How are ancient Roman and Mayan buildings still standing? Scientists are unlocking their secrets
Oct 2023, phys.org
There's 2,000-year-old concrete still looking like the day it was poured. And there's also the front steps of my friend's apartment that's been crumbling since the day it got repaired.
What's the difference?
Some of these ancient builders might have just gotten lucky, said Cecilia Pesce, a materials scientist at the University of Sheffield in England. They'd toss just about anything into their mixes, as long as it was cheap and available—and the ones that didn't work out have long since collapsed.
"They would put all sorts of things in construction," Pesce said. "And now, we only have the buildings that survived. So it's like a natural selection process."
But alas, there does seem to be a pattern:
In a study published earlier this year, Admir Masic, a civil and environmental engineer at the Massachusetts Institute of Technology, proposed that this power comes from chunks of lime that are studded throughout the Roman material instead of being mixed in evenly. Researchers used to think these chunks were a sign that the Romans weren't mixing up their materials well enough.
Instead, after analyzing concrete samples from Privernum -- an ancient city outside of Rome -- the scientists found that the chunks could fuel the material's "self-healing" abilities. When cracks form, water is able to seep into the concrete, Masic explained. That water activates the leftover pockets of lime, sparking up new chemical reactions that can fill in the damaged sections.
via MIT
Catalysis breakthrough yields self-cleaning wall paint that breaks down air pollutants when exposed to sunlight
Mar 2024, phys.org
The UV radiation creates free charge carriers in the particles, which induce decomposition of the trapped pollutants from air into small parts and their release. In this way, the pollutants are rendered harmless, but do not remain permanently attached to the wall paint. The wall color remains stable in the long term. The new particles work with ordinary sunlight by adding certain additional atoms to the titanium oxide nanoparticles, such as phosphorus, nitrogen, and carbon.
via Vienna University of Technology and Università Politecnica delle Marche: Qaisar Maqbool et al, Highly Stable Self-Cleaning Paints Based on Waste-Valorized PNC-Doped TiO2 Nanoparticles, ACS Catalysis (2024). DOI: 10.1021/acscatal.3c06203
Veins of bacteria could form a self-healing system for concrete infrastructure
Dec 2023, phys.org
Fiber reinforcement has been around since the first masons mixed horsehair into their mud.
BioFiber - polymer fiber encased in a bacteria-laden hydrogel and a protective, damage-responsive shell. The team reports that a grid of BioFibers embedded within a concrete structure can improve its durability, prevent cracks from growing, and enable self-healing.
It uses biomineralizing bacteria, aka microbial-induced calcium carbonate precipitation.
via Drexel University: Mohammad Houshmand Khaneghahi et al, Development of a nature-inspired polymeric fiber (BioFiber) for advanced delivery of self-healing agents into concrete, Construction and Building Materials (2023). DOI: 10.1016/j.conbuildmat.2023.133765
New AI tool discovers realistic 'metamaterials' with unusual properties
Feb 2024, phys.org
They call it "inverse design"
"Tell us what you want to have as properties and we engineer an appropriate material with those properties. What you will then get is not really a material but something in-between a structure and a material, a metamaterial"
via Delft University of Technology Department of Biomechanical Engineering: Helda Pahlavani et al, Deep Learning for Size‐Agnostic Inverse Design of Random‐Network 3D Printed Mechanical Metamaterials, Advanced Materials (2023). DOI: 10.1002/adma.202303481
New all-liquid iron flow battery for grid energy storage
Mar 2024, phys.org
A commonplace chemical used in water treatment facilities has been repurposed for large-scale energy storage in a new battery design for an iron-based flow battery.
It stores energy in a unique liquid chemical formula that combines charged iron with a neutral-pH phosphate-based liquid electrolyte, or energy carrier.
