New silkworm diet produces colored silk and possible medical advantages

The Institute of Materials Research and Engineering (IMRE) in Singapore has developed a way to replace the traditional dying process necessary to make colored silk. A simple dietary change for the silkworm larva and they are able to produce silk in a variety of colors, with the color directly integrated into the fibers.

The process designed by the researchers involves feeding a diet of mulberries treated with fluorescent dye to the silkworms in the last four days of the larva stage. Once the silkworms ingest the dye they then turn the color of the dye they were fed. The silkworms then spin their cocoon with the resulting color of the silk matching the dye they ingested.

By integrating the dye directly into the silk before it is even spun creates a more environmentally friendly process for adding color to silk. The current process of dying silk requires large amounts of water as well as chemicals, and is extremely time consuming. By refining this process to get the desired colors, the need to dye silks in the traditional way may be eliminated.

Researchers believe that this method can be adapted for large scale farms and is very cost effective. The addition of the dyes to the silkworm diet does not alter the structure of the silk itself, so once the cocoons are spun, they can be harvested and processed utilizing normal procedures.

The integration of dye into the silkworm’s diet to create a colored silk has also opened the door to other possibilities. With the strength of silk itself, it has been used for many years as sutures and wound dressings. Researchers are now looking into the possibility of adding different compounds to the silkworm diet to produce silk with antibacterial, anticoagulant, and anti-inflammatory properties.

This new research holds the benefit of not only reducing the environmental footprint by eliminating the dying process for silk, but could lead to possible breakthroughs in medical treatments and wound care.

More information: Intrinsically Colored and Luminescent Silk, by Natalia C. Tansil et al., Advanced Materials, Article first published online: 9 FEB 2011. DOI:10.1002/adma.201003860

 

Researchers develop the first permanent anti-fog coating

Researchers under the supervision of Universite Laval professor Gaétan Laroche have developed the very first permanent anti-fog coating. Dr. Laroche and his colleagues present in the online edition of Applied Materials and Interfaces the details of this innovation which could eliminate, once and for all, the fog on eyeglasses, windshields, goggles, camera lenses, and on any transparent glass or plastic surface.

Fog forms on a surface when water vapor in the air condenses in fine droplets. "Despite appearances, the fog that forms on glasses is not a continuous film. In fact, it consists of tiny droplets of water that coalesce on the surface and reduce light transmission," explains Laroche, a professor at Université Laval's Faculty of Sciences and Engineering. "A good anti-fog coating should prevent the formation of such droplets."

Researchers used polyvinyl alcohol, a hydrophilic compound that allows water to spread uniformly. The challenge was to firmly attach the compound to the glass or plastic surface. To accomplish this, researchers applied four successive layers of molecules, which formed strong bonds with their adjoining layers, prior to adding the anti-fog compound over this base. The result was a thin, transparent, multilayered coating that does not alter the optical properties of the surface on which it is overlaid. In addition, the chemical bonds that join the different layers ensure the hardness and durability of the entire coating.

"Existing anti-fog treatments don't have these properties and won't withstand washing, so the product application must be repeated regularly," notes Professor Laroche. "Our coating, on the other hand, is permanent."

Two patents already protect this invention, which has numerous potential applications, including vehicle windshields, protective visors, camera lenses, binoculars, optical instruments used in chemistry and medicine, and corrective lenses. Negotiations are already underway with a major eyewear company interested in obtaining a license for this technology.

In addition to Gaétan Laroche, the study published in Applied Materials and Interfaces was coauthored by Pascale Chevallier, Stéphane Turgeon, Christian Sarra-Bournet, and Raphaël Turcotte.

Provided by Universite Laval

An icy gaze into the big bang: Quantum physicists investigate new states of matter in ultracold atom mixtures

Scientists of the Institute for Quantum Optics and Quantum Information (IQOQI) in Innsbruck, Austria, have reached a milestone in the exploration of quantum gas mixtures. In an international first, the research group led by Rudolf Grimm and Florian Schreck has succeeded in producing controlled strong interactions between two fermionic elements -- lithium-6 and potassium-40. This model system not only promises to provide new insights into solid-state physics but also shows intriguing analogies to the primordial substance right after the Big Bang.

According to theory, the whole universe consisted of quark-gluon plasma in the first split seconds after the Big Bang. On Earth this cosmic primordial "soup" can be observed in big particle accelerators when, for example, the nuclei of lead atoms are accelerated to nearly the speed of light and smashed into each other, which results in particle showers that are investigated with detectors. Now the group of quantum physicists led by Prof. Rudolf Grimm and PhD Florian Schreck from the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences together with Italian and Australian researchers has for the first time achieved strong controlled interactions between clouds of lithium-6 and potassium-40 atoms. Hence, they have established a model system that behaves in a similar way as the quark-gluon plasma, whose energy scale has a twenty times higher order of magnitude.

