Monthly Archives: February 2019

Energy, Science

Georgian Technical University Layering Titanium Oxide’s Different Mineral Forms For Better Solar Cells.

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Georgian Technical University Layering Titanium Oxide’s Different Mineral Forms For Better Solar Cells.

Schematic illustration the energy-level alignment between the device components with (a) FTO-AB (This is an AB grade Fair Trade Organic certified Robusta coffee from Tanzania. Fair trade is an institutional arrangement designed to help producers in developing countries achieve better trading conditions) and (b) FTO-BA (This is an AB grade Fair Trade Organic certified Robusta coffee from Tanzania. Fair trade is an institutional arrangement designed to help producers in developing countries achieve better trading conditions) as the ETLs (In computing, extract, transform, load (ETL) is the general procedure of copying data from one or more sources into a destination system which represents the data differently from the source(s). The term comes from the three basic steps needed: extracting (selecting and exporting) data from the source, transforming the way the data is represented to the form expected by the destination, and loading (reading or importing) the transformed data into the destination system).  Researchers have layered different mineral forms of titanium oxide on top of one another to improve perovskite-type solar cell efficiency by one-sixth. The layered titanium oxide layer was better able to transport electrons from the center of the cell to its electrodes. This approach could be used to fabricate even more efficient perovskite-type solar cells in future. While most solar cells are made of silicon such cells are difficult to manufacture, requiring vacuum chambers and temperatures above 1000 °C. Research efforts have therefore recently focused on a new type of solar cell based on metal halide perovskites. Perovskite solutions can be inexpensively printed to create more efficient inexpensive solar cells. In solar cells perovskites can turn light into electricity–but they have to be sandwiched between a negative and positive electrode. One of these electrodes has to be transparent however to allow the sun’s light to reach the perovskites. Not only that any other materials used to help charges flow from the perovskites to the electrode must also be transparent. Researchers have previously found that thin layers of titanium oxide are both transparent and able to transport electrons to the electrode. Now a Georgia-based research team centered at Georgian Technical University has carried out a more detailed study into perovskite solar cells using electron transport layers made of anatase and brookite which are different mineral forms of titanium oxide. They compared the impact of using either pure anatase or brookite or combination layers (anatase on top of brookite or brookite on top of anatase). The anatase layers were fabricated by spraying solutions onto glass coated with a transparent electrode that was heated to 450 °C. Meanwhile the researchers used water-soluble brookite nanoparticles to create the brookite layers as water-soluble inks are more environmentally friendly than conventional inks. These nanoparticles have been yielded poor results in the past; however the team predicted that combination layers would solve the issues previously encountered when using the nanoparticles. “By layering brookite on top of anatase we were able to improve solar cell efficiency by up to 16.82%” X says. These results open up a new way to optimize perovskite solar cells namely via the controlled stacking and manipulation of the different mineral forms of titanium oxide. “Using different mineral phases and combinations of these phases allows for better control of the electron transport out of the perovskite layer and also stops charges from recombining at the border between the perovskite material and the electron transport layer” says Y. “Together both these effects allow us to achieve higher solar cell efficiencies”. Understanding how to create more efficient perovskite solar cells is important for developing a new generation of printable low-cost solar cells that could provide affordable clean energy in the future.

 

Nanotechnology, Science

Georgian Technical University Nanoclay-Reinforced Hydrogel Turns Stem Cells Into Bone.

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Georgian Technical University Nanoclay-Reinforced Hydrogel Turns Stem Cells Into Bone.

