpy jet ejected from a young star has changed over time.

The jet, called Herbig-Haro 34 (or HH 34), is a signpost of star birth. Several bright regions in the lumpy gas signify where material is slamming into each other, heating up, and glowing. The images show that a couple of bright areas on the right faded over time, as heated material cooled (shown in red). Two regions at left, however, brightened over the 14-year span of observations, pinpointing fresh collision sites. The blue fan-shaped feature at left outlines the edge of the outflow cavity, illuminated by the fledgling star. A small knot of material within the blue feature is either a new jet or magnetic energy being emitted by the star.

"For the first time we can actually observe how these jets interact with their surroundings by watching these time-lapse movies," said Hartigan. "Those interactions tell us how young stars influence the environments out of which they form. With movies like these, we can now compare observations of jets with those produced by computer simulations and laboratory experiments to see what aspects of the interactions we understand and what parts we don't understand."

Hartigan's team's results appeared in the July 20, 2011, issue of The Astrophysical Journal.

Jets are an active, short-lived phase of star formation, lasting only about 100,000 years. They are called Herbig-Haro (HH) objects, named in honor of George Herbig and Guillermo Haro, who studied the outflows in the 1950s. Astronomers don't know what role jets play in the star-formation process or exactly how the star unleashes them.

A star forms from a collapsing cloud of cold hydrogen gas. As the star grows, it gravitationally attracts more matter, creating a large spinning disk of gas and dust around it. Eventually, planets may arise within the disk as dust clumps together.

The disk material gradually spirals onto the star and escapes as high-velocity jets along the star's spin axis. The speedy jets may initially be confined to narrow beams by the star's powerful magnetic field. The jet phase stops when the disk runs out of material, usually a few million years after the star's birth.

Hartigan and his colleagues used the Wide Field Planetary Camera 2 to study jets HH 1, HH 2, HH 34, HH 46, and HH 47. HH 1-HH 2 and HH 46-HH 47 are pairs of jets emanating in opposite directions from single stars. Hubble followed the jets over three epochs: HH 1 and HH 2 in 1994, 1997, and 2007; HH 34 in 1994, 1998, and 2007; and HH 46 and HH 47 in 1994, 1999, and 2008. The jets are roughly 10 times the width of our solar system and zip along at more than 440,000 miles an hour (700,000 kilometers an hour).

All of the outflows are roughly 1,350 light-years from Earth. HH 34, HH 1, and HH 2 reside near the Orion Nebula, in the northern sky. HH 46 and HH 47 are in the southern constellation Vela.

Computer software wove together the years' worth of observations, generating movies that show continuous motion. The movies support previous observations revealing that the twin jets are not ejected in a steady stream, like water flowing from a garden hose. Instead, they are launched sporadically in clumps. The beaded-jet structure might be like a "ticker tape," recording how material episodically fell onto the star.

The movies show that the clumpy gas in the jets is moving at different speeds like traffic on a freeway. When fast-moving blobs "rear-end" slower gas, bow shocks arise as the material heats up. Bow shocks are glowing waves of material similar to waves produced by the bow of a ship plowing through water. In HH 2, for example, several bow shocks can be seen where several fast-moving clumps bunch up like cars in a traffic jam. In another jet, HH 34, a grouping of merged bow shocks reveals regions that brighten and fade over time as the heated material cools where the shocks intersect.

In other areas of the jets, bow shocks form from encounters with the surrounding dense gas cloud. In HH 1 a bow shock appears at the top of the jet as it grazes the edge of a dense gas cloud. New glowing knots of material also appear. These knots may represent gas from the cloud being swept up by the jet, just as a swift-flowing river pulls along mud from the shoreline.

The movies also provide evidence that the inherent clumpy nature of the jets begins near the newborn stars. In HH 34 Hartigan traced a glowing knot to within about 9 billion miles of the star.

"Taken together, our results paint a picture of jets as remarkably diverse objects that undergo highly structured interactions between material within the outflow and between the jet and the surrounding gas," Hartigan explained. "This contrasts with the bulk of the existing simulations, which depict jets as smooth systems."

