This undated image made available by the Oregon Health & Science University in May 2013 shows developing cloned human embryos. Scientists have finally recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes. In the Wednesday, May 15, 2013 edition of the journal Cell, scientists at the Oregon Health & Science University report harvesting stem cells from six embryos. Shoukhrat Mitalipov, who led the research, said the success came not from a single technical innovation, but from revising a series of steps in the process. (AP Photo/Oregon Health & Science University)
This undated image made available by the Oregon Health & Science University in May 2013 shows developing cloned human embryos. Scientists have finally recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes. In the Wednesday, May 15, 2013 edition of the journal Cell, scientists at the Oregon Health & Science University report harvesting stem cells from six embryos. Shoukhrat Mitalipov, who led the research, said the success came not from a single technical innovation, but from revising a series of steps in the process. (AP Photo/Oregon Health & Science University)
This undated image made available by the Oregon Health & Science University in May 2013 shows a stem cell colony developed from cloned human embryos. Scientists have finally recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes. In the Wednesday, May 15, 2013 edition of the journal Cell, scientists at the Oregon Health & Science University report harvesting stem cells from six embryos. Shoukhrat Mitalipov, who led the research, said the success came not from a single technical innovation, but from revising a series of steps in the process. (AP Photo/Oregon Health & Science University)
NEW YORK (AP) ? Scientists have recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes.
Experts called the work significant, but noted that a different, simpler technique now under development may prove more useful.
Stem cells can turn into any cell of the body. Scientists are interested in using them to create transplant tissue for treating disease.
But transplants run the risk of rejection. So researchers had proposed creating tissue that used the patient's own DNA through cloning.
But in about a decade of trying, scientists had not been able to produce those stem cells from cloned human embryos.
The success is reported Wednesday in the journal Cell by a team based at Oregon Health & Science University.
Contact: Karen McNulty Walsh kmcnulty@bnl.gov 631-344-8350 DOE/Brookhaven National Laboratory
Approach could be useful in fabricating new kinds of materials with engineered properties
UPTON, NY-Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have discovered that DNA "linker" strands coax nano-sized rods to line up in way unlike any other spontaneous arrangement of rod-shaped objects. The arrangement-with the rods forming "rungs" on ladder-like ribbons linked by multiple DNA strands-results from the collective interactions of the flexible DNA tethers and may be unique to the nanoscale. The research, described in a paper published online in ACS Nano, a journal of the American Chemical Society, could result in the fabrication of new nanostructured materials with desired properties.
"This is a completely new mechanism of self-assembly that does not have direct analogs in the realm of molecular or microscale systems," said Brookhaven physicist Oleg Gang, lead author on the paper, who conducted the bulk of the research at the Lab's Center for Functional Nanomaterials (CFN, http://www.bnl.gov/cfn/).
Broad classes of rod-like objects, ranging from molecules to viruses, often exhibit typical liquid-crystal-like behavior, where the rods align with a directional dependence, sometimes with the aligned crystals forming two-dimensional planes over a given area. Rod shaped objects with strong directionality and attractive forces between their ends-resulting, for example, from polarized charge distribution-may also sometimes line up end-to-end forming linear one-dimensional chains.
Neither typical arrangement is found in the DNA-tethered nanorods.
"Our discovery shows that a qualitatively new regime emerges for nanoscale objects decorated with flexible molecular tethers of comparable sizes-a one-dimensional ladder-like linear arrangement that appears in the absence of end-to-end affinity among the rods," Gang said.
Alexei Tkachenko, the CFN scientist who developed the theory to explain the exceptional arrangement, elaborated: "Remarkably, the system has all three dimensions to live in, yet it chooses to form the linear, almost one-dimensional ribbons. It can be compared to how extra dimensions that are hypothesized by high-energy physicists become 'hidden,' so that we find ourselves in a 3-D world."
