Earthquake prediction using electric fields

Wouldn't it be great if we could predict earthquakes (not quite as good as preventing though)? Some researchers have found evidence that electric fields in the vicinity can be used to predict major earthquakes. I think it has managed to predict most major earthquakes in Greece but it has missed some as well. Phys. Rev. Lett. 2003, 91, 148501.

Magnetic Refrigeration

Chemicals used in conventional refrigeration systems are polluting the environment. Magnetic refrigeration is a new way to cool things. They did not usually work at room temperature but the following is promising. Nature, 2001, 415, 150. Chubu Electric Power appears to be getting close to a product. http://www.chuden.co.jp/english/corporate/press2006/1107_1.html

Quantum mechanics imrpoves car efficiency

Abstract from Phys. Rev. Lett., 88, 050602, 2002. By using a laser and maser in tandem, it is possible to obtain laser action in the hot exhaust gases of a heat engine. Such a “quantum afterburner” involves the internal quantum states of the working molecules as well as the techniques of cavity quantum electrodynamics and is therefore in the domain of quantum thermodynamics. It is shown that Otto cycle engine performance can be improved beyond that of the “ideal” Otto heat engine. Furthermore, the present work demonstrates a new kind of lasing without initial inversion.

Protein folding shapes

In Phys. Rev. Lett. 87, 198103, 2001, they discovered an upper limit on the number of shapes that a protein can fold into. This sort of result should be useful for the pharmaceutical industry since a lot of their products are proteins.

Solar cell efficiency

Efficiency of solar cells could rise after the discovery of indium nitride having only 0.7eV band gap instead of 2.0eV. See Phys. Rev. B, 66, 201403, 2002. As of 2002, the efficiency of solar cells were 35% compared to the theoretical limit of 70%. By having a smaller band gap, it can absorb the light which is less energetic. By stacking various different band gap materials, the solar cell can absorb a greater range of energetic light.

Pure carbon magnets

Magnets are usually metallic. T. Makarova et al. 2001, Nature, 413, 716 report that pure carbon can be magnetic at room temperature. This may mean cheaper and lighter magnets.

Tuning lasers with rubber

Rubber can be used to tune a laser so you can obtain many different wavelengths. This can be used to simplify optical networks.

Notable work on heat engines

This paper will be useful when building an efficient yet cheap heat engine. Heat engines are prevalent in all places where energy is converted from one form into another.

Nature 399, 335-338, 1999

A thermoacoustic Stirling heat engine

S. Backhaus and G. W. Swift

Abstract

Electrical and mechanical power, together with other forms of useful work, are generated worldwide at a rate of about 10¹² watts, mostly using heat engines. The efficiency of such engines is limited by the laws of thermodynamics and by practical considerations such as the cost of building and operating them. Engines with high efficiency help to conserve fossil fuels and other natural resources, reducing global-warming emissions and pollutants. In practice, the highest efficiencies are obtained only in the most expensive, sophisticated engines, such as the turbines in central utility electrical plants. Here we demonstrate an inexpensive thermoacoustic engine that employs the inherently efficient Stirling cycle. The design is based on a simple acoustic apparatus with no moving parts. Our first small laboratory prototype, constructed using inexpensive hardware (steel pipes), achieves an efficiency of 0.30, which exceeds the values of 0.10–0.25 attained in other heat engines with no moving parts. Moreover, the efficiency of our prototype is comparable to that of the common internal combustion engine (0.25–0.40) and piston-driven Stirling engines (0.20–0.38).

Fake or not art

How do you determine if art work is genuine or not? You may expect experts in the art world could tell the difference but there have been paintings sold for millions that were later deemed fake. Physics can actually come to the aid of art by telling if an art work is fake or not.

Lighting efficiency

Lighting efficiency for incandescent light bulbs are only around 2 to 3 percent. With fluorescent tubes, you may get around 15 percent. It would be interesting to find ways to improve on these figures. Just imagine the amount of energy we can save. The following may contain something relevant. René T. Wegh, Harry Donker, Koenraad D. Oskam and Andries Meijerink have written a paper in Science 1999, 283, 663 with the following abstract.

