New material can fold itself into hundreds of shapes

first_img The steps that the new material goes through to change from one shape to another. Call it one small step for material science, one giant leap for origami. Researchers have created the first heat-reactive polymer material that can not only remember its current shape but also memorize new ones. The material—which currently requires high temperatures to change shape and reset its memory—could lead to a new generation of reusable self-folding materials that could be useful for everything from medical implants to shape-shifting electronics.Self-folding materials aren’t new. The first generation of shape memory polymers folded into a single predetermined shape whenever they were heated. Later generations could be triggered by other stimuli, such as light, electrical charges, or a magnetic field. But they all relied on a property known as elasticity. When cool, their stringy polymers coil up. They straighten out into a new shape when heated, and then they bend right back to the default shape once they cool off again. In this way, they keep a “memory” of their original shape.But elastic shape memory materials can only memorize two or three shapes. A 2005 Science paper offered a possible route to hundreds or even thousands: Rather than elasticity—the tendency for a material to come back to the same shape—the paper demonstrated a way to trigger a change in a material’s plasticity, that is its ability to be reshaped. “The question was … can we incorporate these two shape-shifting behaviors in one polymer?” says Tao Xie, a chemical engineer at the State Key Laboratory of Chemical Engineering in Hangzhou, China.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)To make a material that is both plastic and elastic, Xie and colleagues started with a known elastic material: crosslinked poly(caprolactone), or PCL. To give the material plasticity, they added a chemical called 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). If it works, then above and below PCL’s elastic temperature point the material should flip between a default shape and one other shape. But if the temperature is raised above the plasticity threshold, then the TBD kicks in by creating chemical bonds between the polymer chains. If you physically manipulate the material into a new shape before this plastic “annealing” process starts, then the default shape gets replaced.But the trick for Xie was to combine PCL and TBD in such a way that the elastic and plastic temperatures were far enough away from each other that the material can switch cleanly between its different shapes. Otherwise, it could become a chaotic shape-shifting mess, like the death scene of the liquid metal T-1000 in the film Terminator 2. (You’re welcome, sci-fi geeks.)After months of fine-tuning the mixture of these chemicals, the team nailed the critical temperature gap. The new substance has transition temperatures of 70°C and 130°C for elasticity and plasticity, respectively. To demonstrate its multishape capabilities, Xie’s team turned a 30-millimeter square of the material into an origami masterpiece that could fold between two shapes using elasticity and change into other shapes using plasticity. Drs. Qian Zhao and Tao Xie center_img Not only did the material fold into multiple different shapes, but it could also snap between them hundreds of times with little sign of fatigue—a critical feature if the material is to be used in real-world applications, they report today in Science Advances.The team is already working on a version of the material that works at lower temperatures. “The biggest challenge for us is not necessarily technical, but rather our imagination of what the possibilities are with this type of shape-shifting behavior,” Xie says. He considers flexible electronics to be one possible “killer application.” Imagine an electronic newspaper that becomes plastic in the heat of your hands but always folds back down when you’re done reading it.The new material is a “step forward” in shape-programmable systems, says Timothy White, a chemical engineer at the Air Force Research Laboratory at the Wright Patterson Air Force Base in Dayton, Ohio, who was not involved in the research. Among the possible applications on his mind is a “reconfigurable antenna.” Not only could it be bent into many different shapes, but it would still always be able to retract.last_img read more

