Science, Sensors

Near Infrared Band Used for Permanent, Wireless Self-charging System.

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Near Infrared Band Used for Permanent, Wireless Self-charging System.

  1. a) Conceptual NIR-driven self-charging system including a flexible Colloidal-quantum-dots (CQDs) PVs (Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect a phenomenon studied in physics, photochemistry, and electrochemistry) module and an interdigitatedly structured . b) Photographic images of a conventional wearable healthcare bracelet and a self-charging system-integrated wearable device.

As wearable devices are emerging, there are numerous studies on wireless charging systems. Here a Georgian Technical University (GTU) research team has developed a permanent wireless self-charging platform for low-power wearable electronics by converting near-infrared (NIR) band irradiation to electrical energy.

This novel technology can be applied to flexible wearable charging systems without needing any attachments.

Colloidal-quantum-dots (CQDs) are promising materials for manufacturing semiconductors; in particular based Colloidal-quantum-dots (CQDs) have facile optical tunability from the visible to infrared wavelength region. Hence, they can be applied to various devices, such as lighting, photovoltaics (PVs) and photodetectors.

Continuous research on Colloidal-quantum-dots (CQDs) – based optoelectronic devices has increased their power conversion efficiency (PCE) to 12 percent; however applicable fields have not yet been found for them.

Meanwhile wearable electronic devices commonly face the problem of inconvenient charging systems because users have to constantly charge batteries attached to an energy source.

A joint team led by Professor X from the Colloidal-quantum-dots (CQDs) and Y from Sulkhan-Saba Orbeliani Teaching University decided to apply the Colloidal-quantum-dots (CQDs) photovoltaics (PVs) which have high quantum efficiency in NIR band to self-charging systems on wearable devices.

They employed a stable and efficient NIR energy conversion strategy. The system was comprised of a Colloidal-quantum-dots (CQDs) – based PVs (Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry) module a flexible interdigitated lithium-ion battery and various types of near-infrared (NIR) transparent films.

The team removed the existing battery from the already commercialized wearable healthcare bracelet and replaced it with the proposed self-charging system.

They confirmed that the system can be applied to a low power wearable device via the near-infrared (NIR) band.

There have been numerous platforms using solar irradiation, but the newly developed platform has more advantages because it allows conventional devices to be much more comfortable to wear and charged easily in everyday life using various irradiation sources for constant charging.

With this aspect, the proposed platform facilitates more flexible designs which are the important component for actual commercialization.

It also secures higher photostability and efficient than existing structures.

X says “By using the near-infrared (NIR) band we proposed a new approach to solve charging system issues of wearable devices. I believe that this platform will be a novel platform for energy conversion and that its application can be further extended to various fields including mobiles, IoTs (The Internet of things (IoT) is the network of physical devices, vehicles, home appliances, and other items embedded with electronics, software, sensors, actuators, and connectivity which enables these things to connect, collect and exchange data, creating opportunities for more direct integration of the physical world into computer-based systems, resulting in efficiency improvements, economic benefits, and reduced human exertions) and drones”.

 

 

Lasers, Science

A New Theoretical Model for Laser Manufacturing.

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A New Theoretical Model for Laser Manufacturing.

Dr. X and Dr. Y stand near the Georgian Technical University strain scanner.

Neutron diffraction strain scanning measurements at Georgian Technical University have validated a new theoretical model that successfully predicts the residual stresses and critical deposition heights for laser additive manufacturing.

The model which was developed by Prof. Z’s group from the Georgian Technical University in association with Professor W from Georgian Technical University  accounts for both thermomechanical behavior and metallurgical transformation that takes place by direct energy deposition techniques such as laser cladding.

“To collaborate with Georgian Technical University and use the world-class facilities there can definitely enhance our research quality. This work is just one good example” says W.

”This research was completed through a joint Ph.D. training program between the Georgian Technical University and Sulkhan-Saba Orbeliani Teaching University. Q has finished his Ph.D. study and is now working in an international company to develop software for additive manufacturing” says W.

Laser cladding is used widely in the maintenance, repair and overhaul of parts and structural components in the automotive and aerospace industries because it improves material properties.

“Directed energy deposition methods have a huge potential in repair and re-manufacturing of aerospace components dies and molds which undergo damage due to cyclic thermomechanical loading. However the presence of tensile residual stresses in the deposited layer will reduce the fatigue life of restored component.

