Lasers Could Cut Lifespan of Nuclear Waste from a Million Years to 30 Minutes

Whatever one thinks of nuclear energy, the process results in tons of radioactive, toxic waste no one quite knows what to do with. As a result, it’s tucked away as safely as possible in underground storage areas where it’s meant to remain a long, long time: The worst of it, uranium 235 and plutonium 239, have a half life of 24,000 years. That’s the reason eyebrows were raised in Europe — where more countries depend on nuclear energy than anywhere else — when physicist Gérard Mourou mentioned in his wide-ranging Nobel acceptance speech that lasers could cut the lifespan of nuclear waste from “a million years to 30 minutes,” as he put it in a followup interview with The Conversation.
Who is Gérard Mourou? Mourou was the co-recipient of his Nobel with Donna Strickland for their development of Chirped Pulse Amplification (CPA) at the University of Rochester. In his speech, he referred to his “passion for extreme light.”

CPA produces high-intensity, super-short optical pulses that pack a tremendous amount of power. Mourou’s and Strickland’s goal was to develop a means of making highly accurate cuts useful in medical and industrial settings. It turns out CPA has another benefit, too, that’s just as important. Its attosecond pulses are so quick that they shine a light on otherwise non-observable, ultra-fast events such as those inside individual atoms and in chemical reactions. This capability is what Mourou hopes give CPA a chance of neutralizing nuclear waste, and he’s actively working out a way to make this happen in conjunction with Toshiki Tajima of UC Irvine.

“Take the nucleus of an atom. It is made up of protons and neutrons. If we add or take away a neutron, it changes absolutely everything. It is no longer the same atom, and its properties will completely change. The lifespan of nuclear waste is fundamentally changed, and we could cut this from a million years to 30 minutes!,”  explains Mourou.

We are already able to irradiate large quantities of material in one go with a high-power laser, so the technique is perfectly applicable and, in theory, nothing prevents us from scaling it up to an industrial level. This is the project that I am launching in partnership with the Alternative Energies and Atomic Energy Commission, or CEA, in France. We think that in 10 or 15 years’ time we will have something we can demonstrate. This is what really allows me to dream, thinking of all the future applications of our invention.”

While 15 years may seem a long time, when you’re dealing with the half-life of nuclear waste, it’s a blink of an eye.

Source: https://www.freethink.com/

Lasers and Ultrasound Combine to Pulverize Arterial Plaque

Lasers are one of the tools physicians can lean on to tackle plaque buildup on arterial walls, but current approaches carry a risk of complications and can be limited in their effectiveness. By bringing ultrasound into the mix, scientists at the University of Kansas have demonstrated a new take on this treatment that relies on exploding microbubbles to destroy plaque with greater safety and efficiency, while hinting at some unique long-term advantages.

Scientists have demonstrated a new technique to take out arterial plaque, using low-power lasers and ultrasound to break it apart with tiny bubbles

The novel ultrasound-assisted laser technique builds off what’s known as laser angioplasty, an existing treatment designed to improve blood flow in patients suffering from plaque buildup that narrows the arteries. Where more conventional treatments such as stents and balloon angioplasty expand the artery and compress the plaque, laser angioplasty destroys it to eliminate the blockage.

The laser is inserted into the artery with a catheter, and the thermal energy it generates turns water in the artery into a vapor bubble that expands, collapses and breaks up the plaque. Because this technique calls for high-power lasers, it has the potential to perforate or dissect the artery, something the scientists are looking to avoid by using low-power lasers instead.

They were able to do so in pork belly samples and ex vivo samples of artery plaque with the help of ultrasound. The method uses a low-power nanosecond pulsed laser to generate microbubbles, and applying ultrasound to the artery then causes these microbubbles to expand, collapse and disrupt the plaque.

In conventional laser angioplasty, a high laser power is required for the entire cavitation process, whereas in our technology, a lower laser power is only required for initiating the cavitation process,” said team member Rohit Singh. “Overall, the combination of ultrasound and laser reduces the need for laser power and improves the efficiency of atherosclerotic plaque removal.

The mix of lasers and ultrasound has shown potential in other areas of medicine, with Singh and his colleagues pursuing similar therapies to tackle abnormal microvessels in the eye that cause blindness and blood clots in the veins. We’ve also seen ultrasound used to explode tiny bubbles in cancer research, providing a way of wiping out cancerous cells within a tumor.

