Science
The world’s fastest oscillating nanomachine
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It’s an antenna, it’s a nanomachine, and it’s a macroscopic quantum system. This antenna, made of 50 billion atoms, is so far the largest structure to display quantum mechanical movements. It’s also the fastest device of its kind in the world, oscillating about 1.5 billion times per second. Such technology might soon be used in our cell phones. But more importantly, this nanomechanical device bridges classic and quantum physics. Such ”mechanical/quantum mechanical hybrids could be used for quantum computing” in the future. Read more…
Here is the introduction from this Boston University news release.
A team of Boston University physicists led by Assistant Professor Pritiraj Mohanty developed the nanomechanical oscillator. Operating at gigahertz speeds, the technology could help further miniaturize wireless communication devices like cell phones, which exchange information at gigahertz frequencies. But, more important to the researchers, the oscillator lies at the cusp of classic physics, what people experience everyday, and quantum physics, the behavior of the molecular world.
Please note that this is the second appearance of Mohanty’s team in this space. I already mentioned their works back in October 2004 in “Nanomechanical Memory Outstrips Chip Technology.”
Now, let’s look at some — impressive — numbers.
Comprised of 50 billion atoms, the antenna built by Mohanty’s team is so far the largest structure to display quantum mechanical movements.
“It’s a truly macroscopic quantum system,” says Alexei Gaidarzhy, a graduate student in the BU College of Engineering’s Department of Aerospace and Mechanical Engineering. The device is also the fastest of its kind, oscillating at 1.49 gigahertz, or 1.49 billion times a second, breaking the previous record of 1.02 gigahertz achieved by a nanomachine produced by another group.
The above image shows different views of this nanomechanical structure. The center, (a), is a scanning electron micrograph of the suspended antenna oscillator. The nanomechanical antenna consists of a central silicon beam, 10.7 microns long and 400 nm wide, that bears a “paddle” array 500 nm long and 200 nm wide along each side. In (b), you can see a modal simulation of the antenna structure, showing the low frequency fundamental resonance mode. And in the high order collective mode (c), the paddles vibrate at their own natural frequency. (Credit: Pritiraj Mohanty, Boston University)
The research work has been published in a recent issue of Physical Review Letters on January 25, 2005 under the name “Evidence for Quantized Displacement in Macroscopic Nanomechanical Oscillators.” Here is a link to the abstract.
We report the observation of discrete displacement of nanomechanical oscillators with gigahertz-range resonance frequencies at millikelvin temperatures. The oscillators are nanomachined single-crystal structures of silicon, designed to provide two distinct sets of coupled elements with very low and very high frequencies. With this novel design, femtometer-level displacement of the frequency-determining element is amplified into collective motion of the entire micron-sized structure. The observed discrete response possibly results from energy quantization at the onset of the quantum regime in these macroscopic nanomechanical oscillators.
And here is a link to the full article (PDF format, 4 pages, 955 KB). The above illustration comes from this article.
Finally, for explanations written in — almost — plain English, you might read the news release quoted above.
Sources: Boston University, via EurekAlert!, February 9, 2005; and various websites
Related stories can be found in the following categories.
- Nanotechnology
- Physics
- Quantum World
- Science
Spotting Evolution on the Wing
What is responsible for the evolution of forms and shapes of living organisms? Is this our genes or the DNA mechanisms which control where genes are used in the making of the animal’s body? Scientists from the University of Wisconsin-Madison have found the answer by studying the various spots on the wings of a common fruit fly. In this article, they explain that molecular switches control where the pigmentation is deployed. Common genes are controlled to produce an endless array of patterns, decoration and body architecture found in animals. And it is almost certain that these molecular switches are at work in other animals, including humans. What is even more fascinating is how it works. According to the researchers, evolution is a combination of chance and ecological necessity, which selects those things that are going to be kept. It means that animals’ features are just accidents, but accidents that are preserved because they confer some kind of advantage. Read more…
By analyzing the genetic origin of a modest spot on a fruit fly wing, Howard Hughes Medical Institute (HHMI) researchers have discovered a molecular mechanism that explains, in part, how new patterns can evolve. The secret appears to be specific segments of DNA that orchestrate where proteins are used in the construction of an insect’s body.