For mercury-free fluorescent lamps and plasma display panels, alternative luminescent materials are required for the efficient conversion of vacuum ultraviolet radiation to visible light. Quantum cutting involving the emission of two visible photons for each vacuum ultraviolet photon absorbed is demonstrated in Eu³⁺-doped LiGdF₄ with the concept of downconversion. Upon excitation of Gd³⁺ with a high-energy photon, two visible photons can be emitted by Eu³⁺ through an efficient two-step energy transfer from Gd³⁺ to Eu³⁺, with a quantum efficiency that approaches 200 percent.

Sizing and sorting DNA molecules

In 1998, Hou-Pu Chou, Charles Spence, Axel Scherer, and Stephen Quake found a way to size and sort DNA molecules. Their method is fast and requires few samples. This should be particularly useful in the medical industry. Proc. Nat. Acad. Sci. 1999, 96, 11

Stickiness theory

Researchers in Physical Review Letters, 1999, 82, 936 have shown that surface roughness on micron scales combined with air suction can be stickier than thermodynamic effects alone. This could be relevant in sports where stickiness is important. Well, stickiness is important in many other areas other than sport.

Nanotubes for sieving

Nanotubes can be used to separate atoms or molecules. The first simulations were in Physical Review Letters, 1999, 82, 956. One application is to separate hydrogen from the radioactive isotope tritium in water used to cool the nuclear fuel rods. There should be medical applications as well.

Re-reading Physics World magazine

I am re-reading the Physics World magazine from January 1999. It will be interesting to see how things have panned out.

No more cracks in paint using physics

The paint industry could be helped by some work done in (Phys. Rev. Lett. 98 218302). They have been investigating the factors involved in the cracking of paint as it dries.

Natural negative refractive index material

Title: Negative Refraction Observed in a Metallic Ferromagnet in the Gigahertz Frequency Range. Abstract: It is generally believed that nature does not provide materials with negative refraction. Here we demonstrate experimentally that such materials do exist at least at GHz frequencies: ferromagnetic metals reveal a negative refraction index close to the frequency of the ferromagnetic resonance. The experimental realization utilizes a colossal magnetoresistance manganite La_2/3Ca_1/3MnO₃ as an example. In this material the negative refractive index can be achieved even at room temperature using external magnetic fields. Phys. Rev. Lett. 98, 197401 (2007)

It is a surprise to find a naturally occurring negative refractive index material. If the material is not so scarce, it could be cheaper to use than fabricated materials. It is promising that it works at room temperature but I wonder how large the magnetic field has to be? The frequency range limit will restrict the uses. Negative refractive index materials can be used to construct superlenses that have a much higher resolution compared to the wavelength used. I can see this being useful in medical imaging devices and possibly photolithography to make ever smaller computer chips.

Better solar energy harnessing?

Harnessing solar energy is a great way to reduce our dependence on other forms of energy. But the current efficiencies and costs are not too attractive. Could mimicking the way the plants harness energy (photosynthesis) be the answer? Some new insights showing a connection with quantum behaviour have been discovered (Nature 446 782). I do hope this is a useful step in finding more efficient ways to harness solar energy and leading to more cost effective manufacture.

Predicting solar activity

Predicting solar activity can be useful when you consider the disruption it causes to the communication systems. More in (Phys. Rev. Lett. 98 131101).

Infrared light for non-invasive scan

The infrascanner by Infrascan Inc. is a very simple device that uses infrared light to scan a surface injury like brain hematomas. This will be useful for paramedics to ascertain the injury or at hospitals that cannot afford more accurate but expensive equipment.