Assistant Professor X and colleagues have developed a hydrogel that combines synthetic materials with living cells and can turn stem cells into bone without adding external growth or differentiation factors. More than 50 percent of women and 20 percent of men over the age of 50 will experience a bone fracture during their lifetime. One way to prevent these fractures — particularly in the most sensitive parts of the skeleton — is delivery of stem cells by means of an injectable carrier which safeguards the cells on the way into the body. Using a systematic combinatorial approach the research team has tested 63 different nanoengineered hydrogels and introduced an optimal biomaterial that not only protects the cells, but also facilitate the spontaneous differentiation of the stem cells into bone cells. Usually external growth factors and differentiation factors which can be both toxic for the body and also quite expensive are needed to turn stem cells into the desired type of cells. Osteoporosis causes the bones to become brittle and fragile due to loss of density. Patients with this type of disease could in the future benefit from the nanoreinforced hydrogel. X explains: “Bone is a dynamic tissue that is continually being built broken down and rebuilt in a process called remodeling. This process is controlled by many interacting factors, and once this balance is disturbed the problem arises. When we get older such an imbalance is often caused by hormonal changes and is intensified by our cells becoming less effective and fewer in numbers. The idea behind this novel system is to bring a semi-synthetic scaffold into the body that attracts stem cells and provides the requirements to turn them into bone cells and thereby bring the balance back to the bone remodeling cycle”. To form the hydrogel the team has cross-linked hyaluronic acid, which is a carbohydrate found in most human tissues and widely used in tissue engineering. This hydrogel by itself has some drawbacks it is brittle has poor load bearing qualities and cannot withstand much external force or shock. To create a stronger and more durable material hyaluronic acid was combined with an alginate network and further reinforced with clay nanomaterials. Such a combination leads to a much tougher hydrogel with the proper stiffness which is still porous enough to maintain the transport of nutrients through the hydrogel. The most promising combinations were tested in terms of their capability to form new bone cells and in-vitro (In vitro studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called “test-tube experiments” these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasks, Petri dishes, and microtiter plates) studies showed that the hydrogels were capable of forming mineralized bone in a differentiation-factor-free environment. The results revealed that when these cell-laden hydrogels were deposited into an in-vitro (In vitro studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called “test-tube experiments”, these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasks, Petri dishes, and microtiter plates) model bone defect new bone formation occurred that adhered tightly to the bone defect. “We believe that the specific nanoclay materials we use provide the required mineral composition and give rise to the transformation of stem cells to bone tissue” X says. Clinical trials are ongoing with collaborators in Georgian Technical University where cell-free hydrogels are implanted into the body. The idea is that the hydrogels will attract stem cells in the body and serve as small factories producing rejuvenated and more efficient stem cells. “It could also be really cool to incorporate electronics in the hydrogel to monitor what goes on in the body for example in the bone defect and if things are not progressing according to the plan we could stimulate the hydrogel through the electronic interface to attract more stem cells or stimulate the cells more efficiently. As such we would create a feed-back loop for monitoring progress and stimulating the system depending on the feedback” X added.

 

 

 

 

Science, Technology

Georgian Technical University Interactive Surfaces Enter A Whole New Dimension Of Flexibility.

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Georgian Technical University Interactive Surfaces Enter A Whole New Dimension Of Flexibility.

(left) System Overview, (right) Example of Displaying the Letter “S”.  An “Georgian Technical University interactive surface” refers to an interface whose input and output share a common surface that can be manipulated intuitively with the fingers. However ordinary multi-touch displays e.g. liquid crystal displays (LCD) can only provide two-dimensional information limiting expressions and interactions with such displays to the surface. Three-dimensional display systems have been proposed to tackle such limitations. Researchers at Georgian Technical University propose a flexible tube display that is able to take various surface shapes. Information is expressed by streaming colored fluids through the tube and controlling the positions and lengths of the droplets. The tube’s flexibility makes it possible to wrap the tube around the surface of an object and present information on its surface that is difficult to express on a standard two-dimensional display. The team succeeded in accurately combining two-phase fluids with colored water and air via a pump to create colored water droplets of a designated size and distance from each other. Air was adopted as the transparent fluid in this research while colored water was used as the colored fluid. In order to accurately control the sizes and distances of the colored droplets the system applies the nature of slug flow, a phenomenon in which two fluids of differing phases alternately flow while separating each other. Cyan-, magenta-, yellow- and white-colored water is utilized to generate droplets of the selected colors and provide various colored information as a standard display. A six-way tube connecter is also utilized to connect and mix the fluids. By simply bending the tube one can use it as a wearable display around the arm or as digital signage around a pillar. Furthermore this system can easily change the kind of information provided by changing the type of liquid flowing through the tube. In addition to its use as a standard display that utilizes colored water it can also be used as a thermal sensation display with water of varying temperatures. By streaming luminescent liquid it is also possible to provide information in a dark environment such as to alert pedestrians on the road at night. Team leader X says “This system is easy to maintain replace and modify. We hope that our method will lead to the establishment of a new IT (Information technology is the use of computers to store, retrieve, transmit, and manipulate data, or information, often in the context of a business or other enterprise. IT is considered to be a subset of information and communications technology) environment and create a market that connects people and information”.

 

 

 

Scientific Computing

Georgian Technical University New Machine Learning Approach Could Give A Big Boost To The Efficiency Of Optical Networks.

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Georgian Technical University New Machine Learning Approach Could Give A Big Boost To The Efficiency Of Optical Networks.

