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Thread: Living in a material world

  1. #1

    Living in a material world

    http://web.mit.edu/newsoffice/2013/m...ency-0404.html



    Report finds materials manufacturers will likely be unable to meet targets for carbon-emissions reductions by 2050.

    A new report by researchers at MIT and elsewhere finds that the global manufacturing sector has made great strides in energy efficiency: The manufacturing of materials such as steel, cement, paper and aluminum has become increasingly streamlined, requiring far less energy than when these processes were first invented.


    However, despite more energy-efficient manufacturing, the researchers found that such processes may be approaching their thermodynamic limits: There are increasingly limited options available to make them significantly more efficient. The result, the team observed, is that energy efficiency for many important processes in manufacturing is approaching a plateau.

    The researchers looked at how materials manufacturing might meet the energy-reduction targets implied by the Intergovernmental Panel on Climate Change, which has suggested a 50 percent reduction in carbon-dioxide emissions by 2050 as a means of avoiding further climate change. Meanwhile, economists have estimated that global demand for materials will simultaneously double.

    To reduce energy use by 50 percent while doubling the output of materials, the team — led by graduate student Sahil Sahni and Tim Gutowski, a professor of mechanical engineering at MIT — studied whether manufacturing processes could improve in efficiency by 75 percent. The researchers identified the five most energy-using materials produced, and outlined scenarios in which further energy may be saved in manufacturing. But even in the most aggressive scenario, the team found it was only able to reduce energy use by about 50 percent — far short of its 75 percent goal.

    “What we’re saying is, when you look really big, at global targets for limiting climate change, we think this appears to be beyond what industry can do by itself,” says Gutowski, who leads MIT’s Environmentally Benign Manufacturing research group. “If industry can’t meet these goals, we may need bigger cuts in other sectors.”

    The researchers published their results in the Philosophical Transactions of the Royal Society. Their co-authors are Julian Allwood and Michael Ashby, of Cambridge University, and Ernst Worrell of Utrecht University in the Netherlands.

    Even an optimistic scenario is not enough

    To assess the potential for energy reduction in manufacturing, Gutowski and his colleagues first identified the five materials whose production consumes the most energy. These materials — steel, cement, paper, plastics and aluminum — represent roughly half of energy used and more than half of carbon dioxide emitted in the manufacturing sector. The researchers then identified the most energy-intensive processes involved in manufacturing each of these materials, and looked for ways in which these processes might be made more efficient.

    For example, the team looked for the best available technologies associated with materials manufacturing. According to Gutowski, “There is a distribution of how efficient these operations are around the world.” Some facilities may adopt the most efficient (and expensive) equipment, while others retain older, energy-inefficient processes.

    “These are huge facilities, and very capital-intensive,” Gutowski says. “When you build one, you don’t want to scrap the whole thing and build a new one. So they stay in place for a long time.”

    The researchers drew up an optimistic scenario in which every manufacturing facility adopts the best available technologies. The team disregarded cost — in reality, often a huge barrier to installing energy-efficient processes. Instead, the researchers looked for any solution that may improve energy efficiency by 75 percent — but found they were unable to reach even half of that value

    The team then tried another tactic, looking to reduce energy-intensive processing through wider adoption of recycling; it requires far less energy to recycle a material than it does to manufacture it from scratch. However, they found limits in the supply of recyclable materials, particularly in developing countries that are growing at high rates.

    What about substituting materials such as concrete for steel, or steel for aluminum? The team observed that such changes might save money, as less energy-intensive materials are often also cheaper. But the properties of the substituted materials differ, leading to very different designs, so the comparisons are not straightforward. And in general, Gutowski notes, the trends are actually in the opposite direction: “We are substituting more energy-intensive materials for the less energy-intensive.”

    In the end, the group found that the manufacturing sector as a whole would only be able to reduce its energy use by about 50 percent. A major constraint, Gutowski says, is the materials’ thermodynamic limit: the minimum energy required to manufacture a material from raw inputs. Manufacturers have already made great strides and the best available technologies are now approaching these limits, particularly for the five materials studied — making it difficult, and costly, to achieve further gains.

