MIT chemical engineer Paula Hammond lends her nanotechnology expertise to farmers in Africa.

(NanoRealm) - Cassava is a tropical root vegetable and staple crop for millions of people in sub-Saharan Africa. However, it’s tricky to handle: Once the root is removed from the ground, it spoils within one to three days, so farmers must get it to processing centers as soon as possible after harvesting it. If they don’t, the crop goes to waste.
A simple way to prolong cassava’s shelf life could help farmers avoid that waste and sell their crop beyond their local region. Paula Hammond, MIT professor of chemical engineering, and other scientists are now working on an innovative way to help them do that, using nanotechnology — technology that controls material at a molecular or atomic scale. Their idea is to design a plastic storage bag lined with nanoparticles that would react with oxygen, preventing the roots’ oxygen-induced rotting.

“That would enable farmers to harvest and store and process at times convenient to them,” says Hammond, who traveled to Kenya and Ghana last summer with an international group of scientists to meet with farmers and come up with new ways to improve agricultural efficiency.

It may seem odd to send Hammond, a chemical engineer who focuses on nanotechnology, into rural Africa to help farmers. But that’s exactly the point, says Todd Barker, a partner for the Meridian Institute, which organized the trip with funding from the Bill & Melinda Gates Foundation.

Organizers were looking for scientists who specialize in fields not traditionally involved in international development. And they wanted people who knew little or nothing about agriculture, says Barker. “We wanted to get them to look at these particular problems in Africa with a fresh set of eyes.”

‘An important problem’

After the Meridian Institute identified three agricultural chains where farmers needed help — cassava, dairy and maize (corn), Barker enlisted Jeffrey Carbeck PhD ’96, a chemical engineer and entrepreneur, to identify scientists who would fit in with the mission. “I was looking for people who had a deep technical background but had shown they could apply it in multiple areas,” says Carbeck, who knew Hammond from their graduate school days at MIT.

Carbeck thought that Hammond, an expert in designing polymers for drug delivery, sensors and energy, would fit perfectly. Hammond, in turn, was intrigued by the idea. “It sounded like such an important problem, and I had never been to Africa. This was a chance to see it from a very unique perspective,” she says.

Equipped with Land Rovers and digital video cameras, the group of a dozen scientists from around the world traveled to farms throughout the two African nations, talking with farmers to find out the biggest obstacles they face.

For Hammond, the trip was enlightening. “These working families have very immediate problems and have neither the resources, nor perhaps the voice, to express them to groups of elite scientists, and that’s what this allowed them to do,” she says. “These are really exciting problems outside the realm of what we might normally encounter in academia.”

The team found that dairy farmers have a similar problem to cassava farmers — getting their milk to processing centers before it spoils. Most farms don’t have their own refrigeration facilities, so the farmers have to carry their milk in plastic jugs, usually on foot or bicycle, to the nearest cooling center.

If the cooling centers are far from the farm, the farmers might make only one trip a day, so any milk produced after that trip is in danger of spoiling before the next day’s trip. Milk that goes bad is rejected at the center and dumped out.

To avoid that waste, Hammond and other scientists in the group came up with the idea to design a milk container with a nanopatterned, antimicrobial coating that would preserve milk longer than a plain plastic jug.

The African dairy farmers are also interested in a way to easily test their cows to see if they’re pregnant or in heat. Cows must be bred and produce calves in order to produce milk, but if a cow runs dry, it’s difficult to tell whether it’s due to lack of pregnancy or a common udder infection known as mastitis.

There is no simple test for cow pregnancy as there is for humans, but scientists who went on the trip came up with the idea to adapt existing nanopatterned paper sensors to detect bovine pregnancy.

The Gates Foundation originally planned to allocate funding for two or three ideas that came out of the trip, but there were so many (more than 200, later consolidated into 22 concepts), that the foundation is encouraging the scientists to pursue as many as possible. The Meridian Institute will initially focus on diagnostic tools for mastitis, the new milk container, tick-borne disease and other livestock diseases, safety tests for milk, a modified plastic tank for maize storage, and a new way to dry cassava.

The Meridian Institute is now working on starting up a foundation that would serve as an “incubator” to help develop, test and bring these ideas to commercialization, according to Barker. “The major challenge now is to make sure the ideas that came out of the trip reach the farmers in Africa,” he says.

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In the World is a column that explores the ways members of the MIT community are developing technology — from the appropriately simple to the cutting edge — to help meet the needs of communities around the planet, especially those in the developing world.

Source: MIT News (http://web.mit.edu/newsoffice/2010/nanotech-farm-0312.html)

(NanoRealm) - Scientists in Manchester have found a clean and green way of making tiny magnets for high tech gadgets - using natural bacteria that have been around for millions of years.

The work by a team of geomicrobiologists from the University of Manchester paves the way for nanometer-size magnets - used in mobile phones and recording devices - to be made without the usual nasty chemicals and energy intensive methods.

Researchers studied iron-reducing bacteria that occur naturally in soils and sediments and found they can be used to create iron oxide nanoparticles with magnetic properties similar to those created through complex chemical processes.

