#Nanoparticle network could bring fast-charging batteries (Phys. org) A new electrode design for lithium-ion batteries has been shown to potentially reduce the charging time from hours to minutes by replacing the conventional graphite electrode with a network of tin-oxide nanoparticles.
The anodes in most of today's lithium-ion batteries are made of graphite. The theoretical maximum storage capacity of graphite is limited very at 372 milliamp hours per gram hindering significant advances in battery technology said Vilas Pol an associate professor of chemical engineering at Purdue University.
In the human body, Vitamin c makes free radicals harmless by transferring electrons to them.""Gold precipitation functions according to the same principle.
but rather gold ions",explains Falk Münch, a postdoctoral researcher and supervisor of Felix'Phd thesis. The gold ions that are dissolved in the precipitation bath are transformed into metallic gold after absorbing electrons.
Additional, harmless chemicals are required for the process. But the procedure is green not only because of the nontoxic substances,
a round film is bombarded vertically with an ion beam. Each ion leaves a straight track in the film
which then becomes a small hole, or, when seen through the microscope: a channel that is then etched.
an ion accelerator is needed to generate an ion beam. The TU scientists found the ideal partner for their research in the GSI Helmholtz Center for Heavy ion Research at the outskirts of Darmstadt;
but the GSI's large-scale accelerator was not suitable for subsequent commercial use for financial reasons.
The TU scientists are already looking for alternatives. For example, a company in the USA produces similarly perforated films with smaller accelerators."
"The films are defined not as well as ours are, but they are also suitable, "says Münch.
catalyzed by the gold releases electrons generates an easily measurable electric current. The gold nanotubes conduct electricity especially well due to their one-dimensional structure.
but direct imaging of sub-10-nanometer particles is nearly impossible. That's where we came up with the idea of using templates based on channels with gradually varying widths says co-author Mohamed Asbahi.
Using electron-beam lithography techniques the team carved out an array of inward tapering trenches designed to fit 1 to 3 rows of gold nanoparticles.
After depositing a monolayer of 8-nanometer particles in the template they used scanning electron microscopy to identify any emergent width-dependent patterns.
The success of DSA-n depends on the positioning accuracy of the particles says Yang. By exploiting the rich set of structural geometries that exist between ordered states we can design templates that guide particles into complex periodic and nonperiodic structures s
#Lengthening the life of high capacity silicon electrodes in rechargeable lithium batteries A new study will help researchers create longer-lasting higher-capacity lithium rechargeable batteries
The coated silicon particles lasted at least five times longer#uncoated particles died by 30 cycles but the coated ones still carried a charge after 150 cycles.
and is currently the only group that can create alucone-coated silicon particles#took high magnification images of the particles in an electron microscope.
But Wang's team has a microscope that can view the particles in action while they are being charged and discharged.
and limits how much lithium the particle can take in when a battery charges. At the same time they found that the alucone coating softens the particles making it easier for them to expand
and shrink with lithium. And the microscopic images revealed something else#the rubbery alucone replaces the hard oxide.
But this molecular deposition method that coats the particles completely changed the protective layer. In addition the particles with the oxide shells tend to merge together during charging increasing their size
and preventing lithium from permeating the silicon. The rubbery coating kept the particles separated allowing them to function optimally.
In the future the researchers would like to develop an easier method of coating the silicon nanoparticles. Explore further:
Silicon sponge improves lithium-ion battery performance More information: Yang He Daniela Molina Piper Menggu Jonathan J. Travis Steven M. George Se-Hee Lee Arda Genc Lee Pullan Jun Liu
Yael Hanein of Tel aviv University's School of Electrical engineering and head of TAU's Center for Nanoscience and Nanotechnology and including researchers from TAU the Hebrew University of Jerusalem and Newcastle University.
According to TAU doctoral student and research team member Dr. Lilach Bareket there are already medical devices that attempt to treat visual impairment by sending sensory signals to the brain.
Computer simulations sharpen insights into molecules The resolution of scanning tunnelling microscopes can be improved dramatically by attaching small molecules or atoms to their tip.
