nanoscience

Polymer mold makes perfect silicon nanostructures

Using molds to shape things is as old as humanity. In the Bronze Age, the copper-tin alloy was melted and cast into weapons in ceramic molds. Today, injection and extrusion molding shape hot liquids into everything from car parts to toys.

For this to work, the mold needs to be stable while the hot liquid material hardens into shape. In a breakthrough for nanoscience, Cornell polymer engineers have made such a mold for nanostructures that can shape liquid silicon out of an organic polymer material. This paves the way for perfect, 3-D, single crystal nanostructures.

The advance is from the lab of Uli Wiesner, the Spencer T. Olin Professor of Engineering in the Department of Materials Science and Engineering, whose lab previously has led the creation of novel materials made of organic polymers. With the right chemistry, organic polymers self-assemble, and the researchers used this special ability of polymers to make a mold dotted with precisely shaped and sized nano-pores.

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Nanomedicine

In a 1959 lecture at Caltech famously dubbed “There’s Plenty of Room at the Bottom,” American physicist and Nobel laureate–to-be Richard Feynman discussed the idea of manipulating structures at the atomic level. Although the applications he discussed were theoretical at the time, his insights prophesied the discovery of many new properties at the nanometer scale that are not observed in materials at larger scales, paving the way for the ever-expanding field of nanomedicine. These days, the use of nanosize materials, comparable in dimension to some proteins, DNA, RNA, and oligosaccharides, is making waves in diverse biomedical fields, including biosensing, imaging, drug delivery, and even surgery.

Nanomaterials typically have high surface area–to-volume ratios, generating a relatively large substrate for chemical attachment. Scientists have been able to create new surface characteristics for nanomaterials and have manipulated coating molecules to fine-tune the particles’ behaviors. Most nanomaterials can also penetrate living cells, providing the basis for nanocarrier delivery of biosensors or therapeutics. When systemically administered, nanomaterials are small enough that they don’t clog blood vessels, but are larger than many small-molecule drugs, facilitating prolonged retention time in the circulatory system. With the ability to engineer synthetic DNA, scientists can now design and assemble nanostructures that take advantage of ?Watson-Crick base pairing to improve target detection and drug delivery.

Both the academic community and the pharmaceutical industry are making increasing investments of time and money in nanotherapeutics. Nearly 50 biomedical products incorporating nanoparticles are already on the market, and many more are moving through the pipeline, with dozens in Phase 2 or Phase 3 clinical trials. Drugmakers are well on their way to realizing the prediction of Christopher Guiffre, chief business officer at the Cambridge, Massachusetts–based nanotherapeutics company Cerulean Pharma, who last November forecast, “Five years from now every pharma will have a nano program.”

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This microscopic pyramid is actually a cage for a living cell, constructed to better observe cells in their natural 3D environment, as opposed to the usual flat plane of a Petri dish. Researchers from the University of Twente in the Netherlands made the cage by depositing nitrides over silicon pits. When most of the material is peeled away, a small amount of material remains in the corners to create a pyramid. Because the pyramids have holes in the sides and are close together, the cells can interact for the most part as they naturally do.

By Berenschot, E., et al. at the University of Twente, Netherlands

He might not have a corncob pipe and a button nose, but a microsnowman recently fabricated by David Cox, a scientist in the Quantum Detection group at the National Physical Laboratory, in the U.K., has something Frosty doesn’t: staying power. Made of two tin beads “glued” together with a bit of platinum, this snowman stands about 25 μm high and doesn’t fear the sun, permanently smiling with a mouth milled out by a focused ion beam (FIB).

According to Cox, his jolly little creation, which stands atop an atomic force microscope cantilever, was put together for the lab’s annual holiday card. But images and video of the “world’s smallest snowman” also went viral over the Web. “It has certainly given me an insight into the power of the Internet,” he tells C&EN. “I’ve had colleagues all over the world asking it if was mine.”

