Magnetic scan without magnets

Magnetic scans with a tiny magnet, by Michael Schirber

discussion of the paper entitled Near-Zero-Field Nuclear Magnetic Resonance by M. P. Ledbetter, T. Theis, J. W. Blanchard, H. Ring, P. Ganssle, S. Appelt, B. Blümich, A. Pines, and D. Budker

Phys. Rev. Lett. 107, 107601 (Published September 1, 2011)
"Nuclear magnetic resonance is a powerful technique for analyzing molecular structure in biology, medicine, and materials science. Conventionally, it calls for huge magnets to align nuclear spins and to detect them with high sensitivity, but recent work has demonstrated that similar analysis can be done without a magnetic field. The problem with this zero-field technique is that it can’t unambiguously identify molecules. Now, in a paper in Physical Review Letters, Micah Ledbetter of the University of California, Berkeley, and his collaborators address this limitation, showing that a very small magnetic field can provide extra signatures for chemical discrimination."
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.107.107601

An acoustic superlens from a few cans of cola

""Acoustic metamaterial" may sound exotic, but researchers in France have managed to assemble one from a few multipacks of cola cans. Arranged in a grid, the drinks cans act as a superlens for sound, focusing acoustic waves into much smaller regions than their metre-long wavelengths typically allow. The cans act as resonators, directing the volume of the sound to peak in a space just a few centimetres wide, and this heightened precision could improve acoustic-actuator systems."

How to make a superlens from a few cans of cola - physicsworld.com

A "Mobius" graphene

"In 1858, August Mobius dreamt up a shape with a single surface and only one edge. The Mobius strip has fascinated children and scientists alike since then.
How small can these shapes be? In December 2003, German chemists made a molecular Mobius strip out of a benzene-like ring modified with a belt-like carbon structure. Since then, various groups have produced increasingly bizarre Mobius-type molecules, including one that can switch back and forth from a Mobius to an ordinary strip when zapped with light.
Of course, the obvious choice of material with which to make Mobius molecules is graphene. But this particular trick has eluded chemists, an omission that clearly irks. Now Douglas Galvao from the Universidade Estadual de Campinas in Sao Paolo, Brazil, and buddies have decided to grip the bull by the horns and calculated the properties that Mobius carbon might have."New form of "Mobius" carbon predicted - Technology Review

Efimov states

"Tractable three-body problems are rare, which is why Vitaly Efimov’s study in 1970 proposing that bound states could exist between three interacting bosons was so intriguing. It took more than3 0 years, though, to observe Efimov states in an ultracold gas of cesium atoms, in which interactions could be controlled with a magnetic field. Now, writing in Physical Review Letters, theorists suggest similar states should also exist between dipolar molecules."

http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.106.233201

To use sound waves to measure temperature

"A sensor that uses sound waves to measure temperature could replace thermometers that lose accuracy in harsh environments such as nuclear power stations. Scientists at UK measurement institute the National Physical Laboratory (NPL) are using the long-established principle that sound travels faster through warm air to create a cheap and robust thermometer that doesn’t need recalibrating or replacing. They hope the device would be used to measure extremely high temperatures or in locations where it would be difficult to change the thermometer, such as in nuclear reactors."

Sensor uses sound waves for temperature measurement | News | The Engineer

Photosynthesis and the entanglement

"Recent studies have indeed suggested that electronic excitation transfer (EET) in photosynthesis benefits from quantum entanglement. ... To model the photosynthesis that occurs in plants, Briggs and Eisfeld study a collection of monomers, each possessing a single electronic state and coupled to its neighboring units by a dipolar interaction. The authors find that for dipolar interactions similar to those found in real molecular aggregates, the coherences in quantum transport (from the Schrödinger equation) are identical to those occurring in classical transport according to Newton’s equation."

Photosynthesis disentangled?