The researchers chose to study the evolution of the wing spot on the fruit fly because it is a simple trait with a well-understood evolutionary history. While ancient fruit fly species lack the spots, said HHMI investigator Sean B. Carroll, some species that evolved later have developed them under the pressure of sexual selection. The wing spots offer a survival advantage to males, who depend on the decorations to “impress” females to choose them in the mating process.
| Like butterflies, different species of fruit flies decorate their wings with a great diversity of spots and patterns. Digging deep into a single gene that produce pigmentation in the flies, a group led by UW-Madison biologist Sean Carroll has found the molecular switches that control where the pigmentation is deployed. The finding explains how common genes can be controlled to produce the seemingly endless array of patterns, decoration and body architecture found in animals. (Credit for photo and caption: Nicolas Gompel and Benjamin Prud’homme, University of Wisconsin-Madison) |
You’ll find other pictures on this page which also contains a link to a short movie where you can see “the male fruit fly showing off his wing spots in an effort to get the attention of the ladies.” (QuickTime format, 35 seconds, 10.1 MB).
The research work has been published by Nature on February 3, 2005 under the name “Chance caught on the wing: cis-regulatory evolution and the origin of pigment patterns in Drosophila” (Vol. 433, No. 7025, Pages 481 - 487). Here is a link to the abstract.
The gain, loss or modification of morphological traits is generally associated with changes in gene regulation during development. However, the molecular bases underlying these evolutionary changes have remained elusive. Here we identify one of the molecular mechanisms that contributes to the evolutionary gain of a male-specific wing pigmentation spot in Drosophila biarmipes, a species closely related to Drosophila melanogaster. We show that the evolution of this spot involved modifications of an ancestral cis-regulatory element of the yellow pigmentation gene. This element has gained multiple binding sites for transcription factors that are deeply conserved components of the regulatory landscape controlling wing development, including the selector protein Engrailed. The evolutionary stability of components of regulatory landscapes, which can be co-opted by chance mutations in cis-regulatory elements, might explain the repeated evolution of similar morphological patterns, such as wing pigmentation patterns in flies.
Here are few more resources if you’re interested by this findings.
- Sean Carroll’s lab
- Scientists find portal to how animals evolve
An article from the University of Wisconsin-Madison
- A news release from the University of Wisconsin-Madison
Sources: Howard Hughes Medical Institute, February 4, 2005, and various websites
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- DNA
- Genetics
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Transparent Transistors Are Coming
Transparent electronics is an emerging technology which aims to produce invisible electronic circuits. Now, researchers from Oregon report they made a major advance in transparent electronics. Their zinc-tin-oxide ‘thin-film’ materials are amorphous, physically robust, chemically stable and cheap to produce at just above room temperature. These new materials and transistors offer many new possibilities for consumer electronics, transportation, business and the military. Even if these transparent transistors don’t show up inside your next computer, they might soon appear in flat panel screens, flexible electronics devices you’ll carry with you, and even in your car windshields. But it should take some time. Read more…
Before going further, please remember that the following quotes are written in PR jargon. So read them with a grain of salt…
Researchers at Oregon State University (OSU) and Hewlett Packard have reported their first example of an entirely new class of materials which could be used to make transparent transistors that are inexpensive, stable, and environmentally benign. This could lead to new industries and a broad range of new consumer products, scientists say.
This is a significant breakthrough in the emerging field of transparent electronics, experts say. The new transistors are not only transparent, but they work extremely well and could have other advantages that will help them transcend carbon-based transistor materials, such as organics and polymers, that have been the focus of hundreds of millions of dollars of research around the world.
It’s time for more ‘technical’ details about these zinc-tin-oxide thin film transistors.
They are amorphous, meaning they have no long range crystalline order, which helps to keep processing costs a great deal lower. They are also physically robust — hard to scratch, chemically stable, resist etching, and have a very smooth surface. They are made from low cost, readily-available elements such as zinc and tin, which raise no environmental concerns.
