NYPD Goes Green

first_img 40 hybrid patrol cars obviously are not enough to cover all of New York City. However, the city has analyzed the precincts that are most likely to benefit from the hybrid police cars. These precincts include those with large areas of coverage, as well as precincts that may be smaller but sport a great deal of stop and go traffic. The idea is to maximize the benefit of the cars by putting them in areas where the positive environmental gains — and the economic profit — are most evident.The City of New York actually has 3,300 hybrids in service (out of 26,000), but they are mostly assigned to departments that do not see a lot of public safety action: parks and rec, buildings and sanitation. The NYPD will be monitoring these patrol cars to make sure that they are safe and efficient. Hopes are that more hybrid patrol vehicles can be added in the future, helping the NYPD save money on gas. The cost of an Altima, at $25,391, is only a little more than the Crown Victoria ($24,875) and the Chevy Impala ($23,967) also used. As a result, it should be possible for the gas savings from the Altima to more than make up the difference.Also interesting: The Nissan Altima Hybrids are actually made in the U.S.A. The Crown Victorias and Imapalas? Made in Canada.More information: Red, Green and Blue.© 2009 PhysOrg.com Hybrid police cars for the NYPD. Explore further (PhysOrg.com) — New York City has a goal to reduce its overall carbon footprint. For Manhattan, the goal is to reduce greenhouse gases 30% by 2017. As part of this effort, the New York City Police Department just added 40 hybrid cars to its fleet. The Nissan Altima Hybrids are the first NYPD alternative fuel patrol cars, but they probably won’t be the last. The NYPD plans to deploy at least 100 hybrids in total this year. Stop or I’ll download Citation: NYPD Goes Green (2009, May 5) retrieved 18 August 2019 from https://phys.org/news/2009-05-nypd-green.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

California may use vibrational energy of driving to generate power

first_img California bill would put more emphasis on renewable energy (PhysOrg.com) — When you get into your car, for the daily commute or for a relaxing weekend visit to a friend house you give off energy. Not just the energy from the fossil fuels that you burn, but a different kind of energy, vibrational energy. Most of us do not give that energy a second thought, unless we’re trying to do something that requires fine motor skills, such as putting the lid back onto your slightly deformed cup of scalding hot coffee, but it is there. Citation: California may use vibrational energy of driving to generate power (2011, April 27) retrieved 18 August 2019 from https://phys.org/news/2011-04-california-vibrational-energy-power.html It is also a potential source of a green, and renewable energy. California Assemblyman Mike Gatto, a democrat from the Burbank district, hopes to help his home state to use it effectively. He has put in motion a legislation proposing that, if it passes, would create a pilot program designed to capture those vibrations. 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 © 2010 PhysOrg.com Explore further The system, if implemented, would place sensors under a stretch of California roads. These sensors would be able to collect the vibrations caused by traffic and covert them into power. This system, know as piezoelectric generation, has the potential to add significantly to the power supply, if the system were implemented on a larger scale. A potential test patch, a one mile stretch of a two lane highway, would be able to create enough new electricity to power roughly 500 homes for an entire year, or give juice to 120 electrical vehicles each day. Not to mention the powering of street lights and traffic signals.The proposal does not divert funds from any areas, since California regularly sets aside funds for these types of projects. It also would not represent any interruption to the flow of traffic in the state, since the sensors would only be placed under the ground during the regular repaving of roads. No word yet on when this bill will go to a vote or when residents of the state of California can expect to see these changes, should the bill pass in the state legislation.last_img read more