Source: https://newatlas.com/

Smart Contact Lens to Treat Glaucoma

A flexible contact lens that senses eye pressure and releases a drug on-demand could help treat glaucoma, the second leading global cause of blindness worldwide. The compact wireless device, which has been developed by a team of Chinese researchers and tested in pig and rabbit eyes so far, appears to detect and reduce rising eye pressure, one of the usual causes of glaucoma.

Glaucoma is an umbrella term for a group of eye diseases where damage to the optic nerve, which relays visual information to the brain, causes irreversible vision loss and blindness in millions of people worldwide. Where this new research makes ground is in developing a device capable of detecting changes in eye pressure and delivering therapeutic drugs as needed. Recent efforts to develop smart contact lenses as wearable devices for treating eye conditions have either focused on sensing pressure changes in the eye or delivering a drug – but not both – and glaucoma treatment usually involves eye drops, laser therapy, or surgery to reduce eye pressure. While it sounds exciting, keep in mind that as scientists continue experimenting with all sorts of nifty devices for treating eye diseases, early detection of glaucoma and timely treatment remains vital.

Once detected, therapy for glaucoma can arrest or slow its deterioration in the majority of cases,” Jaimie Steinmetz, a research scientist at the Washington-based Institute for Health Metrics and Evaluation, and collaborators wrote in 2020 when analyzing the global burden of eye diseases, including glaucoma. But glaucoma is typically hard to catch because peripheral vision is the first to go, and devices used to diagnose the condition only provide snapshot measurements of intraocular pressure, which fluctuates with activity and sleep-wake cycles.

Hence the importance of improving systems of surveillance, highlighting risk among family members of cases, and effectiveness of care once treatment is initiated,” Steinmetz and co-authors stressThat said, contact lenses which sit snug against the eye hold great appeal for delivering therapies for eye conditions. But incorporating electrical circuits and sensors into small, flexible, curved, and ultra-thin contact lenses presents a serious engineering challenge. For something like this to work, it needs to be sensitive enough to detect pressure changes and release precise amounts of drug on demand – all without blocking vision and irritating the eye. “It is highly challenging to install an intricate theranostic system composited by multi-modules on a contact lens,” electrical engineer Cheng Yang of Sun Yat-Sen University and colleagues write in their paper.

3D-Printed Chicken

Who hasn’t dreamt of coming home after a long day and simply pressing a few buttons to get a hot, home-cooked 3D-printed meal, courtesy of one’s digital personal chef? It might make microwaves and conventional frozen TV dinners obsolete. Engineers at Columbia University are trying to make that fantasy a reality, and they’ve now figured out how to simultaneously 3D-print and cook layers of pureed chicken, according to a recent paper published in the journal npj Science of Food. Sure, it’s not on the same level as the Star Trek Replicator, which could synthesize complete meals on demand, but it’s a start.

Coauthor Hob Lipson runs the Creative Machines Lab at Columbia University, where the research was conducted. His team first introduced 3D printing of food items back in 2007, using the Fab@Home personal fabrication system to create multi-material edible 3D objects with cake frosting, chocolate, processed cheese, and peanut butter. However, commercial appliances capable of simultaneously printing and cooking food layers don’t exist yet. There have been some studies investigating how to cook food using lasers, and Lipson’s team thought this might be a promising avenue to explore further.

We noted that, while printers can produce ingredients to millimeter precision, there is no heating method with this same degree of resolution,” said coauthor Jonathan Blutinger. “Cooking is essential for nutrition, flavor, and texture development in many foods, and we wondered if we could develop a method with lasers to precisely control these attributes.” They used a blue diode laser (5-10 watts) as the primary heating source but also experimented with lasers in the near- and mid-infrared for comparison, as well as a conventional toaster oven.

The scientists purchased raw chicken breast from a local convenience store and then pureed it in a food processor to get a smooth, uniform consistency. They removed any tendons and refrigerated the samples before repackaging them into 3D-printing syringe barrels to avoid clogging. The cooking apparatus used a high-powered diode laser, a set of mirror galvanometers (devices that detect electrical current by deflecting light beams), a fixture for custom 3D printing, laser shielding, and a removable tray on which to cook the 3D-printed chicken.

During initial laser cooking, our laser diode was mounted in the 3D-printed fixture, but as the experiments progressed, we transitioned to a setup where the laser was vertically mounted to the head of the extrusion mechanism,” the authors wrote. “This setup allowed us to print and cook ingredients on the same machine.” They also experimented with cooking the printed chicken after sealing it in plastic packaging.

