Phase change materials that change their optical properties depending on the arrangement of the atoms allow for the storage of several bits in a single cell.
novel materials that change their optical properties depending on the arrangement of the atoms: Within shortest periods of time, they can change between crystalline (regular) and amorphous (irregular) states.
and some of those photons interfere with one another and find their way onto a detector,
a computer then reconstructs the path those photons must have taken, which generates an image of the target material--all without the lens that's required in conventional microscopy."
"Without a lens, the quality of the images primarily depends on the radiation source. Traditionally, researchers use big, powerful X-ray beams like the one at the SLAC National Accelerator Laboratory in Menlo Park, California, USA.
Over the last ten years, researchers have developed smaller, cheaper machines that pump out coherent, laser-like beams in the laboratory setting.
The table-top machines are unable to produce as many photons as the big expensive ones
hardly any photons will bounce off the target at large enough angles to reach the detector.
Without enough photons, the image quality is reduced. Zürch and a team of researchers from Jena University used a special, custom-built ultrafast laser that fires extreme ultraviolet photons a hundred times faster than conventional table-top machines.
With more photons, at a wavelength of 33 nanometers, the researchers were able to make an image with a resolution of 26 nanometers--almost the theoretical limit."
"Nobody has achieved such a high resolution with respect to the wavelength in the extreme ultraviolet before, "Zürch said.
Adsorption of molecules from solution onto a sensing surface alters the refractive index of the medium near this surface and,
These results mean, that the new chip needs much less molecules for detecting a compound
and can be used for analysis of chemical reactions with small drug molecules. An important advantage of the new GO based sensor chips is their simplicity
i e. depending on the arrangement of the atoms in the material. This changeability between crystalline (regular) and amorphous (irregular) states allowed the team to store many bits in a single integrated nanoscale optical phase-change cell l
They can also be filled with a wide variety of biomolecules. ne can imagine filling the capsules with molecules such as medications
noninvasive 3d biomedical imaging photonic chips aerospace photonics micromachines laser tweezing the process of using lasers to trap tiny particles.
inexpensive tests using DNA Chemists at the University of Montreal used DNA molecules to developed rapid,
when atoms are brought too close together-to detect a wide array of protein markers that are linked to various diseases.
nanometer particles with the ability to absorb light and re-emit it with well-defined colors.
where the particle size determines the color of the emitted light. The new strategy relies on a completely different physical mechanism;
The researchers designed a new type of nanocarrier based on the biocompatible molecule poly (ethylene glycol or PEG, that releases its cargo only in targeted immune cells.
#Ultrafast lasers offer 3-D micropatterning of biocompatible hydrogels Tufts University biomedical engineers are using low energy,
Further, the exceptional clarity of the transparent silk gels enabled the laser's photons to be absorbed nearly 1 cm below the surface of the gel-more than 10 times deeper than with other materials
The system uses direct optical detection of viral molecules and can be integrated into a simple, portable instrument for use in field situations where rapid,
Because PCR works on DNA molecules and Ebola is an RNA VIRUS, the reverse transcriptase enzyme is used to make DNA copies of the VIRAL RNA prior to PCR amplification and detection."
For over a decade, Schmidt and his collaborators have been developing optofluidic chip technology for optical analysis of single molecules as they pass through a tiny fluid-filled channel on the chip.
The targeted molecules--in this case, Ebola virus RNA--are isolated by binding to a matching sequence of synthetic DNA (called an oligonucleotide) attached to magnetic microbeads.
A collaboration between researchers at the University of Gothenburg and the University of Iceland has been to study a new type of nuclear fusion process.
This produces almost no neutrons but instead fast, heavy electrons (muons), since it is based on nuclear reactions in ultra-dense heavy hydrogen (deuterium)."
"This is a considerable advantage compared to other nuclear fusion processes which are under development at other research facilities,
since the neutrons produced by such processes can cause dangerous flash burns, "says Leif Holmlid, Professor Emeritus at the University of Gothenburg.
No radiation The new fusion process can take place in relatively small laser-fired fusion reactors fuelled by heavy hydrogen (deuterium.
"A considerable advantage of the fast heavy electrons produced by the new process is that these are charged
The energy in the neutrons which accumulate in large quantities in other types of nuclear fusion is difficult to handle
because the neutrons are charged not. These neutrons are high-energy and very damaging to living organisms,
whereas the fast, heavy electrons are considerably less dangerous.""Neutrons are difficult to slow down or stop and require reactor enclosures that are several metres thick.
Muons-fast, heavy electrons-decay very quickly into ordinary electrons and similar particles. Research shows that far smaller and simpler fusion reactors can be built.