    Making strides without hurting too much

    Despite these limitations, Gutowski says these gains should be pursued and that there remain additional ways to reduce energy consumption. For example, materials can be made to last longer, or to serve more people. Both scenarios may serve to reduce demand, and hence energy use and carbon emissions.

    John Sutherland, a professor of environmental and ecological engineering at Purdue University, sees the group’s results as a necessary reality check.

    “Just trying to be more efficient in terms of manufacturing is not going to have the impact needed to meet the long-term energy-reduction goals,” says Sutherland, who did not participate in the research. “A fundamental paradigm change does offer promise, [such as] dematerialization — meeting needs through services rather than with material-intensive products.”

    Gutowski says societal actions also play a part in reducing energy use. People may choose to carpool, or take the train, rather than driving their car to work — choices that would improve material efficiency from a broad perspective.

    To date, he says, society hasn’t made as many improvements in energy efficiency as industry. The incentive for industry is to reduce costs; for society to make the same cuts in energy use, different incentives may be needed.

    “I think the game is to get people to do this without it hurting too much,” Gutowski says. “If we put in place incentives, we could probably surprise ourselves at how we might be able to make great strides.”

    Interesting... Thoughts?

    I didn't put this in the climate thread because this is about more than carbon emissions.

  2. #2
    http://web.mit.edu/newsoffice/2013/s...oday-0405.html


    A ‘green’ Sahara was far less dusty than today
    Research points to an abrupt and widespread climate shift in the Sahara 5,000 years ago.

    As recently as 5,000 years ago, the Sahara — today a vast desert in northern Africa, spanning more than 3.5 million square miles — was a verdant landscape, with sprawling vegetation and numerous lakes. Ancient cave paintings in the region depict hippos in watering holes, and roving herds of elephants and giraffes — a vibrant contrast with today’s barren, inhospitable terrain.

    The Sahara’s “green” era, known as the African Humid Period, likely lasted from 11,000 to 5,000 years ago, and is thought to have ended abruptly, with the region drying back into desert within a span of one to two centuries.

    Now researchers at MIT, Columbia University and elsewhere have found that this abrupt climate change occurred nearly simultaneously across North Africa.

    The team traced the region’s wet and dry periods over the past 30,000 years by analyzing sediment samples off the coast of Africa. Such sediments are composed, in part, of dust blown from the continent over thousands of years: The more dust that accumulated in a given period, the drier the continent may have been.

    From their measurements, the researchers found that the Sahara emitted five times less dust during the African Humid Period than the region does today. Their results, which suggest a far greater change in Africa’s climate than previously estimated, will be published in Earth and Planetary Science Letters.

    David McGee, an assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences, says the quantitative results of the study will help scientists determine the influence of dust emissions on both past and present climate change.

    “Our results point to surprisingly large changes in how much dust is coming out of Africa,” says McGee, who did much of the work as a postdoc at Columbia. “This gives us a baseline for looking further back in time, to interpret how big past climate swings were. This [period] was the most recent climate swing in Africa. What was it like before?”

    Getting to the core of dust

    To trace Africa’s dust emissions through time, McGee analyzed sediment samples collected in 2007 by researchers from Columbia and Woods Hole Oceanographic Institution. Researchers sampled from sites off the northwest coast of Africa, spanning a distance of more than 550 miles.

    At each site, they collected a core sample — a 10-foot long cylinder topped by a weight — which scientists submerged, collecting a column of sediment.

    McGee says a 10-foot column represents approximately 30,000 years of sediments deposited, layer by layer, in the ocean — sediments like windblown dust from the continent, marine deposits brought in by ocean currents, and leftover bits of organisms that sank to the seafloor. A centimeter of sediment corresponds to about 100 years of deposition, providing what McGee calls a “high-resolution” record of dust changes through time.

    To trace how much windblown dust accumulated over the past 30,000 years, McGee used a combination of techniques to first determine how fast sediments accumulated over time, then subtracted out the accumulation of marine sediments and biological remnants.

