Tag Archives: Stanford University

Buckydiamondoids steer electron flow

One doesn’t usually think about buckyballs (Buckminsterfullerenes) and diamondoids as being together in one molecule but that has not stopped scientists from trying to join them and, in this case, successfully. From a Sept. 9, 2014 news item on ScienceDaily,

Scientists have married two unconventional forms of carbon — one shaped like a soccer ball, the other a tiny diamond — to make a molecule that conducts electricity in only one direction. This tiny electronic component, known as a rectifier, could play a key role in shrinking chip components down to the size of molecules to enable faster, more powerful devices.

Here’s an illustration the scientists have provided,

Illustration of a buckydiamondoid molecule under a scanning tunneling microscope (STM). In this study the STM made images of the buckydiamondoids and probed their electronic properties.

Illustration of a buckydiamondoid molecule under a scanning tunneling microscope (STM). In this study the STM made images of the buckydiamondoids and probed their electronic properties.

A Sept. 9, 2014 Stanford University news release by Glenda Chui (also on EurekAlert), which originated the news item, provides some information about this piece of international research along with background information on buckyballs and diamondoids (Note: Links have been removed),

“We wanted to see what new, emergent properties might come out when you put these two ingredients together to create a ‘buckydiamondoid,’” said Hari Manoharan of the Stanford Institute for Materials and Energy Sciences (SIMES) at the U.S. Department of Energy’s SLAC National Accelerator Laboratory. “What we got was basically a one-way valve for conducting electricity – clearly more than the sum of its parts.”

The research team, which included scientists from Stanford University, Belgium, Germany and Ukraine, reported its results Sept. 9 in Nature Communications.

Many electronic circuits have three basic components: a material that conducts electrons; rectifiers, which commonly take the form of diodes, to steer that flow in a single direction; and transistors to switch the flow on and off. Scientists combined two offbeat ingredients – buckyballs and diamondoids – to create the new diode-like component.

Buckyballs – short for buckminsterfullerenes – are hollow carbon spheres whose 1985 discovery earned three scientists a Nobel Prize in chemistry. Diamondoids are tiny linked cages of carbon joined, or bonded, as they are in diamonds, with hydrogen atoms linked to the surface, but weighing less than a billionth of a billionth of a carat. Both are subjects of a lot of research aimed at understanding their properties and finding ways to use them.

In 2007, a team led by researchers from SLAC and Stanford discovered that a single layer of diamondoids on a metal surface can emit and focus electrons into a tiny beam. Manoharan and his colleagues wondered: What would happen if they paired an electron-emitting diamondoid with another molecule that likes to grab electrons? Buckyballs are just that sort of electron-grabbing molecule.

Details are then provided about this specific piece of research (from the Stanford news release),

For this study, diamondoids were produced in the SLAC laboratory of SIMES researchers Jeremy Dahl and Robert Carlson, who are world experts in extracting the tiny diamonds from petroleum. The diamondoids were then shipped to Germany, where chemists at Justus-Liebig University figured out how to attach them to buckyballs.

The resulting buckydiamondoids, which are just a few nanometers long, were tested in SIMES laboratories at Stanford. A team led by graduate student Jason Randel and postdoctoral researcher Francis Niestemski used a scanning tunneling microscope to make images of the hybrid molecules and measure their electronic behavior. They discovered that the hybrid is an excellent rectifier: The electrical current flowing through the molecule was up to 50 times stronger in one direction, from electron-spitting diamondoid to electron-catching buckyball, than in the opposite direction. This is something neither component can do on its own.

While this is not the first molecular rectifier ever invented, it’s the first one made from just carbon and hydrogen, a simplicity researchers find appealing, said Manoharan, who is an associate professor of physics at Stanford. The next step, he said, is to see if transistors can be constructed from the same basic ingredients.

“Buckyballs are easy to make – they can be isolated from soot – and the type of diamondoid we used here, which consists of two tiny cages, can be purchased commercially,” he said. “And now that our colleagues in Germany have figured out how to bind them together, others can follow the recipe. So while our research was aimed at gaining fundamental insights about a novel hybrid molecule, it could lead to advances that help make molecular electronics a reality.”

Other research collaborators came from the Catholic University of Louvain in Belgium and Kiev Polytechnic Institute in Ukraine. The primary funding for the work came from U.S. the Department of Energy Office of Science (Basic Energy Sciences, Materials Sciences and Engineering Divisions).

Here’s a link to and a citation for the paper,

Unconventional molecule-resolved current rectification in diamondoid–fullerene hybrids by Jason C. Randel, Francis C. Niestemski,    Andrés R. Botello-Mendez, Warren Mar, Georges Ndabashimiye, Sorin Melinte, Jeremy E. P. Dahl, Robert M. K. Carlson, Ekaterina D. Butova, Andrey A. Fokin, Peter R. Schreiner, Jean-Christophe Charlier & Hari C. Manoharan. Nature Communications 5, Article number: 4877 doi:10.1038/ncomms5877 Published 09 September 2014

This paper is open access. The scientists provided not only a standard illustration but a pretty picture of the buckydiamondoid,

