How We Localize Surround Sound

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. The ability of humans and other animals to pinpoint the location of sound sources is remarkably good, scientists say. Since the early 1900s, many studies have been performed on the underlying physical mechanisms of how animals’ ears can determine “directional sound.” In a recent study and review, scientists Axel Michelsen and Ole Naesbye Larsen from the University of Southern Denmark have offered a quantitative analysis of how animals like insects and small birds can localize the direction to sound sources. These animals are too small to take advantage of the directional cues used by humans (changes with direction of the sound pressure and time of arrival of sound at the ears). However, the results of the study, which is published in a recent issue of Bioinspiration and Biomimetics, could have important implications for humans, as well.“We now have an understanding of the physics of these hearing systems, and can make quantitative predictions that can be tested in experiments,” Michelsen told PhysOrg.com.In order to determine where a sound is coming from, animals can use information based on the differences between two ears (called “binaural” cues) or information, such as from the shape, of a single ear (called “monaural” cues). Michelsen and Larsen explain that many smaller non-mammalian animals compute the azimuth (horizontal plane) of sound sources using binaural cues with ears that receive sound at both the outer and inner surface of the eardrum, which is called “pressure difference reception.”Birds and grasshoppers are some of the small animals that can use pressure difference reception, which is characterized by having two ears that are connected by an air tunnel through the animal’s body. As the sound travels between ears through the animal’s body, each eardrum is activated by different sounds at its outer and inner surface that help the animal determine the source of the sound. For example, the ear facing more toward the sound source vibrates with a larger amplitude than the eardrum facing away. As the researchers emphasize, both sound transmission through the body and binaural cues help the animal localize sound. Although scientists know the general mechanisms responsible for sound localization, the difficulty of performing experiments with animals in non-interfering environments makes a detailed model elusive. Michelsen and Larsen explain that scientists are still far from understanding certain components of directional hearing, such as the physics of sound transmission through channels in the body, and how an animal’s habitat influences its hearing mechanisms. “What is needed now is to get a much better understanding of directional hearing in the natural habitats, where thick vegetation, etc., degrade sounds,” Michelsen said.Humans, on the other hand, use a different type of sound receiver, one that uses simply “pressure reception.” In human ears, only the outer surface is exposed to sound, and an opening (the Eustachian tube) allows an equalization of pressure, but doesn’t allow sound to enter the middle ear. While humans with normal hearing have a surprisingly good ability to determine sound origins, individuals who use hearing aids often have only a very limited ability to localize sounds.But, as Michelsen and Larsen explain, using techniques from pressure difference reception, like the birds and grasshoppers have, may improve the sound localization ability of human hearing aids. One possibility is to let the hearing aids in the two ears exchange information by means of radio signals, which enhances the binaural and time cues in both ears, and thereby helps a user determine the direction of a sound. As Michelsen explains, the ability to determine the source of sound is not just a luxury, but often a necessary survival skill.“Praying mantids flying at night can hear the cries of hunting bats, but not determine the direction to the bats,” Michelsen said. “It probably means that more mantids get eaten by bats than would have been the case if their hearing system had been equipped with pressure difference reception.”Much more information remains to be learned about directional hearing in different animals. From frogs, which hear with their lungs and mouth, to crickets, which have ears on their front legs just below the knee, the ability to hear is complex and can offer a deeper understanding of nature’s remarkable acoustic abilities.More information: Michelsen, Axel, and Larsen, Ole Naesbye. “Pressure difference receiving ears.” Bioinsp. Biomim. 3 (2008) 011001 (18pp).Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. The cricket’s ears are located on its front legs, and have four acoustic inputs. Sound first reaches the outer eardrum, which is connected to an acoustic trachea, a transverse trachea, and an acoustic trachea on the opposite side, allowing the sound to pass all the way through the cricket’s body. Credit: Michelsen and Larsen Citation: How We Localize Surround Sound (2008, January 9) retrieved 18 August 2019 from https://phys.org/news/2008-01-localize.htmlcenter_img Genetic hearing loss may be reversible without gene therapy You’re walking down a busy street, with cars and buses driving past and bits of conversations reaching your ears, when you hear someone call your name. You turn about 60 degrees to your left and look up to the second floor window of a building about 100 meters away, to exactly the spot where a friend is waving. 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Superconductor magnet spacecraft heat shield being developed