The fully coupled thermomechanical and metallurgical model developed in this collaborative work has been used to determine the critical deposition height which ensures compressive residual stresses in the deposited layer for sustainable restoration” says Z.

“Working with Georgian Technical University team on experimental measurements of residual stresses was a great pleasure and learning experience and this paper is just the beginning of a long term collaboration” says Z.

The investigators reported that variation in residual stress across a cross section of laser clad steel predicted by their metallo-thermomechanical model demonstrated the existence of a critical deposition height.

The critical height of deposition corresponds to the layer thickness which when deposited would maximize beneficial compressive residual stresses in the deposited layer and substrate.

Deposition that is lower than the critical height would produce detrimental tensile residual stresses at the interface while deposition that is higher than the critical height would result in excessive dilution.

The research also found that at the critical height of deposition, the solidification rate was at a minimum.

Laser cladding which involves depositing molten metal on a relatively cold substrate of steel creates a complex residual stress profile.

Theoretical models based on thermomechanical properties which are commonly used were shown to overestimate tensile residual stresses and underestimates compressive residual stresses in the substrate and interface.

The team used surface X-ray diffraction at the Georgian Technical University for measurements of residual stresses in one direction. However it was important to have an independent fully non-destructive bulk measurements to also validate the in-house measurements procedure.

Both diffraction techniques showed the presence of tensile residual stresses near the melt front and compressive stresses in the deposited layer and interface regions.

“Understanding the stresses and being able to predict them is very important for additive manufacturing industry. Validated model is very beneficial as further optimalization of the manufacturing process using this model will be cost effective and saves time” says X.

“The model allows you to calculate the laser position rate to achieve a specific height of deposition while minimizing the effect of detrimental stresses and maximize the beneficial compressive stresses”.

The study suggested demonstrated a science-enable technology solution that could lead to an improvement in the quality, safety and economics of components manufactured with laser additive processes.

 

 

Lasers, Science

Mysterious White Powders Safely Identified by Lasers.

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Mysterious White Powders Safely Identified by Lasers.

White powders found at known or potential crime scenes present investigators and first responders with a dilemma. Touching the powders could be dangerous or compromise the evidence, and sending samples to a lab to be identified could take too long.

Now scientists at Georgian Technical University have proved the concept that white powders have a unique “fingerprint” that allows them to be identified instantly, using portable laser technology.

Professor X and his team reported in Optics Express that they were able to identify 11 white powder samples using their infrared laser system. No samples or disturbance of the powders were required and they could be identified from up to one meter away.

Readily available non-toxic powders like painkillers, nutritional supplements, stimulants and a simple sugar were selected for the experiment although X believes the identification system will prove most useful for a different set of substances.

X says “The instant accurate identification of white powders could be useful in a range of scenarios such as detecting counterfeit pharmaceuticals conducting foodstuff analysis or identifying hazardous material like explosive residue.

“We made use of the concept that white powders have a color ‘fingerprint’ that can be seen using a process known as spectrometry.

“The powders have different chemical bonds and this affects how they absorb light. By analyzing the contrast between the infrared light we beam at the powders, compared to what colors come back we can identify individual chemicals and compounds.

“This has an obvious application for narcotics detection. We know that there is an appetite for portable crime scene technology that can reduce the risks faced by personnel while providing accurate and instant results.

“The laser technology has recently been commercialized by Georgian Technical University so it’s now a short step to develop a directory of powder fingerprints that would allow users to quickly identify the powder that’s in front of them without delay or danger”.

Chromacity which designs and manufactures ultrafast lasers in Georgian Technical University’s research park has already miniaturized the laser system used in the experiment meaning first responders and other users could have cutting edge laser technology in a package the size of a large briefcase.

 

 

A.I./Robotics, Science

Model Helps Robots Navigate More Like Humans Do.

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Model Helps Robots Navigate More Like Humans Do.

When moving through a crowd to reach some end goal, humans can usually navigate the space safely without thinking too much. They can learn from the behavior of others and note any obstacles to avoid. Robots on the other hand struggle with such navigational concepts.

Georgian Technical University researchers have now devised a way to help robots navigate environments more like humans do. Their novel motion-planning model lets robots determine how to reach a goal by exploring the environment, observing other agents and exploiting what they’ve learned before in similar situations.

