nanopolitan 2.0 » Science

Some materials links

Abi — Mon, 25 Dec 2006 18:09:37 +0000

To create their thin-film transistors, [Tobin J. ] Marks’ group [at Northwestern] combined films of the inorganic semiconductor indium oxide with a multilayer of self-assembling organic molecules that provides superior insulating properties.

Synthetic Gecko materials that mimics “microscopic hairs on a gecko foot”. It is “made of layers covered with thousands of stalks with splayed tips made of a polyimide, a synthetic like Nylon.”

Metamaterials with negative refractive index:

[Gunnar] Dolling’s metamaterial is made by depositing a layer of silver on a glass sheet, covering this with a thin layer of nonconducting magnesium fluoride, followed by another silver layer, forming a sandwich 100 nm thick. Dolling then etched an array of square holes through the sandwich to create a grid, similar to a wire mesh.

A key advance in Flexible electronics:

The trick to being able to manufacture—rather than handcraft—large arrays of single-crystal transistors was to devise a method for printing patterns of transistors on surfaces such as silicon wafers and flexible plastic. The first step is to put electrodes on these surfaces wherever a transistor is desired. Then the researchers make a stamp with the desired pattern out of a polymer called polydimethylsiloxane. After coating the stamp with a crystal growth agent called octadecyltriethoxysilane (OTS) and pressing it onto the surface, the researchers can then introduce a vapor of the organic crystal material onto the OTS-patterned surfaces. The vapor will condense and grow semiconducting organic single crystals only where the agent lies. With the crystals bridging the electrodes, transistors are formed.

Finally, is open peer review experiment at Nature a failure?

Nano-knives and superplastic nanotubes

Abi — Mon, 27 Nov 2006 11:47:06 +0000

First, the nano-knife (via slashdot):

A prototype microtome knife for cutting ~100 nm thick slices of frozen-hydrated biological samples has been constructed using multiwalled carbon nanotubes (MWCNT). A piezoelectric-based 3-D manipulator was used inside a Scanning Electron Microscope (SEM) to select and position individual MWCNTs, which were subsequently welded in place using electron beam-induced deposition (EBID).

The device employs a pair of tungsten needles with provision to adjust the distance between the needle tips, accommodating various lengths of MWCNTs. We have performed experiments to test the breaking strength of the MWCNT in the completed device using an atomic force microscope (AFM) tip. An increasing force was applied at the midpoint of the nanotube till the point of failure, which was observed in-situ in the SEM.

Next, the superplastic nanotubes of carbon:

The theoretical maximum tensile strain — that is, elongation — of a single-walled carbon nanotube is almost 20%, but in practice only 6% is achieved. Here we show that, at high temperatures, individual single-walled carbon nanotubes can undergo superplastic deformation, becoming nearly 280% longer and 15 times narrower before breaking. This superplastic deformation is the result of the nucleation and motion of kinks in the structure, and could prove useful in helping to strengthen and toughen ceramics and other nanocomposites at high temperatures.

Kinship with the cosmos

Abi — Mon, 27 Nov 2006 09:42:40 +0000

Are you in the mood for something truly inspiring, exciting and, um, spiritual? If not, why, you really ought to be! If yes, watch this short video of a speech by Neil deGrasse Tyson.

Awesome!

Different meanings of the word ‘replicate’

Abi — Thu, 31 Aug 2006 11:16:36 +0000

In the rough-and-tumble world of science, disputes are usually settled in time, as a convergence of evidence accumulates in favor of one hypothesis over another. Until now.

On April 10 economist John R. Lott, Jr., formerly of the American Enterprise Institute, filed a defamation lawsuit against economist Steven D. Levitt of the University of Chicago and HarperCollins, the publisher of Levitt’s 2005 book, Freakonomics. At issue is what Levitt meant when he wrote that scholars could not “replicate” Lott’s results …

That’s from Michael Shermer’s Skeptic column in Scientific American. Shermer is “executive director of the Skeptics Society, bold debunkers of all things supernatural”, according to Salon which has a long interview with him [free, if you are willing to watch an ad]. I don’t know if artificial intelligence would be considered ’supernatural’, but here is an interesting article in the Skeptic magazine (flagship of the Skeptics Society) debunking the lofty claims made by AI enthusiasts.

