A University of Georgia researcher has invented a new technology that can inexpensively render medical linens and clothing, face masks, paper towels -- and yes, even diapers, intimate apparel and athletic wear, including smelly socks -- permanently germ-free.

The simple and inexpensive anti-microbial technology works on natural and synthetic materials. The technology can be applied during the manufacturing process or at home, and it doesn't come out in the wash. Unlike other anti-microbial technologies, repeated applications are unnecessary to maintain effectiveness.

"The spread of pathogens on textiles and plastics is a growing concern, especially in healthcare facilities and hotels, which are ideal environments for the proliferation and spread of very harmful microorganisms, but also in the home," said Jason Locklin, the inventor, who is an assistant professor of chemistry in the Franklin College of Arts and Sciences and on the Faculty of Engineering.

The anti-microbial treatment invented by Locklin, which is available for licensing from the University of Georgia Research Foundation, Inc., effectively kills a wide spectrum of bacteria, yeasts and molds that can cause disease, break down fabrics, create stains and produce odors.

According to the Centers for Disease Control and Prevention, approximately one of every 20 hospitalized patients will contract a healthcare-associated infection. Lab coats, scrub suits, uniforms, gowns, gloves and linens are known to harbor the microbes that cause patient infections.

Consumers' concern about harmful microbes has spurred the market for clothing, undergarments, footwear and home textiles with antimicrobial products. But to be practical, both commercial and consumer anti-microbial products must be inexpensive and lasting.

"Similar technologies are limited by cost of materials, use of noxious chemicals in the application or loss of effectiveness after a few washings," said Gennaro Gama, UGARF senior technology manager. "Locklin's technology uses ingeniously simple, inexpensive and scalable chemistry."

Gama said the technology is simple to apply in the manufacturing of fibers, fabrics, filters and plastics. It also can bestow antimicrobial properties on finished products, such as athletic wear and shoes, and textiles for the bedroom, bathroom and kitchen.

"The advantage of UGARF's technology over competing methods," said Gama, "is that the permanent antimicrobial can be applied to a product at any point of the manufacture-sale-use continuum. In contrast, competing technologies require blending of the antimicrobial in the manufacturing process."

"In addition," said Gama, "If for some reason the antimicrobial layer is removed from an article—through abrasion, for example—it can be reapplied by simple spraying."

Other markets for the anti-microbial technology include military apparel and gear, food packaging, plastic furniture, pool toys, medical and dental instrumentation, bandages and plastic items.

Locklin said the antimicrobial was tested against many of the pathogens common in healthcare settings, including staph, strep, E. coli, pseudomonas and acetinobacter. After just a single application, no bacterial growth was observed on the textile samples added to the culture—even after 24 hours at 37 degrees Celsius.

Moreover, in testing, the treatment remained fully active after multiple hot water laundry cycles, demonstrating the antibacterial does not leach out from the textiles even under harsh conditions. "Leaching could hinder the applicability of this technology in certain industrial segments, such as food packaging, toys, IV bags and tubing, for example," said Gama.

Thin films of the new technology also can be used to change other surface properties of both cellulose- and polymer-based materials. "It can change a material's optical properties—color, reflectance, absorbance and iridescence—and make it repel liquids, all without changing other properties of the material," said Gama.

Source: University of Georgia

But to sustain that high growth rate into the next decade, the industry will have to start tapping offshore wind resources, creating a need for wind turbines that are larger, lower-maintenance, and deliver more power with less weight.

To support research in this area, the U.S. Department of Energy has awarded $7.5 million to six projects, each aiming to develop advanced drivetrains for wind turbines up to 10 megawatts in size. Five of the projects use direct-drive, or gearless, drivetrain technology to increase reliability, and at least two use superconductivity technologies for increased efficiencies and lower weight.

Current designs can't be scaled up economically. Most of the more than 25,000 wind turbines deployed across the United States have a power rating of three megawatts or less and contain complex gearbox systems. The gearboxes match the slow speed of the turbine rotor (between 15 to 20 rotations per minute) to the 2,000 rotations per minute required by their generators. Higher speeds allow for more compact and less expensive generators, but conventional gearboxes—a complex interaction of wheels and bearings—need regular maintenance and are prone to failure, especially at higher speeds.