Caption: An international team led by researchers at SLAC National Accelerator Laboratory and Stanford University joined two offbeat carbon molecules -- diamondoids, the square cages at left, and buckyballs, the soccer-ball shapes at right -- to create "buckydiamondoids," center. These hybrid molecules function as rectifiers, conducting electrons in only one direction, and could help pave the way to molecular electronic devices. Credit: Manoharan Lab/Stanford University

Caption: An international team led by researchers at SLAC National Accelerator Laboratory and Stanford University joined two offbeat carbon molecules — diamondoids, the square cages at left, and buckyballs, the soccer-ball shapes at right — to create “buckydiamondoids,” center. These hybrid molecules function as rectifiers, conducting electrons in only one direction, and could help pave the way to molecular electronic devices.
Credit: Manoharan Lab/Stanford University

SWEET, sweet transporters

A Sept. 4, 2014 news item on Azonano is all about sugar,

Sugars are an essential source of energy for microrganisms, animals and humans. They are produced by plants, which convert energy from sunlight into chemical energy in the form of sugars through photosynthesis.

These sugars are taken up into cells, no matter whether these are bacteria, yeast, human cells or plant cells, by proteins that create sugar-specific pores in the membrane that surrounds a cell. These transport proteins are thus essential in all organisms. It is not surprising that the transporters of humans and plants are very similar since they evolved from their bacterial ancestors.

Sugar transporters can also be a source of vulnerability for plants and animals alike. In plants they can be susceptible to takeover by pathogens, hijacking the source of the plant’s food and energy. In animals, mutations in sugar transporters can lead to diseases, such as diabetes.

New work from a team led by the Stanford University School of Medicine’s Liang Feng and including Carnegie’s [Carnegie Institution for Science] Wolf Frommer has for the first time elucidated the atomic structures of the prototype of the sugar transporters (termed “SWEET” transporters) in plants and humans. These are bacterial sugar transporters, called SemiSWEETs (because they are just half the size of the human and plant ones). …

A Sept. 3, 2014 Carnegie Institution for Science news release, which originated the news item, describes the importance of understanding these transporters,

Until now, there was very limited information about the unique structures of these important transport proteins, which it turns out are different from all other known sugar transporters.

Discovering the structure of these proteins is important, as it is the key to unlocking the mechanism by which they work. And understanding their mechanism is crucial for figuring out what happens when these functions fail to work properly, because that knowledge can help in addressing the resulting diseases or growth problems in both plants and animals.

The research team performed a combination of structural and functional analyses of SemiSWEETs and SWEETs and was able to crystallize two examples in different states, demonstrating not only the protein’s structure, but much about its functionality as well.

They found that the SemiSWEETs do not act as a sugar channel, or tunnel, which allow sugars to pass across the membrane. Rather they act like an airlock, moving the sugars in multiple stages, two of which can be observed in the crystal structures. The SemiSWEETs, among the smallest known transport proteins, assemble in pairs, thereby creating a structure that looks like their bigger plant and human SWEET homologs. This marks the SWEET family of proteins as drastically different from other sugar transport proteins.

“One of the most-exciting parts of this discovery is the speed with which we were able to move from discovering these novel sugar transporters, to determining their actual structure, to showing how they work,” Frommer said. “Fantastic progress made possible by a collaboration with a structural biologist from Stanford University. Our findings highlight the potential practical applications of this information in improving crop yields as well as in addressing human diseases.”

Here’s a link to and a citation for the paper,

Structures of bacterial homologues of SWEET transporters in two distinct conformations by Yan Xu, Yuyong Tao, Lily S. Cheung, Chao Fan, Li-Qing Chen, Sophia Xu, Kay Perry, Wolf B. Frommer, & Liang Feng. Nature (2014) doi:10.1038/nature13670 Published online 03 September 2014

This paper is behind a paywall.

Hummingbirds and ‘nano’ spy cameras

Hummingbird-inspired spy cameras have come a long way since the research featured in this Aug. 12, 2011 posting which includes a video of a robot camera designed to look like a hummingbird and mimic some of its extraordinary flying abilities. These days (2014) the emphasis appears to be on mimicking the abilities to a finer degree if Margaret Munro’s July 29, 2014 article for Canada.com is to be believed,

Tiny, high-end military drones are catching up with one of nature’s great engineering masterpieces.

A side-by-side comparison has found a “remarkably similar” aerodynamic performance between hummingbirds and the Black Hornet, the most sophisticated nano spycam yet.

“(The) Average Joe hummingbird” is about on par with the tiny helicopter that is so small it can fit in a pocket, says engineering professor David Lentink, at Stanford University. He led a team from Canada [University of British Columbia], the U.S. and the Netherlands [Wageningen University and Eindhoven University of Technology] that compared the birds and the machine for a study released Tuesday [July 29, 2014].

For a visual comparison with the latest nano spycam (Black Hornet), here’s the ‘hummingbird’ featured in the 2011 posting,

The  Nano Hummingbird, a drone from AeroVironment designed for the US Pentagon, would fit into any or all of those categories.