The chemical, 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.
via Pacific Northwest National Laboratory: Phosphonate-based Iron Complex for a Cost-Effective and Long Cycling Aqueous Iron Redox Flow Battery, Nature Communications (2024). DOI: 10.1038/s41467-024-45862-3
Biodegradable aerogel: Airy cellulose from a 3D printer
Apr 2024, phys.org
Using the most common biopolymer on Earth (cellulose), they created a cellulose-based, 3D-printable aerogel, made of nanofibers for viscosity and nanocrystals so that it flows more easily during extrusion. To turn the ink into an aerogel after printing, the researchers replace the pore solvent water first with ethanol and then with air, all while maintaining shape fidelity.
It's an extremely effective heat insulator, and it's biocompatible with living tissues and cells.
It also can be rehydrated and re-dried several times after the initial drying process without losing its shape or porous structure, so it can be stored and transported in dry form and only be soaked in water shortly before use.
via Swiss Federal Laboratories for Materials Science and Technology: Deeptanshu Sivaraman et al, Additive Manufacturing of Nanocellulose Aerogels with Structure‐Oriented Thermal, Mechanical, and Biological Properties, Advanced Science (2024). DOI: 10.1002/advs.202307921
Sunrise to sunset, a new window coating blocks heat, not view
Apr 2024, phys.org
Some window coatings work for a 90-degree angle. Yet at the hottest time of day, the sun's rays enter at oblique angles.
They fabricated a transparent window coating by stacking ultra-thin layers of silica, alumina and titanium oxide on a glass base, with a micrometer-thick silicon polymer added to enhance cooling power. To shuffle the layers into an optimal configuration the team used quantum computing, or more specifically, quantum annealing, and validated their results experimentally.
(Note: We're now using quantum computers to validate experiments, and this is kind of the real story here.)
via University of Notre Dame: Seongmin Kim et al, Wide-angle spectral filter for energy-saving windows designed by quantum annealing-enhanced active learning, Cell Reports Physical Science (2024). DOI: 10.1016/j.xcrp.2024.101847
How buildings influence the microbiome and human health
Apr 2024, phys.org
Modern buildings have a significant influence on human microbial colonization, depending on their nature and degree of shielding from the environment, and that this aspect should be taken into account in future architecture in terms of healthy and microbiome-friendly building conditions.
Buildings interrupt contact with microorganisms from the environment.
Future architecture should restore permeability for microorganisms.
Buildings themselves must be viewed as complex organic systems in the sense of countless interdependent microbial communities, which also have an impact on the human metaorganism.
Taken together, this has negative consequences, for example by creating new niches for disease hosts and vectors in buildings, concentrating waste and toxic substances or reducing ventilation and the entry of sunlight.
According to the researchers, one aim could therefore be to plan and construct the built environment in future in such a way that the focus is not on complete isolation from the natural, microbial environment. On the contrary: buildings can be opened up to nature again and made more nature-friendly.
This can be achieved, for example, by using less toxic building materials and creating an overall greater structural permeability to external, particularly microbial, influences.
via Kiel University Collaborative Research Center 1182 Origin and Function of Metaorganisms and the Canadian Institute for Advanced Research in Toronto, Columbia University, University of Oregon, California Institute of Technology: Thomas C. G. Bosch et al, The potential importance of the built-environment microbiome and its impact on human health, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2313971121
Intelligent liquid: Researchers develop metafluid with programmable response
Apr 2024, phys.org
This came out in April 2024 - How the hell was this not in any other headlines? This is literally the
T-1000
They developed a programmable metafluid with tunable springiness, optical properties, viscosity and can transition between a Newtonian and non-Newtonian fluid.
It's a suspension of small, elastomer spheres between 50 to 500 microns that buckle under pressure, changing the characteristics of the fluid.
A new class of fluid.
With this metafluid, no sensing is needed. The liquid itself responds to different pressures, changing its compliance to adjust the force of the gripper to be able to pick up a heavy bottle, a delicate egg and a small blueberry, with no additional programming.
Also this line:
"We show that we can use this fluid to endow intelligence into a simple robot"
(Because that is exactly what we all want right now.)
via Harvard John A. Paulson School of Engineering and Applied Sciences: Katia Bertoldi, Shell buckling for programmable metafluids, Nature (2024). DOI: 10.1038/s41586-024-07163-z.