Tkachenko explains how the ladder-like alignment results from a fundamental symmetry breaking:
"Once a nanorod connects to another one side-by-side, it loses the cylindrical symmetry it had when it had free tethers all around. Then, the next nanorod will preferentially bind to another side of the first, where there are still DNA linkers available."
DNA as glue
Using synthetic DNA as a form of molecular glue to guide nanoparticle assembly has been a central approach of Gang's research at the CFN. His previous work has shown that strands of this molecule-better known for carrying the genetic code of living things-can pull nanoparticles together when strands bearing complementary sequences of nucleotide bases (known by the letters A, T, G, and C) are used as tethers, or inhibit binding when unmatched strands are used. Carefully controlling those attractive and inhibitory forces can lead to fine-tuned nanoscale engineering.
In the current study, the scientists used gold nanorods and single strands of DNA to explore arrangements made with complementary tethers attached to adjacent rods. They also examined the effects of using linker strands of varying lengths to serve as the tethering glue.
After mixing the various combinations, they studied the resulting arrangements using ultraviolet-visible spectroscopy at the CFN, and also with small-angle x-ray scattering at Brookhaven's National Synchrotron Light Source (NSLS, http://www.bnl.gov/ps/nsls/about-NSLS.asp). They also used techniques to "freeze" the action at various points during assembly and observed those static phases using scanning electron microscopy to get a better understanding of how the process progressed over time.
The various analysis methods confirmed the side-by-side arrangement of the nanorods arrayed like rungs on a ladder-like ribbon during the early stages of assembly, followed later by stacking of the ribbons and finally larger-scale three-dimensional aggregation due to the formation of DNA bridges between the ribbons.
This staged assembly process, called hierarchical, is reminiscent of self-assembly in many biological systems (for example, the linking of amino acids into chains followed by the subsequent folding of these chains to form functional proteins).
The stepwise nature of the assembly suggested to the team that the process could be stopped at the intermediate stages. Using "blocker" strands of DNA to bind up the remaining free tethers on the linear ribbon-like structures, they demonstrated their ability to prevent the later-stage interactions that form aggregate structures.
"Stopping the assembly process at the ladder-like ribbon stage could potentially be applied for the fabrication of linear structures with engineered properties," Gang said. "For example by controlling plasmonic or fluorescent properties-the materials' responses to light-we might be able to make nanoscale light concentrators or light guides, and be able to switch them on demand."
###
Additional authors on this study include: Stephanie Vial of CFN and the International Iberian Nanotechnology Laboratory in Braga, Portugal, and Dmytro Nykypanchuk, and Kevin Yager, all of CFN.
This research was funded by the DOE Office of Science (BES), which also provides operations support for the CFN and NSLS at Brookhaven Lab.
The Center for Functional Nanomaterials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the U.S. Department of Energy, Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. More information about the DOE NSRCs: http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers.
One of the world's most widely used scientific research facilities, the National Synchrotron Light Source (NSLS) is host each year to 2,400 researchers from more than 400 universities, laboratories, and companies. Research conducted at the NSLS has yielded advances in biology, physics, chemistry, geophysics, medicine, and materials science. More information about NSLS: http://www.bnl.gov/ps/nsls/About-NSLS.asp.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Related Links
Scientific paper:
Linear Mesostructures in DNA-Nanorod Self-Assembly
Online version of this news release with related graphics:
http://www.bnl.gov/newsroom/news.php?a=11540
Press releases on previous related work:
Multi-Component Nano-Structures with Tunable Optical Properties
Switchable Nanostructures Made with DNA
DNA-Based Assembly Line for Precision Nano-Cluster Construction
Media contacts: Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov, or Peter Genzer, (631) 344-3174, genzer@bnl.gov
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.
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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Contact: Karen McNulty Walsh kmcnulty@bnl.gov 631-344-8350 DOE/Brookhaven National Laboratory
Approach could be useful in fabricating new kinds of materials with engineered properties
UPTON, NY-Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have discovered that DNA "linker" strands coax nano-sized rods to line up in way unlike any other spontaneous arrangement of rod-shaped objects. The arrangement-with the rods forming "rungs" on ladder-like ribbons linked by multiple DNA strands-results from the collective interactions of the flexible DNA tethers and may be unique to the nanoscale. The research, described in a paper published online in ACS Nano, a journal of the American Chemical Society, could result in the fabrication of new nanostructured materials with desired properties.