Researchers uncover aerodynamics of the best attributes of the common jump rope

first_img Citation: Researchers uncover aerodynamics of the best attributes of the common jump rope (2011, November 3) retrieved 18 August 2019 from https://phys.org/news/2011-11-uncover-aerodynamics-attributes-common-rope.html For those wondering where they might have heard the name Jeff Aristoff before, he was one of the guys working on the research project last year that cracked the subtle dynamics involved in the way cats drink. At the time he was at Princeton, now working for Numerica Corp, he and Stone sought to find out more about what goes on with jumping rope because it seemed like if they did that, then they might uncover secrets about the aerodynamics of other common things going on in the physical world that haven’t received much attention, and that could conceivably result in new ways to use them. To that end, they used a real life human model, visiting professor Jiang Li, from China, who is really good at jumping rope.To find out what was going on as Li jumped, they attached a high speed camera that allowed them to capture the most subtle movements of the rope as Li jumped. In so doing they were able to watch as the part of the rope farthest from her hands (at the bottom of the U) bent backwards slightly due to it being farther from the points where it was being held, which meant of course that it had to travel faster than the rest of the rope. The reason it bent back was because of having to push through air.Previous studies of rope jumping by others in a vacuum had not seen this. They then put together a rope twirling robot to duplicate what they had observed. Next they filmed the robot doing its thing at high speeds as well, looking in particular at how the rope was impacted by its movement through the air. After that they plugged in everything they had observed into a computer model. Then, by adjusting the size of the rope in the model (its thickness and length) and its weight, they were able to hone their results till they found what they believed to be the traits that led to the optimum jump rope. Thin, lightweight and short.Now that they believe they’ve nailed down all that can be had from studying jump ropes, the team believes their research can be applied in other areas, such engineering projects that involve objects moving through the air or that are subjected to air moving past them; particularly those that have thin components such as suspension bridges. Jump rope aerodynamics More information: The aerodynamics of jumping rope, Published online before print November 2, 2011, Proceedings of the Royal Society A. doi: 10.1098/rspa.2011.0389AbstractWe consider the influence of aerodynamic forces on the shape of a whirling filament that is held at both ends, i.e. a jump rope. At high Reynolds numbers, the rope curls out of the plane and towards the axis of rotation—a feature we demonstrate via experiment. We derive a pair of coupled nonlinear differential equations that characterize the steady-state shape of the rope, and the resulting eigenvalue problem is solved numerically. The solution depends on two dimensionless groups: the ratio between the length of the rope and the distance between its ends, and the relative magnitude of the aerodynamic to centrifugal forces. As the latter ratio is progressively increased, the tension in the rope and the out-of-plane deflection increases, until eventually the rope reaches a limiting shape. Finally, we show that the airflow-induced shape change leads to a relative reduction in drag and has implications for successful skipping. Explore furthercenter_img (PhysOrg.com) — One of the cool things about science is, no matter where you are, it’s all around you, and sometimes all that’s needed is for someone to open their eyes to something that has always just been there. Take jumping rope for example. Jeffrey Aristoff and Howard Stone found themselves wondering one day if the mechanics of the whole operation had ever been studied and worked out. What went on with the rope and what traits made for faster or slower jumping, for example. Last year the two set up a robotic jump rope and filmed the whole process and found that in spite of how things might look to the naked eye, the rope bends out of the plane. Now, a year later, the two have done some more research on the subject and have published their results in Proceedings of the Royal Society A. 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. © 2011 PhysOrg.comlast_img read more

