Is nanosilver toxic?

Feb. 28, 2013 ? According to Finnish-Estonian joint research with data obtained on two crustacean species, there is apparently no reason to consider silver nanoparticles more dangerous for aquatic ecosystems than silver ions. The results were reported in the journal Environmental Science and Pollution Research late last year. Jukka Niskanen has utilised the same polymerisation and coupling reactions in his doctoral dissertation studying several hybrid nanomaterials, i.e. combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles. Niskanen will defend his doctoral thesis at the University of Helsinki in April.

Part of the magic of nano-science is that on the scale of a billionth of a metre, matter and materials behave in ways that are not yet known. Neither is it always known what types of effects the nano version of the parent matter will have on its environment.

-Due to the fact that silver in nanoparticle form is bactericidal and also fungicidal and also prevents the reproduction of those organisms, it is now used in various consumer goods ranging from wound dressing products to sportswear, says Jukka Niskanen from the Laboratory of Polymer Chemistry at the University of Helsinki, Finland.

While the usefulness of silver has been established, the debate over the toxicity mechanisms of its various forms to microorganisms but also to non-target species continues. Anne Kahru, Head of the Laboratory of Environmental Toxicology at the National Institute of Chemical Physics and Biophysics, Estonia, talks about a whole new field of ecotoxicology: nanoecotoxicology.

So far, little is known about the environmental effects of silver nanoparticles and their toxicity to aquatic organisms. A joint study from the University of Helsinki and the National Institute of Chemical Physics and Biophysics (Tallinn, Estonia), Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus , shows that silver nanoparticles are apparently no more hazardous to aquatic ecosystems than a water-soluble silver salt. The study compared the ecotoxicity of silver nanoparticles and a water-soluble silver salt.

-Our conclusion was that the environmental risks caused by silver nanoparticles are seemingly not higher than those caused by a silver salt. However, more research is required to reach a clear understanding of the safety of silver-containing particles, Niskanen says.

Indeed, silver nanoparticles were found to be ten times less toxic than the soluble silver nitrate -- a soluble silver salt used for the comparison..

The bioavailability of silver varies in different test media

To explain this phenomenon, the researchers refer to the variance in the bioavailability of silver to crustaceans in different tested media.

University lecturer Olli-Pekka Penttinen from the Department of Environmental Sciences of the University of Helsinki goes on to note that the inorganic and organic compounds dissolved in natural waters (such as humus), water hardness and sulfides have a definite impact on the bioavailability of silver. Due to this, the toxicity of both types of tested nanoparticles and the silver nitrate measured in the course of the study was lower in natural water than in artificial fresh water.

The toxicity of silver nanoparticles and silver ions was studied using two aquatic crustaceans, a water flea (Daphnia magna) and a fairy shrimp (Thamnocephalus platyurus). Commercially available protein-stabilised particles and particles coated with a water-soluble, non-toxic polymer, specifically synthesised for the purpose, were used in the study. First, the polymers were produced utilising a controlled radical polymerisation method. Synthetic polymer-grafted silver particles were then produced by attaching the water-soluble polymer to the surface of the silver with a sulfur bond.

Jukka Niskanen has utilised such polymerisation and coupling reactions in his doctoral dissertation, Polymeric and hybrid materials: polymers on particle surfaces and air-water interfaces, studying several hybrid nanomaterials , i.e., combinations of synthetic polymers and inorganic (gold, silver and montmorillonite) nanoparticles. Niskanen will defend his doctoral thesis in the field of polymer chemistry at the University of Helsinki in April 2013.

It was previously known from other studies and research results that silver changes the functioning of proteins and enzymes. It has also been shown that silver ions can prevent the replication of DNA. Concerning silver nanoparticles, tests conducted on various species of bacteria and fungi have indicated that their toxicity varies. For example, gram-negative bacteria such as Escherichia coli are more sensitive to silver nanoparticles than gram-positive ones (such as Staphylococcus aureus). The difference in sensitivity is caused by the structural differences of the cell membranes of the bacteria. The cellular toxicity of silver nanoparticles in mammals has been studied as well. It has been suggested that silver nanoparticles enter cells via endocytosis and then function in the same manner as in bacterial cells, damaging DNA and hindering cell respiration. Electron microscope studies have shown that human skin is permeable to silver nanoparticles and that the permeability of damaged skin is up to four times higher than that of healthy skin.