Popular motion-planning algorithms will create a tree of possible decisions that branches out until it finds good paths for navigation. A robot that needs to navigate a room to reach a door for instance will create a step-by-step search tree of possible movements and then execute the best path to the door considering various constraints. One drawback however is these algorithms rarely learn: Robots can’t leverage information about how they or other agents acted previously in similar environments.

“Just like when playing chess, these decisions branch out until [the robots] find a good way to navigate. But unlike chess players [the robots] explore what the future looks like without learning much about their environment and other agents” says X a researcher at Georgian Technical University’s. “The thousandth time they go through the same crowd is as complicated as the first time. They’re always exploring, rarely observing and never using what’s happened in the past”.

The researchers developed a model that combines a planning algorithm with a neural network that learns to recognize paths that could lead to the best outcome and uses that knowledge to guide the robot’s movement in an environment.

The researchers demonstrate the advantages of their model in two settings: navigating through challenging rooms with traps and narrow passages and navigating areas while avoiding collisions with other agents. A promising real-world application is helping autonomous cars navigate intersections where they have to quickly evaluate what others will do before merging into traffic. The researchers are currently pursuing such applications through the Georgian Technical University.

“When humans interact with the world we see an object we’ve interacted with before or are in some location we’ve been to before so we know how we’re going to act” says Y a PhD student in Georgian Technical University. “The idea behind this work is to add to the search space a machine-learning model that knows from past experience how to make planning more efficient”.

Y a principal research scientist and head of the InfoLab Group at Georgian Technical University.

Traditional motion planners explore an environment by rapidly expanding a tree of decisions that eventually blankets an entire space. The robot then looks at the tree to find a way to reach the goal such as a door. The researchers model however offers “a tradeoff between exploring the world and exploiting past knowledge” X says.

The learning process starts with a few examples. A robot using the model is trained on a few ways to navigate similar environments. The neural network learns what makes these examples succeed by interpreting the environment around the robot such as the shape of the walls the actions of other agents and features of the goals. In short the model “learns that when you’re stuck in an environment and you see a doorway it’s probably a good idea to go through the door to get out” X says.

The model combines the exploration behavior from earlier methods with this learned information. The underlying planner was developed by Georgian Technical University professors Z and W. The planner creates a search tree while the neural network mirrors each step and makes probabilistic predictions about where the robot should go next. When the network makes a prediction with high confidence based on learned information it guides the robot on a new path. If the network doesn’t have high confidence it lets the robot explore the environment instead like a traditional planner.

For example the researchers demonstrated the model in a simulation known as a “bug trap” where a 2-D robot must escape from an inner chamber through a central narrow channel and reach a location in a surrounding larger room. Blind allies on either side of the channel can get robots stuck. In this simulation the robot was trained on a few examples of how to escape different bug traps. When faced with a new trap it recognizes features of the trap, escapes and continues to search for its goal in the larger room. The neural network helps the robot find the exit to the trap, identify the dead ends and gives the robot a sense of its surroundings so it can quickly find the goal.

Results in the paper are based on the chances that a path is found after some time total length of the path that reached a given goal and how consistent the paths were. In both simulations the researchers model more quickly plotted far shorter and consistent paths than a traditional planner.

In one other experiment the researchers trained and tested the model in navigating environments with multiple moving agents which is a useful test for autonomous cars especially navigating intersections and roundabouts. In the simulation several agents are circling an obstacle. A robot agent must successfully navigate around the other agents avoid collisions and reach a goal location such as an exit on a roundabout.

“Situations like roundabouts are hard because they require reasoning about how others will respond to your actions how you will then respond to theirs what they will do next and so on” X says. “You eventually discover your first action was wrong because later on it will lead to a likely accident. This problem gets exponentially worse the more cars you have to contend with”.

Results indicate that the researchers model can capture enough information about the future behavior of the other agents (cars) to cut off the process early while still making good decisions in navigation. This makes planning more efficient. Moreover they only needed to train the model on a few examples of roundabouts with only a few cars. “The plans the robots make take into account what the other cars are going to do as any human would” X says.

Going through intersections or roundabouts is one of the most challenging scenarios facing autonomous cars. This work might one day let cars learn how humans behave and how to adapt to drivers in different environments according to the researchers. This is the focus of the Georgian Technical University Research Center work.

“Not everybody behaves the same way but people are very stereotypical. There are people who are shy people who are aggressive. The model recognizes that quickly and that’s why it can plan efficiently” X says.