Cox typically uses the lab’s dual-beam FIB instrument to make or modify objects such as nano-superconducting quantum interference devices (nanoSQUIDs) for studying the nanomagnetism of biological systems. To make the snowman, he used the instrument’s piezo manipulation system and a carbon-fi ber tip to move the beads into place. He then deposited the platinum glue through ion-beam decomposition of a short burst of (CH3)3(CH3C5H4) Pt gas. The snowman’s nose, about 1 μm wide, is also a small blob of platinum, deposited in mere seconds. “I only had a couple of days to plan it and build it, so I decided on the snowman,” Cox says. “I could put it together in a couple of hours.” But “had I known it would go global,” he laments, “I would have made it much smaller—at least an order of magnitude.”

-Lauren K. Wolf

Newscripts: Walkin’ in a winter nanoland

Chemical & Engineering News, January 4, 2010

When we want to “see” the structure of a material on the nanoscale - where the distance between atoms is just one billionth of a meter - we use an x-ray beam to give us an idea of where each atom is located.

That mesmerizing arc in the image above is called an x-ray diffraction pattern. When you beam x-rays at a crystal, they bounce off atoms in the structure at different angles. The location and brightness of the red spots are where the x-rays landed after angling away from the sample they encountered. Then, our scientists use customized mathematical models to piece together the data and get an idea of the structure within a material.

The way you set up your experiment can tell you different traits of the materials you’re probing, says staff scientist Kevin Yager at Brookhaven’s Center for Functional Nanomaterials (CFN).

“There are many different kinds of x-ray scattering experiments, tuned to probe different structures at different scales. For instance, wide-angle scattering can reveal molecular structure, molecular packing, and atomic spacing, while small-angle scattering can address nanoscale structure, phase separation of polymers, lithographic patterns, particle orientations, and so on.” 

Kevin and his colleagues employ x-rays using several different techniques at our National Synchrotron Light Source to determine what’s going on inside catalysts and other materials built or grown at the CFN. When our new light source begins beaming x-rays in 2015, the higher energy and focusing capability of the beam will make it possible to shine light on things that may never have been seen before. 

As we learn more about what’s going on inside catalysts for future energy sources or new kinds of batteries, we’ll find ourselves staring into these beautiful diffractions patterns. Go on, get lost in there with us. 

Rigid, donut-shaped molecules form self-assembling organic nanotubes. The tubes contain a non-deformable sub-nanometer pore. The availability of these structurally simple, synthetic nanopores with adjustable diameters could carve a new path for fabrication of highly efficient, practical membranes for applications ranging from water purification to molecular separations. Credit:Bing Gong, SUNY-Buffalo

anonymous asked:

What's the largest sheet of Graphene ever made? (Was it a Graphene sheet they held up during the Nobel prize ceremonies a few years back?)

This is a bit of a thorny issue actually and the answer depends on how much of a purist you are.

Graphene, as you may know, is a single layer sheet of carbon atoms in a honeycomb arrangement

This.

The emphasis being on single layer. You can find many papers talking about few layer graphene or bi/tri-layer graphene. So far as semantics are concerned that is not graphene. That is graphite. Very, very thin graphite. Only a single layer is graphene. The properties of a single layer compared to even a bi-layer are quite different from a nanophysics perspective.

However, many of the amazing properties graphene is lauded for are still present in few-layer “graphene”. So from a manufacturing point of view, often very, very thin graphite is just as good.

The fact is that most of the techniques we currently have for producing manufacturing scale graphene will result in sheets that have areas that are true graphene as well as areas that are really bi/tri layer. This has to do with the growth processes or the mass exfoliation processes and is being refined by experts to a point where they can make the very best end product possible. But it is still massively poorer quality* than the old reliable “Scotch Tape” method used in the discovery of graphene.

By and large, because they are not large, flakes of graphene produced using the Scotch Tape method (such as the ones I use) are used in labs to probe fundamental physics questions and discover how materials behave in 2D. While graphene grown in furnaces or spread out by chemicals are more focused on the application side. We are never going to get consistent flakes larger than a few tens of microns (the width of a human hair) with the Scotch Tape method. But some of the other methods are already boasting of printing sheets the size of newspapers.

Also, I have no idea if they held up a sheet at the Nobel Prizes. I can find no mention of this in the news. Graphene discoverers Novoselov and Geim did win a Nobel Prize in 2010. However, I think it is unlikely that they held up a sheet as graphene is all but transparent to visible light so it would not have made that much of an impact.