Research duo discover why nonNewtonian fluids harden on impact

first_img © 2012 Phys.org Citation: Research duo discover why non-Newtonian fluids harden on impact (2012, July 12) retrieved 18 August 2019 from https://phys.org/news/2012-07-duo-non-newtonian-fluids-harden-impact.html PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen (Phys.org) — Researchers and laymen alike know that some non-Newtonian fluids tend to harden quickly upon impact. Quicksand is a good example. If a person walks quickly, they won’t sink. But why this happens has been somewhat of a mystery, though many in the science community have suspected it had something to do with energy being transferred to the walls of the container. New research finds that’s not the case at all. Instead, after extensive testing and experimentation Scott Waitukaitis and Heinrich Jaeger of the University of Chicago have found, as they describe in their paper published in the journal Nature, that it’s because the particles suspended in the liquid temporarily mash together, creating a near solid. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen Play Cornstarch and water is a smart material derived from simple components. This video shows a bowling ball bouncing off the surface of the mixture, which also can catch a dropped egg without breaking it. Credit: Heinrich Jaeger/University of Chicago To find out what goes on with oobleck when impacted from above, Waitukaitis set up several different sized tanks of the goo and filmed what happens when a flat bottomed rod strikes its surface from above at varying speeds. He also pointed an x-ray gun at the mix to see what happens underneath the surface and used a laser pointed across the surface to measure how its surface changed when impacted along with a force sensor on the bottom of the tank directly beneath the impact zone. More information: Impact-activated solidification of dense suspensions via dynamic jamming fronts, Nature 487, 205–209 (12 July 2012). doi:10.1038/nature11187AbstractAlthough liquids typically flow around intruding objects, a counterintuitive phenomenon occurs in dense suspensions of micrometre-sized particles: they become liquid-like when perturbed lightly, but harden when driven strongly. Rheological experiments have investigated how such thickening arises under shear, and linked it to hydrodynamic interactions or…See also: Press release 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. Physicists capture microscopic origins of thinning and thickening fluids Play This seven-second video shows a narrow aluminum rod striking the surface of a cornstarch and water mixture at a speed of one meter (3.2 feet) per second. Recorded at 10,000 frames per second with a high-speed camera, the video shows that the rod creates a bowl-like depression around the impact site but fails to penetrate the surface of the fluidic mixture. Credit: Scott Waitukaitis/University of Chicago In studying the results, the two found that the size of the tank didn’t matter as the oobleck hardened the same amount regardless. Thus, theories about energy absorption by the walls accounting for the unusual liquid properties are wrong. Instead they found that the tiny particles that are normally suspended in the liquid are suddenly jammed together when impacted from above, creating a cone like shape inside the liquid that is dense enough to be described as a temporary solid; as it just as quickly dissolves back to its original state. The authors describe the action as akin to snow that is suddenly pushed into a denser state by a plow.The study does answer the major question of why a non-Newtonian liquid hardens, but still a mystery is what happens with the suspended particles when in their hardened state. Do they touch each other or just come close and why do they move apart again after the initial impact? Also, are there differences in hardening as particles get smaller and smaller? Future researchers will no doubt be looking into answering such questions as non-Newtonian liquids might become more useful if their properties become better understood. They might serve as a lighter material in bullet-proof vests for example, or provide a better cushion for people involved in a car crash. Journal information: Nature Non-Newtonian liquids are those that don’t behave as Isaac Newton originally theorized, e.g. quicksand, ketchup, custard, blood, or in the case of the material studied by the research team, a water and cornstarch solution called oobleck.last_img read more

