Scientists Produce World's First Magnetic Soap

                                         The liquid crystal progression of each surfactant was investigated by the solvent penetration method (i.e. phase cut). A small amount of surfactant was placed on a microscope slide under a coverslip. The slide was mounted on the cover slide and heated until the sample was fluid and completely isotropic. After slow cooling (1.0 °C min-1) to 25 °C, a drop of water was added to the edge of the coverslip. As the water penetrated the surfactant, a concentration gradient was established, from water at one side to pure surfactant at the other, enabling the entire range of mesophases to be observed in the field of view. (Credit: Image courtesy of Institut Laue-Langevin (ILL))                                  ScienceDaily  — Scientists from Bristol University have developed a soap, composed of iron rich salts dissolved in water, that responds to a magnetic field when placed in solution. The soap’s magnetic properties were shown with neutrons at the Institut Laue-Langevin to result from tiny iron-rich clumps that sit within the watery solution. The generation of this property in a fully functional soap could calm concerns over the use of soaps in oil-spill clean ups and revolutionise industrial cleaning products.

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Scientists have long been searching for a way to control soaps (or surfactants as they are known in industry) once they are in solution to increase their ability to dissolve oils in water and then remove them from a system. The team at Bristol University have previously worked on soaps sensitive to light, carbon dioxide or changes in pH, temperature or pressure. Their latest breakthrough, reported in Angewandte Chemie, is the world’s first soap sensitive to a magnetic field.
Ionic liquid surfactants, composed mostly of water with some transition metal complexes (heavy metals like iron bound to halides such as bromine or chlorine) have been suggested as potentially controllable by magnets for some time, but it had always been assumed that their metallic centres were too isolated within the solution, preventing the long-range interactions required to be magnetically active.
The team at Bristol, lead by Professor Julian Eastoe produced their magnetic soap by dissolving iron in a range of inert surfactant materials composed of chloride and bromide ions, very similar to those found in everyday mouthwash or fabric conditioner. The addition of the iron creates metallic centres within the soap particles.
To test its properties, the team introduced a magnet to a test tube containing their new soap lying beneath a less dense organic solution. When the magnet was introduced the iron-rich soap overcame both gravity and surface tension between the water and oil, to levitate through the organic solvent and reach the source of the magnetic energy, proving its magnetic properties.
Once the surfactant was developed and shown to be magnetic, Prof Eastoe’s team took it to the Institut Laue-Langevin, the world’s flagship centre for neutron science, and home to the world’s most intense neutron source, to investigate the science behind its remarkable property.
When surfactants are added to water they are known to form tiny clumps (particles called micelles). Scientists at ILL used a technique called “small angle neutron scattering (SANS)” to confirm that it was this clumping of the iron-rich surfactant that brought about its magnetic properties.
Dr Isabelle Grillo, responsible of the Chemistry Laboratories at ILL: “The particles of surfactant in solution are small and thus difficult to see using light but are easily revealed by SANS which we use to investigate the structure and behaviour of all types of materials with typical sizes ranging from the nanometer to the tenth of micrometer.”
The potential applications of magnetic surfactants are huge. Their responsiveness to external stimuli allows a range of properties, such as their electrical conductivity, melting point, the size and shape of aggregates and how readily its dissolves in water to be altered by a simple magnetic on and off switch. Traditionally these factors, which are key to the effective application of soaps in a variety of industrial settings, could only be controlled by adding an electric charge or changing the pH, temperature or pressure of the system, all changes that irreversibly alter the system composition and cost money to remediate.
Its magnetic properties also makes it easier to round up and remove from a system once it has been added, suggesting further applications in environmental clean ups and water treatment. Scientific experiments which require precise control of liquid droplets could also be made easier with the addition of this surfactant and a magnetic field.
Professor Julian Eastoe, University of Bristol: “As most magnets are metals, from a purely scientific point of view these ionic liquid surfactants are highly unusual, making them a particularly interesting discovery. From a commercial point of view, though these exact liquids aren’t yet ready to appear in any household product, by proving that magnetic soaps can be developed, future work can reproduce the same phenomenon in more commercially viable liquids for a range of applications from water treatment to industrial cleaning products.”
Peter Dowding an industrial chemist, not involved in the research: “Any systems which act only when responding to an outside stimulus that has no effect on its composition is a major breakthrough as you can create products which only work when they are needed to. Also the ability to remove the surfactant after it has been added widens the potential applications to environmentally sensitive areas like oil spill clean ups where in the past concerns have been raised.”

