Sunday, May 15, 2011

Sugar Flushes Out Hidden Microbes

Used to be that sick kids got lollypops after a visit with the doctor. But in some cases candy can be more than a reward—it can be part of the therapy. Because scientists have found that, in battling chronic infections, sugar can boost the effectiveness of antibiotics. The study appears in the journal Nature. [James Collins, Mark Brynildsen and Kyle Allison, Metabolite-enabled eradication of bacterial persisters by aminoglycosides]

Chronic infections can be caused by persistent bacteria that have learned how to lay low until all the antibiotics are gone. They’re not exactly antibiotic resistant, so they don’t have any special drug-destroying mutations. They just power down, metabolically speaking, and then wait until the coast is clear (of antibiotics) to come back to life. Which is why the poor patient just can’t seem to clear the infection.

To eliminate such stealthy bacteria, scientists at Boston University searched for a way to jump start the bugs’ metabolism. And they found that sugar is just what the doctor ordered. Administering sugar along with an antibiotic called gentamicin cured mice with chronic urinary tract infections, and kept the bacteria from spreading to their kidneys.

So a spoonful of sugar does more than make the medicine go down. It helps the medicine take the microbes down.

—Karen Hopkin

[The above text is an exact transcript of this podcast]

View the original article here

Lasers take the lead in auto manufacturing

Conserving energy is a top priority for auto manufacturers today. Laser technology can help. Lasers can be used to process thin light-weight components made of fiber-composite materials, as well as to manufacture more efficient engines and more powerful batteries. At the Laser 2011 trade fair from 23 -- 26 May, Fraunhofer scientists will be presenting new production technologies.

The era of gas guzzlers that clatter through streets and pollute the air is over. Cars rolling off the assembly line today are cleaner, quieter and -- in terms of their performance weight -- more efficient than ever before. Nevertheless, development continues. Ever-stricter environmental regulations and steadily rising fuel costs are increasing the demand for cars that further reduce their impact on the environment. But customer demands are often tough for manufacturers to meet: car bodies should be safe yet light-weight and engines durable yet efficient. Year after year, new models must be developed and built that can claim to be better, more efficient, and more intelligent than the last.

The race against time and competitors places high demands on manufacturers and their suppliers. Lasers can help them win the race. Resistant to wear and universally applicable, laser light is an ideal tool in the manufacture of vehicles. Lasers can be used to join, drill, structure, cut or shape any kind of material. Surfaces can be engineered for motors and drive trains that create less friction and use less fuel. Lasers are not only a decisive key towards faster, more efficient and economical production, but also towards energy-saving vehicles. At Laser 2011, Fraunhofer scientists will demonstrate how we can use lasers to save time, money and energy.

A weight-loss program in automotive manufacturing

Extra pounds cost energy. They have to be accelerated and slowed down every time you drive -- over the entire lifespan of the car. To reduce weight, manufacturers are increasingly turning to the use of fiber-reinforced plastics, which are 30 to 50 percent lighter than metal. The disadvantage, however, is that these new materials are difficult to process. Fiber-reinforced plastics are brittle, meaning cutting and drilling tools are quickly worn out and the conventional assembly techniques used for metal components are often not appropriate. "Lasers represent an ideal alternative here," explains Dr. Arnold Gillner of the Fraunhofer Institute for Laser Technology ILT in Aachen. "Lasers can cut fiber-reinforced plastics without wear and can join them too. With the appropriate lasers, we can cut and ablate components with minimal thermal side-effects. Lasers can also be used for welding light-weight components -- a viable alternative to conventional bonding technology. We can even join fiber-reinforced plastics to metals with laser welding. The laser roughens the metal surface, while the plastic, briefly-heated, penetrates the pores of the metal and hardens. The results are very stable."

Weight reduction can also be achieved with high-strength metallic materials. These, however, are difficult to process. "Joining combinations of various materials allows us to make optimal use of the individual materials' specific properties. But this proves to be difficult in many cases," explains Dr. Anja Techel, Deputy Director of the Fraunhofer Institute for Material and Beam Technology IWS in Dresden. Her team believes in lasers: "With our newly-developed integrated laser tools, we can now even weld together combinations of materials, free of fissures or cracks." At Laser 2011, Fraunhofer scientists will present, for the first time, a new welding head capable not only of focusing with extreme precision but of moving back and forth across the seam with high frequency to mix the molten materials. When they harden, they create a stable bond.

Laser replaces chemistry

Lasers also save time and money in tool design. The molds used in the production of plastic fixtures and steering wheels, for example, have to be structured to give the finished component a visually and tactilely appealing surface. Most car manufacturers order a design from their suppliers, whose surface typically has the appearance of leather. Until now, the negative pattern used to create the design has been etched out of the steel tools used in injection molding -- a tedious and time-consuming process. "With lasers, the steel surface can not only be patterned more quickly, but also with greater scope for variety," explains Kristian Arntz of the Fraunhofer Institute for Production Technology IPT. "We can transfer any possible design directly from the CAD model to the tool surface: What will later become a groove in the plastic is preserved as a ridge, while the surrounding material is vaporized. The process is efficient, fully automatic, and highly variable."

Saving energy with low friction motors

Laser technology is also in demand in engine optimization. Engineers strive to keep friction as low as possible in order to improve efficiency. "That is true not only for the electric engines currently being developed, but also for classic internal combustion engines and diesel motors, as well as transmissions and bearings," says Arnold Gillner of the ILT. Ceramic, high-performance coatings are especially desirable, because they are not only resistant to wear but also smooth, which generates less friction. Coated metal components have until now been prohibitively expensive, being produced in plasma chambers in which the ceramic was vaporized and applied to the surface of the components. Fraunhofer scientists have now developed a less expensive and faster method in which work pieces are coated with ceramic nano-particles, then treated with a laser. This finishing process has already been applied to gear wheels and bearings.