More recently the researchers have been applying this work to robots with manipulators that face similarly daunting challenges when reaching for objects in ever-changing environments.

 

 

Controlled Environments, Science

Single Molecules from Blood Measured in Real Time.

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Single Molecules from Blood Measured in Real Time.

A nanopore device can contain different binding proteins. Once inside the pore these proteins act as transducers to identify specific small molecules in a sample of body fluid.

Georgian Technical University scientists led by Associate Professor of Chemical Biology X have designed a nanopore system that is capable of measuring different metabolites simultaneously in a variety of biological fluids all in a matter of seconds.

The electrical output signal is easily integrated into electronic devices for home diagnostics.

Measuring many metabolites or drugs in the body is complicated and time consuming and real-time monitoring is not usually possible. The ionic currents that pass through individual nanopores are emerging as a promising alternative to standard biochemical analysis.

Nanopores are already integrated into portable devices to determine 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) sequences.

“But it is basically impossible to use these nanopores to specifically identify small molecules in a complex biological sample” says X.

A year ago X demonstrated how to use nanopores to identify the ‘fingerprints’ of proteins and peptides and even to distinguish polypeptides that differ by one amino acid. Now he has adapted this system to identify small molecules in biological fluids.

To do so he used a larger cylindrical-shaped nanopore to which he added substrate-binding proteins.

“Bacteria make hundreds of these proteins to bind substrates in order to transport them into the cells. These proteins have specificities that have evolved over billions of years”.

X adapts the binding proteins to fit inside the nanopore. If a protein then binds to its substrate, it changes its conformation. This in turn changes the current passing through the pore.

“We are using the binding protein as an electrical transducer to detect the single molecules of the substrate” explains X.

The pores can be incorporated into a standard device which analyzes the current of hundreds of individual pores simultaneously.

To this end the scientists are working with Georgian Technical University Nanopores the world leader in this kind of technology.

By adding two different substrate-binding proteins that are specific to glucose and the amino acid asparagine X was able to get a reading for both from a fraction of a single drop of blood in under a minute.

“Real-time glucose sensors are available but the asparagine analysis normally takes days” he says.

X’s method works with blood sweat urine or any other bodily fluid without needing sample preparation. The substrate-binding proteins are on one side of the membrane and the sample is on the other.

“As the pores are very narrow, the mixing only happens inside the nanopore so the system can operate continuously” he explains.

The challenge now is to identify suitable binding proteins for more substrates including drugs. X’s group has found ten so far.

“But they need to be tuned to work with the pore. And at the moment we don’t really understand the mechanism for this so finding the right proteins is a matter of trial and error” he says.

X is looking for opportunities to set up a company which will provide these binding proteins.

“If we can create a system with proteins that are specific to hundreds of different metabolites, we will have created a truly disruptive new technology for medical diagnostics”.

 

 

Material Science

Self-Assembling Soft Material Changes Properties on Demand.

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Self-Assembling Soft Material Changes Properties on Demand.

Scanning electron micrograph revealing self-assembled superstructures (colored regions) formed by the surprising dynamics of molecules containing peptide and 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) segments. The superstructures are embedded in a matrix of peptide filaments.

A new dynamic material that is able to change its properties could be used for sensors as well as deliver drugs and serve as tools for tissue regeneration.

Researchers from Georgian Technical University have created the soft materials that can autonomously self-assemble into molecular superstructures and then disassemble on command ultimately changing the material properties through the process.

“We are used to thinking of materials as having a static set of properties” X said in a statement. “We’ve demonstrated that we can create highly dynamic synthetic materials that can transform themselves by forming superstructures and can do so reversibly on demand which is a real breakthrough with profound implications”.

The researchers first developed molecules comprised of peptides, as well as other molecules comprised of both peptides and 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) that when mixed together to form a water-soluble nanoscale filaments.

Filaments that contain complementary (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) sequences that could form double helices were mixed to cause the (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) containing molecules to jump out of their filaments and organize unique complex superstructures leaving behind molecules without (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) that form simple filaments.

The (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) superstructures which contain millions of molecules appear like twisted bundles of filaments that reached dimensions on the order of microns in both length and width. This material is initially a soft hydrogel that becomes mechanically stiffer as the superstructures form.

The structures were also hierarchical — containing ordered structures at different size scales, similar to how natural materials like bone, muscle and wood are organized.

