Back (no, really)

It’s been a while since I last posted, and I’ve been up to quite a bit since then. For starters, I’m officially done with undergrad - apparently now I’m a bachelor of arts and a master of science.

In other news, I finally (!) decided on a grad school - this fall, I will be moving on from Penn and starting my Ph.D. in physics at Harvard. I actually packed up and moved to Cambridge a week ago, and have been getting settled and starting work in my new lab - I’m doing biophysics work in Dave Weitz’s group, which is really exciting. (More details later…)

Physics bloggers have actually been shuffling around quite a bit: for example, fliptomato has come back to the U.S. from the U.K., while in a happy coincidence Mark Trodden will be leaving Syracuse for… Penn!

A nice little sidenote is that one of my main papers stemming from some of the work I did while at Penn was accepted not too long ago - watch out for it in Nano Letters sometime soon…

And lastly, moving has given me a chance to organize some of the clutter in my life. In that spirit, I’ve decided to give my new personal webpage and this blog a quick makeover.

Wrapping up the summer

Crazily enough, the summer’s over. I’ve been bitten by the research bug, which means that I’m not as enthusiastic about taking classes as I once was, although they all look very interesting and useful. In particular, balancing nocturnal data-taking sessions with going to class/taking tests has never been my forte; and it’s tougher now, what with graduate school applications and pesky standardized tests.

Anyway, the past month’s pretty much consisted of finishing up taking/analyzing data for this paper I’ve been working on, as well as actually writing it. When I started out, I thought my data was somewhat interesting. Thanks to an excellent theorist collaborator, we have a good sense of what’s going, and it’s more interesting than I thought (which is always nice).

I did take a little vacation and went to the Princeton Center for Complex Materials (PCCM) summer school on condensed matter physics (unfortunately they don’t have their talks online yet). This is the second year that I’ve gone; hopefully there will be more. Two talks in particular resonated with me - Philip Kim’s talk on electronic transport in graphene, and Paul Chaikin’s talk on some aspects of colloidal physics. The graphene talk was of particular interest from a technical point of view. While it was very cool, given the nature of my work it dealt with things that I’m very familiar with and/or think about regularly, so I’m not going to describe it here.

On the other hand, Chaikin’s talk was interesting to me from a more conceptual point of view. I’ve encountered some notions of soft matter physics before, but his talk really drove home how exciting some of the things going on in that field are. He started off discussing his recent highly-publicized work on packing hard particles (interesting not only for studying granular materials or phase transitions, but also for designing three-dimensional colloidal photonic crystals) - the point being that random ellipsoid packings (like those formed using M&M’s) can pack denser than ‘conventional’ random jammed packings, even potentially approaching the FCC packing fraction of 0.74, because of their added rotational degrees of freedom. This, in turn, may help understand how glasses form. For me it wasn’t the story but how they fleshed it out (experimentally and using simulations) that was the exciting part.

Unfortunately I had an experiment to finish up and had to miss Chaikin’s second talk, on replication and self-assembly using colloids; his third talk on ‘random organization’ describing some work by David Pine (at NYU) and Jerry Gollub (at Haverford, but also affiliated with Penn) was equally good. He started out discussing reversibility in viscous liquids - that is, the fact that low Reynolds number shear flows are time reversible, a notion I first came across in an excellent article by Brewer and Hahn describing NMR spin echos. There’s a classic demonstration of this phenomenon by G. I. Taylor using a cylindrical Couette cell, although I couldn’t find a nice movie online. Anyway, similar experiments have been performed involving tracking small dyed spheres placed in the liquid while shearing them. Interestingly, while the system remains reversible for low enough strain amplitude, for whatever reason (e.g. collisions/chaos), hydrodynamic irreversibility sets in very quickly as the strain amplitude is increased. Really striking stuff. At the end of the day, colloids really are great systems to work with: they’re easy to make, specific and controllable (e.g. using DNA sticky ends or electric fields), and exhibit all kinds of interesting condensed matter phenomena.

Now that I think of it, the PCCM summer school was so enjoyable partly because it filled in the void left by the lack of regular talks and seminars over the summer. Thankfully, now that the new semester has started, that void has been filled again. Most recently, Jack Harris (from Yale) gave a talk on coupling light and MEMS using radiation pressure, something I don’t know much about. Part of the experimental challenge is in using the right structures; interestingly, a route his group is taking is to use silicon nitride membranes with holes drilled in them. I find this particularly amusing because our group has used (indeed, I made some my first year of research) similar porous membranes to image carbon nanotubes or nanotube-derived structures (like ‘peapods’) using TEM - it never occurred to me that they could be used for such a different purpose.

Anyway, writing this post has been very relaxing; now it’s time to get back to work…

‘Hard’ measurements, ’soft’ materials

So it’s been what, a little less than two months since I last posted? I tend to work on many projects at once - some are ones I’ve been plugging away at for a while, while others are “let’s see what happens” experiments that I work on when I get the time, motivated by some half-brained idea. In particular, I’ve made significant progress on a project of the latter category, and the month-and-a-half has been spent making samples, furiously taking and analyzing data, trying to figure out what it means/delving through the literature, &c. - and of course, effectively disrupting any prospects of sleep or studying for pesky standardized tests. And making headway on my other projects, too. The good news is that I, for one, find the data pretty exciting.

