#New 2d transistor material made using precision lasers Molybdenum ditelluride (Mote2) is a crystalline compound that
if pure enough can be used as a transistor. Its molecular structure is an atomic sandwich made up of one molybdenum atom for every two tellurium atoms HY1.
but until last year it had never been made in a pure enough form to be suitable for electronics.
Last year a multi-discipline research team led by South korea Institute for Basic Science (IBS) Center for Integrated Nanostructure Physics at Sungkyunkwan University (SKKU) director Young Hee
and it was seen by some as a black sheep of the transition metal dichalcogenides (TMD) family and purposefully ignored.
and have an electrical property called a band gap, which makes them ideal for making electrical components,
especially transistors. A TMD crystal follows an MX2 format: there is one transition metal, represented by M m can be Tungsten, Molybdenum, etc.)
and two chalcogenides, the X2 (Sulfur, Selenium, or Tellurium. These atoms form a thin, molecular sandwich with the one metal and two chalcogenides,
and depending on their fabrication method can exist in several slightly different shaped atomic arrangements. The overwhelming majority of microchips that exist in electronics now are made from silicon,
and they work extremely well. However, as devices get smaller there is an increasing demand to shrink the size of the logic chips that make those devices work.
As the chips approach single or several atom thickness, (commonly referred to as 2-dimensional),
silicon no longer works as well as it does in a larger, 3-dimensional (3d) scale. As the scale approaches 2 dimensions (2d), the band gap of silicon changes (higher band gap than that of its 3d form)
and the contact points with metal connections on silicon are no longer smooth enough to be used efficiently in electrical circuits.
This is the perfect opportunity to employ new, exotic TMD materials. The IBS research team was able to exploit the two versions of Mote2
and make one 2d crystal that was composed of the semiconducting 2h-Mote2 and the metallic 1t'-Mote2.
This configuration is superior to using silicon as well as other 2d semiconductor because the boundary where the semiconducting (2h) and metallic (1t')Mote2 meet to have called
what am ohmic homojunction. This is a connection that forms at the boundary between two different structural phases in a single material.
Despite one Mote2 state being a semiconductor and one being metallic, the team was able to create an ohmic homojunction between them,
making an extremely efficient connection. To do this, the team started with a piece of their pure 2h-Mote2
With this method, the team was able to create a 2d transistor that utilized an amalgamation of both the semiconducting properties of the 2h-Mote2 material as well as the high conductivity of the 1t'-Mote2("Phase patterning for ohmic homojunction contact
By using only one material in the device channel and the metal-semiconductor junction, it is more energy efficient
metal electrodes can be applied to it directly, saving any additional work of finding a way to attach metal leads.
This new fabrication technique is a hyper-efficient way of utilizing the available Mote2 without any wasted or extraneous parts.
Professor Heejun Yang of SKKU said, here are many candidates for 2d semiconductors, but Mote2 has a band gap of around 1 ev
which is similar to silicon band gap and it allows an ohmic homojunction at the semiconductor-metal junctions.
This means that Mote2 can replace silicon without much change in the current voltage configurations used with today silicon technologies.
The dual-phase Mote2 transistor looks promising for use in new electronic devices as demand for components increases for materials that are small, light and extremely energy efficient n
#Using lasers to tailor the properties of graphene Carbon nanomaterials display extraordinary physical properties, outstanding among any other substance available,
and Graphene has grown as the most promising material for brand-new electronic circuitry, sensors and optical communications devices.
Graphene is a single atomic-thick sheet of honeycomb carbon lattice, with unique electronic and optical properties,
which bring a new era of fast, reliable, low power communication and information processing. But two problems hinder graphene's uptake in real world electronics.
There is no large-scale technology to control the properties, and the traditional technology used for silicon-based processors (solid state) is not suitable for graphene processing (molecular material).
The researchers from Technological Center AIMEN explore the use of ultrafast lasers as tool for graphene processing.