The next step is to create a generator that produces instant electrical energy y
#A new single-molecule tool to observe enzymes at work A team of scientists at the University of Washington
and the biotechnology company Illumina have created an innovative tool to directly detect the delicate, single-molecule interactions between DNA and enzymatic proteins.
Their approach provides a new platform to view and record these nanoscale interactions in real time. As they report Sept. 28 in Nature Biotechnology("Subangstrom single-molecule measurements of motor proteins using a nanopore),
"this tool should provide fast and reliable characterization of the different mechanisms cellular proteins use to bind to DNA strands information that could shed new light on the atomic-scale interactions within our cells
and help design new drug therapies against pathogens by targeting enzymes that interact with DNA"There are other single-molecule tools around,
but our new tool is said far more sensitive senior author and UW physics professor Jens Gundlach."
they developed this tool the single-molecule picometer-resolution nanopore tweezers, or SPRNT while working on a related project.
Our genes are long stretches of DNA molecules, which are made up of combinations of four chemical DNA"letters."
"Generally, most existing techniques to look at single-molecule movements such as optical tweezers have a resolution, at best,
When the active ingredients of sunscreen absorb UV LIGHT a chemical change triggers the generation of oxygen-carrying molecules known as reactive oxygen species (ROS.
The nanoparticle hydrophilic layer essentially locks in the active ingredient, a hydrophobic chemical called padimate O. Some sunscreen solutions that use larger particles of inorganic compounds, such as titanium dioxide or zinc oxide,
but if operated in countries with high solar irradiance it would be possible to generate solar electricity at low cost owing to the high energy conversion efficiency.
This results in more accurate measurements of molecules in diseased tissue and improved quantitative imaging capabilities."
"In this work, we have made two major advances--the ability to precisely control the brightness of light-emitting particles called quantum dots,
an assistant professor of bioengineering at Illinois."Previously light emission had an unknown correspondence with molecule number.
and calibrated to accurately count specific molecules. This will be particularly useful for understanding complex processes in neurons
""Fluorescent dyes have been used to label molecules in cells and tissues for nearly a century, and have molded our understanding of cellular structures and protein function.
These attributes obscure correlations between measured light intensity and concentrations of molecules,"stated Sung Jun Lim, a postdoctoral fellow and first author of the paper"
and tunable number of photons per tagged biomolecule. They are expected also to be used for precise color matching in light-emitting devices and displays,
and for photon-on-demand encryption applications. The same principles should be applicable across a wide range of semiconducting materials."
#Physicists succeed in direct detection of vacuum fluctuations What are the properties of the vacuum, the absolute nothingness?
They demonstrated a first direct observation of the so-called vacuum fluctuations by using short light pulses while employing highly precise optical measurement techniques.
According to quantum physics, these oscillations exist even in total darkness when the intensity of light and radio waves completely disappears.
These findings are of fundamental importance for the development of quantum physics and will be published in the prestigious journal Science;
2015 The existence of vacuum fluctuations is known already from theory as it follows from Heisenberg uncertainty principle, one of the main pillars of quantum physics.
Instead, it is assumed usually that vacuum fluctuations are manifested in nature only indirectly. From spontaneous emission of light by excited atoms e g. in a fluorescent tube to influences on the structure of the universe during the Big Bang:
these are just some of the instances that highlight the ubiquitous role the concept of vacuum fluctuations plays in the modern physical description of the world.
An experimental setup to measure electric fields with extremely high temporal resolution and sensitivity has made now it possible to directly detect vacuum fluctuations,
despite all contrary assumptions. World-leading optical technologies and ultrashort pulsed laser systems of extreme stability provide the know-how necessary for this study.
The research team at the University of Konstanz developed these technologies in-house and also an exact description of the results based on quantum field theory.
The sensitivity is limited only by the principles of quantum physics.""This extreme precision has enabled us to see for the first time that we are surrounded continuously by the fields of electromagnetic vacuum fluctuations"sums up Alfred Leitenstorfer."
"What is scientifically surprising and especially intriguing in our measurements is that we gain direct access to the ground state of a quantum system without changing it,
for example by amplification to a finite intensity"explains Leitenstorfer. He was stunned by the research results himself:"
The scientists developed a nanoscale photodetector that uses the common material molybdenum disulfide to detect optical plasmons--travelling oscillations of electrons below the diffraction limit
rather than solely to the laser's wavelength, demonstrating that the plasmons effectively nudged the electrons in Mos2 into a different energy state."
and deposited metal contacts onto that same end with electron beam lithography. They then connected the device to equipment to control its bias,
the energy was converted into plasmons, a form of electromagnetic wave that travels through oscillations in electron density.
