Shma Shot about Physics

Studies on zinc oxide nanobelts hint at a simple strategy for diagnosing and repairing structural faults in nanodevices. Damaged nanobelts show a surprising capacity to ‘self-heal’ when an electric present is applied, the researchers report.

Any device, throughout its lifetime, will inevitably endure some mechanical damage. If the damage may be detected, it could be probable to repair it, or if not the device will most likely be thrown away. In the nano-realm, nonetheless, monitoring for harm has proved particularly tricky. But Xiaodong Li at the University of South Carolina in Columbia, US and colleagues may possibly have discovered a answer.

They focused on zinc oxide nanobelts – flat structures that will carry an electric present – simply because they have a potentially wide range of applications and have been utilised in producing piezoelectric devices and nanogenerators. To realize how the structures responded to structural harm they dented them using the tip of an atomic force microscope, observing dramatic drops in electrical conductivity as a result. This initial observation is, in itself, considerable, given that it suggests that damage to device components might be diagnosed by monitoring of an electrical signal.

What happened subsequent, nevertheless, was even more intriguing. Right after an electric present was applied, the nanobelts regained considerably of their former function – they ‘self-healed’ – with healing time depending on the force applied. ‘You may say this nanodevice is damaged and throw it away, but after you give the current for a few minutes you might totally recover this nanodevice,’ says Li. He explains that local heating of the material when the electric current is applied helps to anneal dislocations within the materials.

The self-healing procedure is ‘rather unexpected’, according to Duncan Gregory, a nanomaterials expert at the University of Glasgow, UK. ‘The mechanisms for these processes are not yet recognized and there is lots of scope for additional investigations of the origins of these effects along with the thermodynamics involved,’ he says.

There’s a additional implication of the team’s findings though – that by creating precise indents in supplies like nanobelts, it could possibly be feasible to tune their electrical properties. ‘A lot of men and women in market ask me, “Well, if I’ve a nanowire, can I tune or modify its electrical signal?”,’ says Li. ‘So here is often a straightforward methodology.’ His team is already attempting to extend its work into other materials inside the hope that it’ll lead to new guidelines for nanodevice design and manufacture.

Researchers have incorporated a sunlight-activated trigger into an oxygenation procedure that uses water as the oxygen source. The combination strategy is really a step towards mimicking nature’s photocatalytic processes and could support lessen carbon dioxide emissions and lead to additional applications for solar power.

Shunichi Fukuzumi and coworkers from Osaka University in Japan and Wonwoo Nam from Ewha Womans University in Seoul, Korea and colleagues have developed highly efficient photocatalytic oxygenations of organic substrates including sodium p-styrene sulfonate, utilizing sunlight as an initiator and water as an oxygen source.

The team employed a ruthenium (II) complicated that absorbs light and uses the power to lessen a cobalt complicated. The ruthenium (III) complex then goes on to react having a manganese porphyrin oxygenation catalyst. This reaction causes the manganese porphyrin complicated to give off a proton, and grow to be the active species responsible for the oxidation of organic substrates. The catalyst can oxygenate substrates by making use of water in a phosphate buffer remedy (pH 7.4) as an oxygen source.

‘This is an important step for the common use of water as a clean and abundant reactant making use of solar power,’ say Fukuzumi. He goes onto clarify that present industrial oxygenation processes are energy consuming, resulting in big amounts of CO2 emissions. ‘Oxygenation reactions using water as an oxygen source under mild conditions utilizing solar power would contribute to cut down CO2 emissions,’ he adds.

Richard Douthwaite, an expert in photocatalysis from the University of York in the UK, believes that the work is an intriguing proof of principle. ‘What they appear to have done is take two known reactions and stitch them together,’ he says. ‘But no-one has shown before that light may be employed to mediate these oxidation processes with water,’ he adds.

Fukuzumi acknowledges that there’s still work to complete to make the procedure truly environmentally benign. The team’s aim is to replace the cobalt complicated with molecular oxygen ‘to develop oxygenation reactions with water as the oxygen source, oxygen as the oxidant, beneath mild conditions making use of solar power.’