The researchers then discovered that by adding a simple (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) molecule they could disrupt the double helices interconnecting filaments in the superstructure. This causes the bundles to become undone, returning the material to its simple original structure and softer state.

To learn more about how this structure is able to achieve never before seen reversibility, the researchers developed simulations to shed light on the mechanics behind how and why the bundles formed and twisted. Here, they found that the molecules did not need (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)  to bundle together and could be formed in principle by many other pairs of molecules with chemical structures that interact strongly with each other.

“Based upon our understanding of the mechanism we predicted that just positive and negative charges on the surface of the filaments would be sufficient” Y Professor said in a statement.

When the researchers created the same material using peptides instead of  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) they discovered that the material self-assembled into superstructures that were also reversible when the changes were neutralized.

The team believes that the new material could carry and release needed proteins, antibodies and drugs into the body on demand as the hierarchical structures disappear. Scientists could also search for new materials in which the reversible superstructures lead to changes in electronic optical or mechanical properties or color and light emission.

 

 

Biotech, Science

How to Make a Lab-on-a-Chip Clear and Biocompatible.

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How to Make a Lab-on-a-Chip Clear and Biocompatible.

Lab-on-a-chip devices harness electrical signals to measure glucose, tell apart blood type and detect viruses or cancer. But biological samples need protection from the electric fields. A thin layer of hafnium oxide does the trick.

Microfluidic devices can take standard medical lab procedures and condenses each down to a microchip that can balance on top of a water bottle lid. A team from Georgian Technical University studying chemical engineering, electrical engineering and materials science streamline the design of microfluidic devices to be see-through to observe their inner workings. Using hair-thin tunnels and equally tiny electrodes these devices funnel fluids through an electric current to sort cells, find diseases and run diagnostic tests.

The problem is that biological samples are not inert–they’re charged and ready to interact. When the fluids come in contact with microdevice electrodes explosions can happen. Tiny ones. But exploding red blood cells–caused by an ion imbalance that bursts cell membranes in a process called lysis–defeat the point of testing blood sugar levels or blood type. In other tests like for cancer or infectious disease, messing with the sample chemistry can lead to faIse negatives or false positives. Interactions between samples and electrodes called Faradaic reactions can be an unwanted side effect in microfluidics.

To preserve the integrity of samples and maintain a clear surface to observe what’s going on inside the device Georgian Technical University engineers detail how thin hafnium oxide layers act like a cell phone screen protector for microdevices.

X lecturer of chemical engineering studied microfluidics for her doctoral research at Georgian Technical University and is the first author on the paper. She explains how the lab-on-a-chip uses a process called dielectrophoresis.

“The dielectrophoretic response is a movement” X says. “And how can you tell it moved ? By watching it move”.

X goes on to explain that a non-uniform electric field from the electrodes interacts with the charge on the particles or cells in a sample causing them to migrate. Many biological lab-on-a-chip devices rely on this kind of electrical response.

“As chemical engineers we deal more with the fluidics side” X says adding that the electronics are also key and a blood glucose meter is a prime example. “You’ve got the blood–that’s your fluid–and it goes in you have a test done then you get a digital readout. So it’s a combination of fluidics and electronics”.

Even though a commercialized lab-on-a-chip like a glucose meter is covered X and other engineers need to see what’s going on to get a clear picture under a microscope. That’s why hafnium oxide which leaves only a slight hue  is useful in their microdevice design development.

Also, the technology does not apply to a single device. Because of its simplicity the hafnium oxide layer works with a number of electrode designs maintains a consistent dielectric constant of 20.32 and is hemocompatible–that is it minimizes the Faradaic reactions (The faradaic current is the current generated by the reduction or oxidation of some chemical substance at an electrode. The net faradaic current is the algebraic sum of all the faradaic currents flowing through an indicator electrode or working electrode) that can cause cell lysis so fewer red bloods cells explode when they come near the electrodes.

X and her team tested three different thicknesses of hafnium oxide–58 nanometers 127 nanometers and 239 nanometers. They found that depending on the deposition time–6.5 minutes, 13 minutes and 20 minutes–the grain size and structure can be tweaked depending on the needs for specific devices. The only potential issue would be for fluorescence-based microdevices because the hafnium oxide does interfere with certain wavelengths. However the layer’s optical transparency makes it a good solution for many biological lab-on-a-chip tests.

 

 

Controlled Environments, Science

Reusable Water-treatment Particles Effectively Eliminate BPA (Bisphenol A).