The resulting images were the first to show the geometric structure of molecules and have generated a lot of interest among scientists over the last few years.
"Together with his colleagues from the Peter Grünberg Institute (PGI-3), in 2008 Tautz introduced the method of attaching single molecules initially hydrogen molecules,
later molecules such as carbon monoxide to the tip of a scanning tunnelling microscope and using them as extremely sensitive measuring probes.
It enables scanning tunnelling microscopes to be used as a kind of atomic force microscope that is able to image the geometric structure of molecules with unprecedented accuracy."
"The valence charge clouds of complex organic molecules often spread over the entire molecule, thus concealing its atomic structure,
Flexibly bound molecules at the microscope tip can be utilized as tailor-made sensors and signal transducers that are able to make the atomic structure visible nevertheless.
Then, in May 2014, scientists from the University of California, Irvine, showed for the first time that these sensors can also be used to improve signals in a related imaging mode known as inelastic electron tunnelling spectroscopy.
it is the vibration of the sensor molecule against the microscope tip that reacts sensitively to the surface potential of the scanned sample."
"We believe that the results of this work are an important contribution to the use of inelastic electron tunnelling spectroscopy that will allow the technique to be used as an additional source of information in materials science
#Protons fuel graphene prospects Graphene impermeable to all gases and liquids can easily allow protons to pass through it,
and other hydrogen-based technologies as they require a barrier that only allow protons-hydrogen atoms stripped off their electrons-to pass through.
One-atom thick material graphene first isolated and explored in 2004 by a team at The University of Manchester is renowned for its barrier properties
For example it would take the lifetime of the universe for hydrogen the smallest of all atoms to pierce a graphene monolayer.
whether protons are repelled also by graphene. They fully expected that protons would be blocked as existing theory predicted as little proton permeation as for hydrogen.
Despite the pessimistic prognosis the researchers found that protons pass through the ultra-thin crystals surprisingly easily especially at elevated temperatures
and if the films were covered with catalytic nanoparticles such as platinum. The discovery makes monolayers of graphene
and its sister material boron nitride attractive for possible uses as proton-conducting membranes which are at the heart of modern fuel cell technology.
Without membranes that allow an exclusive flow of protons but prevent other species to pass through this technology would not exist.
One of the major problems is a fuel crossover through the existing proton membranes which reduces their efficiency and durability.
The Manchester group also demonstrated that their one-atom-thick membranes can be used to extract hydrogen from a humid atmosphere.
They posses a high surface area for better electron transfer which can lead to the improved performance of an electrode in an electric double capacitor or battery.
Last a technique known as anisotropic ion beam milling (IBM) is used to etch through the mask to make an array of holes creating the nanoporous metal.
Other applications of nanoporous metals include supporting the development of new metamaterials (engineered materials) for radiation-enhanced filtering
revealing how they selectively block certain molecules from entering, protecting genetic material and normal cell functions.
but this must open enough to let vital molecules in and out, so the membrane is pierced by hundreds of tiny gateways known as nuclear pores.
filtering molecules by size but also based on chemical properties. Co-lead author Dr Bart Hoogenboom, from the London Centre for Nanotechnology (UCL Mathematics & Physical sciences), said:"
which allows small molecules and salts to flow through without any trouble. Larger molecules, like MESSENGER RNA, can only pass
when accompanied by chaperone molecules. These chaperones, called nuclear transport receptors, have the property of lubricating the strands
and relaxing the barrier, letting the larger molecules through. This can happen up to several thousand times per second."
"Before now, scientists understood the overall shape of the pores and that protein structures in the middle of them controlled the flow of molecules,
but it was known not how they did this. Some theories suggested the pores acted like a brush and others like a sieve.
The team used a technique known as atomic force microscopy (AFM) to study the pores. Much like people can use their fingers to read braille
but it allows us to come up with far better maps of small objects than is possible with other methods-even individual atoms can be observed this way.
and protein diagnostic devices into every single doctor's office said Stuart Lindsay an ASU physics professor and director of Biodesign's Center for Single Molecule Biophysics.