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (PhysOrg.com) — European space agencies and an aerospace giant are developing a new re-entry heat shield that will use superconductor magnets to generate a magnetic field strong enough to deflect the superhot plasma formed during re-entry of returning spacecraft. They plan to test the new technology by attaching a test module to a missile and using a Russian submarine to fire it into space. Citation: Superconductor magnet spacecraft heat shield being developed (2009, November 26) retrieved 18 August 2019 from https://phys.org/news/2009-11-superconductor-magnet-spacecraft-shield.html Explore furthercenter_img It’s definite now: Solar sail spacecraft lost As spacecraft re-enter the Earth’s atmosphere at high speeds super-hot temperatures are produced through friction. Traditional heat shields use temperature-resistant ablative coatings that burn off on re-entry, or tough insulating materials, such as the tiles used on the space shuttle. If the new magnetic shielding is successful it could be more reliable and make the craft lighter and easier to re-use, since it would reduce or eliminate the need for other shielding materials.The project is being run cooperatively by the European Space Agency, EADS Astrium, and the German aerospace center, DLR (Deutschen Zentrums for Luft- und Raumfahrt). The idea is to use a superconducting coil at front of the craft to generate a strong magnetic field projecting beyond the front of the craft.The scientists are currently assessing the superconducting coil’s performance, and have not yet finalized the technical details of exactly how they will fit it into a Russian “Volan” escape capsule for the test. Also uncertain at this stage are the modifications that will be needed to the trajectory to compensate for the deflected air. Telemetry data recovery will also present challenges because the ionized gases that will form around the craft will block radio signals.The Volan and its magnetic heat shield would be launched into a suborbital trajectory from a Russian submarine at sea. The missile, a modified ballistic missile called Volna, would re-enter the Earth’s atmospher at Mach 21 and come back to Earth in the Kamchatka peninsula, a remote region of the Russian Far East.Detlev Konigorski of EADS Astrim, speaking in Manchester last month at the 2009 European air and space conference, said he expected the test to take place three years after it is approved, and that should be some time in the next decade.More information: www.flightglobal.com/landingpage/eads.html© 2009 PhysOrg.comlast_img read more

Are some governments taking peak oil seriously

first_img More information: Terry Macalister and Lionel Badal, “Peak oil alarm revealed by secret official talks,” The Observer (August 22, 2010).Stefan Schultz, “‘Peak Oil’ and the German Government,” SPIEGEL ONLINE (September 1, 2010). World crude oil production may peak a decade earlier than some predict Those who contend that peak oil is a very real problem that we need to concerned about push for the development of alternative energy solutions that are renewable, and not in danger of eventual decline. Opponents of the idea of peak oil insist that we are nowhere near any point of decline, and that there is nothing to worry about. Some even call those bring attention to peak oil “alarmists.”However, it appears that some governments are starting to seriously consider the merits of peak oil. Publicly, officials in Britain’s Department of Energy and Climate Change downplay worries about Peak Oil. However, an adviser to the department has requested information about peak oil, and the Guardian reports that there was a peak oil workshop in the not-to-distant past that involved the DECC, Ministry of Defense and the Bank of England. Indications are that some officials in Britain really are considering the possible impacts of peak oil — and thinking about contingency plans should peak oil turn out to be disruptive on an economic and military scale.Britain isn’t the only government interested, either. In Germany, a military study addresses the possible impacts that peak oil could have. A leaked draft of the report by the Bundeswehr Transformation Center was seen by SPIEGEL ONLINE:It warns of shifts in the global balance of power, of the formation of new relationships based on interdependency, of a decline in importance of the western industrial nations, of the “total collapse of the markets” and of serious political and economic crises. While the leaked document was confirmed in its existence, German officials insist that it hadn’t been edited, and that it wasn’t meant to published. Even so, the existence of the report indicates that another government is concerned about the implications that peak oil, if we really are approaching such a point, could have on a worldwide scale.Whether or not you believe that peak oil is a pressing problem, it is interesting to note that some governments are starting to take the issue seriously — and even look for ways to avoid disaster that could come. Image source: Trevor MacInnis via Wikimedia Commons Explore further (PhysOrg.com) — One of the arguments that some bring up in defense of alternative energy is that of “peak oil.” The idea behind peak oil is that, as a fossil fuel in limited supply, eventually we will reach a point where oil production hits its maximum capability — and then begins to decline. Because there aren’t endless supplies of oil, and because it is a finite resource, the idea is that we will reach a tipping point at which it becomes impossible to continue increasing oil production. Some even contend that we’re already there. Citation: Are some governments taking ‘peak oil’ seriously? (2010, September 8) retrieved 18 August 2019 from https://phys.org/news/2010-09-peak-oil.html © 2010 PhysOrg.com This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Is culture or cognition really responsible for language structure

