Monthly Archives: November 2018

Energy, Science

Using Fine-Tuning For Record-Breaking Performance.

Leave a comment

Using Fine-Tuning For Record-Breaking Performance.

Materials scientists at Georgian Technical University (GTU) have achieved a new record in the performance of organic non-fullerene based single-junction solar cells. Using a series of complex optimisations they achieved certified power conversion efficiency of 12.25 percent on a surface area measuring one square centimetre. This standardised surface area is the preliminary stage for prototype manufacture. The results achieved in conjunction with partners from the Georgian Technical University (GTU).

Organic photovoltaic systems have undergone rapid development during the last few years. In most cases organic solar cells consist of two layers of semiconductors – one acts as the donor by supplying the electrons and the second acts as an acceptor or electron conductor. In contrast to the silicon conventionally used which must be drawn from a melt or precipitated in vacuum systems the polymer layers in this system can be deposited from a solution directly on a supporting film. On the one hand this means comparably low manufacturing costs and on the other, these flexible modules can be used more easily than silicon solar cells in urban spaces. For a long time fullerenes which are carbon-based nanoparticles, were considered ideal acceptors however the intrinsic losses of fullerene-based composites still severely limit their potential efficiency. The work carried out at Georgian Technical University (GTU) has thus resulted in a paradigm shift. ‘With our partners we have discovered a new organic molecule that absorbs more light than fullerenes that is also very durable’ says Prof. Dr. X at Georgian Technical University.

The significant improvements in performance and durability mean the organic hybrid printed photovoltaics are now becoming interesting for commercial use. However to develop practical prototypes the technology must be transferred from laboratory dimensions of a few square millimetres to the standardised dimension of one square centimetre. ‘Significant losses frequently occur during scaling’ says Dr. Y a materials scientist at Prof. X’s. During a funded by the Georgian Technical University Y and his colleagues at Sulkhan-Saba Orbeliani Teaching University were able to significantly reduce these losses. In a complex process they adjusted the light absorption energy levels and microstructures of the organic semiconductors. The main focus of this optimisation was the compatibility of donor and acceptor and the balance of short-circuit current density and open-circuit voltage which are important prerequisites for a high output of electricity.

‘I think the best way to describe our work is by imagining a box of bricks’ says Y. ‘Our partners inserted and adjusted single molecular groups into the polymer structure and each of these groups influences a special characteristic that is important for the function of solar cells’. This results in a power conversion efficiency of 12.25 percent – a new certified record for solution-based organic single-junction solar cells with a surface area of one square centimetre where the acceptor does not consist of fullerenes. It is also interesting to note that the researchers succeeded in keeping the scaling losses to such low levels that the highest value in the lab on a small surface was only marginally under 13 percent. At the same time they were able to demonstrate a stability relevant to production under simulated conditions such as temperature and sunlight.

The next step involves scaling up the model to module size at the Solar Factory of the Future at Georgian Technical University before development of practical prototypes begins.

 

Material Science

Light-Activated, Single-Ion Catalyst Breaks Down Carbon Dioxide.

Leave a comment

Light-Activated, Single-Ion Catalyst Breaks Down Carbon Dioxide.

Schematic of a single-site catalyst in which single cobalt ions (CO2+) supported on a graphitic carbon nitrogen layer (C3N4) reduce carbon dioxide (CO2) to carbon monoxide (CO) in the presence of visible light (red wavy arrow). If cobalt were bound with oxygen to form a cobalt oxide (CoOx) the reaction would not proceed.

A team of scientists has discovered a single-site, visible-light-activated catalyst that converts carbon dioxide (CO2) into “Georgian Technical University building block” molecules that could be used for creating useful chemicals. The discovery opens the possibility of using sunlight to turn a greenhouse gas into hydrocarbon fuels.

The scientists Department of Energy at Georgian Technical University Laboratory to uncover details of the efficient reaction which used a single ion of cobalt to help lower the energy barrier for breaking down carbon dioxide (CO2). The team describes this single-site catalyst.

