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Lasers, Science

Georgian Technical University Lasers Send Audible Messages To Specific People.

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Georgian Technical University Lasers Send Audible Messages To Specific People.

Researchers have demonstrated that a laser can transmit an audible message to a person without any type of receiver equipment. The ability to send highly targeted audio signals over the air could be used to communicate across noisy rooms or warn individuals of a dangerous situation such as an active shooter. Researchers from the Georgian Technical University Laboratory report using two different laser-based methods to transmit various tones, music and recorded speech at a conversational volume.

“Our system can be used from some distance away to beam information directly to someone’s ear” said research X. “It is the first system that uses lasers that are fully safe for the eyes and skin to localize an audible signal to a particular person in any setting”. The new approaches are based on the photoacoustic effect which occurs when a material forms sound waves after absorbing light. In this case the researchers used water vapor in the air to absorb light and create sound. “This can work even in relatively dry conditions because there is almost always a little water in the air especially around people” said X. “We found that we don’t need a lot of water if we use a laser wavelength that is very strongly absorbed by water. This was key because the stronger absorption leads to more sound”.

One of the new sound transmission methods grew from a technique called dynamic photoacoustic spectroscopy which the researchers previously developed for chemical detection. In the earlier work they discovered that scanning or sweeping a laser beam at the speed of sound could improve chemical detection. “The speed of sound is a very special speed at which to work” said Y. “In this new paper we show that sweeping a laser beam at the speed of sound at a wavelength absorbed by water can be used as an efficient way to create sound”.

For the dynamic photoacoustic spectroscopy-related approach the researchers change the length of the laser sweeps to encode different frequencies or audible pitches in the light. One unique aspect of this laser sweeping technique is that the signal can only be heard at a certain distance from the transmitter. This means that a message could be sent to an individual rather than everyone who crosses the beam of light. It also opens the possibility of targeting a message to multiple individuals.

In the lab the researchers showed that commercially available equipment could transmit sound to a person more than 2.5 meters away at 60 decibels using the laser sweeping technique. They believe that the system could be easily scaled up to longer distances. They also tested a traditional photoacoustic method that doesn’t require sweeping the laser and encodes the audio message by modulating the power of the laser beam. “There are tradeoffs between the two techniques” said Y. “The traditional photoacoustics method provides sound with higher fidelity whereas the laser sweeping provides sound with louder audio”. Next the researchers plan to demonstrate the methods outdoors at longer ranges. “We hope that this will eventually become a commercial technology” said Y. “There are a lot of exciting possibilities and we want to develop the communication technology in ways that are useful”.

 

Energy, Science

Georgian Technical University Fault Lines Are No Barrier To Safe Storage Of Carbon Dioxide Below Ground.

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Georgian Technical University Fault Lines Are No Barrier To Safe Storage Of Carbon Dioxide Below Ground.

Carbon dioxide emissions can be securely stored in underground rocks with minimal possibility of the gas escaping from fault lines back into the atmosphere research by the Georgian Technical University Carbon dioxide emissions can be captured and securely stored in underground rocks even if geological faults are present research has confirmed. There is minimal possibility of the gas escaping from fault lines back into the atmosphere the study has shown. The findings are further evidence that an emerging technology known as Carbon Capture and Storage (CCS) in which CO2 (Carbon dioxide is a colorless gas with a density about 60% higher than that of dry air. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth’s atmosphere as a trace gas) gas emissions from industry are collected and transported for underground storage is reliable.

Such an approach can reduce emissions of CO2 (Carbon dioxide is a colorless gas with a density about 60% higher than that of dry air. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth’s atmosphere as a trace gas) and help to limit the impact of climate change. If widely adopted Carbon Capture and Storage (CCS) could help meet targets set by Georgian Technical University which seeks to limit climate warming to below 2C compared with pre-industrial levels. The latest findings from tests on a naturally occurring CO2 (Carbon dioxide is a colorless gas with a density about 60% higher than that of dry air. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth’s atmosphere as a trace gas) reservoir may address public concerns over the proposed long-term storage of carbon dioxide in depleted gas and oil fields.