first_img Historical context guides language development More information: Evolved structure of language shows lineage-specific trends in word-order universals, Nature (2011) doi:10.1038/nature09923 Explore further Citation: Is culture or cognition really responsible for language structure? (2011, April 14) retrieved 18 August 2019 from https://phys.org/news/2011-04-culture-cognition-responsible-language.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.center_img (PhysOrg.com) — Linguistic study has been, for many years, divided into two main theories – those following the belief of Noam Chomsky’s universal grammar and that of Joseph Greenberg’s linguistic universal. However, a new study published in Nature by Russell Gray from the University of Auckland shows that neither of these ideas is shown and that language is lineage-specific and not governed by any universals. While Chomsky followers believe that humans are born with an innate ability for language and that grammatical principles are hardwired into the brain and dictate a universal grammar. Joseph Greenberg utilizes a more empirical approach and looks are word order shared by languages.Gray and his colleagues utilized phylogenetic methods to examine the four major language families (Austronesian, Indo-European, Bantu, and Uto-Aztecan) and eight different word-order features. They began by building language family trees from basic vocabulary data to use for testing hypotheses and links between them. They took the different word-order features and mapped them on to the language trees to look for evidence of co-evolution.Their major finding was that features of word-order correlate in many different ways that vary between language families. Even when the researchers found common traits within two different families, they could show that each family arrived at these traits in a different way. Because the linkages are family-specific, it suggests that language structure is not ruled by an innate ability for language or a desire to create a specific word order. Results show that language structure evolves through exploration and is a product of cultural evolution. © 2010 PhysOrg.comlast_img read more

Australopithecus Sediba could be direct ancestor of Homo

first_img Explore further The cranium of Malapa Hominid 1, Holotype of Australopithecus sediba from South Africa. Photo by Brett Eloff, courtesy Lee Berger and the University of the Witwatersrand. Image: Profberger, Brett Eloff, University of the Witwatersrand This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. At the annual meeting of the Paleoanthropology Society on April 12 and again on April 16 at the annual meeting of the American Association of Physical Anthropologists, Berger and his team presented new findings on their most recent bone analysis. Kristian J. Carlson discussed the size and shape of A. sediba’s brain, showing that by synchrotron scanning of the interior brain case, they were able to determine the estimated capacity to be around 420 cubic centimeters. This led to a very small brain size and is the reason researchers first determined these new skeletal findings to be in the Australopithecus genus. However, they also discovered that the frontal lobe of this small brain contained organization more similar to that of humans, showing that contrary to what was previously thought, organization and brain size with human characteristics may not have been a simultaneous change.The pelvis of the A. sediba is what researchers believe show the strongest link toward the beginning of an evolutionary change to the Homo. Researchers have always linked the larger brain size of the Homo to the evolutionary change in the pelvic structure between the two. However, even with the small brain size and cranial structure of A. sediba, the pelvic structure has changed from previous Australopithecus to much closer to that of Homo. © 2010 PhysOrg.com More information: en.wikipedia.org/wiki/Australopithecus_sediba (PhysOrg.com) — Last year Lee Berger from the University of the Witwatersrand and his team discovered the skeletal remains of two specimens they determined to be a new species of human called Australopithecus sediba. The skeletons had characteristics of previous species of Australopithecus, but also of Homo, leading the researchers to believe they may have found an evolutionary connection between the two. This became a very controversial idea, with many believing there was no connection to Homo and that what they had discovered was really an ancestor of later Homo species. Citation: Australopithecus Sediba could be direct ancestor of Homo (2011, April 20) retrieved 18 August 2019 from https://phys.org/news/2011-04-australopithecus-sediba-ancestor-homo.html Family tree branches outlast_img read more