The details revealed by Hubble were so complex that Hartigan consulted with experts in fluid dynamics from Los Alamos National Laboratory in New Mexico, the Atomic Weapons Establishment in England, and General Atomics in San Diego, Calif., as well as computer specialists from the University of Rochester in New York. Motivated by the Hubble results, Hartigan's team is now conducting laboratory experiments at the Omega Laser facility in New York to understand how supersonic jets interact with their environment.

"The fluid dynamicists immediately picked up on an aspect of the physics that astronomers typically overlook, and that led to a different interpretation for some of the features we were seeing," Hartigan explained. "The scientists from each discipline bring their own unique perspectives to the project, and having that range of expertise has proved invaluable for learning about this critical phase of stellar evolution."

Hartigan's research team consists of Adam Frank of the University of Rochester in New York; John Foster and Paula Rosen of the Atomic Weapons Establishment in Aldermaston, England; Bernie Wilde, Rob Coker, and Melissa Douglas of Los Alamos National Laboratory in New Mexico; and Brent Blue and Freddy Hansen of General Atomics in San Diego, Calif.

Contacts and sources:
Hubble Space Telescope News Center

Berkeley Lab Researchers Develop Inexpensive Technique For Making High Quality Nanowire Solar Cells

Solar or photovoltaic cells represent one of the best possible technologies for providing an absolutely clean and virtually inexhaustible source of energy to power our civilization. 

Schematic shows how to make core/shell nanowire solar cell starting from left with a CdS nanowire (green) that is dipped in CuCl where cation exchange reaction creates a Cu2S shell coating (brown). Metal contacts are then deposited on the CdS core and Cu2S shell.
Credit: Image courtesy of Yang, et. al

However, for this dream to be realized, solar cells need to be made from inexpensive elements using low-cost, less energy-intensive processing chemistry, and they need to efficiently and cost-competitively convert sunlight into electricity. A team of researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) has now demonstrated two out of three of these requirements with a promising start on the third.

Peidong Yang, a chemist with Berkeley Lab's Materials Sciences Division, led the development of a solution-based technique for fabricating core/shell nanowire solar cells using the semiconductors cadmium sulfide for the core and copper sulfide for the shell. These

This scanning electron microscopy image shows three solar cells in series on a single nanowire with the core–shell regions marked by brown lines.
Credit: Image courtesy of Yang, et. al

inexpensive and easy-to-make nanowire solar cells boasted open-circuit voltage and fill factor values superior to conventional planar solar cells. Together, the open-circuit voltage and fill factor determine the maximum energy that a solar cell can produce. In addition, the new nanowires also demonstrated an energy conversion efficiency of 5.4-percent, which is comparable to planar solar cells.

"This is the first time a solution based cation-exchange chemistry technique has been used for the production of high quality single-crystalline cadmium sulfide/copper sulfide core/shell nanowires," Yang says. "Our achievement, together with the increased light absorption we have previously demonstrated in nanowire arrays through light trapping, indicates that core/shell nanowires are truly promising for future solar cell technology."

Yang, who holds a joint appointment with the University of California (UC) Berkeley, is the corresponding author of a paper reporting this research that appears in the journal Nature Nanotechnology. The paper is titled "Solution-processed core–shell nanowires for efficient photovoltaic cells." Co-authoring this paper with Yang were Jinyao Tang, Ziyang Huo, Sarah Brittman and Hanwei Gao.

Typical solar cells today are made from ultra-pure single crystal silicon wafers that require about 100 micrometers in thickness of this very expensive material to absorb enough solar light. Furthermore, the high-level of crystal purification required makes the fabrication of even the simplest silicon-based planar solar cell a complex, energy-intensive and costly process.

A highly promising alternative would be semiconductor nanowires – one-dimensional strips of materials whose width measures only one-thousandth that of a human hair but whose length may stretch up to the millimeter scale. Solar cells made from nanowires offer a number of advantages over conventional planar solar cells, including better charge separation and collection capabilities, plus they can be made from Earth abundant materials rather than highly processed silicon. To date, however, the lower efficiencies of nanowire-based solar cells have outweighed their benefits.

