Chemists develop compounds capable of forming heath-resistant, economic and biocompatible gels

ScienceDaily (Nov. 9, 2011) — Eating a yogurt or a jelly, using a pharmaceutical or cosmetic cream or shampoo... are just some of the numerous everyday actions in which we use gels developed through a process of gelation. Researchers from Universitat Jaume I have patented a new family of compounds that enables to develop gels more resistant to high temperatures with a higher level of biocompatibility and able to work with a variety of organic solvents, and all this with an easy synthesis, scalable and low cost.

This family of compounds has significant applications in industries such as pharmaceuticals and cosmetics or food industry, among others.

A jellifying agent is a substance that when is added to a liquid, transforms it into ice. When the liquid used is water, it is called hydrogel. But if the solvents used are organic compounds, they use organojellifying compounds such as the developed by the group Sustainable chemistry: supported reactants and catalysts. Supramolecular chemistry from the UJI, led by the chair professor Santiago Luis. 'Normally, when we develop a compound or family compounds able to form organogels, they only act in such a way in a very small number of solvents. The fundamental difference is that our group of compounds is capable of forming gels with a very high range of solvents', the researcher explains.

Another contribution of the compound is its ability to maintain stability at temperatures up to 100° C, thus allowing the products to keep their properties. In addition, the basic chemical structures that form compounds are amino acids, which provide products that are in most cases biocompatible. 'As they have units easily acceptable by the biological world, they don't have incompatibility, allergies or toxicities problems," Santiago Luis stresses.

To all these advantages, we have to add the fact that these compounds with a jellifying action at low concentrations are cheap.

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Borrowing from brightly-colored birds: Physicists develop lasers inspired by nature

ScienceDaily (Oct. 13, 2011) — Researchers at Yale University are studying how two types of nanoscale structures on the feathers of birds produce brilliant and distinctive colors. The researchers are hoping that by borrowing these nanoscale tricks from nature they will be able to produce new types of lasers -- ones that can assemble themselves by natural processes.

The team will present their findings at the Optical Society's (OSA) Annual Meeting, Frontiers in Optics (FiO) 2011 (http://www.frontiersinoptics.com/), taking place in San Jose, Calif. next week.

Many of the colors displayed in nature are created by nanoscale structures that scatter light strongly at specific frequencies. In some cases, these structures create iridescence, where colors change with the angle of view -- like the shifting rainbows on a soap bubble. In other cases, the hues produced by the structures are steady and unchanging. The mechanism by which angle-independent colors are produced stumped scientists for 100 years: at first glance, these steady hues appeared to have been produced by a random jumble of proteins. But when researchers zoomed in on small sections of the protein at a time, quasi-ordered patterns began to emerge. The scientists found that it is this short-range order that scatters light preferentially at specific frequencies to produce the distinctive hues of a bluebird's wings, for example.

Inspired by feathers, the Yale physicists created two lasers that use this short-range order to control light. One model is based on feathers with tiny spherical air cavities packed in a protein called beta-keratin. The laser based on this model consists of a semiconductor membrane full of tiny air holes that trap light at certain frequencies. Quantum dots embedded between the holes amplify the light and produce the coherent beam that is the hallmark of a laser. The researchers also built a network laser using a series of interconnecting nano-channels, based on their observations of feathers whose beta-keratin takes the form of interconnecting channels in "tortuous and twisting forms." The network laser produces its emission by blocking certain colors of light while allowing others to propagate. In both cases, researchers can manipulate the lasers' colors by changing the width of the nano-channels or the spacing between the nano-holes.

What makes these short-range-ordered, bio-inspired structures different from traditional lasers is that, in principle, they can self-assemble, through natural processes similar to the formation of gas bubbles in a liquid. This means that engineers would not have to worry about the nanofabrication of the large-scale structure of the materials they design, resulting in cheaper, faster, and easier production of lasers and light-emitting devices.

One potential application for this work includes more efficient solar cells that can trap photons before converting them into electrons. The technology could also yield long-lasting paint, which could find uses in processes such as cosmetics and textiles. "Chemical paint will always fade," says lead author Hui Cao. But a physical "paint" whose nanostructure determines its color will never change. Cao describes a 40-million-year-old beetle fossil that her lab examined recently, and which had color-producing nanostructures. "With my eyes I can still see the color," she said. "It really lasts for a very long time."

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

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Borrowing from brightly-colored birds: Physicists develop lasers inspired by nature

ScienceDaily (Oct. 13, 2011) — Researchers at Yale University are studying how two types of nanoscale structures on the feathers of birds produce brilliant and distinctive colors. The researchers are hoping that by borrowing these nanoscale tricks from nature they will be able to produce new types of lasers -- ones that can assemble themselves by natural processes.