PHD Comics hits the big screen

first_img © 2011 PhysOrg.com Explore further For the last year, grad students around the world have found themselves missing their regular comics, it now appears that creator Jorge Cham had a very good reason for the comic going MIA. He has been working with a team of grad students from California Institute of Technology, or Caltech, to create a live-action film where the characters of his comic strip come alive.Physorg.com spoke with Jorge Cham and learned that the movie was produced and directed by real-life graduate students from Caltech and the comic characters have been brought to life, not by professional actors, but grad students as well. The movie also features cameos by top scientists and professors including two MacArthur “Genius” Award winners.For those of you not familiar with the comic, it focuses on the lives of Cecilia, Mike Slakenerny, Tajel and the Nameless Grad Student. The comic and now the film, looks at the everyday life of a grad student. From research and more research to teaching, friendships and love, the movie presents young scientists as interesting characters and introduces the average person into what life is really like for a grad student.PHD Movie TrailerTelevision shows like the Big Bang Theory have increased the popularity of the scientist in recent years. While the Big Bang Theory is not completely true to life, the hopes of shows like this and of the new PhD Comic movie is to break the old stereotypical view of scientists. Starting September 15, the PhD Comic movie, “Piled Higher and Deeper” The Movie, is being screened worldwide on hundreds of academic campuses and Cham says they plan to send the movie to numerous film festivals as well. To see if the movie will be playing at a campus near you, check out his website for times and locations. (PhysOrg.com) — If you are a graduate student, you are more than likely aware of the popular Piled Higher and Deeper, or PHD, Comics created by Jorge Cham. These comics cover the everyday struggles that scientists face while in grad school in a humorous and accurate depiction. Citation: PHD Comics hits the big screen (2011, September 16) retrieved 18 August 2019 from https://phys.org/news/2011-09-phd-comics-big-screen.htmlcenter_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Facebook founder fodder for animated film (c) Jorge Chamlast_img read more

ZZFS team says file syncs can be more personal

first_img(PhysOrg.com) — Turn over tweaks, updates, and edits on your entire body of recent work, personal accounts, financial records, and legal communiqués to cloud services? Giants like Google might sport a smiley face if you do, but finding an alternative for home PC users has been a topic for researchers. A combined team from Carnegie Mellon and Microsoft Labs in Cambridge, England, have developed ZZFS, a system in prototype of software and hardware that would allow users to access files remotely, even when that home PC is sleeping. A user could use the Windows Explorer file browser to see all the files and folders on other computers with ZZFS installed. Data on one computer would be visible and accessible from any of the others. The file synching system is viewed as an alternative to trusting a third party with files. Whether using Microsoft Office or iTunes, this idea has files opened normally once retrieved over the Internet. Michelle Mazurek of Carnegie Mellon University presented the prototype at the Usenix File and Storage Technology conference in San Jose earlier this month, where sessions and presentations were all about storage-system research and newer directions. The title of the paper, “ZZFS: A hybrid device and cloud file system for spontaneous users”According to a report from Technology Review, the USB device Somniloquy is used along with the software to process network traffic autonomously. As the name suggests, the hardware device connects to the Internet, can awaken a PC from sleep mode, retrieve data and then power it back down. It has enough gigabytes of storage to cache the files. According to the authors of the study, “Somniloquy is more appropriate than Wake-onLAN (WoL) for mobile storage devices, because it operates through firewalls and NAT boxes, and it handles mobility across subnets.”The authors note that “Good execution of data placement, caching and consistency policies across a user’s personal devices has always been hard. Unpredictable networks, capricious user behavior with leaving devices on or off and non-uniform energy-saving policies constantly interfere with the good intentions of a storage system’s policies.”Their goal has been to find a way to better manage the “uncertainties.” They refer to their system as a distributed device and cloud file system for file access. More information: research.microsoft.com/pubs/15 … 1/ZZFSfinalpaper.pdf © 2011 PhysOrg.com Explore furthercenter_img Microsoft ‘streaming storage’ patent maps OS future Citation: ZZFS team says file syncs can be more personal (2012, February 23) retrieved 18 August 2019 from https://phys.org/news/2012-02-zzfs-team-syncs-personal.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Making a molecular micromap Imaging the yeast 26S proteasome at nearatomic resolution

