Rethinking the incandescent lightbulb
Apr 2023, phys.org
Instead of tossing out incandescent bulbs, they have made them more efficient using a two-layer filament of carbon nanotube and a nitrogen-boron ceramic, and rather than placing it in a glass bulb they put it in a box with a window made of a type of quartz that allows for recycling photons.
They call the result a photon-recycling incandescent lighting device, with energy efficiency nearly equal to an LED bulb, a much longer lifetime and color fidelity nearly on a par with traditional incandescent bulbs.
via School of Materials Science and Engineering State Key Laboratory of Metal Matrix Composites at Center for Hydrogen Science, and Zhiyuan Innovative Research Center of Shanghai Jiao Tong University, Shanghai HeiYi Materials Technology Co. Ltd., Shanghai IdeaOptics Co. Ltd., Tianjin H-Chip Technology Group Corporation: Heng Zhang et al, A photon-recycling incandescent lighting device, Science Advances (2023). DOI: 10.1126/sciadv.adf3737
Termite mounds reveal secret to creating 'living and breathing' buildings that use less energy
May 2023, phys.org
I'm not getting what's so special -- I do remember hearing about termite mounds 15 years ago at the biomometic architecture lectures. Maybe it's because they got better at modeling. Also this: "We imagine that building walls in the future, made with emerging technologies like powder bed printers, will contain networks similar to the egress complex. These will make it possible to move air around, through embedded sensors and actuators that require only tiny amounts of energy," said Andréen.
via bioDigital Matter research group of Lund University, School of Architecture, Design and the Built Environment at Nottingham Trent University: Termite-inspired metsamaterials for flow-active building envelopes, Frontiers in Materials (2023). DOI: 10.3389/fmats.2023.1126974.
Saudi Arabia's 'The Line' isn't a revolution in urban living, say researchers
Jun 2023, phys.org
(No shit)
Something about the base design parameter of the human body and human mobility:
The Line is planned to be a city built from nothing in the desert. It is to consist of two gigantic, unbroken rows of skyscrapers, with living space in between. It is planned to be 170 kilometers long, 200 meters wide and 500 meters high, higher than any building in Europe, Africa, and Latin America, stretching straight ahead from the Red Sea to the east.
Nine million people are expected to live in it—more than in any other city in Saudi Arabia. This translates into a population density of 265,000 people per square kilometer—ten times denser than Manhattan and four times denser than the inner districts of Manila, currently estimated to be the densest urban neighborhoods on Earth.
"A line is the least efficient possible shape of a city," says Prieto-Curiel. "There's a reason why humanity has 50,000 cities, and all of them are somehow round," he emphasizes.
Assuming a walking distance of one kilometer, only 1.2% of the population is within walking distance from each other. This hinders active mobility, so people will depend on public transport.
The backbone of public transportation is planned to be a high-speed rail system. "For everyone to be within walking distance of a station, there must be at least 86 stations," explains CSH researcher Dániel Kondor. As a result, trains spend considerable time in stations and will not be able to reach high travel speeds between any two stations.
According to the researchers, a trip, therefore, is expected to take 60 minutes on average, and at least 47% of the population would have an even longer commute. Even with additional express lines, gains are limited due to the additional transfers necessary. The result is that people would still be traveling longer than in other major cities, such as Seoul, where 25 million people commute for less than 50 minutes.
Good point to remember: While planned cities often did not live up to expectations; thus, there is a need for more public engagement about urban design on a human scale.
Another point to remmeber?
Mazdar still doesn't really exist.
via Complexity Science Hub Vienna: Rafael Prieto-Curiel et al, Arguments for building The Circle and not The Line in Saudi Arabia, npj Urban Sustainability (2023). DOI: 10.1038/s42949-023-00115-y
Want better kimchi? Make it like the ancients did
Apr 2023, phys.org
The porous structure of these earthenware vessels mimics the loose soil where lactic acid bacteria—known for their healthy probiotic nature—are found. While previous studies have shown that kimchi fermented in onggi has more lactic acid bacteria, no one knew exactly how the phenomenon is connected to the unique material properties of the container.
They concluded that the onggi's porous walls permitted the carbon dioxide to escape the container, which accelerated the speed of fermentation. The onggi's porosity also functioned as a "safety valve," resulting in a slower increase in carbon dioxide levels than the glass jar while blocking the entry of external particles. Their data revealed that the carbon dioxide level in onggi was less than half of that in glass containers.
