In a paper published Aug 10 in the journal Nature Communications, Michael Arnold, an associate professor of materials science and engineering at UW-Madison, Ph d. student Robert Jacobberger,
when it explored dramatically slowing the growth rate of the graphene crystals by decreasing the amount of methane in the chemical vapor deposition chamber.
the graphene crystals naturally grow into long nanoribbons on a specific crystal facet of germanium. By simply controlling the growth rate and growth time,
biocompatible polymer film made out of polyvinylidene fluoride, or PVDF. To improve the material's energy harvesting ability, they added DNA,
Related to these goals, we are developing approaches to inject and print gallium-based liquid metal alloys into varied materials for stretchable and reconfigurable electronics.
For energy devices we have demonstrated solution-processable approaches to fabricate organic photovoltaic devices on nearly arbitrary surfaces including PET and polymer reinforced polymer composites.
The presentation will also discuss the development of silver inks as an interconnect material for flexible Si CMOS ICS on elastomers.
'which are based on metals, polymers and organic materials, to tie the system together electronically. With our technology, we can take a razor-thin silicon integrated circuit, a few hundred nanometers thick,
the Wright-Patterson team has turned to liquid gallium alloys as an electrical interconnect material, Leever says."
"While these liquid alloys typically oxidize within minutes and become essentially useless, "he says, "the team has been able to dramatically reduce the effects of the oxidation through the use of ionic species confined to the walls of microvascular channels within the flexible substrates."
The work was done by researchers in the laboratories of Lewis and Harry Atwater, director of JCAP and Howard Hughes Professor of Applied Physics and Materials science."
Rare and expensive metals such as platinum can serve as effective catalysts, but in its work the team discovered that it could create a much cheaper,
and safety of the new system is the special plastic membrane that separates the gases
The magnetic phase state at the edges of the antidots raised the metal-to-insulator phase transition temperature of the manganite film.
"The waste material is free compared compared to all the metals and expensive organic chemicals needed in other processes-in my opinion this is a far easier way to go."
and photoluminescence to optically probe the molecular structure of the phthalocyanine crystals.""Marrying these two techniques together is new;
and the boundaries in the crystals influence the movement of excitons. It's these boundaries that form a"barrier for exciton diffusion,
the team worked in the lab of UVM physics and materials science professor Randy Headrick to successfully form films with jumbo-sized crystal grains and"small angle boundaries."
who directs UVM's program in materials science, "and to do that we need a deeper understanding of exciton diffusion.
A spin wave is caused by a perturbation of the local magnetisation direction in a magnetic material.
Research paves the way for alloys that are 3x stronger than steel yet bend like gum Abstract:
based on UNSW Australia research that can predict for the first time which combinations of metals will best form these useful materials.
Just like something from science fiction-think of the Liquid-Metal Man robot assassin (T-1000) in the Terminator films-these materials behave more like glass or plastic than metal.
While still being metals, they become as malleable as chewing gum when heated and can be moulded easily
They are also three times stronger and harder than ordinary metals on average, and are among the toughest materials known."
"They have been described as the most significant development in materials science since the discovery of plastics more than 50 years ago,"says study author, Dr Kevin Laws, from UNSW Australia in Sydney.
Most metals are crystalline when solid, with their atoms arranged in a highly organised and regular manner.
Metallic glass alloys, however, have disordered a highly structure, with the atoms arranged in a non-regular way."
"There are many types of metallic glass, with the most popular ones based on zirconium, palladium, magnesium, titanium or copper.
But until now, discovering alloy compositions that form these materials has required a lengthy process of trial and error in the laboratory,
They have used their model to successfully predict more than 200 new metallic glass alloys based on magnesium
"Metallic glass alloys are expensive to manufacture and to date have only been used in niche products,
Enclosed within the platelet membranes are made nanoparticle cores of a biodegradable polymer that can be metabolized safely by the body.
