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Category: nanotechnology – Page 160

The ever-increasing production and use of plastics over the last half century has created a huge environmental problem for the world. Currently, most of the 4.9 billion tonnes of plastics ever produced will end up in landfills or the natural environment, and this number is expected to increase to around 12 billion tonnes by 2050.

In collaboration with colleagues at universities and institutions in the UK, China and the Kingdom of Saudi Arabia, researchers in the Edwards/ Xiao group at Oxford’s Department of Chemistry have developed a method of converting plastic waste into hydrogen gas which can be used as a clean fuel, and high-value solid carbon. This was achieved with a new type of catalysis developed by the group which uses microwaves to activate catalyst particles to effectively ‘strip’ hydrogen from polymers.

The findings, published in Nature Catalysis, detail how the researchers mixed mechanically-pulverised plastic particles with a microwave-susceptor catalyst of iron oxide and aluminium oxide. The mixture was subjected to microwave treatment and yielded a large volume of hydrogen gas and a residue of carbonaceous materials, the bulk of which were identified as carbon nanotubes.

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Researchers from Rice University claim that processing boron nitride nanotubes used to be challenging, but not anymore.

Professors Matteo Pasquali and Angel Martí, along with their team of researchers, have simplified the handling of the highly valuable nanotubes, making them more suited for use in large-scale applications including electronics, aerospace, and energy-efficient materials.

According to the study’s findings published in Nature Communications, boron nitride nanotubes, also known as BNNTs, can self-assemble into liquid crystals when exposed to certain circumstances, particularly concentrations of chlorosulfonic acid that are greater than 170 parts per million by weight.

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Nanotechnologist and co-founder of the Black in Nanotech initiative, Olivia Geneus. (Courtesy: Alexander Harold) Welcome to this Physics World Nanotechnology Briefing, which showcases the breadth of applications of modern nanotechnology.

Olivia Geneus is one of the growing number of scientists who are developing nanotechnologies for medicine. In an interview, the PhD student at the State University of New York at Buffalo explains how she is developing nanoparticles designed to cross the blood–brain barrier in order to image and destroy brain cancer cells. Geneus also talks about Black in Nanotech Week, which she co-founded, and the need to encourage Black children to consider careers in science.

Ed Lester of the UK’s University of Nottingham knows that there are myriad uses for nanoparticles. In 2007 he founded the company Promethean Particles when he realized industrial users were not able to source nanoparticles in the quantities and quality that they required. In an interview, Lester talks about some of the company’s development projects including nanoparticles for aviation, healthcare and energy.

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Next big thing Haifei Zhan and colleagues reckon that carbon nanothreads have a future in energy storage. (Courtesy: Queensland University of Technology) Computational and theoretical studies of diamond-like carbon nanothreads suggest that…

Computational and theoretical studies of diamond-like carbon nanothreads suggest that they could provide an alternative to batteries by storing energy in a strained mechanical system. The team behind the research says that nanothread devices could power electronics and help with the shift towards renewable sources of energy.

The traditional go-to device for energy storage is the electrochemical battery, which predates even the widespread use of electricity. Despite centuries of technological progress and near ubiquitous use, batteries remain prone to the same inefficiencies and hazards as any device based on chemical reactions – sluggish reactions in the cold, the danger of explosion in the heat and the risk of toxic chemical leakages.

Another way of storing energy is to strain a material that then releases energy as it returns to its unstrained state. The strain could be linear like stretching and then launching a rubber band from your finger; or twisted, like a wind-up clock or toy. More than a decade ago, theoretical work done by researchers at the Massachusetts Institute of Technology suggested that strained chords made from carbon nanotubes could achieve impressive energy-storage densities, on account of the material’s unique mechanical properties.

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A method of optically selecting and sorting nanoparticles according to their quantum mechanical properties has been developed by researchers in Japan. The method could prove a crucial tool for manufacturing nanostructures for quantum sensing, biological imaging and quantum information technology ( Sci. Adv. 7 eabd9551).

Scientists have several ways of manipulating and positioning tiny objects without touching them. Optical tweezers, for example, use a highly focused laser beam to generate optical forces that hold and move objects in the beam’s trajectory. However, such tweezers struggle to grasp nanoparticles because these tiny objects are much smaller than the wavelength of the laser light used.

Now, a team led by Hajime Ishihara of Osaka University and Keiji Sasaki at Hokkaido University has developed a way of using light to sort nanodiamonds. These are tiny pieces of semiconductor with very useful optoelectronic properties that derive from bulk diamond as well as certain defects such as nitrogen-vacancy (NV) centres.

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An electrochemically powered artificial muscle made from twisted carbon nanotubes contracts more when driven faster thanks to a novel conductive polymer coating. Developed by Ray Baughman of the University of Texas at Dallas in the US and an international team, the device overcomes some of the limitations of previous artificial muscles, and could have applications in robotics, smart textiles and heart pumps.

Carbon nanotubes (CNTs) are rolled-up sheets of carbon with walls as thin as a single atom. When twisted together to form a yarn and placed in an electrolyte bath, CNTs expand and contract in response to electrochemical inputs, much like a natural muscle. In a typical set-up, a potential difference between the yarn and an electrode drives ions from the electrolyte into the yarn, causing the muscle to actuate.