first_img Dr. Friedrich Förster relates the main challenges the researchers faced to Phys.org, starting with achieving automated single particle acquisition. “The aim of automated single particle acquisition is to collect large amounts of high-quality electron micrographs,” Förster begins. “The microscope settings need to be kept essentially invariable over a period of several days, which requires constant adjustment of imaging parameters.” These key parameters, he explains, are image defocus (electron micrographs are not acquired exactly in focus, but with a chosen defocus of typically 1-3 micrometers), eucentric height (an electron microscopy grid is fairly “bumpy” on a micrometer scale, which needs to be compensated for by vertically adjusting the height of the specimen), and illumination settings (lens currents vary to some extent over time, yielding illumination variations that need to be corrected for). “Moreover, “Förster adds, “it needs to be ensured that the whole EM grid is covered with non-redundant images – which is challenging due to specimen movements – and acquisition of ‘garbage’ needs to be minimized (for example, an EM grid typically contains large areas that are intransparent to the electron beam).”The second challenge, Förster continues, was acquiring the cryo-EM structure of the S. cerevisiae 26S proteasome. “The particular challenge of the 26S proteasome is that it cannot be purified to very high concentrations and homogeneity as it often disassembles into smaller building blocks. Hence, an electron micrograph contains relatively few individual particles and many micrographs need to be acquired.” The next step – using the proteasome map building a near-atomic resolution model – has a different issue. “One challenge is the sheer size of the complex: Overall, 33 different subunits are fitted into the map.” This is a number exceeding almost all other structures studied by cryo-EM single particle analysis with the notable exception of the ribosome. “A further problem is that all models are refined starting from homology models, as opposed to X-ray crystallographic structures of the same proteins in different conformations. Homology models, in particular when the sequence similarity is 30% or lower, typically deviate substantially from the true protein structures. Inaccuracies tend to be particularly large for side-chains. Due to these substantial inaccuracies of the initial models the refinement of the models is cumbersome and requires high scrutiny.” 7.4 Å resolution electron microscope (EM) single particle reconstruction of the Saccharomyces cerevisiae 26S proteasome without imposed symmetry. The density is displayed as an isosurface from two different views, on the right colored according to the local resolution as indicated by the color key. Five different slices from the upper RP (A–E) are shown and compared to the counterparts in the lower RP (A’–E’) by difference images. Copyright © PNAS, doi:10.1073/pnas.1213333109 , Nature (Phys.org)—Biological systems are characterized by a form of molecular recycling – and proteins do not escape this fate. In particular, unneeded or damaged proteins biochemically marked for destruction undergo controlled degradation by having their peptide bonds broken by proteasomes. Recently, scientists at the Max-Planck Institute of Biochemistry in Germany used cryo-electron microscopy (cryo-EM) single particle analysis and molecular dynamics techniques to map the Saccharomyces cerevisiae 26S proteasome. (Cryo-EM is a form of transmission electron microscopy where the sample is studied at cryogenic temperatures, which unlike X-ray crystallography allows researchers to observe specimens in their native environment without the need for staining or fixing. S. cerevisiae is the yeast species commonly known as baker’s or brewer’s yeast.) The researchers then used this map to build a near-atomic resolution structural model of the proteasome. The Max Planck team showed that cryo-electron microscopy allowed them to successfully model the 26S core complex where X-ray crystallography studies conducted over the past 20 years have not. More information: Near-atomic resolution structural model of the yeast 26S proteasome, PNAS September 11, 2012 vol. 109 no. 37 14870-14875, doi:10.1073/pnas.1213333109 1Related: Enhancement of proteasome activity by a small-molecule inhibitor of USP14, Nature 467, 179–184 (09 September 2010), doi:10.1038/nature09299 How cells dispose of their waste Another issue is using the map to assign α-helices throughout the entire map, “The assignment of α-helices results from the molecular dynamics-based flexible fitting,” Förster notes. “We estimate our model to be very reliable for α-helical segments, which are well-resolved in the EM map, whereas accuracy is lower for other parts of the models. Luckily, the 26S proteasome consists mostly of helices.”Yet another issue was determining the architecture of the Rpn8/Rpn11 heterodimer, which was entirely unknown prior to their study. “To determine its architecture it was essential to reconstruct the 26S without symmetry, since this symmetry does not seem to apply to high resolution,” Förster points out. “This resulted in a reconstruction with sufficient resolution to localize secondary structure elements in this specific area of the 26S holocomplex.”Interestingly, Förster adds that in this work they did not develop new methodology. “Rather, we applied existing methodology from different areas – data acquisition, single particle reconstruction, and computational modeling – and combined them in an efficient pipeline. Probably, the key insights that we got from this work is the structural organization of the proteasome lid – namely, that it’s held together by a large helical bundle – and how the deubiquitylating site of Rpn11 is positioned at the mouth of the AAA-ATPase.” Deubiquitylating enzymes (DUBs) can hydrolyze a peptide, amide, ester or thiolester bond at the C-terminus of ubiquitin (UBIQ), including the post-translationally formed branched peptide bonds in mono- or multi-ubiquitylated conjugates.Moving forward, Förster tells Phys.org, there are a number of innovations they would like to apply to the current experimental design. “It would be desirable to improve the resolution of the 26S cryo EM map further to improve the accuracy of our model,” he illustrates. “Key to this improvement will be to tackle two things: the structural heterogeneity of particles –different structural modes underlie the observations – and removal of non-informative particles from datasets, since for not entirely understood reasons many particles make reconstructions worse rather than better).” For further data analysis they plan to integrate more elaborate classification methods to address these issues.”After having obtained a first draft of the 26S proteasome structure,” Förster continues, “the next big challenge is to understand how it works. In-depth analysis of the different conformational states that are present in our dataset will provide some clues to the conformation space. Cryo-EM studies of the 26S proteasome engaged with substrates and different biochemical and chemical treatments will then provide more specific insights into the structural reorganizations of the 26S proteasome during its functional cycle.”Förster also mentions the other areas of research that might benefit from their findings. “Firstly, our results will be of great interest to scientists working on the ubiquitin-proteasome pathway, the most important route for regulated protein degradation in all eukaryotic cells. For example,” he illustrates, “the model will be invaluable to interpret data on the assembly process of the 26S proteasome and to study interactions of the 26S proteasomes with other molecules.” Moreover, he points out, the 26S proteasome important as a drug target: The proteasome inhibitor Velcade is a successful anti-cancer drug, and the proteasome is also a promising target of drugs against neurodegenerative diseases1. “Therefore, the 26S proteasome structure,” Förster concludes, “will also be of interest to pharmaceutical and medical scientists.”center_img Copyright 2012 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Journal information: Proceedings of the National Academy of Sciences Citation: Making a molecular micromap: Imaging the yeast 26S proteasome at near-atomic resolution (2012, September 24) retrieved 18 August 2019 from https://phys.org/news/2012-09-molecular-micromap-imaging-yeast-26s.html Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