Lasers can even be used to make specific modifications to the properties of engine parts. "Friction between the cylinder wall and piston is responsible for a big part of a motor's energy consumption. That is why we try to minimize it. This is especially important for engines featuring modern, automatic start-stop functions that are stressed by frequent ignition," says Gillner. "To protect them, we have to ensure that the cylinder is always coated with a film of oil. Laser technology can help reduce friction with special structuring processes that improve oil adhesion." Fraunhofer researchers aim to increase the engine's life-span and reduce energy consumption in this way.

Fitness program for electric cars

Lasers can even increase the efficiency and life-span of electric batteries. That is good news for manufacturers and owners of electric cars, since batteries continue to be extremely expensive. The engineers and scientists at Fraunhofer are currently working on various solutions to make batteries more durable and less expensive. One approach is to increase the surface area of the electrodes with appropriate coating in order to increase their efficiency. Another approach involves analyzing and optimizing production processes.

Manufacturers produce batteries using one anode and one cathode cell, which they then connect. In theory that sounds pretty simple, but in practice the fusing of copper anodes with aluminum cathodes creates brittle connections that break easily. That presents a problem for application in cars that sometimes drive on cobblestone or dirt roads. With the help of lasers, researchers at the ILT have succeeded in forming durable connections between electrodes without creating the culprit brittle alloys. Researchers at the IWS in Dresden have developed an alternative solution in which a laser warms the surfaces and rollers press them together. "Using roll plating with lasers and inductive pre-heating, we were able to create very stable connections with high electrical conductivity, with only a minimal loss of power," reports Anja Techel. "The finished batteries are very efficient. And since only small amounts of electrical energy are transformed into heat, these batteries do not require as much cooling."

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by Fraunhofer-Gesellschaft.

Free-standing single-walled carbon nanotube thin films

ScienceDaily (May 13, 2011) — Single-walled CNTs (SWCNTs) are a unique family of materials exhibiting diverse useful chemical and physical properties, researchers in Finland are demonstrating.

Thin films of SWCNTs have many unique properties such as high porosity and specific surface area, low density, high ratio of optical transmittance to sheet resistance, high thermal conductivity and chemical sensitivity, and tunable metallic and semiconducting properties.

Recently researchers from Department of Applied Physics at Aalto University (Finland) in collaboration with Canatu Ltd. (Finland) have discovered a simple and rapid method to prepare thin multifunctional single-walled carbon nanotube films without any substrate (free-standing films). Usually SWCNT films are prepared from suspensions of SWCNTs by a liquid filtration. This method typically involves several time and resource consuming and potentially detrimental liquid dispersion and purification steps ending up with dense SWCNT networks on a filter, which have a transfer issue. Moreover, preparation of free-standing films by the vacuum-filtration method is still a challenging task.

"Our method allows the preparation of SWCNT deposits both on different substrates and in the form of free-standing films during less than 15 s. This becomes possible due to the fact that the SWCNTs produced in the gas phase synthesis process gave very high purity and crystallinity, can be directly deposit from the gas to a substrate and accordingly be directly utilised without additional purification steps," says Dr. David P. Brown, CEO of the company Canatu Ltd, which commercializes the SWCNT films.

The method easily allows Canatu to alter the thickness of multifunctional free-standing SWCNT films from a sub-monolayer (when the amount of SWCNTs is insufficient to create a single continuous layer) to a few micrometers.

Collaboration with other Finnish universities

According to the researchers, the collaboration with other Finnish universities and institutions, Tampere University of Technology and Oulu University, was extremely important to investigate the unique properties and to demonstrate the multifunctionality of this unique material.

"We fabricated the state-of-the-art components for filtration of aerosol nanoparticles, transparent, flexible and highly conductive electrodes, extremely sensitive electrochemical sensors, polymer free saturable laser absorbers, gas heaters, thermo acoustic loudspeakers, and gas flow meters," says professor Esko I. Kauppinen, the leader of the research group.

SWCNT films - wide range of applications

"However, the wide range of applications is not limited to those reported in our paper. The superior mechanical and electrical properties of these films suggest potential uses in a broad range of other devices. As a filter, SWCNT films could be used for filtration of bacteria and viruses. The possibility to heat SWCNT films can be utilized for water or air sterilization. Additionally, since SWCNTs contain iron particles embedded inside them, one could exploit their magnetic properties. Their high strength coupled with high electrical conductivity could be employed in novel energy generators, electromagnetic interference shielding, flexible radio frequency identification tags, touch sensors, flat panel displays and static-charge dissipators. The ultrahigh surface area coupled with high electrical conductivity could be used in advanced solar cells and super capacitors," Dr. Albert G. Nasibulin, the leader of this project and the first author of the article related to the discovery of multifunctional free-standing SWCNTs concludes.

The results has been recently published in the journal ACS Nano.

Even though graphene has recently attracted much attention from the research community, some properties of SWCNTs, such as porosity, mechanical strength, and fine-tunability of optical and electrical properties, provide many applications where the flat, single-layered carbon structure cannot compete with its tubular 'brother'.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Aalto University, via AlphaGalileo.

Journal Reference:

Albert G. Nasibulin, Antti Kaskela, Kimmo Mustonen, Anton S. Anisimov, Virginia Ruiz, Samuli Kivisto¨, Simas Rackauskas, Marina Y. Timmermans, Marko Pudas, Brad Aitchison, Marko Kauppinen, David P. Brown, Oleg G. Okhotnikov, Esko I. Kauppinen. Multifunctional Free-Standing Single-Walled Carbon Nanotube Films. ACS Nano, 2011; : 110310090902026 DOI: 10.1021/nn200338r

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

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