Berkeley Lab chemist Peidong Yang is a leading authority on semiconductor nanowires.
Credit: LBNL

"Nanowire solar cells in the past have demonstrated fill factors and open-circuit voltages far inferior to those of their planar counterparts," Yang says. "Possible reasons for this poor performance include surface recombination and poor control over the quality of the p–n junctions when high-temperature doping processes are used."

At the heart of all solar cells are two separate layers of material, one with an abundance of electrons that function as a negative pole, and one with an abundance of electron holes (positively-charged energy spaces) that function as a positive pole. When photons from the sun are absorbed, their energy is used to create electron-hole pairs, which are then separated at the p-n junction – the interface between the two layers - and collected as electricity.

About a year ago, working with silicon, Yang and members of his research group developed a relatively inexpensive way to replace the planar p-n junctions of conventional solar cells with a radial p-n junction, in which a layer of n-type silicon formed a shell around a p-type silicon nanowire core. This geometry effectively turned each individual nanowire into a photovoltaic cell and greatly improved the light-trapping capabilities of silicon-based photovoltaic thin films.

Now they have applied this strategy to the fabrication of core/shell nanowires using cadmium sulfide and copper sulfide, but this time using solution chemistry. These core/shell nanowires were prepared using a solution-based cation (negative ion) exchange reaction that was originally developed by chemist Paul Alivisatos and his research group to make quantum dots and nanorods. Alivisatos is now the director of Berkeley Lab, and UC Berkeley's Larry and Diane Bock Professor of Nanotechnology.

"The initial cadmium sulfide nanowires were synthesized by physical vapor transport using a vapor–liquid–solid (VLS) mechanism rather than wet chemistry, which gave us better quality material and greater physical length, but certainly they can also be made using solution process" Yang says. "The as-grown single-crystalline cadmium sulfide nanowires have diameters of between 100 and 400 nanometers and lengths up to 50 millimeters."

The cadmium sulfide nanowires were then dipped into a solution of copper chloride at a temperature of 50 degrees Celsius and kept there for 5 to 10 seconds. The cation exchange reaction converted the surface layer of the cadmium sulfide into a copper sulfide shell.

"The solution-based cation exchange reaction provides us with an easy, low-cost method to prepare high-quality hetero-epitaxial nanomaterials," Yang says. "Furthermore, it circumvents the difficulties of high-temperature doping and deposition for typical vapor phase production methods, which suggests much lower fabrication costs and better reproducibility. All we really need are beakers and flasks for this solution-based process. There's none of the high fabrication costs associated with gas-phase epitaxial chemical vapor deposition and molecular beam epitaxy, the techniques most used today to fabricate semiconductor nanowires."

Yang and his colleagues believe they can improve the energy conversion efficiency of their solar cell nanowires by increasing the amount of copper sulfide shell material. For their technology to be commercially viable, they need to reach an energy conversion efficiency of at least ten-percent.

This research was supported by the DOE Office of Science.

Contacts and sources:
Lynn Yarris
DOE/Lawrence Berkeley National Laboratory

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 12 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit www.lbl.gov.

Tiny Implantable Oxygen Generators Boost Effectiveness Of Anticancer Treatment

Researchers have created and tested miniature devices that are implanted in tumors to generate oxygen, boosting the killing power of radiation and chemotherapy.

The technology is designed to treat solid tumors that are hypoxic at the center, meaning the core contains low oxygen levels.

Researchers have created and tested a miniature device, seen here, that can be implanted in tumors to generate oxygen, boosting the killing power of radiation and chemotherapy. The technology is designed to treat solid tumors that are hypoxic at the center, meaning the core contains low oxygen levels. The device (right) fits inside a tube (left) that can then be inserted into a tumor with a biopsy needle.
Credit: Birck Nanotechnology Center, Purdue University

"This is not good because radiation therapy needs oxygen to be effective," said Babak Ziaie, a Purdue University professor of electrical and computer engineering and biomedical engineering. "So the hypoxic areas are hard to kill. Pancreatic and cervical cancers are notoriously hypoxic. If you generate oxygen you can increase the effectiveness of radiation therapy and also chemotherapy."

The new "implantable micro oxygen generator" is an electronic device that receives ultrasound signals and uses the energy to generate a small voltage to separate oxygen and hydrogen from water ╨ a chemical operation called water electrolysis.