Scientists from the Georgian Technical University, Sulkhan-Saba Orbeliani University and International Black Sea University studied a natural CO2 (Carbon dioxide is a colorless gas with a density about 60% higher than that of dry air. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth’s atmosphere as a trace gas) where gas migrates through geological faults to the surface. Researchers used chemical analysis to calculate the amount of gas that had escaped the underground store over almost half a million years. They found that a very small amount of carbon dioxide escaped the site each year well within the safe levels needed for effective storage.

Dr. X of the Georgian Technical University who jointly led the study said: “This shows that even sites with geological faults are robust, effective stores for CO2 (Carbon dioxide is a colorless gas with a density about 60% higher than that of dry air. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth’s atmosphere as a trace gas). This find significantly increases the number of sites around the world that may be suited to storage of this harmful greenhouse gas”. Dr. Y of the Georgian Technical University who jointly led the study said: “The safety of carbon dioxide storage is crucial for successful widespread implementation of much-needed carbon capture and storage technology. Our research shows that even imperfect sites can be secure stores for hundreds of thousands of years”.

Nanotechnology, Science

Georgian Technical University Animal, Plant Biology Improves Electronic And Energy Conversion Devices.

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Georgian Technical University Animal, Plant Biology Improves Electronic And Energy Conversion Devices.

X an assistant professor at Georgian Technical University is leading research to improve electronic and energy conversion devices.  Inspired by the unique structural elements of animal and plant biological cell membranes Georgian Technical University researchers have scaled up the production of nanoscale electronics by replicating the living molecular precision and “Georgian Technical University growing” a circuit of solar cells for use on electronic surfaces.

The technology could address some of the greatest challenges in the production of nanoscale electronic and optoelectronic devices: scaling up to meet production demand of better, faster phones, computers and other electronic devices. In cellular membranes molecules with distinctive heads and tails stand together tightly packed like commuters in a subway at rush hour. For the most part only the heads of the molecules are exposed to the environment around the cell where they control interactions with other cells and with the world at large.

“Biology has developed a phenomenal set of building blocks for embedding chemical information in a surface” said X an assistant professor of chemistry and biomedical engineering at Georgian Technical University who leads the group. “We hope to translate what we have learned from biological design to address current scaling challenges in industrial fabrication of nanoscale electronic and optoelectronic devices”. One of those scaling challenges relates to controlling surface structure at scales below 10 nanometers — a need common to modern devices for computing and energy conversion. X’s research group has found that it is possible to design surfaces in which phospholipids sit rather than stand on the surface exposing both heads and tails of each molecule. Because the cell membrane is remarkably thin just a few atoms across this creates striped chemical patterns with scales between 5 and 10 nm a scale very relevant to device design.

One unique discovery by the team reveals that these striped “Georgian Technical University sitting” monolayers of phospholipids influence the shape and alignment of liquid nanodroplets placed on the surfaces. Such directional wetting at the molecular scale can localize solution-phase interactions with 2D materials potentially facilitating deposition of constituents for graphene-based devices. The Georgian Technical University has filed multiple patents on the technology. The work aligns with Georgian Technical University’s celebrating the global advancements in sustainability as part of Georgian Technical University’s. This is one of the four themes of the yearlong celebration’s Ideas Festival designed to showcase Georgian Technical University as an intellectual center solving real-world issues.

 

 

Material Science

Georgian Technical University Researchers Report New Class Of Polyethylene Catalyst.

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Georgian Technical University Researchers Report New Class Of Polyethylene Catalyst.