On land, where turbines are more accessible, gearbox maintenance issues can be tolerated. In rugged offshore environments, the cost of renting a barge and sending crews out to fix or maintain a wind-ravaged machine can be prohibitive. "A gearbox that isn't there is the most reliable gearbox," says Fort Felker, direct of the National Renewable Energy Laboratory's wind technology center.

To increase reliability and reduce maintenance costs, a number of companies—among them Enercon and Siemens of Germany, France's Alstom and China's Goldwind Global—have developed direct-drive or "gearless" drivetrains. In such a setup, the rotor shaft is attached directly to the generator, and they both turn at the same speed. But this introduces a new challenge: increased weight.

To achieve the power output of a comparable gearbox-based system, a direct-drive system must have a larger internal diameter that increases the radius—and therefore the speed—at which its magnets rotate around coils to generate current. This also means greater reliance on increasingly costly rare-earth metals used to make permanent magnets.

Kiruba Haran, manager of the electric machines lab at GE Global Research, one recipient of the DOE funding, says direct-drive systems get disproportionately heavier as their power rating increases. A four-megawatt generator might weight 85 tons, but at eight megawatts, it would approach 200 tons.

GE believes it can develop an eight-megawatt generator that weights only 50 tons by adapting the superconducting electromagnets used in magnetic resonance imaging. Unlike a permanent magnet, an electromagnet creates a magnetic field when an electric current is applied to it. When made from coils of superconducting wire, it has no electrical resistance, making it more efficient, with the caveat that it must be cooled to minus 250 °C. The approach would eliminate the need for rare-earth materials, assuming GE can lower the cost enough to make it commercially viable.

Florida-based Advanced Magnet Lab, which also received DOE funding, believes it can build a 10-megawatt generator that weighs just 70 tons. As with GE's technology, the core of the company's innovation is a superconducting direct-drive generator. The company has developed a compact coil design based on double-helix windings that can carry high currents and handle the immense magnetic forces produced in the system.

Advanced Magnet Lab president Mark Senti says the high cost of superconducting materials and of cryogenically cooling makes no sense for today's three-megawatt wind turbines. But beyond six megawatts, he argues, the systems become competitive with conventional generator designs. At 10 megawatts, "it gives you the highest power-per-weight ratio."

There's also significant room for advancement. Senti says most superconducting wiring costs $400 per meter today, but new materials made out of inexpensive magnesium and boron powders promise to lower costs substantially. With improvements in manufacturing and less expensive cooling techniques, Senti figures superconducting technology could eventually become economical for wind turbines as small as two megawatts, making it ideal for both onshore and offshore markets.

Superconductivity isn't in everyone's plans. One of the other funding recipients, Boulder Wind Power, is focused on designing a better stator—stationary coil—for direct drive systems. Instead of copper wiring wound around a heavy iron core, the company's stator is made of printed circuit boards. These lightweight components can be manufactured in high volume and assembled in modules, making them easier to repair in remote offshore locations. "With this design, you just send a couple of guys out there to remove a stator segment and literally plug in a new one," says Derek Pletch, vice president of turbine development at Boulder Wind.

NREL, meanwhile, is taking a hybrid approach by designing a medium-speed drivetrain that uses a simpler single-stage gearbox and a medium-sized generator. Felker says the approach can be easily adapted to existing designs and be picked up in the marketplace faster. Clipper Windpower and Dehlsen Associates also received funding. After six months, the DOE is expected to shortlist the designs and contribute an additional $2 million to each project for performance testing.

Source: Technology Review

A new experiment looks at the shapes of healthy and cancerous cells taken from the human cervix and has attempted to quantify the geometrical differences between them. The research, carried out at Clarkson University in Potsdam, N.Y. finds that the cancerous cells show more fractal behavior than healthy cells.

Fractal is the name used for heavily indented curves or shapes that look very similar over a variety of size scales. For example, the edge of a snowflake, when observed with a microscope, has a lacelike structure that looks the same whether at the level of a millimeter, or a tenth of a millimeter, or even a thousandth of a millimeter. The position of galaxy clusters in the sky seems to be fractal. So does the snaking geometry of streams in a river valley, or the foliage of leaves on a tree. The shape of coastlines and clouds reveals a fractal, "self-similar" geometry. Even the "drip" paintings of Jackson Pollack are fractal.

