Using sunlight to convert plastic waste into useful chemicals

Asst Prof Soo Han Sen new photocatalyst

Chemists at Nanyang Technological University, Singapore (NTU Singapore) have discovered a method that could turn plastic waste into valuable chemicals by using sunlight.

In lab experiments, the research team mixed plastics with their catalyst in a solvent, which allows the solution to harness light energy and convert the dissolved plastics into formic acid – a chemical used in fuel cells to produce electricity.

Reporting their work in Advanced Science, the team led by NTU Assistant Professor Soo Han Sen from the School of Physical and Mathematical Sciences made their catalyst from the affordable, biocompatible metal vanadium, commonly used in steel alloys for vehicles and aluminum alloys for aircraft.

When the vanadium-based catalyst was dissolved in a solution containing a non-biodegradable consumer plastic like polyethylene and exposed to artificial sunlight, it broke down the carbon-carbon bonds within the plastic in six days.

This process turned the polyethylene into formic acid, a naturally occurring preservative and antibacterial agent, which can also be used for energy generation by power plants and in hydrogen fuel cell vehicles.

“We aimed to develop sustainable and cost-effective methods to harness sunlight to manufacture fuels and other chemical products,” said Asst Prof Soo. “This new chemical treatment is the first reported process that can completely break down a non-biodegradable plastic such as polyethylene using visible light and a catalyst that does not contain heavy metals.”

In Singapore, most plastic waste is incinerated, producing greenhouse gases such as carbon dioxide, and the leftover mass-burn ash – is transported to the Semakau landfill, which is estimated to run out of space by 2035.

Developing innovative zero-waste solutions, such as this environmentally friendly catalyst to turn waste into resources, is part of the NTU Smart Campus vision to develop a sustainable future.

Using energy from the sun to convert chemicals

The vanadium-based catalyst, which is supported by organic groups and typically abbreviated as LV(O), uses light energy to drive a chemical reaction and is known as a photocatalyst.

Photocatalysts enable chemical reactions to be powered by sunlight, unlike most reactions performed in the industry that require heat, usually generated through the burning of fossil fuels.

Other advantages of the new photocatalyst are that it is low cost, abundant, and environmentally friendly, unlike common catalysts made from expensive or toxic metals such as platinum, palladium or ruthenium.

While scientists have tried other approaches for turning waste plastics into useful chemicals, many approaches involve undesirable reagents or too many steps to scale up.

One example is an approach called photoreforming, where plastic is combined with water and sunlight to produce hydrogen gas, but this requires the use of catalysts containing cadmium, a toxic heavy metal. Other methods require plastics to be treated with harsh chemical solutions that are dangerous to handle.

Most plastics are non-biodegradable because they contain extraordinarily inert chemical bonds called carbon-carbon bonds, which are not readily broken down without the application of high temperatures.

The new vanadium-based photocatalyst developed by the NTU research team was specially designed to break these bonds, and does so by latching onto a nearby chemical group known as an alcohol group and using energy absorbed from sunlight to unravel the molecule like a zipper.

As the experiments were conducted at a laboratory scale, the plastic samples were first dissolved by heating to 85 degrees Celsius in a solvent, before the catalyst, which is in powder form, was dissolved. The solution was then exposed to artificial sunlight for a few days. Using this approach the team showed that their photocatalyst was able to break down the carbon-carbon bonds in over 30 different compounds and the results demonstrated the concept of an environmentally-friendly, low-cost photocatalyst.

The research team is now pursuing improvements to the process that may allow the breakdown of plastics to produce other useful chemical fuels, such as hydrogen gas.

Learn more: ?NTU Singapore scientists convert plastics into useful chemicals using sunlight

 

 

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Could microorganisms living in the gut alter or even slow down the ageing process?

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An international research team led by Nanyang Technological University, Singapore (NTU Singapore) has found that microorganisms living in the gut may alter the ageing process, which could lead to the development of food-based treatment to slow it down.

All living organisms, including human beings, coexist with a myriad of microbial species living in and on them, and research conducted over the last 20 years has established their important role in nutrition, physiology, metabolism and behaviour.

Using mice, the team led by Professor Sven Pettersson from the NTU Lee Kong Chian School of Medicine, transplanted gut microbes from old mice (24 months old) into young, germ-free mice (6 weeks old). After eight weeks, the young mice had increased intestinal growth and production of neurons in the brain, known as neurogenesis.