The Oscars of Indian Science: 2006 Edition

Abi — Thu, 31 Aug 2006 07:08:46 +0000

Yes, the Shanti Swarup Bhatnagar (SSB) Prizes have been announced for the year 2006. As I said in my post last year, the SSB Prizes are the most prestigeous in India because (a) they represent peer recognition, and (b) they are rare (just one or two in each field). They do come with some money, but at Rs. 200,000 or about $5,000, it’s not much (but certainly nice!).

I’m pleased to note that Prof. S. Sampath, a colleague in the Department of Inorganic and Physical Chemistry, is among the SSB Prize winners [Congratulations, Sampath!]. He has won one of the two Prizes for Chemical Sciences; Dr. K George Thomas (RRL, Trivandrum) has won the other.

The two SSB Prizes for engineering go to Dr. Ashish Lele (Complex Fluids and Polymer Engineering, National Chemical Laboratory, Pune) and Dr. Sanjay Mittal (Aerospace Engineering, IIT-K).

I have to fault the Council of Scientific and Industrial Research (CSIR), the organization that awards these Prizes, for giving just the barest of details about the awardees. Is it so difficult to put together a news story that has details about each awardee’s important contributions? Wouldn’t it be nice — offering a higher profile for the Prize winners, and more information for the others — if full citations are available on the CSIR website? Currently, all that it offers is this press release [pdf] which deserves a prize for minimalism.

BMQ

Abi — Thu, 24 Aug 2006 13:33:56 +0000

A quick note to tell you — particularly those of you in Bangalore — about the Bangalore Materials Quiz (BMQ), an annual event organized by us for the students of Classes XI and XII. As the name suggests, BMQ covers all aspects of materials: their physics, chemistry, production, processing, properties (mechanical, thermal, electrical, magnetic, optical, …), applications and use.

I have created the BMQ blog which will be used to both disseminate information and coordinate our team’s activities.

BMQ is organized almost entirely by the wonderful graduate students of our Department. They orchestrate all aspects of the event, with some minimal guidance (and cheering from the sidelines) from me. This is the tenth year since I took over the responsibility of running this show, and I have met some of the brightest students (one of them runs this blog) through it.

BMQ is not a mega event; we usually get about 25 teams (of two each) every year. This year, we hope to attract 50 teams. On the other hand, we aren’t set up to handle a large number of teams either; so 50 is the hard limit!

The Prize we offer is admittedly small — books worth about Rs. 500 for each student! But the top two teams from BMQ get to take part in a grander event with bigger prizes at stake (see the blog for details).

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Well, if you know anyone in Bangalore-based schools (higher secondary schools and pre-university colleges) who might be interested in BMQ, do please spread the word. Many thanks in advance.

Manhattan Project in energy saving technologies

Abi — Fri, 11 Aug 2006 11:23:52 +0000

Wired has an article (with links) about on-going research in energy-saving technologies in MIT. Check this one out!

The research is applying new materials, new technologies and new ideas to radically improve an old concept — thermophotovoltaic (TPV) conversion of light into electricity. Rather than using the engine to turn a generator or alternator in a car, for example, the new TPV system would burn a little fuel to create super-bright light. Efficient photo diodes (which are similar to solar cells) would then harvest the energy and send the electricity off to run the various lighting, electrical and electronic systems in the car.

Such a light-based system would not replace the car’s engine. Instead it would supply enough electricity to run subsystems, consuming far less fuel than is needed to keep a heavy, multi-cylinder engine running, even at low speed. Also, the TPV system would have no moving parts; no cams, no bearings, no spinning shafts, so no energy would be spent just to keep an engine turning over, even at idle.