(Oh, and moving to my sweet new apartment, which apparently scores a very respectable 98/100 on the walkability scale. Not too bad, especially given the relatively low rent.)

Anyway, when I haven’t been concentrating on my research, I’ve been reading up on things like organic semiconductors and STM modification of molecules (I suppose what one could call ‘hard’ condensed matter measurements of ’soft’ materials, although admittedly some of my own research falls into this genre). I find people like Paul Chaikin, Heinrich Jaeger and George Gruner particularly fascinating since they seem to be actively doing this kind of research in addition to hard condensed matter physics of the more ‘traditional’ kind (superconductivity/correlated electron systems…). I wonder how many other PIs do this kind of thing?

And of course, two new additions to the reading list: “charge transfer on the nanoscale: current status“, and “electrostatic modification of novel materials” - both hefty reviews of topics relevant to this post.

Also: Heinzel’s book on mesoscopic physics is a new addition to my list of the greatest books of all time - in particular, its clarity is unmatched by many other books I’ve come across on the subject.

A few thoughts

Clearly blogging has slowed down now that I’m back into the swing of research. Here are a few minor non-research things that have transpired…

Free coffee? While attempting to read a thesis by a professor here, I came across an interesting line in the acknowledgments in which he thanked “the labours of the coffee and tea pickers whose efforts kept me awake long enough to produce this document”. Here’s a thought: athletes and celebrities receive inordinate amounts of free stuff - and of course, money - to endorse certain products (I presume). Why can’t physicists and other scientists do the same? For example, if Red Bull or La Colombe ran full-page ads in Nature along the lines of “Ed Witten drinks Red Bull - do you?” or “Andrew Wiles: turning La Colombe coffee into theorems”, I’m sure their sales would increase significantly. (I venture that no other single demographic consumes more caffeine.) And of course, they could give the individual/individual’s department free coffee and/or funding in return. It’s a win-win situation.

De Gennes dies: There’s not much I can say that hasn’t already been said (see this NYT article, for example). I’ve had the pleasure of delving into two of his books, the seminal Physics of Liquid Crystals - note to self: learn more about the connections between superconductors and liquid crystals - and the perhaps lesser-known Petit Point: A Candid Portrait on the Aberrations of Science. The latter is a rather interesting book, with very short chapters describing fictional characters based on scientific individuals. The sole reviewer of the book on Amazon claims to be able to identify Benoit Mandelbrot, Brian Josephson and Bernd Matthias in the various characters; my own hunch is that the chapter on “Chazot” is autobiographical in nature (the last line, “…in the end, Chazot’s real vocation is perhaps to give talks to high school students”, pretty much gives it away).

Blog-related: Henry Cate of the Why Home School blog is kicking off a carnival of space, which is a great idea (don’t know what a blog carnival is? See here.) Here are the archives, here is this week’s carnival, here’s the announcement, and most importantly - here’s how to submit a post for inclusion. Go for it!

And, in other news, Arunn of n0noscience and Rod of Perfectly Reasonable Deviations have both tagged me as being a ‘thinking’ blogger, which is a wonderful honor. I’m supposed to link to five other blogs that make me think, but it’s tough; the best I can do is link to the list of blogs I follow when I can since they’re all interesting.

Information theory: Cover and Thomas’ Elements of Information Theory (2nd ed.) is a really, really good book. Sadly I haven’t been able to read as much of it as I’ve wanted to, but it’s been a fascinating fusion of mathematics, physics, and computer science.

Talks Part 3: Biomaterials

Another talk that was particularly interesting was Angela Belcher’s Grace Hopper lecture on “Genetic Control of the Synthesis and Assembly of Materials for Electronics and Energy”. I’m not going to post much on it save for a number of references, because I’ve been aware of a lot of her group’s work for a good deal of time now. In general, what they do is try to combine man-made fabrication tools and the specificity inherent in living systems (via millions of years of evolution) to figure out easy, controllable, environmentally-friendly ways to make new materials for a variety of purposes. I was particularly struck by her emphasis on the simplicity of everything they do - if it can’t be transferred to industry or undergrad labs within several years, they won’t do it, which is an interesting philosophy. Anyway, one of the particularly cool things Prof. Belcher’s group has come up with recently is the use of viruses to direct the formation of nanowires, and they’ve been working to use them to make things like self-assembling, cheap and efficient Li-ion batteries. This kind of work definitely appeals to the part of me that likes science because of all the neat things that it enables us to make. Anyway, here are some of her publications that I’ve found most useful:

- B. D. Reiss et al., “Biological Routes to Metal Alloy Ferromagnetic Nanostructures“, Nano Lett. 4 1127 (2004).
- S. Jaffar et al., “Layer-by-Layer Surface Modification and Patterned Electrostatic Deposition of Quantum Dots“, Nano Lett. 4 1421 (2004).
- P. J. Yoo et al., “Spontaneous assembly of viruses on multilayered polymer surfaces“, Nature Materials 5 234 (2006).
- K. T. Nam et al., “Virus-Enabled Synthesis and Assembly of Nanowires for Lithium Ion Battery Electrodes“, Science 312 885 (2006).
- Y. Huang et al., “Programmable Assembly of Nanoarchitectures Using Genetically Engineered Viruses“, Nano Lett. 5 1429 (2005).
- C. Mao et al., “Viral assembly of oriented quantum dot nanowires“, PNAS 100 6946 (2003).