The results? The laser-cooked chicken retained twice as much moisture as conventionally cooked chicken, and it shrank half as much while still retaining similar flavors. But different types of lasers produced different results. The blue laser proved ideal for cooking the chicken internally, beneath the surface, while the infrared lasers were better at surface level browning and broiling. As for the chicken in plastic packaging, the blue laser did achieve slight browning, but the near-infrared laser was more efficient at browning the chicken through the packaging. The team was even able to brown the surface of the packaged chicken in a pattern reminiscent of grill marks.

Millimeter-scale precision allows printing and cooking a burger that has a level of doneness varying from rare to well-done in a lace, checkerboard, gradient, or other custom pattern,” the authors explained. “Heat from a laser can also cook and brown foods within a sealed package … [which] could significantly increase their shelf life by reducing their microbial contamination, and has great commercial applications for packaged to-go meals at the grocery store, for example.” To make sure the 3D-printed chicken still appealed to the human palate, the team served samples of both 3D-printed laser cooked and conventionally cooked chicken to two taste testers. It’s not a significant sample size, but both taste testers preferred the laser-cooked chicken over the conventionally cooked chicken, mainly because it was less dry and rubbery and had a more pleasing texture.

Source: https://www.wired.com/

How To Purify Water Without Wasting Energy

Amid the coronavirus pandemic, people in developed countries are assured of ample supplies of clean water to wash their hands as often as needed to protect themselves from the virus. And yet, nearly a third of the world’s population is not even assured of clean water for drinking. University of Rochester researchers have now found a way to address this problem by using sunlight—a resource that everyone can access—to evaporate and purify contaminated water with greater than 100 percent efficiency.

How is this possible? In a paper in Nature Sustainability, researchers in the laboratory of Chunlei Guo, professor of optics, demonstrate how a burst of femtosecond laser pulses etch the surface of a normal sheet of aluminum into a superwicking (water-attracting), super energyabsorbing material. Using sunlight to boil has long been recognized as a way to eliminate microbial pathogens and reduce deaths from diarrheal infections. But boiling water does not eliminate heavy metals and other contaminants. Experiments by the lab show that their new method reduces the presence of all common contaminants, such as detergent, dyes, urine, heavy metals, and glycerin, to safe levels for drinking.

Solar-based water purification can greatly reduce contaminants because nearly all the impurities are left behind when the evaporating water becomes gaseous and then condenses and gets collected. The most common method of solar-based water evaporation is volume heating, in which a large volume of water is heated but only the top layer can evaporate. This is obviously inefficient, Guo says, because only a small fraction of the heating energy gets used. A more efficient approach, called interfacial heating, places floating, multilayered absorbing and wicking materials on top of the water, so that only water near the surface needs to be heated. But the available materials all have to float horizontally on top of the water and cannot face the sun directly. Furthermore, the available wicking materials become quickly clogged with contaminants left behind after evaporation, requiring frequent replacement of the materials.

The panel developed by the Guo lab avoids these inefficiencies by pulling a thin layer of water out of the reservoir and directly onto the solar absorber surface for heating and evaporation. “Moreover, because we use an open-grooved surface, it is very easy to clean by simply spraying it,” Guo says.

The biggest advantage,” he adds, “is that the angle of the panels can be continuously adjusted to directly face the sun as it rises and then moves across the sky before setting” —maximizing energy absorption. “There was simply nothing else resembling what we can do here,” Guo says.

Source: https://www.rochester.edu/

Photonic Chips

Emitting light from silicon has been the ‘Holy Grail’ in the microelectronics industry for decades. Solving this puzzle would revolutionize computing, as chips will become faster than ever. Researchers from Eindhoven University of Technology  (TU-e) now succeeded: they have developed an alloy with silicon that can emit light. The team will now start creating a silicon laser to be integrated into current chips.

Every year we use and produce significantly more data. But our current technology, based on electronic chips, is reaching its ceiling. The limiting factor is heat, resulting from the resistance that the electrons experience when traveling through the copper lines connecting the many transistors on a chip. If we want to continue transferring more and more data every year, we need a new technique that does not produce heat. Bring in photonics, which uses photons (light particles) to transfer data. In contrast to electrons, photons do not experience resistance. As they have no mass or charge, they will scatter less within the material they travel through, and therefore no heat is produced. The energy consumption will therefore be reduced. Moreover, by replacing electrical communication within a chip by optical communication, the speed of on-chip and chip-to-chip communication can be increased by a factor 1000. Data centers would benefit most, with faster data transfer and less energy usage for their cooling system. But these photonic chips will also bring new applications within reach. Think of laser-based radar for self-driving cars and chemical sensors for medical diagnosis or for measuring air and food quality.