The team will present their findings at the Optical Society's (OSA) Annual Meeting, Frontiers in Optics (FiO) 2011 (http://www.frontiersinoptics.com/), taking place in San Jose, Calif. next week.

Many of the colors displayed in nature are created by nanoscale structures that scatter light strongly at specific frequencies. In some cases, these structures create iridescence, where colors change with the angle of view -- like the shifting rainbows on a soap bubble. In other cases, the hues produced by the structures are steady and unchanging. The mechanism by which angle-independent colors are produced stumped scientists for 100 years: at first glance, these steady hues appeared to have been produced by a random jumble of proteins. But when researchers zoomed in on small sections of the protein at a time, quasi-ordered patterns began to emerge. The scientists found that it is this short-range order that scatters light preferentially at specific frequencies to produce the distinctive hues of a bluebird's wings, for example.

Inspired by feathers, the Yale physicists created two lasers that use this short-range order to control light. One model is based on feathers with tiny spherical air cavities packed in a protein called beta-keratin. The laser based on this model consists of a semiconductor membrane full of tiny air holes that trap light at certain frequencies. Quantum dots embedded between the holes amplify the light and produce the coherent beam that is the hallmark of a laser. The researchers also built a network laser using a series of interconnecting nano-channels, based on their observations of feathers whose beta-keratin takes the form of interconnecting channels in "tortuous and twisting forms." The network laser produces its emission by blocking certain colors of light while allowing others to propagate. In both cases, researchers can manipulate the lasers' colors by changing the width of the nano-channels or the spacing between the nano-holes.

What makes these short-range-ordered, bio-inspired structures different from traditional lasers is that, in principle, they can self-assemble, through natural processes similar to the formation of gas bubbles in a liquid. This means that engineers would not have to worry about the nanofabrication of the large-scale structure of the materials they design, resulting in cheaper, faster, and easier production of lasers and light-emitting devices.

One potential application for this work includes more efficient solar cells that can trap photons before converting them into electrons. The technology could also yield long-lasting paint, which could find uses in processes such as cosmetics and textiles. "Chemical paint will always fade," says lead author Hui Cao. But a physical "paint" whose nanostructure determines its color will never change. Cao describes a 40-million-year-old beetle fossil that her lab examined recently, and which had color-producing nanostructures. "With my eyes I can still see the color," she said. "It really lasts for a very long time."

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

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Researchers develop optimal algorithm for determining focus error in eyes and cameras

ScienceDaily (Sep. 26, 2011) — University of Texas at Austin researchers have discovered how to extract and use information in an individual image to determine how far objects are from the focus distance, a feat only accomplished by human and animal visual systems until now.

Like a camera, the human eye has an auto-focusing system, but human auto-focusing rarely makes mistakes. And unlike a camera, humans do not require trial and error to focus an object.

Johannes Burge, a postdoctoral fellow in the College of Liberal Arts' Center for Perceptual Systems and co-author of the study, says it is significant that a statistical algorithm can now determine focus error, which indicates how much a lens needs to be refocused to make the image sharp, from a single image without trial and error.

"Our research on defocus estimation could deepen our understanding of human depth perception," Burge says. "Our results could also improve auto-focusing in digital cameras. We used basic optical modeling and well-understood statistics to show that there is information lurking in images that cameras have yet to tap."

The researchers' algorithm can be applied to any blurry image to determine focus error. An estimate of focus error also makes it possible to determine how far objects are from the focus distance.

In the human eye, inevitable defects in the lens, such as astigmatism, can help the visual system (via the retina and brain) compute focus error; the defects enrich the pattern of "defocus blur," the blur that is caused when a lens is focused at the wrong distance. Humans use defocus blur to both estimate depth and refocus their eyes. Many small animals use defocus as their primary depth cue.

"We are now one step closer to understanding how these feats are accomplished," says Wilson Geisler, director of the Center for Perceptual Systems and coauthor of the study. "The pattern of blur introduced by focus errors, along with the statistical regularities of natural images, makes this possible."

Burge and Geisler considered what happens to images as focus error increases: an increasing amount of detail is lost with larger errors. Then, they noted that even though the content of images varies considerably (e.g. faces, mountains, flowers), the pattern and amount of detail in images is remarkably constant. This constancy makes it possible to determine the amount of defocus and, in turn, to re-focus appropriately.

Their article was recently published in the Proceedings of the National Academy of Sciences. The research was supported by a grant from the National Institutes of Health.

The Center for Perceptual Systems is an integrated program that overlaps several separate departments: Neuroscience, Psychology, Electrical and Computer Engineering, Neurobiology, Computer Science, and Speech and Communication.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Texas at Austin.

Journal Reference:

J. Burge, W. S. Geisler. Optimal defocus estimation in individual natural images. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1108491108

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Researchers develop optimal algorithm for determining focus error in eyes and cameras

ScienceDaily (Sep. 26, 2011) — University of Texas at Austin researchers have discovered how to extract and use information in an individual image to determine how far objects are from the focus distance, a feat only accomplished by human and animal visual systems until now.