The nanoparticles can be packed with many small drug molecules that diffuse out of the polymer core and through the platelet membrane onto their targets.
The work, published Monday in the Proceedings of the National Academy of Sciences, pairs gold nanomesh with a stretchable substrate made with polydimethylsiloxane, or PDMS.
In materials science,"fatigue"is used to describe the structural damage to a material caused by repeated movement or pressure, known as"strain cycling."
and fatigue has been a deadly disease for metals, "the researchers wrote.""We weaken the constraint of the substrate by making the interface between the Au (gold) nanomesh and PDMS slippery,
patterned silica material laid on top of a traditional solar cell. The material is transparent to the visible sunlight that powers solar cells,
Despite the high performance of metallic implants, including titanium and its alloys, in human body, the relatively weak corrosion resistance of the implants in the body and their inappropriate compatibility has resulted in a great challenge in the application of metallic alloys.
Therefore, Iranian researchers studied a type of composite nanocoating to obtain modified properties of biomaterials to be used in human body.
when the amount of diopside added to the base of hydroxyapatite increases up to 30 weight percent, the size of final composite grain and its size distribution significantly decreases after two steps of sintering process.
because the optimum conditions for applying nanocomposite coating through electrophoretic method on metals are obtained at low particle size distributions s
X-ray crystallography and cryo-electron microscopy to discover the tiny structural details of biomolecules. All these methods,
The synthesis of these fabrics will open new windows to the production of composites with conventional and innovative applications.
The researchers believe their new method is compatible with roll-to-roll manufacturing--an existing method for creating devices in bulk using a roll of flexible plastic and a processing machine.
industrial-quality metal deposited on polymer sheets. First, an electronic mechanical cutter is used to form patterns on the metal-polymer sheets.
Second, after removing excessive areas, the electronics are printed onto any polymer adhesives, including temporary tattoo films.
The cutter is programmable so the size of the patch and pattern can be customized easily.
some of the atoms in the anode--an electrically conductive metal like lithium--become ions that then travel to the cathode,
#Graphene teams up with two-dimensional crystals for faster data communications Ultra-fast detection of light lies at the heart of optical communication systems nowadays.
the research group led by Prof at ICFO Frank Koppens has shown that a two-dimensional crystal, combined with graphene,
but related two-dimensional crystals were still lagging very much behind. In our work we show that by teaming up these two materials,
and magnetic materials interact with each other due to their opposite magnetic ordering direction of magnetization: in magnetic layers storages the magnetic field tends to arrange spins in one direction,
"made of nanolayers of ferromagnetic material, superconductor and other metals. By changing the direction of magnetization it is possible to control the current in superconductor.
and Zhitomirsky, a materials science and engineering professor, demonstrates an improved three-dimensional energy storage device constructed by trapping functional nanoparticles within the walls of a nanocellulose foam.
and transition metal dichalcogenides,"said Awschalom.""It's not just that it's faster and easier.
#Single atom alloy platinum-copper catalysts cut costs, boost green technology: New generation of catalysts demonstrated for selective hydrogenation of butadiene Abstract:
for example in polymer electrolyte membrane (PEM) fuel cells, which are the leading contenders for small-scale and mobile power generation not based on batteries or combustion engines.
in order to facilitate downstream polymer production. The current industrial catalyst for butadiene hydrogenation uses palladium and silver.
while a relatively cheap metal, is not nearly as catalytically powerful as platinum, noted Professor of Chemistry Charles Sykes, Ph d.,one of the senior authors on the paper."
"The researchers first conducted surface science experiments to study precisely how platinum and copper metals mix."
"We were excited to find that the platinum metal dissolved in copper, just like sugar in hot coffee, all the way down to single atoms.
We call such materials single atom alloys, "said Sykes. The Tufts chemists used a specialized low temperature scanning tunneling microscope to visualize the single platinum atoms and their interaction with hydrogen."
such as platinum-copper single atom alloy nanoparticles supported on an alumina substrate, and then tested them under industrial pressure and temperatures."
