Land Mine Detection With Stuff That Smells Good

Punta Espora, Chile, Tierra del Fuego side of the Strait of Magellan - minefield warnig near the ferry terminal

At the March meeting of the American Physical Society, an abstract was presented entitled “Detection of Nitro aromatics via fluorescence quenching of pegylated and siloxanated 4, 8-dimethylcoumarins”.

The BBC reported that this study utilized curcumin, which is found in the spice turmeric and is one of the key ingredients in many curry powders.

Now, I wasn’t at the meeting so I may be wrong, but the abstract does not describe using curcumin, but coumarins. Coumarin is also a fragrant chemical compound, but it is not found in turmeric. It is actually used as a rodenticide and was banned as a food additive in the United States in 1954.

If I’m lucky enough to have a reader who knows more about this work, or was at the conference and saw this talk, I would very much appreciate a clarification. In any case, the research is still pretty interesting.

The abstract described the work of a team of researchers at the University of Massachusetts Lowell. The group reported their research into using optical sensors to detect chemical explosives, such as those found in land mines.

Optical sensors work by reacting the molecules released into the air of the chemical explosive. The optical properties of the sensor material changes after interacting with the explosive. Measuring these changes in optical properties is called fluorescence spectroscopy.

The group created co-polymers and tested their use in fluorescence quenching, which means that when you shine a light on these polymers in the presence of explosives such as trinitrotoluene (TNT), the light given off by them would dim.

The BBC also reports that

The team, which is funded in part by the US government, is already in discussions with a company to develop the technique into a portable detector device.

which, given the huge problem of land mines in war-torn countries, could turn out to be very useful.

The American Physical Society Announces New, Open-Access Journal

With perhaps the coolest name for a journal yet, Physical Review X (PRX), a new open-access journal from the American Physical Society, will publish its first article in Fall of 2011. From the press release:

As broad in scope as physics itself, PRX will publish original, high quality, scientifically sound research that advances physics and will be of value to the global multidisciplinary readership. PRX will provide validation through prompt and rigorous peer review, and an open access venue in accord with the strong reputation of the Physical Review family of publications.

I love open access, mostly because its easy to get a hold of the articles you want to read. There are also far too few of them, but there has been some pushing to get more open-access journals out there.

So PRX will publish studies from all areas of physics. Me, with my mind in the gutter immediately thought that with a name like Physical Review X it would be about dirty things, but alas, it remains about reputable research.

Thats alright though, I can settle for regular physics research too. And also check out the editor of this journal, Jorge Pullin, Chair of the Horace C. Hearne, Jr. Institute for Theoretical Physics and professor in the Louisiana State University Center for Computation & Technology and Department of Physics and Astronomy.

Jorge Pullin, Editor of PRX. From the PRX homepage

Possibly the best chops I’ve seen on a physicist; or on anyone for that matter. Awesome.

The Physics of Coffee Rings

In keeping with the abstract on the physics of jump rope, the 63rd meeting of the American Physical Society has yielded yet another fascinating study.

63rd Annual Meeting of the APS Division of Fluid Dynamics

Volume 55, Number 16 

Abstract: RU.00007 : Coffee ring deposition in bands

Authors:

  Shreyas Mandre
    (Brown University)

  Ning Wu
    (Colorado School of Mines)

  Joanna Aizenberg
    (Harvard University)

  Lakshminarayanan Mahadevan
    (Harvard University)

Microscopic particles suspended in a liquid are transported and deposited at a contact line, as the contact line recedes due to evaporation. A particle layer of uniform thickness is deposited if the particle concentration is above a threshold; below this threshold the deposit forms periodic bands oriented parallel to the contact line. We present a model for the formation of these bands based on evaporation leading to the breakup of the thin liquid film near the contact line. The threshold results from a competition between evaporation speed and deposition speed. Using this model, we predict the thickness and length of the bands, making the control of patterned deposition possible.

[My comments: The authors used glass particles in a liquid to mathematically model how rings form. They can make these predictions using parameters such as evaporation rate and surface tension of the liquid. Aside from just being interesting, this study may have some practical implications for working at small scales.

“Controlling the ring deposition process would be useful for creating such things as new microphysics tools operating at a scale where pliers or other traditional tools for moving particles cannot operate,” notes Mandre. (From Physorg.com)]

The Physics of Jumping Rope

63rd Annual Meeting of the APS Division of Fluid Dynamics Volume 55, Number 16 

Abstract: CX.00008 : The aerodynamics of jumping rope

Authors:

  Jeffrey Aristoff
    (Department of Mechanical and Aerospace Engineering, Princeton University)

  Howard Stone
    (Department of Mechanical and Aerospace Engineering, Princeton University)

We present the results of a combined theoretical and experimental investigation of the motion of a rotating string that is held at both ends (i.e. a jump rope). In particular, we determine how the surrounding fluid affects the shape of the string at high Reynolds numbers. We derive a pair of coupled non-linear differential equations that describe the shape, the numerical solution of which compares well with asymptotic approximations and experiments. Implications for successful skipping will be discussed, and a demonstration is possible.

[My comments: The authors built a robot jump rope device and controlled parameters of rope rotation rate, rope density, diameter, length etc. using high speed cameras, they developed equations to describe the motion of the jump rope.

“Our main discovery is how the air-induced drag affects the shape of the rope and the work necessary to rotate it,” says Princeton researcher Jeff Aristoff. “Aerodynamic forces cause the rope to bend in such a way that the total drag is reduced.” (Leaves do this too when they bend out of the wind.) This deflection or twisting is most important in the middle of the rope and the least at the ends. If the rope is too light it might not clear the body of the jumper. (From Physorg.com)

I hope they did a demonstration. My experience is that physics conferences can be a bit stuffy.]