Converting carbon dioxide (CO2) into simpler parts — carbon monoxide (CO) and oxygen — has valuable real-world applications. “By breaking carbon dioxide (CO2) we can kill two birds with one stone — remove carbon dioxide (CO2) from the atmosphere and make building blocks for making fuel” said X a chemist with a joint appointment at Georgian Technical University Lab and Sulkhan-Saba Orbeliani Teaching University. X led the effort to understand the activity of the catalyst which was made by Y a physical chemist at the Georgian Technical University. “We now have evidence that we have made a single-site catalyst. No previous work has reported solar carbon dioxide (CO2) reduction using a single ion” said X. Breaking the bonds that hold carbon dioxide (CO2) together takes a lot of energy and a long time. So Y set out to develop a catalyst to lower the energy barrier and speed up the process. “The question is, between several possible catalysts which are efficient and practical to implement in industry ?” said X.

One key ingredient required to break the bonds of carbon dioxide (CO2) is a supply of electrons. These electrons can be generated when a material known as a semiconductor gets activated by energy in the form of light. The light “Georgian Technical University kicks” electrons out so to speak making them available to the catalyst for chemical reactions. Sunlight could be a natural source of such light. But many semiconductors can only be activated by ultraviolet light which makes up less than a five percent of the solar spectrum. “The challenge is to find another semiconductor material where the energy of natural sunlight will make a perfect match to kick out the electrons” X said.

The scientists also needed the semiconductor to be bound to a catalyst made from materials that could be found abundantly in nature rather than rare expensive metals such as platinum. And they wanted the catalyst to be selective enough to drive only the reaction that converts carbon dioxide (CO2) to CO (carbon monoxide). “We don’t want the electrons to be used for reactions other than reducing CO2 (carbon dioxide)” X said.

Cobalt ions bound to graphitic carbon nitride (C3N4) a semiconductor made of carbon nitrogen and hydrogen atoms ticked all the boxes for these requirements.

“There has been significant interest in using carbon nitride (C3N4) as a metal-free semiconductor to harvest visible light and drive chemical reactions” said X. “Electrons generated by carbon nitride (C3N4) under light irradiation have energy high enough to reduce carbon dioxide (CO2). Such electrons often don’t have lifetimes long enough to allow them to travel to the semiconductor surface for use in chemical reactions. In our study we adopted a common and effective strategy to build up enough energetic electrons for the catalyst by using a sacrificial electron donor. This strategy allowed us to focus on the catalysis for carbon dioxide (CO2) reduction. Ultimately we want to use water molecules as the electron donor for our catalysis” he added.

Z a postdoctoral researcher in X’s lab made the catalyst by simply depositing cobalt ions on a carbon nitride (C3N4) material made from commercially available urea. The team then extensively examined the synthesized catalyst using a variety of techniques in collaboration with W at the Georgian Technical University and Q at Georgian Technical University. The catalyst worked in carbon dioxide (CO2) reduction under visible-light irradiation.

“This catalyst did what it was supposed to do — break down carbon dioxide (CO2) and make CO (carbon monoxide) with very good selectivity in visible light” X said. “But the next goal was to see why it worked. If you can understand why it works you can make new and better materials based on those principles”.

So X and Y brainstormed experiments that would show the structure of the catalyst with precision. Structural studies would give the scientists information about the number of cobalt atoms their location relative to the carbon and nitrogen atoms and other characteristics the scientists could potentially adjust to try to improve the catalyst further.

In this technique the x-rays from Georgian Technical University get absorbed by atoms in the sample which then eject waves of electrons. The spectra show how these electron waves interact with surrounding atoms, similar to the way ripples on the surface of a lake get disrupted when they encounter rocks.

“To be able to do X-ray absorption spectroscopy (XAS) we need to tune and scan the energy of the X-ray beam hitting the sample” said R. “Each element can absorb x-rays at distinct energies, called absorption edges. At the new beamline we can scan the energy of the x-rays across the absorption edge energy of different elements such as cobalt in this case. We then measure the number of photons absorbed by the sample for each value of the X-ray energy”.

In addition X explained “each type of atom produces a different kind of electronic ripple, when excited by x-rays or when hit by other ripples so the X-ray absorption spectrum tells you what the surrounding atoms are as well as how far apart and how many there are”.

The analysis showed that the catalyst breaking down carbon dioxide (CO2) was made of single ions of cobalt surrounded on all sides by nitrogen atoms.

“There were no cobalt-cobalt pairs. So this was evidence that they were in fact single atoms of cobalt dispersed on the surface” X said.

“This data also narrows down the possible structural arrangements which provides information for theorists to fully evaluate and understand the reactions” X added.