The laser beam can be focused precisely, used to tailor the properties of graphene films in finely defined areas,
producing nanodevices with minimal footprint and maximum efficiency. As recently published in AIP Applied Physics Letters("Patterned graphene ablation and two-photon functionalization by picosecond laser pulses in ambient conditions),
"the work of AIMEN researches demonstrated laser based large scale patterning of graphene at high speed and resolution, opening new possibilities for device making.
the work demonstrated the control of the thermal and chemical processes by adjusting laser beam characteristics. For low energy inputs, multiphoton absorption plays a major role, inducing chemical reactions between carbon
as well as tests in real device application for future electronics. About AIMEN Located in Northwestern Spain
AIMEN Technology Centre, has over 45 years experience in materials science and technology, and industrial R&d in a wide spectrum of applications, from transport to medicine.
The Laser Applications Centre of AIMEN is devoted to applied research in the field of laser materials processing,
being the largest Spanish laser center in terms of research personnel and investment. The work leading to these results was held within the European FAIERA project, funded by the European union Seventh Framework Programme (GA 316161), under the Research Potential initiative REGPOT in the Capacities Programme a
#Integration of quantum dots and photonic crystals produce brighter, more efficient light Recently, quantum dots (QDS) ano-sized semiconductor particles that produce bright, sharp,
color lightave moved from the research lab into commercial products like high-end TVS, e readers, laptops,
and even some LED lighting. However, QDS are expensive to make so there a push to improve their performance and efficiency,
A team of researchers from the University of Illinois at Urbana-Champaign has produced recently some promising results toward that goal,
developing a new method to extract more efficient and polarized light from quantum dots (QDS) over a large-scale area.
and photonic crystal technology, could lead to brighter and more efficient mobile phone, tablet, and computer displays, as well as enhanced LED lighting.
With funding from the Dow chemical Company, the research team--led by Brian Cunningham (ECE), Ralph Nuzzo (chemistry),
and Andrew Alleyne (Mechse)--embedded QDS in novel polymer materials that retain strong quantum efficiency.
They then used electrohydrodynamic jet (e-jet) printing technology to precisely print the QD-embedded polymers onto photonic crystal structures.
an ECE graduate student and the lead author of the research reported this week in Applied Physics Letters("Polarized quantum dot emission in electrohydrodynamic jet printed photonic crystals),
and more efficient displays. ince screens consume large amounts of energy in devices like laptops, phones,
and tablets, our approach could have a huge impact on energy consumption and battery life, she noted. f you start with polarized light,
See explained. f you put the photonic crystal-enhanced quantum dot into a device like a phone or computer,
then the battery will last much longer because the display would only draw half as much power as conventional displays.
To demonstrate the technology, See fabricated a novel 1mm device (aka Robot Man) made of yellow photonic crystal-enhanced QDS.
The device is made of thousands of quantum dots, each measuring about six nanometers. e made a tiny device,
but the process can easily be scaled up to large flexible plastic sheets, See said. e make one expensive astermolding template that must be designed very precisely,
a process that stops the greenhouse gas before it escapes from chimneys and power plants into the atmosphere and instead turns it into a useful product.
One possible end product is methanol, a liquid fuel and the focus of a recent study conducted at the U s. Department of energy's (DOE) Argonne National Laboratory("Carbon dioxide Conversion to Methanol over Size-Selected Cu4 Clusters at Low pressures").
and convert carbon dioxide in a way that ultimately saves energy. They call it a copper tetramer. It consists of small clusters of four copper atoms each, supported on a thin film of aluminum oxide.
These catalysts work by binding to carbon dioxide molecules, orienting them in a way that is ideal for chemical reactions.
The structure of the copper tetramer is such that most of its binding sites are open
The current industrial process to reduce carbon dioxide to methanol uses a catalyst of copper, zinc oxide and aluminum oxide.
A number of its binding sites are occupied merely in holding the compound together, which limits how many atoms can catch
"To compensate for a catalyst with fewer binding sites, the current method of reduction creates high-pressure conditions to facilitate stronger bonds with carbon dioxide molecules.