Scientists keep their eyes on peripheral vision

(Medical Xpress) -- Two USC scientists are bringing peripheral vision into focus, showing that the way the brain sharpens its attention while the eyes are in motion leads to false assumptions about how objects should look.
The eye’s photoreceptors — the cells that detect light — are clustered at the center of the field of vision, leaving the periphery like a low-resolution camera. USC Dornsife neuroscientist Bosco S. Tjan and USC graduate student Anirvan S. Nandy theorized that peripheral vision is hindered by the visual experience formed in the brain during eye movements.
Their paper was published online on Jan. 8 in Nature Neuroscience.
According to the researchers, a single neural signal directs the eyes to look at an object of interest in the periphery and causes the brain to start paying attention to that object. Unless they are tracking an object — such as a police officer’s penlight during a sobriety test — human eyes do not tend to move in fluid motions. Instead, they jump from one point of focus to another in a jerky fashion called “saccadic” eye movement.
Those movements bring an object into the center of the field of vision. The brain actually starts paying attention to that object — “turning on” its ability to learn about it — shortly before the eyes move and lock on to it.
The researchers said this makes the version of the visual world that the brain learns from the periphery appear smeared.
“Parts of the brain that process peripheral vision assume these smears were typical of the physical world and make corresponding perceptual errors that cannot be explained by merely seeing the world in low resolution,” said Tjan, associate professor of psychology.
Vision is based, in part, on assumptions made by the brain. For example, if you look at a coffee mug, your brain sees one side of it and assumes that the rest is completely round — when in fact the back side that you do not see could be almost any shape at all, to a certain point.
“For the brain to see things, generally speaking, it has to make assumptions about the world,” Tjan said.
(Mis)guided by the peripheral vision’s smeared version of the world, the brain would have a hard time recognizing objects in the periphery and be more prone to error. Tjan and Nandy’s theory explained a wealth of empirical data on peripheral vision gathered in the last few decades.
Tjan said he hopes their work will help inform therapy for patients suffering from diseases like macular degeneration, in which damage to the retina costs patients sight at the center of the field of vision.
Macular degeneration is, for the moment, irreversible. Patients with macular degeneration are retaught how to see by focusing their attention outside the center of their field of vision — a difficult task, given the poor quality of the image with which they are left.

“At least for now, the best we can hope for is to train a patent to use [his or her] periphery. But to do that, we need to know why the periphery is so much worse,” Tjan said.

The research was supported by the National Eye Institute of the National Institutes of Health.
Provided by USC College
"Scientists keep their eyes on peripheral vision." January 20th, 2012. http://medicalxpress.com/news/2012-01-scientists-eyes-peripheral-vision.html

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Biochip measures glucose in saliva, not blood

  by Biomechanism 

Engineers at Brown University have designed a biological device that can measure glucose concentrations in human saliva. The technique could eliminate the need for diabetics to draw blood to check their glucose levels. The biochip uses plasmonic interferometers and could be used to measure a range of biological and environmental substances. Results are published in Nano Letters. 

Each plasmonic interferometer – thousands of them per square millimeter – consists of a slit flanked by two grooves etched in a silver metal film. The schematic shows glucose molecules “dancing” on the sensor surface illuminated by light with different colors. Changes in light intensity transmitted through the slit of each plasmonic interferometer yield information about the concentration of glucose molecules in solution. Credit: Domenico Pacifici

For the 26 million Americans with diabetes, drawing blood is the most prevalent way to check glucose levels. It is invasive and at least minimally painful. Researchers at Brown University are working on a new sensor that can check blood sugar levels by measuring glucose concentrations in saliva instead.
The technique takes advantage of a convergence of nanotechnology and surface plasmonics, which explores the interaction of electrons and photons (light). The engineers at Brown etched thousands of plasmonic interferometers onto a fingernail-size biochip and measured the concentration of glucose molecules in water on the chip. Their results showed that the specially designed biochip could detect glucose levels similar to the levels found in human saliva. Glucose in human saliva is typically about 100 times less concentrated than in the blood.

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“This is proof of concept that plasmonic interferometers can be used to detect molecules in low concentrations, using a footprint that is ten times smaller than a human hair,” said Domenico Pacifici, assistant professor of engineering and lead author of the paper published in Nano Letters, a journal of the American Chemical Society.
The technique can be used to detect other chemicals or substances, from anthrax to biological compounds, Pacifici said, “and to detect them all at once, in parallel, using the same chip.”
To create the sensor, the researchers carved a slit about 100 nanometers wide and etched two 200 nanometer-wide grooves on either side of the slit. The slit captures incoming photons and confines them. The grooves, meanwhile, scatter the incoming photons, which interact with the free electrons bounding around on the sensor’s metal surface. Those free electron-photon interactions create a surface plasmon polariton, a special wave with a wavelength that is narrower than a photon in free space. These surface plasmon waves move along the sensor’s surface until they encounter the photons in the slit, much like two ocean waves coming from different directions and colliding with each other.
This “interference” between the two waves determines maxima and minima in the light intensity transmitted through the slit. The presence of an analyte (the chemical being measured) on the sensor surface generates a change in the relative phase difference between the two surface plasmon waves, which in turns causes a change in light intensity, measured by the researchers in real time.
“The slit is acting as a mixer for the three beams — the incident light and the surface plasmon waves,” Pacifici said.
The engineers learned they could vary the phase shift for an interferometer by changing the distance between the grooves and the slit, meaning they could tune the interference generated by the waves. The researchers could tune the thousands of interferometers to establish baselines, which could then be used to accurately measure concentrations of glucose in water as low as 0.36 milligrams per deciliter.
“It could be possible to use these biochips to carry out the screening of multiple biomarkers for individual patients, all at once and in parallel, with unprecedented sensitivity,” Pacifici said.
The engineers next plan to build sensors tailored for glucose and for other substances to further test the devices. “The proposed approach will enable very high throughput detection of environmentally and biologically relevant analytes in an extremely compact design. We can do it with a sensitivity that rivals modern technologies,” Pacifici said.
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Tayhas Palmore, professor of engineering, is a contributing author on the paper. Graduate students Jing Feng (engineering) and Vince Siu (biology), who designed the microfluidic channels and carried out the experiments, are listed as the first two authors on the paper. Other authors include Brown engineering graduate student Steve Rhieu and undergraduates Vihang Mehta, Alec Roelke.
The National Science Foundation and Brown (through a Richard B. Salomon Faculty Research Award) funded the research.