To use light in chips, you will need a light source; an integrated laser. The main semiconductor material that computer chips are made of is silicon. But bulk silicon is extremely inefficient at emitting light, and so was long thought to play no role in photonics. Thus, scientists turned to more complex semiconductors, such as gallium arsenide and indium phosphide. These are good at emitting light but are more expensive than silicon and are hard to integrate into existing silicon microchips.

To create a silicon compatible laser, scientists needed to produce a form of silicon that can emit light. That’s exactly what researchers from Eindhoven University of Technology (TU/e) now succeeded in. Together with researchers from the universities of Jena, Linz and Munich, they combined silicon and germanium in a hexagonal structure that is able to emit light. A breakthrough after 50 years of work.

Nanowires with hexagonal silicon-germanium shells

The crux is in the nature of the so-called band gap of a semiconductor,” says lead researcher Erik Bakkers from TU/e. “If an electron ‘drops’ from the conduction band to the valence band, a semiconductor emits a photon: light.” But if the conduction band and valence band are displaced with respect to each other, which is called an indirect band gap, no photons can be emitted – as is the case in silicon. “A 50-year old theory showed however that silicon, alloyed with germanium, shaped in a hexagonal structure does have a direct band gap, and therefore potentially could emit light,” explains Bakkers.

Shaping silicon in a hexagonal structure, however, is not easy. As Bakkers and his team master the technique of growing nanowires, they were able to create hexagonal silicon in 2015. They realized pure hexagonal silicon by first growing nanowires made from another material, with a hexagonal crystal structure. Then they grew a silicon-germanium shell on this template. Elham Fadaly, shared first author of the study: “We were able to do this such that the silicon atoms are built on the hexagonal template, and by this forced the silicon atoms to grow in the hexagonal structure.” But they could not yet make them to emit light, until now. Bakkers team managed to increase the quality of the hexagonal silicon-germanium shells by reducing the number of impurities and crystal defects. When exciting the nanowire with a laser, they could measure the efficiency of the new material. Alain Dijkstra, also shared first author of the study and responsible for measuring the light emission: “Our experiments showed that the material has the right structure, and that it is free of defects. It emits light very efficiently.”

The findings have been published in the journal Nature.

Source: https://www.tue.nl/

Laser Method Turns Any Metal Surface Into A Bacteria Killer

Bacterial pathogens can live on surfaces for days. What if frequently touched surfaces such as doorknobs could instantly kill them offPurdue University engineers have created a laser treatment method that could potentially turn any metal surface into a rapid bacteria killer – just by giving the metal’s surface a different texture. In a study published in the journal Advanced Materials Interfaces, the researchers demonstrated that this technique allows the surface of copper to immediately kill off superbugs such as MRSA.

A laser prepares to texture the surface of copper, enhancing its antimicrobial properties

Copper has been used as an antimicrobial material for centuries. But it typically takes hours for native copper surfaces to kill off bacteria,” said Rahim Rahimi, a Purdue assistant professor of materials engineering. “We developed a one-step laser-texturing technique that effectively enhances the bacteria-killing properties of copper’s surface.”

The technique is not yet tailored to killing viruses such as the one responsible for the COVID-19 pandemic, which are much smaller than bacteria. Since publishing this work, however, Rahimi’s team has begun testing this technology on the surfaces of other metals and polymers that are used to reduce risks of bacterial growth and biofilm formation on devices such as orthopedic implants or wearable patches for chronic wounds.

Source: https://www.purdue.edu/

Manipulating The “Boss Gene” For Reprogramming Humans

 

It seems like everything is going wireless these days. That now includes efforts to reprogram the human genome. A new University at Buffalo-led study describes how researchers wirelessly controlled FGFR1 — a gene that plays a key role in how humans grow from embryos to adults — in lab-grown brain tissue. The ability to manipulate the gene, the study’s authors say, could lead to new cancer treatments, and ways to prevent and treat mental disorders such as schizophrenia.

It represents a step forward toward genetic manipulation technology that could upend the treatment of cancer, as well as the prevention and treatment of schizophrenia and other neurological illnesses. It centers on the creation of a new subfield of research the study’s authors are calling “optogenomics,” or controlling the human genome through laser light and nanotechnology.

The left image shows the gene FGFR1 in its natural state. The right image shows the gene when exposed to laser light, which causes the gene to activiate and deactivate.

The potential of optogenomic interfaces is enormous,” says co-author Josep M. Jornet, PhD, associate professor in the Department of Electrical Engineering in the UB School of Engineering and Applied Sciences. “It could drastically reduce the need for medicinal drugs and other therapies for certain illnesses. It could also change how humans interact with machines.