“What has been most surprising, however, is that we can make high quality oxide transistors with these new materials at just above room temperature,” said John Wager, a professor of electrical and computer engineering at OSU. “Simply put, that’s shocking. Most integrated circuits made today, by comparison, are produced at temperatures between 700-1,100 degrees centigrade.”
| Here is a photograph of a 1 inch by 1 inch glass substrate patterned with spin-coated zinc oxide transparent transistors, sitting on the top of a dollar bill. There are 56 transparent transistors present in the red box. Can you see them? Of course not, they’re transparent. (Credit: Oregon State University) |
As you probably guessed by now, this technology is a nascent one. But researchers are very optimistic about future uses, for example with gas sensor systems.
These sensors are used extensively in automotive and other mechanical applications, and the new zinc-tin oxide transistors might allow the creation of a new type of gas sensor whose sensitivity is electronically controlled over a wide dynamic range.
In the field of transparent applications, there should be uses in consumer electronics, transportation, business and the military. Automobile windshields could transmit visual information. Glass in almost any setting could also double as an electronic device, possibly improving security systems or transparent displays. The military is extremely interested in research of this type because of possible uses in sophisticated technology or fighting equipment.
For more information about transparent electronics, you should visit John Wager’s home page at Oregon State’s School of Electrical Engineering and Computer Science. Here is a direct link to his research activities.
The latest work done by Wager and his colleagues has been published online by Applied Physics Letters on December 23, 2004. Here is a link to the abstract of this paper named “High mobility transparent thin-film transistors with amorphous zinc tin oxide channel layer.”
A previous paper about these see-through transistors was published last year by the Journal of Physics D: Applied Physics. Here is a link to this full paper, named “Spin-coated zinc oxide transparent transistors,” from which the above illustration was extracted.
Sources: Oregon State University news release, via EurekAlert!, December 28, 2004; Applied Physics Letters, Volume 86, Issue 1, January 3, 2005; Journal of Physics D: Applied Physics, Volume 36, Number 20, October 21, 2003; and various websites
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- Electronics
- Future
- Materials
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Water Helps to Clean Carbon Nanotubes
Carbon nanotubes, which can have useful electrical or optical properties, are typically grown using chemical vapor deposition techniques. During this process, amorphous and useless carbon layers are also produced, meaning that a post-growth purification process is needed. Not anymore. According to this article from Technology Research News (TRN), Japanese researchers have successfully used water to get rid of these impurities. The idea of using water to clean carbon nanotubes is so simple that I’m amazed that nobody thought about it before. Anyway, this method, which eliminates the post-growth purification process, still needs some improvements and will not help to mass produce carbon nanotubes before at least five years. There were several other announcements about nanotechnology achievements in the last two weeks, so read more…
Here are the opening paragraphs of the TRN article.
Washing away impurities with water turns out to be as good for growing carbon nanotubes as it is for keeping a clean house.
Carbon nanotubes show great promise as building blocks for molecular machines, high-speed electronics and super-strong materials, but it has proven difficult to reliably grow large amounts of pure carbon nanotubes and to keep the growth process orderly.
And here are the essential details of this new cleaning process.
Researchers from the Japanese National Institute of Advanced Industrial Science and Technology (AIST) have added water to the standard method of manufacturing carbon nanotubes to produce tall, dense, vertically-aligned stands of pure nanotubes.
The purity of the nanotubes makes the usual post-growth purification process unnecessary. This makes the method quicker, less expensive and less likely to damage the nanotubes than existing processes, said Kenji Hata, a senior researcher at the Japan National Institute of Advanced Industrial Science and Technology. Nanotubes produced using the method are orderly and pure enough for use in many fields, including biology, medical implants, chemistry, electronics and magnetics research, he said.
Please read the full article TRN article for other details and keep in mind that this method for growing carbon nanotubes is still a work in progress.
The method could be used to mass produce carbon nanotubes within five years, and for practical applications within ten years, said Hata.
| Here is a photo of a complex nanostructue obtained with this process and evocating a flower (Credit: AIST). |
The research work has been published by Science on November 19, 2004 under the name “Water-Assisted Highly Efficient Synthesis of Impurity-Free Single-Walled Carbon Nanotubes.” Here is a link to the abstract.