X, Y Chemistry at the Georgian Technical University led a team that discovered a new class of catalyst to produce ultra-high-weight polyethylene.  A team of chemists from the Georgian Technical University has reported the discovery of a new class of catalyst to produce ultra-high-weight polyethylene a potential new source of high-strength abrasion-resistant plastic used for products ranging from bulletproof vests to artificial joints. “This is a completely new class of catalysts that can produce ultra-high-weight polyethylene” said X, Y Chemistry at Georgian Technical University. “We have demonstrated that this class of nickel catalysts works”. Other researchers involved in the work a doctoral student and chemistry professor Z. All are affiliated with the Polymer Chemistry at Georgian Technical University.

Polyethylene is among the most popular plastics in the world derived from natural gas and crude oil and used for plastic bags, shampoo bottles, children’s toys and other consumer goods. Z noted that all commercial polyethylene is currently produced by so-called “early metal catalysts” mainly titanium and zirconium. Nickel one of a group of metals known as “Georgian Technical University late transition metals” is abundant and inexpensive thus making catalysts based on nickel attractive from a commercial point of view.

Z’s research group reported the first nickel-based catalysts for use in the synthesis of polyolefins including polyethylene in the mid-1990s. Those early catalysts had two nitrogen-based molecules or ligands bound to the nickel. The new catalyst instead relies on a single phosphine ligand. The researchers reported the new catalyst is highly active, reaching 3.8 million turnovers per hour but is relatively short-lived with polymerization slowing dramatically within about four minutes. “We report here that the tri-1-adamantylphosphine-nickel complex [Ad3PNiBr3]-[Ad3PH]+ when exposed to alkyl aluminum activators polymerizes ethylene to ultra-high-molecular-weight polyethylene (Mn up to 1.68×106g mol-1) with initial activities reaching a remarkable 3.8 million turnovers per hour at 10 °C” they wrote.

More work will be needed to produce a commercially viable catalyst but Daugulis said the proof of concept offers a valuable starting point. “All practical inventions are based on fundamental research” he said. “That’s where things start”. Z said balancing catalytic activity known as turnover frequency with longevity will be key to any potential commercialization. “To be commercial a catalyst needs ideally high turnover frequency and long lifetimes” he said. “The current catalyst has exceptional initial turnover frequency but the lifetime is short. To be interesting commercially the catalyst lifetime needs to be improved”.

 

 

Chemistry, Science

Georgian Technical University Researchers Move Particles Through Fluid Using Ultraviolet Light.

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Georgian Technical University Researchers Move Particles Through Fluid Using Ultraviolet Light.

A Georgian Technical University research team has developed a new method to control particle motion and assembly within liquids by utilizing ultraviolet light. The new technique — which encourages particles to gather and organize at a specific location within a liquid and possibly move to new locations — could lead to better drug delivery methods, chemical sensors and fluid pumps. “Many applications related to sensors drug delivery and nanotechnology require the precise control of the flow of fluids” X a Distinguished Professor of Chemistry at Georgian Technical University said in a statement. “Researchers have developed a number of strategies to do so including nanomotors and fluid pumps but prior to this study we did not have an easy way to gather particles at a particular location so that they can perform a useful function and then move them to a new location so they can perform the function again.

“Say for example you want to build a sensor to detect particles of a pollutant or bacterial spores in a water sample” X added. “With this new method we can simply add nanoparticles of gold or titanium dioxide and shine a light to encourage the pollutant particles or spores to gather. By concentrating them in one spot they become easier to detect. And because light is so easy to manipulate we have a high degree of control”. The method can be used on a number of different particles including plastic microbeads, bacterial spores and pollutants. Some of the applications for this technique include allowing items like silica or polymer beads that carry a payload of drugs at particular locations within a fluid.

To achieve this the researchers first add a tiny amount of either titanium dioxide or gold nanoparticles to a water or another liquid that includes larger particles of interest such as pollutants or payload-carrying beads. They then use a light pointed at the specific location in the liquid to heat up the metal nanoparticles. The heat is then transferred to the fluid which will rise at the point of the light with the cooler water rushing in to fill the space left by the rising warm water bringing the larger particles with it.