Graphite oxides boost supercapacitors

"Researchers in the US have discovered a new form of carbon produced by "activating" expanded graphite oxide. The material is full of tiny nanometre-sized pores and contains highly curved atom-thick walls throughout its 3D structure. The team has also found that the material performs exceptionally well as an electrode material for supercapacitors, allowing such energy-storage devices to be used in a wider range of applications."

http://nanotechweb.org/cws/article/tech/45975

Boosting the thermoelectric performances

"Physicists in the US and China have boosted the performance of a common thermoelectric material by modifying its electronic band structure. The improvement was made by carefully adjusting the relative abundances of tellurium and selenium in a lead alloy. The result is a material with an all-time-high thermoelectric figure of merit of 1.8 – a result that could lead to new types of thermoelectric devices that can convert waste heat into useful electricity"

Multiple valleys boost thermoelectric performance - physicsworld.com

Noether's (first) theorem

"Noether's (first) theorem states that any differentiable symmetry of the action of a physical system has a corresponding conservation law. The theorem was proved by German mathematician Emmy Noether in 1915 and published in 1918.[1] The action of a physical system is the integral over time of a Lagrangian function (which may or may not be an integral over space of a Lagrangian density function), from which the system's behavior can be determined by the principle of least action.
Noether's theorem has become a fundamental tool of modern theoretical physics and the calculus of variations. A generalization of the seminal formulations on constants of motion in Lagrangian and Hamiltonian mechanics (1788 and 1833, respectively), it does not apply to systems that cannot be modeled with a Lagrangian; for example,dissipative systems with continuous symmetries need not have a corresponding conservation law." Wikipedia, l'enciclopedia libera.

Moth-Eye Structures for Broadband Antireflection

Appl. Phys. Express 3 (2010) 102602 (3 pages)  |Previous Article| |Next Article|  |Table of Contents|
|Full Text PDF: FREE (763K)|

Hybrid Moth-Eye Structures for Enhanced Broadband Antireflection Characteristics

Lanying Yang, Qin Feng, Binghao Ng, Xiangang Luo, and Minghui Hong

The authors are proposing hybrid moth-eye structures to have high antireflection propoerties. These structures can be applied to solar cells for high light -to-electricity cinversione efficiency

URL: http://apex.jsap.jp/link?APEX/3/102602/
DOI: 10.1143/APEX.3.102602

Elusive WIMPS

On the XENON collaboration to find WIMPS

WIMP no-show casts a shadow over dark matter - physicsworld.com

Neutrinos in IceCube

The IceCube Neutrino Observatory (or simply IceCube) is a neutrino telescope constructed at the Amundsen-Scott South Pole Station in Antarctica. Similar to its predecessor, the Antarctic Muon And Neutrino Detector Array (AMANDA), IceCube contains thousands of spherical optical sensors called Digital Optical Modules (DOMs), each with a photomultiplier tube (PMT) and a single board data acquisition computer which sends digital data to the counting house on the surface above the array. More http://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory
"IceCube, which was completed in December 2010, is a kilometer-cubed array of photodetectors that have been drilled down into the Antarctic ice cap... The IceCube team compared 13 months of their data (collected when the array was half finished) to observations of 117 Gamma-Ray Bursts measured independently over the same time period. Contrary to expectations, no high-energy neutrinos were detected within a half-hour of each GRB. Theorists may need to rethink their models of GRBs, as well as look for other possible sources for the highest energy cosmic rays." This is what Michael Schirber writes in
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.106.141101

Tevatron claims glimpse of particles beyond standard model

Tevatron claims possible glimpse of particles beyond the standard model - April 06, 2011
"Just as the Tevatron, the proton-antiproton collider at Fermilab in Batavia, Illinois, enters its final months of operations, possible signals of new physics are emerging. First came a report from the Collider Detector at Fermilab (CDF) experiment of a puzzling asymmetry in the way top quarks decay into lighter particles. Now the same experiment is reporting on the possible observation of particles beyond the standard model in collisions that produce a W boson – a particle of the weak nuclear force. Spokesmen for the experiment say the signal may be due to random fluctuations, but that it’s nonetheless causing some excitement. “Either what we thought we knew about this process is wrong or there’s a totally new effect,” says Giovanni Punzi, CDF co-spokesman."

More Nature.com

The hunt for the elusive Higgs

"Physicists at CERN's Large Hadron Collider (LHC) are confident that they can find the Higgs boson by the end of 2012, when the machine will be shut down temporarily...The most sought after particle in particle physics – the Higgs boson – is believed to endow all other particles with mass. It is also the last undiscovered component of particle physicists' great theoretical framework – the Standard Model. After decades searching for the Higgs in particle collisions at CERN, and at Fermilab in the US, researchers at the LHC believe they may finally have the elusive particle within their grasp."