And, here’s this 2013 image of a Black Hornet Nano Helicopter inspired by hummingbirds,

Black Hornet Nano Helicopter UAVView licenseview terms Richard Watt - Photo http://www.defenceimagery.mod.uk/fotoweb/fwbin/download.dll/45153802.jpgCourtesy: Wikipedia

Black Hornet Nano Helicopter UAVView licenseview terms
Richard Watt – Photo http://www.defenceimagery.mod.uk/fotoweb/fwbin/download.dll/45153802.jpg Courtesy: Wikipedia

A July 30, 2014 Stanford University news release by Bjorn Carey provides more details about this latest research into hummingbirds and their flying ways,

More than 42 million years of natural selection have turned hummingbirds into some of the world’s most energetically efficient flyers, particularly when it comes to hovering in place.

Humans, however, are gaining ground quickly. A new study led by David Lentink, an assistant professor of mechanical engineering at Stanford, reveals that the spinning blades of micro-helicopters are about as efficient at hovering as the average hummingbird.

The experiment involved spinning hummingbird wings – sourced from a pre-existing museum collection – of 12 different species on an apparatus designed to test the aerodynamics of helicopter blades. The researchers used cameras to visualize airflow around the wings, and sensitive load cells to measure the drag and the lift force they exerted, at different speeds and angles.

Lentink and his colleagues then replicated the experiment using the blades from a ProxDynamics Black Hornet autonomous microhelicopter. The Black Hornet is the most sophisticated microcopter available – the United Kingdom’s army uses it in Afghanistan – and is itself about the size of a hummingbird.

Even spinning like a helicopter, rather than flapping, the hummingbird wings excelled: If hummingbirds were able to spin their wings to hover, it would cost them roughly half as much energy as flapping. The microcopter’s wings kept pace with the middle-of-the-pack hummingbird wings, but the topflight wings – those of Anna’s hummingbird, a species common throughout the West Coast – were still about 27 percent more efficient than engineered blades.

Hummingbirds acing the test didn’t particularly surprise Lentink – previous studies had indicated hummingbirds were incredibly efficient – but he was impressed with the helicopter.

“The technology is at the level of an average Joe hummingbird,” Lentink said. “A helicopter is really the most efficient hovering device that we can build. The best hummingbirds are still better, but I think it’s amazing that we’re getting closer. It’s not easy to match their performance, but if we build better wings with better shapes, we might approximate hummingbirds.”

Based on the measurements of Anna’s hummingbirds, Lentink said there is potential to improve microcopter rotor power by up to 27 percent.

The high-fidelity experiment also provided an opportunity to refine previous rough estimates of muscle power. Lentink’s team learned that hummingbirds’ muscles produce a surprising 130 watts of energy per kilogram; the average for other birds, and across most vertebrates, is roughly 100 watts/kg.

Although the current study revealed several details of how a hummingbird hovers in one place, the birds still hold many secrets. For instance, Lentink said, we don’t know how hummingbirds maintain their flight in a strong gust, how they navigate through branches and other clutter, or how they change direction so quickly during aerial “dogfights.”

He also thinks great strides could be made by studying wing aspect ratios, the ratio of wing length to wing width. The aspect ratios of all the hummingbirds’ wings remarkably converged around 3.9. The aspect ratios of most wings used in aviation measure much higher; the Black Hornet’s aspect ratio was 4.7.

“I want to understand if aspect ratio is special, and whether the amount of variation has an effect on performance,” Lentink said. Understanding and replicating these abilities and characteristics could be a boon for robotics and will be the focus of future experiments.

“Those are the things we don’t know right now, and they could be incredibly useful. But I don’t mind it, actually,” Lentink said. “I think it’s nice that there are still a few things about hummingbirds that we don’t know.”

Agreed, it’s nice to know there are still a few mysteries left. You can watch the ‘mysterious’ hummingbird in this video courtesy of the Rivers Ingersoll Lentink Lab at Stanford University,

High speed video of Anna’s hummingbird at Stanford Arizona Cactus Garden.

Here’s a link to and a citation for the paper, H/T to Nancy Owano’s article on phys.org for alerting me to this story.

Hummingbird wing efficacy depends on aspect ratio and compares with helicopter rotors by Jan W. Kruyt, Elsa M. Quicazán-Rubio, GertJan F. van Heijst, Douglas L. Altshuler, and David Lentink.  J. R. Soc. Interface 6 October 2014 vol. 11 no. 99 20140585 doi: 10.1098/​rsif.2014.0585 Published [online] 30 July 2014

This is an open access paper.

Despite Munro’s reference to the Black Hornet as a ‘nano’ spycam, the ‘microhelicopter’ description in the news release places the device at the microscale (/1,000,000,000). Still, I don’t understand what makes it microscale since it’s visible to the naked eye. In any case, it is small.

US Air Force wants to merge classical and quantum physics

The US Air Force wants to merge classical and quantum physics for practical purposes according to a May 5, 2014 news item on Azonano,

The Air Force Office of Scientific Research has selected the Harvard School of Engineering and Applied Sciences (SEAS) to lead a multidisciplinary effort that will merge research in classical and quantum physics and accelerate the development of advanced optical technologies.

Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, will lead this Multidisciplinary University Research Initiative [MURI] with a world-class team of collaborators from Harvard, Columbia University, Purdue University, Stanford University, the University of Pennsylvania, Lund University, and the University of Southampton.

