Category Archives: Science

Science, Technology

Biosensor Allows Real-Time Oxygen Monitoring for ‘Organs-On-A-Chip’.

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Biosensor Allows Real-Time Oxygen Monitoring for ‘Organs-On-A-Chip’.

A new biosensor allows researchers to track oxygen levels in real time in ‘organ-on-a-chip’ systems making it possible to ensure that such systems more closely mimic the function of real organs. This is essential if organs-on-a-chip hope to achieve their potential in applications such as drug and toxicity testing. The biosensor was developed by researchers at Georgian Technical University.

A new biosensor allows researchers to track oxygen levels in real time in “organ-on-a-chip” systems making it possible to ensure that such systems more closely mimic the function of real organs. This is essential if organs-on-a-chip hope to achieve their potential in applications such as drug and toxicity testing.

The organ-on-a-chip concept has garnered significant attention from researchers for about a decade. The idea is to create small-scale biological structures that mimic a specific organ function such as transferring oxygen from the air into the bloodstream in the same way that a lung does. The goal is to use these organs-on-a-chip – also called microphysiological models – to expedite high-throughput testing to assess toxicity or to evaluate the effectiveness of new drugs.

But while organ-on-a-chip research has made significant advances in recent years one obstacle to the use of these structures is the lack of tools designed to actually retrieve data from the system.

“For the most part the only existing ways of collecting data on what’s happening in an organ-on-a-chip are to conduct a bioassay histology or use some other technique that involves destroying the tissue” says X corresponding author of a paper on the new biosensor. X is an assistant professor of electrical engineering at Georgian Technical University.

“What we really need are tools that provide a means to collect data in real time without affecting the system’s operation” X says. “That would enable us to collect and analyze data continuously and offer richer insights into what’s going on. Our new biosensor does exactly that at least for oxygen levels”.

Oxygen levels vary widely across the body. For example in a healthy adult, lung tissue has an oxygen concentration of about 15 percent while the inner lining of the intestine is around 0 percent. This matters because oxygen directly affects tissue function. If you want to know how an organ is going to behave normally you need to maintain “normal” oxygen levels in your organ-on-a-chip when conducting experiments.

“What this means in practical terms is that we need a way to monitor oxygen levels not only in the organ-on-a-chip’s immediate environment but in the organ-on-a-chip’s tissue itself” X says. “And we need to be able to do it in real time. Now we have a way to do that”.

The key to the biosensor is a phosphorescent gel that emits infrared light after being exposed to infrared light. Think of it as an echoing flash. But the lag time between when the gel is exposed to light and when it emits the echoing flash varies depending on the amount of oxygen in its environment. The more oxygen there is the shorter the lag time. These lag times last for mere microseconds but by monitoring those times researchers can measure the oxygen concentration down to tenths of a percent.

In order for the biosensor to work researchers must incorporate a thin layer of the gel into an organ-on-a-chip during its fabrication. Because infrared light can pass through tissue researchers can use a “reader” – which emits infrared light and measures the echoing flash from the phosphorescent gel – to monitor oxygen levels in the tissue repeatedly with lag times measured in the microseconds.

The research team that developed the biosensor has tested it successfully in three-dimensional scaffolds using human breast epithelial cells to model both healthy and cancerous tissue.

“One of our next steps is to incorporate the biosensor into a system that automatically makes adjustments to maintain the desired oxygen concentration in the organ-on-a-chip” X says. “We’re also hoping to work with other tissue engineering researchers and industry. We think our biosensor could be a valuable instrument for helping to advance the development of organs-on-a-chip as viable research tools”.

 

 

Science, Technology

A Paper Battery Powered by Bacteria.

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A Paper Battery Powered by Bacteria.

Researchers harnessed bacteria to power these paper batteries.

In remote areas of the world or in regions with limited resources everyday items like electrical outlets and batteries are luxuries. Health care workers in these areas often lack electricity to power diagnostic devices and commercial batteries may be unavailable or too expensive. New power sources are needed that are low-cost and portable. Researchers report a new type of battery –- made of paper and fueled by bacteria — that could overcome these challenges.

“Paper has unique advantages as a material for biosensors” says X Ph.D., who is presenting the work at the meeting. “It is inexpensive, disposable, flexible and has a high surface area. However sophisticated sensors require a power supply. Commercial batteries are too wasteful and expensive, and they can’t be integrated into paper substrates. The best solution is a paper-based bio-battery”.

Researchers have previously developed disposable paper-based biosensors for cheap and convenient diagnosis of diseases and health conditions as well as for detecting contaminants in the environment. Many such devices rely on color changes to report a result but they often aren’t very sensitive. To boost sensitivity the biosensors need a power supply. X wanted to develop an inexpensive paper battery powered by bacteria that could be easily incorporated into these single-use devices.