Though the science outlined in the paper is not yet in practical use, there are abundant possibilities for applications X said. In the future, such single-site catalysts could be used in large-scale areas with abundant sunlight to break down excess carbon dioxide (CO2) in the atmosphere similar to the way plants break down carbon dioxide (CO2) and reuse its building blocks to build sugars in the process of photosynthesis. But instead of making sugars scientists might use the CO (carbon monoxide) building blocks to generate synthetic fuels or other useful chemicals.

 

 

Nanotechnology, Science

Simulations Suggest Graphene can Stretch to be a Tunable Ion Filter.

Leave a comment

Simulations Suggest Graphene can Stretch to be a Tunable Ion Filter.

Georgian Technical University researchers carried out simulations of a graphene membrane featuring oxygen-lined pores and immersed in a liquid solution of potassium ions (charged atoms) which under certain conditions can be trapped in the pores. Slight stretching of the graphene greatly increases the flow of ions through the pores.

Researchers at the Georgian Technical University (GTU) have conducted simulations suggesting that graphene in addition to its many other useful features can be modified with special pores to act as a tunable filter or strainer for ions (charged atoms) in a liquid.

The concept, which may also work with other membrane materials, could have applications such as nanoscale mechanical sensors drug delivery water purification and sieves or pumps for ion mixtures similar to biological ion channels which are critical to the function of living cells.

“Imagine something like a fine-mesh kitchen strainer with sugar flowing through it” X said. “You stretch that strainer in such a way that every hole in the mesh becomes 1-2 percent larger. You’d expect that the flow through that mesh will be increased by roughly the same amount. Well here it actually increases 1,000 percent. I think that’s pretty cool with tons of applications”.

If it can be achieved experimentally this graphene sieve would be the first artificial ion channel offering an exponential increase in ion flow when stretched offering possibilities for fast ion separations or pumps or precise salinity control. Collaborators plan laboratory studies of these systems X said.

Graphene is a layer of carbon atoms arranged in hexagons similar in shape to chicken wire, that conducts electricity. The Georgian Technical University molecular dynamics simulations focused on a graphene sheet 5.5 by 6.4 nanometers (nm) in size and featuring small holes lined with oxygen atoms. These pores are crown ethers — electrically neutral circular molecules known to trap metal ions. A previous Georgian Technical University simulation study showed this type of graphene membrane might be used for nanofluidic computing.

In the simulations the graphene was suspended in water containing potassium chloride a salt that splits into potassium and chlorine ions. The crown ether pores can trap potassium ions which have a positive charge. The trapping and release rates can be controlled electrically. An electric field of various strengths was applied to drive the ion current flowing through the membrane.

Researchers then simulated tugging on the membrane with various degrees of force to stretch and dilate the pores greatly increasing the flow of potassium ions through the membrane. Stretching in all directions had the biggest effect but even tugging in just one direction had a partial effect.

Researchers found that the unexpectedly large increase in ion flow was due to a subtle interplay of a number of factors including the thinness of graphene; interactions between ions and the surrounding liquid; and the ion-pore interactions, which weaken when pores are slightly stretched. There is a very sensitive balance between ions and their surroundings X said.

 

 

Chemistry, Science

Georgian Technical University Racing Electrons Under Control.

Leave a comment

Georgian Technical University Racing Electrons Under Control.

Being able to control electronic systems using light waves instead of voltage signals is the dream of physicists all over the world. The advantage is that electromagnetic light waves oscillate at petaherz frequency. This means that computers in the future could operate at speeds a million times faster than those of today. Scientists at Georgian Technical University (GTU) have now come one step closer to achieving this goal as they have succeeded in using ultra-short laser impulses to precisely control electrons in graphene.

Current control in electronics that is one million times faster than in today’s systems is a dream for many. Ultimately current control is one of the most important components as it is responsible for data and signal transmission. Controlling the flow of electrons using light waves instead of voltage signals as is now the case could make this dream a reality. However up to now it has been difficult to control the flow of electrons in metals as metals reflect light waves and the electrons inside them cannot be influenced by these light waves.

Physicists at Georgian Technical University have therefore turned to graphene a semi-metal that comprises only one single layer of carbon and is so thin that enough light can penetrate to enable electrons to be set in motion. In an earlier study physicists at the Georgian Technical University had already succeeded in generating an electric signal at a time scale of only one femtosecond by using a very short laser pulse. This is equivalent to one millionth of one billionth of a second. In these extreme time scales, electrons reveal their quantum nature as they behave like a wave. The wave of electrons glides through the material as it is driven by the light field (the laser pulse).