But compressing gas into a high-pressure mixture takes a lot of energy. The benefit of enhanced binding is that the new catalyst requires lower pressure
and less energy to produce the same amount of methanol. Carbon dioxide emissions are an ongoing environmental problem,
and according to the authors, it's important that research identifies optimal ways to deal with the waste."
"We're interested in finding new catalytic reactions that will be more efficient than the current catalysts,
especially in terms of saving energy,"said Larry Curtiss, an Argonne Distinguished Fellow who co-authored this paper.
Copper tetramers could allow us to capture and convert carbon dioxide on a larger scale--reducing an environmental threat
and creating a useful product like methanol that can be transported and burned for fuel. Of course the catalyst still has a long journey ahead from the lab to industry.
And while the scientists needed only nanograms of the material for this study, that number would have to be multiplied dramatically for industrial purposes.
Meanwhile, the researchers are interested in searching for other catalysts that might even outperform their copper tetramer.
These catalysts can be varied in size, composition and support material, which results in a list of more than 2, 000 potential combinations, Vajda said.
and then test the catalysts that seem most promising.""We haven't yet found a catalyst better than the copper tetramer,
"With global warming becoming a bigger burden, it's pressing that we keep trying to turn carbon dioxide emissions back into something useful."
"For this research, the team used the Center for Nanoscale Materials as well as beamline 12-ID-C of the Advanced Photon Source, both DOE Office of Science User Facilities.
Curtiss said the Advanced Photon Source allowed the scientists to observe ultralow loadings of their small clusters, down to a few nanograms,
which was a critical piece of this investigation n
#Super-small needle technology for the brain Microscale needle-electrode array technology has enhanced brain science and engineering applications, such as electrophysiological studies, drug and chemical delivery systems, and optogenetics.
However, one challenge is reducing the tissue/neuron damage associated with needle penetration, particularly for chronic insert experiment and future medical applications.
A solution strategy is to use microscale-diameter needles (e g.,<,<5 m) with flexible properties.
and other biological tissues because of needle buckling or fracturing on penetration. high-aspect-ratio microneedles penetrating brain tissue A research team in the Department of Electrical and Electronic Information Engineering
and the Electronics-Inspired Interdisciplinary Research Institute (EIIRIS) at Toyohashi University of Technology has developed a methodology to temporarily enhance the stiffness of a long, high-aspect-ratio flexible microneedle (e g.,<
which dissolves upon contact with biological tissue. Silk fibroin is used as the dissolvable film because it has high biocompatibility,
and is known a biomaterial used in implantable devices.""We investigated preparation of a silk base scaffold for a microneedle, quantitatively analyzed needle stiffness,
and evaluated the penetration capability by using mouse brains in vitro/in vivo. In addition, as an actual needle application, we demonstrated fluorescenctce particle depth injection into the brain in vivo,
and confirm that by observing fluorescenctce confocal microscope"explained the first author, master's degree student Satoshi Yagi,
and co-author Phd candidate Shota Yamagiwa. The leader of the research team, Associate professor Takeshi Kawano said:"
"Preparation of the dissolvable base scaffold is very simple, but this methodology promises powerful tissue penetrations using numerous high-aspect-ratio flexible microneedles,
including recording/stimulation electrodes, glass pipettes, and optogenetic fibers.""He added:""This has the potential to reduce invasiveness drastically
#Silicon nanodevice solves overheating problem in lab analysis technique Scientists from the London Centre for Nanotechnology (LCN),
Imperial College London and the University of Buenos aires have published the results of a study testing a silicon nanodevice in the journal Nature Communications("Non-plasmonic nanoantennas for surface enhanced spectroscopies with ultra-low
"This silicon nanodevice can funnel laser light to a tightly focused spot and probe biological molecules to explore their potential use as new drugs.
The device has the potential to replace gold nanodevices used in current analytical techniques, where the metal elements can become heated to temperatures of 120 degrees celsius.