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The above story is reprinted from materials provided by Helsingin yliopisto (University of Helsinki), via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Irina Blinova, Jukka Niskanen, Paula Kajankari, Liina Kanarbik, Aleksandr K?kinen, Heikki Tenhu, Olli-Pekka Penttinen, Anne Kahru. Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus. Environmental Science and Pollution Research, 2012; DOI: 10.1007/s11356-012-1290-5

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_environment/~3/Dadnq8WV2ZE/130228080338.htm

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3-D computing prototype puts your hands inside the screen

Devin Coldewey , NBC News ? ? ? 30 min.

Attendees of the latest TED conference got a look at a futuristic device called SpaceTop where the user views a 3-D workspace through a transparent display, manipulating the on-screen elements with just their hands. It won't be on shelves any time soon, but it does pique the imagination.

The demonstration was by Jinha Lee, an MIT graduate student who undertook an internship at Microsoft's Applied Science group to develop a 3-D desktop. Part of that project was creating a new method for users to interact with the computer.

Mice and touchscreens, of course, really only let one interact along two dimensions ? you can scroll left, right, up, and down, but going in and out must be done with 2-D gestures like pinches, whereas in real life you would just move your hand forward or back.

Lee's work focused on creating an interface though which one could move one's hand naturally and interact with familiar elements like windows and documents. The result is still rather rough, but it's promising.

The transparent display is equipped with a camera that tracks the user's head and adjusts the perspective on the 3-D desktop "under" it. Meanwhile, a second camera watches the user's hands and determines their position in three dimensions.

While it's still limited to a few demo applications, it's fascinating to watch: Grabbing a file from a stack is as easy as plucking it out, and when you need to type, just drop your hands onto the built-in keyboard.

Among the many challenges of developing such a system is that there is essentially no software written for it. Every operating system with which an average user might be familiar is built around the idea of a flat display navigated by a mouse or touchscreen. So Lee's had to be built from scratch.

As such, it's still very much just a concept or work in progress. His original work was done in late 2011, and the "core design and framework" were presented at Microsoft's TechForum in 2012. But this week's TED demonstration was much farther along and the first time it has been shown so publicly.

Whether this kind of interaction becomes commonplace or not (devices like the Oculus Rift and Leap Motion also present alternative input methods and are farther along in development), it's still a thrill to see something like this that seems to be science fiction made fact.

Devin Coldewey is a contributing writer for NBC News Digital. His personal website is coldewey.cc.

Source: http://www.nbcnews.com/technology/futureoftech/3-d-computing-prototype-puts-your-hands-inside-screen-1C8600002

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Good Reads: A family in isolation, Pakistan's difficult present, Africa's biggest game

This week's good reads includes a profile of a Russian family that lived in isolation for 40 years, a young professor's return to Pakistan from the United States after 13 years, and efforts to end big game hunting in Africa.

By Cricket Fuller,?Staff writer / February 12, 2013

A lion rests in the grass plains of the Maasai Mara game reserve in Kenya.

Melanie Stetson Freeman/Staff/File

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In 1978, a group of Soviet geologists trying to land their helicopter in the taiga (thick wilderness) of remote Siberia saw startling evidence of human life. Soon they found the Lykov family ? who had been living in an encampment for more than 40 years with no contact with the outside world.

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Mike Dash, writing for Smithsonian.com, recounts their incredible story and the chance meeting that brought it to light. The Lykovs were Old Believers, a fundamentalist Russian Orthodox sect that had been persecuted since the days of Peter the Great. In 1936, after his brother was shot and killed by a Communist patrol, Karp Lykov took his wife, Akulina, and two young children and fled into the forest.

For 40 years the family eked out a living in the unforgiving Siberian wilderness, ?permanently on the edge of famine.? Two more children were born. Akulina died of starvation in 1961 when a June snow destroyed the family?s small crop. The Soviet scientists were astounded to learn that the family had no knowledge of World War II, the moon landing, or any other major development of modern society of the past half century. The two youngest children had never seen a person outside their own family.

But over the next few years, says Mr. Dash, as ?the Soviet geologists got to know the Lykov family, they realized that they had underestimated their abilities and intelligence.?

The family at first spurned, then gradually accepted most of the modern technology they saw at the scientists? research camp nearby. When, during this period, three of the Lykovs died, scientists tried to convince Karp and his daughter Agafia to leave the wilderness, but they chose to rebuild their small cabin and stay on.