The team showed that the increased neurogenesis was due to an enrichment of gut microbes that produce a specific short chain fatty acid, called butyrate.

Butyrate is produced through microbial fermentation of dietary fibres in the lower intestinal tract and stimulates production of a pro-longevity hormone called FGF21, which plays an important role in regulating the body’s energy and metabolism. As we age, butyrate production is reduced.

The researchers then showed that giving butyrate on its own to the young germ-free mice had the same adult neurogenesis effects.

The study was published in Science Translational Medicine yesterday (13 November), and was undertaken by researchers from Singapore, UK, and Australia.

“We’ve found that microbes collected from an old mouse have the capacity to support neural growth in a younger mouse,” said Prof Pettersson. “This is a surprising and very interesting observation, especially since we can mimic the neuro-stimulatory effect by using butyrate alone.”

“These results will lead us to explore whether butyrate might support repair and rebuilding in situations like stroke, spinal damage and to attenuate accelerated ageing and cognitive decline”.

How gut microbes impact the digestive system

The team also explored the effects of gut microbe transplants from old to young mice on the functions of the digestive system.

With age, the viability of small intestinal cells is reduced, and this is associated with reduced mucus production that make intestinal cells more vulnerable to damage and cell death.

However, the addition of butyrate helps to better regulate the intestinal barrier function and reduce the risk of inflammation.

The team found that mice receiving microbes from the old donor gained increases in length and width of the intestinal villi – the wall of the small intestine. In addition, both the small intestine and colon were longer in the old mice than the young germ-free mice.

The discovery shows that gut microbes can compensate and support an ageing body through positive stimulation.

This points to a new potential method for tackling the negative effects of ageing by imitating the enrichment and activation of butyrate.

“We can conceive of future human studies where we would test the ability of food products with butyrate to support healthy ageing and adult neurogenesis,” said Prof Pettersson.

“In Singapore, with its strong food culture, exploring the use of food to ‘heal’ ourselves, would be an intriguing next step, and the results could be important in Singapore’s quest to support healthy ageing for their silver generation”.

Group leader Dr Dario Riccardo Valenzano at the Max Planck Institute for Biology of Ageing in Germany, who was not involved in the study, said the discovery is a milestone in research on microbiome.

“These results are exciting and raise several new open questions for both biology of aging and microbiome research, including whether there is an active acquisition of butyrate producing microbes during mice life and whether extreme aging leads to a loss of this fundamental microbial community, which may be eventually responsible for dysbiosis and age-related dysfunctions,” he added.

Professor Brian Kennedy, Director of the Centre for Healthy Ageing at the National University of Singapore, who provided an independent view, said, “It is intriguing that the microbiome of an aged animal can promote youthful phenotypes in a young recipient. This suggests that the microbiota with aging have been modified to compensate for the accumulating deficits of the host and leads to the question of whether the microbiome from a young animal would have greater or less effects on a young host. The findings move forward our understanding of the relationship between the microbiome and its host during ageing and set the stage for the development of microbiome-related interventions to promote healthy longevity.”

The study builds on Prof Pettersson’s earlier studies on how transplantation of gut microbes from healthy mice can restore muscle growth and function in germ-free mice with muscle atrophy, which is the loss of skeletal muscle mass.

Learn more: ?Bacteria in the gut may alter ageing process, finds NTU Singapore study

 

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A secure quantum communication chip 1,000 times smaller than current technology

Roughly about 3mm in size, the tiny chip developed by NTU scientists uses quantum communication algorithms to better security than existing industry standards. It also opens doors for more secure communication technologies that can be deployed in compact devices such as smartphones, tablets and wearables.

Researchers at Nanyang Technological University, Singapore (NTU Singapore) have developed a quantum communication chip that is 1,000 times smaller than current quantum setups, but offers the same superior security quantum technology is known for.

Most leading security standards used in secure communication methods – from withdrawing cash from the ATM to purchasing goods online on the smartphone – does not leverage quantum technology. The electronic transmission of the personal identification number (PIN) or password can be intercepted, posing a security risk.

Roughly 3mm in size, the tiny chip developed by NTU scientists uses quantum communication algorithms to provide enhanced security compared to existing standards. It does this by integrating passwords within the information that is being delivered, forming a secure ‘quantum key’. After the information is received, it is destroyed along with the key, making it an extremely secure form of communication.