"This is a completely new mechanism of self-assembly that does not have direct analogs in the realm of molecular or microscale systems," said Brookhaven physicist Oleg Gang, lead author on the paper, who conducted the bulk of the research at the Lab's Center for Functional Nanomaterials (CFN, http://www.bnl.gov/cfn/).
Broad classes of rod-like objects, ranging from molecules to viruses, often exhibit typical liquid-crystal-like behavior, where the rods align with a directional dependence, sometimes with the aligned crystals forming two-dimensional planes over a given area. Rod shaped objects with strong directionality and attractive forces between their ends-resulting, for example, from polarized charge distribution-may also sometimes line up end-to-end forming linear one-dimensional chains.
Neither typical arrangement is found in the DNA-tethered nanorods.
"Our discovery shows that a qualitatively new regime emerges for nanoscale objects decorated with flexible molecular tethers of comparable sizes-a one-dimensional ladder-like linear arrangement that appears in the absence of end-to-end affinity among the rods," Gang said.
Alexei Tkachenko, the CFN scientist who developed the theory to explain the exceptional arrangement, elaborated: "Remarkably, the system has all three dimensions to live in, yet it chooses to form the linear, almost one-dimensional ribbons. It can be compared to how extra dimensions that are hypothesized by high-energy physicists become 'hidden,' so that we find ourselves in a 3-D world."
Tkachenko explains how the ladder-like alignment results from a fundamental symmetry breaking:
"Once a nanorod connects to another one side-by-side, it loses the cylindrical symmetry it had when it had free tethers all around. Then, the next nanorod will preferentially bind to another side of the first, where there are still DNA linkers available."
DNA as glue
Using synthetic DNA as a form of molecular glue to guide nanoparticle assembly has been a central approach of Gang's research at the CFN. His previous work has shown that strands of this molecule-better known for carrying the genetic code of living things-can pull nanoparticles together when strands bearing complementary sequences of nucleotide bases (known by the letters A, T, G, and C) are used as tethers, or inhibit binding when unmatched strands are used. Carefully controlling those attractive and inhibitory forces can lead to fine-tuned nanoscale engineering.
In the current study, the scientists used gold nanorods and single strands of DNA to explore arrangements made with complementary tethers attached to adjacent rods. They also examined the effects of using linker strands of varying lengths to serve as the tethering glue.
After mixing the various combinations, they studied the resulting arrangements using ultraviolet-visible spectroscopy at the CFN, and also with small-angle x-ray scattering at Brookhaven's National Synchrotron Light Source (NSLS, http://www.bnl.gov/ps/nsls/about-NSLS.asp). They also used techniques to "freeze" the action at various points during assembly and observed those static phases using scanning electron microscopy to get a better understanding of how the process progressed over time.
The various analysis methods confirmed the side-by-side arrangement of the nanorods arrayed like rungs on a ladder-like ribbon during the early stages of assembly, followed later by stacking of the ribbons and finally larger-scale three-dimensional aggregation due to the formation of DNA bridges between the ribbons.
This staged assembly process, called hierarchical, is reminiscent of self-assembly in many biological systems (for example, the linking of amino acids into chains followed by the subsequent folding of these chains to form functional proteins).
The stepwise nature of the assembly suggested to the team that the process could be stopped at the intermediate stages. Using "blocker" strands of DNA to bind up the remaining free tethers on the linear ribbon-like structures, they demonstrated their ability to prevent the later-stage interactions that form aggregate structures.
"Stopping the assembly process at the ladder-like ribbon stage could potentially be applied for the fabrication of linear structures with engineered properties," Gang said. "For example by controlling plasmonic or fluorescent properties-the materials' responses to light-we might be able to make nanoscale light concentrators or light guides, and be able to switch them on demand."