Graphene coating transforms fragile aerogels into superelastic materials

first_img Journal information: Nature Nanotechnology More information: Kyu Hun Kim, et al. “Graphene coating makes carbon nanotube aerogels superelastic and resistant to fatigue.” Nature Nanotechnology. Advance Online Publication. DOI: 10.1038/NNANO.2012.118 As compression increases in this sequence of images, the graphene-coated nanotubes undergo increasing alignment, strengthening the aerogel. Image credit: Kim, et al. ©2012 Macmillan Publishers Limited To overcome this inelasticity problem, the researchers demonstrated that one to five layers of graphene coating enables a CNT aerogel to withstand more than 1 million compressive cycles and return to its original shape after compression release. The ability to withstand this compression turns the aerogels into superelastic materials, while at the same time allowing them to maintain their other properties such as porosity and conductivity.The researchers think that the graphene coating imparts this superelasticity to the aerogel by strengthening the aerogel’s nodes and struts, both of which support the aerogel’s network structure. In non-coated aerogels, the struts can bend and freely rotate about the nodes when compressed, which increases the contact area between nanotubes and forms new nodes. When the load is removed, the new nodes remain since more force is required to remove the nodes than to form them. Citation: Graphene coating transforms fragile aerogels into superelastic materials (2012, August 9) retrieved 18 August 2019 from https://phys.org/news/2012-08-graphene-coating-fragile-aerogels-superelastic.html In contrast, the stronger struts in graphene-coated aerogels cannot easily rotate about the nodes when compressed. Although new nodes are formed in the coated aerogels as well, the graphene coating can remove these nodes when the load is removed.“Both CNT aerogels and graphene-coated CNT aerogels form ‘new’ nodes when compressed,” Islam explained. “We think that the graphene at the nodes gets compressed and crumpled when the graphene-coated aerogels are compressed. When the load is removed, nanotube aerogels do not recover original shape because there is no restorative force to ‘break’ the new nodes that formed during compression. In contrast, the compressed and crumpled graphene flakes provide the restorative force (i.e., act as springs) that is needed to break these new nodes in graphene-coated aerogels.”CNT aerogels that can undergo high levels of compression and later spring back to their original shapes could open the doors to new aerogel applications. CNT aerogels already have attractive features, such as the inherent flexibility of aerogel synthesis that allows researchers to control their shapes and sizes, and superelasticity makes these materials even more attractive.“CNT aerogels, particularly single-walled carbon nanotube (SWCNT) aerogels, have a high surface area, are electrically conducting, have large pores, and have fairly good thermal dissipation properties if you consider that the amount of material in them is really small,” Islam said, adding that his team has recently published papers on the aerogels’ heat transport properties and a surface area close to the theoretical limit. “Because of their properties, CNT aerogels can be used as a scaffold to make composites, sieves, ultralight heat sinks in high gravity applications, electrodes, and catalyst supports. Typically, nanotubes are incompatible with polymers and tend to phase-segregate. By using aerogels as a scaffold and backfilling with polymer, nanotubes can remain well-dispersed in the polymer matrix. This can significantly improve mechanical enhancement.”The researchers are currently investigating other areas of CNT aerogels, in addition to superelasticity.“We are currently working on a few projects,” he said. “We are using SWCNT aerogels to make electrically conducting composites. We are also looking into making mechanically strong polymer composites. With our collaborators, we are exploring the electrochemical properties of SWCNT aerogels. We are growing metal nanoparticles on these SWCNT aerogels for use as filters for remediation of harmful chemicals from water. Also we are using them as porous 3D conducting substrates for tissue growth.“I think the modulus and strength of these nanotube aerogels need to be improved without decreasing the porosity. As you can imagine, the aerogels can be made significantly stronger by just increasing the volume fraction of nanotubes in them but this will reduce the porosity.” Explore further 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. Penn Physicists Develop a Carbon Nanotube Aeroegel Optimizing Strength, Shape and Conductivity After CNT aerogels are compressed and released, the non-coated aerogel collapses while the graphene-coated aerogel recovers its original shape. Image credit: Kim, et al. ©2012 Macmillan Publishers Limited The researchers, Kyu Hun Kim, Youngseok Oh, and Mohammad F. Islam at Carnegie Mellon University in Pittsburgh, Pennsylvania, have published their paper on the mechanical benefits of a graphene coating on CNT aerogels in a recent issue of Nature Nanotechnology.”We demonstrate the transformation of a nanotube network from fragile to superelastic simply via ‘nanocoating,’” Islam told Phys.org. “Typically, coating adds corrosion resistance, lubrication, aesthetics, alteration of surface chemistry, sealing, etc., but not mechanical property change.”While a normal gel consists mostly of liquid material with a cross-linked network that gives it its solid-like structure, an aerogel is created by replacing the liquid material in a gel with a gas. Researchers do this by drying the original gel at a critical temperature. The resulting aerogel is a lightweight material made of 99.9% air by volume, yet one that is also dry, rigid, and strong like a solid.In the current study, the researchers worked with CNT aerogels, which (in addition to the air) are made of dispersed nanotubes about 1 micrometer long. CNT aerogels hold their shape due to molecular interactions at the nodes, the points where the nanotubes cross each other. However, when these aerogels are compressed by up to 90% of their original size, they collapse or become permanently deformed, limiting potential applications. (Phys.org) — Like donning a Superman’s cape, fragile carbon nanotube (CNT) aerogels that are covered by a graphene coating can be transformed from a material that easily collapses under compression to one that can resist large amounts of compression and completely recover its original shape after removal of the load. The superelasticity and fatigue resistance provided by the graphene coating could make CNT aerogels useful in a variety of areas, including as electrodes, artificial muscles, and other mechanical structures. 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