The grant is expected to advance physics and materials science in directions that could lead to very sophisticated lenses, communication technologies, quantum information devices, and imaging technologies.

“This is one of the world’s strongest possible teams,” said Capasso. “I am proud to lead this group of people, who are internationally renowned experts in their fields, and I believe we can really break new ground.”

A May 1, 2014 Harvard University School of Engineering and Applied Sciences news release, which originated the news item, provides a description of project focus: nanophotonics and metamaterials along with some details of Capasso’s work in these areas (Note: Links have been removed),

The premise of nanophotonics is that light can interact with matter in unusual ways when the material incorporates tiny metallic or dielectric features that are separated by a distance shorter than the wavelength of the light. Metamaterials are engineered materials that exploit these phenomena, producing strange effects, enabling light to bend unnaturally, twist into a vortex, or disappear entirely. Yet the fabrication of thick, or bulk, metamaterials—that manipulate light as it passes through the material—has proven very challenging.

Recent research by Capasso and others in the field has demonstrated that with the right device structure, the critical manipulations can actually be confined to the very surface of the material—what they have dubbed a “metasurface.” These metasurfaces can impart an instantaneous shift in the phase, amplitude, and polarization of light, effectively controlling optical properties on demand. Importantly, they can be created in the lab using fairly common fabrication techniques.

At Harvard, the research has produced devices like an extremely thin, flat lens, and a material that absorbs 99.75% of infrared light. But, so far, such devices have been built to order—brilliantly suited to a single task, but not tunable.

This project, however,is focused on the future (Note: Links have been removed),

“Can we make a rapidly configurable metasurface so that we can change it in real time and quickly? That’s really a visionary frontier,” said Capasso. “We want to go all the way from the fundamental physics to the material building blocks and then the actual devices, to arrive at some sort of system demonstration.”

The proposed research also goes further. A key thrust of the project involves combining nanophotonics with research in quantum photonics. By exploiting the quantum effects of luminescent atomic impurities in diamond, for example, physicists and engineers have shown that light can be captured, stored, manipulated, and emitted as a controlled stream of single photons. These types of devices are essential building blocks for the realization of secure quantum communication systems and quantum computers. By coupling these quantum systems with metasurfaces—creating so-called quantum metasurfaces—the team believes it is possible to achieve an unprecedented level of control over the emission of photons.

“Just 20 years ago, the notion that photons could be manipulated at the subwavelength scale was thought to be some exotic thing, far fetched and of very limited use,” said Capasso. “But basic research opens up new avenues. In hindsight we know that new discoveries tend to lead to other technology developments in unexpected ways.”

The research team includes experts in theoretical physics, metamaterials, nanophotonic circuitry, quantum devices, plasmonics, nanofabrication, and computational modeling. Co-principal investigator Marko Lončar is the Tiantsai Lin Professor of Electrical Engineering at Harvard SEAS. Co-PI Nanfang Yu, Ph.D. ’09, developed expertise in metasurfaces as a student in Capasso’s Harvard laboratory; he is now an assistant professor of applied physics at Columbia. Additional co-PIs include Alexandra Boltasseva and Vladimir Shalaev at Purdue, Mark Brongersma at Stanford, and Nader Engheta at the University of Pennsylvania. Lars Samuelson (Lund University) and Nikolay Zheludev (University of Southampton) will also participate.

The bulk of the funding will support talented graduate students at the lead institutions.

The project, titled “Active Metasurfaces for Advanced Wavefront Engineering and Waveguiding,” is among 24 planned MURI awards selected from 361 white papers and 88 detailed proposals evaluated by a panel of experts; each award is subject to successful negotiation. The anticipated amount of the Harvard-led grant is up to $6.5 million for three to five years.

For anyone who’s not familiar (that includes me, anyway) with MURI awards, there’s this from Wikipedia (Note: links have been removed),

Multidisciplinary University Research Initiative (MURI) is a basic research program sponsored by the US Department of Defense (DoD). Currently each MURI award is about $1.5 million a year for five years.

I gather that in addition to the Air Force, the Army and the Navy also award MURI funds.

1st code poetry slam at Stanford University

It’s code as in computer code and slam as in performance competition which when added to the word poetry takes most of us into uncharted territory. Here’s a video clip featuring the winning entry, Say 23 by Leslie Wu, competing in Stanford University’s (located in California) 1st code poetry slam,


If you listen closely (this clip does not have the best sound quality), you can hear the words to Psalm 23 (from the bible).

Thanks to this Dec. 29, 2013 news item on phys.org for bringing this code poetry slam to my attention (Note: Links have been removed),

Leslie Wu, a doctoral student in computer science at Stanford, took an appropriately high-tech approach to presenting her poem “Say 23″ at the first Stanford Code Poetry Slam.

Wu wore Google Glass as she typed 16 lines of computer code that were projected onto a screen while she simultaneously recited the code aloud. She then stopped speaking and ran the script, which prompted the computer program to read a stream of words from Psalm 23 out loud three times, each one in a different pre-recorded-computer voice.

Wu, whose multimedia presentation earned her first place, was one of eight finalists to present at the Code Poetry Slam. Organized by Melissa Kagen, a graduate student in German studies, and Kurt James Werner, a graduate student in computer-based music theory and acoustics, the event was designed to explore the creative aspects of computer programming.