After Karp died in 1988, Agafia, the youngest child, again refused to leave the life her family had forged ? and the only one she has ever known. ?A quarter of a century later, now in her seventies herself, this child of the taiga lives on alone, high above the Abakan.?

Pakistan, a forbidden love

For Taymiya Zaman, Pakistan is not Osama bin Laden or blasphemy laws or drone attacks. It is her homeland, a place of rich culture and history, struggling under the weight of change and competing stereotypes. But for many people in the United States, where she is a history professor, Pakistan is a harbor for terrorists or the scene of poor brown children waiting for Western benevolence.

Ms. Zaman?s rich personal essay appears in Tanqeed, an online magazine of politics and culture that focuses on Pakistan. Her essay first ran in the quarterly magazine Critical Muslim.

Tired of the questions and accusations surrounding her nationality, Zaman ?builds a wall? around Pakistan. Finally, weary of the disconnect, and against the advice of her colleagues, she returns to Lahore for a sabbatical year. It will be the longest she?s been home since leaving for college 13 years earlier.

She describes the homecoming: ?Landing in Karachi is like running into the arms of a lover you?ve been forbidden to see for years.? Once there, however, she gains ?the realization that I can?t hide from the things about being here that leave me troubled and edgy.? She is heckled by a bearded student who accuses her of disrespecting Islam. The traffic congestion is overwhelming.

Zaman returns to her teaching position in San Francisco with newfound appreciation for the US and enduring love for her Pakistan. ?I know the newspaper images that fuel Pakistan-bashing. I know the minefields of personal sorrow and betrayal that don?t make it to newspapers. I also know a Pakistan beneath these images that is rich with extraordinary possibilities....?

Take photos, not big game, on safari

On Foreign Policy Blogs, Daniel Donovan writes of Botswana?s recent decision to ban big-game trophy hunting by 2014. Zambia followed suit soon after by banning hunting of lions and leopards.

Botswana?s move has inspired both praise and criticism. In spite of short-term setbacks to the hunting industry, Mr. Donovan points to Kenya?s thriving nonhunting safari business as a sign of greater long-term economic gains in banning trophy hunting.

?While hunters and hunting advocates point to large profits being made in hunting of animals in Africa ... the reality is that photographic tourism far outdistances any money made in hunting safaris,? he writes. Big-game hunting in Africa has always held an allure for the rich and famous, but one study in Botswana showed that trophy hunting only represented approximately 0.1 percent of gross domestic product, as opposed to phototourism, which yields 11 percent. And as Zambia?s tourism minister, Sylvia Masebo, put it: ?Tourists come to Zambia to see the lion and if we lose the lion we will be killing our tourism industry.?

Donovan concedes that ?[c]ritics of the decision argue that it will encourage poaching over the long-term,? which has reached alarming levels in Kenya. But ?even countries that encourage trophy hunting are not immune from illegal hunting,? as revelations of poaching violations in South Africa and Tanzania show.

?Ultimately, each country must decide which direction will benefit them both ecologically and economically.?

Source: http://rss.csmonitor.com/~r/csmonitor/globalnews/~3/rFq_EnLICYg/Good-Reads-A-family-in-isolation-Pakistan-s-difficult-present-Africa-s-biggest-game

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Mexico arrests head of teacher's union on suspicion of fraud

MEXICO CITY (Reuters) - Mexico on Tuesday arrested Elba Esther Gordillo, the powerful head of the country's teachers' union, on suspicion of embezzling the union's funds, the Mexican attorney general said.

Authorities accuse Gordillo, who is viewed as one of the key obstacles to education reform in Mexico, of siphoning off millions of pesos of union money into private accounts, Jesus Murillo told reporters at a news conference.

"Clearly, we're facing a case in which the money of education workers has been misused illegally for the benefit of various people, including Elba Esther Gordillo," Murillo said. "Under this government nobody is above the law."

The arrest of Gordillo, who critics have for years accused of corruption, came a day after the Mexican government signed a broad education reform into law.

The Mexican teachers' union fought against the law, which limits union control over hiring and teaching standards, and aims to improve Mexico's failing school system.

(Reporting by Gabriel Stargardter; editing by Jackie Frank)

Source: http://news.yahoo.com/mexico-arrests-head-teachers-union-suspicion-fraud-022004391.html

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Linking insulin to learning: Insulin-like molecules play critical role in learning and memory

Feb. 26, 2013 ? Though it's most often associated with disorders like diabetes, Harvard researchers have shown how the signaling pathway of insulin and insulin-like peptides plays another critical role in the body -- helping to regulate learning and memory.