This energy electronically excited an electron once it reached the molybdenum disulfide-covered end effectively generating a current.
Düsseldorf, Mainz, Princeton and Santa barbara, a ring of colloidal particles are localised in optical tweezers and automatically translated on a circular path,
Through optical manipulation the particle ring can be squeezed at will, altering the coupling between the driven and loaded parts of the assembly and providing a clutch-like operation mode."
which harness the science of the very small-the strange behaviour of subatomic particles-to solve computing challenges that are beyond the reach of even today's fastest supercomputers.
"We've morphed those silicon transistors into quantum bits by ensuring that each has only one electron associated with it.
We then store the binary code of 0 or 1 on the'spin'of the electron,
which is associated with the electron's tiny magnetic field, "he added. Dzurak noted that that the team had patented recently a design for a full-scale quantum computer chip that would allow for millions of our qubits,
or ion channels, each of which is a portal for specific ions. Ion channels are typically about 1 nanometer wide;
by maintaining the right balance of ions, they keep cells healthy and stable. Now researchers at MIT have created tiny pores in single sheets of graphene that have an array of preferences and characteristics similar to those of ion channels in living cells.
which scientists have studied ever ion flow. Each is also uniquely selective, preferring to transport certain ions over others through the graphene layer. hat we see is that there is a lot of diversity in the transport properties of these pores,
which means there is a lot of potential to tailor these pores to different applications or selectivities, says Rohit Karnik, an associate professor of mechanical engineering at MIT.
detecting ions of mercury, potassium, or fluoride in solution. Such ion-selective membranes may also be useful in mining:
In the future, it may be possible to make graphene nanopores capable of sifting out trace amounts of gold ions from other metal ions, like silver and aluminum.
Karnik and former graduate student Tarun Jain, along with Benjamin Rasera, Ricardo Guerrero, Michael Boutilier, and Sean Oern from MIT and Juan-carlos Idrobo from Oak ridge National Laboratory, publish their results today in the journal Nature Nanotechnology("Heterogeneous sub-continuum ionic transport in statistically isolated graphene nanopores").
which are slightly smaller than the ions that flow through them. hen nanopores get smaller than the hydrated size of the ion,
In particular, hydrated ions, or ions in solution, are surrounded by a shell of water molecules that stick to the ion,
depending on its electrical charge. Whether a hydrated ion can squeeze through a given ion channel depends on that channel size and configuration at the atomic scale.
Karnik reasoned that graphene would be a suitable material in which to create artificial ion channels:
A sheet of graphene is an ultrathin lattice of carbon atoms that is one atom thick, so pores in graphene are defined at the atomic scale.
The researchers then isolated individual pores by placing each graphene sheet over a layer of silicon nitride that had been punctured by an ion beam
The group reasoned that any ions flowing through the two-layer setup would have passed likely first through a single graphene pore,
The group measured flows of five different salt ions through several graphene sheet setups by applying a voltage and measuring the current flowing through the pores.
and from ion to ion, with some pores remaining stable, while others swung back and forth in conductance an indication that the pores were diverse in their preferences for allowing certain ions through. he picture that emerges is that each pore is different
and that the pores are dynamic, Karnik says. ach pore starts developing its own personality.
which given the single-atom thickness of graphene makes them among the smallest pores through
which scientists have studied ion flow. With the model, the group calculated the effect of various factors on pore behavior,
Knowing this, researchers may one day be able to tailor pores at the nanoscale to create ion-specific membranes for applications such as environmental sensing and trace metal mining. t kind of a new frontier in membrane technologies,
it is only through a fundamental understanding of ion transport that the overall anticipated behaviors of bulk graphene membranes can be drawn.
#Physicists turn toward heat to study electron spin The quest to control and understand the intrinsic spin of electrons to advance nanoscale electronics is hampered by how hard it is to measure tiny, fast magnetic devices.
Applied physicists at Cornell offer a solution: using heat, instead of light, to measure magnetic systems at short length and time scales.
if perfected, could lead to a novel tabletop magnetic measurement technique and new, nanoscale electronic devices based on electrical spin, rather than charge.
"Why the interest in electron spin? In physics, electron spin is established the well phenomenon of electrons behaving like a quantum version of a spinning top,
and the angular momentum of these little tops pointing por own. An emerging field called spintronics explores the idea of using electron spin to control
and store information using very low power. echnologies like nonvolatile magnetic memory could result with the broad understanding and application of electron spin.
Spintronics, the subject of the 2007 Nobel prize in Physics, is already impacting traditional electronics, which is based on the control of electron charge rather than spin. irect imaging is really hard to do,
Fuchs said. evices are tiny, and moving really fast, at gigahertz frequencies. Wee talking about nanometers and picoseconds.