We believe this approach is also applicable to other precious metals if added as minority components in copper."
In the early 2000s, Maria's group had pioneered the single-atom approach for metals anchored on oxide supports as the exclusive active sites for the water-gas shift reaction to upgrade hydrogen streams for fuel cell use.
Together we embarked on a new direction involving single atom alloys as catalysts for selective hydrogenation reactions.
"Sykes and Flytzani-Stephanopoulos have used this approach to design a variety of single atom alloy catalysts that have,
and properties of single atom alloy surfaces and then applied this knowledge to develop a working catalyst.
#Dielectric film has refractive index close to air The refractive indices of naturally occurring materials are limited, and there exists an index gap between indices of air and available solid materials.
Here we demonstrate a class of ordered nanolattice materials consisting of periodic thin-shell structures with near-unity refractive index and high stiffness.
these ordered nanostructured material have reduced optical scattering and improved mechanical stability compared to existing randomly porous materials.
The demonstrated low-index, low-scattering, and high-stiffness materials can serve as high-quality optical films in multilayer photonic structures, waveguides, resonators,
At issue is called something refractive index, which measures how much light bends when it moves through a substance.
Air, for example, has a refractive index of 1, while water has a refractive index of 1. 33
-which is why a straw appears to bend when you put it in a glass of water.
with some components having a high refractive index and others have a low one. The higher the contrast between those materials
Air has the lowest refractive index, but it isn't mechanically stable. And the lowest refractive index found in solid,
naturally occurring materials is 1. 39. But now researchers have developed a film made of aluminum oxide that has a refractive index as low as 1. 025 but that is mechanically stiff."
"By manipulating the structure of the aluminum oxide, which is dielectric, we've improved both its optical and mechanical properties,
which gives it a more mechanically robust structure without impairing the refractive index, "says Xu Zhang,
The researchers make the film by first using a nanolithography developed in Chang's lab to create highly-ordered pores in a polymer substrate.
That porous polymer then serves as a template, which the researchers coats with a thin layer of aluminum oxide using atomic layer deposition.
The polymer is burned then off leaving behind a three-dimensional aluminum oxide coating.""We are able to control the thickness of the aluminum oxide,
"Using zinc oxide in the same process, we can create a thicker coating. And the thickness of the coating controls
and allows us to design the refractive index of the film.""Regardless of the how thick the coating is,
usually a transition metal oxide. If a voltage is applied then, the ohmic resistance of the storage cell changes.
According to the researchers, the aim of the research was to prepare an injectable paste made of bioglass and sodium alginate polymer with biocompatibility properties.
Results of the research have been published in Journal of the Australian Ceramics Society vol. 51, issue 2, 2015, pp. 99-108 8
This change in reflectivity, in turn, switches how nearby erbium ions emit light. As the VO2 changes phase, the erbium emissions go from being generated mostly by magnetic dipole transitions (the rotational torque push
Finding could have implications for high-temperature superconductivity A team of physicists led by Caltech's David Hsieh has discovered an unusual form of matter--not a conventional metal, insulator,
first consider a crystal with electrons moving around throughout its interior. Under certain conditions, it can be energetically favorable for these electrical charges to pile up in a regular,
repeating fashion inside the crystal, forming what is called a charge-ordered phase. The building block of this type of order, namely charge, is simply a scalar quantity--that is,
When spins line up parallel to each other (in a crystal, for example), they form a ferromagnet--the type of magnet you might use on your refrigerator
The Hsieh group's experiment exploited the fact that changes in the symmetry of a crystal will affect the strength of each harmonic differently.
Since the emergence of multipolar ordering changes the symmetry of the crystal in a very specific way--a way that can be largely invisible to conventional probes--their idea was that the optical harmonic response of a crystal could serve as a fingerprint of multipolar order."