###
Additional authors on this study include: Stephanie Vial of CFN and the International Iberian Nanotechnology Laboratory in Braga, Portugal, and Dmytro Nykypanchuk, and Kevin Yager, all of CFN.
This research was funded by the DOE Office of Science (BES), which also provides operations support for the CFN and NSLS at Brookhaven Lab.
The Center for Functional Nanomaterials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the U.S. Department of Energy, Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. More information about the DOE NSRCs: http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers.
One of the world's most widely used scientific research facilities, the National Synchrotron Light Source (NSLS) is host each year to 2,400 researchers from more than 400 universities, laboratories, and companies. Research conducted at the NSLS has yielded advances in biology, physics, chemistry, geophysics, medicine, and materials science. More information about NSLS: http://www.bnl.gov/ps/nsls/About-NSLS.asp.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Related Links
Scientific paper:
Linear Mesostructures in DNA-Nanorod Self-Assembly
Online version of this news release with related graphics:
http://www.bnl.gov/newsroom/news.php?a=11540
Press releases on previous related work:
Multi-Component Nano-Structures with Tunable Optical Properties
Switchable Nanostructures Made with DNA
DNA-Based Assembly Line for Precision Nano-Cluster Construction
Media contacts: Karen McNulty Walsh, (631) 344-8350, kmcnulty@bnl.gov, or Peter Genzer, (631) 344-3174, genzer@bnl.gov
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.
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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Niantic Labs' Field Trip is a location-discovery app that runs in the background during your aimless wanderings, piping up when you stumble across something notable. Unfortunately, for software designed to help you travel, it'd only made the one journey itself -- to the UK, and no further. Fortunately, the Google-owned company has sent the Android version of the app truly global, opening it up to over 80 countries to find stuff in. Niantic Labs has also jammed in 30 languages and auto-translation, so if you find a restaurant review in an unfamiliar tongue, you won't have to resort to negotiating with the locals.
'Fish thermometer' reveals long-standing, global impact of climate changePublic release date: 15-May-2013 [ | E-mail | Share ]
Contact: William Cheung w.cheung@fisheries.ubc.ca 778-837-7252 University of British Columbia
Climate change has been impacting global fisheries for the past four decades by driving species towards cooler, deeper waters, according to University of British Columbia scientists.
In a Nature study published this week, UBC researchers used temperature preferences of fish and other marine species as a sort of "thermometer" to assess effects of climate change on the world's oceans between 1970 and 2006.
They found that global fisheries catches were increasingly dominated by warm-water species as a result of fish migrating towards the poles in response to rising ocean temperatures.
"One way for marine animals to respond to ocean warming is by moving to cooler regions," says the study's lead author William Cheung, an assistant professor at UBC's Fisheries Centre. "As a result, places like New England on the northeast coast of the U.S. saw new species typically found in warmer waters, closer to the tropics.
"Meanwhile in the tropics, climate change meant fewer marine species and reduced catches, with serious implications for food security."
"We've been talking about climate change as if it's something that's going to happen in the distant future our study shows that it has been affecting our fisheries and oceans for decades," says Daniel Pauly, principal investigator with UBC's Sea Around Us Project and the study's co-author. "These global changes have implications for everyone in every part of the planet."
###
A summary of the study is available at http://www.pewenvironment.org/news-room/fact-sheets/warming-oceans-are-reshaping-fisheries-85899474034.
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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
'Fish thermometer' reveals long-standing, global impact of climate changePublic release date: 15-May-2013 [ | E-mail | Share ]
Contact: William Cheung w.cheung@fisheries.ubc.ca 778-837-7252 University of British Columbia
Climate change has been impacting global fisheries for the past four decades by driving species towards cooler, deeper waters, according to University of British Columbia scientists.
In a Nature study published this week, UBC researchers used temperature preferences of fish and other marine species as a sort of "thermometer" to assess effects of climate change on the world's oceans between 1970 and 2006.