Hydrodynamic expansion

In 2008, the Innsbruck physicists found Feshbach resonances in an ultracold gas mixture consisting of lithium and potassium atoms, which they have used to modify quantum mechanical interactions between particles in a controlled way by applying a magnetic field. In the meantime, they have overcome all technical challenges and are now the first to also produce strong interactions between those particles. "The magnetic fields have to be adjusted precisely to one in 100000 and controlled accurately to achieve this result," explains Florian Schreck.

In the experiment the physicists prepare the ultracold gases of lithium-6 (Li) and potassium-40 (K) atoms in an optical trap and overlap them, with the smaller cloud of heavier K atoms residing in the centre of the Li cloud. After turning off the trap, the researchers observe the expansion of the quantum gases at different magnetic fields. "When the particles show a strong interaction, the gas clouds behave hydrodynamically," says Schreck. "An elliptical nucleus is formed in the centre of the particle cloud, where the potassium and lithium atoms interact. Moreover, the expansion velocity of the particles, which are different initially, become equal." According to theory, both phenomena suggest hydrodynamic behavior of the quantum gas mixture. "This behavior is the most striking phenomenon observed in quantum gases, when particles strongly interact," says Rudolf Grimm. "Therefore, this experiment opens up new research areas in the field of many-body physics."

New possibilities for exciting experiments

High energy physicists have made these two observations as well when producing quark-gluon plasmas in particle accelerators. The Innsbruck quantum gas experiment can be regarded as a model system to investigate cosmic phenomena that occurred immediately after the Big Bang. "In addition and above all, we can also use this system to address many questions of solid-state physics," says Rudolf Grimm, who is going to further explore the quantum gas mixture with his research group. "The big goal is to produce quantum condensates, such as Bose-Einstein condensates consisting of molecules made up of lithium and potassium atoms. This will tremendously increase our capabilities to realize novel states of matter."

The physicists have published their findings in the scientific journal Physical Review Letters. Their work is supported by the Austrian Science Fund (FWF) and the Special Research Area FoQuS, the European Science Foundation ESF within the framework of EuroQUAM, the Wittgenstein award granted by the FWF and the Austrian Ministry of Science.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by University of Innsbruck, via AlphaGalileo.

Journal Reference:

A. Trenkwalder, C. Kohstall, M. Zaccanti, D. Naik, A. Sidorov, F. Schreck, R. Grimm. Hydrodynamic Expansion of a Strongly Interacting Fermi-Fermi Mixture. Physical Review Letters, 2011; 106 (11) DOI: 10.1103/PhysRevLett.106.115304

More efficient means of creating, arranging carbon nanofibers developed

Carbon nanofibers hold promise for technologies ranging from medical imaging devices to precise scientific measurement tools, but the time and expense associated with uniformly creating nanofibers of the correct size has been an obstacle -- until now. A new study from North Carolina State University demonstrates an improved method for creating carbon nanofibers of specific sizes, as well as explaining the science behind the method.

"Carbon nanofibers have a host of potential applications, but their utility is affected by their diameter -- and controlling the diameter of nanofibers has historically been costly and time-consuming," says Dr. Anatoli Melechko, an associate professor of materials science and engineering at NC State and co-author of a paper describing the study.

Specifically, the researchers have shown that nickel nanoparticles coated with a ligand shell can be used to grow carbon nanofibers that are uniform in diameter. Ligands are small organic molecules that have functional groups (parts of the molecule) that bond directly to metals. Nickel nanoparticles are of particular interest because -- at high temperatures -- they can serve as catalysts for growing carbon nanofibers.

"What we learned is that the ligand shell, which is composed of trioctylphosphine, undergoes chemical changes at high temperatures -- gradually transforming into a graphite-like shell," says Dr. Joe Tracy, a co-author of the paper and assistant professor of materials science and engineering at NC State. "These 'graphitic' shells prevent the nickel nanoparticles from lumping together at elevated temperatures, which is a problem for high-temperature applications involving nanoparticles."

Using nanoparticles to grow nanofibers is useful, because the fibers tend to have the same diameter as the nanoparticles they are growing from. If you need nanofibers that are 20 nanometers (nm) in diameter, you would simply use nanoparticles that are 20 nm in diameter as your catalyst.

"This is why controlling the diameter of the nanoparticles is important. If they begin to lump together at high temperatures, you end up growing nanofibers of many different, larger sizes," Melechko says. "This research gives us a better fundamental understanding of the relationship between nickel nanoparticles, ligands and carbon nanofiber synthesis."

Using nanoparticles to grow nanofibers has another benefit -- it allows you to define where the nanofibers grow and how they are arranged. If you need the nanofibers to grow in a specific pattern, you would arrange the nanoparticles in that pattern before growing the fibers.