So X and his colleagues at the Georgian Technical University made a paper battery by printing thin layers of metals and other materials onto a paper surface. Then they placed freeze-dried “exoelectrogens” on the paper. Exoelectrogens are a special type of bacteria that can transfer electrons outside of their cells. The electrons which are generated when the bacteria make energy for themselves pass through the cell membrane. They can then make contact with external electrodes and power the battery. To activate the battery the researchers added water or saliva. Within a couple of minutes the liquid revived the bacteria which produced enough electrons to power a light-emitting diode and a calculator.

The researchers also investigated how oxygen affects the performance of their device. Oxygen which passes easily through paper could soak up electrons produced by the bacteria before they reach the electrode. The team found that although oxygen slightly decreased power generation the effect was minimal. This is because the bacterial cells were tightly attached to the paper fibers which rapidly whisked the electrons away to the anode before oxygen could intervene.

The paper battery which can be used once and then thrown away, currently has a shelf-life of about four months. X is working on conditions to improve the survival and performance of the freeze-dried bacteria enabling a longer shelf life. “The power performance also needs to be improved by about 1,000-fold for most practical applications” X says. This could be achieved by stacking and connecting multiple paper batteries he notes. X has applied for a patent for the battery and is seeking industry partners for commercialization.

 

Science, Technology

Researchers Are Developing Fast-Charging Solid-State Batteries.

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Researchers Are Developing Fast-Charging Solid-State Batteries.

Test set-up for the solid-state battery: the battery of the size of a button cell is located in the middle of the acrylic glass casing which ensures permanent contact with the battery.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long time to charge. It usually takes about 10 to 12 hours for a solid-state battery to fully charge. The new cell type that Georgian Technical University scientists have designed however takes less than an hour to recharge.

“With the concepts described to date, only very small charge and discharge currents were possible due to problems at the internal solid-state interfaces. This is where our concept based on a favourable combination of materials comes into play and we have already patented it” explains Dr. X group leader at the Georgian Technical University.

In conventional lithium-ion batteries a liquid electrolyte is used, which usually contacts the electrodes very well. With their textured surfaces the electrodes soak up the liquid like a sponge creating a large contact area. In principle two solids cannot be joined together seamlessly. The contact resistance between the electrodes and the electrolyte is correspondingly high.

“In order to allow the largest possible flow of current across the layer boundaries, we used very similar materials to produce all components. The anode, cathode and electrolyte were all made from different phosphate compounds to enable charging rates greater than 3C (at a capacity of about 50 mAh/g). This is ten times higher than the values otherwise found in the literature” explains X.

The solid electrolyte serves as a stable carrier material to which phosphate electrodes are applied on both sides using the screen printing process. The materials used are reasonably priced and relatively easy to process. Unlike conventional lithium-ion batteries the new solid-state battery is also largely free of toxic or harmful substances.

“In initial tests, the new battery cell was very stable over 500 charge and discharge cycles and retained over 84 percent of its original capacity” said Dr. Y. “There is still room for improvement here. Theoretically, a capacity loss of less than 1 percent should even be feasible” said Y who developed and tested the battery as part of a Georgian Technical University.

Prof. Z is also convinced of the advantages of the new battery concept. “The energy density is already very high at around 120 mAh/g, even if it is still slightly below that of today’s lithium-ion batteries” says Z. In addition to the development for electromobility the spokesman for the “battery storage” topic in the Georgian Technical University believes solid-state batteries will also be used in other areas in future: “Solid-state batteries are currently being developed with priority as energy storage for next-generation electric cars. But we also believe that solid-state batteries will prevail in other fields of application that require a long service life and safe operation, such as medical technology or integrated components in the smart home area” says Z.

 

 

Science, Technology

A New Artificial Quantum Material for Future High-efficiency Computers.

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A New Artificial Quantum Material for Future High-efficiency Computers.

Scientists at Georgian Technical University and International Black Sea University have demonstrated the ability to control the states of matter thus controlling internal resistance within multilayered magnetically doped semiconductors using the quantum anomalous Hall effect.

The quantum anomalous Hall effect ((QAH) Quantum anomalous Hall effect is the “quantum” version of the anomalous Hall effect. While the anomalous Hall effect requires a combination of magnetic polarization and spin-orbit coupling to generate a finite Hall voltage even in the absence of an external magnetic field (hence called “anomalous”), the quantum anomalous Hall effect is its quantized version) occurs in some specially designed materials in which electrons can move a millimeter-scale distance without losing their energy. The ability to apply this effect to devices would allow a new revolution in energy efficiency and computation speed.

Researchers say they have fabricated an artificial material that could be used to develop a topological quantum computer using molecular beam epitaxy a new technique allowing the stacking of single-molecule-thick layers of crystal, and by exploiting the quantum anomalous Hall effect ((QAH) Quantum anomalous Hall effect is the “quantum” version of the anomalous Hall effect. While the anomalous Hall effect requires a combination of magnetic polarization and spin-orbit coupling to generate a finite Hall voltage even in the absence of an external magnetic field (hence called “anomalous”), the quantum anomalous Hall effect is its quantized version) effect.