Organic nanowire spin valves with long spin relaxation times

I have not had the time to look into this but it appears that these spin valves could be useful in a quantum computer. If the spin relaxation time of 1 second is equivalent to the coherence time, it is long enough for a decent number of quantum computations. (Nature Nanotechnology 2, 216)

Non-invasive surgery using MRI

Non-invasive surgery can be conducted using magnetic resonance imaging by controlling the movement of a metal bead within the body. (App. Phys. Lett. 90 114105). This is not really marketable but it is nice to see physics in action within the medical field.

Better earthquake understanding?

From PhysicsWeb article:

In 1926, Russian physicist Yakov Frenkel proposed a theory that put a limit on the amount of stress a perfect crystal can withstand before its structural planes begin to slip over one another. Now, however, physicists from Norway have made a theoretical model showing that before Frenkel's limit is ever reached, crystals will deform due to a process called "thermal runaway" -- whereby strain and heat amplify rapidly. This could shed light on the mechanisms underlying deep earthquakes, and could help engineers to determine material tolerances more accurately
(Phys. Rev. Lett. 98 095504).

Quantized magnetoresistance could improve magnetic data storage

A recent article in Nature Nanotechnology (2, 171) could pave the way for better magnetic data storage devices. I am not too sure how long magnetic data storage devices will exist in the future. If the cost of semiconductor memory comes down sufficiently, they may replace magnetic devices completely. The abstract reads:

When the dimensions of a metallic conductor are reduced so that they become comparable to the de Broglie wavelengths of the conduction electrons, the absence of scattering results in ballistic electron transport¹ and the conductance becomes quantized. In ferromagnetic metals, the spin angular momentum of the electrons results in spin-dependent conductance quantization and various unusual magnetoresistive phenomena. Theorists have predicted a related phenomenon known as ballistic anisotropic magnetoresistance (BAMR). Here we report the first experimental evidence for BAMR by observing a stepwise variation in the ballistic conductance of cobalt nanocontacts as the direction of an applied magnetic field is varied. Our results show that BAMR can be positive and negative, and exhibits symmetric and asymmetric angular dependences, consistent with theoretical predictions.

Microscope that determines and manipulates atoms

A new atomic force microscope can determine and manipulate atoms on a surface. This is quite an advanced step because when I used one about seven years ago, it could only detect the position of atoms so that you could see the surface texture. This should be useful in designing devices for nanotechnology but the costs I would think will be significant. (Nature 446 64).

Better electron focus with graphene

Interesting to know that graphene could be produced to have negative refractive index which can then be used to focus electrons better than existing technology (Science 315 5816 ). Improving the focus of electrons means that you can improve the image you are after. I wonder whether it can be used to improve the focus of other particles?

Predicting hurricane intensity

Predicting a hurricane is useful and there are existing computer models that do a pretty good job. But predicting the intensity of a hurricane has been difficult. There is a paper (Science 315 1235) that claims to help predict when the hurricane will intensify and how strongly it will intensify.

No universally strong knot?

A paper (New Journal of Physics 9 65) discusses about the strength of knots depends on the type of material of the knot. This appears to suggest that there may not be a strongest knot for every material. I suppose industries that make use of knots must take heed. For instance, fishing nets should use the strongest knot for a particular material (environmentally, it would be nice to have nets that will break and release something like a dolphin).

Lasers save energy

According to physicsweb.org, a laser called a polariton laser saves energy compared to the conventional solid state lasers. It only uses a tenth of the energy. This is a significant saving. The polariton lasers did not used to operate at room temperature but now they do. They could be ideal for optical data storage devices. For details (Phys. Rev. Lett. 98 126405)

Nanotubes versus copper

Can nanotubes replace the copper fins that are attached to silicon chips for cooling purposes? Researchers have found that the nanotubes dissipate heat at the same rate as copper. The advantage is that the nanotubes are 10 times lighter, stronger and more flexible. If the price is right, great but I have a feeling that the costs could be a real turn off. Besides, how much of the weight say in a portable gadget like a mobile phone is made up of copper fins? The weight saving may well be imperceptible. Here is the reference for those who are interested (Appl. Phys. Lett. 90 123105).