The Dec. 27, 2013 Stanford University news release by Mariana Lage, which originated the news item, goes on to describe the concept. the competition, and the organizers’ aims,

With presentations that ranged from poems written in a computer language format to those that incorporated digital media, the slam demonstrated the entrants’ broad interpretation of the definition of “code poetry.”

Kagen and Werner developed the code poetry slam as a means of investigating the poetic potentials of computer-programming languages.

“Code poetry has been around a while, at least in programming circles, but the conjunction of oral presentation and performance sounded really interesting to us,” said Werner. Added Kagen, “What we are interested is in the poetic aspect of code used as language to program a computer.”

Sponsored by the Division of Literatures, Cultures, and Languages, the slam drew online submissions from Stanford and beyond.

High school students and professors, graduate students and undergraduates from engineering, computer science, music, language and literature incorporated programming concepts into poem-like forms. Some of the works were written entirely in executable code, such as Ruby and C++ languages, while others were presented in multimedia formats. The works of all eight finalists can be viewed on the Code Poetry Slam website.

Kagen, Werner and Wu agree that code poetry requires some knowledge of programming from the spectators.

“I feel it’s like trying to read a poem in a language with which you are not comfortable. You get the basics, but to really get into the intricacies you really need to know that language,” said Kagen, who studies the traversal of musical space in Wagner and Schoenberg.

Wu noted that when she was typing the code most people didn’t know what she was doing. “They were probably confused and curious. But when I executed the poem, the program interpreted the code and they could hear words,” she said, adding that her presentation “gave voice to the code.”

“The code itself had its own synthesized voice, and its own poetics of computer code and singsong spoken word,” Wu said.

One of the contenders showed a poem that was “misread” by the computer.

“There was a bug in his poem, but more interestingly, there was the notion of a correct interpretation which is somewhat unique to computer code. Compared to human language, code generally has few interpretations or, in most cases, just one,” Wu said.

So what exactly is code poetry? According to Kagen, “Code poetry can mean a lot of different things depending on whom you ask.

“It can be a piece of text that can be read as code and run as program, but also read as poetry. It can mean a human language poetry that has mathematical elements and codes in it, or even code that aims for elegant expression within severe constraints, like a haiku or a sonnet, or code that generates automatic poetry. Poems that are readable to humans and readable to computers perform a kind of cyborg double coding.”

Werner noted that “Wu’s poem incorporated a lot of different concepts, languages and tools. It had Ruby language, Japanese and English, was short, compact and elegant. It did a lot for a little code.” Werner served as one of the four judges along with Kagen; Caroline Egan, a doctoral student in comparative literature; and Mayank Sanganeria, a master’s student at the Center for Computer Research in Music and Acoustics (CCRMA).

Kagen and Werner got some expert advice on judging from Michael Widner, the academic technology specialist for the Division of Literatures, Cultures and Languages.

Widner, who reviewed all of the submissions, noted that the slam allowed scholars and the public to “probe the connections between the act of writing poetry and the act of writing code, which as anyone who has done both can tell you are oddly similar enterprises.”

A scholar who specializes in the study of both medieval and machine languages, Widner said that “when we realize that coding is a creative act, we not only value that part of the coder’s labor, but we also realize that the technologies in which we swim have assumptions and ideologies behind them that, perhaps, we should challenge.”

I first encountered code poetry in 2006 and I don’t think it was new at that time but this is the first time I’ve encountered a code poetry slam. For the curious, here’s more about code poetry from the Digital poetry essay in Wikipedia (Note: Links have been removed),

… There are many types of ‘digital poetry’ such as hypertext, kinetic poetry, computer generated animation, digital visual poetry, interactive poetry, code poetry, holographic poetry (holopoetry), experimental video poetry, and poetries that take advantage of the programmable nature of the computer to create works that are interactive, or use generative or combinatorial approach to create text (or one of its states), or involve sound poetry, or take advantage of things like listservs, blogs, and other forms of network communication to create communities of collaborative writing and publication (as in poetical wikis).

The Stanford organizers have been sufficiently delighted with the response to their 1st code poetry slam that they are organizing a 2nd slam (from the Code Poetry Slam 1.1. homepage),

Call for Works 1.1

Submissions for the second Slam are now open! Submit your code/poetry to the Stanford Code Poetry Slam, sponsored by the Department of Literatures, Cultures, and Languages! Submissions due February 12th, finalists invited to present their work at a poetry slam (place and time TBA). Cash prizes and free pizza!

Stanford University’s Division of Literatures, Cultures, and Languages (DLCL) sponsors a series of Code Poetry Slams. Code Poetry Slam 1.0 was held on November 20th, 2013, and Code Poetry Slam 1.1 will be held Winter quarter 2014.

According to Lage’s news release you don’t have to be associated with Stanford University to be a competitor but, given that you will be performing your poetry there, you will likely have to live in some proximity to the university.

Do you hear what I hear?