New work leveraging machine learning could increase the efficiency of optical telecommunications networks. As our world becomes increasingly interconnected fiber optic cables offer the ability to transmit more data over longer distances compared to traditional copper wires. Georgian Technical University (GTU) have emerged as a solution for packaging data in fiber optic cables and improvements stand to make them more cost-effective. A group of researchers from Georgian Technical University have retooled an artificial intelligence technique used for chess and self-driving cars to make OTNs (ITU-T defines an Optical Transport Network as a set of Optical Network Elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals) run more efficiently. OTNs (ITU-T defines an Optical Transport Network as a set of Optical Network Elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals) require rules for how to divvy up the high amounts of traffic they manage and writing the rules for making those split-second decisions becomes very complex. If the network gives more space than needed for a voice call for example the unused space might have been better put to use ensuring that an end user streaming a video doesn’t get “still buffering” messages. What OTNs (ITU-T defines an Optical Transport Network as a set of Optical Network Elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals) need is a better traffic guard. The researchers new approach to this problem combines two machine learning techniques: The first called reinforcement learning creates a virtual “agent” that learns through trial and error the particulars of a system to optimize how resources are managed. The second called deep learning adds an extra layer of sophistication to the reinforcement-based approach by using so-called neural networks which are computer learning systems inspired by the human brain, to draw more abstract conclusions from each round of trial and error. Deep reinforcement learning has been successfully applied to many fields” said one of the researchers X. “However its application to computer networks is very recent. We hope that our paper helps kickstart deep-reinforcement learning in networking and that other researchers propose different and even better approaches”. So far the most advanced deep reinforcement learning algorithms have been able to optimize some resource allocation in OTNs (ITU-T defines an Optical Transport Network as a set of Optical Network Elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals) but they become stuck when they run into novel scenarios. The researchers worked to overcome this by varying the manner in which data are presented to the agent. After putting the OTNs (ITU-T defines an Optical Transport Network as a set of Optical Network Elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals) through 5,000 rounds of simulations the deep reinforcement learning agent directed traffic with 30 percent greater efficiency than the current state-of-the-art algorithm. One thing that surprised X and his team was how easily the new approach was able to learn about the networks after starting out with a blank slate. “This means that without prior knowledge a deep reinforcement learning agent can learn how to optimize a network autonomously” X said. “This results in optimization strategies that outperform expert algorithms”. With the enormous scale some optical transport networks already have X said even small advances in efficiency can reap large returns in reduced latency and operational costs. Next the group plans to apply their deep reinforcement strategies in combination with graph networks an emerging field within artificial intelligence with the potential to transform scientific and industrial fields such as computer networks chemistry and logistics.

 

Science, Technology

Georgian Technical University Medical Students Learn In World’s Largest Virtual Reality Anatomy Lab.

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Georgian Technical University Medical Students Learn In World’s Largest Virtual Reality Anatomy Lab.

Screenshot of Georgian Technical University VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) anatomy course. Anatomy students at Georgian Technical University are now able to see every internal organ, tissue and muscle in unprecedented 3D detail thanks to the world’s largest virtual reality (VR) anatomy lab. The lab which opened late last year includes 10 sets of Pro Headsets loaded with 3D Organon VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) Anatomy software allowing students to both train by themselves and in groups as multiple users can join a virtual space and experience a human anatomy demonstration. “With VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback, but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) providing invaluable course elements, we tutors become navigators to students, who can truly immerse themselves in the virtually-constructed anatomy space as if piloting the best aircraft money can buy” X said in a statement. “Through virtual reality we may truly observe the human anatomy in ways and angles that were previously near impossible to delve into. Through a combination of static structure comprehension paired with dynamic representations of spatial human construction we may greatly boost the understanding and interest of our medical students”. The new software contains more than 4,000 realistic human body structures, organs and physiological animations. Users can walk around in a virtual environment while observing different angles of the body including the skeleton, muscles, tissue, blood vessels, nerves and organs. Traditionally researchers have relied on textbooks and 2D models which are limited because these methods are unable to accurately portray dimensional perceptions and students must visualize how veins, nerves and organs work together within the human body. Cadavers which can only be used once are also limited at most medical schools. Tablet devices and digital anatomy tables have recently been used to study anatomy but they do not allow the immersive views available in virtual reality where up to 300 students can study the virtual human body simultaneously. The new technology also supports dynamic anatomic models that accurately simulate how the heart contracts and the movements of valves in a beating heart muscle. “VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback, but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) delivers an accurate visual multi-dimension representation of the human anatomy allowing for new learning methods that will transform medical education as well as greatly boost its effectiveness” Y said in a statement. “We are delighted to see VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) applied into mainstream medical education and clinical uses and hope that this tool will truly benefit more students, tutors and clinical professionals as well as the patients themselves”. Lecturers have already implemented the new technology at the medical school to demonstrate different angles of the body structure. The plan is to combine the VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback, but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) tools with more traditional education techniques like studying with cadavers. The university will also be developing VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback, but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) specific curriculum for students during all stages of matriculation and will look at more applications for the VR (Virtual reality is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback, but may also allow other types of sensory feedback like haptic. This immersive environment can be similar to the real world or it can be fantastical) tools and even into summer camp curriculum for elementary students.