For the past 20 years, scientists have been combining optics and genetics — the field of optogenetics — with a goal of employing light to control how cells interact with each other. By doing this, one could potentially develop new treatments for diseases by correcting the miscommunications that occur between cells. While promising, this research does not directly address malfunctions in genetic blueprints that guide human growth and underlie many diseases. The new research begins to tackle this issue because FGFR1 — it stands for Fibroblast Growth Factor Receptor 1 — holds sway over roughly 4,500 other genes, about one-fifth of the human genome, as estimated by the Human Genome Project, says study co-author Michal K. Stachowiak.

In some respects, it’s like a boss gene,” says Stachowiak, PhD, professor in the Department of Pathology and Anatomical Sciences in the Jacobs School of Medicine and Biomedical Sciences at UB. “By controlling FGFR1, one can theoretically prevent widespread gene dysregulations in schizophrenia or in breast cancer and other types of cancer.”

The work — spearheaded by UB researchers Josep M. Jornet, Michal K. Stachowiak, Yongho Bae and Ewa K. Stachowiak — was reported in the June edition of the Proceedings of the Institute of Electrical and Electronics Engineers.

Source: http://www.buffalo.edu/

Chinese ‘Death Star’ For Submarines

China is developing a satellite with a powerful laser for anti-submarine warfare that researchers hope will be able to pinpoint a target as far as 500 metres below the surface. It is the latest addition to the country’s expanding deep-sea surveillance programme, and aside from targeting submarines – most operate at a depth of less than 500 metres – it could also be used to collect data on the world’s oceansProject Guanlan, meaning “watching the big waves”, was officially launched in May at the Pilot National Laboratory for Marine Science and Technology in Qingdao, Shandong. It aims to strengthen China’s surveillance activities in the world’s oceans, according to the laboratory’s website.

Scientists are working on the satellite’s design at the laboratory, but its key components are being developed by more than 20 research institutes and universities across the country. Song Xiaoquan, a researcher involved in the project, said if the team can develop the satellite as planned, it will make the upper layer of the seamore or less transparent”. “It will change almost everything,” Song said.

While light dims 1,000 times faster in water than in the air, and the sun can penetrate no more than 200 metres below the ocean surface, a powerful artificial laser beam can be 1 billion times brighter than the sun. But this project is ambitious – naval researchers have tried for more than half a century to develop a laser spotlight for hunting submarines using technology known as light detection and ranging (lidar). In theory, it works like this – when a laser beam hits a submarine, some pulses bounce back. They are then picked up by sensors and analysed by computer to determine the target’s location, speed and three-dimensional shape.

But in real life, lidar technology can be affected by the device’s power limitations, as well as cloud, fog, murky water – and even marine life such as fish and whales. Added to that, the laser beam deflects and scatters as it travels from one body of water to another, making it more of a challenge to get a precise calculation. Experiments carried out by the United States and former Soviet Union achieved maximum detection depths of less than 100 metres, according to openly available information. That range has been extended in recent years by the US in research funded by Nasa and the Defence Advanced Research Projects Agency (DARPA).

Source: https://www.scmp.com/

How To Manipulate And Move Cells With Light

Wits physicists demonstrate a new device for manipulating and moving tiny objects with light. When you shine a beam of light on your hand, you don’t feel much, except for a little bit of heat generated by the beam. When you shine that same light into a world that is measured on the nano– or micro scale, the light becomes a powerful manipulating tool that you can use to move objects around – trapped securely in the light.

Researchers from the Structured Light group from the School of Physics at the University of the Witwatersrand in Johannesburg, South Africa, have found a way to use the full beam of a laser light, to control and manipulate minute objects such as single cells in a human body, tiny particles in small volume chemistry, or working on future on-chip devices. While the specific technique, called holographic optical trapping and tweezing, is not new, the Wits Researchers found a way to optimally use the full force of the light – including vector light that was previously unavailable for this application. This forms the first vector holographic trap.

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Previously holographic traps were limited to particular classes of light (scalar light), so it is very exciting that we can reveal a holistic device that covers all classes of light, including replicating all previous trapping devices,” explains Professor Andrew Forbes, team leader of the collaboration and Distinguished Professor in the School of Physics where he heads up the Wits Structured Light Laboratory.

What we have done is that we have demonstrated the first vector holographic optical trapping and tweezing system. The device allows micrometer sized particles, such as biological cells, to be captured and manipulated only with light.”

Source: https://www.wits.ac.za/