Elusive 3D printed nanoparticles could lead to new shapeshifting materials

Optical images of truncated tetrahedrons forming two large hexagonal grains at an anti-phase boundary (left), and transforming into a quasi-diamond phase that initiated at the anti-phase boundary (right). Scale bars are 25 um.
Image Credit: David Doan & John Kulikowski

Stanford materials engineers have 3D printed tens of thousands of hard-to-manufacture nanoparticles long predicted to yield promising new materials that change form in an instant.

In nanomaterials, shape is destiny. That is, the geometry of the particle in the material defines the physical characteristics of the resulting material.

“A crystal made of nano-ball bearings will arrange themselves differently than a crystal made of nano-dice and these arrangements will produce very different physical properties,” said Wendy Gu, an assistant professor of mechanical engineering at Stanford University, introducing her latest paper which appears in the journal Nature Communications. “We’ve used a 3D nanoprinting technique to produce one of the most promising shapes known – Archimedean truncated tetrahedrons. They are micron-scale tetrahedrons with the tips lopped off.”

In the paper, Gu and her co-authors describe how they nanoprinted tens of thousands of these challenging nanoparticles, stirred them into a solution, and then watched as they self-assembled into various promising crystal structures. More critically, these materials can shift between states in minutes simply by rearranging the particles into new geometric patterns.

This ability to change “phases,” as materials engineers refer to the shapeshifting quality, is similar to the atomic rearrangement that turns iron into tempered steel, or in materials that allow computers to store terabytes of valuable data in digital form.

“If we can learn to control these phase shifts in materials made of these Archimedean truncated tetrahedrons it could lead in many promising engineering directions,” she said.

Novel electrochemical sensor detects dangerous bacteria

By using a customized surface to bait the targeted pathogens, they separate by themselves from a mixture of many different bacteria. This makes it easy to detect them electrochemically.
Illustration Credit: Sebastian Balser, Andreas Terfort Research Group, Goethe University Frankfurt

Researchers at Goethe University Frankfurt and Kiel University have developed a novel sensor for the detection of bacteria. It is based on a chip with an innovative surface coating. This ensures that only very specific microorganisms adhere to the sensor – such as certain pathogens. The larger the number of organisms, the stronger the electric signal generated by the chip. In this way, the sensor is able not only to detect dangerous bacteria with a high level of sensitivity but also to determine their concentration. 

Each year, bacterial infections claim several million lives worldwide. That is why detecting harmful microorganisms is crucial – not only in the diagnosis of diseases but also, for example, in food production. However, the methods available so far are often time-consuming, require expensive equipment or can only be used by specialists. Moreover, they are often unable to distinguish between active bacteria and their decay products. 

By contrast, the newly developed method detects only intact bacteria. It makes use of the fact that microorganisms only ever attack certain body cells, which they recognize from the latter's specific sugar molecule structure. This matrix, known as the glycocalyx, differs depending on the type of cell. It serves, so to speak, as an identifier for the body cells. This means that to capture a specific bacterium, we need only to know the recognizable structure in the glycocalyx of its preferred host cell and then use this as “bait".

‘Winners and losers’ as global warming forces plants uphill

Cerrado savanna in the Chapada dos Veadeiros National Park, Brazil.
Photo Credit Ana Christina

Some plant species will “win” and others will “lose” as global warming forces them to move uphill, new research shows.

Scientists examined the current range of more than 7,000 plant species in Brazil’s Cerrado savanna, and estimated shifts based on warming by 2040.

The fate of plant species will depend on where they live: lowland species can move uphill for cooler conditions, but mountain plants have nowhere to go.

The study was carried out by the universities of Exeter and Campinas, the Royal Botanic Garden Edinburgh and Trinity College Dublin.

“Every plant and animal species has a ‘geographical range’ – the area where conditions are suitable for it to live,” said Mateus Silva, from the University of Exeter.

“As the climate warms, plants’ ranges are shifting, with many species going uphill.

“This is the pattern we found in the Cerrado – suggesting lowland areas may become local extinction hotspots, while mountains will host new combinations of plant species.”