An explosive commentary on the status of women in science

Abi — Thu, 13 Jul 2006 15:12:20 +0000

When I was 14 years old, I had an unusually talented maths teacher. One day after school, I excitedly pointed him out to my mother. To my amazement, she looked at him with shock and said with disgust: “You never told me that he wasblack”. I looked over at my teacher and, for the first time, realized that he was an African-American. I had somehow never noticed his skin colour before, only his spectacular teaching ability. I would like to think that my parents’ sincere efforts to teach me prejudice were unsuccessful. I don’t know why this lesson takes for some and not for others. But now that I am 51, as a female-to-male transgendered person, I still wonder about it, particularly when I hear male gym teachers telling young boys “not to be like girls” in that same deroga-tory tone.

[...]

Here are a few examples of bias from my own life as a young woman. As an undergrad at the Massachusetts Institute of Technology (MIT), I was the only person in a large class of nearly all men to solve a hard maths problem, only to be told by the professor that my boyfriend must have solved it for me. I was not given any credit. I am still disappointed about the prestigious fellowship competition I later lost to a male contemporary when I was a PhD student, even though the Harvard dean who had read both applications assured me that my application was much stronger (I had published six high-impact papers whereas my male competitor had published only one). Shortly after I changed sex, a faculty member was heard to say “Ben Barres gave a great seminar today, but then his work is much better than his sister’s.”

This explosive commentary in Nature [1] by Ben Barres, a neurobiologist at Stanford, is going to be discussed quite widely. There will be a lot of spin on either side, but there’s nothing like the original. Do read Ben Barres’ very personal commentary; you will learn and understand a lot more about ‘innate differences’ (see another quote below) and ‘discrimination’ from just this one source than from the tons of spin-filled meta-commentary that’s sure to follow.

In an accompanying piece (in a side bar, I think), this is what Barres says:

As a transgendered person, no one understands more deeply than I do that there are innate differences between men and women. I suspect that my transgendered identity was caused by fetal exposure to high doses of a testosterone-like drug. But there is no evidence that sexually dimorphic brain wiring is at all relevant to the abilities needed to be successful in a chosen academic career. I underwent intensive cognitive testing before and after starting testosterone treatment about 10 years ago. This showed that my spatial abilities have increased as a consequence of taking testosterone. Alas, it has been to no avail; I still get lost all the time when driving (although I am no longer willing to ask for directions). There was one innate difference that I was surprised to learn is apparently under direct control of testosterone in adults — the ability to cry easily, which I largely lost upon starting hormone treatment. Likewise, male-to-female transgendered individuals gain the ability to cry more readily. By far, the main difference that I have noticed is that people who don’t know I am transgendered treat me with much more respect: I can even complete a whole sentence without being interrupted by a man.

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[1] The link is to Nature’s website, and if it’s pay-walled, take a look at this story [via].

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Cross-posted at nanopolitan, my main blog.

Nikola Tesla

Abi — Tue, 11 Jul 2006 08:43:18 +0000

Couturnix has a great post — no, make that an absolutely great post — on Nikola Tesla in celebration of the latter’s 150th birthday on July 10. You’ve got to check out that post to see why I’m amazed …

Still, at least the first two commenters on that post were left rather underwhelmed by Couturnix’s link-fest. Hmmm, such is life …

Los Alamos

Abi — Sun, 09 Jul 2006 07:16:27 +0000

It has been quite a while since I noted the Los Alamos scientists’ revolt (through a blog!) that forced the then director to resign. The Economist updates us on what’s happening at Los Alamos.

… At the beginning of June the University of California, which had run Los Alamos since the days of the Manhattan Project, ceded control to a consortium known as Los Alamos National Security. Though the university remains one of the consortium’s members, it will now share what bouquets and brickbats come Los Alamos’s way with three firms that make a lot of their money as military contractors. These are Bechtel and Washington Group International, two large engineering and construction companies, and BWX technologies, a concern that specialises in managing nuclear facilities.

Unlike the university, the new consortium will be aiming to make a decent profit from its activities. It is also thought likely to change the emphasis of the laboratory from research (in a wide range of subjects, not all of them to do with defence, let alone nuclear weapons), to the more mundane business of making the detonators of nuclear warheads.

The consortium is making reassuring noises. According to Jeff Berger, its director of communications, “There is a popular misconception that we’re out to change the lab’s mission.” Nevertheless, many of Los Alamos’s researchers sense a shift of direction. Indeed, quite a few have left. …