This diagram shows the design of a miniature device that can be implanted in tumors to generate oxygen, boosting the killing power of radiation and chemotherapy.
Credit: Birck Nanotechnology Center, Purdue University

"We are putting these devices inside tumors and then exposing the tumors to ultrasound," Ziaie said. "The ultrasound energy powers the device, generating oxygen.

The devices were created at the Birck Nanotechnology Center in the university's Discovery Park. Purdue researchers are working with Song-Chu (Arthur) Ko, an assistant professor of clinical radiation oncology at the Indiana University School of Medicine.

Researchers have tested the devices in pancreatic tumors implanted in mice, showing they generated oxygen and shrunk tumors faster than tumors without the devices. The devices are slightly less than one centimeter long and are inserted into tumors with a hypodermic biopsy needle.

"Most of us have been touched by cancer in one way or another," Ziaie said. "My father is a cancer survivor, and he went through many rounds of very painful chemotherapy. This is a new technology that has the potential to improve the effectiveness of such therapy."

Findings are detailed in a research paper appearing online this month in Transactions on Biomedical Engineering. The paper was written by research assistant professor Teimour Maleki, doctoral students Ning Cao and Seung Hyun Song, Ko and Ziaie.

"The implantable mini oxygen generator project is one of 11 projects the Alfred Mann Institute for Biomedical Development at Purdue University (AMIPurdue) has sponsored," Ziaie said. "AMIPurdue has been instrumental in providing the development funding of roughly $500,000 on this project. And beyond funding, the AMIPurdue team has also helped us with market research, physician feedback, industry input, as well as intellectual property and regulatory strategy. We have been able to accomplish a great deal in a short time due to the collaborative effort with AMIPurdue."

A patent application has been filed for the design.

Future work may focus on redesigning the device to make it more practical for manufacturing and clinical trials.

Contacts and sources:
Emil Venere
Purdue University

Computer Uses Brain Images To Predict The Words On A Person's Mind

In an effort to understand what happens in the brain when a person reads or considers such abstract ideas as love or justice, Princeton researchers have for the first time matched images of brain activity with categories of words related to the concepts a person is thinking about. The results could lead to a better understanding of how people consider meaning and context when reading or thinking.

Princeton researchers developed a method to determine the probability of various words being associated with the object a person thought about during a brain scan. They produced color-coded figures that illustrate the probability of words within the Wikipedia article about the object the participant saw during the scan actually being associated with the object. The more red a word is, the more likely a person is to associate it, in this case, with "cow." On the other hand, bright blue suggests a strong correlation with "carrot." Black and grey "neutral" words had no specific association or were not considered at all.
Credit: Courtesy of Francisco Pereira

The researchers report in the journal Frontiers in Human Neuroscience that they used functional magnetic resonance imaging (fMRI) to identify areas of the brain activated when study participants thought about physical objects such as a carrot, a horse or a house. The researchers then generated a list of topics related to those objects and used the fMRI images to determine the brain activity that words within each topic shared. For instance, thoughts about "eye" and "foot" produced similar neural stirrings as other words related to body parts.

Once the researchers knew the brain activity a topic sparked, they were able to use fMRI images alone to predict the subjects and words a person likely thought about during the scan. This capability to put people's brain activity into words provides an initial step toward further exploring themes the human brain touches upon during complex thought.

"The basic idea is that whatever subject matter is on someone's mind -- not just topics or concepts, but also, emotions, plans or socially oriented thoughts -- is ultimately reflected in the pattern of activity across all areas of his or her brain," said the team's senior researcher, Matthew Botvinick, an associate professor in Princeton's Department of Psychology and in the Princeton Neuroscience Institute.

"The long-term goal is to translate that brain-activity pattern into the words that likely describe the original mental 'subject matter,'" Botvinick said. "One can imagine doing this with any mental content that can be verbalized, not only about objects, but also about people, actions and abstract concepts and relationships. This study is a first step toward that more general goal.

"If we give way to unbridled speculation, one can imagine years from now being able to 'translate' brain activity into written output for people who are unable to communicate otherwise, which is an exciting thing to consider. In the short term, our technique could be used to learn more about the way that concepts are represented at the neural level -- how ideas relate to one another and how they are engaged or activated."