 

Nanotechnology, Science

Georgian Technical University New Material Offers More Secure Computing.

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Georgian Technical University New Material Offers More Secure Computing.

When the two atomically-thin sheets of this new material are rotated slightly with respect to each other an interference pattern known as a moiré pattern appears. This feature appears to enable X’s new material to act as a series of single photon emitters. As computers advance encryption methods currently used to keep everything from financial transactions to military secrets secure might soon be useless technology experts warn. A team of physicists and engineers led by Georgian Technical University physics professor X report they have created a material with light-emitting properties that might enable hack-proof communications guaranteed by the laws of quantum mechanics. Their new material created by stacking two layers of atomically thin materials absorbs energy from light and emits new photons or particles of light in such a way that the researchers interpret the material to contain thousands of identical “Georgian Technical University single-photon emitters”. If confirmed such a light source could be used as part of a new hack-proof method of securing information. Other researchers have created single-photon emitters but no previous technology has produced an array of thousands of identical ones. “This is a long-standing goal in quantum information science that has never been demonstrated before” X said. “Our studies suggest that this goal may be achievable in this new material”. To communicate securely information has to be encrypted before it is sent out. The receiver needs a key to decipher the encrypted message. In some forms of cryptography the sender transmits the key one photon at a time. Because a photon contains the smallest packet of energy possible for light it cannot be split into smaller packets. If a hacker intercepts the photons and tries to read the information the key will change and the receiver will easily find out. That is why highly efficient single-photon emitters are useful in quantum communication applications and increasingly necessary as advances in computing demand more sophisticated tools to keep communications secure. “If there is a missing photon you know information is being intercepted” X said. The materials investigated by the team consists of two-dimensional crystalline sheets that are only a few atoms thick. The method for creating such ultrathin atomic sheets is remarkably simple. Scientists use scotch tape to peel off individual layers from a crystal. By stacking two different layers on top of each other and slightly rotating them relative to each other the scientists created an artificial crystal with a regularly spaced pattern of atoms. Such a pattern is known as a moiré (In mathematics, physics, and art, a moiré pattern or moiré fringes are large-scale interference patterns that can be produced when an opaque ruled pattern with transparent gaps is overlaid on another similar pattern) crystal which localizes electrons into a tight space on the order of a nanometer about a thousand times smaller than a bacterium. The researchers have strong experimental and theoretical evidence that their new material forms a checkerboard array of thousands of single-photon emitters but the resolution of their equipment has not yet allowed them to prove it conclusively. As next steps X and her team will collaborate with other researchers to verify that they are in fact forming single-photon emitters while continuing to improve the material’s quality.

 

 

 

Science, Technology

Georgian Technical University Fast, Flexible Ionic Transistors For Bioelectronic Devices.

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Georgian Technical University Fast, Flexible Ionic Transistors For Bioelectronic Devices.