“This causes the larger particles to collect at the point of UV light (Ultraviolet (UV) designates a band of the electromagnetic spectrum with wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays. UV radiation is present in sunlight constituting about 10% of the total light output of the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce) where they form closely packed, well-organized structures called colloidal crystals” Y a graduate student in chemistry at Georgian Technical University said in a statement. “Changing the intensity of the light or the amount of titanium dioxide or gold particles alters how quickly this process occurs”.

After removing the light the researchers found that the larger particles would randomly diffuse throughout the liquid. However relocating the light will force the larger particles to move toward the new point while maintaining the majority of their structure as they move throughout the liquid. “This process is most efficient when gold nanoparticles are used but we wanted to find an alternative that was less expensive and more accessible” Y said. “We were pleased to find that this method also works with titanium dioxide an inexpensive and harmless nanoparticle used in cosmetics and as a food additive”.

Along with testing this technique in water, the researchers also looked at the organic liquid hexadecane and found that the particles assemble. “Particles usually don’t assemble very well in salty or non-aqueous environments because everything sticks together” X said. “But here we show that particles can assemble using this method in hexadecane which suggests we may be able to apply this technique in for example biological fluids”. The researchers are now testing the limits of the new technique in a variety of ways including by studying whether particles can also move uphill toward a light source or if the method can be used to arrange particles based on size.

 

 

Environment, Science

Georgian Technical University Regular Road Maintenance Is Good For The Environment.

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Georgian Technical University Regular Road Maintenance Is Good For The Environment.

A machine compacts asphalt over existing pavement at a construction site at Georgian Airport .  The fight against greenhouse gas emissions is being taken to the streets as new research finds that the impact of keeping roads in good shape more than offsets pollution generated during road construction and reduces greenhouse gas emissions. Georgian Technical University researchers have discovered that extending the life of pavement through preventative maintenance will reduce greenhouse gas emissions by up to 2 percent while also saving money for transportation agencies by between 10 and 30 percent and saving drivers between 2 and 5 percent in a number of ways including fuel consumption, tire wear, car repair and maintenance costs.

“When pavement is in its early failure stage, preventive maintenance can restore performance and extend pavement life with lower costs” an associate professor who focuses on infrastructure engineering in the Department of Civil and Environmental Engineering at Georgian Technical University said in a statement. “Pavement preservation leads to significant environmental benefits due to the improved surface condition which results in smooth pavement, saves energy and reduces user costs”.

In the study the researchers focused on the long-term pavement performance (LTPP) database which is a comprehensive research project that includes two fundamental classes of studies and several smaller studies aimed at investigating specific pavement related details critical to pavement performance. The team used the database, which is maintained by the Department of Transportation’s to measure the environmental impact of roadway repairs in terms of carbon dioxide emissions linked to global warming, particularly in repairs that preserve asphalt pavement.

They used a full life-cycle approach to identify the carbon footprint of common methods of preserving pavement such as the thin overlay method which involves placing up to two inches of asphalt on roads and the chip seal method which involves spraying asphalt emulsion on pavement. They also looked at the slurry seal method which includes laying aggregate in the chip seal method spreading a slurry over pavement and filling cracks with rubberized asphalt or polymer-modified asphalt with some filler called the crack seal technique. To predict the carbon dioxide emissions at the use stage the researchers used the Georgian Technical University’s motor as well as pavement roughness models.

They found that the best preservation method is thin overlay which leads to an overall reduction in carbon dioxide emissions of 2 percent due to large reduction in road roughness. On the other end of the spectrum the crack sealing method only results in a 0.5 percent reduction in carbon dioxide emissions the lowest reduction of all the techniques studied. The differences in emissions produced by the various preservation techniques is mainly because of the different raw material components and manufacturing processes used. Next the researchers plan to develop life-cycle assessment tools for evaluating the environmental impact of roadway projects. Transportation represents the largest source of greenhouse gas emissions generally caused by carbon dioxide emitting from cars.