New research suggests perovskite as cheaper replacement for siliconbased solar panels

first_img Simply meeting the same efficiency levels as silicon isn’t a big deal of course, other materials have been found that are capable of doing so as well, what’s newsworthy here is that using perovskite to make solar cells would be far cheaper. Not only is it more readily available, but it doesn’t require as much production cost. Also, cells that use it would require far less material. Silicon cells, for example, typically wind up approximately 180 micrometers thick. A comparable cell made using perovskite on the other hand would be just 1 micrometer thick.Perovskite isn’t some newly discovered material—scientists have known about it for over 170 years. What’s new is that researchers are only now beginning to fully realize its potential as a material for use in solar cell technology. It was only in 2009 that researchers first thought of using the semiconductor in such cells—initial testing indicated that it was only 3.5 percent efficient. Worse, it didn’t hold up for very long when used. But since that time, researchers have figured out how to make it last longer and have continuously improved its efficiency to boot.Current prototypes are made using a process that involves spraying the material on a base, which means the material is far more versatile than silicon as well. But what really has researchers exited are expectations for creating solar panels far more cheaply than can be done today—estimates suggest they could cost just 10 to 20 cents per watt, as compared to 75 cents per watt for traditional silicon based panels—fossil fuels cost an average of 50 cents per watts, suggesting that the use of perovskite could cause a dramatic shift to solar power in the future if its efficiency can be improved as researchers hope. More information: Oxford Photovoltaics: www.oxfordpv.com/photovoltaic-cell-technology.htmlvia MIT Tech Review This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Dye-sensitized solar cells rival conventional cell efficiency © 2013 Phys.orgcenter_img (Phys.org) —Researchers at Oxford Photovoltaics and other companies investigating the use of perovskite—a crystalline organometal—as a replacement for silicon in photovoltaic cells have created prototypes that are approximately 15 percent efficient. But this is apparently just the beginning. Kevin Bullis suggests in an article published this week in MIT Technology Review, that researchers are predicting efficiencies as high as 25 percent very soon, putting the material on a par with silicon. Citation: New research suggests perovskite as cheaper replacement for silicon-based solar panels (2013, August 16) retrieved 18 August 2019 from https://phys.org/news/2013-08-perovskite-cheaper-silicon-based-solar-panels.html Explore furtherlast_img read more