Manipulating Lorentz and Fano spectral line shapes

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. © 2013 Phys.org , arXiv In Fano resonance, interference between a background and a resonant scattering process gives rise to the asymmetric line shape. A theoretical explanation of this process was first given by Ugo Fano, who studied the inelastic scattering of electrons off of helium. It is now a commonly observed phenomenon found in many areas of physics and engineering. In spectroscopy, the observed spectral line positions show the energy levels of excited quantum states, while the line shapes are determined by how the material relaxes after light is absorbed. Controlling this absorption by coupling the material to an intense optical laser has led to unique discoveries like, for example, electromagnetically-induced transparency, and slow or stopped light.Performing these kinds of manipulations in the extreme UV, and soft x-ray frequency regime has been a challenge. Ott and the other researchers were able to show that this kind of control can be extended to inner-shell electrons by tuning the time delay between an extreme UV laser, and an IR laser. Specifically, at a laser intensity of 2TW/cm2, they were able to turn doubly excited asymmetric states into symmetric Lorentzian states. At lower intensities, they were also able to turn symmetric line shapes of singly excited states into asymmetric ones. Their explanation is that in the presence of the NIR laser, additional phase is acquired by the Fano resonances, which changes the line profiles.In general, the Fano resonance line shape is caused by interference between two scattering amplitudes. One is due to scattering within a continuum of background states, and the other due to an excitation of a discrete resonant state. The resonant state energy must be within the energy range of the background state to generate the effect. Near the resonant energy, the amplitude of the background scattering tends to vary slowly with energy, while the resonant scattering amplitude changes quickly both in phase and magnitude. This variation is what creates the asymmetric shape.The researchers only presented data for a fixed time delay. Extending these experiments to many different time delays may be a good follow-up study. Although the experiments here were done in helium gas, the authors note that there is no reason why these mechanisms should not be applicable to molecules, or excitons in condensed phase or mesoscopic materials. A change in the absorption profile can also be interpreted as a measure of an induced phase shift of a complex quantum-mechanical state amplitude in a laser field. With that in mind, numerous applications within spectroscopy and even quantum-state holography may exist in the near future. Flexible design approach for nanosensors that overcomes practicality and reliability issues now available (Phys.org) —It is widely known that the optical properties of certain materials can be modified by using lasers to control the quantum states of their optical electrons. Lasers that can generate ultra-short pulses in the attosecond range at very high power can now be used to probe and control nanostructures like photonic crystals, metal hole arrays, and conductance in quantum dots. The light absorption spectrum of a material reveals critical details about its microstructure. Depending on different factors, this spectrum can take on a symmetric Lorentzian line shape, or an antisymmetric Fano line shape. A new paper in Science now demonstrates that this absorption profile can by changed from a Lorentzian shape, to a Fano shape, by manipulating laser intensity. Led by Christian Ott, from the Max Planck Institut in Germany, the researchers achieved this by co-propagating a broadband UV pulse train with a “few cycle” near-infrared (NIR) beam in a helium target. Fano Resonances. Credit: Wikipedia Commons Explore further More information: Lorentz Meets Fano in Spectral Line Shapes: A Universal Phase and Its Laser Control, Science 10 May 2013: Vol. 340 no. 6133 pp. 716-720. DOI: 10.1126/science.1234407 (On ArXiv: http://arxiv.org/abs/1301.1454 )ABSTRACTSymmetric Lorentzian and asymmetric Fano line shapes are fundamental spectroscopic signatures that quantify the structural and dynamical properties of nuclei, atoms, molecules, and solids. This study introduces a universal temporal-phase formalism, mapping the Fano asymmetry parameter q to a phase ϕ of the time-dependent dipole response function. The formalism is confirmed experimentally by laser-transforming Fano absorption lines of autoionizing helium into Lorentzian lines after attosecond-pulsed excitation. We also demonstrate the inverse, the transformation of a naturally Lorentzian line into a Fano profile. A further application of this formalism uses quantum-phase control to amplify extreme-ultraviolet light resonantly interacting with He atoms. The quantum phase of excited states and its response to interactions can thus be extracted from line-shape analysis, with applications in many branches of spectroscopy.Commentary: www.sciencemag.org/content/340/6133/694.full Journal information: Science Citation: Manipulating Lorentz and Fano spectral line shapes (2013, May 13) retrieved 18 August 2019 from https://phys.org/news/2013-05-lorentz-fano-spectral-line.htmllast_img read more