It’s coming up Christmas time and as my thoughts turn to the music, Stanford University (California, US) researchers are focused on hearing and touch (the two are related) according to a Dec. 4, 2013 news item on Nanowerk,

Much of what is known about sensory touch and hearing cells is based on indirect observation. Scientists know that these exceptionally tiny cells are sensitive to changes in force and pressure. But to truly understand how they function, scientists must be able to manipulate them directly. Now, Stanford scientists are developing a set of tools that are small enough to stimulate an individual nerve or group of nerves, but also fast and flexible enough to mimic a realistic range of forces.

The Dec. 3, 2013 Stanford Report article by Cynthia McKelvey, which originated the news item, provides more detail about hearing and the problem the researchers are attempting to solve,

Our ability to interpret sound is largely dependent on bundles of thousands of tiny hair cells that get their name from the hair-like projections on their top surfaces. As sound waves vibrate the bundles, they force proteins in the cells’ surfaces to open and allow electrically charged molecules, called ions, to flow into the cells. The ions stimulate each hair cell, allowing it to transfer information from the sound wave to the brain. Hair bundles are more sensitive to particular frequencies of sound, which allows us to tell the difference between a siren and a subwoofer.

People with damaged or congenital defects in these delicate hair cells suffer from severe, irreversible hearing loss. Scientists remain unsure how to treat this form of hearing loss   because they do not know how to repair or replace a damaged hair cell. Physical manipulation of the cells is key to exploring the fine details of how they function. This new probe is the first tool nimble enough to do it.

The article also goes on to describe the ‘nano’ probe,

The new force probe represents several advantages over traditional glass force probes. At 300 nanometers thick, Pruitt’s [Beth Pruitt, an associate professor of mechanical engineering] probe is just three-thousandths the width of a human hair. Made of flexible silicon, the probe can mimic a much wider range of sound wave frequencies than rigid glass probes, making it more practical for studying hearing. The probe also measures the force it exerts on hair cells as it pushes, a new achievement for high-speed force probes at such small sizes.

Manipulating the probe requires a gentle touch, said Pruitt’s collaborator, Anthony Ricci, a professor of otolaryngology at the Stanford School of Medicine. The tissue samples – in this case, hair cells from a rat’s ear – sit under a microscope on a stage floating on a cushion of air that keeps it isolated from vibrations.

The probe is controlled using three dials that function similarly to an Etch-a-Sketch. The first step of the experiment involves connecting a tiny, delicate glass electrode to the body of a single hair cell.

Using a similar manipulator, Ricci and his team then press the force probe on a single hair cell, and the glass electrode records the changes in the cell’s electrical output. Pruitt and Ricci say that understanding how physical changes prompt electrical responses in hair cells can lead to a better understanding of how people lose their hearing following damage to the hair cells.

The force probe has the potential to catalyze future research on sensory science, Ricci said.

Up to now, limits in technology have held scientists back from understanding important functions such as hearing, touch, and balance. Like hair cells in the ear, cells involved in touch and balance react to the flexing and stretching of their cell membranes. The force probe can be used to study those cells in the same manner that Pruitt and Ricci are using it to study hair cells.

Understanding the mechanics of how cells register these sensory inputs could lead to innovative new treatments and prosthetics. For example, Pruitt and Ricci think their research could help bioengineers build a better hair cell for people with impaired hearing from damage to their natural hair cells.

Stanford has produced a video about this work,

I find it fascinating that hearing and touch are related although I haven’t yet seen anything that describes or explains the relationship. As for anyone hoping for a Christmas carol, I think I’m going to hold off until later in the season.

Carbon nanotubes a second way: Cedric, the carbon nanotube computer

On the heels of yesterday’s(Sept. 26, 2013) posting about carbon nnanotubes as flexible gas sensors, I have this item about a computer fashioned from carbon nanotubes.

This wafer contains tiny computers using carbon nanotubes, a material that could lead to smaller, more energy-efficient processors. Courtesy Standford University

This wafer contains tiny computers using carbon nanotubes, a material that could lead to smaller, more energy-efficient processors. Courtesy Stanford University

To me this looks more like a ping pong bat than a computer wafer. Regardless, here’s more about it from a Sept. 25, 2013 news item by James Morgan for BBC (British Broadcasting Corporation) News online,

The first computer built entirely with carbon nanotubes has been unveiled, opening the door to a new generation of digital devices.

“Cedric” is only a basic prototype but could be developed into a machine which is smaller, faster and more efficient than today’s silicon models.

Nanotubes have long been touted as the heir to silicon’s throne, but building a working computer has proven awkward.

Cedric is the most complex carbon-based electronic system yet realised.

So is it fast? Not at all. It might have been in 1955.
The computer operates on just one bit of information, and can only count to 32.

“In human terms, Cedric can count on his hands and sort the alphabet. But he is, in the full sense of the word, a computer,” says co-author [of the paper published in Nature] Max Shulaker.

Tom Abate’s Sept. 26, 2013 article for Stanford Report provides more detail about carbon nanotubes, their potential for replacing silicon chips and associated problems,

“Carbon nanotubes [CNTs] have long been considered as a potential successor to the silicon transistor,” said Professor Jan Rabaey, a world expert on electronic circuits and systems at the University of California-Berkeley.

Why worry about a successor to silicon?