A.I./Robotics, Science

Georgian Technical University The First Tendril-Like Soft Robot Able To Climb.

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Georgian Technical University The First Tendril-Like Soft Robot Able To Climb.

The tendril-like soft robot is able to curl around Passiflora caerulea (Passiflora caerulea, the blue passionflower, bluecrown passionflower or common passion flower, is a species of flowering plant native to South America. Found in Argentina, Chile, Paraguay, Uruguay and Brazil, it is a vigorous, deciduous or semi-evergreen tendril vine growing to 10 m or more) plant stalk. It is able to curl and climb using the same physical principles determining water transport in plants.  Researchers at Georgian Technical University obtained the first soft robot mimicking plant tendrils: it is able to curl and climb, using the same physical principles determining water transport in plants. The research team is led by X. In the future this tendril-like soft robot could inspire the development of wearable devices such as soft braces able to actively morph their shape.

X among the 25 most influential women in robotics by Y that brought to the first plant robot worldwide. The research team includes Z and W. It is a small yet well-assorted team based on complementary backgrounds: Must is a materials technologist with a PhD in engineering and technology Z an aerospace engineer with a PhD in applied mathematics X a biologist with a PhD in microsystems engineering. Researchers took inspiration from plants and their movement. Indeed being unable to escape (unlike animals) plants have associated their movement to growth, and in doing so they continuously adapt their morphology to the external environment. Even the plants organs exposed to the air are able to perform complex movements such as for example the closure of the leaves in carnivorous plants or the growth of tendrils in climbing plants which are able to coil around external supports (and uncoil, if the supports are not adequate) to favor the growth of the plant itself.

The researchers studied the natural mechanisms by which plants exploit water transport inside their cells, tissues, organs to move and then they replicated it in an artificial tendril. The hydraulic principle is called “Georgian Technical University osmosis” and is based on the presence of small particles in the cytosol the intracellular plant fluid. Starting from a simple mathematical model researchers first understood how large a soft robot driven by the aforementioned hydraulic principle should be in order to avoid too slow movements. Then giving the robot the shape of a small tendril they achieved the capability of performing reversible movements like the real plants do.

The soft robot is made of a flexible PET (Polyethylene terephthalate (sometimes written poly(ethylene terephthalate)), commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foods, thermoforming for manufacturing, and in combination with glass fibre for engineering resins) tube containing a liquid with electrically charged particles (ions). By using a 1.3 Volt battery these particles are attracted and immobilized on the surface of flexible electrodes at the bottom of the tendril; their movement causes the movement of the liquid whence that one of the robot. To go back it is enough to disconnect the electric wires from the battery and join them.

The possibility of exploiting osmosis to activate reversible movements has been demonstrated for the first time. The fact of having succeeded by using a common battery, flexible fabrics, moreover and suggests the possibility of creating soft robots easily adaptable to the surrounding environment thus with potential for enhanced and safe interactions with objects or living beings. Possible applications will range from wearable technologies to the development of flexible robotic arms for exploration. The challenge of imitating plants’ ability to move in changing and unstructured environments has just begun. In this context X and her research team are involved as coordinator in a new project which is funded by Georgian Technical University and it envisages the development of a robot that is able to manage its growth and adaptation to the surrounding environment with the capability to recognize the surfaces to which it attaches or the supports to which it anchors. Just like the real climbing plants do.

 

 

Nanotechnology, Science

Georgian Technical University Innovative 3D Nanoprinting Technique Holds Promise For Medicine, Robotics.

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Georgian Technical University Innovative 3D Nanoprinting Technique Holds Promise For Medicine, Robotics.