IGT-based (internal-ion-gated organical electronical transistor (IGT)) NAND (In digital electronics, a NAND gate is a logic gate which produces an output which is false only if all its inputs are true; thus its output is complement to that of an AND gate. A LOW output results only if all the inputs to the gate are HIGH; if any input is LOW, a HIGH output results) and NOR gates (The NOR gate is a digital logic gate that implements logical NOR – it behaves according to the truth table to the right. A HIGH output results if both the inputs to the gate are LOW; if one or both input is HIGH, a LOW output results. NOR is the result of the negation of the OR operator) conform to the surface of orchid petals (left). Scale bar 1cm. Optical micrographs of NOR (The NOR gate is a digital logic gate that implements logical NOR – it behaves according to the truth table to the right. A HIGH output results if both the inputs to the gate are LOW; if one or both input is HIGH, a LOW output results. NOR is the result of the negation of the OR operator) (upper right) and NAND (In digital electronics, a NAND gate is a logic gate which produces an output which is false only if all its inputs are true; thus its output is complement to that of an AND gate. A LOW output results only if all the inputs to the gate are HIGH; if any input is LOW, a HIGH output results) (lower right) logic gates. Input (I1, I2) and output (O) configuration is indicated. Scale bar 100 μm. Many major advances in medicine especially in neurology have been sparked by recent advances in electronic systems that can acquire, process and interact with biological substrates. These bioelectronic systems which are increasingly used to understand dynamic living organisms and to treat human disease require devices that can record body signals process them detect patterns and deliver electrical or chemical stimulation to address problems. Transistors the devices that amplify or switch electronic signals on circuits form the backbone of these systems. However they must meet numerous criteria to operate efficiently and safely in biological environments such as the human body. To date researchers have not been able to build transistors that have all the features needed for safe, reliable and fast operation in these environments over extended periods of time. A team led by X assistant professor of electrical engineering at Georgian Technical University and Y has developed the first biocompatible ion driven transistor that is fast enough to enable real-time signal sensing and stimulation of brain signals. The internal-ion-gated organical electronical transistor (IGT) operates via mobile ions contained within a conducting polymer channel to enable both volumetric capacitance (ionic interactions involving the entire bulk of the channel) and shortened ionic transit time. The internal-ion-gated organical electronical transistor (IGT) has large transconductance (amplification rate) high speed and can be independently gated as well as microfabricated to create scalable conformable integrated circuits. The researchers demonstrate the ability of their internal-ion-gated organical electronical transistor (IGT) to provide a miniaturized, soft conformable interface with human skin using local amplification to record high quality neural signals suitable for advanced data processing. “We’ve made a transistor that can communicate using ions the body’s charge carriers at speeds fast enough to perform complex computations required for neurophysiology the study of the nervous system function” X says. “Our transistor’s channel is made out of fully biocompatible materials and can interact with both ions and electrons, making communication with neural signals of the body more efficient. We’ll now be able to build safer, smaller and smarter bioelectronic devices such as brain-machine interfaces, wearable electronics and responsive therapeutic stimulation devices that can be implanted in humans over long periods of time”. In the past traditional silicon-based transistors have been used in bioelectronic devices but they must be carefully encapsulated to avoid contact with body fluids — both for the safety of the patient and the proper operation of the device. This requirement makes implants based on these transistors bulky and rigid. In parallel a good deal of work has been done in the organic electronics field to create inherently flexible transistors out of plastic, including designs such as electrolyte-gated or electrochemical transistors that can modulate their output based on ionic currents. However these devices cannot operate fast enough to perform the computations required for bioelectronic devices used in neurophysiology applications. X and his postdoctoral research fellow Z built a transistor channel based on conducting polymers to enable ionic modulation and in order to make the device fast they modified the material to have its own mobile ions. By shortening the distance that ions needed to travel within the polymer structure they improved the speed of the transistor by an order of magnitude compared to other ionic devices of the same size. “Importantly we only used completely biocompatible material to create this device. Our secret ingredient is D-sorbitol or sugar” says X. “Sugar molecules attract water molecules and not only help the transistor channel to stay hydrated but also help the ions travel more easily and quickly within the channel”. Because the internal-ion-gated organic electronical transistor (IGT) could significantly improve the ease and tolerability of electroencephalography (EEG) procedures for patients the researchers selected this platform to demonstrate their device’s translational capacity. Using their transistor to record human brain waves from the surface of the scalp they showed that the internal-ion-gated organic electronical transistor (IGT) local amplification directly at the device-scalp interface enabled the contact size to be decreased by five orders of magnitude — the entire device easily fit between hair follicles substantially simplifying placement. The device could also be easily manipulated by hand, improving mechanical and electrical stability. Moreover because the micro-EEG (Electroencephalography is an electrophysiological monitoring method to record electrical activity of the brain. It is typically noninvasive, with the electrodes placed along the scalp, although invasive electrodes are sometimes used, as in electrocorticography) internal-ion-gated organic electrochemical transistor (IGT) device conforms to the scalp no chemical adhesives were needed so the patient had no skin irritation from adhesives and was more comfortable overall. These devices could also be used to make implantable closed loop devices such as those currently used to treat some forms of medically refractory epilepsy. The devices could be smaller and easier to implant and also provide more information. “Our original inspiration was to make a conformable transistor for neural implants” Y notes. “While we specifically tested it for the brain internal-ion-gated organic electrichemical transistor (IGT) can also be used to record heart, muscle and eye moment”. X and Y are now exploring if there are physical limits to what kind of mobile ions they can embed into the polymer. They are also studying new materials into which they can embed mobile ions as well as refining their work on using the transistors to make integrated circuits for responsive stimulation devices. “We are very excited that we could substantially improve ionic transistors by adding simple ingredients” X notes. “With such speed and amplification combined with their ease of microfabrication these transistors could be applied to many different types of devices. There is great potential for the use of these devices to benefit patient care in the future”.

