My friend Bryan points out another good one:

Even though the Nobel Prizes can be pretty surprising sometimes — did anyone guess Geim and Novoselov last year for the Physics prize? — it’s still fun to try to predict who will win.

Several of the recent Physics prizes have been for applied solid-state things (giant magnetoresistance in 2007, fiber-optics/CCDs in 2009, graphene in 2010). If this trend continues, John and Yablonovitch are good contenders for their work in photonics, or Ohno for his work on dilute magnetic semiconductors, or Haider, Rose, and Urban for their work on electron microscopy. If the committee decides that it’s time for something new, I think Aspect, Clauser, and Zeilinger are good contenders for their work on quantum entanglement, or, as I’ve previously predicted, Aharonov and Berry for their work on quantum topological and geometrical phases.

The Chemistry prize doesn’t seem to follow a trend, which makes it more difficult to predict. Some strong contenders are: Zare for his work using lasers for spectroscopy; Moerner for his work on single-molecule spectroscopy; and Matyjaszewski for developing ATRP.

So, completely randomly, my predictions for this year are:

• Physics: Aharonov and Berry; backup prediction: Haider, Rose, and Urban
• Chemistry: Zare; backup prediction: Matyjaszewski

In principle, though, you just need anything with carbon. An impure source could be placed on the frontside of the metal film; the carbon atoms would then diffuse to the backside of the film, forming graphene, while the impurities would stay put and later be etched away. This amusing paper from Jim Tour’s group does a nice job of highlighting this point. They use CVD to grow high-quality graphene on a copper foil using, among other things, feces from a miniature Dachsund, a cockroach leg, grass, and a short-bread flavored Girl Scout cookie. (The authors do not comment on how different flavors affect their results. I personally prefer my graphene thin-mint flavored.)

A wealth of work has shown that, surprisingly, seemingly uncoated gas bubbles of sizes ~ tens-hundreds of nanometers can form and remain stable on immersed solid surfaces for over a day, 100,000,000,000 times longer than classical theories predict; these are fittingly called “surface nanobubbles”. What’s also puzzling is that the angle such a nanobubble makes with the surface it sits on doesn’t depend too strongly on what the surface is made of, unlike typical bubbles and fluid droplets.

These problems can be partly resolved if the gas molecules in the bubble don’t bounce off each other, randomizing each others’ positions and velocities as they do in a typical gas; instead, if the gas behaves as a non-interacting Knudsen gas (as can be the case for small enough bubbles), a non-random directed flow of gas out of the bubble can result from the gas molecules bouncing off the solid surface. This flowing gas sweeps the surrounding fluid along with it, causing a strong flow, or a “nano-jet”, away from the bubble (as depicted in the image). This flow eventually has to circulate back on itself, sweeping the dissolved gas back to the solid surface, where it can re-enter the bubble. So a surface nanobubble may be in a state of dynamic equilibrium — even though the gas inside the bubble dissolves out into the fluid, the fluid continuously pushes the gas back to the bubble, and it re-enters the bubble.

Schematic of the strong circulating flow (arrows) set up in a fluid (blue) by a surface-attached nanobubble (yellow); from Seddon et al.

In this recent paper from Detlef Lohse’s group, Seddon et al. use atomic force microscopy — essentially a jiggling nano-sized cantilever — to measure the forces around a surface nanobubble. Intriguingly, they measure an outward force around the nanobubble that extends several hundred nanometers away from it, and they confirm that this force doesn’t have an electrostatic origin. They don’t list the amplitude of the oscillation they use — if the cantilever jiggles too much, it could just be deforming the nanobubble, which would then push back and exert a force similar to what they see — but assuming their oscillation amplitude is small enough to rule out this effect, their data seem to be a nice bit of evidence in support of the “nano-jet” theory of nanobubble stability. The most striking thing of all is, when they work out what fluid speed their measured forces correspond to, they find that the nano-jet created by their tiny nano/micro-sized bubble is a shocking ~3m/s. Imagine — the bubble keeps pushing the fluid around it out at a speed 30,000,000 times its height every second for over 12 hours! Crazy.

Of course, the puzzle of nanobubble stability isn’t fully resolved. Caveat #1: as every experimentalist knows, no matter how well you try to clean a solid surface/liquid solution, there will always be trace bits of crap floating around. These could be acting as surfactants and coating the nanobubble, potentially imparting some stability — but what exact role do they play here? Caveat #2: this theory requires a directed flow of the gas inside the bubble out of it; this results from the gas pushing against the solid surface. However, in some cases, nanobubbles not attached to a surface can also be stable (see references 7 and 8 here) — in this case it’s not so clear how the nano-jet theory applies.