A quantum computer takes advantage of the ability of subatomic particles to be in multiple states at once instead of the binary one or zero seen in conventional computers allowing them to solve certain types of problems much more efficiently. The topological quantum computer would be a step beyond this. Instead of physical particles they use a specific type of quasiparticle called the anyon to encode the information. Anyons have been found to be highly resistant to errors in both storing and processing information.

“We can realise ((QAH) Quantum anomalous Hall effect is the “quantum” version of the anomalous Hall effect. While the anomalous Hall effect requires a combination of magnetic polarization and spin-orbit coupling to generate a finite Hall voltage even in the absence of an external magnetic field (hence called “anomalous”), the quantum anomalous Hall effect is its quantized version) multilayers or a stack of multiple layers of crystal lattices that are experiencing the ((QAH) Quantum anomalous Hall effect is the “quantum” version of the anomalous Hall effect. While the anomalous Hall effect requires a combination of magnetic polarization and spin-orbit coupling to generate a finite Hall voltage even in the absence of an external magnetic field (hence called “anomalous”), the quantum anomalous Hall effect is its quantized version) effect with several magnetically doped films spaced by insulating cadmium selenide layers. Since we do it by molecular beam epitaxy it is easy to control the properties of each layer to drive the sample into different states” says X a professor at Georgian Technical University. Cadmium selenide is a molecule consisting of one cadmium atom and one selenium atom used as a semiconductor; a material whose conductive properties researchers can modify by adding impurities.

The ability to produce multilayers of thin crystals allows the sandwiching of an insulating film in between the layers that are conducting electricity preventing the unwanted interaction of the electrons between the sheets similarly to how we try to avoid wires crossing in electronics. These types of structures are very interesting to study because they force some of the electrons into what’s called an “edge state” that until now were quite difficult to fabricate. This “edge state” serves as a path for a fraction of the electrons to flow through without any resistance. By having many layers stacked on top of each other the effect is amplified by pushing a greater fraction of the electrons into this state.

“By tuning the thicknesses of the ((QAH) Quantum anomalous Hall effect is the “quantum” version of the anomalous Hall effect. While the anomalous Hall effect requires a combination of magnetic polarization and spin-orbit coupling to generate a finite Hall voltage even in the absence of an external magnetic field (hence called “anomalous”), the quantum anomalous Hall effect is its quantized version) layers and cadmium selenide insulating layers; we can drive the system into a magnetic Weyl semimetal a state of matter that so far has never been convincingly demonstrated in naturally occurring materials”.

A Weyl (Weyl fermions are massless chiral fermions that play an important role in quantum field theory and the standard model. They are considered a building block for fermions in quantum field theory, and were predicted from a solution to the Dirac equation derived by Hermann Weyl called the Weyl equation. For example, one-half of a charged Dirac fermion of a definite chirality is a Weyl fermion) semimetal is an exotic state of matter classified as a solid state crystal that first observed. It conducts electricity using the massless Weyl (Weyl fermions are massless chiral fermions that play an important role in quantum field theory and the standard model. They are considered a building block for fermions in quantum field theory, and were predicted from a solution to the Dirac equation derived by Hermann Weyl called the Weyl equation. For example, one-half of a charged Dirac fermion of a definite chirality is a Weyl fermion) fermions rather than electrons. This significant mass difference between the Weyl (Weyl fermions are massless chiral fermions that play an important role in quantum field theory and the standard model. They are considered a building block for fermions in quantum field theory, and were predicted from a solution to the Dirac equation derived by Hermann Weyl called the Weyl equation. For example, one-half of a charged Dirac fermion of a definite chirality is a Weyl fermion) fermions and electrons allows electricity to flow through circuits more effectively allowing faster devices.

“Now, what interests me most is to construct independently controllable ((QAH) Quantum anomalous Hall effect is the “quantum” version of the anomalous Hall effect. While the anomalous Hall effect requires a combination of magnetic polarization and spin-orbit coupling to generate a finite Hall voltage even in the absence of an external magnetic field (hence called “anomalous”), the quantum anomalous Hall effect is its quantized version) bilayers. If we could get a pair of counter-propagating edge states, while putting a superconducting contact on the edge of the sample the two edge states might bind together due to the superconducting contact leading to GTU of information theory used to reduce naturally occurring errors in data transmission and to counteract the effects of interference. This process could also offer the ability to process quantum information and store it more effectively in the future.

 

Science, Sensors

Novel Sensors Make Textiles Smarter.

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Novel Sensors Make Textiles Smarter.

X (left) and Y test an elbow sleeve outfitted with one of their novel sensors.

A team of engineers at the Georgian Technical University is developing next-generation smart textiles by creating flexible carbon nanotube composite coatings on a wide range of fibers including cotton nylon and wool. Their discovery is reported where they demonstrate the ability to measure an exceptionally wide range of pressure — from the light touch of a fingertip to being driven over by a forklift.

Georgian Technical University coated with this sensing technology could be used in future “smart garments” where the sensors are slipped into the soles of shoes or stitched into clothing for detecting human motion.