It also needs 1,000 times less space than current quantum communication setups that can be as big as a refrigerator or even take up the space of an entire room or office floor. This opens doors for more secure communication technologies that can be deployed in compact devices such as smartphones, tablets and smart watches. It also lays the foundation for better encryption methods for online transactions and electronic communication.

Led by NTU Professor Liu Ai Qun, and Associate Professor Kwek Leong Chuan, the team’s findings were published in a leading peer-reviewed journal, Nature Photonics.

Prof Liu, who is from NTU’s School of Electrical and Electronic Engineering, said, “In today’s world, cyber security is very important as so much of our data are stored and communicated digitally. Almost all digital platforms and repositories require users to input their passwords and biometric data, and as long as this is the case, it could be eavesdropped on or deciphered. Quantum technology eliminates this as both the password and information are integrated within the message being sent, forming a ‘quantum key’.”

Assoc Prof Kwek explains that quantum communication works by using randomised strings of code to encrypt the information, which can only be opened by the intended recipient with the correct ‘key’. There is no need for additional passwords or biometric data to be transmitted, which is the standard practice in current forms of communication.

“It is like sending a secured letter. Imagine that the person who wrote the letter locked the message in an envelope with its ‘key’ also inside it. The recipient needs the same ‘key’ to open it. Quantum technology ensures that the key distribution is secure, preventing any tampering to the ‘key’”, said Assoc Prof Kwek, a physicist at NTU’s National Institute of Education.

Military-grade communication tech, made cost-effective

The world’s biggest tech companies such as Google and IBM are racing to develop quantum supercomputers that would revolutionise computing at speeds now inconceivable.

One highly anticipated strength of quantum technology lies in cryptography, the art of secret communication.

With the proliferation of Internet services, emails and messaging platforms such as WhatsApp, Facebook, Skype, Snapchat, Telegram etc., have created their own secured channels for communication – what is known as “classical channels”.

In contrast, “quantum channels” that carry information have security protocols that are integrated into the encrypted data. Each channel is uniquely different from each other, reducing or even eliminating the risk of information being intercepted or leaked during transmission.

Simply put, quantum technology does not require additional transmissions of passwords or biometric data that is necessary in “classical channels”. This eliminates the risk of interception or information being leaked, creating an almost unbreakable encryption.

The quantum communication chip developed by the NTU researchers will be cost effective as it uses standard industry materials such as silicon, which also makes it easy to manufacture.

Prof Liu said, “This is the future of communication security and our research brings us closer to quantum computing and communication. It will help spark the creation of next-generation communication devices, as well as enhance digital services such as online financial portals of banks, and digital government services.”

The NTU team is now looking to develop a hybrid network of traditional optical communication systems and quantum communication systems. This will improve the compatibility of quantum technologies that can be used in a wider range of applications such as internet connectivity.

Learn more: ?NTU Singapore researchers develop quantum communication chip 1,000 times smaller than current setups

 

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Bringing humans and robots closer together using game theory

Robots are being used in a range of industries including manufacturing but rarely work collaboratively with humans. New research from the University of Sussex, Imperial College London and Nanyang Technological University could change all that.

Researchers at the University of Sussex, Imperial College London and Nanyang Technological University in Singapore have for the first time used game theory to enable robots to assist humans in a safe and versatile manner.

The research team used adaptive control and Nash equilibrium game theory to programme a robot that can understand its human user’s behaviour in order to better anticipate their movements and respond to them.

The researchers believe the breakthrough could help robots complementing humans for sport training, physical rehabilitation or shared driving.

Lead author Dr Yanan Li, Lecturer in Control Engineering at the University of Sussex, said: “It is still very early days in the development of robots and at present, those that are used in a working capacity are not intuitive enough to work closely and safely with human users. By enabling the robot to identify human users’ behaviour and exploiting game theory to let the robot optimally react to them, we have developed a system where robots can work along humans as humans do.”

In a paper published today in Nature Machine Intelligence, the researchers outline how they adapted game theory for the physical interaction of a robot with a human, and how this can be used to help an impaired stroke survivor retrain their motor control.

Game theory is commonly used to understand how economic agents decide and interact with each other in order to maximise their own gain. To successfully apply game theory to the interaction of a robot and its human user, the researchers had to overcome the issue that the robot cannot know the human’s intentions. The researchers thus had to develop a method enabling the robot to identify the human partner while safely and efficiently interacting with their motion.

The reactive robotic programming system enables a robot to continuously learn the human user’s control and adapt its own control correspondingly. The robot is able to understand the human user’s action and then respond to and assist them to perform tasks successfully and with minimal effort.

