the new process is still a chemical reaction that depends on molecules purposely attached to the nanotubes, a process called functionalization.
which can easily create self-ordered arrays of sub-20 nm features through simple spin-coating and plasma treatments.
#Hematite're-growth'smoothes rough edges for clean energy harvest (Nanowerk News) Finding an efficient solar water splitting method to mine electron-rich hydrogen for clean
The team reevaluated hematite surface features using a synchrotron particle accelerator at the Lawrence Berkeley National Laboratory.
a one-atom thick form of carbon. Tunneling electrons from a scanning tunneling microscope tip excites phonons in graphene.
The image shows the graphene lattice with blue arrows indicating the motion direction of that carbon atoms for one of the low energy phonon modes in graphene.
Image: Wyrick/NIST) They report their findings in the June 19, 2015, issue of Physical Review Letters("Strong Asymmetric Charge Carrier Dependence in Inelastic Electron Tunneling Spectroscopy of Graphene Phonons").
"Carbon atoms in graphene sheets are arranged in a regularly repeating honeycomb-like latticea two-dimensional crystal. Like other crystals,
the forces that bond the atoms together cause the atoms to vibrate and spread the energy throughout the material,
One way to measure these tiny vibrations is to bounce electrons off the material and measure how much energy the electrons have transferred to the vibrating atoms.
But it's difficult. The technique, called inelastic electron tunneling spectroscopy, elicits only a small blip that can be hard to pick out over more raucous disturbances."
"Researchers are faced frequently with finding ways to measure smaller and smaller signals, "says NIST researcher Fabian Natterer,
such as that supplied by the electrons in a scanning tunneling microscope (STM). To filter the phonons'signal from other distractions,
NIST researchers used their STM to systematically alter the number of electrons moving through their graphene device.
As the number of electrons were varied, the unwanted signals also varied in energy, but the phonons remained fixed at their characteristic frequency.
Averaging the signals over the different electron concentrations diluted the annoying disturbances, but reinforced the phonon signals.
which become filled with electrons and stop the phonons from vibrating when we switch from hole to electron doping."
"The team notes that this effect is similar to resonance-induced effects seen in small molecules.
They speculate that if the same effect were happening here, it could mean that the systemgraphene
and STMIS mimicking a giant molecule, but say that they still don't have a firm theoretical foundation for
"Although surface atoms represent a minuscule fraction of the total number of atoms in a material, these atoms drive a large portion of the material's chemical interactions with its environment."
and provides information on both surface and bulk atoms simultaneously. Image: Jim Ciston, Berkeley Lab) Ciston is the lead
and corresponding author of a paper describing this new analytical method in the journal Nature Communications("Surface Determination Through Atomically Resolved Secondary Electron Imaging").
and improve material performance it is vital to know how the atoms are arranged at surfaces. While there are now many good methods for obtaining this information for rather flat surfaces,
""The beauty of this technique is that we can image surface atoms and bulk atoms simultaneously,"says co-author Zhu, a scientist at Brookhaven National Laboratory."
"Currently none of any existing methods can achieve this.""Scanning electron microscopy (SEM) is an excellent technique for studying surfaces
and bulk atoms simultaneously, retaining much of the surface sensitivity of traditional SEM through secondary electrons.
Secondary electrons are the result of a highly energized beam of electrons striking a material
and causing atoms in the material to emit energy in the form of electrons rather than photons.
As a large portion of secondary electrons are emitted from the surface of a material in addition to its bulk they are good resources for obtaining information about atomic surface structure.
"Existing secondary electron image simulation methods had to be extended to take into account contributions from valence orbitals in the material,
and analyzed in detail a series of HRSEM images of a particular arrangement of atoms at the surface of strontium titanate.
These experiments were coupled with careful secondary electron image simulations, density functional theory calculations, and aberration-corrected high resolution transmission electron microscopy."
and gather data about reactions that can be observed only as they are happening inside a battery("Probing Lithium Germanide Phase Evolution and Structural Change in a Germanium-in-Carbon nanotube Energy storage system").
"Why It Matterslithium-ion batteries have many uses besides powering cell phones and laptops. Developing safer, more powerful cells with longer life is a worldwide challenge,
Germanium can take on more lithium during the reaction than other materials-making it a promising component for delivering higher battery capacity and superior discharge speeds,
Germanium is less abundant and more costly than other materials, such as silicon or carbon, but high battery performance resulting from its favorable uptake of lithium may be a factor in making lithium-germanide batteries attractive in the marketplace.