The technology we've developed might just be the first big step in building a single-molecule sequencing device based on ordinary computer chip technology said Lindsay.
and gives DNA molecules room to pass the electrodes. Specifically when a current is passed through the nanopore as the DNA passes through it causes a spike in the current unique to each chemical base (A c T or G) within the DNA molecule.
A few more modifications are made to polish and finish the device manufacturing. The team encountered considerable device-to-device variation
And the final big step-of reducing the diameter of the hole through the device to that of a single DNA molecule-has yet to be taken.
The research team is also working on modifying the technique to read other single molecules which could be used in an important technology for drug development.
With this technology a low-power laser beam is directed at the tumor where a small amount of magnetic iron-oxide nanoparticles are present either by injecting the particles directly into the tumor
whereby the particles find and bind to the abnormal cancer cells via cell-specific targeting. Sufficient heat is generated then locally by the laser light raising the tumor temperature rapidly to above 43 degrees Celsius
and unlock their florescent particles so they can be detected by a photon laser light. The laser light heats the nanoparticles to at least 43 degrees Celsius to kill the cancer cells ultimately leaving all the other cells in the body unharmed.
The procedure can ultimately be carried out by the patient following training to direct a small laser light device to the affected area for a specified amount of time two to three times a day.
This new biomarker which has immense potential for drug development is made from a nanophosphor particle ten thousand times smaller than a grain of sand.
and only if tumour cells release small signalling molecules. Prof Zhang said the use of near-infrared light which is invisible to the human eye is unique as most imaging techniques use ultraviolet light or visible light.
Hu's team wanted to develop a way to print it directly on paper to make a sensor that could respond to touch or specific molecules such as glucose.
these particles can form dangerous, highly reactive chemicals called free radicals that can damage DNA. Because light does not reach the human body's interior,
"We didn't set out to test the safety of the particles themselveshat's for someone else to determine,
Gaharwar and his colleagues employ two-dimensional, disc-shaped particles known as synthetic silicate nanoplatelets. Because of their shape, these platelets have a high surface area,
The structure, composition and arrangement of the platelets result in both positive and negative charges on each particle.
Through this project Fan developed a faster way of treating the biochar particles using a new technology called plasma activation.
which cover conductive titanium dioxide particles. The dyes absorb photons and produce electrons that flow out of the cell for use;
a return line completes the circuit to the cathode that combines with an iodine-based electrolyte to refresh the dye.
While they are not nearly as efficient as silicon-based solar cells in collecting sunlight and transforming it into electricity,
allowing electrons to flow more freely. The new cathode's charge-transfer resistance, which determines how well electrons cross from the electrode to the electrolyte,
was found to be 20 times smaller than for platinum-based cathodes, Lou said. The key appears to be the hybrid's huge surface area,
and provides a highly conductive path for electrons. Lou's lab built and tested solar cells with nanotube forests of varying lengths The shortest,
titanium dioxide and light-capturing organic dye particles, the largest cells were only 350 microns thickhe equivalent of about two sheets of papernd could be flexed easily and repeatedly.
These tiny platelet-shaped particles that behave just like their human counterparts can be added to the blood flow to supply
According to Anselmo's investigations for the same surface properties and shape nanoscale particles can perform even better than micron-size platelets.
Additionally this technology allows for customization of the particles with other therapeutic substances medications therapies
Particles could be made to fulfill certain requirements to travel to certain parts of the body across the blood-brain barrier for instance for better diagnostics
which are only one atom thick onto arbitrary substrates paving the way for flexible computing or photonic devices.
At issue are molybdenum sulfide (Mos2) thin films that are only one atom thick first developed by Dr. Linyou Cao an assistant professor of materials science and engineering at NC State.
Cao's team makes Mos2 films that are an atom thick and up to 5 centimeters in diameter.