Such concerns arise from the demands that designers place upon semiconductors and their fundamental workhorse unit, those on-off switches known as transistors.

For decades, progress in electronics has meant shrinking the size of each transistor to pack more transistors on a chip. But as transistors become tinier, they waste more power and generate more heat – all in a smaller and smaller space, as evidenced by the warmth emanating from the bottom of a laptop.

Many researchers believe that this power-wasting phenomenon could spell the end of Moore’s Law, named for Intel Corp. co-founder Gordon Moore, who predicted in 1965 that the density of transistors would double roughly every two years, leading to smaller, faster and, as it turned out, cheaper electronics.

But smaller, faster and cheaper has also meant smaller, faster and hotter.

“CNTs could take us at least an order of magnitude in performance beyond where you can project silicon could take us,” Wong [another co-author of the paper]  said.

But inherent imperfections have stood in the way of putting this promising material to practical use.

First, CNTs do not necessarily grow in neat parallel lines, as chipmakers would like.

Over time, researchers have devised tricks to grow 99.5 percent of CNTs in straight lines. But with billions of nanotubes on a chip, even a tiny degree of misaligned tubes could cause errors, so that problem remained.

A second type of imperfection has also stymied CNT technology.

Depending on how the CNTs grow, a fraction of these carbon nanotubes can end up behaving like metallic wires that always conduct electricity, instead of acting like semiconductors that can be switched off.

Since mass production is the eventual goal, researchers had to find ways to deal with misaligned and/or metallic CNTs without having to hunt for them like needles in a haystack.

“We needed a way to design circuits without having to look for imperfections or even know where they were,” Mitra said.

The researchers have dubbed their solution an “imperfection-immune design,” from the Abate article,

To eliminate the wire-like or metallic nanotubes, the Stanford team switched off all the good CNTs. Then they pumped the semiconductor circuit full of electricity. All of that electricity concentrated in the metallic nanotubes, which grew so hot that they burned up and literally vaporized into tiny puffs of carbon dioxide. This sophisticated technique eliminated the metallic CNTs in the circuit.

Bypassing the misaligned nanotubes required even greater subtlety.

The Stanford researchers created a powerful algorithm that maps out a circuit layout that is guaranteed to work no matter whether or where CNTs might be askew.

“This ‘imperfections-immune design’ [technique] makes this discovery truly exemplary,” said Sankar Basu, a program director at the National Science Foundation.

The Stanford team used this imperfection-immune design to assemble a basic computer with 178 transistors, a limit imposed by the fact that they used the university’s chip-making facilities rather than an industrial fabrication process.

Their CNT computer performed tasks such as counting and number sorting. It runs a basic operating system that allows it to swap between these processes. In a demonstration of its potential, the researchers also showed that the CNT computer could run MIPS, a commercial instruction set developed in the early 1980s by then Stanford engineering professor and now university President John Hennessy.

Though it could take years to mature, the Stanford approach points toward the possibility of industrial-scale production of carbon nanotube semiconductors, according to Naresh Shanbhag, a professor at the University of Illinois at Urbana-Champaign and director of SONIC, a consortium of next-generation chip design research.

Here’s a link to and a citation for the paper,

Carbon nanotube computer by Max M. Shulaker, Gage Hills, Nishant Patil, Hai Wei, Hong-Yu Chen, H.-S. Philip Wong, & Subhasish Mitra. Nature 501, 526–530 (26 September 2013) doi:10.1038/nature12502

This article is behind a paywall but you can gain temporary access via ReadCube.

Keeping it together—new glue for lithium-ion batteries

Glue isn’t the first component that comes to my mind when discussing ways to make lithium-ion (Li-ion) batteries more efficient but researchers at SLAC National Accelerator Laboratory at Stanford University have proved that the glue used to bind a Li-ion battery together can make a difference to its efficiency (from the Aug. 20, 2013 news item on phys.org),

When it comes to improving the performance of lithium-ion batteries, no part should be overlooked – not even the glue that binds materials together in the cathode, researchers at SLAC and Stanford have found.

Tweaking that material, which binds lithium sulfide and carbon particles together, created a cathode that lasted five times longer than earlier designs, according to a report published last month in Chemical Science. The research results are some of the earliest supported by the Department of Energy’s Joint Center for Energy Storage Research.

“We were very impressed with how important this binder was in improving the lifetime of our experimental battery,” said Yi Cui, an associate professor at SLAC and Stanford who led the research.

The Aug. 19, 2013 SLAC news release by Mike Ross, which originated the news item, provides context for this accidental finding about glue and Li-ion batteries,

Researchers worldwide have been racing to improve lithium-ion batteries, which are one of the most promising technologies for powering increasingly popular devices such as mobile electronics and electric vehicles. In theory, using silicon and sulfur as the active elements in the batteries’ terminals, called the anode and cathode, could allow lithium-ion batteries to store up to five times more energy than today’s best versions. But finding specific forms and formulations of silicon and sulfur that will last for several thousand charge-discharge cycles during real-life use has been difficult.