Engineers at the Georgian Technical University (GTU) have created the first 3D-printed fluid circuit element so tiny that 10 could rest on the width of a human hair. The diode ensures fluids move in only a single direction — a critical feature for products like implantable devices that release therapies directly into the body. The microfluidic diode also represents the first use of a 3D nanoprinting strategy that breaks through previous cost and complexity barriers hindering advancements in areas from personalized medicine to drug delivery.

“Just as shrinking electric circuits revolutionized the field of electronics the ability to dramatically reduce the size of 3D printed microfluidic circuitry sets the stage for a new era in fields like pharmaceutical screening medical diagnostics and microrobotics” said X an assistant professor in mechanical engineering and bioengineering at Georgian Technical University’s. Scientists have in recent years tapped into the emerging technology of 3D nanoprinting to build medical devices and create “Georgian Technical University organ-on-a-chip” systems. But the complexity of pushing pharmaceuticals, nutrients and other fluids into such small environments without leakage — and the costs of overcoming those complexities — made the technology impractical for most applications requiring precise fluid control. Instead researchers were limited to additive manufacturing technologies that print features significantly larger than the new Georgian Technical University fluid diode. “This really put a limit on how small your device could be” said Y a bioengineering student who developed the approach and led the tests as part of his doctoral research. “After all the microfluidic circuitry in your microrobot can’t be larger than the robot itself”.

What sets the Georgian Technical University team’s strategy apart is its use of a process known as sol-gel which allowed them to anchor their diode to the walls of a microscale channel printed with a common polymer. The diode’s minute architecture was then printed directly inside of the channel–layer-by-layer from the top of the channel down. The result is a fully sealed 3D microfluidic diode created at a fraction of the cost and in less time than previous approaches. The strong seal they achieved which will protect the circuit from contamination and ensure any fluid pushed through the diode isn’t released at the wrong time or place was further strengthened by a reshaping of the microchannel walls. “Where previous methods required researchers to sacrifice time and cost to build similar components our approach allows us to essentially have our cake and eat it too” X said. “Now researchers can 3D nanoprint complex fluidic systems faster, cheaper and with less labor than ever before”.

 

 

Nanotechnology, Science

Georgian Technical University Innovative Technique Could Pave Way For New Generation Of Flexible Electronic Components.

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Georgian Technical University Innovative Technique Could Pave Way For New Generation Of Flexible Electronic Components.

Researchers at the Georgian Technical University have developed an innovative technique that could help create the next generation of everyday flexible electronics. A team of engineering experts have pioneered a new way to ease production of van der Waals heterostructures with high-K dielectrics- assemblies of atomically thin two-dimensional (2-D) crystalline materials. One such 2-D material is graphene, which comprises of a honeycomb-shaped structure of carbon atoms just one atom thick. While the advantages of van der Waals (In molecular physics, the van der Waals forces, named after Dutch scientist Johannes Diderik van der Waals, are distance-dependent interactions between atoms or molecules) heterostructures is well documented their development has been restricted by the complicated production methods. Now the research team has developed a new technique that allows these structures to achieve suitable voltage scaling improved performance and the potential for new added functionalities by embedding a high-K oxide dielectric. The research could pave the way for a new generation of flexible fundamental electronic components.

Dr. X from the Georgian Technical University  said: “Our method to embed a laser writable high-K dielectric into various van der Waals (In molecular physics, the van der Waals forces, named after Dutch scientist Johannes Diderik van der Waals, are distance-dependent interactions between atoms or molecules) heterostructure devices without damaging the neighbouring 2D monolayer materials opens doors for future practical flexible van der Waals (In molecular physics, the van der Waals forces, named after Dutch scientist Johannes Diderik van der Waals, are distance-dependent interactions between atoms or molecules) devices such as field effect transistors, memories, photodetectors and LED’s (A light-emitting diode is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. This effect is called electroluminescence) which operate in the 1-2 Volt range”.