The hunt for the elusive Higgs - physicsworld.com

Thin film has 'astonishing' ability to rotate light

"Physicists in Austria and Germany have taken the Faraday effect to a new extreme by rotating the polarization of light by 45° by passing it through an extremely thin film. This "giant Faraday effect" could someday be used to create optical transistors that switch light or to improve terahertz imaging systems."
Thin film has 'astonishing' ability to rotate light - physicsworld.com

Superconductivity from nowhere

"In just over a week scientists will celebrate the centenary of superconductivity: the discovery, in 1911, that some materials cooled towards absolute zero allow electric charge to flow without resistance. But now one physicist believes superconductivity can appear when there is no material at all. According to Maxim Chernodub ... superconductivity can appear – provided there is a very strong magnetic field – in the vacuum of empty space. If Chernodub is correct, the phenomenon could explain the origin of the extensive magnetic-field patterns seen in the cosmos."

Superconductivity from nowhere - physicsworld.com

Revelations of a golden age

"For roughly 700 years, many of the greatest scientists lived in the Islamic world. The Western narrative, however, has often neglected the contributions of major figures such as the chemist al-Jabir, the mathematician al-Khwarizmi and the medic al-Razi, preferring instead to jump directly from Aristotle, Euclid, Archimedes and Ptolemy to Copernicus and Galileo in reporting scientific development over the ages. Yet the fact is that between the eighth and 15th centuries AD, the scientists of the Islamic world developed original theories in mathematics, astronomy, physics, medicine and engineering – frequently with the help of works translated into Arabic from Greek, Sanskrit, Pahlavi and Syriac sources." by George Gheverghese Joseph, Revelations of a golden age - physicsworld.com
On the book "Pathfinders: The Golden Age of Arabic Science",  by Jim Al-Khalili

Folding furrows

Folds on the surface of soft materials are shown to be a consequence of a nonlinear instability.

"Even as we probe physics on ever-smaller scales, materials that can be held and manipulated with our hands often still resist our understanding. Elastic materials, in particular, still confound because of the nonlinear relationship between strain and the displacement of the material needed to maintain the rotational invariance of the elastic energy. The effects of these nonlinearities are often more pronounced at free surfaces, where strain can be alleviated by a large rotation of the surface. When a slab of an elastic material such as rubber is compressed, it develops a sulcus—a sharp furrow in its surface that plunges into the material. First reported for photographic gelatin films over one hundred years ago, they are not just a laboratory curiosity. Sulci create large strains that can lead to material failure. They are also a common motif in the morphogenesis of many organs, most famously in the characteristic folds on the surface of the human brain or, say, the arm of an infant ..."
Physics - Folding furrows, Physics 4, 19 (2011), DOI: 10.1103/Physics.4.19, Folding furrows, Christian D. Santangelo, a viewpoint on: Unfolding the Sulcus, by Evan Hohlfeld and L. Mahadevan, Phys. Rev. Lett. 106, 105702 (2011) – Published March 07, 2011, Download PDF

Surface boosts conductivity of nanocrystals

Surface states boost conductivity of Ge nanocrystals
"Ge nanocrystals are promising materials for developing nanoscale optoelectronic devices, such as band-gap engineered tandem solar cells, thanks to low processing temperatures and full compatibility with large-scale integrated circuit fabrication. Many groups have successfully developed technologies to synthesize Ge nanocrystals embedded in SiO2 thin films and to control the structural and optical properties of the nanocomposite. Nevertheless, implementation in practical devices has rarely been demonstrated. This can be partially attributed to the difficulty in making electrically conductive thin films."

http://nanotechweb.org/cws/article/lab/45268

Acoustics of free-reed instruments

Documents dating back to before 1000 BC describe a wind instrument whose reed vibrates back and forth across the frame that houses it. Nowadays, free-reed instruments inspire both scholarly study and musical innovation. James Cottingham , Acoustic of free-reed instruments, Physics Today, March 2011, Vol.63, pp. 44-48.
A free reed? What is it? More http://www.patmissin.com/history/whatis.html