In addition to showing that the insulin-like peptides play a critical role in regulating the activity of neurons involved in learning and memory, a team of researchers led by Yun Zhang, Associate Professor of Organismic and Evolutionary Biology, show that the interaction between the molecules can fine-tune how, or even if, learning takes place. Their work is described in a February 6 paper in Neuron.

"People think of insulin and diabetes, but many metabolic syndromes are associated with some types of cognitive defects and behavioral disorders, like depression or dementia," Zhang said. "That suggests that insulin and insulin-like peptides may play an important role in neural function, but it's been very difficult to nail down the underlying mechanism, because these peptides do not have to function through synapses that connect different neurons in the brain"

To get at that mechanism, Zhang and colleagues turned to an organism whose genome and nervous system are well described and highly accessible by genetics -- C. elegans.

Using genetic tools, researchers altered the small, transparent worms by removing their ability to create individual insulin-like compounds. These new "mutant" worms were then tested to see whether they would learn to avoid eating a particular type of bacteria that is known to infect the worms. Tests showed that while some worms did learn to steer clear of the bacteria, others didn't -- suggesting that removing a specific insulin-like compound halted the worms' ability to learn.

Researchers were surprised to find, however, that it wasn't just removing the molecules that could make the animals lose the ability to learn -- some peptide was found to inhibit learning.

"We hadn't predicted that we would find both positive and negative regulators from these peptides," Zhang said. "Why does the animal need this bidirectional regulation of learning? One possibility is that learning depends on context. There are certain things you want to learn -- for example, the worms in these experiments wanted to learn that they shouldn't eat this type of infectious bacteria. That's a positive regulation of the learning. But if they needed to eat, even if it is a bad food, to survive, they would need a way to suppress this type of learning."

Even more surprising for Zhang and her colleagues was evidence that the various insulin-like molecules could regulate each other.

"Many animals, including the humans, have multiple insulin-like molecules and it appears that these molecules can act like a network," she said. "Each of them may play a slightly different role in the nervous system, and they function together to coordinate the signaling related to learning and memory. By changing the way the molecules interact, the brain can fine tune learning in a host of different ways."

Going forward, Zhang said she hopes to characterize more of the insulin-like peptides as a way of better understanding how the various molecules interact, and how they act on the neural circuits for learning and memory.

Understanding how such pathways work could one day help in the development of treatment for a host of cognitive disorders, including dementia.

"The signaling pathways for insulin and insulin-like peptides are highly conserved in mammals, including the humans," Zhang said. "There is even some preliminary evidence that insulin treatment, in some cases, can improve cognitive function. That's one reason we believe that if we understand this mechanism, it will help us better understand how insulin pathways are working in the human brain."

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The above story is reprinted from materials provided by Harvard University.

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Journal Reference:

1. Zhunan Chen, Michael Hendricks, Astrid Cornils, Wolfgang Maier, Joy Alcedo, Yun Zhang. Two Insulin-like Peptides Antagonistically Regulate Aversive Olfactory Learning in C.?elegans. Neuron, 2013; 77 (3): 572 DOI: 10.1016/j.neuron.2012.11.025

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/~3/HFukdteMQE0/130226162837.htm

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2,000 pound turtle could be extinct within 20 years

Feb. 26, 2013 ? An international team led by the University of Alabama at Birmingham (UAB) has documented a 78 percent decline in the number of nests of the critically endangered leatherback sea turtle (Dermochelys coriacea) at the turtle's last stronghold in the Pacific Ocean.

The study, published online February 26in the Ecological Society of America's scientific online journal Ecosphere, reveals leatherback nests at Jamursba Medi Beach in Papua Barat, Indonesia -- which accounts for 75 percent of the total leatherback nesting in the western Pacific -- have fallen from a peak of 14,455 in 1984 to a low of 1,532 in 2011. Less than 500 leatherbacks now nest at this site annually.

Thane Wibbels, Ph.D., a professor of reproductive biology at UAB and member of a research team that includes scientists from State University of Papua (UNIPA), the National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service and the World Wildlife Fund (WWF) Indonesia, says the largest marine turtle in the world could soon vanish.

"If the decline continues, within 20 years it will be difficult if not impossible for the leatherback to avoid extinction," said Wibbels, who has studied marine turtles since 1980. "That means the number of turtles would be so low that the species could not make a comeback.

"The leatherback is one of the most intriguing animals in nature, and we are watching it head towards extinction in front of our eyes," added Wibbels.