"We found that light reflected at the second harmonic frequency revealed a set of symmetries completely different from those of the known crystal structure,
of metal-organic frameworks (MOFS)- sponge-like 3d crystals with an extraordinarily large internal surface area-that feature flexible gas-adsorbing pores.
a chemist with Berkeley Lab's Materials sciences Division and the University of California (UC) Berkeley who is leading this research."
"Long is the corresponding author of a Nature paper that describes this work entitled,"Methane storage in flexible metal-organic frameworks with intrinsic thermal management."
because the gas must force its way into the MOF crystal structure, opening and expanding the pores.
"In addition, Long says, the step in the adsorption isotherm is associated with a structural phase change in the MOF crystal that reduces the amount of heat released upon filling the tank,
The synthesized magnetic composite is separated from the solution phase in the presence of a magnetic field in a short time through this method.
Results showed that the synthesized composite can be used as an effective sorbent to purify water contaminated by fluoride due to its simple and quick separation, high efficiency and the lack of the creation of secondary pollution in the solution.
The composite can be reused even after five times of application and it can be recycled only by using acidic solution.
#New metal-organic framework material captures carbon at half the energy cost UC Berkeley chemists have made a major leap forward in carbon-capture technology with a material that can
Diamine-Appended Metal-Organic Frameworks The diamine-appended metal-organic framework before and after binding of carbon dioxide.
MOFS are composites of metals--in this case magnesium or manganese--with organic compounds that, together, form a porous structure with microscopic, parallel channels.
Several years ago, Long and his lab colleagues developed a way to attach amines to the metals in an MOF to produce pores of sufficient diameter to allow CO2 to penetrate rapidly into the material.
The pressure at which CO2 binds to the amines can be adjusted by changing the metal in the MOF.
Accion propellant is a liquid salt material, similar in structure to common table salt, which can be made in large quantities.
one that would create designer colors without the use of chemical dyes and pigments. Rather than controlling the chemical composition of a material,
Its flexibility was imparted by embedding the silicon bars into a flexible layer of silicone. As the silicone was bent
or flexed, the period of the grating spacings responded in kind. The semiconductor material also allowed the team to create a skin that was incredibly thin, perfectly flat,
Additionally, ZDDP does not work as well on the lightweight engine materials eyed as potential replacements for steels."
and quickly wear down due to very high local stresses through direct steel-on-steel contacts. The resulting debris can further increase the friction between the surfaces
"The film that grows is not as stiff as the steel. When you push on a stiff surface,
The team demonstrated efficient optical coupling of an array of silicon waveguides to a substrate containing an array of polymer waveguides.
The significant size difference between the silicon waveguides and the polymer waveguides originally presented a major challenge.
The researchers overcame this obstacle by gradually tapering the silicon waveguide, leading to an efficient transfer of the optical signal to the polymer waveguide.
"Mirkin is the George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences and professor of medicine, chemical and biological engineering, biomedical engineering and materials science and engineering.
while also creating new opportunities for graduate students to use the technique for research in materials science and drug delivery at UNC and NCSU.
including elastomers, silicones, nylon-like materials, ceramics and biodegradable materials. The technique itself provides a blueprint for synthesizing novel materials that can further research in materials science.
Rima Janusziewicz and Ashley R. Johnson, graduate students in Desimone's academic lab, are co-authors on the paper
and inhibiting stimulated Brillouin scattering in photonic integrated circuits")."from left: Professor Benjamin Eggleton, Thomas Bttner and Moritz Merklein, researchers from CUDOS at the University of Sydney with the chalcogenide photonic chip.
This nonlinear scattering process can cause signal distortions in fibre communications and signal processing applications and is well known to limit the capacity of optical fiber communications networks.
"Now Gorodetsky has fabricated reflectin films on conformable polymer substrates, effectively sticky tape one might find in any household.