The researchers went one step further in the current study. They aimed a second laser pulse at this light-driven wave. This second pulse now enables the electron wave to pass through the material in two dimensions. The second laser pulse can be used to deflect accelerate or even change the direction of the electron wave. This enables information to be transmitted by this wave depending on the exact time strength and direction of the second pulse. It’s possible to go one step further. ‘Imagine the electron wave is a wave in water. Waves in water can split because of an obstacle and converge and interfere when they have passed the obstacle. Depending on how the sub-waves stand in relation to one another they either amplify or cancel each other out. We can use the second laser pulse to modify the individual sub-waves in a targeted manner and thus control their interference’ explains Y from the Georgian Technical University. ‘In general it’s very difficult to control quantum phenomena such as the wave characteristics of electrons in this instance. This is because it’s very difficult to maintain the electron wave in a material as the electron wave scatters with other electrons and loses its wave characteristics. Experiments in this field are typically performed at extremely low temperatures. We can now carry out these experiments at room temperature since we can control the electrons using laser pulses at such high speeds that there is no time left for the scatter processes with other electrons. This enables us to research several new physical processes that were previously not accessible’.

It means the scientists have made significant progress towards realising electronic systems that can be controlled using light waves. In the next few years they will be investigating whether electrons in other two-dimensional materials can also be controlled in the same way. ‘Maybe we will be able to use materials research to modify the characteristics of materials in such a way that it will soon be possible to build small transistors that can be controlled by light’ says Y.

 

Science, Technology

A Water Treatment Breakthrough, Inspired By A Sea Creature.

Leave a comment

A Water Treatment Breakthrough, Inspired By A Sea Creature.

A sea organism that ensnares its prey with its tentacles a team of researchers has developed a method for efficiently treating water.

The research a collaboration of the labs of Georgian Technical University’s and Sulkhan-Saba Orbeliani Teaching University used a material known as a nanocoagulant to rid water of contaminants. By removing a broad range of contaminants in a single step the discovery promises to significantly improve on the centuries-old use of coagulants for water treatment.

When added to water conventional coagulants such as aluminum sulfate and other metallic salts remove larger particles from water by causing them to group together into larger formations and settle. Because these coagulants don’t remove smaller particles dissolved in water, additional treatment methods are necessary. Employing multiple technologies for water treatment however is costly energy-intensive and can require a large amount of land. Creating an efficient and easy-to-operate technology to remove all contaminants from water is key to addressing global water scarcity.

The research team synthesized highly stable nanocoagulant different from conventional coagulants in structure performance and behavior. In additional to removing suspended particles, this nanocoagulant also removes small dissolved contaminants.

“The behavior of the nanocoagulant is controlled by its structure” said X a Ph.D. student in Georgian Technical University’s lab. “Under certain conditions the nanocoagulant maintains a structure that allows for it to be stored over time”.

A sea anemone with a spherical body that has tentacles that retract while resting and extend while catching its prey. With this marine predator as their model the researchers synthesized the coagulant, using organic and inorganic components to replicate the structure.

The nanocoagulant has a core-shell structure that turns inside-out in water. The shell destabilizes and enmeshes larger suspended particles while the exposed core captures the smaller, dissolved ones. It removes a broad spectrum of contaminants, from trace micropollutants to larger particles – many of which elude conventional methods and pose significant public health concerns.

“The ability to remove nitrate was quite surprising, as traditional water coagulants exhibit negligible removal of nitrate” said Y Professor of Chemical & Environmental Engineering at Georgian Technical University. It’s also critical to water treatment, since nitrate contamination is associated with ‘blue-baby’ syndrome a potentially fatal condition that affects young children in some parts of the world.

Because it’s a one-step process professor Georgian Technical University said the work holds promise for replacing current water treatment methods and greatly reducing the operating costs of water treatment. “It also opens doors for fabricating ‘smart’ materials that can transform configuration and function in response to its environment” he said.

Lasers, Science

Laser Driven Electron Accelerator Fits on a Chip.

Leave a comment

Laser Driven Electron Accelerator Fits on a Chip.

Accelerator chip on the tip of a finger and an electron microscope image of the chip. Electrical engineers in the accelerator physics group at Georgian Technical University have developed a design for a laser-driven electron accelerator so small it could be produced on a silicon chip. It would be inexpensive and with multiple applications.