Working with colleagues in Birmingham and Cardiff, the Manchester researchers also found a way of exercisising precise control over the size and magnetic strength of nanomagnets produced.
The high-tech particle accelerators at the Advanced Light Source at the famous Berkeley Labs near San Francisco, and the UK’s Diamond Light Source in Oxford at Harwell were used to verify findings.

Researchers added cobalt, manganese or nickel to the basic iron-based energy source used by bacteria, which resulted in the production of tiny magnets containing these elements. This greatly enhanced their useful magnetic properties.

Aside from being used in the latest gadgets, nanomagnets also have the potential to be used in drug delivery systems and cancer therapies to carefully focus and target the release of chemicals into the body.

Metal-reducing bacteria live in environments deficient in oxygen and react with oxidised metals to produce natural magnets in the ground beneath our feet.
And now the research team has developed a way of harnessing pure strains of these bacteria - which are in plentiful supply and reproduce quickly - to produce large quantities of nanomagnets at an ambient temperature.

This compares favourably to the extreme temperatures - as high as 1000 degrees Celsius - needed to create nanomagnets using current methods.
Prof Richard Patrick, Professor of Earth Science, said: “This is exciting work that raises the exciting prospect of a biologically friendly, energy-efficient method of producing nanomagnets tailored for different uses.”

A paper - ‘Harnessing the extracellular bacterial production of nanoscale cobalt ferrite with exploitable magnetic properties’ - outlining the research was published recently in the journal ACS Nano.

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(NanoRealm) - When nanoparticles from consumer products leach into the ocean, they may harm oysters and mussels.

Nanoparticles May Harm Ocean Living Creatures

Manufactured nanomaterials can be found in such diverse applications as electronics, cosmetics, paints, and even medicines, but their effects on the environment remain largely unknown. In a new laboratory study, scientists have found that saltwater oysters and mussels take up and retain significant amounts of manufactured nanoparticles from seawater in clumps of so-called “marine snow.”

“Nanomaterials are being used in increasing amounts, and it’s likely they’re being released in increasing amounts into the environment, including the ocean,” says Evan Ward, professor of marine sciences at UConn’s Avery Point campus. “As we develop these technologies, we need to be cautious, we need to know where the particles are going, and we need to know how they affect marine organisms.”

Nanoparticles are tiny versions of common materials that have a diameter of less than 100 nanometers, or about four millionths of an inch. Their tininess gives them properties that normal-sized particles don’t have: for example, their large surface area for their size makes them stronger, lighter, and more reflective, making them ideal for reinforcing metals, increasing the SPF in your sunscreen, and producing paint that improves your home’s energy efficiency.
Some scientists, however, are concerned that these very properties could also make manufactured nanoparticles dangerous. When products break down in landfills, nanoparticles can wash away into soils, waterways, and the ocean, potentially creating hazards to animals and plants.
“Some materials that one would assume are safe can in fact cause damage to cells in their ‘nano’ form,” Ward says.

Ward studies the environmental physiology of oysters, mussels, and their relatives, which use their gills as specialized filters to take up food from ocean water. Although nanoparticles themselves are too small to be captured in large amounts, Ward’s study focused on how the bivalves’ feeding ecology affected their rate of uptake.

“In our study, we took into account how nanoparticles are likely to be delivered to the animals in the natural environment,” he says. “We asked, ‘What’s the setting in which they will be exposed to these particles?’”

Materials rarely exist as individual particles in the ocean, says Ward; instead, ocean currents bind up particles and sticky organic matter into aggregates that scientists call “marine snow.” These aggregates then sink to the bottom, where filter feeders like bivalves ingest them.

In their paper, published in Marine Environmental Research, Ward and coauthor Dustin Kach, a former UConn graduate student, used natural seawater to produce marine snow that contained fluorescently labeled polystyrene nanoparticles. They then exposed oysters and mussels collected from the Long Island Sound to this snow-filled seawater.

The researchers found that nanoparticles were taken up in much higher amounts when the bivalves were exposed to marine snow. But they also found that when filtered from marine snow, nanoparticles remained in the bivalves’ bodies for a much longer time than would be expected for non-nutritive materials: up to three days.

Ward suspects that the particles are being treated as food by the animals, and are being taken up into their digestive cells. This could be particularly dangerous, he says, since small nanoparticles can circumvent living cells’ natural defenses.

“Because of their high surface area, manufactured nanoparticles can strip off electrons from other compounds and create free radicals,” he says. “Particles like these can cause havoc in cells.”
Ward sees his work as a first step in understanding the potential issues associated with manufactured nanoparticles. He emphasizes that further work is needed to determine the amounts of manufactured nanoparticles in seawater and their levels of toxicity to living things.

“Right now there are few techniques to identify manufactured nanomaterials in the natural environment because they’re so darn small,” he says. “With these studies, we hope to demonstrate potential problems to keep in step with the use of nanomaterials. Then when techniques are available to sample them in the wild, we’ll be prepared to say whether or not we should be worried.”