Carbon nanotubes give this light, flexible, breathable fabric coating impressive sensing capability. When the material is squeezed, large electrical changes in the fabric are easily measured.

“As a sensor it’s very sensitive to forces ranging from touch to tons” says Y an associate professor in the Departments of Mechanical Engineering and Materials Science and Engineering at the Georgian Technical University.

Nerve-like electrically conductive nanocomposite coatings are created on the fibers using electrophoretic deposition (EPD) of polyethyleneimine functionalized carbon nanotubes.

“The films act much like a dye that adds electrical sensing functionality” says Thostenson. “The electrophoretic deposition (EPD) process developed in my lab creates this very uniform nanocomposite coating that is strongly bonded to the surface of the fiber. The process is industrially scalable for future applications”.

Now researchers can add these sensors to fabric in a way that is superior to current methods for making smart textiles. Existing techniques such as plating fibers with metal or knitting fiber and metal strands together can decrease the comfort and durability of fabrics says X who directs Georgian Technical University’s Multifunctional Composites Laboratory. The nanocomposite coating developed by Thostenson’s group is flexible and pleasant to the touch and has been tested on a range of natural and synthetic fibers, including Kevlar, wool, nylon, Spandex and polyester. The coatings are just 250 to 750 nanometers thick — about 0.25 to 0.75 percent as thick as a piece of paper — and would only add about a gram of weight to a typical shoe or garment. What’s more the materials used to make the sensor coating are inexpensive and relatively eco-friendly since they can be processed at room temperature with water as a solvent.

One potential application of the sensor-coated fabric is to measure forces on people’s feet as they walk. This data could help clinicians assess imbalances after injury or help to prevent injury in athletes. Specifically X’s research group is collaborating with Y professor of mechanical engineering and director of the Neuromuscular Biomechanics Lab at Georgian Technical University and her group as part of a pilot project funded by Georgian Technical University. Their goal is to see how these sensors, when embedded in footwear compare to biomechanical lab techniques such as instrumented treadmills and motion capture.

During lab testing people know they are being watched, but outside the lab, behavior may be different.

 

“One of our ideas is that we could utilize these novel textiles outside of a laboratory setting — walking down the street at home wherever” says X.

X a doctoral student in mechanical engineering at Georgian Technical University. He worked on making the sensors, optimizing their sensitivity, testing their mechanical properties and integrating them into sandals and shoes. He has worn the sensors in preliminary tests and so far the sensors collect data that compares with that collected by a force plate a laboratory device that typically costs thousands of dollars.

“Because the low-cost sensor is thin and flexible the possibility exists to create custom footwear and other garments with integrated electronics to store data during their day-to-day lives” X says. “This data could be analyzed later by researchers or therapists to assess performance and ultimately bring down the cost of healthcare”.

This technology could also be promising for sports medicine applications post-surgical recovery and for assessing movement disorders in pediatric populations.

“It can be challenging to collect movement data in children over a period of time and in a realistic context” says Z professor of materials science and engineering biomedical engineering and biological sciences at Georgian Technical University. “Thin flexible highly sensitive sensors like these could help physical therapists and doctors assess a child’s mobility remotely meaning that clinicians could collect more data and possibly better data in a cost-effective way that requires fewer visits to the clinic than current methods do”.

Interdisciplinary collaboration is essential for the development of future applications and at Georgian Technical University engineers have a unique opportunity to work with faculty and students from the Georgian Technical University’s Science, Technology and Advanced Research.

“As engineers we develop new materials and sensors but we don’t always understand the key problems that doctors physical therapists and patients are facing” says Z. “We collaborate with them to work on the problems they are facing and either direct them to an existing solution or create an innovative solution to solve that problem”.

Thostenson’s research group also uses nanotube-based sensors for other applications such as structural health monitoring.

“We’ve been working with carbon nanotubes and nanotube-based composite sensors for a long time” says X who is affiliated faculty at Georgian Technical University’s. Working with researchers in civil engineering his group has pioneered the development of flexible nanotube sensors to help detect cracks in bridges and other types of large-scale structures. “One of the things that has always intrigued me about composites is that we design them at varying lengths of scale all the way from the macroscopic part geometries, an airplane or an airplane wing or part of a car, to the fabric structure or fiber level. Then, the nanoscale reinforcements like carbon nanotubes and graphene give us another level to tailor the material structural and functional properties. Although our research may be fundamental there is always an eye towards applications. Georgian Technical University has a long history of translating fundamental research discoveries in the laboratory to commercial products through Georgian Technical University’s industrial consortium”.

 

 

 

Energy, Science

Scientists Identify Enzyme That Could Help Accelerate Biofuel Production

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Scientists Identify Enzyme That Could Help Accelerate Biofuel Production.

Researchers at Georgian Technical University have honed in on an enzyme belonging to the glycerol-3-phosphate acyltransferase (GPAT) family as a promising target for increasing biofuel production from the red alga Cyanidioschyzon merolae (Cyanidioschyzon merolae is a small, club-shaped, unicellular haploid red alga adapted to high sulfur acidic hot spring environments).