    Layer by layer

    Using a technique called thorium-230 normalization, McGee and his colleagues calculated accumulation rates for sediment layers every two to three centimeters along the column. The technique is based on the decay of uranium in seawater: Over time, uranium decays to thorium-230, an insoluble chemical that sticks to any falling sediment as it sinks to the seafloor. The amount of uranium — and by extension, the production rate of thorium-230 — in the world’s oceans is relatively constant. McGee measured the concentration of thorium-230 in each core sample to determine the accumulation rates of sediments through time.

    In periods when sediments accumulated quickly, there was a smaller concentration of thorium-230. In slower-accumulating periods, McGee measured a greater thorium-230 concentration.

    Once the team calculated rates of sediment accumulation over the past 30,000 years, it went about determining how much of that sediment was dust from neighboring Africa. The researchers subtracted biological sediment from the samples by measuring calcium carbonate, opal and organic carbon, the primary remnants of living organisms. After subtracting this measurement from each sample layer, the researchers tackled the task of separating the remaining sediment into windblown dust and marine sediments — particles that circulate through the ocean, deposited on the seafloor by currents.

    McGee employed a second technique called grain-size endmember modeling, charting a distribution of grain sizes ranging from coarse grains of dust to fine grains of marine soil.

    “We define these endmembers: A pure dust signal would look like this, and a pure marine sediment would look like this,” McGee says. “And then we see, OK, what combination of those extremes would give us this mixture that we see here?”

    This study, McGee says, is the first in which researchers have combined the two techniques — endmember modeling and thorium-230 normalization — a pairing that produced very precise measurements of dust emissions through tens of thousands of years.

    In the end, the team found that during some dry periods North Africa emitted more than twice the dust generated today. Through their samples, the researchers found the African Humid Period began and ended very abruptly, consistent with previous findings. However, they found that 6,000 years ago, toward the end of this period, dust emissions were one-fifth today’s levels, and far less dusty than previous estimates.

    McGee says these new measurements may give scientists a better understanding of how dust fluxes relate to climate by providing inputs for climate models.

    Natalie Mahowald, a professor of earth and atmospheric sciences at Cornell University, says the group’s combination of techniques yielded more robust estimates of dust than previous studies.

    “Dust is one of the most important aerosols for climate and biogeochemistry,” Mahowald says. “This study suggests very large fluctuations due to climate over the last 10,000 years, which has enormous implications for human-derived climate change.”

    As a next step, McGee is working with collaborators to test whether these new measurements may help to resolve a longstanding problem: the inability of climate models to reproduce the magnitude of wet conditions in North Africa 6,000 years ago. By using these new results to estimate the climate impacts of dust emissions on regional climate, models may finally be able to replicate the North Africa of 6,000 years ago — a region of grasslands that were host to a variety of roaming wildlife.

    “This is a period that captures people’s imaginations,” McGee says. “It’s important to understand whether and how much dust has had an impact on past climate.”

    This research was funded by the National Science Foundation and by a National Oceanic and Atmospheric Administration postdoctoral fellowship to McGee.

  3. #3
    http://web.mit.edu/newsoffice/2013/p...-dna-0409.html


    Patterning graphene with DNA
    Folded DNA templates allow researchers to precisely cut out graphene shapes, which could be used in electronic circuits.




    DNA’s unique structure is ideal for carrying genetic information, but scientists have recently found ways to exploit this versatile molecule for other purposes: By controlling DNA sequences, they can manipulate the molecule to form many different nanoscale shapes.

    Chemical and molecular engineers at MIT and Harvard University have now expanded this approach by using folded DNA to control the nanostructure of inorganic materials. After building DNA nanostructures of various shapes, they used the molecules as templates to create nanoscale patterns on sheets of graphene. This could be an important step toward large-scale production of electronic chips made of graphene, a one-atom-thick sheet of carbon with unique electronic properties.

    “This gives us a chemical tool to program shapes and patterns at the nanometer scale, forming electronic circuits, for example,” says Michael Strano, a professor of chemical engineering at MIT and a senior author of a paper describing the technique in the April 9 issue of Nature Communications.