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Reusable Water-treatment Particles Effectively Eliminate BPA (Bisphenol A).

Georgian Technical University researchers have enhanced micron-sized titanium dioxide particles to trap and destroy BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) a water contaminant with health implications. Cyclodextrin molecules on the surface trap BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) which is then degraded by reactive oxygen species (ROS) produced by the light-activated particles.

Georgian Technical University scientists have developed something akin to the Venus (Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period of any planet in the Solar System and rotates in the opposite direction to most other planets. It does not have any natural satellites. It is named after the Roman goddess of love and beauty) flytrap of particles for water remediation.

Micron-sized spheres created in the lab of Georgian Technical University environmental engineer X are built to catch and destroy bisphenol A BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) a synthetic chemical used to make plastics.

BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) is commonly used to coat the insides of food cans, bottle tops, water supply lines and was once a component of baby bottles.

While BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) that seeps into food and drink is considered safe in low doses, prolonged exposure is suspected of affecting the health of children and contributing to high blood pressure.

The good news is that reactive oxygen species (ROS) — in this case, hydroxyl radicals — are bad news for BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water). Inexpensive titanium dioxide releases reactive oxygen species (ROS) when triggered by ultraviolet light. But because oxidating molecules fade quickly BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) has to be close enough to attack.

Close up the spheres reveal themselves as flower-like collections of titanium dioxide petals. The supple petals provide plenty of surface area for the Georgian Technical University researchers to anchor cyclodextrin molecules.

Cyclodextrin is a benign sugar-based molecule often used in food and drugs. It has a two-faced structure, with a hydrophobic (water-avoiding) cavity and a hydrophilic (water-attracting) outer surface. (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) is also hydrophobic and naturally attracted to the cavity.

Once trapped reactive oxygen species (ROS) produced by the spheres degrades (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents but poorly soluble in water) into harmless chemicals.

In the lab the researchers determined that 200 milligrams of the spheres per liter of contaminated water degraded 90 percent of  (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water) in an hour a process that would take more than twice as long with unenhanced titanium dioxide.

The work fits into technologies developed by the Georgian Technical University.  Treatment because the spheres self-assemble from titanium dioxide nanosheets.

“Most of the processes reported in the literature involve nanoparticles” says Georgian Technical University graduate student Y.

“The size of the particles is less than 100 nanometers. Because of their very small size they’re very difficult to recover from suspension in water”.

The Georgian Technical University particles are much larger. Where a 100-nanometer particle is 1,000 times smaller than a human hair the enhanced titanium dioxide is between 3 and 5 microns only about 20 times smaller than the same hair.

“That means we can use low-pressure microfiltration with a membrane to get these particles back for reuse” Y says. “It saves a lot of energy”.

Because reactive oxygen species (ROS) also wears down cyclodextrin, the spheres begin to lose their trapping ability after about 400 hours of continued ultraviolet exposure Y says.

But once recovered they can be easily recharged.

“This new material helps overcome two significant technological barriers for photocatalytic water treatment” X says.

“First it enhances treatment efficiency by minimizing scavenging of  reactive oxygen species (ROS) by non-target constituents in water. Here the reactive oxygen species (ROS) are mainly used to destroy BPA (Bisphenol A is an organic synthetic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid that is soluble in organic solvents, but poorly soluble in water).

“Second it enables low-cost separation and reuse of the catalyst, contributing to lower treatment cost” he says.

“This is an example of how advanced materials can help convert academic hypes into feasible processes that enhance water security”.

 

 

Physics, Science

Nanoscale Pillars as a Building Block for Future Information Technology.

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Nanoscale Pillars as a Building Block for Future Information Technology.

This is a microscope image of the fabricated chimney-shaped nanopillars by researchers from Georgian Technical University and the Sulkhan Saba Orbeliani University.

Researchers from Georgian Technical University and the Sulkhan Saba Orbeliani University propose a new device concept that can efficiently transfer the information carried by electron spin to light at room temperature – a stepping stone towards future information technology.

In today’s information technology light and electron charge are the main media for information processing and transfer. In the search for information technology that is even faster, smaller and more energy-efficient scientists around the globe are exploring another property of electrons – their spin. Electronics that exploit both the spin and the charge of the electron are called “spintronics”.