In collaboration with theoretical physicists from the University of Kiel the researchers were able to identify the origin of the resistance change in the magnetic whirl:
it is due to the canting between the atomic magnets from one atom to the next (see figure.
The larger the angle between the adjacent atomic magnets, the stronger is the change in electrical resistance. lectrons have a spin,
When the electrons are travelling through a magnetic whirl, they feel the canting between the atomic magnets,
molecules can still move X-ray crystallography reveals the three-dimensional structure of a molecule, thus making it possible to understand how it works
That is why molecules consisting of the most compact crystals generally make it possible to obtain structures of better quality.
by showing that potassium can work with graphite in a potassium-ion battery-a discovery that could pose a challenge and sustainable alternative to the widely-used lithium-ion battery.
Lithium-ion batteries are ubiquitous in devices all over the world, ranging from cell phones to laptop computers and electric cars.
A potassium-ion battery has been shown to be possible. And the last time this possibility was explored was
"The Journal of the American Chemical Society published the findings from this discovery("Carbon Electrodes for K-Ion Batteries),
or high-energy reservoir of electrons. Lithium can do that, as the charge carrier whose ions migrate into the graphite
and create an electrical current. Aside from its ability to work well with a carbon anode
Right now, batteries based on this approach don't have performance that equals those of lithium-ion batteries,
"It's safe to say that the energy density of a potassium-ion battery may never exceed that of lithium-ion batteries,
Surrounding water molecules are red and white. The scientists discovered a design rule that enables a recently created material to exist.
It a flat structure only two molecules thick, and it composed of peptoids, which are synthetic polymers closely related to protein-forming peptides.
Surprisingly, these molecules link together in a counter-rotating pattern not seen in nature. This pattern allows the backbones to remain linear and untwisted,
the scientists set out to learn its atom-resolution structure. This involved feedback between experiment and theory.
when it comes to water and ions. These insights are intriguing on their own, but when the scientists examined the structure of the nanosheetsbackbone,
DNP-enhanced sensitivity Traditional NMR uses the magnetic properties of atomic nuclei to reveal the structures of the molecules containing those nuclei.
By using a strong magnetic field that interacts with the nuclear spins of carbon atoms in the proteins,
NMR measures a trait known as chemical shift for some of the individual atoms in the sample,
which can reveal how those atoms are connected. ou look at changes in chemical shift and that tells you, for example,
which requires transferring polarization from unpaired electrons to protons and then carbon nuclei, using microwaves generated by a gyrotron,
a high-frequency microwave oscillator developed in collaboration with Richard Temkin of MIT Department of physics and Plasma Science and Fusion Center.
the researchers label their target protein with carbon-13 a stable isotope of carbon while the rest of the proteins are unlabeled. his technique has the potential to really open up a wide range of studies,
the researchers found that their antenna retains all its essential properties such as gain, radiation pattern, directionality, operation frequency and bandwidth for up to 30%strain and for 2000 stretching cycles.
#New way to store information uses ions to save data and electrons to read data Scientists from Kiel University
and the Ruhr Universität Bochum (RUB) have developed a new way to store information that uses ions to save data
and electrons to read data. This could enable the size of storage cells to be reduced to atomic dimensions.
But that is not the only advantage of the new technology, as the researchers reported in the journal Scientific Reports("A double barrier memristive device").
Standard memory devices are based on electrons which are displaced by applying voltage. The development of ever smaller and more energy-efficient storage devices according to this principle,
It consists of two metallic electrodes that are separated by a so-called solid ion conductor usually a transition metal oxide.
as well as ions within the layer between being displaced. The advantage is that cells that are constructed in this way are easy to produce
and can be reduced to almost the size of atoms. The scientists achieve a long storage time by setting the ion density in the cells precisely via the voltage applied."
"That was a big challenge, "said Mirko Hansen, doctoral candidate and lead author of the study from Kohlstedt's team,
"Electrons are roughly 1000 times lighter than ions and so they move much more easily under the influence of an external voltage.
whereby in our component, the ions are immovable for extremely low voltages, while the electrons remain mobile
and can be used to read the storage status."The trick: the researchers built an ion conductor,
which was only a few nanometres (a millionth of a millimetre) thin to utilise quantum-mechanical effects for the flow through the storage cells."
"The tunnel effect enables us to move electrons through the ultra-thin layer with very little energy,
ions are moved within the storage cell at voltages above one volt, and electrons, on the other hand, at voltages far below one volt.
This way, ions can be used specifically for storing and electrons specifically for reading data. The researchers also reported that their research had another very interesting element.