This quickly damages delicate biological samples and potentially melts the equipment. The innovation is expected to expand the ability of researchers to investigate potential new drugs more rapidly and accurately,
and safely at normal room temperatures. Future equipment based on the silicon devices could also be designed for a variety of uses
including investigating individual biochemical reactions and detecting molecules such as contaminants or explosives at extremely low concentrations.
focusing their energy into a tight spot. When the material is a metal, that spot also becomes very hot.
The scientists have shown that the same effect can be achieved using their new silicon device, without the associated temperature increase and its unfortunate consequences.
or the development of silicon computing chips that process data communicated by photons of light instead of electricity.
Common laboratory analytical techniques such as Raman and fluorescence spectroscopy determine the properties of biological molecules,
and structure,"said Dr Emiliano Cortes, from the Department of physics at Imperial College London, one of the authors of the study."
"Amongst other things, this information can help to predict how the molecules might interact with biochemical processes in living cells,
"However the characteristics of metals that make them good at conducting electricity also lead to the undesirable heating effect,
They also conduct electricity well, so can also pass electronic information back to the equipment."
"The cloud of free-moving electrons around a metal that carries an electrical current can also absorb passing photons.
The scientists experimented with silicon structures used in computer chips that power computers, tablets and mobile phones,
which can conduct electricity but their electrons absorb fewer passing photons.""While this extremely localised
such as in biochemical analysis,"said Dr Cortes. The discovery opens up the possibility for new equipment that can track individual biochemical reactions in over a period of time,
#Scientists make tantalum oxide practical for high-density devices Scientists at Rice university have created a solid-state memory technology that allows for high-density storage with a minimum incidence of computer errors.
The memories are based on tantalum oxide, a common insulator in electronics. Applying voltage to a 250-nanometer-thick sandwich of graphene, tantalum,
nanoporous tantalum oxide and platinum creates addressable bits where the layers meet. Control voltages that shift oxygen ions
The discovery by the Rice lab of chemist James Tour could allow for crossbar array memories that store up to 162 gigabits
Eight bits equal one byte; a 162-gigabit unit would store about 20 gigabytes of information.
A schematic shows the layered structure of tantalum oxide, multilayer graphene and platinum used for a new type of memory developed at Rice university.
The memory device overcomes crosstalk problems that cause read errors in other devices. Image: Tour Group/Rice university) Details appear online in the American Chemical Society journal Nano Letters("Three-dimensional Networked Nanoporous Ta2o5x Memory System for Ultrahigh Density Storage".
"Like the Tour lab's previous discovery of silicon oxide memories, the new devices require only two electrodes per circuit,
"But this is a new way to make ultradense, nonvolatile computer memory, "Tour said. Nonvolatile memories hold their data even
when the power is off, unlike volatile random-access computer memories that lose their contents
when the machine is shut down. Modern memory chips have many requirements: They have to read and write data at high speed
and hold as much as possible. They must also be durable and show good retention of that data
while using minimal power. Tour said Rice's new design, which requires 100 times less energy than present devices,
has the potential to hit all the marks.""This tantalum memory is based on two-terminal systems,
so it's all set for 3-D memory stacks, "he said.""And it doesn't even need diodes
or selectors, making it one of the easiest ultradense memories to construct. This will be a real competitor for the growing memory demands in high-definition video storage and server arrays."
"The layered structure consists of tantalum, nanoporous tantalum oxide and multilayer graphene between two platinum electrodes.
In making the material, the researchers found the tantalum oxide gradually loses oxygen ions, changing from an oxygen-rich, nanoporous semiconductor at the top to oxygen-poor at the bottom.
Where the oxygen disappears completely, it becomes pure tantalum, a metal. The researchers determined three related factors give the memories their unique switching ability.
First, the control voltage mediates how electrons pass through a boundary that can flip from an ohmic (current flows in both directions) to a Schottky (current flows one way) contact and back.
Third, the flow of current draws oxygen ions from the tantalum oxide nanopores and stabilizes them.