In the journal, ACS Nano("Protease-Mediated Release of Chemotherapeutics from Mesoporous Silica Nanoparticles to ex Vivo Human and Mouse Lung Tumors"),the scientists reported that this approach led to a significant increase
#Artificial hand able to respond sensitively thanks to muscles made from smart metal wires Engineers at Saarland University have taken a leaf out of natures book by equipping an artificial hand with muscles made from shape-memory wire.
and the Center for Mechatronics and Automation Technology (Zema) is using a new technology based on the shape memory properties of nickel-titanium alloy.
Shape-memory alloy (SMA) wires offer significant advantages over other techniques, says Stefan Seelecke. Up until now, artificial hands,
but have the tensile strength of a thick wire. The bundle can rapidly contract and relax while exerting a high tensile force,
the crystal structure reverts back to its austenitic phase, which causes the material to cool down and further absorb heat from its surroundings.
The team's work is the first demonstration that shows elastocaloric materials such as a nickel-titanium (Ni-Ti) alloy can be loaded cyclically
Tuek and colleagues also stabilized the Ni-Ti alloy to ensure a reproducible effect, which is crucial for practical applications,
and created a uniform elastocaloric effect for the alloy. While heat pumps, air conditioners and refrigerators are most likely to benefit from elastocaloric technology,
than a sensor made with the most advanced man-made water-absorbing polymers. There was also better sensitivity in extreme low-pressure, low-humidity situations."
Today reverse-osmosis filters are typically polymers. A filter is thin and resides on a support.
A porous graphene membrane could be more permeable than a polymer membrane, so separated water would drive faster through the membrane under the same conditions, the scientists reasoned."
The researchers transferred the graphene membrane to a silicon nitride support with a micrometer-sized hole.
The silicon nitride chip held the graphene membrane in place while water flowed through it from one chamber to the other.
the researchers relied on the Center for Nanophase Materials sciences (CNMS), a DOE Office of Science User Facility at ORNL.
There has been considerable recent work on using magnetite to clean up toxic metals. For example, magnetite can reduce the toxic form of chromium, chromium VI, to the less toxic chromium (III),
"Aydin and his team tackled this problem by combining nanotechnology, materials science, and plasmonics, the study of the interactions between light and metal.
Sefaatiin Tongay, assistant professor of materials science and engineering at Arizona State university, provided the large-area monolayer Mos2 material used in the study.
In an experiment, recently published in Science("Probing Johnson noise and ballistic transport in normal metals with a single-spin qubit),
thus electrons travel dont travel very far--roughly 10 nanometers or less--before scattering off an obstacle.
In contrast, a single crystal is uniform at these length scales and electrons can travel over 100 times farther.
and corresponding magnetic field noise from the single silver crystal is a departure from so-called Ohmic predictions of the polycrystalline case,
as well as metrology for commercial materials science e
#Extremely sensitive temperature sensor developed with plant nanobionic materials Humans have been inspired by nature since the beginning of time.
#Soft, energy-efficient robotic wings Dielectric elastomers are novel materials for making actuators or motors with soft and lightweight properties that can undergo large active deformations with high-energy conversion efficiencies.
This has made dielectric elastomers popular for creating devices such as robotic hands, soft robots, tunable lenses and pneumatic valves--and possibly flapping robotic wings.
Reporting this week in the journal Applied Physics Letters("Phenomena of nonlinear oscillation and special resonance of a dielectric elastomer minimum energy structure rotary joint"),researchers from the Harbin Institute of technology in Weihai, China
Los angeles (UCLA), have discovered a new resonance phenomenon in a dielectric elastomer rotary joint that can make the artificial joint bend up and down,
Jianwen Zhao/Harbin Institute of technology in Weihai, University of California-Los angeles)" The dielectric elastomer is a kind of electro-active polymer that can deform
He said that most studies on dielectric elastomers are using a static or stable voltage to stimulate the joint motion,
"Zhao said this new phenomenon makes the dielectric elastomer joint a good candidate for creating a soft and lightweight flapping wing for robotic birds,
which would be more efficient than bird wings based on electrical motors due to the higher energy conversion efficiency (60 to 90 percent) of the dielectric elastomer.