When the companion element-in this case germanium-takes up lithium, the volume of the electrode expands dramatically.
the scientists found a way to protect the germanium from expanding and becoming ineffective after it takes on lithium.
The secret proved to be forming the germanium into tiny"wires "and encasing them in small,
Without embedding germanium in carbon tubes, a battery performs well for a few charging-discharging cycles,
Metal-organic frameworks, briefly called MOFS, consist of two basic elements, metal node points and organic molecules,
Nature uses porphyrines as universal molecules e g. in hemoglobin and chlorophyll, where these organic dyes convert light into chemical energy.
The clou is that we just need a single organic molecule in the solar cell, Wll says.
The researchers expect that the photovoltaic capacity of the material may be increased considerably in the future by filling the pores in the crystalline lattice structure with molecules that can release
In photosynthesis, plants that are exposed to sunlight use carefully organized nanoscale structures within their cells to rapidly separate charges pulling electrons away from the positively charged molecule that is left behind,
The polymer donor absorbs sunlight and passes electrons to the fullerene acceptor; the process generates electrical energy.
because the electrons sometimes hop back to the polymer spaghetti and are lost. The UCLA technology arranges the elements more neatly like small bundles of uncooked spaghetti with precisely placed meatballs.
The fullerenes inside the structure take electrons from the polymers and toss them to the outside fullerene
which can effectively keep the electrons away from the polymer for weeks. When the charges never come back together,
led the team that created the uniquely designed molecules. We dont have these materials in a real device yet;
This force causes an increasing percentage of electrons to start flowing in the rongdirection as the magnetic field is ramped up,
Superfast electrons cause extremely large magnetoresistance he faster the electrons in the material move, the greater the Lorentz force and thus the effect of a magnetic field, explains Binghai Yan, a researcher at the Max Planck Institute for Chemical Physics of Solids in Dresden.
and phosphorus. This material contains superfast charge carriers, known as relativistic electrons that move at around one thousandth the speed of light,
In the process, they discovered why the electrons are so fast and mobile. The material owes its exotic properties to unusual electronic states in niobium phosphide.
Some electrons in this material, known as a Weyl metal act as if they have no mass. As a result, they are able to move very rapidly.
where molecules are designed to spontaneously assemble into desired structures. Self-assembly requires a burst of heat to make the molecules snap into the proper configurations.
Here an intensely hot laser swept across the sample to transform disordered polymer blocks into precise arrangements in just seconds."
These molecules then glom onto the self-assembled polymer, converting it into a metallic mesh.
with silicon germanium technology to create CMOS chips. It is fully compatible with current high volume chip fabrication technology,
Integrating high quality III-V materials on silicon is critical for getting the benefit of higher electron mobility to build transistors with improved power and performance for technology scaling at 7 nm and beyond.
an exciting world-record performance,'said study co-author Yi Cui, an associate professor of materials science and engineering at Stanford and of photon science at the SLAC National Accelerator Laboratory.
In an engineering first, Cui and his colleagues used lithium-ion battery technology to create one low-cost catalyst that is capable of driving the entire water-splitting reaction.'
'Our group has pioneered the idea of using lithium-ion batteries to search for catalysts, 'Cui said.'
A low-voltage current applied to the electrodes drives a catalytic reaction that separates molecules of H2o, releasing bubbles of hydrogen on one electrode and oxygen on the other.
The idea is to use lithium ions to chemically break the metal oxide catalyst into smaller and smaller pieces.'
'Breaking down metal oxide into tiny particles increases its surface area and exposes lots of ultra-small,
'This process creates tiny particles that are connected strongly, so the catalyst has very good electrical conductivity and stability.'
#New technique for'seeing'ions at work in a supercapacitor Researchers from the University of Cambridge, together with French collaborators based in Toulouse,
the researchers were able to visualise how ions move around in a supercapacitor. They found that
electrolyte ions are stored in the anode. As the battery discharges, electrolyte ions leave the anode
and move across the battery to chemically react with the cathode. The electrons necessary for this reaction travel through the external circuit,
generating an electric current. A supercapacitor is similar to a battery in that it can generate and store electric current,
instead, positive and negative electrolyte ions simply tickto the surfaces of the electrodes when the supercapacitor is being charged.
the ions can easily opoff the surface and move back into the electrolyte. The reason why supercapacitors charge
and discharge so much faster is that the tickingand oppingprocesses happen much faster than the chemical reactions at work in a battery. o increase the area for ions to stick to,
like a carbon sponge, said Griffin. ut it hard to know what the ions are doing inside the holes within the electrode we don know exactly what happens
and the positive ions are attracted to the surface as the supercapacitor charges. But in the positive electrode, an ion xchangehappens,
as negative ions are attracted to the surface, while at the same time, positive ions are repelled away from the surface.