Cui’s group was exploring how to create a better cathode by using lithium sulfide rather than sulfur. The lithium atoms it contains can provide the ions that shuttle between anode and cathode during the battery’s charge/discharge cycle; this in turn means the battery’s other electrode can be made from a non-lithium material, such as silicon. Unfortunately, lithium sulfide is also electrically insulating, which greatly reduces any battery’s performance. To overcome this, electrically conducting carbon particles can be mixed with the sulfide; a glue-like material – the binder – holds it all together.

Scientists in Cui’s [Yi Cui, an associate professor at SLAC and Stanford who led the research] group devised a new binder that is particularly well-suited for use with a lithium sulfide cathode ­– and that also binds strongly with intermediate polysulfide molecules that dissolve out of the cathode and diminish the battery’s storage capacity and useful lifetime.

The experimental battery using the new binder, known by the initials PVP, retained 94 percent of its original energy-storage capacity after 100 charge/discharge cycles, compared with 72 percent for cells using a conventionally-used binder, known as PVDF. After 500 cycles, the PVP battery still had 69 percent of its initial capacity.

Cui said the improvement was due to PVP’s much stronger affinity for lithium sulfide; together they formed a fine-grained lithium sulfide/carbon composite that made it easier for lithium ions to penetrate and reach all of the active material within the cathode. In contrast, the previous binder, PVDF, caused the composite to grow into large clumps, which hindered the lithium ions’ penetration and ruined the battery within 100 cycles

Even the best batteries lose some energy-storage capacity with each charge/discharge cycle. Researchers aim to reduce such losses as much as possible. Further enhancements to the PVP/lithium sulfide cathode combination will be needed to extend its lifetime to more than 1,000 cycles, but Cui said he finds it encouraging that improving the usually overlooked binder material produced such dramatic benefits.

Here’s a link to and a citation for the published paper,

Stable cycling of lithium sulfide cathodes through strong affinity with a bifunctional binder by Zhi Wei Seh, Qianfan Zhang, Weiyang Li, Guangyuan Zheng, Hongbin Yaoa, and Yi Cui. Chem. Sci., 2013,4, 3673-3677 DOI: 10.1039/C3SC51476E First published online 11 Jul 2013

There’s a note on the website stating the article is free but the instructions for accessing the article are confusing seeming to suggest you need a subscription of some sort or you need to register for the site.

I have written about Yi Cui’s work with lithium-ion batteries before including this Jan. 9, 2013 posting, How is an eggshell like a lithium-ion battery?, which also features a news release by Mike Ross.

Teachers play with crayons while learning about nanotechnology at Stanford University

Stanford University’s Center for Probing the Nanoscale runs a program for middle school science teachers where they, over a period of a week, participate in lectures and more (from the Center’s Summer Institute for Middle School Teachers webpage),

Daily sessions focus on content lectures and inquiry-based modules that explicitly address California’s 5-8th grade physical science content standards. Teachers will also receive a hands-on activity kit with many fun activities that bring nanoscience into the classroom.

  • learn about nanoscience and nanotechnology in simple terms
  • develop and receive hands-on activities targeting CA 5-8th grade science content standards
  • interact with scientists at Stanford University
  • tour research labs and see instruments in action
  • receive a $850 stipend and professional development units ($550 after completion of SIMST, $300 after implementing a nano lesson in the classroom)

An Aug. 1, 2013 news item on Azonano provides a description of a “fun activity,”

After a lecture on nanofabrication, Maria Wang, associate director at Stanford’s Center for Probing the Nanoscale, handed out white paper, boxes of colored crayons, thick black crayons and pipette tips. …

Following Wang’s directions, the 13 teachers quickly got to work. Each filled a small square of paper with color, covered the color entirely with several layers of black crayon, then etched a design into the paper by pressing the pipette tip through the black layers to expose a colorful pattern – mimicking the plasma etching they had learned about in the lecture.

“These pipette tips are kind of high tech for this activity, but I think it’s neat to find any opportunity to introduce tools that we use in the lab to you,” Wang told the teachers, who were sitting at small tables in a classroom in the McCullough Building. “You can actually just use a paper clip as a low-cost solution in case you don’t have access to pipette tips.”

Michael Wilson, who teaches sixth-, seventh- and eighth-grade science at Stewart Elementary School in Pinole, Calif., said crayon etching, which is taught in art classes at his school, offered the possibility of injecting a “little science” into an art lesson.

“Now we can say this is why that happens,” said Wilson.

The crayon etching exercise, a demonstration of “top-down fabrication,” was one of a dozen hands-on activities scheduled during the July 22-26 [2013] summer institute.

The July 31, 2013 Stanford Report article by Kathleen J. Sullivan, which originated the news item, explains this program’s raison d’être,

David Goldhaber-Gordon, director of the center [Center for Probing the Nanoscale], said most elementary school students are excited about science, but lose interest or confidence in their ability to do science during the middle school years.

“Middle school science teachers are hungry for both subject area knowledge and for reinvigorating their passion for science,” said Goldhaber-Gordon, a Stanford associate professor of physics. “We select teacher participants primarily from schools with students who are traditionally underrepresented in science. In this way, we hope to impact the lives and decisions of thousands of students each year. More than ever today, as our economy is driven by scientific and technological developments, we need a scientifically literate populace. Middle school is a key time to reach students.”

Interestingly (to me), the center is a joint Stanford University/IBM Corporation project.