Swiss and Chinese scientists have created a new way of producing the porous TiO2 electrode for solid state dye-sensitised solar cells (ss-DSSCs). The approach may very well be more compatible with large scale manufacturing processes.

The team from the Federal Polytechnic School in Lausanne and also the Changchun Institute of Applied Chemistry were attempting to come up with an option to the titanium dioxide nanoparticle paste that has been utilized to create electrodes for DSSCs in a variety of types because their discovery by Michael Gr?tzel and Brian O’Regan in 1991.

You can find a number of issuesPlanet in the course of the recent Supplies Research Society meeting in Boston, US. ‘They are fairly poor electron conductors,’ he says, ‘which isn’t such a dilemma in cells with liquid electrolytes.’ But due to the fact these liquids tend to leak more than time and are much less suitable for mass production, there has been a move towards solid ‘hole transport material’ replacements.

Nonetheless, this throws up difficulties of its own. Because electrons are not transported through the structure rapidly enough, they tend to recombine with positively charged ‘holes’ inside the hole transport material rather than making their way out of the electrode to create an electrical present. ‘So we have to speed up the electrons inside theTo complete this the team created a brand new approach making use of rod-shaped particles, which self assemble and join together into nanowires in 15 seconds from aqueous answer. ‘We observed that when the nanorods fuse together their crystal structures are aligned which helps quicklyenhancing charge transport really should help increase the performance of the cells.
‘Not having to burn out a polymer binder [as is needed for the nanoparticle paste] opens up several far more possibilities in processing,’ Snaith adds. Nonetheless, he points out that the strategy still requires heating and treatment with titanium tetrachloride – inside the same way the nanoparticle structures would – to obtain very good conductivity betweencan be a drawback, but hints that the team is operating on a method to remove the heating step, which would open up the approach to polymer backing supplies to make flexible ss-DSSCs.

Snaith notes that the nanowire structure is a lot more porous than the particle-based electrodes, which should make it less complicated for the hole transport supplies to penetrate and fill the pores efficiently. Greater pore filling means the light-harvesting dye on the electrode surface shouldn’t degrade so easily. Nonetheless, he points out that to get a considerable boost in energy generation from ss-DSSCs will possibly require a mixture of a lot more radical modifications to the cell design.

Achieving such high spatial resolution has traditionally essential large, powerful electron microscopes operating at high accelerating voltages that blast atoms and can destroy specimens. But Suenaga and Koshino’s low voltage (60kV) set-up creates the needed brief wavelength electrons for high resolution spectroscopy, whilst leaving samples intact.

Though there have been previous reports of identifying components from a single atom utilizing similar approaches, this will be the 1st time certain spectral peaks have been obtained from particular atoms, according to Stephen Pennycook, a Stem specialist at Oak Ridge National Laboratory, Tennessee, US. ‘It’s nearly like seeing bonds 1 by one,’ he says.

The achievements are impressive, says Pratibha Gai, chair of electron microscopy at the University of York’s Jeol Nanocentre inside the UK. ‘The ability to record the reported data is often a remarkable feat given the instabilities and inevitably extremely weak signal,’ she adds.

Gai thinks the approach must be applicable to other nanomaterials. And as Suenaga points out, exploring the atomic level structures of nanodevices will become increasingly crucial. But for now, he has other plans for the method – for instance, in identifying the active atoms in individual molecules so that you can predict how chemical reactions will occur. Previously this has only been achievable by way of theoretical calculations, which would take too extended in massive molecules like proteins. Another thought is to use the technique to comprehend why, in solar cells, some silicon atoms perform much less well than other people.

A brand new, low voltage electron microscopy strategy makes it possible for scientists to discriminate not just between atoms of distinct components but between atoms of the very same element in diverse electronic states. The researchers who created it say it could be broadly applied to analyse the fine structures of nanomaterials and important biological molecules.

Kazu Suenaga and Masanori Koshino at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, utilized a low voltage, scanning transmission electron microscope (Stem) to probe carbon atoms in graphene. By measuring the power lost when electrons hit individual atoms, they had been in a position to tell a carbon atom with 1 bond from others with two or 3.
The team employed a probe just 0.1nm in diameter to zone in on single atoms. ‘In the past, if you had been making use of some other strategy, you can do spectroscopy for a local region of 1,000 atoms or a million atoms, a thing like that,’ explains Suenaga. ‘Now, having a extremely tiny probe, we can measure from single atoms.’