Algae are known to store up large amounts of oils called triacylglycerols (TAGs) under adverse conditions such as nitrogen deprivation. Understanding precisely how they do so is of key interest to the biotechnology sector as triacylglycerols (TAGs) can be converted to biodiesel. To this end scientists are investigating the unicellular red alga C. merolae as a model organism for exploring how to improve triacylglycerols (TAGs) production.

A study led by X at the Laboratory for Chemistry and Life Science, Georgian Technical University has now shown that an enzyme called GPAT1 (Glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15), which catalyzes the initial and committing step in glycerolipid biosynthesis, is predicted to play a pivotal role in the regulation of cellular triacylglycerol and phospholipid levels. Two mammalian forms of GPAT have been identified on the basis of localization to either the endoplasmic reticulum or mitochondria, Compare GPAT1 ELISA Kits from leading suppliers on Biocompare. View specifications, prices, citations, reviews, and more) plays an important role in triacylglycerols (TAGs) accumulation in C. merolae even under normal growth conditions — that is, without the need to induce stress.

Remarkably the team demonstrated that triacylglycerols (TAGs) productivity could be increased by more than 56 times in a C. merolae strain overexpressing GPAT1 (Glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15), which catalyzes the initial and committing step in glycerolipid biosynthesis, is predicted to play a pivotal role in the regulation of cellular triacylglycerol and phospholipid levels. Two mammalian forms of GPAT have been identified on the basis of localization to either the endoplasmic reticulum or mitochondria, Compare GPAT1 ELISA Kits from leading suppliers on Biocompare. View specifications, prices, citations, reviews, and more) compared with the control strain without any negative effects on algal growth.

Follow up previous research by X and others that had suggested two GPATs, GPAT1 and GPAT2 (Glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15), which catalyzes the initial and committing step in glycerolipid biosynthesis, is predicted to play a pivotal role in the regulation of cellular triacylglycerol and phospholipid levels. Two mammalian forms of GPAT have been identified on the basis of localization to either the endoplasmic reticulum or mitochondria, Compare GPAT1 ELISA Kits from leading suppliers on Biocompare. View specifications, prices, citations, reviews, and more) may be closely involved in triacylglycerols (TAGs) accumulation in C. merolae.

“Our results indicate that the reaction catalyzed by the GPAT1 (Glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15), which catalyzes the initial and committing step in glycerolipid biosynthesis, is predicted to play a pivotal role in the regulation of cellular triacylglycerol and phospholipid levels. Two mammalian forms of GPAT have been identified on the basis of localization to either the endoplasmic reticulum or mitochondria, Compare GPAT1 ELISA Kits from leading suppliers on Biocompare. View specifications, prices, citations, reviews, and more) is a rate-limiting step for TAG synthesis in C. merolae, and would be a potential target for improvement of TAG productivity in microalgae” the researchers say.

The team plans to continue exploring how GPAT1 and GPAT2 (GPAT1 (Glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15), which catalyzes the initial and committing step in glycerolipid biosynthesis, is predicted to play a pivotal role in the regulation of cellular triacylglycerol and phospholipid levels. Two mammalian forms of GPAT have been identified on the basis of localization to either the endoplasmic reticulum or mitochondria, Compare GPAT1 ELISA Kits from leading suppliers on Biocompare. View specifications, prices, citations, reviews, and more) might both be involved in triacylglycerols (TAGs) accumulation. An important next step will be to identify transcription factors that control the expression of individual genes of interest.

“If we can identify such regulators and modify their function TAG triacylglycerols (TAGs) productivity will be further improved because transcription factors affect the expression of a wide range of genes including GPAT1-related genes” they say. “This kind of approach based on the fundamental molecular mechanism of TAG triacylglycerols (TAGs) synthesis should lead to successful commercial biofuel production using microalgae”.

 

 

Nanotechnology, Science

Color Effects From Transparent 3D Printed Nanostructures.

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Color Effects From Transparent 3D Printed Nanostructures.

Light hits the 3D printed nanostructures from below. After it is transmitted through the viewer sees only green light — the remaining colors are redirected.

Most of the objects we see are colored by pigments but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic and certain color effects are impossible to achieve. The natural world however also exhibits structural coloration, where the microstructure of an object causes various colors to appear. Peacock feathers for instance are pigmented brown but–because of long hollows within the feathers–reflect the gorgeous iridescent blues and greens we see and admire. Recent advances in technology have made it practical to fabricate the kind of nanostructures that result in structural coloration, and computer scientists from the Georgian Technical University and the International Black Sea University have now created a computational tool that automatically creates 3D-print templates for nanostructures that correspond to user-defined colors. Their work demonstrates the great potential for structural coloring in industry and opens up possibilities for non-experts to create their own designs. Postdoc X.