    Peng Yin, an assistant professor of systems biology at Harvard Medical School and a member of Harvard’s Wyss Institute for Biologically Inspired Engineering, is also a senior author of the paper, and MIT postdoc Zhong Jin is the lead author. Other authors are Harvard postdocs Wei Sun and Yonggang Ke, MIT graduate students Chih-Jen Shih and Geraldine Paulus, and MIT postdocs Qing Hua Wang and Bin Mu.

    Most of these DNA nanostructures are made using a novel approach developed in Yin’s lab. Complex DNA nanostructures with precisely prescribed shapes are constructed using short synthetic DNA strands called single-stranded tiles. Each of these tiles acts like an interlocking toy brick and binds with four designated neighbors.

    Using these single-stranded tiles, Yin’s lab has created more than 100 distinct nanoscale shapes, including the full alphabet of capital English letters and many emoticons. These structures are designed using computer software and can be assembled in a simple reaction. Alternatively, such structures can be constructed using an approach called DNA origami, in which many short strands of DNA fold a long strand into a desired shape.

    However, DNA tends to degrade when exposed to sunlight or oxygen, and can react with other molecules, so it is not ideal as a long-term building material. “We’d like to exploit the properties of more stable nanomaterials for structural applications or electronics,” Strano says.

    Instead, he and his colleagues transferred the precise structural information encoded in DNA to sturdier graphene. The chemical process involved is fairly straightforward, Strano says: First, the DNA is anchored onto a graphene surface using a molecule called aminopyrine, which is similar in structure to graphene. The DNA is then coated with small clusters of silver along the surface, which allows a subsequent layer of gold to be deposited on top of the silver.

    Once the molecule is coated in gold, the stable metallized DNA can be used as a mask for a process called plasma lithography. Oxygen plasma, a very reactive “gas flow” of ionized molecules, is used to wear away any unprotected graphene, leaving behind a graphene structure identical to the original DNA shape. The metallized DNA is then washed away with sodium cyanide.

    Shaping graphene circuits

    The research team used this technique to create several types of shapes, including X and Y junctions, as well as rings and ribbons. They found that although most of the structural information is preserved, some information is lost when the DNA is coated in metal, so the technique is not yet as precise as another technique called e-beam lithography.

    However, e-beam lithography, which uses beams of electrons to carve shapes into graphene, is expensive and takes a long time, so it would be very difficult to scale it up to mass-produce electrical or other components made of graphene.

    One shape of particular interest to scientists is a graphene ribbon, which is a very narrow strip of graphene that confines the material’s electrons, giving it new properties. Graphene doesn’t normally have a bandgap — a property necessary for any material to act as a typical transistor. However, graphene ribbons do have a bandgap, so they could be used as components of electronic circuits.

    “There is still interest in using graphene for digital electronics. Graphene itself isn’t ideal for this, but if you pattern it into ribbons, it may be possible,” Strano says.

    Scientists are also interested in graphene rings because they can be used as quantum interference transistors, a novel type of transistor created when electrons flow around a circle. This type of behavior has only recently been observed, and this fabrication technique could allow scientists to create many rings so they can study this phenomenon more thoroughly.

    In the longer term, the DNA nanostructure fabrication strategy could help researchers design and build electronic circuits made of graphene. This has been difficult so far because it’s challenging to place tiny carbon structures, such as nanotubes and nanowires, onto a graphene sheet. However, using the metallized DNA masks to arrange structures on a sheet of graphene could make the process much easier.

    The new approach is “conceptually novel,” says Robert Haddon, a professor of chemical and environmental engineering at the University of California at Riverside, who was not part of the research team. “The work shows the potential of self-assembled metallized DNA nanoarchitectures as lithographic masks for wafer-scale patterning of graphene-based electronic circuit elements. I believe that this approach will stimulate further research on the application of nanopatterning techniques in graphene-based nanoelectronics.”

    The research was funded by the Office of Naval Research, the Defense Advanced Research Projects Agency, the National Science Foundation, and the Army Research Office through the MIT Institute of Soldier Nanotechnologies.