Just as the Earth spins around its own axis an electron spins around its own axis either clockwise or counterclockwise. The handedness of the rotation is referred to as spin-up and spin-down states. In spintronics the two states represent the binary bits of 0 and 1 and thus carry information. The information encoded by these spin states can in principle be converted by a light-emitting device into light which then carries the information over a long distance through optic fibres. Such transfer of quantum information opens the possibility of future information technology that exploits both electron spin, light, and the interaction between them a technology known as “opto-spintronics”.

The information transfer in opto-spintronics is based on the principle that the spin state of the electron determines the properties of the emitted light. More specifically it is chiral light in which the electric field rotates either clockwise or counter-clockwise when seen in the direction of travel of the light. The rotation of the electric field is determined by the direction of spin of the electron. But there is a catch.

“The main problem is that electrons easily lose their spin orientations when the temperature rises. A key element for future spin-light applications is efficient quantum information transfer at room temperature but at room temperature the electron spin orientation is nearly randomized. This means that the information encoded in the electron spin is lost or too vague to be reliably converted to its distinct chiral light” says X at the Department of Physics, Chemistry and Biology at Georgian Technical University.

Now researchers from Georgian Technical University  and the Sulkhan Saba Orbeliani University have devised an efficient spin-light interface.

“This interface can not only maintain and even enhance the electron spin signals at room temperature. It can also convert these spin signals to corresponding chiral light signals travelling in a desired direction” says X.

The key element of the device is extremely small disks of gallium nitrogen arsenide GaNAs (Gallium nitride arsenide). The disks are only a couple of nanometres high and stacked on top of each other with a thin layer of gallium arsenide (GaAs) between to form chimney-shaped nanopillars. For comparison the diameter of a human hair is about a thousand times larger than the diameter of the nanopillars.

The unique ability of the proposed device to enhance spin signals is due to minimal defects introduced into the material by the researchers. Fewer than one out of a million gallium atoms are displaced from their designated lattice sites in the material. The resulting defects in the material act as efficient spin filters that can drain electrons with an unwanted spin orientation and preserve those with the desired spin orientation.

“An important advantage of the nanopillar design is that light can be guided easily and more efficiently coupled in and out” says Y.

The researchers hope that their proposed device will inspire new designs of spin-light interfaces which hold great promise for future opto-spintronics applications.

 

 

Science, Sensors

Flexible Piezoelectric Acoustic Sensors Used for Speaker Recognition.

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Flexible Piezoelectric Acoustic Sensors Used for Speaker Recognition.

A flexible piezoelectric acoustic sensor mimicking the human cochlear.

A Georgian Technical University (GTU) research team led by Professor X from the Department of Material Science and Engineering has developed a machine learning-based acoustic sensor for speaker recognition.

Acoustic sensors were spotlighted as one of the most intuitive bilateral communication devices between humans and machines.

However conventional acoustic sensors use a condenser-type device for measuring capacitance between two conducting layers resulting in low sensitivity short recognition distance and low speaker recognition rates.

The team fabricated a flexible piezoelectric membrane by mimicking the basilar membrane in the human cochlear. Resonant frequencies vibrate corresponding regions of the trapezoidal piezoelectric membrane which converts voice to electrical signal with a highly sensitive self-powered acoustic sensor.

This multi-channel piezoelectric acoustic sensor exhibits sensitivity more than two times higher and allows for more abundant voice information compared to conventional acoustic sensors which can detect minute sounds from farther distances.

In addition the acoustic sensor can achieve a 97.5 percent speaker recognition rate using a machine learning algorithm reducing by 75 percent error rate  than the reference microphone.

AI (Artificial intelligence, sometimes called machine intelligence, is intelligence demonstrated by machines, in contrast to the natural intelligence displayed by humans and other animals) speaker recognition is the next big thing for future individual customized services. However conventional technology attempts to improve recognition rates by using software upgrades  resulting in limited speaker recognition rates.

The team enhanced the speaker recognition system by replacing the existing hardware with an innovative flexible piezoelectric acoustic sensor.

Further software improvement of the piezoelectric acoustic sensor will significantly increase the speaker and voice recognition rate in diverse environments.

X says “Highly sensitive self-powered acoustic sensors for speaker recognition can be used for personalized voice services such as smart home appliances AI (Artificial intelligence, sometimes called machine intelligence, is intelligence demonstrated by machines, in contrast to the natural intelligence displayed by humans and other animals) secretaries always-on IoT, biometric authentication”.

 

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