Flexible allcarbon electronics integrated onto plants insects and more

first_img“Both the carbon nanotubes and graphite are carbon,” he said. “Depending on the bond structure of carbon, the carbon nanotubes can exhibit semiconducting properties and the graphite can show metallic properties. We designed multiple catalysts to synthesize the carbon nanotubes and graphite locally with the desired structures of electronic devices. In this way, the all-carbon devices can be synthesized.”The resulting devices demonstrate good performance, with the transistors operating with a high on-off ratio exceeding 103. To demonstrate the flexibility of the devices, the researchers transferred the sensors directly onto the curved surface of an optical fiber with a radius of 100 µm, where the sensors continued to operate normally. More information: Kyongsoo Lee, et al. “In-situ Synthesis of Carbon Nanotube-Graphite Electronic Devices and Their Integrations onto Surfaces of Live Plants and Insects.” Nano Letters. DOI: 10.1021/nl500513n (Phys.org) —Carbon-based electronics are being widely explored due to their attractive electrical and mechanical properties, but synthesizing them in large quantities at low cost is still a challenge. (a) The CNT-graphite sensor array (left) on a solid surface and (right) floating on water. (b) Photographs of the sensor array transferred onto a fingernail, a particulate mask, a protective arm sleeve, an adhesive tape, and a sheet of newspaper. Scale bars: 1 cm. Credit: Lee, et al. ©2014 American Chemical Society 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 electronic devices can also be integrated onto various surfaces via van der Waals forces. For example, after wetting the transistors and sensors, the researchers showed that they can be attached to the leaf of a live bamboo plant and to the epidermis of a live stag beetle. The researchers also demonstrated that the sensors could be fitted onto the surfaces of a fingernail, a particulate mask, a protective arm sleeve, adhesive tape, and newspaper. The widespread application of all-carbon electronics in outdoor environments could be useful for a variety of reasons. Here the researchers show that the sensors can detect very low levels of DMMP vapor, which is used for producing nerve agents such as soma and sarin. The sensors could also be used to monitor environmental conditions, including temperature, humidity, pollution, and infections. All this can be done without an on-board power source.”We integrated antennas with our devices,” Park said. “Thus, the wireless transportation of power and sensing signals was possible with no battery.”Due to their good adhesion to the nonplanar surfaces of biomaterials, the all-carbon electronics have the potential for use as bioimplantable devices, as well. The researchers plan to further explore the potential applications in the future.”In this paper, we just demonstrated the detection of the nerve gas using the biocompatible devices,” Park said. “As our future research, we will develop various sensing systems, including diabetes, pollutions and radioactivity, using the wearable electronic devices.” Flexible CNT-graphite arrays transferred onto the surface of a live leaf and the surface of a stag beetle. The sensors can be used to detect chemical warfare agents or monitor environmental conditions. Credit: Lee, et al. ©2014 American Chemical Society Journal information: Nano Letters Now in a new study, researchers have developed a new method for synthesizing entire integrated all-carbon electronic devices, including transistors, electrodes, interconnects, and sensors, in a single step, greatly simplifying their formation. The inexpensive electronic devices can then be attached to a wide variety of surfaces, including plants, insects, paper, clothes, and human skin.The researchers, Kyongsoo Lee, et al., at the Ulsan National Institute of Science and Technology (UNIST) in Ulsan Metropolitan City, South Korea, and the Korea Electrotechnology Research Institute in Changwon, South Korea, have published a paper on the new synthesis method in a recent issue of Nano Letters.The new approach takes advantage of the unique atomic geometries of carbon to synthesize entire arrays of electronic devices, specifically carbon nanotube transistors, carbon nanotube sensors, and graphite electrodes. “Our all-carbon devices (transistors and sensors) are composed of (i) carbon nanotubes (as channels) and (ii) graphite (as electrodes),” coauthor Jang-Ung Park, Assistant Professor at UNIST, told Phys.org. “The channel part requires semiconducting materials whose resistance can be sensitively controlled by external bias. The electrode part needs metallic materials whose resistance is very small with the negligible change by external bias.”As Park explained, the different properties of the nanotubes and graphite are due to their different bond structures. Explore further © 2014 Phys.org High-performance, low-cost ultracapacitors built with graphene and carbon nanotubes Citation: Flexible all-carbon electronics integrated onto plants, insects, and more (2014, May 6) retrieved 18 August 2019 from https://phys.org/news/2014-05-flexible-all-carbon-electronics-insects.htmllast_img read more