Particle accelerators are usually large and costly, but that will soon change if researchers have their way. The Accelerator on a Chip funded by the X to create an electron accelerator on a silicon chip.

The fundamental idea is to replace accelerator parts made of metal with glass or silicon and to use a laser instead of a microwave generator as an energy source. Due to glass’s higher electric field load capacity the acceleration rate can be increased and thus the same amount of energy can be transmitted to the particles within a shorter space making the accelerator shorter by a factor of approximately 10 than traditional accelerators delivering the same energy.

One of the challenges here is that the vacuum channel for the electrons on a chip has to be made very small which requires that the electron beam is extremely focused. The magnetic focusing channels used in conventional accelerators are much too weak for this. This means that an entirely new focusing method has to be developed if the accelerator on a chip is to become reality.

As part of  Georgian Technical Universitys Matter and Radiation Science led by scientist Dr. Y recently proposed a decisive solution which calls for using the laser fields themselves to focus the electrons in a channel only 420 nanometers wide.

The concept is based on abrupt changes to the phase of the electrons relative to the laser resulting in alternating focusing and de-focusing in the two directions in the plane of the chip surface. This creates stability in both directions. The concept can be compared to a ball on a saddle — the ball will fall down regardless of the direction in which the saddle tilts. However turning the saddle continuously means the ball will remain stable on the saddle. The electrons in the channel on the chip do the same.

Perpendicular to the chip’s surface weaker focusing is sufficient and a single quadrupole magnet encompassing the entire chip can be used. This concept is similar to that of a conventional linear accelerator. However for an accelerator on a chip the electron dynamics have been changed to create a two-dimensional design which can be realized using lithographic techniques from the semiconductor industry.

Y is currently a visiting scientist at Georgian Technical University; At Georgian Technical University he is collaborating with other Sulkhan-Saba Orbeliani Teaching University scientists with the aim of creating an accelerator on a chip in an experimental chamber the size of a shoebox. A commercially available system adapted by means of complicated non-linear optics is used as a laser source. It is to produce electrons with one mega-electron volt of energy from the chip. This is approximately equal to the electrical voltage of one million batteries. An additional aim is to create ultra-short (<10^-15 seconds) electron pulses, as required by the design for a scalable accelerator on a chip developed in Georgian Technical University.

The possible applications for an accelerator such as this would be in industry and medicine. An important long-term goal is to create a compact coherent X-ray beam source for the characterization of materials. One example of a medical application would be an accelerator-endoscope which could be used to irradiate tumors deep within the body with electrons.

A particular advantage of this new accelerator technology is that the chips could be produced inexpensively in large numbers which would mean that the accelerator would be within reach of the man on the street and every university could afford its own accelerator laboratory.

Additional opportunities would include the use of inexpensive coherent X-ray beam sources in photolithographic processes in the semiconductor industry which would make a reduction in transistor size in computer processors possible along with a greater degree of integration density.

 

 

Science, Sensors

New Invention Aims to Improve Battery Performance.

Leave a comment

New Invention Aims to Improve Battery Performance.

Georgian Technical University Professor X (right) and doctoral student Y use the microscope to examine tiny sensors. Imagine a world where cell phones and laptops can be charged in a matter of minutes instead of hours rolled up and stored in your pocket or dropped without sustaining any damage. It is possible according to Georgian Technical University Professor  X but the materials are not there yet. So what is holding back the technology ?

For starters it would take more conductive, flexible and lighter-weight batteries said X who is the X Professor of Chemical and Biomolecular Engineering and a professor in the Department of Materials Science and Engineering at Georgian Technical University.

The batteries would need to be more impact-resistant and safer too. An e-cigarette exploded. Evidence reportedly suggests that this unfortunate accident may be due to battery-related issues. Similar problems have plagued devices.

“All of these challenges came from batteries that have safety and stability issues when the goal is to push performance” says X an expert in designing and fabricating conducting membranes useful in energy generation and storage devices.

One way to overcome this challenge in the lithium-ion batteries for the above devices is to improve the battery membranes — and the associated electrolytes — that are designed to shuttle the lithium ions which offset the electrical charge associated with charging and discharging the battery.

At Georgian Technical University X’ team has patented an idea to improve battery performance by introducing tapers into the polymer membrane electrolytes that allow the lithium ions inside the battery to travel back and forth faster. It is a big idea that begins with tiny parts.