These negatively charged ions produce an electric field that effectively serves as a diode to hinder error-causing crosstalk.
and a way to control the size of the nanopores s
#Bioengineers identify the key genes and functions for sustaining microbial life (Nanowerk News) A new study led by bioengineers at the University of California,
San diego defines the core set of genes and functions that a bacterial cell needs to sustain life.
The research, which answers the fundamental question of what minimum set of functions bacterial cells require to survive,
could lead to new cell engineering approaches for E coli and other microorganisms, the researchers said.
2015("Systems biology definition of the core proteome of metabolism and expression is consistent with high-throughput data".
"This core set of genes is"the smallest common denominator that microbes need to have to become functional,
"said Bernhard Palsson, the Galetti Professor of Bioengineering at UC San diego and corresponding author on the paper."
Consider, for example, the genetic engineering of microbes to make value-added chemicals. This engineering process is done typically by making changes to the genetic makeup of a cell,
which can end up toying with the cell's core genes and functions, resulting in a"sick"cell.
Rather than risk compromising the cell's core genes and functions, a new engineering approach could involve building the cell starting with the core set
and adding on the extra desired functions, like chemical production. The PNAS paper presents the minimum core components that are absolutely necessary to include in the blueprints of an engineered cell."
"By defining the vital set of genes and functions that need to always be present in a cell to sustain life,
"said Laurence Yang, a postdoctoral researcher in Palsson's Systems Biology Research Group at UC San diego and a co-first author of the paper.
The work, led by Palsson's research group at UC San diego Jacobs School of engineering, is a collaborative effort with numerical and statistical experts from Stanford university.
Defining the core set of genes and functions for cellular life In this study the researchers defined the core set of genes
and functions as the"paleome,"referring to the ancestral genes and proteins that are at the heart of sustaining life for microbial cells."
"Other approaches have tried to define the paleome by comparing genome sequences and finding the gene portfolio that seemed to be similar in all of these sequences.
This just defines the minimal genome. Our definition of the paleome takes a more comprehensive approach.
It is a systems-biology-based definition that takes into account not just the minimum set of genes,
but also the minimum set of functions, reactions and processes needed to build a cell, "said Palsson.
The team's approach to define the paleome is based on a genome-scale computational model for cellular growth in E coli.
and gene expression processes in the cell. Using this model the researchers simulated the growth of a well-studied strain of E coli across 333 different growth conditions.
which set of genes was expressed consistently throughout all the different growth environments and used this set to construct the paleome.
"Our paleome definition is representative of core function not only in the well-studied strain of E coli,
We are hoping to use this paleome as a starter kit to rapidly build a new generation of genome-scale cellular growth models for other organisms,
In this case, we have used large amounts of experimental data and integrated them in the form of a computational model to arrive at our systems biology definition of the paleome
#Engineering a permanent solution to genetic diseases (Nanowerk News) In his mind, Basil Hubbard can already picture a new world of therapeutic treatments for millions of patients just over the horizon.
Its a future in which diseases like muscular dystrophy, cystic fibrosis and many others are treated permanently through the science of genome engineering.
Thanks to his latest work, Hubbard is bringing that future closer to reality. Basil Hubbard Hubbards research, published in the journal Nature Methods("Continuous directed evolution of DNA BINDING-PROTEINS proteins to improve TALEN specificity),
"demonstrates a new technology advancing the field of genome engineering. The method significantly improves the ability of scientists to target specific faulty genes
and then edit them, replacing the damaged genetic code with healthy DNA. There is a trend in the scientific community to develop therapeutics in a more rational fashion,
rather than just relying on traditional chemical screens, says Hubbard, an assistant professor of pharmacology in the University of Albertas Faculty of medicine & Dentistry.
Were moving towards a very logical type of treatment for genetic diseases, where we can actually say,
Your disease is caused by a mutation in gene X, and were going to correct this mutation to treat it.