They found that global fisheries catches were increasingly dominated by warm-water species as a result of fish migrating towards the poles in response to rising ocean temperatures.
"One way for marine animals to respond to ocean warming is by moving to cooler regions," says the study's lead author William Cheung, an assistant professor at UBC's Fisheries Centre. "As a result, places like New England on the northeast coast of the U.S. saw new species typically found in warmer waters, closer to the tropics.
"Meanwhile in the tropics, climate change meant fewer marine species and reduced catches, with serious implications for food security."
"We've been talking about climate change as if it's something that's going to happen in the distant future our study shows that it has been affecting our fisheries and oceans for decades," says Daniel Pauly, principal investigator with UBC's Sea Around Us Project and the study's co-author. "These global changes have implications for everyone in every part of the planet."
###
A summary of the study is available at http://www.pewenvironment.org/news-room/fact-sheets/warming-oceans-are-reshaping-fisheries-85899474034.
[ | E-mail | Share ]
?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
May 15, 2013 ? Climate change has been impacting global fisheries for the past four decades by driving species towards cooler, deeper waters, according to University of British Columbia scientists.
In a Nature study published this week, UBC researchers used temperature preferences of fish and other marine species as a sort of "thermometer" to assess effects of climate change on the world's oceans between 1970 and 2006.
They found that global fisheries catches were increasingly dominated by warm-water species as a result of fish migrating towards the poles in response to rising ocean temperatures.
"One way for marine animals to respond to ocean warming is by moving to cooler regions," says the study's lead author William Cheung, an assistant professor at UBC's Fisheries Centre. "As a result, places like New England on the northeast coast of the U.S. saw new species typically found in warmer waters, closer to the tropics.
"Meanwhile in the tropics, climate change meant fewer marine species and reduced catches, with serious implications for food security."
"We've been talking about climate change as if it's something that's going to happen in the distant future -- our study shows that it has been affecting our fisheries and oceans for decades," says Daniel Pauly, principal investigator with UBC's Sea Around Us Project and the study's co-author. "These global changes have implications for everyone in every part of the planet."
A summary of the study is available at http://www.pewenvironment.org/news-room/fact-sheets/warming-oceans-are-reshaping-fisheries-85899474034.
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The above story is reprinted from materials provided by University of British Columbia.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
William W. L. Cheung, Reg Watson, Daniel Pauly. Signature of ocean warming in global fisheries catch. Nature, 2013; 497 (7449): 365 DOI: 10.1038/nature12156
Note: If no author is given, the source is cited instead.
May 15, 2013 ? This composite image of a galaxy illustrates how the intense gravity of a supermassive black hole can be tapped to generate immense power. The image contains X-ray data from NASA's Chandra X-ray Observatory (blue), optical light obtained with the Hubble Space Telescope (gold) and radio waves from the NSF's Very Large Array (pink).
This multi-wavelength view shows 4C+29.30, a galaxy located some 850 million light years from Earth. The radio emission comes from two jets of particles that are speeding at millions of miles per hour away from a supermassive black hole at the center of the galaxy. The estimated mass of the black hole is about 100 million times the mass of our Sun. The ends of the jets show larger areas of radio emission located outside the galaxy.
The X-ray data show a different aspect of this galaxy, tracing the location of hot gas. The bright X-rays in the center of the image mark a pool of million-degree gas around the black hole. Some of this material may eventually be consumed by the black hole, and the magnetized, whirlpool of gas near the black hole could in turn, trigger more output to the radio jet.
Most of the low-energy X-rays from the vicinity of the black hole are absorbed by dust and gas, probably in the shape of a giant doughnut around the black hole. This doughnut, or torus blocks all the optical light produced near the black hole, so astronomers refer to this type of source as a hidden or buried black hole. The optical light seen in the image is from the stars in the galaxy.