Researchers use DNA strands to build decomposable nanostructures

first_img Journal information: Nature Nanotechnology Nanostructures made of DNA strands can encapsulate, release small-molecule drugs More information: DNA assembly of nanoparticle superstructures for controlled biological delivery and elimination, Nature Nanotechnology (2014) DOI: 10.1038/nnano.2013.309AbstractThe assembly of nanomaterials using DNA can produce complex nanostructures, but the biological applications of these structures remain unexplored. Here, we describe the use of DNA to control the biological delivery and elimination of inorganic nanoparticles by organizing them into colloidal superstructures. The individual nanoparticles serve as building blocks, whose size, surface chemistry and assembly architecture dictate the overall superstructure design. These superstructures interact with cells and tissues as a function of their design, but subsequently degrade into building blocks that can escape biological sequestration. We demonstrate that this strategy reduces nanoparticle retention by macrophages and improves their in vivo tumour accumulation and whole-body elimination. Superstructures can be further functionalized to carry and protect imaging or therapeutic agents against enzymatic degradation. These results suggest a different strategy to engineer nanostructure interactions with biological systems and highlight new directions in the design of biodegradable and multifunctional nanomedicine.Press release © 2014 Phys.org Explore further DNA can mediate the assembly of nanoparticles and polymers into multifunctional superstructures and control their interactions with biological systems, potentially allowing for applications in cancer imaging and drug delivery while mitigating the risks of toxicity associated with engineered nanomaterials. Credit: Leo Chou, Kyryl Zagorovsky, Warren Chancenter_img (Phys.org) —A team of researchers in Canada has found a way around the problem of large nanostructures that are used to combat tumors, remaining in the body after they are no longer needed. In their paper published in the journal Nature Nanotechnology, the team describes a technique they developed where they used DNA strands to tie together small nanostructures creating larger nanostructures, that over time—after a tumor had been reduced—broke down and left the body. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Researchers use DNA strands to build decomposable nanostructures (2014, January 27) retrieved 18 August 2019 from https://phys.org/news/2014-01-dna-strands-decomposable-nanostructures.html Over the past several years, researchers have discovered that nanostructures, built from nanoparticles can be used to deliver drugs directly to a tumor, killing it. This is preferential to chemotherapy because it harms only tumor cells, rather than healthy cells throughout the body. The down side is that the nanostructures are made of materials that are considered toxic if they build up in the body and worse, are a little too big for the body to break down and get rid of. Thus, the nanostructures remain after they are no longer needed. To get around this problem, the researchers took a very unique approach, they used DNA strands to tie small nanostructures together, creating a large enough structure to transport tumor killing drugs. But because they are tied together with DNA, they become untied as the body breaks down the DNA strands. Once loosed, the nanostructures revert back to groups of smaller structures which the body can process and get rid of.The concept was tested in mice, and results thus far indicate that the process worked as planned—the team was able to actually see the nanostructures as they appeared in the mouse urine, proving that the mice’s systems were able to remove the smaller sized nanostructures from the tumor site and pass them through to the renal system. The researchers report that their technique at this time shows promise, but of course, more work will have to be done to prove that the technique is safe, and that the nanostructures can hold together long enough to do their job. They believe their work will lead to new types of cancer killing agents, but they won’t be ready for use in humans for at least five to ten years.last_img read more