Dielectric elastomers, due to their soft and lightweight inherent properties and superior electromechanical performances, are considered as a kind of material close to human muscles
Made by sandwiching a soft insulating elastomer film between two compliant electrodes, dielectric elastomers can be squeezed
and expanded in a plane when a voltage is applied between electrodes. In contrast to actuators based on rigid materials such as silicon, dielectric elastomers can reach a very large extent of stretch, often exceeding 100 percent elongation while not breaking,
enabling new possibilities in many fields including soft robotics, tunable optics, and cell manipulation. The dielectric elastomer actuator Zhao used is called a"dielectric elastomer minimum-energy structure"
which is composed of a thin elastic frame and pre-stretched dielectric elastomer films, Zhao said. After adhering the pre-stretched film to the thin elastic frame,
the restoring force of the dielectric elastomer film bends the elastic frame, balancing at a minimum energy state.
When applying kilovolts of low-current electricity on the dielectric elastomer, the frame flattens out and the bending angle decreases.
To restrict frame bending to only one axis, two stiffening frames are mounted to the primary frame as rigid nonbending edges,
which makes dielectric elastomer minimum-energy structures a useful structure for fabricating soft devices, Zhao said.
After experimenting with various parameters such as voltage values, frequencies and the joint mass in the dielectric elastomer joint system,
Also, since dielectric elastomers feature high energy density (seventy times higher than conventional electromagnetic actuators) and high-energy conversion efficiency (60 to 90 percent), they could be good candidates for making energy-efficient devices,
The researchers'next step is to improve the function of the dielectric elastomer rotary joint and refine the fabrication technique to make a real flapping wing g
In actual alloy nanowires though, atoms of the same element might cluster together to form short sections composed of the same elements.
"Their results suggest that heat conduction in a nanowire does not just depend on the relative concentrations of the alloy atoms and the difference in their masses;
high-frequency phonons could travel much further than the average length of the ordered regions in the alloy.
In contrast, a random distribution of alloy atoms resulted in a higher resistance over triple that of the ordered case for a 2. 5-micrometer-long wire.
If this disorder can be realized in real composite materials then we could tailor the thermal conductivity of the system,
For instance, the surface roughening of nanowires is known to reduce the thermal conductivity contribution of high-frequency phonons
The researchers hope their model will help scientists design composite materials with low thermal conductivity. One attractive application is thermoelectric devices,
a low thermal conductivity is desirable for optimal performance e
#Smart micelles for marine environments martmaterials that alter their structure in response to specific, controllable stimuli have applications in various fields, from biomedical science to the oil industry.
when moved from water to an electrolyte solution, such as salt water("Dual hydrophilic and salt responsive schizophrenic block copolymers synthesis and study of self-assembly behavior").
Materials composed of segments of two different monomers, each with different characteristics, are known as block copolymers.
Vivek Vasantha at A*STAR Institute of Chemical and Engineering sciences together with scientists from across Singapore under the Innovative Marine Antifouling Solutions (IMAS) program developed a new block copolymer that can self-assemble into spherical micelle structures in
which one monomer forms the core and the other forms the outer shell. The monomers are the hydrophilic poly (ethylene glycol
or PEG, which mixes well with water, and the halophilic polysulfabetaine (PSB), which has a preference for salt solution. e created salt-responsive block copolymers that self-assemble in water to form either onventionalor nversemicelles, states Vasantha.
The conventional micelles form in deionized water and have a core of halophilic PSB with a hydrophilic PEG shell.
However, the team showed that the micelles reassemble themselves when immersed in salt solution; PEG formed the core,
The researchers mixed the block copolymers with primer to create a nontoxic coating to replace traditional antifouling paint.
Overtext Web Module V3.0 Alpha
Copyright Semantic-Knowledge, 1994-2011