UV light could easily kill microbial stowaways to Mars

first_img David J. Smith/NASA UV light could easily kill microbial stowaways to Mars By Joshua SokolMar. 28, 2017 , 2:15 PM An 8-hour stratospheric flight on the NASA E-MIST balloon killed off even the hardiest microbes. Astrobiologists who dream of finding life on Mars also share a common nightmare. What if the very spacecraft intended to find martian microbes brings along Earth bacteria—and what if they fool experimenters, or contaminate the Red Planet? Now, a new study on Earth allays those fears, at least partially, showing that 8 hours of harsh ultraviolet (UV) light can decimate even the hardiest of bacteria.Interplanetary contamination is not an unreasonable fear. Some of the organisms with the best chance of surviving on Mars also have good chances of stowing away in the first place. A 2003 survey found a particularly stubborn strain of the rod-shaped bacteria Bacillus pumilus in even the cleanest of clean rooms at NASA’s Jet Propulsion Laboratory in Pasadena, California, where Mars-bound spacecraft are assembled.That strain, SAFR-032, has been able to survive as a spore in dry conditions with almost no nutrients. It can outlast waves of high-powered chemical disinfectants. It was even found to persist for 18 months in outer space, just outside the International Space Station (ISS).Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)UV rays from direct sunlight are the easiest way to kill it, according to those ISS experiments and others. The latest attempt to test its limits has confirmed that weakness by exposing SAFR-032 to an earthly place reminiscent of the Red Planet: Earth’s stratosphere.Like Mars, the stratosphere is thin, dry, cold, nutrient poor, and irradiated by harsh UV light. So in October 2015, microbiologist David Smith of NASA’s Ames Research Center in Mountain View, California, and his team launched SAFR-032 samples on a balloon 31 kilometers over New Mexico and Texas.Dangling from the balloon was a payload that extended flat plates out into the thin air and exposed tens of millions of spores—far more than the estimated 56,000 that rode on the surface of the Curiosity rover to Mars. “We sort of had a nightmare scenario and an intentionally high concentration in order to better understand how the bacterial population would respond,” Smith says.After 8 hours, less than one in 100,000 spores survived, Smith’s team reports this month in Astrobiology. “That’s reassuring,” says NASA’s Planetary Protection Officer Catharine Conley in Washington, D.C., who is responsible for managing contamination risks. It shows that a relaxation in standards since the Mars Viking landers in the 1970s was justified, she says.Once assembled, the twin Viking landers were each baked at 112°C for more than a day in an effort to reduce populations of bacteria by four orders of magnitude. By the time of the Pathfinder rover mission in the 1990s, engineers had dropped that step, concluding that Mars was dry and dead.From this study and previous ones, it seems that sunlight sterilizes about as well as baking. “We’re probably still at about a similar level of confidence, statistically speaking, that we’re protecting Mars,” Conley says.“The data are really good to know,” says microbiologist Ralf Möller of the German Aerospace Center in Cologne, who ran one of the studies of SAFR-032 exposed to space outside of the ISS. “For my lab at least it will have a big impact.”But outside experts also point to the literal flip side of Smith’s experiment. Spores on shaded, upside-down surfaces didn’t seem to take a hit. Of all the harsh conditions in the stratosphere, only UV radiation from sunlight really mattered. And real space probes often contain plenty of shady hiding spots like coatings, creases, interior compartments, and even layers of already-dead spores.“They are not building these spacecraft for UV microbial death,” says John Rummel, an astrobiologist at the SETI Institute in Mountain View, California. To really determine whether stowaway bacteria would survive on Mars, experiments need to use more complex surfaces, “not the kind of configurations that microbial ecologists find easy to count,” he says.In future experiments, Smith hopes to test other surfaces and other kinds of organisms. Another interesting question would be to see whether bacteria that can survive the stratosphere are evolving genetic advantages, Möller says.Ultimately, though, sending a probe into the wettest and warmest parts of Mars—the obvious places to search for life—will require stricter controls and maybe a return to old practices. Today, rovers are exploring relatively inhospitable parts of Mars. But areas that may contain near-surface water or ice, such as the recurring slope lineae where watery brines may periodically run down steep hills, are designated as “special regions” that require more care and would be currently off limits to spacecraft without further sterilization.Exploring those regions or landing near cracks on the moons Europa and Enceladus, which may harbor subsurface oceans, could require reinstituting the baking step, Conley says. Rummel thinks that may be overdue, even though it adds heat resistance to the list of things engineers have to worry about. “The biggest problem we have with sterilizing spacecraft is that we didn’t do it again after Viking,” he says.last_img read more