Leatherback turtles can grow to six feet long and weigh as much as 2,000 pounds. They are able to dive to depths of nearly 4,000 feet and can make trans-Pacific migrations from Indonesia to the U.S. Pacific coast and back again.

While it is hard to imagine that a turtle so large and so durable can be on the verge of extinction, Ricardo Tapilatu, the research team's lead scientist who is a Ph.D. student and Fulbright Scholar in the UAB Department of Biology, points to the leatherback's trans-Pacific migration, where they face the prevalent danger of being caught and killed in fisheries.

"They can migrate more than 7,000 miles and travel through the territory of at least 20 countries, so this is a complex international problem," Tapilatu said. "It is extremely difficult to comprehensively enforce fishing regulations throughout the Pacific."

The team, along with paper co-author Peter Dutton, Ph.D., discovered thousands of nests laid during the boreal winter just a few kilometers away from the known nesting sites, but their excitement was short-lived.

"We were optimistic for this population when year round nesting was discovered in Wermon Beach, but we now have found out that nesting on that beach appears to be declining at a similar rate as Jamursba Medi," said Dutton, head of the NOAA Southwest Fisheries Science Center's Marine Turtle Genetics Program.

The study has used year-round surveys of leatherback turtle nesting areas since 2005, and it is the most extensive research on the species to date. The team identified four major problems facing leatherback turtles: nesting beach predators, such as pigs and dogs that were introduced to the island and eat the turtle eggs; rising sand temperatures that can kill the eggs or prevent the production of male hatchlings; the danger of being caught by fisheries during migrations; and harvesting of adults and eggs for food by islanders.

Tapilatu, a native of western Papua, Indonesia, has studied leatherback turtles and worked on their conservation since 2004. His efforts have been recognized by NOAA, and he will head the leatherback conservation program in Indonesia once he earns his doctorate from UAB and returns to Papua.

He has worked to educate locals and limit the harvesting of adults and eggs. His primary focus today is protecting the nesting females, eggs and hatchlings. A leatherback lays up to 10 nests each season, more than any other turtle species. Tapilatu is designing ways to optimize egg survival and hatchling production by limiting their exposure to predators and heat through an extensive beach management program.

"If we relocate the nests from the warmest portion of the beach to our egg hatcheries, and build shades for nests in other warm areas, then we will increase hatching success to 80 percent or more," said Tapilatu.

"The international effort has attempted to develop a science-based nesting beach management plan by evaluating and addressing the factors that affect hatching success such as high sand temperatures, erosion, feral pig predation and relocating nests to maximize hatchling output," said Manjula Tiwari, a researcher at NOAA's Southwest Fisheries Science Center in La Jolla, Calif.

Wibbels, who is also the Ph.D. advisor for Tapilatu, says that optimizing hatchling production is a key component to leatherback survival, especially considering the limited number of hatchlings who survive to adulthood.

"Only one hatchling out of 1,000 makes it to adulthood, so taking out an adult makes a significant difference on the population," Wibbels said. "It is essentially the same as killing 1,000 hatchlings."

The research team believes that beach management will help to decrease the annual decline in the number of leatherback nests, but protection of the leatherbacks in waters throughout the Pacific is a prerequisite for their survival and recovery. Despite their prediction for leatherback extinction, the scientists are hopeful this species could begin rebounding over the next 20 years if effective management strategies are implemented.

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The above story is reprinted from materials provided by University of Alabama at Birmingham. The original article was written by Kevin Storr.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Ricardo F. Tapilatu, Peter H. Dutton, Manjula Tiwari, Thane Wibbels, Hadi V. Ferdinandus, William G. Iwanggin, Barakhiel H. Nugroho. Long-term decline of the western Pacific leatherback,Dermochelys coriacea: a globally important sea turtle population. Ecosphere, 2013; 4 (2): art25 DOI: 10.1890/ES12-00348.1

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_environment/~3/-2zDZ55IC1Y/130226141233.htm

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?Angry Birds Toons?, Rovio?s New Cartoon Series Is Coming To A Browser Near You March 16

They're cute. They're bouncy. And they're angry. Introducing "Angry Birds Toons". Seriously. Rovio has long teased the existence of Angry Birds cartoon series but held most of the details secret. Well, all will be revealed come March 16th, when the first episode premieres.

Source: http://feedproxy.google.com/~r/Techcrunch/~3/j3hZOYqtKq0/

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