Here are a few gems:

• Talking about his Ph.D. thesis: All I can say is that the stuff was as interesting at that time as it sounds to the reader today… Web of Science soberly reveals that [my] papers were cited twice, by coauthors only. The subject was dead a decade before I even started my Ph.D.
• On being resourceful and working hard: There is no such thing as bad samples; there are only bad postdocs/students. Search carefully and you always find something new… The fact that Ernie and I are most proud of is that many groups around the world have more expensive facilities but our [Nanotechnology] Centre continuously, since 2003, has been producing new structures and devices. We do not have here a posh horse that is for show, but rather a draft horse that has been working really hard.
• On trying silly experiments: With [a fuzzy] idea in mind and, allegedly, on a Friday night, I poured water inside the lab’s electromagnet when it was at its maximum power. Pouring water over equipment is certainly not a standard scientific approach, and I cannot recall why I behaved so “unprofessionally.” Apparently, no one tried such a silly thing before, although similar facilities existed in several places around the world for decades. To my surprise, water did not end up on the floor but got stuck in the vertical bore of the magnet. Humberto Carmona, a visiting student from Nottingham, and I played for an hour with the water by breaking the blockage with a wooden stick and changing the field strength. As a result, we saw balls of levitating water. This was awesome… The levitation experience was both interesting and addictive. It taught me the important lesson that poking in directions far away from my immediate area of expertise could lead to interesting results, even if the initial ideas were extremely basic. This in turn influenced my research style, as I started making similar exploratory detours that somehow acquired the name “Friday night experiments.” The term is of course inaccurate. No serious work can be accomplished in just one night. It usually requires many months of lateral thinking and digging through irrelevant literature without any clear idea in sight. Eventually, you get a feeling—rather than an idea—about what could be interesting to explore. Next, you give it a try and, normally, you fail. Then, you may or may not try again. In any case, at some moment you must decide (and this is the most difficult part) whether to continue further efforts or cut losses and start thinking of another experiment. All this happens against the backdrop of your main research and occupies only a small part of your time and brain.
• On picking something to work on: Searching the literature for [brilliant ideas] is not a good idea at all. At the start of a new project, a couple of decent reviews usually do the job of making sure that one does not reinvent the wheel. The alternative can be truly detrimental. I have met many promising researchers who later failed to live up to their promise because they wasted their time on searching literature, instead of spending it on searching for new phenomena. What’s more, after months of literature search, they inevitably came to the same conclusion: Everything they planned had been done before. Therefore, they saw no reason to try their own ideas and, consequently, began a new literature search. One should realize that ideas are never new. However brilliant, every idea is always based on previous knowledge and, with so many smart people around, the odds are that someone somewhere had already thought of something similar before. This should not be used as an excuse for not trying because local circumstances vary and, moreover, facilities change with time. New technologies offer a reasonable chance that old failed ideas may work unpredictably well the next time around.

Steel sphere (a) below its Leidenfrost temperature and (b-c) above its Leidenfrost temperature; from Vakarelski et al.

You need to exert a force on an object to push it through a fluid or gas at a constant speed: this is typically because of hydrodynamic drag. A great deal of effort goes into minimizing drag. Vakarelski et al. have come up with an elegantly simple way of reducing the drag on an object moving through a fluid at sufficiently large speeds: heat it up.

In particular, they show that heating a metallic sphere above its Leidenfrost temperature (the temperature above which a thin vapor layer forms on the object’s surface) causes the drag coefficient to decrease by up to a factor of 5 — pretty striking. They suggest that the vapor layer at the sphere surface prevents the surrounding fluid from “sticking” to the sphere’s surface, as is typically the case; as a result, the flow separates from the sphere further downstream (as shown in the image) and changes the pressure distribution in the fluid.

Previous work has typically assumed that hummingbirds feed through capillary action, the same process by which a thin glass tube will spontaneously imbibe water. Unfortunately, this hypothesis is inconsistent with a number of basic observations; for example, capillarity should favor lower sugar-content, and hence lower viscosity, nectar, at odds with hummingbirds’ natural preference.

In this beautiful series of experiments, Rico-Guevara and Rubega overturn this picture. Using high-speed imaging and by cleverly constructing transparent artificial flowers, they imaged the hummingbird tongue tip during feeding. This tip doesn’t passively suck up nectar through capillary action, as previously thought. Rather, it changes its shape, opening up and trapping a packet of nectar within it. The tongue subsequently retracts and the packet of nectar is ingested — all in a period of ~50 milliseconds!