The research, which was published Aug. 23, was funded by a grant from the National Institute of Neurological Disease and Stroke, part of the National Institutes of Health.

Depicting a person's thoughts through text is a "promising and innovative method" that the Princeton project introduces to the larger goal of correlating brain activity with mental content, said Marcel Just, a professor of psychology at Carnegie Mellon University. The Princeton researchers worked from brain scans Just had previously collected in his lab, but he had no active role in the project.

"The general goal for the future is to understand the neural coding of any thought and any combination of concepts," Just said. "The significance of this work is that it points to a method for interpreting brain activation patterns that correspond to complex thoughts."

Tracking the brain's 'semantic threads'

Largely designed and conducted in Botvinick's lab by lead author and Princeton postdoctoral researcher Francisco Pereira, the study takes a currently popular approach to neuroscience research in a new direction, Botvinick said. He, Pereira and coauthor Greg Detre, who earned his Ph.D. from Princeton in 2010, based their work on various research endeavors during the past decade that used brain-activity patterns captured by fMRI to reconstruct pictures that participants viewed during the scan.

"This 'generative' approach -- actually synthesizing something, an artifact, from the brain-imaging data -- is what inspired us in our study, but we generated words rather than pictures," Botvinick said.

"The thought is that there are many things that can be expressed with language that are more difficult to capture in a picture. Our study dealt with concrete objects, things that are easy to put into a picture, but even then there was an interesting difference between generating a picture of a chair and generating a list of words that a person associates with 'chair.'"

Those word associations, lead author Pereira explained, can be thought of as "semantic threads" that can lead people to think of objects and concepts far from the original subject matter yet strangely related.

"Someone will start thinking of a chair and their mind wanders to the chair of a corporation then to Chairman Mao -- you'd be surprised," Pereira said. "The brain tends to drift, with multiple processes taking place at the same time. If a person thinks about a table, then a lot of related words will come to mind, too. And we thought that if we want to understand what is in a person's mind when they think about anything concrete, we can follow those words."

Pereira and his co-authors worked from fMRI images of brain activity that a team led by Just and fellow Carnegie Mellon researcher Tom Mitchell, a professor of computer science, published in the journal Science in 2008. For those scans, nine people were presented with the word and picture of five concrete objects from 12 categories. The drawing and word for the 60 total objects were displayed in random order until each had been shown six times. Each time an image and word appeared, participants were asked to visualize the object and its properties for three seconds as the fMRI scanner recorded their brain activity.

Matching words and brain activity with related topics

Separately, Pereira and Detre constructed a list of topics with which to categorize the fMRI data. They used a computer program developed by Princeton Associate Professor of Computer Science David Blei to condense 3,500 articles about concrete objects from the online encyclopedia Wikipedia into all the topics the articles covered. The articles included a broad array of subjects, such as an airplane, heroin, birds and manual transmission. The program came up with 40 possible topics -- such as aviation, drugs, animals or machinery -- with which the articles could relate. Each topic was defined by the words most associated with it.

The computer ultimately created a database of topics and associated words that were free from the researchers' biases, Pereira said.

"We let the software discern the factors that make up meaning rather than stipulating it ourselves," he said. "There is always a danger that we could impose our preconceived notions of the meaning words have. Plus, I can identify and describe, for instance, a bird, but I don't think I can list all the characteristics that make a bird a bird. So instead of postulating, we let the computer find semantic threads in an unsupervised manner."

The topic database let the researchers objectively arrange the fMRI images by subject matter, Pereira said. To do so, the team searched the brain scans of related objects for similar activity to determine common brain patterns for an entire subject, Pereira said. The neural response for thinking about "furniture," for example, was determined by the common patterns found in the fMRI images for "table," "chair," "bed," "desk" and "dresser." At the same time, the team established all the words associated with "furniture" by matching each fMRI image with related words from the Wikipedia-based list.

Based on the similar brain activity and related words, Pereira, Botvinick and Detre concluded that the same neural response would appear whenever a person thought of any of the words related to furniture, Pereira said. And a scientist analyzing that brain activity would know that person was thinking of furniture. The same would follow for any topic.