Additionally, the EQCM was used to detect tiny changes in the weight of the electrode as ions enter and leave.
This enabled the researchers to show that solvent molecules also accompany the ions into the electrode as it charges. e can now accurately count the number of ions involved in the charge storage process
and see in detail exactly how the energy is stored, said Griffin. n the future we can look at how changing the size of the holes in the electrode
and the ion properties changes the charging mechanism. This way we can tailor the properties of both components to maximise the amount of energy that is stored.
The next step, said Professor Clare P. Grey, the senior author on the paper, s to use this new approach to understand why different ions behave differently on charging, an ultimately design systems with much higher capacitances. i
#Smart insulin patch could replace injections for diabetes Painful insulin injections could become a thing of the past for the millions of Americans who suffer from diabetes, thanks to a new invention from researchers at North carolina State university and the University
The researchers connected the two to create a new molecule, with one end that was water-loving
A mixture of these molecules self-assembled into a vesicle, much like the coalescing of oil droplets in water,
The resulting lack of oxygen or ypoxiamade the hydrophobic NI molecules turn hydrophilic, causing the vesicles to rapidly fall apart
Using an engineered strain of Stenotrophomonas maltophilia to control particle size the team biosynthesized QDS using bacteria
"builds on recent research by the same team that previously identified a fat-and-sugar molecule called GSL as the chief culprit behind a range of biological glitches that affect the body's ability to properly use, transport
The newly published report reveals the scientists appear to have cleared that hurdle by encapsulating D-PDMP into tiny molecules,
and track the nanoparticles'movement inside the animals'bodies by tagging them with a radioactive tracer that lit up on a CT SCAN.
Mice treated with placebo showed high levels of GSL--the molecule responsible for altered cholesterol metabolism
when particle size falls to the range of a few ten nanometers where a single particle provides only a vanishingly small signal.
As a consequence, many investigations are limited to large ensembles of particles. Now, a team of scientists of the Laser spectroscopy Division of Prof.
There is thus a large interest to develop single-particle-sensitive techniques. Our approach is to trap the probe light used for imaging inside of an optical resonator,
in order to bring the particle step by step into its focus. At the same time the distance between both mirrors is adjusted such that the condition for the appearance of resonance modes is fulfilled.
we can determine the optical properties of the particles from the transmission signal quantitatively and compare it to the calculation.
when both absorptive and dispersive properties of a single particle were determined at the same time. This is interesting especially
if the particles are not spherical but e g. elongated. Then, the corresponding quantities depend on the orientation of the polarization of light with respect to the symmetry axes of the particle.
In our experiment we use gold nanorods (34x25x25 nm) and we observe how the resonance frequency shifts depending on the orientation of the polarization.
and is a very sensitive indicator for the shape and orientation of the particle. As an application of our method, we could think of e g. investigating the temporal dynamics of macro molecules,
such as the folding dynamics of proteins says David Hunger. Overall we see a large potential for our method:
The interaction between liquid crystal molecules and plasmon waves on the nanostructured metallic surface played the key role in generating the polarization-independent
#Spintronics advance brings wafer-scale quantum devices closer to reality (Nanowerk News) An electronics technology that uses the"spin
and process information promises huge gains in performance over today's electron-based devices. But getting there is proving challenging.
They have gotten nuclear spins to line themselves up in a consistent, controllable way, and they have done it using a high-performance material that is practical, convenient,
Light polarizes silicon nuclear spins within a silicon carbide chip. This image portrays the nuclear spin of one of the atoms shown in the full crystal lattice below.
Image: Peter Allen)" Our results could lead to new technologies like ultra-sensitive magnetic resonance imaging, nuclear gyroscopes,
which was featured as the cover article of the June 17 issue of Physical Review Letters("Optical Polarization of Nuclear spins in Silicon Carbine").
"Falk and colleagues in David Awschalom's IME research group invented a new technique that uses infrared light to align spins.
Nuclear spins tend to be oriented randomly. Aligning them in a controllable fashion is complicated usually a and only marginally successful proposition.
is that"the magnetic moment of each nucleus is tiny, roughly 1, 000 times smaller than that of an electron."