CBD products don’t ease pain and are potentially harmful – new study finds

CBD oil may be popular for treating pain but taking it appears to be a waste of money
Photo Credit: Julia Teichmann

There is no evidence that CBD products reduce chronic pain, and taking them is a waste of money and potentially harmful to health, according to new research led by the University of Bath.

CBD (short for cannabidiol) is one of many chemicals found naturally in the cannabis plant. It’s a popular alternative treatment for pain and is readily available in shops and online in the form of oils, tinctures, vapes, topical creams, edibles (such as gummy bears) and soft drinks.

However, consumers would do well to steer clear of these products, according to the new study.

“CBD presents consumers with a big problem,” said Professor Chris Eccleston, who led the research from the Centre for Pain Research at Bath. “It’s touted as a cure for all pain but there’s a complete lack of quality evidence that it has any positive effects.”

He added: “It’s almost as if chronic pain patients don’t matter, and that we’re happy for people to trade on hope and despair.”

For their study, published this week in The Journal of Pain, the team – which included researchers from the Universities of Bath, Oxford and Alberta in Canada – examined research relevant to using CBD to treat pain and published in scientific journals up to late 2023.

SwRI Develops More Effective Particle Conversion Surfaces for Space Instruments

SwRI space scientists are collaborating with materials specialists to create more effective particle detection surfaces for spacecraft instruments. Pictured is a conversion surface substrate developed specifically for the IMAP-Lo instrument.
Photo Credit: Courtesy of SwRI

Southwest Research Institute is investing internal funding to develop more effective conversion surfaces to allow future spacecraft instruments to collect and analyze low-energy particles. Conversion surfaces are ultra-smooth, ultra-thin surfaces covering a silicon wafer that converts neutral atoms into ions to more effectively detect particles from outer space.

Changing the charge of particles simplifies and enhances detection and analysis capabilities. Dr. Jianliang Lin of the Institute’s Mechanical Engineering Division and Dr. Justyna Sokół of SwRI’s Space Science Division lead the multidisciplinary project. The project builds on the successful creation of conversion surfaces for the IMAP-Lo instrument for the Interstellar Mapping and Acceleration Probe (IMAP) spacecraft. IMAP, which is set to launch in 2025, will help researchers better understand the boundary of our heliosphere, the region of space encompassing the solar system, where the solar wind has a significant influence.

“When low-energy atoms enter the instrument from outer space, they bounce off the conversion surface and either gain or lose an electron, making their electrical charge unbalanced. This makes it easier to increase their speed and analyze their mass and other properties,” Sokół said.

Honey bees at risk for colony collapse from longer, warmer fall seasons

WSU researchers and students collect samples and perform honey bee colony health assessments in orchards near Modesto, CA.
Photo Credit: Brandon Hopkins

The famous work ethic of honey bees might spell disaster for these busy crop pollinators as the climate warms, new research indicates.

Flying shortens the lives of bees, and worker honey bees will fly to find flowers whenever the weather is right, regardless of how much honey is already in the hive. Using climate and bee population models, researchers found that increasingly long autumns with good flying weather for bees raises the likelihood of colony collapse in the spring.

The study, published in the journal Scientific Reports, focused on the Pacific Northwest but holds implications for hives across the U.S. The researchers also modeled a promising mitigation: putting colonies into indoor cold storage, so honey bees will cluster in their hive before too many workers wear out.

“This is a case where a small amount of warming, even in the near future, will make a big impact on honey bees,” said lead author Kirti Rajagopalan, a Washington State University climate researcher. “It’s not like this is something that can be expected 80 years from now. It is a more immediate impact that needs to be planned for.”

Persian plateau unveiled as crucial hub for early human migration out of Africa

Pebdeh Cave located in the southern Zagros Mountains. Pebdeh was occupied by hunter-gatherers as early as 42,000 years ago.
Photo Credit: Mohammad Javad Shoaee

A new study combining genetic, palaeoecological, and archaeological evidence has unveiled the Persian plateau as a pivotal geographic location serving as a hub for Homo sapiens during the early stages of their migration out of Africa.  