Like a camera, the human eye has an auto-focusing system, but human auto-focusing rarely makes mistakes. And unlike a camera, humans do not require trial and error to focus an object.

Johannes Burge, a postdoctoral fellow in the College of Liberal Arts' Center for Perceptual Systems and co-author of the study, says it is significant that a statistical algorithm can now determine focus error, which indicates how much a lens needs to be refocused to make the image sharp, from a single image without trial and error.

"Our research on defocus estimation could deepen our understanding of human depth perception," Burge says. "Our results could also improve auto-focusing in digital cameras. We used basic optical modeling and well-understood statistics to show that there is information lurking in images that cameras have yet to tap."

The researchers' algorithm can be applied to any blurry image to determine focus error. An estimate of focus error also makes it possible to determine how far objects are from the focus distance.

In the human eye, inevitable defects in the lens, such as astigmatism, can help the visual system (via the retina and brain) compute focus error; the defects enrich the pattern of "defocus blur," the blur that is caused when a lens is focused at the wrong distance. Humans use defocus blur to both estimate depth and refocus their eyes. Many small animals use defocus as their primary depth cue.

"We are now one step closer to understanding how these feats are accomplished," says Wilson Geisler, director of the Center for Perceptual Systems and coauthor of the study. "The pattern of blur introduced by focus errors, along with the statistical regularities of natural images, makes this possible."

Burge and Geisler considered what happens to images as focus error increases: an increasing amount of detail is lost with larger errors. Then, they noted that even though the content of images varies considerably (e.g. faces, mountains, flowers), the pattern and amount of detail in images is remarkably constant. This constancy makes it possible to determine the amount of defocus and, in turn, to re-focus appropriately.

Their article was recently published in the Proceedings of the National Academy of Sciences. The research was supported by a grant from the National Institutes of Health.

The Center for Perceptual Systems is an integrated program that overlaps several separate departments: Neuroscience, Psychology, Electrical and Computer Engineering, Neurobiology, Computer Science, and Speech and Communication.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Texas at Austin.

Journal Reference:

J. Burge, W. S. Geisler. Optimal defocus estimation in individual natural images. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1108491108

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

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Single-crystal arrays of graphene: Advance in efforts to develop a replacement for silicon in high-performance electronics

ScienceDaily (June 2, 2011) — University of Houston researchers have developed a method for creating single-crystal arrays of the material graphene, an advance that opens the possibility of a replacement for silicon in high-performance computers and electronics.

The work by UH researchers and their collaborators is featured on the cover of the June issue of Nature Materials.

Graphene is a one-atom-thick layer of carbon that was first fabricated in 2004. Single-crystal arrays of the material could be used to create a new class of high-speed transistors and integrated circuits that use less energy than silicon electronics because graphene conducts electricity with little resistance or heat generation.

But the industry needs a reliable and defect-free method for manufacturing large quantities of single crystals of graphene. The development reported in Nature Materials marks a step towards perfecting such a method.

"Using these seeds, we can grow an ordered array of thousands or millions of single crystals of graphene," said Qingkai Yu, the paper's first author. Yu developed the single-crystal growth process at the UH Center for Advanced Materials (CAM), where he was a research assistant professor of electrical and computer engineering.

"We hope the industry will look at these findings and consider the ordered arrays as a possible means of fabricating electronic devices," said Yu, who is now an assistant professor at Texas State University in San Marcos and remains a project leader at CAM.

Yu and Steven Pei, UH professor of electrical and computer engineering and CAM's deputy director, invented the graphene seeded-growth technique that UH patented in 2010.

"There is still a long way to go. However, this development makes the fabrication of integrated circuits with graphene transistors possible. This may actually be the first viable integrated circuit technology based on nano-electronics," Pei said.

Yong P. Chen, an assistant professor of nanoscience and physics at Purdue University, was the paper's co-corresponding author.

At CAM, single-crystal graphene arrays were grown on top of a copper foil inside a chamber containing methane gas using a process called chemical vapor deposition. This process was pioneered by Yu at CAM in 2008 and is now widely accepted as the standard method to create large-area graphene films for potential applications in touch-screen displays, e-books and solar cells.

"Graphene isn't there yet, in terms of high quality mass production like silicon, but this is a very important step in that direction," said Chen, who led the graphene characterization efforts at Purdue.

In addition to Yu and Pei, UH graduate students Wei Wu and Zhihua Su, postdoctoral researchers Zhihong Liu and Peng Peng and assistant professor Jiming Bao along with Chen and nine other researchers from Purdue University, Brookhaven National Laboratory, Argonne National Laboratories and Carl Zeiss SMT Inc. co-authored the paper.