Fractal geometry apparently also appears in the human body. The pattern of heartbeats over long intervals looks fractal. How about the geometry of cells? And could the observation of fractal geometry be used to identify cancer cells?

Igor Sokolov and his Clarkson colleagues used an atomic force microscope to view cells down to the level of one nanometer, or a billionth of a meter (one-millionth of a millimeter). Just as the needle on a record player rides over the groove of a rotating vinyl record to read out the music stored on the record's surface, so the sharp needle forming the heart of an atomic force microscope rides above a sample reading out the contours of matter just below at nearly atomic resolution. 

Previous studies of cells at the microscopic level produced two-dimensional maps of the cells' surface. The new study produces not only three-dimensional surface maps of geometry. But with their atomic force microscope device the Clarkson scientists can also map properties such as the rigidity of the cells at various points on its surface or a cell's adhesion, its ability to cling to a nearby object, such as the needle probe of the atomic force microscope itself.  

The Clarkson measurements show that cancerous cells feature a consistent fractal geometry, while healthy cells show some fractal properties but in an ambiguous way. The fact that the adhesive map is fractal for cancerous cells but not for healthy cells was not known before.

Being able to differentiate clearly between healthy and cancerous cells would be important step toward a definitive diagnosis of cancer. Can a fractal measurement of cells serve as such a test for malignancy?

Sokolov believes it can. 

"The existing cytological screening tests for cervical cancer, like Pap smear, and liquid-based cytology, are effective and non-invasive, but are insufficiently accurate," said Sokolov. 

These tests determine the presence of suspicious abnormal cells with sensitivity levels ranging from 80 percent all the way down to 30 percent, for an average of 47 percent. 

The fractal criterion used in the Clarkson work was 100 percent accurate in identifying the cancerous nature of 300 cells derived from 12 human subjects, Sokolov said. He intends now to undertake a much wider test. 

"We expect that the methodology based on our finding will substantially increase the accuracy of early non-invasive detection of cervical cancer using cytological tests," Sokolov said. 

Sokolov asserts that physics-based methods, such as his atomic force microscope maps of cells, will complement or even exceed in detection ability the more traditional biochemical analysis carried out at the single cell level.

"We also plan to study how fractal behavior changes during cancerous transformation, when a normal cell turns into a fully developed malignant cell, one with a high degree of invasiveness and the ability to reproduce itself uncontrollably," Sokolov added.

Robert Austin, an expert on biological physics at Princeton University in N.J., believes it is important to learn more about the properties that make cancer cells lethal, such as their ability to metastasize, to invade new parts of the body. About the Clarkson paper, which is appearing in the journal Physical Review Letters, Austin said "Perhaps this is a step in the direction of connecting physical aspects of cancer cells with the biological reality that their proliferation and invasiveness is what makes them deadly."

Source: Inside Science News Service

With increases in asthma and other allergic diseases centered on industrialized nations, a recent hypothesis suggested that the disappearance of specific microorganisms that populate the human body due to modern hygiene practices might be to blame. Now researchers claim they have confirmed this hypothesis by proving that a certain gastric bacterium provides reliable protection against allergy-induced asthma.

The hygiene hypothesis states that modern hygiene practices and overuse of antibiotics have led to a lack of early childhood exposure to infectious agents, symbiotic microorganisms and parasites, which has suppressed the natural development of the body's immune system. Scientists from the University of Zurich and the University Medical Center of the Johannes Gutenberg University Mainz are now saying that the increase in asthma could be put down to the specific disappearance of the gastric bacterium Helicobacter pylori (H. pylori) from Western societies.

Electron micrograph of H. pylori

H. pylori is a bacterium that is resistant to gastric acid and it is estimated that it could currently infect around half of the world's population. While it can cause gastritis, gastric and duodenal ulcers, and stomach cancer under certain conditions, over 80 percent of individuals infected with the bacterium are asymptomatic. However, even if the patient doesn't show any symptoms, H. pylori is often killed off with antibiotics as a precaution.

For their study, the researchers infected mice with H. pylori bacteria at different stages of their development. They found that mice that were infected at just a few days old developed immunological tolerance to the bacterium and reacted insignificantly or not at all to strong, asthma-inducing allergens. Mice that were not infected until they had reached adulthood, however, had a much weaker defense.

