All posts by Abi

About Abi

My name is T. A. Abinandanan, and I am a professor of Materials Engineering at the Indian Institute of Science, Bangalore.

Quote: Beginner’s Mind and Expert’s Mind

In the beginner’s mind, there are many possibilities. In the expert’s mind, there are few.
— Shunryu Suzuki in Zen Mind, Beginner’s Mind

Found here.

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Liquid Metal? In A Watch?

Yes. In a watch. Not just any watch, but an Omega.

In any case, watch. I mean the video at that link, and you’ll love the slogan: “Sometimes, the most unlikely partnerships are the most enduring.” And I guess we could add, “the most expensive.”

Here’s the short description from that page on the bulk metallic glass that goes by its trade name “Liquidmetal®”:

Liquidmetal®: seamless bonding, remarkable hardness

The Liquidmetal® alloy is an amorphous metal – a metallic material with a disordered, non-crystalline atomic structure. Its fusion temperature is half that of conventional titanium alloys but when it is cooled, its hardness is three times as great as that of stainless steel. Its amorphous structure allows it to bond seamlessly with the ceramic bezel.

The Liquidmetal® is a bulk metallic glass alloy consisting of five elements: zirconium, titanium, copper, nickel and beryllium. A bulk metallic glass can, by virtue of its low critical cooling rate, be formed into a structure with a thickness of more than a tenth of a millimetre. Zirconium is an important constituent part both of the Liquidmetal® alloy and of the ceramic material which is made of zirconium dioxide (Zr02).

Thanks for the pointer to my friend and colleague Ram (Prof. U. Ramamurty), who is well known for his studies of mechanical behaviour of bulk metallic glasses.

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BTW, this blog has had a chance to post about Liquidmetal® sometime ago.

Golden Trivia

From Who’s Got All The Gold, And Who’s Mining It:

All Gold Ever Mined – The total amount of gold ever mined is estimated to be worth around US$5 trillion.

How Gold is Used – You might have though (like me) that most of the gold in the world stored in bank vaults and lock-boxes? Actually, 78 % of the worlds’ gold is made into jewelery. Other industries, mostly electronics, medical, and dental, require about 12%. The remaining 10% of the yearly gold supply is used in financial transactions.

Materialia Indica

Just a quick note — after a dormant period of over 16 months! — to tell you that I have started blogging at Materialia Indica, an India-centric group blog by and for materials science folks — academics, researchers, post-docs, grad and undergrad students. See the About page for details. [Update (1 June 2009): Materialia Indica now has a new, more spacious and more feature-rich home at Ning, which offers a complete suite of networking and community-building features that we have always wanted (and our blog lacked). In particular, becoming a member and starting a discussion is far easier for all the members of a community in a social network than in a blog. Hence the move to Ning.

If you are interested in materials science/engineering education and research in India, Materialia Indica is the place to be. Come on in and join us. You don’t need a special invitation from anyone; just click on the ‘sign-up’ link, fill in the details, and you are in!]

As of now, my co-bloggers are Guru (M.P. Gururajan, IIT-D) and Phani (G. Phanikumar, IIT-M).

We would like to expand our team. If you are interested — or, if you know someone who might be interested, let us know through the contact form on the Contributors page.

Now, this blog can go back to being silent …9

Some links …

Exon points us to this Science Roll post with a compilation of science-oriented video archives.

Philip Ball has a post recounting the history (and the key person) behind the development of goggles that filter out UV and IR radiation.

Guru points us to some of the classic papers from the previous centuries that Philosophical Magazine has published on its website along with some commentary.

This article in the Hindu is about a study on the saddle point configuration for nucleation of a bubble in superheated water. It claims that this study overturns a conventional view; I am yet to figure out how!

Liquid Metal

Check out this video that compares the elastic properties — in particular, the resilience or the amount of stored elastic energy — of three materials: an amorphous alloy, stainless steel and titanium. The video is from Liquidmetal Technologies, a California based company founded to commercialize the research on amorphous alloys (or metallic glasses) conducted at Caltech by Prof. William L. Johnson. Do check out the Liquidmetal website; there is a wealth of materials-oriented information (including applications of amorphous alloys) there.

iMechanica links

The iMechanica site is a treasure. The good folks there post not only their recent papers and preprints, but also stuff that’s of interest to a general audience as well. Let me just link to a bunch of these general purpose things that appeared there recently:

In addition, there are course notes on offer:

Here are some links that should interest materials people:

And finally, here are some tips for finding information on iMechanica:

MIT’s progress in making synthetic spider silk

From this report [via slashdot]:

“If you look closely at the structure of spider silk, it is filled with a lot of very small crystals,” said Gareth McKinley, a professor of mechanical engineering and part of the group that devised the new method of producing the material.