    At left, metallized DNA (red) forms letters on a graphene surface. Treatment with oxygen plasma etches the shape of the letters into the graphene, right.

  4. #4
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    I'm pretty sure the only thing tongs do nowadays is make sure Chinese restaurants don't pay out tips to their waiters. - Pazman[/B]

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  5. #5
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    I'm pretty sure the only thing tongs do nowadays is make sure Chinese restaurants don't pay out tips to their waiters. - Pazman[/B]

    https://scontent-b-pao.xx.fbcdn.net/...8a&oe=52848D36

  6. #6
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    you should check this out. has lots of stuff on Prosthetics.
    http://www.youtube.com/watch?v=eW7Rm2rFW8Y
    I'm pretty sure the only thing tongs do nowadays is make sure Chinese restaurants don't pay out tips to their waiters. - Pazman[/B]

    https://scontent-b-pao.xx.fbcdn.net/...8a&oe=52848D36

  7. #7
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    I'm pretty sure the only thing tongs do nowadays is make sure Chinese restaurants don't pay out tips to their waiters. - Pazman[/B]

    https://scontent-b-pao.xx.fbcdn.net/...8a&oe=52848D36

  8. #8
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    Quote Originally Posted by Syn7 View Post
    http://web.mit.edu/newsoffice/2013/m...ency-0404.html






    Interesting... Thoughts?

    I didn't put this in the climate thread because this is about more than carbon emissions.
    Jevons Paradox

  9. #9
    No need to act out just because you don't have what it takes to understand the article. I'd rather be soulless than barely literate.

    You should give it a shot though. Let us know how many google searches you needed just to understand the terminology.

  10. #10
    Quote Originally Posted by SoCo KungFu View Post
    Jevons Paradox

    Word......


    Rebound effect.
    Last edited by Syn7; 04-09-2013 at 03:02 PM.

  11. #11
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    I'm pretty sure the only thing tongs do nowadays is make sure Chinese restaurants don't pay out tips to their waiters. - Pazman[/B]

    https://scontent-b-pao.xx.fbcdn.net/...8a&oe=52848D36

  12. #12
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    No need to act out just because you don't have what it takes to understand the article. I'd rather be soulless than barely literate.

    You should give it a shot though. Let us know how many google searches you needed just to understand the terminology.
    i bet you have a pocket protector don't you?
    I'm pretty sure the only thing tongs do nowadays is make sure Chinese restaurants don't pay out tips to their waiters. - Pazman[/B]

    https://scontent-b-pao.xx.fbcdn.net/...8a&oe=52848D36

  13. #13
    I'm smiling right now. I finished my work early and rolled up a humongous spliff.


    I use pencil. Pens are annoying and messy. For final draft I use this majik box called com-pu-tor!!! Another useless invention by some soulless scientist.


    Love the stereotype though. Truth is, I can't stand button up shirts. Besides, if I kept pens in a breast pocket they would fly all over place when I'm rocking air flares. You know what air flares are right? It's that thing that gets ya girl wet while she watchin me.

  14. #14
    And we both know you don't have the attention span to actually read the articles. But if you try, let us know how many searches you did. Maybe you can give us a synopsis on each one just to show you understand. I won't hold my breath though.

  15. #15
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    Love the stereotype though. Truth is, I can't stand button up shirts. Besides, if I kept pens in a breast pocket they would fly all over place when I'm rocking air flares. You know what air flares are right? It's that thing that gets ya girl wet while she watchin me.


    And we both know you don't have the attention span to actually read the articles. But if you try, let us know how many searches you did. Maybe you can give us a synopsis on each one just to show you understand. I won't hold my breath though.
    yeah? is that what you would like me to do?
    good thing you can rely on that mental muscle. substitution is a mudda fukka.
    Last edited by hskwarrior; 04-09-2013 at 03:22 PM.
    I'm pretty sure the only thing tongs do nowadays is make sure Chinese restaurants don't pay out tips to their waiters. - Pazman[/B]

    https://scontent-b-pao.xx.fbcdn.net/...8a&oe=52848D36

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