"Early infection impairs the maturation of the dendritic cells and triggers the accumulation of regulatory T-cells that are crucial for the suppression of asthma," explains Anne Müller, a professor of molecular cancer research at the University of Zurich.

The researchers also found that if the regulatory T-cells were transferred from infected mice to uninfected mice, they too enjoyed effective protection against allergy-induced asthma. Additionally, mice that had been infected early lost their resistance to asthma-inducing allergens in H. pylori was killed off in them using antibiotics.

According to lung and allergy specialist Christian Taube, a senior physician at III. Medical Clinic of the Johannes Gutenberg University Mainz, the new results that are published in the Journal of Clinical Investigation confirm the hypothesis that the increase in allergic asthma in industrial nations is linked to the widespread use of antibiotics and the subsequent disappearance of micro-organisms that permanently populate the human body.

"The study of these fundamental mechanisms is extremely important for us to understand asthma and be able to develop preventative and therapeutic strategies later on," he said.

Source: GizMag

It's widely recognized that asthma rates have increased significantly since the 1960's and continue to rise. With increases in asthma and other allergic diseases centered on industrialized nations, a recent hypothesis suggested that the disappearance of specific microorganisms that populate the human body due to modern hygiene practices might be to blame. Now researchers claim they have confirmed this hypothesis by proving that a certain gastric bacterium provides reliable protection against allergy-induced asthma.

The hygiene hypothesis states that modern hygiene practices and overuse of antibiotics have led to a lack of early childhood exposure to infectious agents, symbiotic microorganisms and parasites, which has suppressed the natural development of the body's immune system. Scientists from the University of Zurich and the University Medical Center of the Johannes Gutenberg University Mainz are now saying that the increase in asthma could be put down to the specific disappearance of the gastric bacterium Helicobacter pylori (H. pylori) from Western societies.

H. pylori is a bacterium that is resistant to gastric acid and it is estimated that it could currently infect around half of the world's population. While it can cause gastritis, gastric and duodenal ulcers, and stomach cancer under certain conditions, over 80 percent of individuals infected with the bacterium are asymptomatic. However, even if the patient doesn't show any symptoms, H. pylori is often killed off with antibiotics as a precaution.

For their study, the researchers infected mice with H. pylori bacteria at different stages of their development. They found that mice that were infected at just a few days old developed immunological tolerance to the bacterium and reacted insignificantly or not at all to strong, asthma-inducing allergens. Mice that were not infected until they had reached adulthood, however, had a much weaker defense.

"Early infection impairs the maturation of the dendritic cells and triggers the accumulation of regulatory T-cells that are crucial for the suppression of asthma," explains Anne Müller, a professor of molecular cancer research at the University of Zurich.

The researchers also found that if the regulatory T-cells were transferred from infected mice to uninfected mice, they too enjoyed effective protection against allergy-induced asthma. Additionally, mice that had been infected early lost their resistance to asthma-inducing allergens in H. pylori was killed off in them using antibiotics.

According to lung and allergy specialist Christian Taube, a senior physician at III. Medical Clinic of the Johannes Gutenberg University Mainz, the new results that are published in the Journal of Clinical Investigation confirm the hypothesis that the increase in allergic asthma in industrial nations is linked to the widespread use of antibiotics and the subsequent disappearance of micro-organisms that permanently populate the human body.

"The study of these fundamental mechanisms is extremely important for us to understand asthma and be able to develop preventative and therapeutic strategies later on," he said.

Source: GizMag

Today's silicon-based microprocessor chips rely on electric currents, or moving electrons, that generate a lot of waste heat. But microprocessors employing nanometer-sized bar magnets -- like tiny refrigerator magnets -- for memory, logic and switching operations theoretically would require no moving electrons.

Such chips would dissipate only 18 millielectron volts of energy per operation at room temperature, the minimum allowed by the second law of thermodynamics and called the Landauer limit. That's 1 million times less energy per operation than consumed by today's computers.

"Today, computers run on electricity; by moving electrons around a circuit, you can process information," said Brian Lambson, a UC Berkeley graduate student in the Department of Electrical Engineering and Computer Sciences. "A magnetic computer, on the other hand, doesn't involve any moving electrons. You store and process information using magnets, and if you make these magnets really small, you can basically pack them very close together so that they interact with one another. This is how we are able to do computations, have memory and conduct all the functions of a computer."