We demonstrate the efficient chemical vapor deposition synthesis of single-walled carbon nanotubes where the activity and lifetime of the catalysts are enhanced by water. Water-stimulated enhanced catalytic activity results in massive growth of superdense and vertically aligned nanotube forests with heights up to 2.5 millimeters that can be easily separated from the catalysts, providing nanotube material with carbon purity above 99.98%. Moreover, patterned, highly organized intrinsic nanotube structures were successfully fabricated. The water-assisted synthesis method addresses many critical problems that currently plague carbon nanotube synthesis.
This column is getting too long, so you’ll find other references in this sidebar, “Nanotech News Roundup #1.” Maybe there will be another edition in about a couple of weeks.
Sources: Eric Smalley, Technology Research News, December 1-8, 2004; Science, November 19, 2004
Related stories can be found in the following categories.
- Materials
- Nanotechnology
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World’s Strongest and Kindest Acid Discovered
Researchers at the University of California, Riverside (UCR), have discovered the world’s strongest acid, according to Nature. It’s a million times stronger than concentrated sulfuric acid and about a billion times stronger than the acids found in your stomach. But surprisingly, it’s also one of the least corrosive. So you might soon find one of these new carborane acids, or superacids, in vitamins bought at your local drugstore. Even if this is not appealing to you, these researchers have other projects. They want to have fun by building molecules that have never been made before. Read more…
This new superacid is even better described in this UCR news release. Let’s start with the introduction.
Researchers at the University of California, Riverside have discovered the world’s strongest acid. Remarkably it is also the gentlest acid. This non-toxic and non-corrosive acid may have a role in processes such as improving the quality of gasoline, developing polymers and synthesizing pharmaceuticals.
The most important characteristic of these carborane acids is that they have anextraordinary chemical stability.
They have an icosahedral arrangement of eleven boron atoms plus one carbon atom, which is probably the most chemically stable cluster of atoms in all of chemistry, according to Christopher Reed, UC Riverside Distinguished Professor of Chemistry. This means that the carborane part of the acid cannot participate in the chemistry of corrosion and decomposition that fluoride and nitrate show in hydrofluoric acid and nitric acid.
| Here is a diagram of the CHB11R5X6 carborane ions (Credit: UCR). | |
| And here is another diagram showing the structure of the carborane, part of the world’s strongest acid. [Atom color code: orange = boron, gray = carbon, green = chlorine, white = hydrogen.] (Credit: UCR). |
Now, how strong are these superacids?
The strongest one is at least a million times stronger than concentrated sulfuric acid (H2SO4) and hundreds of times stronger than the previous record holder, fluorosulfuric acid (HFSO3). Concentrated sulfuric acid is already more than a billion times (1012) stronger than dilute swimming pool acid or the acid in one’s stomach.
Fine, but how can we use these enormously strong acids? They could be used for example in hydrocarbon cracking, a process which raises the octane levels of gasoline.This could be useful, but Nature points to other possible usages.
They allow the production of ‘acidified’ organic molecules. These are compounds that have had a hydrogen ion added to them, as in the case of many vitamins in over-the-counter supplements.
Acidified compounds occur fleetingly in the digestion of food, petroleum refinement and drug manufacture, says Reed. Carborane acids could be used to study these elusive chemicals more closely, or even help chemical industries to run their reactions more efficiently.
But even more importantly, these researchers want more to have fun than to make money.
But the researchers’ immediate goal would be less of a money-spinner. They want to use carborane acids to acidify atoms of the inert gas xenon, simply because, they say, “it’s never been done before”.
And in the UCR news release, Reed adds the following.
Our research is driven by making molecules that have never been made before. Carborane acids are allowing us to do this. That is the true value of this research. Science gets advanced, and at the same time, students are experiencing the thrill of discovery as they become scientists.
I don’t know for you, but the idea of taking vitamins containing such strong acids disturbs me a little.
Anyway, if you want more information before taking your next dietary supplement, the research paper has been published by Angewandte Chemie under the ramarkably simple titlee “The Strongest Isolable Acid.” Here are the links to the abstract and to the full paper (PDF format, 4 pages). The diagram of the carborane ions was extracted from this paper.
Sources: Michael Hopkin, Nature, November 16, 2004; University of California, Riverside news release, November 15, 2004; Angewandte Chemie International Edition, Volume 43, Issue 40 , Pages 5352 - 5355, October 5, 2004
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- Chemistry
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