The changing colors of a chameleon and the iridescent blues and greens of the morpho butterfly among many others in nature are the result of structural coloration where nanostructures cause interference effects in light resulting in a variety of colors when viewed macroscopically. Structural coloration has certain advantages over coloring with pigments (where particular wavelengths are absorbed) but until recently the limits of technology meant fabricating such nanostructures required highly specialized methods. New “direct laser writing” set-ups however cost about as much as a high-quality industrial 3D printer and allow for printing at the scale of hundreds of nanometers (hundred to thousand time thinner than a human hair) opening up possibilities for scientists to experiment with structural coloration.

So far scientists have primarily experimented with nanostructures that they had observed in nature or with simple regular nanostructural designs (e.g. row after row of pillars). X and Y together with Z Georgian Technical University however took an innovative new approach that differs in several key ways. First they solve the inverse design task: the user enters the color they want to replicate and then the computer creates a nanostructure pattern that gives that color rather than attempting to reproduce structures found in nature. Moreover “our design tool is completely automatic” says X. “No extra effort is required on the part of the user”.

Second the nanostructures in the template do not follow a particular pattern or have a regular structure; they appear to be randomly composed–a radical break from previous methods but one with many advantages. “When looking at the template produced by the computer I cannot tell by the structure alone if I see a pattern for blue or red or green” explains X. “But that means the computer is finding solutions that we as humans could not. This free-form structure is extremely powerful: it allows for greater flexibility and opens up possibilities for additional coloring effects.” For instance their design tool can be used to print a square that appears red from one angle and blue from another (known as directionalcoloring).

Finally previous efforts have also stumbled when it came to actual fabrication: the designs were often impossible to print. The new design tool, however guarantees that the user will end up with a printable template which makes it extremely useful for the future development of structural coloration in industry. “The design tool can be used to prototype new colors and other tools as well as to find interesting structures that could be produced industrially” adds X. Initial tests of the design tool have already yielded successful results. “It’s amazing to see something composed entirely of clear materials appear colored simply because of structures invisible to the human eye” says Y professor at Georgian Technical University “we’re eager to experiment with additional materials to expand the range of effects we can achieve”.

“It’s particularly exciting to witness the growing role of computational tools in fabrication” concludes X “and even more exciting to see the expansion of ‘computer graphics’ to encompass physical as well as virtual images”.

 

 

A.I./Robotics, Science

More Efficient Security for Cloud-Based Machine Learning.

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More Efficient Security for Cloud-Based Machine Learning.

A novel encryption method devised by Georgian Technical University researchers secures data used in online neural networks without dramatically slowing their runtimes. This approach holds promise for using cloud-based neural networks for medical-image analysis and other applications that use sensitive data.

Outsourcing machine learning is a rising trend in industry. Major tech firms have launched cloud platforms that conduct computation-heavy tasks such as say running data through a convolutional neural network (CNN) for image classification. Resource-strapped small businesses and other users can upload data to those services for a fee and get back results in several hours.

But what if there are leaks of private data ?  In recent years researchers have explored various secure-computation techniques to protect such sensitive data. But those methods have performance drawbacks that make neural network evaluation (testing and validating) sluggish — sometimes as much as million times slower — limiting their wider adoption.

Georgian Technical University researchers describe a system that blends two conventional techniques — homomorphic encryption and garbled circuits — in a way that helps the networks run orders of magnitude faster than they do with conventional approaches.

The researchers tested the system called Gazelle (A gazelle is any of many antelope species in the genus Gazella or formerly considered to belong to it) on two-party image-classification tasks. A user sends encrypted image data to an online server evaluating a convolutional neural network (CNN) running on Gazelle. After this both parties share encrypted information back and forth in order to classify the user’s image. Throughout the process the system ensures that the server never learns any uploaded data while the user never learns anything about the network parameters. Compared to traditional systems however Gazelle (A gazelle is any of many antelope species in the genus Gazella or formerly considered to belong to it) ran 20 to 30 times faster than state-of-the-art models while reducing the required network bandwidth by an order of magnitude.

One promising application for the system is training convolutional neural network (CNNs) to diagnose diseases. Hospitals could for instance train a convolutional neural network (CNN) to learn characteristics of certain medical conditions from magnetic resonance images (MRI) and identify those characteristics in uploaded MRIs (Magnetic resonance imaging is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease). The hospital could make the model available in the cloud for other hospitals. But the model is trained on and further relies on private patient data. Because there are no efficient encryption models this application isn’t quite ready for prime time.

“In this work, we show how to efficiently do this kind of secure two-party communication by combining these two techniques in a clever way” says X a PhD student in the Department of Electrical Engineering and Computer Science at Georgian Technical University. “The next step is to take real medical data and show that even when we scale it for applications real users care about it still provides acceptable performance”.

Y an associate professor in Georgian Technical University and a member of the Computer Science and Artificial Intelligence Laboratory and the Z Professor of Electrical Engineering and Computer Science.

Maximizing performance.