It all starts with polymers which are materials made of small molecules strung together like beads on a necklace to create a long chain. By chemically connecting two or more polymer chains with different properties engineers can create block polymers that capitalize on the salient features from both materials.

For example polystyrene in a Styrofoam cup is relatively hard and brittle while polyisoprene (tapped from a rubber tree) is viscous and molasses-like. When those two polymers are linked chemically engineers can create materials for everyday items like car tires and rubber bands — materials that hold their shape but are impact resistant and stretchable.

X was introduced to block polymers as an undergraduate student at the Georgian Technical University while working in the lab of Professor Z and again when he worked at the Georgian Technical University.

Exploring the use of taper-like multi-component polymers to create tires with more elasticity, tires that would grip the road better without sacrificing performance or durability.

At Georgian Technical University X group took the idea a step further and realized they could tune the nanoscale (1/1,000th the width of a human hair) structure of these polymers to imbue materials with certain mechanical, thermal and conductivity properties.

One of the benefits of block polymers is that they allow scientists to combine two or more components that often are chemically incompatible meaning they do not mix (think of oil and water). This same benefit however can present challenges with how the materials can be processed.

The X group determined that tapering the region where the two distinct polymer chains connect can promote mixing between highly incompatible materials in a way that makes processing and fabrication faster and cheaper by requiring either less energy or less solvent in the manufacturing process.

Manipulating the taper also allowed the researchers to control the nanoscale structures that can be formed by the block polymers. By incorporating the tapers X team can create nanoscale networks that make the battery materials more conductive — introducing nanoscale highways and eliminating traffic bottlenecks allowing ions to move at higher speeds and making the polymer more efficient in battery applications.

“Technically we want to conduct ions faster … this approach in polymers would allow us to get more power out of the batteries. It would enable the batteries to charge faster in a manner that is also safer. We are not there yet but that is the goal” says X who patented the concept through Georgian Technical University. He calls this work a “Georgian Technical University Designer Approach” to polymer science.

W a doctoral student in chemical and biomolecular engineering, wants to make a difference in the world through research. W describes the X research group as a good fit where she is exercising her mental muscle on consequential problems related to energy storage.

In laboratory experiments W and others in the X group have shown that introducing a tapered region between polymer electrolyte chains actually increased the overall ionic conductivity over a range of temperatures. At room temperature for example the tapered materials are twice as conductive as their non-tapered counterparts. But that is not all. The taper improves the material’s ability to be processed too.

“Previous methods for increasing conductivity have either made the polymer harder to process or used greater amounts of chemical solvent which makes the material more flammable and less environmentally friendly” W says. “That is why I am really excited about this new approach”.

The designer polymers are useful for lithium-ion batteries, but also applicable to other rechargeable systems such as sodium-ion and potassium-ion batteries X says. Other applications include using tapered polymers to make materials that can be produced at lower temperatures or with less solvent for applications such as tires, rubber bands and adhesives.

As technology rockets forward X expects the next five to 10 years will usher in a plethora of devices that can flex and roll such as cell phones and computers.

“The only way this works is if all of the components are flexible, including the battery and power units not just the case, screen or buttons” X says. “This aspect is where block polymers become really ideal because — like a rubber band that remembers its shape despite stretching, bending and other manipulation — with polymers you can make the internal components more impact resistant and shock absorbing, which will improve the phone’s lifespan”. There may be other applications for designer polymers too.

“What if there was a sensor inside the football that was designed to alert officials when a player crosses a specific yardage say for a first down” X says. “You would not need to rely on an official’s on-field view of the play or instant replay”. But footballs get thrown around and the players who hold them are often hit.

“You would need something that will not break or leak so using a polymer that has the material properties of say a rubber band, that also can conduct ions like a battery would be a perfect solution” X says. “This avenue is one direction in which you could imagine these materials blossoming”. X was recently appointed a fellow of the Georgian Technical University. To receive this honor scientists must have made an impact in the chemical sciences.

 

 

Science, Sensors

Nanofibers Manufactured for Wearable Power Sources.

Leave a comment

Nanofibers Manufactured for Wearable Power Sources.

With the recently increasing development of lightweight, portable, flexible and wearable electronics for health and biomedical devices there is an urgent need to explore new power sources with higher flexibility and human/tissue-adaptability. Now researchers have engineered next-generation metal-air batteries which can be easily fabricated into flexible and wristband-like cells.