"This small magnetic moment means that little thermal kicks from surrounding atoms or electrons can easily randomize the direction of the nuclear spins.
Extreme experimental conditions such as high magnetic fields and cryogenic temperatures(-238 degrees Fahrenehit and below) are required usually to get even a small number of spins to line up.
In magnetic resonance imaging (MRI), for example, only one to 10 out of a million nuclear spins can be aligned and seen in the image, even with a high magnetic field applied.
Using their new technique, Awschalom and his associates aligned more than 99 percent of spins in certain nuclei in silicon carbide (Sic).
Equally important, the technique works at room temperature--no cryogenics or intense magnetic fields needed. Instead, the research team used light to"cool"the nuclei.
The electron spins in these color centers can be cooled readily optically and aligned, and this alignment can be transferred to nearby nuclei.
had tried the group to achieve the same degree of spin alignment without optical cooling they would have had to chill the Sic chip physically to just five millionths of a degree above absolute zero(-459.6 degrees Fahrenheit.
Getting spins to align in room-temperature silicon carbide brings practical spintronic devices a significant step closer,
"Wafer-scale quantum technologies that harness nuclear spins as subatomic elements may appear more quickly than we anticipated
Molecules are transported into the nucleus or from the nucleus into the cytoplasm. In a human cell, more than a million molecules are transported into the cell nucleus every minute.
In the process, special pores embedded in the nucleus membrane act as transport gates. These nuclear pores are among the largest and most complex structures in the cell
which small molecules can pass unobstructed, while large molecules have to meet certain criteria to be transported.
Now for the first time, an University of Zurich research team headed by Professor Ohad Medalia has succeeded in displaying the spatial structure of the transport channel in the nuclear pores in high resolution (Nature Communications,
which can only be opened by molecules that hold the right key, "explains Medalia. This"molecular gate"is the so-called spoke ring,
which enables small molecules to slip through unobstructed. The new, high-resolution presentation of the nuclear pore structure leads to a better understanding of why certain molecules are allowed to pass through the nuclear pores
while others are turned away. It also helps improve our understanding of the development of some diseases that involve a defective transportation to the nuclear pores-such as intestinal ovarian and thyroid cancer r
#Helium'balloons'offer new path to control complex materials (Nanowerk News) Researchers at the Department of energy's Oak ridge National Laboratory have developed a new method to manipulate a wide range of materials
and their behavior using only a handful of helium ions. The team's technique, published in Physical Review Letters("Strain doping:
Reversible single axis control of a complex oxide lattice via helium implantation.""advances the understanding and use of complex oxide materials that boast unusual properties such as superconductivity and colossal magnetoresistance but are notoriously difficult to control.
Inserting helium atoms (visualized as a red balloon) into a crystalline film (gold) allowed Oak ridge National Laboratory researchers to control the material's elongation in a single direction.
This is accomplished by adding a few helium ions into a complex oxide material and provides a never before possible level of control over magnetic and electronic properties."
"By putting a little helium into the material, we're able to control strain along a single axis,
"The intricate way in which electrons are bound inside complex oxides means that any strain--stretching,
as it can be implemented using established ion implantation infrastructure in the semiconductor industry, "Ward said. The method uses a low energy ion gun to add small numbers of helium ions into the material after it has been produced.
The process is also reversible; the helium can be removed by heating the material to high temperatures in vacuum.
Previously developed strain tuning methods modify all directions in a material and cannot be altered or reversed afterwards."
"By controlling the number of helium atoms inserted into an epitaxial film, we select a strain state in one direction
Since this time, scientists and engineers have developed many two-dimensional (2d) material innovations--layered materials with the thickness of only one atom or a few atoms.
Professor Jim Williams, Professor Andrei Rode and Associate professor Jodie Bradbury with the complex electron diffraction patterns.
Using a combination of electron diffraction patterns and structure predictions, the team discovered the new materials have crystal structures that repeat every 12,
16 or 32 atoms respectively, said Professor Jim Williams, from the Electronic Material Engineering group at RSPE."
and solidify before they can decay, said Professor Eugene Gamaly, also from the ANU Research School of Physics and Engineering.
"The semiconductor industry is a multi-billion dollar operation-even a small change in the position of a few silicon atoms has the potential to have a major impact
The movement of electrons caused by friction was able to generate enough energy to power the lights
#Graphene flexes its electronic muscles Flexing graphene may be the most basic way to control its electrical properties, according to calculations by theoretical physicists at Rice university and in Russia.
Perfect graphene an atom-thick sheet of carbon is a conductor, as its atomselectrical charges balance each other out across the plane.