In theory, genome engineering will eventually allow us to permanently cure genetic diseases by editing the specific faulty gene (s). Revolutionizing health care Genome engineering involves the targeted
specific modification of an organisms genetic information. Much like how a computer programmer edits computer code, scientists could one day replace a persons broken
or unhealthy genes with healthy ones through the use of sequence-specific DNA BINDING PROTEINS attached to DNA-editing tools.
The field has made large strides over the last two decades and may one day revolutionize medical care.
One of the obstacles still to be addressed in the field before it can see widespread use in humans is how to ensure the proteins only affect the specific target genes in need of repair.
With current technologies the proteins bind to and edit the correct genes the vast majority of the time,
but more improvements are needed to ensure off-target genes arent modifieda result that could potentially cause serious health problems itself.
Improving the specificity of DNA BINDING-PROTEINS proteins Through his research, undertaken as a postdoctoral fellow in the lab of David R. Liu at Harvard university,
Hubbard has developed a way to reduce the off-target DNA binding of a class of gene editing proteins known as transcription activator-like effector nucleases (TALENS).
Future applications Currently much of the research in the field of genome engineering is focused on treating monogenic diseasesdiseases that involve a single geneas theyre much easier for researchers to successfully target.
Examples include diseases such as hemophilia sickle cell anemia, muscular dystrophy and cystic fibrosis. While the field is still in its relative infancy,
Hubbard says human clinical trials involving sequence-specific DNA-editing agents are already underway. If successful, he expects the first clinical applications could be seen in the next decade.
He hopes his current work will play a role in helping genome engineering reach its full potential
gene editing could possibly provide a permanent cure for a lot of different diseases, says Hubbard. We still have to overcome many hurdles but
I think this technology definitely has the potential to be transformative in medicine e
#Reflexes for robots (w/video)( Nanowerk News) Deep in the basement of MITS Building 3, a two-legged robot named HERMES is wreaking controlled havoc:
punching through drywall, smashing soda cans, kicking over trash buckets, and karate-chopping boards in half. Its actions,
Just a few feet away, Phd student Joao Ramos stands on a platform, wearing an exoskeleton of wires and motors.
As Ramos mimes punching through a wall, the robot does the same. When the robots fist hits the wall, Ramos feels a jolt at his waist.
By reflex, he leans back against the jolt, causing the robot to rock back, effectively balancing the robot against the force of its punch.
Phd student Joao Ramos demonstrates the Balance Feedback Interface, a system that enables an operator to control the balance and movements of a robot, through an exoskeleton and motorized platform.
while the robot may successfully punch through a wall, it would also fall headlong into that wall.
The interface allows a human to remotely feel the robots shifting weight, and quickly adjust the robots balance by shifting his own weight.
the robot can carry out momentum-driven tasks like punching through walls, or swinging a bat
Ultimately, Ramos and his colleagues envision deploying HERMES to a disaster site, where the robot would explore the area, guided by a human operator from a remote location.
Ramos and his colleagues, including Phd student Albert Wang and Sangbae Kim the Esther and Harold E. Edgerton Center Career development Assistant professor of Mechanical engineering, will present a paper on the interface at the IEEE/RSJ International Conference on Intelligent Robots and Systems in September.
Balance and feedback To give the human operator a sense of the robots balance, the team first looked for a way to measure the robots center of pressure,
a 100-pound biped robot designed by the team, along with the interface, for disaster response.
They outfitted the robots feet with load sensors that measure the force exerted by each foot on the ground.
With computer software, the researchers translated the robots center of pressure to the platforms motors,
The interface works by pushing harder on the operator as the robots center of pressure approaches the edge of the support polygon,
when the hammer would strike. As Wang struck the robot, the platform exerted a similar jolt on Ramos,
In one test, the robot unexpectedly got its arm stuck in the wall. But, because the human was in the loop,
Jonathan Hurst, associate professor of mechanical, industrial, and manufacturing engineering at Oregon State university, says the new balance interface is an intuitive platform for operators,
But perhaps more important than just a way to control a robot in the absence of knowing how to do it autonomously is being able to observe and collect data from the robot.
Given hours of data recording the details of human strategies for balance and pose adjustment,
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