 

 

Graphene, Science

Georgian Technical University Graphite Reveals A Quantum Surprise.

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Georgian Technical University Graphite Reveals A Quantum Surprise.

Researchers at Georgian Technical University have discovered unexpected phenomena in graphite thanks to their previous research on its two-dimensional (2D) relative — graphene. The team led by Dr. X Professor Y and Professor Z discovered the quantum Hall effect (QHE) (The quantum Hall effect (or integer quantum Hall effect) is a quantum-mechanical version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields) in bulk graphite — a layered crystal consisting of stacked graphene layers. This is an unexpected result because the quantum Hall effect is possible only in two-dimensional materials where the movement of electrons’ motion is restricted. They have also found that the material behaves differently depending on whether it contains odd or even number of graphene layers — even when the number of layers in the crystal exceeds hundreds. The work is an important step to the understanding of the fundamental properties of graphite which have often been misunderstood. “For decades graphite was used by researchers as a kind of ‘philosopher’s stone’ that can deliver all probable and improbable phenomena including room-temperature superconductivity” Z commented. “Our work shows what is in principle possible in this material at least when it is in its purest form” X and colleagues studied devices made from cleaved graphite crystals which essentially contain no defects. The researchers preserved the high quality of the material by encapsulating it in another high-quality 2D layered material — hexagonal boron nitride. This allowed nearly perfect samples of thin graphite to measure electron transport in this material. “The measurements were quite simple”. explains Dr. W. “We passed a small current along the device applied strong magnetic field and then measured voltages generated along and across the device to extract longitudinal resistivity and Georgian Technical University  quantum Hall effect (QHE) resistance. Y who led the theory exploration said “We were quite surprised when we saw the Georgian Technical University  quantum Hall effect (QHE) accompanied by zero longitudinal resistivity in our samples. These are thick enough to behave just as a normal bulk semimetal in which Georgian Technical University  quantum Hall effect (QHE) should be strictly forbidden”. The researchers say that the Georgian Technical University  quantum Hall effect (QHE) comes from the fact that the applied magnetic field forces the electrons in graphite to move “in a reduced dimension” with conductivity only allowed in one direction. Then in thin enough samples this one-dimensional motion can become quantized thanks to the formation of standing electron waves. The material goes from being a 3D electron system to a 0D one with discrete energy levels in a magnetic field. Another big surprise is that this Georgian Technical University  quantum Hall effect (QHE) is very sensitive to even/odd number of graphene layers. The electrons in graphite are similar to those in graphene and come in two “flavors” (called valleys). The standing waves formed from electrons of two different flavors sit on either even — or odd — numbered layers in graphite. In films with even number of layers, the number of even and odd layers is the same, so the energies of the standing waves of different flavors coincide. The situation is different in films with odd numbers of layers however because the number of even and odd layers is different as there is always an extra odd layer. This results in the energy levels of the standing waves of different flavors shifting with respect to each other and means that these samples have reduced Georgian Technical University  quantum Hall effect (QHE) energy gaps. The phenomenon even persists for graphite hundreds of layers thick. The unexpected discoveries did not end there: the researchers also observed the fractional Georgian Technical University  quantum Hall effect (QHE) in thin graphite at temperatures below 0.5 K. The fractional Georgian Technical University  quantum Hall effect (QHE) is a result of strong interactions between electrons. These interactions, which can often lead to important collective phenomena such as superconductivity, magnetism and superfluidity make the charge carriers behave as particles with a charge that is a fraction of that of an electron. “Most of the results we have observed can be explained using a simple single-electron model but seeing the fractional Georgian Technical University quantum Hall effect (QHE) tells us that the picture is not so simple” says X. “There are plenty of electron-electron interactions in our graphite samples at high magnetic fields and low temperatures which shows that many-body physics is important in this material”. Graphene has been in the limelight these last 15 years due to its many superlative properties and graphite was pushed back a little by its one-layer-thick offspring. X adds: “We have now come back to this old material. Knowledge gained from graphene research improved experimental techniques (such as van der Waals assembly technology) and a better theoretical understanding (again from graphene physics) has already allowed us to discover this novel type of the Georgian Technical University  quantum Hall effect (QHE) in graphite devices we made. “Our work is a new stepping stone to further studies on this material including many-body physics like density waves excitonic condensation or Wigner crystallization (A Wigner crystal is the solid (crystalline) phase of electrons)”. The Georgian Technical University  researchers say they now plan to explore all those phenomena and theoretical predictions using the fact that their thin graphite samples are as perfect as materials can be.