Lambson is working with Jeffrey Bokor, UC Berkeley professor of electrical engineering and computer sciences, to develop magnetic computers.

"In principle, one could, I think, build real circuits that would operate right at the Landauer limit," said Bokor, who is a codirector of the Center for Energy Efficient Electronics Science (E3S), a Science and Technology Center founded last year with a $25 million grant from the National Science Foundation. "Even if we could get within one order of magnitude, a factor of 10, of the Landauer limit, it would represent a huge reduction in energy consumption for electronics. It would be absolutely revolutionary."

One of the center's goals is to build computers that operate at the Landauer limit.

Lambson, Bokor and UC Berkeley graduate student David Carlton published a paper about their analysis online in the journal Physical Review Letters.

Fifty years ago, Rolf Landauer used newly developed information theory to calculate the minimum energy a logical operation, such as an AND or OR operation, would dissipate given the limitation imposed by the second law of thermodynamics. (In a standard logic gate with two inputs and one output, an AND operation produces an output when it has two positive inputs, while an OR operation produces an output when one or both inputs are positive.) That law states that an irreversible process -- a logical operation or the erasure of a bit of information -- dissipates energy that cannot be recovered. In other words, the entropy of any closed system cannot decrease.

In today's transistors and microprocessors, this limit is far below other energy losses that generate heat, primarily through the electrical resistance of moving electrons. However, researchers such as Bokor are trying to develop computers that don't rely on moving electrons, and thus could approach the Landauer limit. Lambson decided to theoretically and experimentally test the limiting energy efficiency of a simple magnetic logic circuit and magnetic memory.

The nanomagnets that Bokor, Lambson and his lab use to build magnetic memory and logic devices are about 100 nanometers wide and about 200 nanometers long. Because they have the same north-south polarity as a bar magnet, the up-or-down orientation of the pole can be used to represent the 0 and 1 of binary computer memory. In addition, when multiple nanomagnets are brought together, their north and south poles interact via dipole-dipole forces to exhibit transistor behavior, allowing simple logic operations.

"The magnets themselves are the built-in memory," Lambson said. "The real challenge is getting the wires and transistors working."

Lambson showed through calculations and computer simulations that a simple memory operation -- erasing a magnetic bit, an operation often called "restore to one" -- can be conducted with an energy dissipation very close, if not identical to, the Landauer limit.

He subsequently analyzed a simple magnetic logical operation. The first successful demonstration of a logical operation using magnetic nanoparticles was achieved by researchers at the University of Notre Dame in 2006. In that case, they built a three-input majority logic gate using 16 coupled nanomagnets. Lambson calculated that a computation with such a circuit would also dissipate energy at the Landauer limit.

Because the Landauer limit is proportional to temperature, circuits cooled to low temperatures would be even more efficient.

At the moment, electrical currents are used to generate a magnetic field to erase or flip the polarity of nanomagnets, which dissipates a lot of energy. Ideally, new materials will make electrical currents unnecessary, except perhaps for relaying information from one chip to another.

"Then you can start thinking about operating these circuits at the upper efficiency limits," Lambson said.

"We are working now with collaborators to figure out a way to put that energy in without using a magnetic field, which is very hard to do efficiently," Bokor said. "A multiferroic material, for example, may be able to control magnetism directly with a voltage rather than an external magnetic field."

Other obstacles remain as well. For example, as researchers push the power consumption down, devices become more susceptible to random fluctuations from thermal effects, stray electromagnetic fields and other kinds of noise.

"The magnetic technology we are working on looks very interesting for ultra low power uses," Bokor said. "We are trying to figure out how to make it more competitive in speed, performance and reliability. We need to guarantee that it gets the right answer every single time with a very, very, very high degree of reliability."

Source: Science Daily

In the long term the technology could be used by customers to design many different products themselves -- tailor-made to their needs and preferences.

Using new digital technology the printer allows you to create your own designs on a computer and reproduce them physically in three dimensional form in chocolate.

The project is funded as part of the Research Council UK Cross-Research Council Programme -- Digital Economy and is managed by the Engineering and Physical Sciences Research Council (EPSRC) on behalf of ESRC, AHRC and MRC. It is being led by the University of Exeter in collaboration with the University of Brunel and software developer Delcam.

Chocolate printer. (Credit: Image courtesy of EPSRC)

3-D printing is a technology where a three dimensional object is created by building up successive layers of material. The technology is already used in industry to produce plastic and metal products but this is the first time the principles have been applied to chocolate.