The bright spots in X-ray and radio emission on the outer edges of the galaxy, near the ends of the jets, are caused by extremely high energy electrons following curved paths around magnetic field lines. They show where a jet generated by the black hole has plowed into clumps of material in the galaxy (mouse over the image for the location of these bright spots). Much of the energy of the jet goes into heating the gas in these clumps, and some of it goes into dragging cool gas along the direction of the jet. Both the heating and the dragging can limit the fuel supply for the supermassive black hole, leading to temporary starvation and stopping its growth. This feedback process is thought to cause the observed correlation between the mass of the supermassive black hole and the combined mass of the stars in the central region or bulge or a galaxy.
These results were reported in two different papers. The first, which concentrated on the effects of the jets on the galaxy, is available online and was published in the May 10, 2012 issue of The Astrophysical Journal. It is led by Aneta Siemiginowska from the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, MA and the co-authors are ?ukasz Stawarz, from the Institute of Space and Astronautical Science in Yoshinodai, Japan; Teddy Cheung from the National Academy of Sciences in Washington, DC; Thomas Aldcroft from CfA; Jill Bechtold from University of Arizona in Tucson, AZ; Douglas Burke from CfA; Daniel Evans from CfA; Joanna Holt from Leiden University in Leiden, The Netherlands; Marek Jamrozy from Jagiellonian University in Krakow, Poland; and Giulia Migliori from CfA. The second, which concentrated on the supermassive black hole, is available online and was published in the October 20, 2012 issue of The Astrophysical Journal. It is led by Malgorzata Sobolewska from CfA, and the co-authors are Aneta Siemiginowska, Giulia Migliori, ?ukasz Stawarz, Marek Jamrozy, Daniel Evans, and Teddy Cheung.
Contact: Wouter Sempels wouter.sempels@chem.kuleuven.be 32-016-327-399 KU Leuven
Ever notice how a dried coffee stain has a thicker outer rim, while the middle of the stain remains almost unsoiled? This 'coffee ring effect' also occurs in other materials. Researchers from the Departments of Chemical Engineering and Chemistry at KU Leuven have now discovered how to counteract coffee rings with 'surfactants', i.e. soap. The key to the discovery was not a kitchen towel, but a bacterium that counteracts the coffee ring effect at the microscopic level. The findings were published in a recent edition of the leading journal Nature Communications.
When a coffee ring dries, its edges become noticeably darker and thicker. This occurs because the coffee particles move toward the edge of the stain while the water in the liquid evaporates. At a microscopic level, this coffee ring effect can also be seen in liquids with particles of other materials such as plastic and wood.
In various industrial applications applying an even coat of paint or varnish, for example the coffee ring effect can be particularly troublesome and scientists have long been seeking ways to counteract it. Raf De Dier and Wouter Sempels (Departments of Chemical Engineering and Chemistry) have now described a solution based on examples found in nature. De Dier and Sempels carried out experiments and calculations on nanomaterials as well as on a particularly promising bacterium, Pseudomonas aeruginosa.
Pseudomonas aeruginosa is a dangerous bacterium that can cause infections in open wounds. "A Pseudomonas aeruginosa bacteria colony wants to find as large a breeding ground as possible. To avoid overconcentration on the edges of a wound when spreading itself during the drying-out process, the bacterium produces substances that counteract the coffee ring effect."
These surface-tension-disrupting substances are called surfactants. Detergents such as soap are also surfactants. "Add soap to a stain a coffee stain or any other stain and you will still get a coffee ring effect. But at the same time the soap causes a counterflow from the edge back towards the centre of the stain in such a way that the small particles material or bacteria end up in a kind of whirlwind. In this way, you get a more uniform distribution of particles as evaporation occurs."
"If we genetically modify the bacteria so they can no longer produce surfactants, the coffee ring effect remains fully intact. Our findings on Pseudomonas aeruginosa also apply to other bacteria. For the biomedical sector, this study contributes primarily to our understanding of a biological system." But surfactants could also potentially be added to nanomaterials, and that makes De Dier and Sempels' findings interesting for industry. "Surfactants are inexpensive. It won't be long before we start seeing them turn up in industrial applications."