New fossils show ancient comb jellies had skeleton parts

first_imgFour taxa of Cambrian skeletonized comb jellies. Credit: Dr. Qiang Ou and his colleagues Contrary to popular belief, though they may look a lot like them, comb jellies are not jellyfish, instead they belong to the phylum Ctenophora. Scientists have found over a hundred species of the creature in its modern form and not one of them has any sort of skeleton. That is why the find in China is so surprising, an early relative that lived approximately 520 million years ago (during the Cambrian Period), did have some bony parts.The fossils were found at the famous Chengjiang site, embedded in rock—in all, six species were found among over three dozen specimens, each with some amount of hard skeleton material. The bone-like material was shaped like spokes, struts or plates. The plates appeared to cover the bodies, serving apparently, as a barrier against predators, or perhaps some other harmful environmental factor. The researchers cannot say for sure what the bone-like material was made of but suspect it was likely chitin or something similar, or even a carbonate rich mineral material. Also, because of the arrangement of the spokes or struts, the team suggests that the bones could have served a dual purpose, structural support and as a defense mechanism. In a bit of a twist, if the skeletal parts were indeed meant as a protection mechanisms, it does not appear to have worked out—the fossil species found in the rocks never made it to the modern age, they all died out.The finding also appears to contradict theories (based on DNA models) that have suggested ancient comb jellies had tentacles—none of the fossils had any sign of them. On the other hand, finding they had skeletons suggests they faced unknown threats, which should present a new avenue for study. © 2015 Phys.org More information: A vanished history of skeletonization in Cambrian comb jellies, Science Advances  10 Jul 2015: Vol. 1, no. 6, e1500092. DOI: 10.1126/sciadv.1500092AbstractCtenophores are traditionally regarded as “lower” metazoans, sharing with cnidarians a diploblastic grade of organization. Unlike cnidarians, where skeletonization (biomineralization and sclerotization) evolved repeatedly among ecologically important taxa (for example, scleractinians and octocorals), living ctenophores are characteristically soft-bodied animals. We report six sclerotized and armored ctenophores from the early Cambrian period. They have diagnostic ctenophore features (for example, an octamerous symmetry, oral-aboral axis, aboral sense organ, and octaradially arranged ctene rows). Unlike most modern counterparts, however, they lack tentacles, have a sclerotized framework, and have eight pairs of ctene rows. They are resolved as a monophyletic group (Scleroctenophora new class) within the ctenophores. This clade reveals a cryptic history and sheds new light on the early evolution of this basal animal phylum. Skeletonization also occurs in some other Cambrian animal groups whose extant members are exclusively soft-bodied, suggesting the ecological importance of skeletonization in the Cambrian explosion. Explore further (Phys.org)—A team of researchers with members from several institutions in China and one in the U.S. has found evidence that shows that ancient comb jellies had skeleton parts. In their paper published in the journal Science Advances, the team describes comb jelly ancestor fossils that were found in rock formations in China, the skeleton parts they found and theories regarding possible reasons for those parts.center_img Ancient balloon-shaped animal fossil sheds light on Earth’s ancient seas Citation: New fossils show ancient comb jellies had skeleton parts (2015, July 13) retrieved 18 August 2019 from https://phys.org/news/2015-07-fossils-ancient-jellies-skeleton.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. Journal information: Science Advanceslast_img read more

Underground formations reveal wet past of Australias Nullarbor Plain

first_img(Phys.org)—A team of researchers affiliated with several institutions in Australia has found evidence that suggests that a desert region in Australia experienced a relatively short burst of wetter weather approximately five million years ago. The team has published a paper in Proceedings of the National Academy of Sciences detailing their study of stalagmites and stalactites in caves in the area and why they believe what they found might give a hint of what the future holds for Australia. Explore further Prior research has shown that the Nullarbor Plain, which lies near the southern edge of the middle of the country, has been drying out for approximately 14 million years. It was prior to that time that underground caves formed, capturing, the researchers report, evidence of climate changes.In their study, the researchers looked at stalagmites and stalactites in which minute amounts of pollen had been captured due to air circulating in from aboveground. In studying the pollen and comparing it with the ages of material in which they were embedded, the researchers were able to show that there was a pause in the long slow drying period during which things grew considerably wetter. Approximately five million years ago, they claim, rain in the area increased so much that the area became part of a rain forest. And it happened very quickly, geologically speaking, in a matter of just 100,000 years. That period, the team reports, lasted for approximately two millions years—after that the area returned to its dryer pattern that led to the weather in the area today—the Nullarbor Plain gets just 3cm of rain on average per year.To explain the suddenly wetter conditions, the researchers point to other research that has shown that ocean temperatures rose just prior to the short wet period, and that led to a fourfold increase in rainfall in parts of Australia, which led to a transformation in the types of plants growing in some areas. The oceans warmed, it is believed, due to unknown factors that caused global atmospheric warming. The researchers note that most scientists believe that the Earth will once again become as warm as it was during that period five million years ago, due to man-made causes, and thus, it appears likely parts of Australia are going to get a lot wetter in the not too distant future. Scientists examined fossilised pollen inside stalagmites to shed new light on the Nullarbor’s climate history Geological relics point to Nullarbor climate shift Journal information: Proceedings of the National Academy of Sciencescenter_img More information: Pliocene reversal of late Neogene aridification, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1520188113AbstractThe Pliocene epoch (5.3–2.6 Ma) represents the most recent geological interval in which global temperatures were several degrees warmer than today and is therefore considered our best analog for a future anthropogenic greenhouse world. However, our understanding of Pliocene climates is limited by poor age control on existing terrestrial climate archives, especially in the Southern Hemisphere, and by persistent disagreement between paleo-data and models concerning the magnitude of regional warming and/or wetting that occurred in response to increased greenhouse forcing. To address these problems, here we document the evolution of Southern Hemisphere hydroclimate from the latest Miocene to the middle Pliocene using radiometrically-dated fossil pollen records preserved in speleothems from semiarid southern Australia. These data reveal an abrupt onset of warm and wet climates early within the Pliocene, driving complete biome turnover. Pliocene warmth thus clearly represents a discrete interval which reversed a long-term trend of late Neogene cooling and aridification, rather than being simply the most recent period of greater-than-modern warmth within a continuously cooling trajectory. These findings demonstrate the importance of high-resolution chronologies to accompany paleoclimate data and also highlight the question of what initiated the sustained interval of Pliocene warmth.Press release Citation: Underground formations reveal wet past of Australia’s Nullarbor Plain (2016, February 9) retrieved 18 August 2019 from https://phys.org/news/2016-02-underground-formations-reveal-australia-nullarbor.html © 2016 Phys.org 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