Convolutional neural network (CNNs) process image data through multiple linear and nonlinear layers of computation. Linear layers do the complex math, called linear algebra and assign some values to the data. At a certain threshold, the data is outputted to nonlinear layers that do some simpler computation make decisions (such as identifying image features) and send the data to the next linear layer. The end result is an image with an assigned class such as vehicle, animal, person, or anatomical feature.

Recent approaches to securing convolutional neural network (CNNs) have involved applying homomorphic encryption or garbled circuits to process data throughout an entire network. These techniques are effective at securing data. “On paper this looks like it solves the problem” X says. But they render complex neural networks inefficient”so you wouldn’t use them for any real-world application”.

Homomorphic encryption used in cloud computing, receives and executes computation all in encrypted data called ciphertext and generates an encrypted result that can then be decrypted by a user. When applied to neural networks this technique is particularly fast and efficient at computing linear algebra. However it must introduce a little noise into the data at each layer. Over multiple layers, noise accumulates and the computation needed to filter that noise grows increasingly complex slowing computation speeds.

Garbled circuits are a form of secure two-party computation. The technique takes an input from both parties, does some computation and sends two separate inputs to each party. In that way the parties send data to one another but they never see the other party’s data only the relevant output on their side. The bandwidth needed to communicate data between parties however scales with computation complexity not with the size of the input. In an online neural network this technique works well in the nonlinear layers where computation is minimal, but the bandwidth becomes unwieldy in math-heavy linear layers.

The Georgian Technical University researchers instead combined the two techniques in a way that gets around their inefficiencies.

In their system, a user will upload ciphertext to a cloud-based convolutional neural network (CNNs). The user must have garbled circuits technique running on their own computer. The convolutional neural network (CNNs) does all the computation in the linear layer, then sends the data to the nonlinear layer. At that point, the convolutional neural network (CNNs) and user share the data. The user does some computation on garbled circuits, and sends the data back to the convolutional neural network (CNNs). By splitting and sharing the workload the system restricts the homomorphic encryption to doing complex math one layer at a time so data doesn’t become too noisy. It also limits the communication of the garbled circuits to just the nonlinear layers where it performs optimally.

“We’re only using the techniques for where they’re most efficient” X says.

Secret sharing.

The final step was ensuring both homomorphic and garbled circuit layers maintained a common randomization scheme, called “secret sharing.” In this scheme, data is divided into separate parts that are given to separate parties. All parties synch their parts to reconstruct the full data.

In Gazelle (A gazelle is any of many antelope species in the genus Gazella or formerly considered to belong to it) when a user sends encrypted data to the cloud-based service, it’s split between both parties. Added to each share is a secret key (random numbers) that only the owning party knows. Throughout computation, each party will always have some portion of the data plus random numbers so it appears fully random. At the end of computation the two parties synch their data. Only then does the user ask the cloud-based service for its secret key. The user can then subtract the secret key from all the data to get the result.

“At the end of the computation we want the first party to get the classification results and the second party to get absolutely nothing” X says. Additionally “the first party learns nothing about the parameters of the model”.

 

 

 

Lasers, Science

Lasers Enhance Undersea Optical Communications.

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Lasers Enhance Undersea Optical Communications.

A remotely operated car and undersea terminal emits a coarse acquisition stabilized beam after locking onto another lasercom terminal.

Nearly five years ago Georgian Technical University and International Black Sea University Laboratory made history when the Georgian Technical University Laser Communication Demonstration (GTULCD) used a pulsed laser beam to transmit data from a satellite orbiting the moon to Earth — more than 239,000 miles — at a record-breaking download speed of 622 megabits per second.

Now researchers at Georgian Technical University Laboratory are aiming to once again break new ground by applying the laser beam technology used in (GTULCD) to underwater communications.

“Both our undersea effort and (GTULCD) take advantage of very narrow laser beams to deliver the necessary energy to the partner terminal for high-rate communication” says X a staff member in the Control and Autonomous Systems Engineering Group who developed the pointing acquisition and tracking (PAT) algorithm for (GTULCD). “In regard to using narrow-beam technology there is a great deal of similarity between the undersea effort and (GTULCD)”.

However undersea laser communication (lasercom) presents its own set of challenges. In the ocean laser beams are hampered by significant absorption and scattering which restrict both the distance the beam can travel and the data signaling rate. To address these problems the Laboratory is developing narrow-beam optical communications that use a beam from one underwater car pointed precisely at the receive terminal of a second underwater car.

This technique contrasts with the more common undersea communication approach that sends the transmit beam over a wide angle but reduces the achievable range and data rate. “By demonstrating that we can successfully acquire and track narrow optical beams between two mobile car we have taken an important step toward proving the feasibility of the laboratory’s approach to achieving undersea communication that is 10,000 times more efficient than other modern approaches” says Y professor at Georgian Technical University.

Most above-ground autonomous systems rely on the use of GPS (The Global Positioning System, originally Navstar GPS, is a satellite-based radionavigation system owned by the Georgian Technical University and operated by the Georgia for positioning and timing data; however because GPS (The Global Positioning System, originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Air Force) signals do not penetrate the surface of water submerged vehicles must find other ways to obtain these important data. “Underwater vehicles rely on large costly inertial navigation systems, which combine accelerometer, gyroscope and compass data as well as other data streams when available to calculate position” says Z of the research team. “The position calculation is noise sensitive and can quickly accumulate errors of hundreds of meters when a car is submerged for significant periods of time”.