Last year, two scientists received the Nobel Prize in physics for discovering graphene. At that time, Yu was working at CAM to develop ways to produce mass quantities of high-quality graphene.

The findings reported in Nature Materials demonstrated that researchers could control the growth of the ordered arrays. The researchers also were the first to demonstrate the electronic properties of individual grain boundaries.

The research was supported through a variety of funding sources, including the National Science Foundation, the U.S. Department of Energy, the Department of Homeland Security, the Defense Threat Reduction Agency, IBM Inc., the Welch Foundation, the Miller Family Endowment and Midwest Institute for Nanoelectronics Discovery.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Houston.

Journal Reference:

Qingkai Yu, Luis A. Jauregui, Wei Wu, Robert Colby, Jifa Tian, Zhihua Su, Helin Cao, Zhihong Liu, Deepak Pandey, Dongguang Wei, Ting Fung Chung, Peng Peng, Nathan P. Guisinger, Eric A. Stach, Jiming Bao, Shin-Shem Pei, Yong P. Chen. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition. Nature Materials, 2011; 10 (6): 443 DOI: 10.1038/nmat3010

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

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Single-crystal arrays of graphene: Advance in efforts to develop a replacement for silicon in high-performance electronics

ScienceDaily (June 2, 2011) — University of Houston researchers have developed a method for creating single-crystal arrays of the material graphene, an advance that opens the possibility of a replacement for silicon in high-performance computers and electronics.

The work by UH researchers and their collaborators is featured on the cover of the June issue of Nature Materials.

Graphene is a one-atom-thick layer of carbon that was first fabricated in 2004. Single-crystal arrays of the material could be used to create a new class of high-speed transistors and integrated circuits that use less energy than silicon electronics because graphene conducts electricity with little resistance or heat generation.

But the industry needs a reliable and defect-free method for manufacturing large quantities of single crystals of graphene. The development reported in Nature Materials marks a step towards perfecting such a method.

"Using these seeds, we can grow an ordered array of thousands or millions of single crystals of graphene," said Qingkai Yu, the paper's first author. Yu developed the single-crystal growth process at the UH Center for Advanced Materials (CAM), where he was a research assistant professor of electrical and computer engineering.

"We hope the industry will look at these findings and consider the ordered arrays as a possible means of fabricating electronic devices," said Yu, who is now an assistant professor at Texas State University in San Marcos and remains a project leader at CAM.

Yu and Steven Pei, UH professor of electrical and computer engineering and CAM's deputy director, invented the graphene seeded-growth technique that UH patented in 2010.

"There is still a long way to go. However, this development makes the fabrication of integrated circuits with graphene transistors possible. This may actually be the first viable integrated circuit technology based on nano-electronics," Pei said.

Yong P. Chen, an assistant professor of nanoscience and physics at Purdue University, was the paper's co-corresponding author.

At CAM, single-crystal graphene arrays were grown on top of a copper foil inside a chamber containing methane gas using a process called chemical vapor deposition. This process was pioneered by Yu at CAM in 2008 and is now widely accepted as the standard method to create large-area graphene films for potential applications in touch-screen displays, e-books and solar cells.

"Graphene isn't there yet, in terms of high quality mass production like silicon, but this is a very important step in that direction," said Chen, who led the graphene characterization efforts at Purdue.

In addition to Yu and Pei, UH graduate students Wei Wu and Zhihua Su, postdoctoral researchers Zhihong Liu and Peng Peng and assistant professor Jiming Bao along with Chen and nine other researchers from Purdue University, Brookhaven National Laboratory, Argonne National Laboratories and Carl Zeiss SMT Inc. co-authored the paper.

Last year, two scientists received the Nobel Prize in physics for discovering graphene. At that time, Yu was working at CAM to develop ways to produce mass quantities of high-quality graphene.

The findings reported in Nature Materials demonstrated that researchers could control the growth of the ordered arrays. The researchers also were the first to demonstrate the electronic properties of individual grain boundaries.

The research was supported through a variety of funding sources, including the National Science Foundation, the U.S. Department of Energy, the Department of Homeland Security, the Defense Threat Reduction Agency, IBM Inc., the Welch Foundation, the Miller Family Endowment and Midwest Institute for Nanoelectronics Discovery.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Houston.

Journal Reference:

Qingkai Yu, Luis A. Jauregui, Wei Wu, Robert Colby, Jifa Tian, Zhihua Su, Helin Cao, Zhihong Liu, Deepak Pandey, Dongguang Wei, Ting Fung Chung, Peng Peng, Nathan P. Guisinger, Eric A. Stach, Jiming Bao, Shin-Shem Pei, Yong P. Chen. Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition. Nature Materials, 2011; 10 (6): 443 DOI: 10.1038/nmat3010

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

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here