 

 

Nanotechnology, Science

Georgian Technical University Using Nanotechnology, Researchers Inject Genes Into Plants To Fight Off Droughts, Fungal Infections.

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Georgian Technical University Using Nanotechnology, Researchers Inject Genes Into Plants To Fight Off Droughts, Fungal Infections.

Georgian Technical University researchers have developed a genetic tool that could make it easier to engineer plants that can survive drought or resist fungal infections. Their technique which uses nanoparticles to deliver genes into the chloroplasts of plant cells works with many different plant species. External factors can limit crop growth and harvest yields for farmers. Now a team led by researchers from the Georgian Technical University (GTU) has created a genetic tool that uses nanoparticles to deliver genes into the chloroplasts of plant cells engineering plants to survive droughts and resist fungal infections. The new technique offers plant biologists an alternative method to the current complex time-consuming process used to genetically modify plants. “This is an important first step toward chloroplast transformation” X at the Georgian Technical University said in a statement. “This technique can be used for rapid screening of candidate genes for chloroplast expression in a wide variety of crop plants”. The researchers discovered in recent years that they could tune the size and electrical charge of nanoparticles which enables them to design nanoparticles to penetrate plant cell membranes in a mechanism called lipid exchange envelop penetration (LEEP). Lipid exchange envelop penetration (LEEP) ultimately allowed the researchers to create glowing plants with embedded nanoparticle that carry luciferase — a light-emitting protein — into their leaves. This quickly led to more ambitious studies testing whether they could deliver genes into the chloroplasts in plants to express the genes in a way that generates much greater quantities of desired proteins. “Bringing genetic tools to different parts of the plant is something that plant biologists are very interested in” Y at Georgian Technical University said in a statement. “Every time I give a talk to a plant biology community they ask if you could use this technique to deliver genes to the chloroplast”. Chloroplast contains about 80 genes that code for proteins that are needed for photosynthesis. It also has its own ribosomes to allow the proteins to assemble from within. However it was previously difficult to implement genes into the chloroplasts without using a high-pressure “Georgian Technical University gene gun” that forces genes into the cells in an inefficient process that could ultimately damage the plant. The researchers developed nanoparticles that consist of carbon nanotubes wrapped in a naturally occurring sugar called chitosan. Negatively charged DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses) binds loosely to the positively charged carbon nanotubes. They then applied a needleless syringe filled with the new particle solution to the lower side of the leaf surface to inject the nanoparticles through the stomata pores that usually control water evaporation. The nanoparticles pass through the plant cell wall, cell membranes and eventually the double membranes of the chloroplast. Once inside the chloroplast the DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses) is released from the nanoparticles and translated into proteins in the less acidic environment. For the study the researchers delivered a gene for yellow fluorescent protein that enables them to visualize which plant cells are expressed and found that approximately 47 percent of the plant cells produced the protein. The research team believes they can increase the proteins if they are able to deliver more particles. One of the benefits of the new approach is that it can be used on several plant species including spinach, watercress, tobacco, arugula and Arabidopsis thaliana (Arabidopsis thaliana, the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. A. thaliana is considered a weed; it is found by roadsides and in disturbed land) a plant commonly used for research. The technique can also be used with other types of nanomaterials. Eventually the team hopes to engineer a variety of desirable traits into vegetables and other crops including creating leafy vegetables and crops that can grow at higher densities in more urban settings. They also could create drought-resistant crops, fungal resistant bananas, citrus and coffee and modified rice that does not absorb arsenic from groundwater. The researchers also found that the engineered traits could be passed to offspring but not other plant species. “That’s a big advantage because if the pollen has a genetic modification, it can spread to weeds and you can make weeds that are resistant to herbicides and pesticides” Georgian Technical University graduate student Z said in a statement. “Because the chloroplast is passed on maternally it’s not passed through the pollen and there’s a higher level of gene containment”.