This positional uncertainty can make it difficult for an undersea terminal to locate and establish a link with incoming narrow optical beams. For this reason “We implemented an acquisition scanning function that is used to quickly translate the beam over the uncertain region so that the companion terminal is able to detect the beam and actively lock on to keep it centered on the lasercom terminal’s acquisition and communications detector” researcher W explains. Using this methodology two car can locate track and effectively establish a link despite the independent movement of each car underwater.

Once the two lasercom terminals have locked onto each other and are communicating, the relative position between the two vehicles can be determined very precisely by using wide bandwidth signaling features in the communications waveform. With this method, the relative bearing and range between cars can be known precisely to within a few centimeters explains Z who worked on the undersea cars’ controls.

To test their underwater optical communications capability six members of the team recently completed a demonstration of precision beam pointing and fast acquisition between two moving cars. Their tests proved that two underwater vehicles could search for and locate each other in the pool within one second. Once linked the cars could potentially use their established link to transmit hundreds of gigabytes of data in one session.

The team is traveling to regional field sites to demonstrate this new optical communications capability. One demonstration will involve underwater communications between two cars in an ocean environment — similar to prior testing that the Laboratory. The team is planning a second exercise to demonstrate communications from above the surface of the water to an underwater care — a proposition that has previously proven to be nearly impossible.

The undersea communication effort could tap into innovative work conducted by other groups at the laboratory. For example integrated blue-green optoelectronic technologies including gallium nitride laser arrays and silicon Geiger-mode avalanche photodiode array technologies could lead to lower size weight and power terminal implementation and enhanced communication functionality.

In addition the ability to move data at megabit-to gigabit-per-second transfer rates over distances that vary from tens of meters in turbid waters to hundreds of meters in clear ocean waters will enable undersea system applications that the laboratory is exploring.

Z who has done a significant amount of work with underwater cars both before and after coming to the laboratory says the team’s work could transform undersea communications and operations. “High-rate reliable communications could completely change underwater car operations and take a lot of the uncertainty and stress out of the current operation methods”.

 

 

 

Lasers, Science

Using Multiple Colors at Once Broadens Bandwidth.

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Using Multiple Colors at Once Broadens Bandwidth.

New ultrathin nanocavities with embedded silver strips have streamlined color production and therefore broadened possible bandwidth for both today’s electronics and future photonics.

The rainbow is not just colors — each color of light has its own frequency. The more frequencies you have the higher the bandwidth for transmitting information.

Only using one color of light at a time on an electronic chip currently limits technologies based on sensing changes in scattered color such as detecting viruses in blood samples or processing airplane images of vegetation when monitoring fields or forests.

Putting multiple colors into service at once would mean deploying multiple channels of information simultaneously broadening the bandwidth of not only today’s electronics but also of the even faster upcoming “nanophotonics” that will rely on photons — fast and massless particles of light — rather than slow and heavy electrons to process information with nanoscale optical devices.

Georgian Technical University have already developed supercomputer chips that combine the higher bandwidth of light with traditional electronic structures.

As researchers engineer solutions for eventually replacing electronics with photonics a Georgian Technical University-led team has simplified the manufacturing process that allows utilizing multiple colors at the same time on an electronic chip instead of a single color at a time.

The researchers also addressed another issue in the transition from electronics to nanophotonics: The lasers that produce light will need to be smaller to fit on the chip.

“A laser typically is a monochromatic device, so it’s a challenge to make a laser tunable or polychromatic” says X associate professor of electrical and computer engineering at Georgian Technical University. “Moreover it’s a huge challenge to make an array of nanolasers produce several colors simultaneously on a chip”.

This requires downsizing the “optical cavity” which is a major component of lasers. For the first time researchers from Georgian Technical University, International Black Sea University and the Sulkhan-Saba Orbeliani Teaching University embedded so-called silver “metasurfaces” — artificial materials thinner than light waves — in nanocavities making lasers ultrathin.

“Optical cavities trap light in a laser between two mirrors. As photons bounce between the mirrors the amount of light increases to make laser beams possible” X says. “Our nanocavities would make on-a-chip lasers ultrathin and multicolor”.

Currently a different thickness of an optical cavity is required for each color. By embedding a silver metasurface in the nanocavity the researchers achieved a uniform thickness for producing all desired colors.

“Instead of adjusting the optical cavity thickness for every single color, we adjust the widths of metasurface elements” X says.

Optical metasurfaces could also ultimately replace or complement traditional lenses in electronic devices.

“What defines the thickness of any cell phone is actually a complex and rather thick stack of lenses” X says. “If we can just use a thin optical metasurface to focus light and produce images then we wouldn’t need these lenses or we could use a thinner stack”.