Using images to predict the words on a person's mind
Finally, to ensure their method was accurate, the researchers conducted a blind comparison of each of the 60 fMRI images against each of the others. Without knowing the objects the pair of scans pertained to, Pereira and his colleagues estimated the presence of certain topics on a participant's mind based solely on the fMRI data. Knowing the applicable Wikipedia topics for a given brain image, and the keywords for each topic, they could predict the most likely set of words associated with the brain image.

The researchers found that they could confidently determine from an fMRI image the general topic on a participant's mind, but that deciphering specific objects was trickier, Pereira said. For example, they could compare the fMRI scan for "carrot" against that for "cow" and safely say that at the time the participant had thought about vegetables in the first example instead of animals. In turn, they could say that the person most likely thought of other words related to vegetables, as opposed to words related to animals.

On the other hand, when the scan for "carrot" was compared to that for "celery," Pereira and his colleagues knew the participant had thought of vegetables, but they could not identify related words unique to either object.

One aim going forward, Pereira said, is to fine-tune the group's method to be more sensitive to such detail. In addition, he and Botvinick have begun performing fMRI scans on people as they read in an effort to observe the various topics the mind accesses.

"Essentially," Pereira said, "we have found a way to generally identify mental content through the text related to it. We can now expand that capability to even further open the door to describing thoughts that are not amenable to being depicted with pictures."

Contacts and sources:
Morgan Kelly
Princeton University

The Dark Side Of Green: Solar Industry Responsible For Lead Emissions In Developing Countries

Solar power is not all sunshine; it has a dark side—particularly in developing countries, according to a new study by a University of Tennessee, Knoxville, engineering professor

Solar power is not all sunshine. It has a dark side—particularly in developing countries, according to a new study by a University of Tennessee, Knoxville, engineering professor.

A study by Chris Cherry, assistant professor in civil and environmental engineering, found that solar power heavily reliant on lead batteries has the potential to release more than 2.4 million tons of lead pollution in China and India.

Lead poisoning causes numerous adverse health effects, including damage to the central nervous system, the kidneys, the cardiovascular system, and the reproductive system. In children, blood lead concentration is associated with learning impairments, as well as hyperactive and violent behavior.

His study, co-authored with Perry Gottesfeld of Occupational Knowledge International (OK International), appears in the September issue of the journal Energy Policy.

Lead pollution predicted to result from investments in solar power by 2022 is equivalent to one-third of current global lead production. The researchers, who relied on official government plans for deploying solar power to make these projections, also found that the countries have large amounts of lead leak into the environment from mining, smelting, battery manufacturing, and recycling—33 percent in China and 22 percent in India. Also, a large percentage of new solar power systems continues to be reliant on lead batteries for energy storage due to the inadequate power grid in these countries.

The study's release comes on the heels of reports of a large number of mass lead poisoning incidents around lead battery recycling and manufacturing plants in China and the announcement that the country recently closed 583 of these facilities.

"Investments in environmental controls in the lead battery industry, along with improvements in battery take-back policies, are needed to complement deployment of solar power in these countries," said Cherry. "Without improvements, it is increasingly clear that the use of lead batteries will contribute to environmental contamination and lead poisoning among workers and children."

The battery industry is the largest consumer of lead, using approximately 80 percent of global lead production. Lead battery manufacturing is growing rapidly in much of the world to meet demand for batteries for solar power and other applications. With the authors' projected emissions, they say this will impact public health and contribute to environmental contamination.

"The solar industry has to step up and take responsibility for ensuring that their lead battery suppliers are operating with adequate controls as long as they are going to be reliant on this technology," said Gottesfeld. "Without major improvements in the manufacturing and recycling lead batteries in these countries, we expect that lead poisoning will increase as the industry grows."

The projections outlined in the study, while based on plans articulated by these two countries, are likely to be repeated throughout much of the developing world, such as in Africa.

OK International is a nongovernmental organization dedicated to improving public health in developing countries through innovative strategies to reduce exposures to industrial pollutants. For more information, visit www.okinternational.org.

Contacts and sources:
Whitney Holmes
University of Tennessee at Knoxville