To put that challenge in perspective an atom-thick thin film that is 5 centimeters wide is equivalent to a piece of paper that is as wide as a large city Cao said.
and use less power is pushing the limits of the properties of electrons in a material.
Double stranded-rna RNA is synthesized a molecule that can trigger a biological process known as RNA interference or RNAI to destroy the genetic code of an insect in a specific DNA sequence.
Our dsrna molecules were designed based on specific gene sequences of the mosquito Zhu said. You can design species-specific dsrna for the same or different genes for other insect pests.
Working at the Center for Nanoscale Materials (CNM)/ X-ray Science Division 26-ID beamline of the U s. Department of energy's Advanced Photon Source the researchers took advantage of some new technological innovations
The resolution and sensitivity of STM can be affected adversely by photoejected electrons from the sample interfering with the measurement of tunneling effects.
and patented a nanofabricated smart tip for the scanning tunneling microscope that sharply focuses detection of electrons solely to those collected at the scanning tip where it interacts with the sample ignoring the background electrons from the sidewalls of the tip.
and then the tip apex was exposed via focused ion beam milling carried out at the CNM Electron microscopy Center (EMC).(
Both that remarkable resolution and the precise chemical fingerprinting of individual nickel nanoclusters were also clearly evident in the topographic images of the sample surface even down to the height of a single atom.
-and compressive strength-its ability to support weight-are valuable characteristics for these materials because at just a few atoms thick their utility figures almost entirely on their physical versatility.
Take the electrode of the small lithium-ion battery that powers your watch for example ideally the conductive material in that electrode would be very small
This allows the molecules to settle between the layers of the MXENE and in doing
The uniqueness of MXENES comes from the fact that their surface is full of functional groups such as hydroxyl leading to a tight bonding between the MXENE flakes and polymer molecules while preserving the metallic conductivity of nanometer-thin
because it slightly enlarges the interlayer space between MXENE flakes allowing ions to penetrate deep into the electrode;
ions also stay trapped near the MXENE flakes by the polymer. With these conductive electrodes and no liquid electrolyte we can eventually eliminate metal current collectors
whereas others can be made in the lab sometimes from complex biological molecules. No says Graham.
On a technical level they're talking about magnetic particles so you'd assume that'd be made something of iron
In Professor Graham's view there are two serious hurdles for nanotechnologists to overcome before particle-based biosensing becomes a reality:
So for Google's biomonitor they need to work out how to keep the particles in the body
'This is where random nonspecific molecules stick to the nanoparticles and clog them up or deactivate them.
Using electron beam lithography she then stamps the pattern onto a polymer matrix and the nanowires are grown by applying electric current through electrodeposition.
In synovial fluid found in joints for example hyaluronic acid molecules arrange themselves into networklike structures that result in a high viscosity.
whose molecules cross-link to form gel-like and therefore highly viscous structures explains co-author Debora Schamel a doctoral student at the Max Planck Institute in Stuttgart.
Previous artificial structures were too large to penetrate the tightly woven network of hyaluronan molecules. Debora Schamel is pleased
The hot spot was created by photon-to-heat conversion of a gold nanorod.""We believe our approach opens new avenues for simultaneous electrical and optical nanopore DNA sequencing
single-molecule DNA sequencing. DNA molecules can be labeled with fluorescent dyes so that each base-pair fluoresces at a signature intensity as it passes through the junction of the nanopore and its optical antenna."
"In addition, either the gold nanoplasmonic optical antenna or the graphene can be functionalized to be responsive to different base-pair combinations,
and exciting quantum systems. Why is This Discovery so Important? For many years, researchers observed that quality factors decreased with the volume of the resonator, that is the smaller the resonator the lower the quality factor,
For instance, nanotube resonators might be used to detect individual nuclear spins, which would be an important step towards magnetic resonance imaging (MRI) with a spatial resolution at the atomic level.
The widely used method of metamaterial synthesis is top-down fabrication such as electron beam or focus ion beam lithography that often results in strongly anisotropic and small-scale metamaterials.
People build metamaterials using top-down methods that include light exposure and electron beam exposure which are inefficient and costly says Xingjie Ni another lead author on the paper.