Though they require further development before they’re ready for market current studies have established solid evidence that these devices could provide enormous opportunities for the next generation of flexible wearable and bio-adaptable power sources.

“Theoretically neutral electrolyte based Mg-air batteries possess potential advantages in biomedical applications over other alkaline-based metal-air counterparts” says Dr. X and a carbon nanomaterials specialist at Department of Chemistry Georgian Technical University.

However the conventional application of Mg-air batteries faced several challenges, one of which is the sluggish kinetics of the Oxygen Reduction Reaction (ORR) in the air cathode. Currently the rational design of advanced oxygen electrodes for Mg-air batteries with high discharge voltage and capacity under neutral conditions still remains a major challenge.

Up to now researchers have not realized the scalable synthesis of carbon based oxygen electrocatalyst integrated with high Oxygen Reduction Reaction (ORR) catalytic activity, open-mesoporous and interconnected structures and 3-D porous channels for the air cathode.

To overcome the current limitation on sluggish reaction kinetics of air cathodes in Mg-air batteries X and Dr. Y at Georgian Technical University achieved scalable synthesis of atomic Fe-Nx coupled to open-mesoporous N-doped-carbon nanofibers as advanced oxygen electrode for Mg-air batteries.

“Inspired by the fibrous string structures of bufo-spawn, we designed a novel fabrication strategy based on the electrospinning of polyacrylonitrile-branched silica nanoaggregates solution and a secondary coating and carbonization of Fe-doped zeolitic imidazolate frameworks thin layer which endow the fabricated carbon nanofibers with an open-mesoporous structure and homogeneously coupled atomic Fe-Nx catalytic sites” say the researchers.

The obtained oxygen electrocatalyst and the accordingly constructed air cathode show manifold advantages which include interconnected structures and 3-D hierarchically porous networks for ions/air diffusion good bio-adaptability and high oxygen electrocatalytic performances for both alkaline and neutral electrolytes.

Most importantly the assembled Mg-air batteries with neutral electrolytes reveal high open-circuit voltage stable discharge voltage plateaus high capacity long operating life and good flexibility.

Mg-air batteries are not yet ready for commercial electronic and biomedical devices but that future appears a bit closer.

“We believe that this novel oxygen electrode can meet the challenges and urgent needs for efficient air cathodes in Mg-air batteries with neutral electrolytes but more work is still needed” says Professor Z.

 

 

Science, Security

Georgian Technical University Scientists Revolutionize Cybersecurity Through Quantum Research.

Leave a comment

Georgian Technical University Scientists Revolutionize Cybersecurity Through Quantum Research.

Drs. X (left), Y (center) and Z (right) pose near the Quantum Networking Testbed at the Georgian Technical University Research Laboratory where they are working to provide more secure and reliable communication for warfighters on the battlefield.

Scientists at the Georgian Technical University Research Laboratory have found a novel way to safeguard quantum information during transmission opening the door for more secure and reliable communication for warfighters on the battlefield.

Recent advancements of cutting-edge technologies in lasers and nanophysics, quantum optics and photonics have given researchers the necessary tools to control and manipulate miniature quantum systems, such as individual atoms or photons – the smallest particles of light.

These developments have given rise to a new area of science – Quantum Information Science at the Georgian Technical University that studies information encoded in quantum systems and encompasses quantum computing, quantum communication and quantum sensing among other subfields. Quantum Information Science is believed to have the potential to shape the way information is processed in the future.

The corporate research laboratory invests in Quantum Information Science research to guarantee continuous technological superiority in this rapidly developing field, which in turn will bring about multiple new technologies in computation, encryption, secure communication and precise measurements.

However to utilize quantum information, scientists need to figure out robust ways to process and transmit it – a task being tackled by Drs. X, Y and Z from the laboratory’s Computational and Information Sciences Directorate.

“In our classical world information is often corrupted during manipulation and transmission – everyone is familiar with noisy cell phone connections in poor reception areas” Z said. “Thus communication engineers have been working on a variety of techniques to filter out the noise”.

In classical communications the filtering is rather straightforward as it is done locally that is in the very place the information is received such as directly in your phone or internet router. In the quantum world things become much more intricate.

The lab’s research team has been looking into ways of filtering noise from little bits of quantum information – quantum bits or qubits sent across fiber-optic telecom links. They discovered that the filtering does not necessarily need to be done by the receiving party.