The paper was published online March 17 in ACS Applied Materials & Interfaces. The paper was co-authored by Melechko, Tracy; NC State Ph.D. students Mehmet Sarac, Aaron Johnston-Peck and Ryan Pearce; NC State undergraduate Robert Wilson; former NC State post-doctoral research associate Dr. Junwei Wang; and Dr. Kate Klein of the National Institute of Standards and Technology.

The research was funded by the National Science Foundation, U.S. Department of Energy, U.S. Department of Education, the Republic of Turkey and Protochips, Inc.

NC State's Department of Materials Science and Engineering is part of the university's College of Engineering.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by North Carolina State University.

Journal Reference:

Anatoli Melechko et al. Effects of Ligand Monolayers on Catalytic Nickel Nanoparticles for Synthesizing Vertically Aligned Carbon Nanofibers. ACS Applied Materials & Interfaces, March 17, 2011 DOI: 10.1021/am101290v

First permanent anti-fog coating developed

Researchers under the supervision of Université Laval professor Gaétan Laroche have developed the very first permanent anti-fog coating. Dr. Laroche and his colleagues present in the online edition of Applied Materials and Interfaces the details of this innovation which could eliminate, once and for all, the fog on eyeglasses, windshields, goggles, camera lenses, and on any transparent glass or plastic surface.

Fog forms on a surface when water vapor in the air condenses in fine droplets. "Despite appearances, the fog that forms on glasses is not a continuous film. In fact, it consists of tiny droplets of water that coalesce on the surface and reduce light transmission," explains Laroche, a professor at Université Laval's Faculty of Sciences and Engineering. "A good anti-fog coating should prevent the formation of such droplets."

Researchers used polyvinyl alcohol, a hydrophilic compound that allows water to spread uniformly. The challenge was to firmly attach the compound to the glass or plastic surface. To accomplish this, researchers applied four successive layers of molecules, which formed strong bonds with their adjoining layers, prior to adding the anti-fog compound over this base. The result was a thin, transparent, multilayered coating that does not alter the optical properties of the surface on which it is overlaid. In addition, the chemical bonds that join the different layers ensure the hardness and durability of the entire coating.

"Existing anti-fog treatments don't have these properties and won't withstand washing, so the product application must be repeated regularly," notes Professor Laroche. "Our coating, on the other hand, is permanent."

Two patents already protect this invention, which has numerous potential applications, including vehicle windshields, protective visors, camera lenses, binoculars, optical instruments used in chemistry and medicine, and corrective lenses. Negotiations are already underway with a major eyewear company interested in obtaining a license for this technology.

In addition to Gaétan Laroche, the study published in Applied Materials and Interfaces was coauthored by Pascale Chevallier, Stéphane Turgeon, Christian Sarra-Bournet, and Raphaël Turcotte.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by Université Laval.

Journal Reference:

Pascale Chevallier, Ste´phane Turgeon, Christian Sarra-Bournet, Raphae¨l Turcotte, Gae´tan Laroche. Characterization of Multilayer Anti-Fog Coatings. ACS Applied Materials & Interfaces, 2011; : 110307090243075 DOI: 10.1021/am1010964

Laser beam makes cells 'breathe in' water and potentially anti-cancer drugs

Shining a laser light on cells and then clicking off the light makes the cells "breathe in" surrounding water, providing a potentially powerful delivery system for chemotherapy drugs, as well as a non-invasive way to target anti-Alzheimer's medicines to the brain.

That's the conclusion of a report in ACS's The Journal of Physical Chemistry Letters.

Andrei Sommer's group, with Emad Aziz and colleagues note using this technique before to force cancer cells to sip up anti-cancer drugs and fluorescent dyes. Pulses of laser light can also change the volume of water inside cells in a way that plumps up wrinkles and makes skin look younger, the researchers found in an earlier study. "The potential applications of the technique range from anticancer strategies to the design principles of nano-steam engines," the report states. Using the so-called Liquidrom ambient approach, developed by Aziz's group, the researchers combined for the first time laser irradiation with soft X-rays obtained from a cyclotron radiation source to explore the molecular structure of interfacial water layers under ambient conditions.

The researchers now showed that laser light aimed at a cell causes the water inside the cell to expand. When the light goes off, the volume of water collapses again, creating a strong pull that also sucks in the water surrounding the cell. This "breathing in and out" of the water molecules can pull chemotherapy drugs into a cell faster than they would normally penetrate, the researchers found. "In other words, we discovered a powerful method to kill cancer cells by pumping anti-cancer drugs into them via laser light," said Sommer.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.

Journal Reference:

Andrei P. Sommer, Kai F. Hodeck, Dan Zhu, Alexander Kothe, Kathrin M. Lange, Hans-Jo¨rg Fecht, Emad F. Aziz. Breathing Volume into Interfacial Water with Laser Light. The Journal of Physical Chemistry Letters, 2011; : 562 DOI: 10.1021/jz2001503