If we want to use metamaterials we need to develop a way to build them cheaply and efficiently.
The team used a laser to excite the plasmonic resonance of specific particles produced in the reaction.
Then the reaction can be repeated to produce more of the desired broken-symmetry particles based on their plasmonic signature.
Molybdenum disulfide isn't quite as flat as graphene the atom-thick form of pure carbon
because it contains both molybdenum and sulfur atoms. When viewed from above it looks like graphene with rows of ordered hexagons.
But seen from the side three distinct layers are revealed with sulfur atoms in their own planes above and below the molybdenum.
and high electrical conductivity and are used in products from baseball bats and other sports equipment to lithium-ion batteries and touchscreen computer displays.
When the sensor detects molecules from an explosive, deadly gas or drugs such as methamphetamine, they alter the electrical current through the nanotube materials,
which analyze the spectra of ionized molecules of explosives and chemicals, the Utah carbon nanotube technology has four advantages s
#A quantum leap in nanoparticle efficiency (Phys. org) New research has unlocked the secrets of efficiency in nanomaterials that is materials with very tiny particles
In an international study University of Melbourne and the National Institute of Standards and Technology in the US found that pairs of closely spaced nano particles made of gold can act as optical antennas.
These antennae concentrate the light shining on them into tiny regions located in the gap between the nano particles.
Researchers found the precise geometry of nanoparticle pairs that maximises light concentration resolving a hotly debated area of quantum physics.
what gap was required between particles to best concentrate the light but we now have the technology to test it.
Nanodiamonds are very small particles (a thousand times smaller than human hair) and because of their low toxicity they can be used as a carrier to transport drugs inside cells.
#Tracking heat-driven decay in leading electric vehicle batteries Rechargeable electric vehicles are one of the greatest tools against rising pollution and carbon emissions and their widespread adoption hinges on battery performance.
One particular family of lithium-ion batteries composed of nickel cobalt and aluminum (NCA) offers high enough energy density a measure of the stored electricity in the battery that it works well in large-scale and long-range vehicles including electric cars and commercial aircraft.
As the battery cycles lithium ions shuttle back and forth between cathode and anode and leave behind detectable tracks of nanoscale damage.
and spectroscopy techniques where beams of high-frequency photons bombard and bounce off a material to reveal elemental structure and composition.
The highly focused electron beams available at CFN revealed individual atom positions as an applied current pushed pristine batteries to an overcharged state.
To capture the atoms'electronic structures the scientists used electron energy loss spectroscopy (EELS. In this technique measurements of the energy lost by a well-defined electron beam reveal local charge densities and elemental configurations.
We found a decrease in nickel and an increase in the electron density of oxygen Hwang said.
This causes a charge imbalance that forces oxygen to break away and leave holes in the NCA surface permanently damaging the battery's capacity and performance.
Thermal decay and real-time electron microscopythe final study published in Applied materials and Interfaces used in situ electron microscopy to track the heat-driven decomposition of NCA materials at different states of charge.
but the real-time TEM revealed an unexpected twist within individual particles Stach said. When fully charged some particles released oxygen
and began to shift toward disorder down at temperatures below 100 degrees Celsius definitely plausible for a lithium-ion battery's normal operation.
Added Hwang Those unstable degraded particles may trigger the chain reaction of so-called thermal runaway at lower temperatures than expected
and that free oxygen would feed the fire springing from an overheated battery. The corroborating data in the three studies points to flaws in the chemistry
Molecular electronics, which uses molecules as building blocks for the fabrication of electronic components, was seen as the ultimate solution to the miniaturization challenge.
to date, no one has actually been able to make complex electrical circuits using molecules. The only known molecules that can be designed pre to self-assemble into complex miniature circuits,
which could in turn be used in computers, are DNA molecules. Nevertheless, so far no one has been able to demonstrate reliably and quantitatively the flow of electrical current through long DNA molecules.