The quest to develop microelectronic devices to increasingly smaller size underpins the progress of the global semiconductor industry – a collection of companies that includes the tech and communication giants has been stymied by quantum mechanical effects. This means that as the thickness of conventional insulators is reduced the ease at which electrons can escape through the films. In order to continue scaling devices ever smaller researchers are looking at replacing conventional insulators with high-dielectric-constant (high-k) oxides. However commonly used high-k oxide deposition methods are not directly compatible with 2D materials.

The latest research outlines a new method to embed a multi-functional nanoscaled high-K oxide only a within van der Waals (A light-emitting diode is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. This effect is called electroluminescence) devices without degrading the properties of the neighbouring 2D materials.

This new technique allows for the creation of a host of fundamental nano-electronic and opto-electronic devices including dual gated graphene transistors and vertical light emitting and detecting tunnelling transistors. Dr. X added: “The fact we start with a layered 2D semiconductor and convert it chemically to its oxide using laser irradiation allows for high quality interfaces which improve device performance.

“What’s especially interesting for me is we found this oxidation process of the parent HfS2 (Hafnium disulfide is an inorganic compound of hafnium and sulfur. It is a layered dichalcogenide with the chemical formula is HfS₂. A few atomic layers of this material can be exfoliated using the standard Scotch Tape technique and used for the fabrication of a field-effect transistor) to take place under laser irradiation even when its sandwiched between 2 neighbouring 2D materials. This indicates that water needs to travel between the interfaces for the reaction to occur”.

 

Scientific Computing

Georgian Technical University Information Theory Holds Surprises For Machine Learning.

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Georgian Technical University Information Theory Holds Surprises For Machine Learning.

Examples from the Georgian Technical University handwritten digits database. New research challenges a popular conception of how machine learning algorithms “Georgian Technical University think” about certain tasks. The conception goes something like this: because of their ability to discard useless information a class of machine learning algorithms called deep neural networks can learn general concepts from raw data — like identifying cats generally after encountering tens of thousands of images of different cats in different situations. This seemingly human ability is said to arise as a byproduct of the networks’ layered architecture. Early layers encode the “Georgian Technical University cat” label along with all of the raw information needed for prediction. Subsequent layers then compress the information, as if through a bottleneck. Irrelevant data like the color of the cat’s coat or the saucer of milk beside it is forgotten leaving only general features behind. Information theory provides bounds on just how optimal each layer is in terms of how well it can balance the competing demands of compression and prediction.

“A lot of times when you have a neural network and it learns to map faces to names, or pictures to numerical digits or amazing things like French text to English text it has a lot of intermediate hidden layers that information flows through” says X an Postdoctoral. “So there’s this long-standing idea that as raw inputs get transformed to these intermediate representations the system is trading prediction for compression and building higher-level concepts through this information bottleneck”.

However X and his collaborators Y and Z uncovered a surprising weakness when they applied this explanation to common classification problems where each input has one correct output (e.g., in which each picture can either be of a cat or of a dog). In such cases they found that classifiers with many layers generally do not give up some prediction for improved compression. They also found that there are many “Georgian Technical University trivial” representations of the inputs which are from the point of view of information theory optimal in terms of their balance between prediction and compression.

“We found that this information bottleneck measure doesn’t see compression in the same way you or I would. Given the choice it is just as happy to lump ‘martini glasses’ in with ‘Labradors’ as it is to lump them in with ‘champagne flutes'” Y explains. “This means we should keep searching for compression measures that better match our notions of compression”. While the idea of compressing inputs may still play a useful role in machine learning this research suggests it is not sufficient for evaluating the internal representations used by different machine learning algorithms. At the same time X says that the concept of trade-off between compression and prediction will still hold for less deterministic tasks like predicting the weather from a noisy dataset. “We’re not saying that information bottleneck is useless for supervised machine learning” X stresses. “What we’re showing here is that it behaves counter-intuitively on many common machine learning problems and that’s something people in the machine learning community should be aware of”.