*Don’t let anyone tell you it’s not.

**In researching this I found a great resource, the history of graphene in links. Sorts out my weekend reading.

Lagoon

The colorful pattern represents a film of 7.5-nanometer lead sulfide nanocrystals evaporated on top of a silicon wafer. The islands are formed by micron-size “supercrystals”—faceted 3-D assemblies of the same nanocrystals. The picture is a true, unaltered image, obtained with an optical microscope in reflected light mode.

In order to invent new materials to use in better batteries, solar cells and other technological advances, scientists must delve deeply into the nanoscale—the nearly atomic scale where structures determine how materials react with each other. At the nanoscale, anything can happen; materials can change colors and form into astonishing structures.

Credit:  Paul Podsiadlo and Elena Shevchenko/ Argonne National Laboratory.

newscenter.lbl.gov
Strange New Twist: Berkeley Researchers Discover Möbius Symmetry in Metamaterials

Möbius symmetry, the topological phenomenon that yields a half-twisted strip with two surfaces but only one side, has been a source of fascination since its discovery in 1858 by German mathematician August Möbius. As artist M.C. Escher so vividly demonstrated in his “parade of ants,” it is possible to traverse the “inside” and “outside” surfaces of a Möbius strip without crossing over an edge. For years, scientists have been searching for an example of Möbius symmetry in natural materials without any success. Now a team of scientists has discovered Möbius symmetry in metamaterials – materials engineered from artificial “atoms” and “molecules” with electromagnetic properties that arise from their structure rather than their chemical composition.

nytimes.com
Scientists Report Finding Reliable Way to Teleport Data - NYTimes.com

Scientists in the Netherlands have moved a step closer to overriding one of Albert Einstein’s most famous objections to the implications of quantum mechanics, which he described as “spooky action at a distance.” In a paper published on Thursday in the journal Science, physicists at the Kavli Institute of Nanoscience at the Delft University of Technology reported that they were able to reliably teleport information between two quantum bits separated by three meters, or about 10 feet. Quantum teleportation is not the “Star Trek”-style movement of people or things; rather, it involves transferring so-called quantum information — in this case what is known as the spin state of an electron — from one place to another without moving the physical matter to which the information is attached. Classical bits, the basic units of information in computing, can have only one of two values — either 0 or 1. But quantum bits, or qubits, can simultaneously describe many values. They hold out both the possibility of a new generation of faster computing systems and the ability to create completely secure communication networks. Moreover, the scientists are now closer to definitively proving Einstein wrong in his early disbelief in the notion of entanglement, in which particles separated by light-years can still appear to remain connected, with the state of one particle instantaneously affecting the state of another. They report that they have achieved perfectly accurate teleportation of quantum information over short distances. They are now seeking to repeat their experiment over the distance of more than a kilometer. If they are able to repeatedly show that entanglement works at this distance, it will be a definitive demonstration of the entanglement phenomenon and quantum mechanical theory.

Studies done by Mark Lusk and colleagues at the Colorado School of Mines could significantly improve the efficiency of solar cells. Their work describes how the size of light-absorbing particles–quantum dots–affects the particles’ ability to transfer energy to electrons to generate electricity. The advance provides evidence to support a controversial idea, called multiple-exciton generation (MEG), which theorizes that it is possible for an electron that has absorbed light energy, called an exciton, to transfer that energy to more than one electron, resulting in more electricity from the same amount of absorbed light. Above is an image of multiple-exciton generation. Credit: Mark T. Lusk, Department of Physics, Colorado School of Mines

youtube

Magnetic Separation of Gold Nanoparticles

The video shows a cuvette (4mm in width) containing a mixture of gold and iron oxide nanoparticles with smart polymer coronas that are magnetically separated over the course of 20 minutes.

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These Penrose-style patterns are actually meticulously fabricated nanomagnets – each of those little white petals is less than 500 nanometers long. We posted a bit more about the technique and motivation behind playing with magnets on this tiny, tiny scale earlier today.

A physicist might see these images as the signatures of complex machinery, or perhaps as a pathway to next-gen electronics. Someone hungry might see pizzelle

A rose-like nanostructure holds the promise of increased capacity in next-generation energy storage.