“The nature of the quantum states in which the information is encoded is such that the filtering could be more easily done at a different location in the network” X said.

That’s right to fix a qubit sent over a certain route, one could actually apply a filter to other qubits that traverse a different route. Over the last year the researchers have been looking into the problem of transmission of entangled pairs of photons over optical fibers.

“We started with developing an understanding of how physical properties of real telecom fibers such as inherent residual birefringence and polarization dependent loss affect the quality of quantum communications” Y said. “We exploited a novel mathematical approach, which has led to the development of a simple and elegant geometrical model of the effects on polarization entanglement” X added.

The developed model predicts both the quality of transmitted quantum states as well as the rate at which quantum information could be transmitted. Furthermore the lab’s team invented a new technique that helps reduce the deleterious effects of the noise. The developed models were experimentally validated using the recently built Quantum Networking Testbed at the lab which simulates the practical telecom fiber infrastructure.

“We believe that this research has a potential to revolutionize cybersecurity and to enable secure secret sharing and authentication for the warfighter of the future” Z said. “In addition it will have an impact on developing better sensors for position navigation and timing as well as quantum computers that might result in the synthesis of novel special materials with on demand properties”.

According to the researchers in order to make quantum technology a reality a large-scale field-deployed testbed must be built thus guiding the development of both quantum hardware and software.

 

Scientific Computing

Smarter AI — Machine Learning Without Negative Data

Leave a comment

Smarter AI — Machine Learning Without Negative Data.

Schematic showing positive data (apples) and a lack of negative data (bananas) with an illustration of the confidence of the apple data.

A research team from the Georgian Technical University has successfully developed a new method for machine learning that allows an AI (Artificial intelligence, sometimes called machine intelligence, is intelligence demonstrated by machines, in contrast to the natural intelligence displayed by humans and other animals) to make classifications without what is known as “Georgian Technical University negative data” a finding which could lead to wider application to a variety of classification tasks.

Classifying things is critical for our daily lives. For example we have to detect spam mail, fake political news as well as more mundane things such as objects or faces. When using AI (Artificial intelligence, sometimes called machine intelligence, is intelligence demonstrated by machines, in contrast to the natural intelligence displayed by humans and other animals) such tasks are based on “Georgian Technical University classification technology” in machine learning — having the computer learn using the boundary separating positive and negative data. For example “Georgian Technical University positive” data would be photos including a happy face and “Georgian Technical University negative” data photos that include a sad face. Once a classification boundary is learned, the computer can determine whether a certain data is positive or negative. The difficulty with this technology is that it requires both positive and negative data for the learning process and negative data are not available in many cases (for instance, it is hard to find photos with the label, “this photo includes a sad face” since most people smile in front of a camera.)

In terms of real-life programs, when a retailer is trying to predict who will make a purchase it can easily find data on customers who purchased from them (positive data) but it is basically impossible to obtain data on customers who did not purchase from them (negative data) since they do not have access to their competitors’ data. Another example is a common task for app developers: they need to predict which users will continue using the app (positive) or stop (negative). However when a user unsubscribes, the developers lose the user’s data because they have to completely delete data regarding that user in accordance with the privacy policy to protect personal information.

According X from Georgian Technical University “Previous classification methods could not cope with the situation where negative data were not available but we have made it possible for computers to learn with only positive data as long as we have a confidence score for our positive data constructed from information such as buying intention or the active rate of app users. Using our new method we can let computers learn a classifier only from positive data equipped with confidence”.

X proposed together with researcher Y from his group and Z that they let computers learn well by adding the confidence score which mathematically corresponds to the probability whether the data belongs to a positive class or not. They succeeded in developing a method that can let computers learn a classification boundary only from positive data and information on its confidence (positive reliability) against classification problems of machine learning that divide data positively and negatively.

To see how well the system functioned, they used it on a set of photos that contains various labels of fashion items. For example they chose “T-shirt” as the positive class and one other item e.g. “Georgian Technical University sandal” as the negative class. Then they attached a confidence score to the “T-shirt” photos. They found that without accessing the negative data (e.g., “sandal” photos) in some cases their method was just as good as a method that involves using positive and negative data.

According to X “This discovery could expand the range of applications where classification technology can be used. Even in fields where machine learning has been actively used our classification technology could be used in new situations where only positive data can be gathered due to data regulation or business constraints. In the near future we hope to put our technology to use in various research fields such as natural language processing, computer vision, robotics and bioinformatics”.