While such CNT muscles are highly energy efficient and extremely strong – they can lift loads up to 100,000 times their own weight – they do have limitations. The main one is that they are bipolar, meaning that the direction of their movement switches whenever the potential drops to zero. This reduces the overall stroke of the actuator. Another drawback is that the muscle’s capacitance decreases when the potential is changed quickly, which also causes the stroke to decrease.

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Researchers in the US, Poland and Korea have observed photon avalanching – a chain-reaction-like process in which the absorption of a single photon triggers the emission of many – in tiny crystals just 25–30 nm in diameter. This highly nonlinear phenomenon had previously only been seen in bulk materials, and team leader James Schuck says that replicating it in nanoparticles could lead to “revolutionary new applications” in imaging, sensing and light detection (Nature 589 230).

Photon avalanching involves a process known as upconversion, whereby the energy of the emitted photons is higher than the energy of the photons that triggered the avalanche. Materials based on lanthanides (chemical elements with atomic numbers between 57 and 71) can support this process in part because their internal atomic structure enables them to store energy for long periods of time. Even so, achieving photon avalanching in lanthanide systems is difficult because high concentrations of lanthanide ions are needed to keep the avalanche going, and the relatively large volume of material required has previously restricted applications.

In the latest work, Schuck and colleagues at Columbia University, together with collaborators at Lawrence Berkeley National Laboratory, the Polish Academy of Sciences and Sungkyunkwan University, observed photon avalanching in lanthanide nanocrystals after exciting them with a laser at near-infrared wavelengths of either 1,064 or 1450 nm. The crystals are based on sodium yttrium fluoride in which 8% of the yttrium ions have been replaced with thulium. This doping fraction is much higher than the 0.2–1% typically found in previous work on photon avalanching.

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When water vapour spontaneously condenses inside capillaries just 1 nm thick, it behaves according to the 150-year-old Kelvin equation – defying predictions that the theory breaks down at the atomic scale. Indeed, researchers at the University of Manchester have showed that the equation is valid even for capillaries that accommodate only a single layer of water molecules (Nature 588 250).

Condensation inside capillaries is ubiquitous and many physical processes – including friction, stiction, lubrication and corrosion – are affected by it. The Kelvin equation relates the surface tension of water to its temperature and the diameter of its meniscus. It predicts that if the ambient humidity is between 30–50%, then flat capillaries less than 1.5 nm thick will spontaneously fill with water that condenses from the air.

Real world capillaries can be even smaller, but for them it is impossible to define the curvature of a liquid’s meniscus so the Kelvin equation should no longer hold. However, because such tight confinement is difficult to achieve in the laboratory, this had yet to be tested.

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Professor Pattie Maes deep insights working with her research team of Joanne Leong, Pat Pataranutaporn, Valdemar Danry are world leading in their translational research on tech-human interaction. Their highly interdisciplinary work covering decades of MIT Lab pioneering inventions integrates human computer interaction (HCI), sensor technologies, AI / machine learning, nano-tech, brain computer interfaces, design and HCI, psychology, neuroscience and much more. I participated in their day-long workshop and followed-up with more than three hours of interviews of which over an hour is transcribed in this article. All insights in this article stem from my daily pro bono work with (now) more than 400,000 CEOs, investors, scientists/experts. MIT Media Lab Fluid Interfaces research team work is particularly key with the June 21 announcement of the Metaverse Standards Forum, a open standards group, with big tech supporting such as Microsoft and Meta, chaired by Neil Trevett, Khronos President and VP Developer Ecosystems at NVIDIA. I have a follow-up interview with Neil and Forbes article in the works. In addition, these recent announcements also highlight why Pattie Maes work is so important: Deep Mind’s Gato multi-modal, multi-task, single generalist agent foundational to artificial general intelligence (AGI); Google’s LaMDA Language Model for Dialogue Applications which can engage in free-flowing dialogue; Microsoft’s Build Conference announcements on Azure AI and OpenAI practical tools / solutions and responsible AI; OpenAI’s DALL-E 2 producing realistic images and art from natural language descriptions.

Full Story:

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As they grow, solid tumors surround themselves with a thick, hard-to-penetrate wall of molecular defenses. Getting drugs past that barricade is notoriously difficult. Now, scientists at UT Southwestern have developed nanoparticles that can break down the physical barriers around tumors to reach cancer cells. Once inside, the nanoparticles release their payload: a gene editing system that alters DNA inside the tumor, blocking its growth and activating the immune system.

The new , described in Nature Nanotechnology, effectively stopped the growth and spread of ovarian and liver tumors in mice. The system offers a new path forward for the use of the gene editing tool known as CRISPR-Cas9 in , said study leader Daniel Siegwart, Ph.D., Associate Professor of Biochemistry at UT Southwestern.

“Although CRISPR offers a new approach for treating , the technology has been severely hindered by the low efficiency of delivering payloads into tumors,” said Dr. Siegwart, a member of the Harold C. Simmons Comprehensive Cancer Center.

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