This study sheds new light on the complex journey of human populations, challenging previous understandings of our species’ expansion into Eurasia. 

The study, published in Nature Communications, highlights a period between 70,000 to 45,000 years ago when human populations did not uniformly spread across Eurasia, leaving a gap in our understanding of their whereabouts during this time frame. 

Large language models use a surprisingly simple mechanism to retrieve some stored knowledge

Caption:Researchers from MIT and elsewhere found that complex large language machine-learning models use a simple mechanism to retrieve stored knowledge when they respond to a user prompt. The researchers can leverage these simple mechanisms to see what the model knows about different subjects, and also possibly correct false information that it has stored.
Image Credit: Copilot / DALL-E 3 / AI generated from Scientific Frontline prompts

Large language models, such as those that power popular artificial intelligence chatbots like ChatGPT, are incredibly complex. Even though these models are being used as tools in many areas, such as customer support, code generation, and language translation, scientists still don’t fully grasp how they work.

In an effort to better understand what is going on under the hood, researchers at MIT and elsewhere studied the mechanisms at work when these enormous machine-learning models retrieve stored knowledge.

They found a surprising result: Large language models (LLMs) often use a very simple linear function to recover and decode stored facts. Moreover, the model uses the same decoding function for similar types of facts. Linear functions, equations with only two variables and no exponents, capture the straightforward, straight-line relationship between two variables.

The researchers showed that, by identifying linear functions for different facts, they can probe the model to see what it knows about new subjects, and where within the model that knowledge is stored.

A self-cleaning wall paint

Qaisar Maqbool and Günther Rupprechter
Photo Credit: Courtesy of Technische Universität Wien

A breakthrough in catalysis research leads to a new wall paint that cleans itself when exposed to sunlight and chemically breaks down air pollutants.

Typically, beautiful white wall paint does not stay beautiful and white forever. Often, various substances from the air accumulate on its surface. This can be a desired effect because it makes the air cleaner for a while – but over time, the color changes and needs to be renewed.

A research team from TU Wien and the Università Politecnica delle Marche (Italy) has now succeeded in developing special titanium oxide nanoparticles that can be added to ordinary, commercially available wall paint to establish self-cleaning power: The nanoparticles are photocatalytically active, they can use sunlight not only to bind substances from the air, but also to decompose them afterwards. The wall makes the air cleaner – and cleans itself at the same time. Waste was used as the raw material for the new wall paint: metal scrap, which would otherwise have to be discarded, and dried fallen leaves.

New All-Liquid Iron Flow Battery for Grid Energy Storage

Lead author and battery researcher Gabriel Nambafu assembles a test flow battery apparatus.
Photo Credit:  Andrea Starr | Pacific Northwest National Laboratory

A commonplace chemical used in water treatment facilities has been repurposed for large-scale energy storage in a new battery design by researchers at the Department of Energy’s Pacific Northwest National Laboratory. The design provides a pathway to a safe, economical, water-based, flow battery made with Earth-abundant materials. It provides another pathway in the quest to incorporate intermittent energy sources such as wind and solar energy into the nation’s electric grid.

The researchers report in Nature Communications that their lab-scale, iron-based battery exhibited remarkable cycling stability over one thousand consecutive charging cycles, while maintaining 98.7 percent of its maximum capacity. For comparison, previous studies of similar iron-based batteries reported degradation of the charge capacity two orders of magnitude higher, over fewer charging cycles.

Iron-based flow batteries designed for large-scale energy storage have been around since the 1980s, and some are now commercially available. What makes this battery different is that it stores energy in a unique liquid chemical formula that combines charged iron with a neutral-pH phosphate-based liquid electrolyte, or energy carrier. Crucially, the chemical, called nitrogenous triphosphonate, nitrilotri-methylphosphonic acid or NTMPA, is commercially available in industrial quantities because it is typically used to inhibit corrosion in water treatment plants.