The research has presented many challenges. Chocolate is not an easy material to work with because it requires accurate heating and cooling cycles. These variables then have to be integrated with the correct flow rates for the 3-D printing process. Researchers overcame these difficulties with the development of new temperature and heating control systems.

Research leader Dr Liang Hao, at the University of Exeter, said: "What makes this technology special is that users will be able to design and make their own products. In the long term it could be developed to help consumers custom- design many products from different materials but we've started with chocolate as it is readily available, low cost and non-hazardous. There is also no wastage as any unused or spoiled material can be eaten of course! From reproducing the shape of a child's favourite toy to a friend's face, the possibilities are endless and only limited by our creativity."

A consumer- friendly interface to design the chocolate objects is also in development. Researchers hope that an online retail business will host a website for users to upload their chocolate designs for 3-D printing and delivery.

Designs need not start from scratch, the web- based utility will also allow users to see designs created by others to modify for their own use.

Dr Hao added: "In future this kind of technology will allow people to produce and design many other products such as jewellery or household goods. Eventually we may see many mass produced products replaced by unique designs created by the customer."

EPSRC Chief Executive Professor Dave Delpy said: "This is an imaginative application of two developing technologies and a good example of how creative research can be applied to create new manufacturing and retail ideas. By combining developments in engineering with the commercial potential of the digital economy we can see a glimpse into the future of new markets -- creating new jobs and, in this case, sweet business opportunities."

Source: ScienceDaily

His experiments using the fluorinated polymer as a surface coating for pots and pans helped usher in a revolution in non-stick cookware. Today, NYU-Poly Assistant Professor of Chemical and Biological Sciences Jin Montclare is taking the research theme in a new direction, investigating fluorinated proteins -- a unique class of proteins that may have a wide range of applications from industrial detergents to medical therapeutics.

In a paper published in the current issue of ChemBioChem, Montclare and Peter Baker, who just received his doctoral degree from NYU-Poly, detail their success in creating proteins that are considerably more stable and less prone to denaturation than their natural counterparts. These qualities enable them to retain both their structure and function under high temperatures in which other proteins would simply break down.

Fluorinated amino acids (p-fluorophenylalnine highlighted in the interface) help stabilize Teflon-like proteins against heat inactivation, allowing them to function more robustly, even at elevated temperatures.

Inspired by the ability of fluorinated polymers like Teflon to stabilize surfaces, Montclare and Baker set their sights on developing a process that would allow them to reinforce the interface of proteins, rendering them more resistant to degradation.

“One of the main challenges of proteins—whether they’re in the body or in the lab—is that they are naturally created to function under specific conditions, and to break down under others,” Montclare explained. “A stable protein that was still active and functional under a variety of conditions would open up an extraordinary range of potential for scientists and product developers.”

Through a trick of genetic engineering, the scientists were able to coax a strain of bacteria into taking up amino acids—the building blocks of protein—that were chemically altered by the addition of fluorine. “Nature doesn’t make fluorinated amino acids, but these experiments show that we can create them,” said Montclare. The result was a "fluorinated" protein that can withstand temperatures up to 140 degrees Fahrenheit with no compromise in activity or function.

Next up for Montclare and Baker are experiments to test the limits of their success in creating fluorinated or Teflon-like proteins. They’re hoping that this type of effect can be achieved with a wide range of proteins, especially those used in medicine including some therapeutic cancer drugs. The stable proteins may also some day act as prophylactics to combat exposure to neurotoxic agents (including warfare agents)–something that is of interest to the Department of Defense. The scientists hope to improve the proteins’durability and decrease the need for precise storage conditions, which often include refrigeration to prevent breakdown.

Source: PhysOrg

The research adds an important link to discoveries that have enabled scientists to gain a deeper understanding of how cells translate genetic information into the proteins and processes of life. The findings, published in the July 3 advance online issue of the journal Nature, were reported by a research team led by Yuichiro Takagi, Ph.D., assistant professor of biochemistry and molecular biology at Indiana University School of Medicine.

The fundamental operations of all cells are controlled by the genetic information – the genes –stored in each cell's DNA, a long double-stranded chain. Information copied from sections of the DNA – through a process called transcription – leads to synthesis of messenger RNA, eventually enabling the production of proteins necessary for cellular function. Transcription is undertaken by the enzyme called RNA polymerase II.