Now, an international group led by Prof. Danny Porath, the Etta and Paul Schankerman Professor in Molecular Biomedicine at the Hebrew University of Jerusalem, reports reproducible and quantitative measurements of electricity flow through long molecules made of four
DNA strands signaling a significant breakthrough towards the development of DNA-based electrical circuits. The research,
which could reignite interest in the use of DNA-based wires and devices in the development of programmable circuits, appears in the prestigious journal Nature Nanotechnology under the title"Long-range charge transport in single G-quadruplex DNA molecules."
"Prof. Porath is affiliated with the Hebrew University's Institute of Chemistry and its Center for Nanoscience and Nanotechnology.
The molecules were produced by the group of Alexander Kotlyar from Tel aviv University, who has been collaborating with Porath for 15 years.
not only to look at the molecules next to the electrode surface but to determine their arrangement changes depending on the voltage.
and show how the interfacial molecules are arranged. XAS itself is not new. In this process a material absorbs x-ray photons at a specific rate as a function of photon energy.
A plot of the absorption intensity as a function of energy is referred to as a spectrum
which like a fingerprint is characteristic of a given material molecule and its chemical state.
The x-ray photons used in this study have energies that are about 250 times higher than those of visible light
Typical XAS measurements are made under vacuum conditions as x-rays are absorbed readily by matter even the nitrogen molecules in air.
or a tenth of a micrometer) x-ray transparent window with a thin coating of gold (20nm) on a sealed liquid sample holder the Berkeley Lab team was able to expose water molecules in the liquid to x-rays
Upon absorbing an x-ray photon the excited water molecule can spew (emit) either charged particles (electrons) or light (photons.
The amount of photon emission or fluorescence is one indicator of how many x-ray photons have been absorbed.
However fluorescing x-rays can be detected from molecules ranging from those at the gold surface to those deep (micrometers) inside the liquid far from the influence of the gold surface
and looking at the fluorescence photon signal we can't tell the difference between the interface
and the interior electrolyte molecules says Salmeron. The challenge therefore was to collect a signal that would be dominated by the interfacial region.
The team accomplished this by measuring electron emissions because electrons emitted from x-ray excited water molecules travel only nanometer distances through matter.
The electrons arriving at the gold electrode surface can be detected as an electrical current traveling through a wire attached to it.
This avoids confusion with signals from the interior electrolyte because electrons emitted from interior molecules don't travel far enough to be detected.
There's an additional problem that arises when studying liquids in contact with working electrodes because they carry a steady current as in batteries and other electrochemical systems.
While the emitted electrons from nearby molecules are indeed detectable this contribution to the current is dwarfed by the normal Faradaic current of the battery at finite voltages.
The current contribution resulting from electron emission by interfacial molecules is pulsed thus as well and instruments can separate this nanoampere modulated current from the main Faradaic current.
These experiments result in absorption vs. x-ray energy curves (spectra) that reflect how water molecules within nanometers of the gold surface absorb the x-rays.
we just choose what atomic elements are present and how many atoms. That's it. The chemistry is a result of the calculation.
It turns out that for a neutral gold surface a significant number of water molecules (H2o) next to the gold surface orient with hydrogen (H) atoms pointing toward the gold.
Water molecules are bound together by so-called hydrogen bonds which orient the slightly positively charged H atoms in each molecule towards the slightly negatively charged oxygen (O) atoms of neighboring molecules.
This network of hydrogen bonds is what holds water molecules together to make a liquid under conditions of temperature
and pressure that we consider comfortable as humans. It is perhaps surprising that the inert gold surface can induce significant numbers of water molecules not to hydrogen-bond to each other
but to bond to the gold instead. This number is enhanced when the gold is negatively charged
and therefore attracting the more positive H atoms. Furthermore positively charged gold ions cause water molecules to orient their H atoms away from the gold
which strengthens the hydrogen bond network of the interfacial liquid. That's the main thing we know about the gold electrode surface from the x-ray absorption spectra:
how many water molecules are tilted one way or another and if their hydrogen bonds are broken or not concludes Salmeron.
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