Model suggests 1812 San Andreas earthquake may have been set off by

first_img Citation: Model suggests 1812 San Andreas earthquake may have been set off by San Jacinto quake (2016, March 14) retrieved 18 August 2019 from https://phys.org/news/2016-03-san-andreas-earthquake-jacinto-quake.html 7.5 quake on California fault could be disastrous © 2016 Phys.org Journal information: Science Advances Back in 1812 a major earthquake struck southern California near what is now San Bernardino—modern study of damage from the quake suggested it was approximately a magnitude 7.5 quake. There was little damage because there were few structures in the area back then, though approximately 40 people were killed when a church they were in collapsed. For many years, Earth scientists have assumed that the quake was due solely to activity along the San Andreas Fault. In this new effort, Lozos suggests that the quake may have actually been set off by a quake along the San Jacinto fault line.Lozos’ findings are part of a study that included field trips to several sites in an area where the San Andreas Fault and the San Jacinto Fault nearly merge. While there, he found evidence of three strands—where sections of fault are separated by bits of crust that has remained intact—one near the San Andreas fault and two near the San Jacinto fault. Each strand is evidence of an earthquake, but reports from people in the area suggest there were only two earthquakes during the time period under study—in 1812 and 1800, which suggested that one of the strands on the San Andreas Fault and one on the San Jacinto Fault were evidence of the same quake. Lozos also looked at other data collected by other researchers doing working on faults in the area—all of it went into a model he built to describe seismic activity in the area surrounding the time frame of the 1812 quake. The model showed that the most likely scenario that could account for the data that has been collected was that a quake had occurred along the San Jacinto fault line and as it made its way near the San Andreas fault line, the disruption caused a quake to occur along that fault line as well.Lozos is quick to point out that his model is just that and that thus far he has no evidence to suggest that such a double quake is imminent, but he also notes that if it happened before, it could happen again, noting that southern California is long overdue for a pretty big tumbler. 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 More information: J. C. Lozos. A case for historic joint rupture of the San Andreas and San Jacinto faults, Science Advances (2016). DOI: 10.1126/sciadv.1500621AbstractThe San Andreas fault is considered to be the primary plate boundary fault in southern California and the most likely fault to produce a major earthquake. I use dynamic rupture modeling to show that the San Jacinto fault is capable of rupturing along with the San Andreas in a single earthquake, and interpret these results along with existing paleoseismic data and historic damage reports to suggest that this has likely occurred in the historic past. In particular, I find that paleoseismic data and historic observations for the ~M7.5 earthquake of 8 December 1812 are best explained by a rupture that begins on the San Jacinto fault and propagates onto the San Andreas fault. This precedent carries the implications that similar joint ruptures are possible in the future and that the San Jacinto fault plays a more significant role in seismic hazard in southern California than previously considered. My work also shows how physics-based modeling can be used for interpreting paleoseismic data sets and understanding prehistoric fault behavior. Records of the December 1812 earthquake in southern California. Credit: Lozos Sci. Adv. 2016; 2 : e1500621 Explore further (Phys.org)—An assistant researcher professor with California State University has found evidence that the powerful quake that struck southern Californian back in 1812 may have been precipitated by a fault line other than the San Andreas. In his paper published in the journal Science Advances, Julian C. Lozos describes a computer model he created using real world data, what it showed, and why his findings suggest that a future double earthquake could occur someday in the area.last_img read more

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