As cellular operations proceed, signals are sent to the DNA asking that some genes be activated and others be shut down. The Mediator transcription regulator accepts and interprets those instructions, telling RNA polymerase II where and when to begin the transcription process.

Mediator is a gigantic molecular machine composed of 25 proteins organized into three modules known as the head, the middle, and the tail. Using X-ray crystallography, the Takagi team was able to describe in detail the structure of the Mediator Head module, the most important for interactions with RNA polymerase II.

"It's turned out to be extremely novel, revealing how a molecular machine is built from multiple proteins," said Takagi.

"As a molecular machine, the Mediator head module needs to have elements of both stability and flexibility in order to accommodate numerous interactions. A portion of the head we named the neck domain provides the stability by arranging the five proteins in a polymer-like structure," he said.

"We call it the alpha helical bundle," said Dr. Takagi. "People have seen structures of alpha helical bundles before but not coming from five different proteins."

"This is a completely noble structure," he said.

One immediate benefit of the research will be to provide detailed mapping of previously known mutations that affect the regulation of the transcription process, he said.

The ability to solve such complex structures will be important because multi-protein complexes such as Mediator will most likely become a new generation of drug targets for treatment of disease, he said.

Previously, the structure of RNA polymerase II was determined by Roger Kornberg of Stanford University, with whom Dr. Takagi worked prior to coming to IU School of Medicine. Kornberg received the Nobel Prize in 2006 for his discoveries. The researchers who described the structure of the ribosome, the protein production machine, were awarded the Nobel Prize in 2009. The structure of the entire Mediator has yet to be described, and thus remains the one of grand challenges in structure biology. Dr. Takagi's work on the Mediator head module structure represents a major step towards a structure determination of the entire Mediator.

Source: PhysOrg

Now, the Whitesides group at Harvard University has developed a force sensor for a microelectromechanical system (MEMS) using paper as the structural material [Whitesides et al., Lab Chip(2011) doi: 10.1039/c1lc20161a].

MEMS devices are becoming increasingly common in research, in industrial settings and in medical diagnostics. Several companies have now developed MEMS for a wide range of applications: digital micromirror devices (DMD, Texas Instruments), accelerometers for firing vehicle airbags (Analog Devices and Motorola), and pressure/?ow sensors for industrial uses (Honeywell). However, while such devices are based on semiconductor materials, such as silicon, they will remain expensive and require complex manufacturing facilities and clean rooms for their construction.

Photograph of an array of four devices. Image courtesy of Xinyu Liu, Whitesides. Reproduced from Lab Chip (2011) doi: 10.1039/c1lc20161a by permission of The Royal Society of Chemistry.

Whitesides and colleagues hope to circumvent such obstacles by finding inexpensive alternatives to silicon and its ilk and precluding the need for complex and costly fabrication processes. As such, they have now developed a prototypical MEMS device; a paper-based piezoresistive force sensor, demonstrating that a readily available and easy to prepare material can be used to build useful devices, albeit with perhaps poorer performance than conventional MEMS. The same approach has also been used to develop a paper-based weighing balance.

The group emphasizes that the force sensor is simple to construct, taking less than an hour with no special facilities or equipment; a paper cutter and painting knife are all that are needed. Material costs for each device are of the order of a few cents. When asked about the novelty and utility of this work, Whitesides remarked to Materials Today that, "Sometimes things that obviously can't work have a mind of their own and work anyway."

The team has shown that the force sensor can measure the properties of a soft material with moderate, but useful, performance compared to conventional MEMS, giving a resolution of 120 micronewtons and a 16 millinewton measurement range. The paper-based balance can measure up to 15 grams and has a resolution of 0.39 grams.

These low-cost, portable and disposable paper-based MEMS devices could be used as single-use sensors in analytical applications, for instance in the mechanical characterization of tissues in medical diagnostics and in food viscosity measurements. The researchers add that in contrast to silicon-based MEMS, a paper-based device might be too sensitive to high temperatures, atmospheric components , such as water vapor, ozone, peroxides, etc. However, in some contexts such sensitivities might also be exploited for other applications of the device, such as humidity sensors or an ad hoc chemical detector for emergencies.

Source: Materials Today