Made out of germanium sulphide dust, this tiny crystalline bloom’s promise is due to its relatively enormous surface area packed into a tiny space. The material, Germanium sulphide, is also good at absorbing sunlight and converting it into usable power, making this little flower a potential solar cell.

Yes, science is beautiful.

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The self-assembly(1, 2)and the evolution(3)of a molecular nanowheel

Or, in other words, the creation of life-like cells from metal: Leroy Cronin and his team have try to demonstrate that life could be born also from metal atoms.

There is every possibility that there are life forms out there which aren’t based on carbon, On Mercury, the materials are all different. There might be a creature made of inorganic elements.
(Tadashi Sugawara, University of Tokyo)

(1) Haralampos N. Miras, Geoffrey J. T. Cooper, De-Liang Long, Hartmut Bögge, Achim Müller, Carsten Streb, Leroy Cronin (2010). Unveiling the Transient Template in the Self-Assembly of a Molecular Oxide Nanowheel Science, 327 (5961), 72-74 DOI: 10.1126/science.1181735
(2) Johannes Thiel, Pedro I. Molina, Mark D. Symes, Leroy Cronin (2012). Insights into the Self-Assembly Mechanism of the Modular Polyoxometalate “Keggin-Net” Family of Framework Materials and Their Electronic Properties Crystal growth and design, 12 (2), 902-908 DOI: 10.1021/cg201342z
(3) Haralampos N. Miras, Craig J. Richmond, De-Liang Long, Leroy Cronin (2012). Solution-Phase Monitoring of the Structural Evolution of a Molybdenum Blue Nanoring Jouornal of the American Chemical Society, 134 (852), 3816-3824 DOI: 10.1021/ja210206z

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Researchers at the University of California, Santa Barbara, led by composer JoAnn Kuchera-Morin, have created the AlloSphere, one of the largest immersive scientific instruments in the world. AlloSphere visitors experience what it is like to be inside an atom watching electrons spin, to fly through a person’s brain viewing tissue as landscape and hearing blood density levels as music, or to be a nanoparticle on the hunt for a cancerous tumor in a human vasculature system. What you see above:

  1. Mapping of fMRI data of the brain, revealing two layers of blood tissue flow with rectangular agents that are mining the blood density levels. Credit: Graham Wakefield, Lance Putnam, Wesley Smith, Dan Overholt, John Thompson, JoAnn Kuchera-Morin, and Marcos Novak
  2. An immersive surround view of a researcher flying through the vasculature system of the human body, as part of the “Center for Nanomedicine Project.” Credit: Pablo Colapinto, John Delaney, Haru Ji, Qian Liu, Gustavo Rincon, Graham Wakefield, Matthew Wright, JoAnn-Kuchera Morin, Jamey Marth
  3. As part of the Multimodal Representation of Quantum Mechanics: The Hydrogren Atom project, this image shows the hydrogen atom with spin, representing an orbital mixture of two probability waves. Credit: JoAnn-Kuchera Morin, Luca Peliti, Lance Putnam
  4. This image is from the Artificial Nature project, and displays a fluid dynamic environment containing bio-generative algorithms, representing plant and insect-like life forms. Credit: Haru Ji & Graham Wakefield Media Arts and Technology, UCSB

Nanoscience Tastes Wine

One sip of a perfectly poured glass of wine leads to an explosion of flavors in your mouth. Researchers at Aarhus Univ. have now developed a nanosensor that can mimic what happens in your mouth when you drink wine. The sensor measures how you experience the sensation of dryness in the beverage.

When wine growers turn their grapes into wine, they need to control a number of processes to bring out the desired flavor in the product that ends up in the wine bottle. An important part of the taste is known in wine terminology as astringency, and it is characteristic of the dry sensation you get in your mouth when you drink red wine in particular. It is the tannins in the wine that bring out the sensation that – otherwise beyond compare – can be likened to biting into an unripe banana. It is mixed with lots of tastes in the wine and feels both soft and dry.

Read more: http://www.laboratoryequipment.com/news/2014/09/nanoscience-tastes-wine