###
Contact:
Wouter Sempels, KU Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, tel +32 (0)16 32 73 99, e-mail wouter.sempels@chem.kuleuven.be;
Raf De Dier, KU Leuven, Department of Chemical Engineering , Department of Soft Matter Rheology and Technology, tel +32 (0)16 32 27 01, e-mail raf.dedier@cit.kuleuven.be
More information:
The full text of the study "Auto-production of biosurfactants reverses the coffee ring effect in a bacterial system" by Wouter Sempels*, Raf De Dier*, Hideaki Mizuno , Johan Hofkens & Jan Vermant is available on the Nature website: http://www.nature.com/ncomms/journal/v4/n4/full/ncomms2746.html
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Contact: Wouter Sempels wouter.sempels@chem.kuleuven.be 32-016-327-399 KU Leuven
Ever notice how a dried coffee stain has a thicker outer rim, while the middle of the stain remains almost unsoiled? This 'coffee ring effect' also occurs in other materials. Researchers from the Departments of Chemical Engineering and Chemistry at KU Leuven have now discovered how to counteract coffee rings with 'surfactants', i.e. soap. The key to the discovery was not a kitchen towel, but a bacterium that counteracts the coffee ring effect at the microscopic level. The findings were published in a recent edition of the leading journal Nature Communications.
When a coffee ring dries, its edges become noticeably darker and thicker. This occurs because the coffee particles move toward the edge of the stain while the water in the liquid evaporates. At a microscopic level, this coffee ring effect can also be seen in liquids with particles of other materials such as plastic and wood.
In various industrial applications applying an even coat of paint or varnish, for example the coffee ring effect can be particularly troublesome and scientists have long been seeking ways to counteract it. Raf De Dier and Wouter Sempels (Departments of Chemical Engineering and Chemistry) have now described a solution based on examples found in nature. De Dier and Sempels carried out experiments and calculations on nanomaterials as well as on a particularly promising bacterium, Pseudomonas aeruginosa.
Pseudomonas aeruginosa is a dangerous bacterium that can cause infections in open wounds. "A Pseudomonas aeruginosa bacteria colony wants to find as large a breeding ground as possible. To avoid overconcentration on the edges of a wound when spreading itself during the drying-out process, the bacterium produces substances that counteract the coffee ring effect."
These surface-tension-disrupting substances are called surfactants. Detergents such as soap are also surfactants. "Add soap to a stain a coffee stain or any other stain and you will still get a coffee ring effect. But at the same time the soap causes a counterflow from the edge back towards the centre of the stain in such a way that the small particles material or bacteria end up in a kind of whirlwind. In this way, you get a more uniform distribution of particles as evaporation occurs."
"If we genetically modify the bacteria so they can no longer produce surfactants, the coffee ring effect remains fully intact. Our findings on Pseudomonas aeruginosa also apply to other bacteria. For the biomedical sector, this study contributes primarily to our understanding of a biological system." But surfactants could also potentially be added to nanomaterials, and that makes De Dier and Sempels' findings interesting for industry. "Surfactants are inexpensive. It won't be long before we start seeing them turn up in industrial applications."
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Contact:
Wouter Sempels, KU Leuven, Department of Chemistry, Division of Molecular Imaging and Photonics, tel +32 (0)16 32 73 99, e-mail wouter.sempels@chem.kuleuven.be;
Raf De Dier, KU Leuven, Department of Chemical Engineering , Department of Soft Matter Rheology and Technology, tel +32 (0)16 32 27 01, e-mail raf.dedier@cit.kuleuven.be
More information:
The full text of the study "Auto-production of biosurfactants reverses the coffee ring effect in a bacterial system" by Wouter Sempels*, Raf De Dier*, Hideaki Mizuno , Johan Hofkens & Jan Vermant is available on the Nature website: http://www.nature.com/ncomms/journal/v4/n4/full/ncomms2746.html
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Public release date: 16-May-2013
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