But curvature in graphene compresses the electron clouds of the bonds on the concave side and stretches them on the convex side,
the characteristic that controls how polarized atoms interact with external electric fields. The researchers who published their results this month in the American Chemical Society Journal of Physical chemistry Letters discovered they could calculate the flexoelectric effect of graphene rolled into a cone of any size and length.
The researchers used density functional theory to compute dipole moments for individual atoms in a graphene lattice
in which the balance of positive and negative charges differ from one atom to the next, due to slightly different stresses on the bonds as the diameter changes.
The researchers noted atoms along the edge also contribute electrically, but analyzing two cones docked edge-to-edge allowed them to cancel out,
#Atomic force microscope advance leads to new breast cancer research (Nanowerk News) Researchers who developed a high-speed form of atomic force microscopy have shown how to image the physical properties of live breast cancer cells,
In atomic force microscopy (AFM), a tiny vibrating probe called a cantilever passes over a material precisely characterizing its topography and physical properties.
and radiation and are believed to play an important role in tumor recurrence. This laboratory and animal study showed that nanoparticles coated with the oligosaccharide called chitosan
couple the fermentation molecules into an intermediate product consisting of long-chain alcohols and ketones.
The research is detailed in"Reversible Electron Storage in an All-Vanadium Photoelectrochemical Storage cell: Synergy between Vanadium Redox and Hybrid Photocatalyst",in the most recent edition of the American Chemical Society journal ACS Catalysis. Khosrow Behbehani, dean of the College of Engineering, said the groundbreaking research has the potential
"We have demonstrated simultaneously reversible storage of both solar energy and electrons in the cell, "Dong Liu said."
"Release of the stored electrons under dark conditions continues solar energy storage, thus allowing for unintermittent storage around the clock."
Caltech researchers adopted a novel technique, ultrafast electron crystallography (UEC), to visualize directly in four dimensions the changing atomic configurations of the materials undergoing the phase changes.
"Today, nanosecond lasersasers that pulse light at one-billionth of a secondre used to record information on DVDS and Blu-ray disks,
Thus, with a nanosecond laser,"the fastest you can record information is one information unit
one 0 or 1, every nanosecond,"says Jianbo Hu, a postdoctoral scholar and the first author of the paper."
"To study this, the researchers used their technique, ultrafast electron crystallography. The technique, a new developmentifferent from Zewail's Nobel Prizeinning work in femtochemistry, the visual study of chemical processes occurring at femtosecond scalesllowed researchers to observe directly the transitioning atomic configuration of a prototypical phase-change material
, germanium telluride (Gete), when it is hit by a femtosecond laser pulse. In UEC, a sample of crystalline Gete is bombarded with a femtosecond laser pulse,
followed by a pulse of electrons. The laser pulse causes the atomic structure to change from the crystalline to other structures,
when the electron pulse hits the sample, its electrons scatter in a pattern that provides a picture of the sample's atomic configuration as a function of the time.
Thanks to their low weight, high energy density and slower loss of charge when not in use, LIBS have become the preferred choice for consumer electronics.
Lithium-ion cells with cobalt cathodes hold twice the energy of a nickel-based battery and four times that of lead acid.
and highly anisotropic directionally dependent proton conducting behaviors in porous CB 6 for fuel cell electrolytes.
It is possible for this lithium ion conduction following porous CB 6 to be safer than existing solid lithium electrolyte-based organic-molecular porous-materials utilizing the simple soaking method
The new battery is built from pumpkin-shaped molecules called cucurbit 6 uril (CB 6) which are organized in a honeycomb-like structure.
The molecules have an incredibly thin 1d-channel, only averaging 7. 5 Å a single lithium ion is 0. 76 Å,
or. 76 x 10-10 m that runs through them. The physical structure of the porous CB 6 enables the lithium ions to battery to diffuse more freely than in conventional LIBS
and exist without the separators found in other batteries. In tests the porous CB 6 solid electrolytes showed impressive lithium ion conductivity.
To compare this to existing battery electrolytes, the team used a measurement of the lithium transference number (tli)
which the synthesis of a specific protein is inhibited, by real time observation of target RNA cleavage at the single-molecule level.
and at Kyoto University (Researcher Hisashi Tadakuma), has developed a single-molecule imaging assay for observing target RNA cleavage by RISC in a test tube in real time for the first time,
Overtext Web Module V3.0 Alpha
Copyright Semantic-Knowledge, 1994-2011