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More information: http://www.elsevier.com/wps/find/journaldescription.cws_home/405865/description#description
Provided by University of Connecticut (web)

Source: http://www.physorg.com/news186058984.html

(NanoRealm) - Researchers move one step closer to nature with the development of polymers and directional adhesion that follow the workings of a gecko's foot

Nanotechnology has not only brought nature and engineering closer together; it has encouraged collaboration among researchers of different disciplines. In one such collaboration, two researchers drew on the extraordinary stickiness of a gecko's foot to develop a synthetic adhesive to help robots scale walls.

NSF-funded researchers Mark Cutkosky, an engineer at Stanford University, and Kellar Autumn, a biologist at Lewis and Clark College, have collaborated to develop a gecko-like synthetic adhesive that functions like real gecko bristles for climbing applications. The team discovered the fundamental physics principles underlying gecko adhesion, which enabled the invention of an adhesive nanostructure.

The Tokay gecko, one of the largest and heaviest geckos, served as inspiration.

"The challenge was simply to get robots to go where robots have never been able to go before, like up walls of buildings," said Cutkosky. "If robots can climb vertical surfaces, then they can do inspection of buildings and bridges and other hard- to-reach places."

Cutkosky received a four-year, $1 million National Science Foundation research grant that funded the development of the first gecko-like synthetic adhesive (GSA) that works like real gecko bristles. Autumn received two NSF grants for continued research on gecko adhesion. Cutkosky's team collaborated with Kellar Autumn and his gecko lab to determine whether a synthetic adhesive could be applied to robots.

"The collaboration with Mark's group has been incredibly productive. Based on micro-force measurements, we hypothesized that a coupling of shear force and adhesion was responsible for control of the geckos' attachment system," said Autumn.

A gecko's foot possesses a sophisticated adhesion system that uses van der Waals forces, which are the basic molecular attraction that exists between molecules. Van der Waals forces allow geckos to climb and hang on a smooth and vertical surfaces using one toe.

Cutkosky and his team have been designing bio-inspired robots which use van der Waals forces. Their most recent design is stickybot, a robot that has gecko-like pads, which allows it to scale walls and buildings.

Bio-inspired design on a nano scale

The intricate work of nature occurs on a tiny scale, below the limits of our vision. Beneath the surface of a gecko's foot is a three-level hierarchy of structures. The first level is made up of lamellae, which are a series of structures that look like flaps under a microscope. Then, the lamellae are divided into smaller structures called seate which are thinner than a human hair. Finally, the seate branch into tiny little ends called spatulae, which are only a couple of hundred nanometers in size.

"So what happens is that the gecko is able to conform to surfaces ranging from tens or hundreds of nanometers all the way up to centimeters," said Cutkosky. "It is very cool; it is sort of the poster child for complex hierarchical geometry, almost fractal in its nature."

The structures that compose the different levels in the hierarchy have a similar behavior at multiple length scales.

The gecko's toe structures are only adhesive when loaded in a particular direction and the gecko can control adhesion by aligning its microstructures and making intimate contact with the surface. Stickybot follows the same principles as a gecko, but needs to adjust the orientation of its feet as it climbs. This is to ensure that the toes are always loaded in the proper direction for adhesion.

Cutkosky and Autumn have built similar synthetic structures that follow the design of a gecko's foot. At present, they have created a two layer hierarchy of polymers with directional adhesion. This is good enough for stickybot to use to scale walls; however there is always room for improvement.

"It comes down to how much adhesion you are getting per unit area. The gecko can easily support its weight on one toe. In fact, it has lots to spare. Without the latest and greatest adhesives, I think stickybot can barely support its weight on one toe. We are nowhere near the gecko. Basically, it comes down to the weight of the robot and how many pascals of adhesion you can get from your material," said Cutkosky.



The pascal is a measurement of force per unit area which allows researchers, like Cutkosky, to determine how much stress the synthetic adhesion can tolerate. This helps gauge how the adhesive is developed and how it can be changed in the future.

The future of stickybot

Stickybot employs three main principles to climb smooth surfaces: hierarchical compliance to conform to levels from micrometers to centimeters, directional adhesion to smoothly engage and disengage from a surface, and force control to control frictional forces in the feet. Though stickybot can climb on vertical and smooth surfaces, Cutkosky hopes to develop a robot capable of climbing a wide variety of surfaces.

"We are continuing to try and improve the dry adhesive itself, but independent from that; we are working on a new stickybot. Making the ankles of the robot rotate is probably number one, but we also want to do more sensing and control. Right now stickybot doesn't have many sensors, so if it's climbing and starting to get into trouble, it doesn't know that and may fall," said Cutkosky.


Cutkosky and Autumn's research and collaboration have shown how materials science is attempting to follow nature.

"Nature has a huge advantage it can grow and differentiate cell by cell. Whereas, when we manufacture things we're always using processes that work top-down and so every layer is difficult and expensive for us," said Cutkosky.

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Sources:

• National Science Foundation
  
• Stanford
  
• Gecko Lab Lewis and Clark