March of Dimes abruptly scales back research funding

first_img By Kelly ServickAug. 2, 2018 , 1:10 PM The cuts are also part of a strategic move to concentrate the organization’s energy around preterm birth, Moley adds. “It’s vital that we invest all of our resources into research program that have the greatest potential to impact the biggest threat right now facing newborn babies, and that’s preterm birth.”Researchers are lamenting the loss of a key funding source for early-stage research. “These sort of basic research grants in developmental biology are hard to come by,” says developmental biologist Maria Jasin of Memorial Sloan Kettering Cancer Center in New York City, who had a $250,000 award from March of Dimes to study a protein that influences DNA rearrangement during sperm and egg formation. “It’s really a shame that there will now be this hole.”Jasin and other grantees, blindsided by the cuts, are scrambling to find ways to keep their projects on track after learning in an email last week that they had lost the organization’s support.“The way they’ve approached this has been completely inhumane,” says molecular cell biologist Andrew Holland of Johns Hopkins University School of Medicine in Baltimore, Maryland, who received an email last week from March of Dimes telling him that he would not be receiving the remaining $160,000 on a 3-year, $250,000 grant from the organization to study a genetic pathway that appears to contribute to microcephaly. “The lack of transparency has been nothing short of appalling,” he says of the notification process.The message to grantees, obtained by Science, said the organization has, since the start of this year, been “transforming and modernizing its operation to ensure the long-term viability and impact of the organization” and that its research grant program was “being reviewed and modernized to ensure it is aligned with the organization’s broader transformation.”“I understand that these foundations sometimes have money problems, and they can stop things,” says chromosome biologist Andreas Hochwagen of New York University in New York City, whose March of Dimes–funded project has probed chromosomal mishaps during the creation of sperm and egg cells. But he was startled to learn last week that the organization would only disperse 2018 funding owed through the end of June. “For the whole month of July … they didn’t tell me that I wasn’t being supported anymore,” he says. “That I find a little outrageous.”Moley acknowledged that cut has created “a little bit of a gap” for some researchers. “I understand this is difficult for them, and I know the March of Dimes has been very generous in the past,” she says. “I’m hoping that as … we are getting more donations from other donors and other sources, we can go back to funding a more broad focus.”This isn’t the first transformation for March of Dimes. It was founded by then-President Franklin Roosevelt in 1938 as the National Foundation for Infantile Paralysis with the mission of fighting polio. But after polio vaccines became widely available, the organization shifted its focus to studying and preventing birth defects. March of Dimes, the 80-year-old nonprofit organization that has funded pioneering studies on premature birth, infant mortality, and birth defects, is abruptly scaling back its investment in research amid financial struggles—catching scientists by surprise.Last week, the group told 37 of 42 recipients of its individual investigator awards that it is cutting short their grants. On average, the grants total $300,000 over 3 years. It plans to maintain reduced funding for just five such awards; all are focused on understanding and preventing premature birth. The group, based in White Plains, New York, is also trimming grants to its prematurity research centers, which are housed at academic institutions around the United States. And it will not award any new research grants this year, but will still give out its 2-year, $150,000 awards for young scientists in 2019.The moves are part of an effort to slice about $3 million from the March of Dimes’s annual research budget of roughly $20 million, says Kelle Moley, the group’s chief scientific officer. The belt-tightening is the result of declining donations, particularly from the organization’s signature March for Babies. “The walks were our main funding source … and now there’s a million different kinds of walks,” she says. “They’re just not getting the donations that we used to get 10 or 20 years ago.” The group’s tax filings show that expenses exceeded revenue in each year from 2012 to 2016. It announced last year that it would be selling its national headquarters in White Plains.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*) March of Dimes abruptly scales back research fundingcenter_img March of Dimes, which sponsors the nationwide March for Babies fundraiser, will reduce its funding for research on birth defects and infant mortality. Parker Knight/Flickr (CC BY-SA) last_img read more