5 of the top eight physics and astrophysics articles most cited in 2004 had been authored by researchers from The Johns Hopkins University’s Henry A. Rowland Department of Physics and Astronomy, based on the SPIRES database of Stanford University.

Of the cited articles by Johns Hopkins faculty, Charles L. Bennett’s papers ?a which pinpointed the age of the universe ?a ranked initial and second, and those of Raman Sundrum, a physicist whose work opened new dimensions in space and time, ranked third and sixth. An article by astrophysicist Adam Riess ranked eighth. Riess and collaborators discovered the mysterious dark energy that’s pushing the universe apart.

“These rankings are a testament to the influence and reach of the physics and astronomy faculty here at Johns Hopkins,” mentioned Jonathan Bagger, chairman of the department within the Krieger School of Arts and Sciences.

Bennett came to Johns Hopkins on Jan. 1, 2005, from his previous position as a senior scientist for experimental cosmology at NASA’s Goddard Space Flight Center, and Sundrum arrived inside the summer time of 2000 from a postdoctoral position at Stanford University. Riess is an adjunct professor at Johns Hopkins University who will join the faculty full-time on Jan. 1 from his present position at the Space Telescope Science Institute on the Johns Hopkins Homewood campus.

The SPIRES database provides researchers worldwide a compendium of papers on physics and astrophysics, and tracks citations.

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Interestingly, the physics behind each inventions may be understood on the same principle, namely utilizing the wave nature of light, which involves encoding the image field by interference, recording the structure in a photographic plate, after which reading out the image field once again by sending light and getting it modulated in this structure.

Wave phenomena seem everywhere in physics. Most clearly, we see them on a water surface. We may observe that waves spread out with a propagation path, a propagation velocity or speed, and a length of their period.

When two or much more waves are superimposed, we notice that this outcomes in a pattern which is referred to as “interference.” Such an interference structure contains info on all the fields interacting. When 1 field is identified, information on the other fields can be also deduced.

Among the Nobel Prizes in Physics, two scientists have been honored for their remarkable methods to record and present pictures: Gabriel Lippmann, awarded in 1908 “for his method of reproducing colours photographically based on the phenomenon of interference,” and Dennis Gabor, awarded in 1971, “for his invention and development of the holographic method.”

Each methods had the identical aim of carrying image reproduction additional in a way that was fairly diverse from other earlier attempts produced for the same objective. To achieve this, Lippmann and Gabor chose a revolutionary method to basic physics instead of following an evolutionary progress in engineering.

In 1886, when the art and technology of photography was still struggling to transfer the colors of nature to adequate tonal values in black and white, Gabriel Lippmann conceived a two-step method to record and reproduce color images directly via the wavelengths in the object along with the subsequent photograph.

While Lippmann improved photography from black and white to color, Gabor’s holography extended photography from flat pictures to a three-dimensional image space. Procedures to offer to every single eye of the viewer its own parallax ?¡ìC stereoscopy ?¡ìC are as historical as photography itself. But Gabor’s idea of a “hologram” was to store all the info in all image space and not just in one slightly different second photograph.

Molecules are composed of atoms. They form the next degree of complexity when considered as many-body systems. But molecular phenomena have traditionally been viewed as a branch of chemistry (as exemplified by the Chemistry Prize in 1936 to Petrus J.W. Debye), and have only hardly ever been inside the focus for Nobel Prizes in Physics. A single exception is the recognition of the work by Johannes Diderik van der Waals, who formulated an equation of state for molecules in a gas taking into account the mutual interaction between the molecules together with the reduction of the totally free volume due to their finite size. van der Waals’ equation has been an important starting point for the description of the condensation of gases into liquids. He received the 1910 Physics Prize. Jean B. Perrin studied the motion of modest particles suspended in water and received the 1926 Physics Prize. His studies allowed a confirmation of Einstein’s statistical theory of Brownian motion in addition to of the laws governing the equilibrium of suspended particles below the influence of gravity.