“It’s highly reinforced.”

The secret of spider silk’s combined strength and flexibility, according to scientists, has to do with the arrangement of the nano-crystalline reinforcement of the silk as it is being produced—in other words, the way these tiny crystals are oriented towards (and adhere to) the stretchy protein.

Emulating this process in a synthetic polymer, the MIT team focused on reinforcing solutions of commercial rubbery substance known as polyurethane elastomer with nano-sized clay platelets instead of simply heating the mixing the molten plastics with reinforcing agents.

Some materials links

Invisible electronics.

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

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.

Anatomy of a scientific fraud

Just drop everything, and read the NYTimes story (mixed with some analysis) about Eric Poehlman’s fraud which made him “only the second scientist in the United States to face criminal prosecution for falsifying research data.” Here’s the opening paragraph:

On a rainy afternoon in June, Eric Poehlman stood before a federal judge in the United States District Court in downtown Burlington, [Vermont]. His sentencing hearing had dragged on for more than four hours, and Poehlman, dressed in a black suit, remained silent while the lawyers argued over the appropriate sentence for his transgressions. Now was his chance to speak. A year earlier, in the same courthouse, Poehlman pleaded guilty to lying on a federal grant application and admitted to fabricating more than a decade’s worth of scientific data on obesity, menopause and aging, much of it while conducting clinical research as a tenured faculty member at the University of Vermont. He presented fraudulent data in lectures and in published papers, and he used this data to obtain millions of dollars in federal grants from the National Institutes of Health — a crime subject to as many as five years in federal prison. Poehlman’s admission of guilt came after more than five years during which he denied the charges against him, lied under oath and tried to discredit his accusers. By the time Poehlman came clean, his case had grown into one of the most expansive cases of scientific fraud in U.S. history.

The following paragraph, which appears in the second part of the long article, sums up the problem:

The scientific process is meant to be self-correcting. Peer review of scientific journals and the ability of scientists to replicate one another’s results are supposed to weed out erroneous conclusions and preserve the integrity of the scientific record over time. But the Poehlman case shows how a committed cheater can elude detection for years by playing on the trust — and the self-interest — of his or her junior colleagues.

Two other high profile cases of fraud in recent times — Hendrik Schön and Hwang Woo Suk — also make an appearance in the NYTimes story:

Most people involved in Poehlman’s case say that fraud as extensive as his represents an uncommon pathology, similar to what drove the South Korean scientist who claimed to have cloned human stem cells or the Lucent Technologies physicist who falsified extensive amounts of nanotechnology data. More frequent, according to a study published in Nature in June 2005, are smaller lapses in ethical judgment, like failing to present data that contradicts your previous research or inappropriately assigning author credit. Brian Martinson, who conducted that study with colleagues from the University of Minnesota, suggests that those gray areas, which many scientists inhabit at one time or another during their careers, portend a greater ailment for the scientific process. Minor transgressions, largely undetected and easily rationalized, can build up like plaque, compromising scientific integrity over time.

Do read the whole thing. It’s long, but well worth it.

Mechanics of superheroes

The spider-‘silk’ produced by Spiderman about as thick as his arm — it’s more like ‘spider-rope’. But, does it really need to be that thick? No, says this SciAm article on the wonderful combination of mechanical properties of real spidersilk.

The different silks have unique physical properties such as strength, toughness and elasticity, but all are very strong compared to other natural and synthetic materials. … The movie Spider-Man drastically underestimates the strength of silk�real dragline silk would not need to be nearly as thick as the strands deployed by our web-swinging hero in the movie.

Here’s a quick description of what makes up one of the several forms of spidersilk:

Dragline silk is a composite material comprised of two different proteins, each containing three types of regions with distinct properties. One of these forms an amorphous (noncrystalline) matrix that is stretchable, giving the silk elasticity. When an insect strikes the web, the stretching of the matrix enables the web to absorb the kinetic energy of the insect�s flight. Embedded in the amorphous portions of both proteins are two kinds of crystalline regions that toughen the silk. Although both kinds of crystalline regions are tightly pleated and resist stretching, one of them is rigid. It is thought that the pleats of the less rigid crystalline regions not only fit into the pleats in the rigid crystals but that they also interact with the amorphous areas in the proteins, thus anchoring the rigid crystals to the matrix. The resulting composite is strong, tough, and yet elastic.