Professor Etienne Burdet, Chair in Human Robotics in the Department of Bioengineering at Imperial College London and senior author of the paper, added: “Game theory has had important impacts in economics during the last century and lead to several Nobel prizes such as Nash’s one. To apply it for human-robot interaction, it was necessary to understand how the robot can identify the human user’s control goals simultaneously to smoothly interacting with them.”

Learn more: How game theory can bring humans and robots closer together

 

 

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A smart handheld diagnostic device could allow early intervention for people with congestive heart failure

Device detects excess fluid in lungs, a common symptom of congestive heart failure

A research team from Nanyang Technological University, Singapore (NTU Singapore) and Tan Tock Seng Hospital (TTSH) have invented a smart handheld medical device that could enable early intervention for patients with congestive heart failure.

The portable innovation, which resembles a stethoscope, is made up of an acoustic sensor connected to a smartphone. It enables early intervention by allowing patients to check for excess fluid in the lungs at home. Fluid accumulation in the lungs, which causes breathlessness, is a common symptom of congestive heart failure.

One in five people worldwide run the risk of developing congestive heart failure, and this prevalence increases with age. As there is no cure for the ailment, patients can only monitor their health closely with lifestyle changes or medication to prevent their heart function from deteriorating irreversibly.

Currently, patients can only check for fluid accumulation in the lungs by going for a clinical examination, which can be considerably subjective, or through imaging modalities and serum biomarker tests, which are costly and take a longer time.

The non-invasive device built by a team led by NTU Associate Professor Ser Wee and TTSH Associate Professor David Foo circumvents these problems with its portability, ease of use and quick results. Currently a prototype, the device is able to detect any excess fluid in the lungs in 10 seconds once placed on the patient’s chest or back.

In a pilot study using lung sounds recorded from TTSH’s congestive heart failure patients, Assoc Prof Ser and his team found the device to have over 92 per cent accuracy in identifying patients with the condition – comparable to existing ‘gold standard’ diagnosis methods such as X-rays and CT scans. The findings were first presented at the 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

Associate Professor Foo, Head of Cardiology at TTSH, said, “Patients can monitor their condition at home and use the device whenever they feel slightly breathless at home. It is potentially a game-changer in the management of ambulatory heart failure patients. It can also provide a rapid and accurate acute diagnosis of heart failure in situations of undifferentiated shortness of breath symptoms.”

Associate Professor Ser from NTU’s School of Electrical and Electronic Engineering added, “Currently, such diagnosis can only be conducted through clinical examination, which cannot be made frequently. Our smart medical device can be used by anyone, anywhere and any number of times, which will enable the possibility of early intervention of congestive heart failure.

“The next wave of MedTech (medical technology) start-ups will see the massive proliferation of smart medical devices that rely on artificial intelligence (AI) and sensing technologies, such as the one we invented, and that will enable personalised self-assessment and screening of cardiopulmonary and other diseases, and revolutionise the way healthcare is managed in future.”

How it works

In congestive heart failure, the diseased or overworked heart ventricle is unable to pump out enough of the blood it receives from the lungs. This causes pressure to build up first in the heart, then in the veins and capillaries in the lungs. The pressure then pushes fluid back through the capillary walls and into the air sacs of the lungs.

As a result, when air passes through these fluid-filled air sacs, crackles can be heard from the lungs. Depending on the intensity, a crackle may sound like salt added to a hot pan, or Velcro being torn apart. Based on this principle, Prof Ser and his team found a unique set of features that can be used to identify characteristics of sounds unique to patients with fluid accumulation in the lungs. They then developed a proprietary AI algorithm capable of identifying and processing these signals to determine if there is fluid accumulation in the lungs.

The smart medical device developed by NTU and TTSH first picks up breathing sounds through a sound sensor. Through a mobile app, the sound signals are then sent to a server located in the cloud. The NTU-developed algorithm stored in the cloud then processes these sound signals, and the results are shown on the mobile app. This whole process takes about 10 seconds to complete.

Following two rounds of tests with samples collected from 86 patients, the team is now running a third round of tests on the device to further validate its sensitivity and specificity.

A major pharmaceutical company, a healthcare MNC and a local healthcare company have approached the team to explore the possibility of collaborations.

Learn more: ?NTU Singapore and TTSH invent smart medical device for early intervention of congestive heart failure

 

 

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