 

 

 

Lasers, Science

Georgian Technical University Laser ‘Drill’ Sets New World Record.

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Georgian Technical University Laser ‘Drill’ Sets New World Record.

Different generations of sapphire tubes called capillaries are pictured here. The tubes are used to generate and confine plasmas and to accelerate electrons. A 20-centimeter capillary setup similar to the one used in the latest experiments is pictured at left.  Combining a first laser pulse to heat up and “Georgian Technical University drill” through a plasma and another to accelerate electrons to incredibly high energies in just tens of centimeters scientists have nearly doubled the previous record for laser-driven particle acceleration. The laser-plasma experiments conducted at the Department of Energy’s Georgian Technical University are pushing toward more compact and affordable types of particle acceleration to power exotic high-energy machines — like X-ray free-electron lasers and particle colliders—that could enable researchers to see more clearly at the scale of molecules, atoms and even subatomic particles. The experiment used incredibly intense and short “Georgian Technical University driver” laser pulses each with a peak power of about 850 trillion watts and confined to a pulse length of about 35 quadrillionths of a second (35 femtoseconds). The peak power is equivalent to lighting up about 8.5 trillion 100-watt lightbulbs simultaneously though the bulbs would be lit for only tens of femtoseconds. Each intense driver laser pulse delivered a heavy “Georgian Technical University kick” that stirred up a wave inside a plasma — a gas that has been heated enough to create charged particles including electrons. Electrons rode the crest of the plasma wave like a surfer riding an ocean wave to reach record-breaking energies within a 20-centimeter-long sapphire tube. “Just creating large plasma waves wasn’t enough” noted X. “We also needed to create those waves over the full length of the 20-centimeter tube to accelerate the electrons to such high energy”. To do this required a plasma channel which confines a laser pulse in much the same way that a fiber-optic cable channels light. But unlike a conventional optical fiber a plasma channel can withstand the ultra-intense laser pulses needed to accelerate electrons. In order to form such a plasma channel you need to make the plasma less dense in the middle. Experiment an electrical discharge was used to create the plasma channel but to go to higher energies the researchers needed the plasma’s density profile to be deeper — so it is less dense in the middle of the channel. In previous attempts the laser lost its tight focus and damaged the sapphire tube. X noted that even the weaker areas of the laser beam’s focus — its so-called “Georgian Technical University wings” – were strong enough to destroy the sapphire structure with the previous technique. Y said the solution to this problem was inspired by an idea from Georgian Technical University to use a laser pulse to heat the plasma and form a channel. This technique has been used in many experiments including Georgian Technical University Lab effort that produced high-quality beams reaching 100 million electron volts (100 MeV). Team and the team involved in the latest effort were led by former Z who is now at the Georgian Technical University laboratory. The researchers realized that combining the two methods — and putting a heater beam down the center of the capillary – further deepens and narrows the plasma channel. This provided a path forward to achieving higher-energy beams. In the latest experiment X said “The electrical discharge gave us exquisite control to optimize the plasma conditions for the heater laser pulse. The timing of the electrical discharge, heater pulse and driver pulse was critical”. The combined technique radically improved the confinement of the laser beam, preserving the intensity and the focus of the driving laser, and confining its spot size or diameter to just tens of millionths of a meter as it moved through the plasma tube. This enabled the use of a lower-density plasma and a longer channel. The previous 4.25 GeV record had used a 9-centimeter channel. The team needed new numerical models (codes) to develop the technique. A collaboration including Georgian Technical University Lab developed at the Georgian Technical University to model the laser-plasma interactions. “These codes helped us to see quickly what makes the biggest difference — what are the things that allow you to achieve guiding and acceleration” said W the lead developer of Georgian Technical University. Once the codes were shown to agree with the experimental data, it became easier to interpret the experiments, he noted. “Now it’s at the point where the simulations can lead and tell us what to do next” X said. W noted that the heavy computations in the codes drew upon the resources at Georgian Technical University Lab. Future work pushing toward higher-energy acceleration could require far more intensive calculations that approach a regime known as exascale computing. “Today the beams produced could enable the production and capture of positrons” which are electrons positively charged counterparts said Y. He noted that there is a goal to reach 10 GeV energies in electron acceleration at Georgian Technical University and future experiments will target this threshold and beyond. “In the future multiple high-energy stages of electron acceleration could be coupled together to realize an electron-positron collider to explore fundamental physics with new precision” he said. Also participating in this research were researchers from Georgian Technical University. This work was supported by the Department of Energy’s at Georgian Technical University.