The new resistance-based storage devices could even simulate brain structures. Rapid pattern recognition and a low energy consumption in connection with enormous parallel data processing would enable revolutionary computer architectures."
"This opens up a massive area for innovations in combination with terms like Industry 4. 0, in which autonomous robots work,
Graphene is an incredibly strong one-atom-thick layer of carbon, and is known for its excellent conductive properties of heat and electricity.
which involves the gaining of electrons. The reduced-graphene oxide-coated materials were found to be particularly sensitive to detecting nitrogen dioxide
Chemical reactions and material phase transitions, for example, happen on the scale of atoms --which are about one tenth of one billionth of a meter across--and attoseconds
Ultrafast electron pulses are one tool scientists use to probe the atomic world. When the pulses hit the atoms in a material, the electrons scatter like a wave.
By setting up a detector and analyzing the wave interference pattern, scientists can determine information like the distance between atoms.
Conventional electron pulse technology uses a static magnetic field to compress the electrons transversely. However, the static field can interfere with the electron source and the sample and lead to temporal distortion of the electron pulses--both
of which can lead to lower quality images. To avoid the problems associated with static field compression the MIT
and SIMTECH team proposed the first all-optical scheme for compressing electron pulses in three dimensions
and demonstrated the viability of the scheme via first-principle numerical simulations. In the scheme, laser pulses, functioning as three-dimensional lenses in both time and space, can compress electron pulses to attosecond durations and sub-micrometer dimensions,
providing a new way to generate ultrashort electron pulses for ultrafast imaging of attosecond phenomena."
"Using this scheme, one can compress electron pulses by as much as two to three orders of magnitude in any dimension or dimensions with experimentally achievable laser pulses.
This translates, for instance, to reducing the duration of an electron pulse from hundreds of femtoseconds to sub-femtosecond scales,
"said Liang Jie Wong, the lead researcher on the team, who is now at the Singapore Institute of Manufacturing Technology
Compressing Electron Pulses In time and Space Short pulse durations are critical for high temporal resolution in ultrafast electron imaging techniques.
how molecules interact in a chemical reaction, or how the structure of a material or microorganism is affected by the introduction of external stimuli.
To ensure that the electron pulse arrives at the sample or detector with the desired properties in spite of inter-electron repulsion
ultrafast electron imaging setups usually require means to compress the electron pulse both transversely and longitudinally.
which are coils of wire that create uniform magnetic fields, to focus the electron beams. The use of static field elements can lead to the undesirable presence of static magnetic fields on the electron source (cathode)
and the sample and can also cause temporal distortions when transporting ultrashort electron pulses. To solve these problems,
Wong's team conceived an all-optical scheme that focuses electron pulses in three dimensions by using a special type of laser mode with an intensity"valley"(or minimum) in its transverse profile,
which is technically known as a"Hermite-Gaussian optical mode.""The pulsed laser modes successively strike the moving electrons at a slanting angle, fashioning a three-dimensional trap for the electrons."
"To compress the electron pulse along its direction of travel, for instance, the laser-electron interaction accelerates the back electrons
and decelerates the front electrons. As the electrons propagate, the back electrons catch up with the front electrons, leading to temporal compression of the electron pulse,
"Wong explained. The force that the optical field exerts on the electrons is called the optical ponderomotive force,
a time-averaged force that pushes charged particles in a time-varying field towards regions of lower intensity."
"Just as conventional lenses can be used to focus a light beam, our configuration can be used to focus an electron beam.
In our case, however, we can perform the focusing not only in the dimensions perpendicular to the direction of travel,
but also in the dimension parallel to the direction of travel. Hence, the entire setup can be seen as a spatiotemporal lens for electrons,
"Wong said. By modeling the fields with exact solutions of Maxwell equations and solving the Newton-Lorentz equation,
which together describe classical optical and electromagnetic behavior, Wong and his collaborators have analytically and numerically demonstrated the viability of their scheme.
Among their findings is the fact that the longitudinal compression is sensitive to the laser pulse incidence angle,
which is a function of the electron pulse velocity for optimal performance. A major cost-saving feature in the proposed scheme is the fact that a single optical pulse can be used to implement a succession of compression stages.
Since the scheme allows laser pulses to be recycled for further compression of the same electron pulse (not restricted to the same dimension),
Besides being of great interest in ultrafast electron imaging for compressing both single-and multi-electron pulses
the proposed scheme is potentially useful for focusing other particles such as accelerated protons and neutral atoms.
Broader applications include the creation of flat electron beams and the creation of ultrashort electron bunches for coherent terahertz emission in free-electron based terahertz generation schemes,
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