They also found that the beneficial bacteria in the onggi-made kimchi proliferated 26% more than in the glass counterpart. In the glass jar, the lactic acid bacteria became suffocated by their own carbon dioxide in the closed glass container. It turns out that because the onggi releases carbon dioxide in small rates, the lactic acid bacteria are happier and reproduce more.
"Onggi were designed without modern knowledge of chemistry, microbiology, or fluid mechanics, but they work remarkably well"
There's a pretty in-depth video about Onggi pottery where traditional artisans and university scientists get together to analyze the properties of clay vessels made in four different permutations, and they find that handmade pots or wood-fired kilns (but not poured-mold pots or gas-fired kilns) make holes in the clay too small for water to enter, but large enough for air to leave. They remind us these properties are like the high-tech modern day Gore-Tex, yet Korean potters have known how to do it for millenia.
via Georgia Institute of Technology: Soohwan Kim et al, Onggi's permeability to carbon dioxide accelerates kimchi fermentation, Journal of The Royal Society Interface (2023). DOI: 10.1098/rsif.2023.0034
Secret ingredient in durable Maya plaster discovered
Apr 2023, phys.org
Just building things (and a recipe for building in the coming age of the subtropical rainforest jungle planet)
The typical process for creating plaster involves calcination (baking) of carbonate rock material, such as limestone, and then mixing in water while allowing the material to react with carbon dioxide in the air. The result is known commonly as lime mortar. The team followed this formula but also mixed in sap and then used it as a plaster. Testing showed that it had the same properties as the ancient Maya plaster, which included water solubility, making it impervious to the extreme Honduran humidity.
via University of Granada: Carlos Rodriguez-Navarro et al, Unveiling the secret of ancient Maya masons: Biomimetic lime plasters with plant extracts, Science Advances (2023). DOI: 10.1126/sciadv.adf6138
Clever coating turns lampshades into indoor air purifiers
Aug 2023, phys.org
Plot Twist!
(Now we need to go back to using incandescent bulbs to make use of their waste heat!)
The room is filled with acetylene gas, then an aluminum lampshade coated with a thermocatalysts made of titanium dioxide and a small amount of platinum (or less expensive iron- or copper-based catalysts), heated to 250F by a 100-watt halogen light bulb, to eventually turn the acetylene gas into acetic acid, then formic acid, and then carbon dioxide and water.
via Yonsei University in Korea: Thermocatalytic oxidation of VOC through harnessing indoor waste heat, American Chemical Society Fall 2023.
Material would allow users to 'tune' windows to block targeted wavelengths of light
Sep 2023, phys.org
The key to more dynamic window materials is water.
Specifically, the researchers found that --
When water is bound within the crystalline structure of a tungsten oxide to form tungsten oxide hydrate, the material exhibits a previously unknown behavior where (if lithium ions and electrons are injected into the hydrate material) it first transitions into a "heat blocking" phase, allowing visible wavelengths of light to pass through, but blocking infrared light; but if even more lithium ions and electrons are injected, the material then transitions into a dark phase, blocking both visible and infrared wavelengths of light.
"The presence of water in the crystalline structure makes the structure less dense, so the structure is more resistant to deformation when lithium ions and electrons are injected into the material," says Jenelle Fortunato, first author of the paper and a postdoctoral fellow at NC State.
via Materials Science and Engineering at North Carolina State University and University of Texas at Austin: Jenelle Fortunato et al, Dual-Band Electrochromism in Hydrous Tungsten Oxide, ACS Photonics (2023). DOI: 10.1021/acsphotonics.3c00921
Pottery becomes water treatment device for Navajo nation
Oct 2023, phys.org
Awesome in every way:
The team has developed a new water filtration solution for members of the Navajo Nation, lining clay pots with pine tree resin collected from the Navajo Nation and incorporating tiny, silver-based particles that can be used to purify water to make it drinkable.
They worked closely with a third-generation potter from Arizona—Deanna Tso, who is also a co-author on the paper—to create a device that is simple for the users. All they have to do is pour water through the clay pots, and the coated pottery removes bacteria from water and generates clean, drinkable water.
The Navajo Nation has a history of mistrust of outsiders, the researchers say, and that makes it less likely that people there would adopt a new technology made entirely by others. Using pottery, working with the community, and relying on local materials were important to the effectiveness of this project.
"Navajo pottery is at the heart of this innovation because we hoped it would bridge a trust gap," said Lewis Stetson Rowles III, now a faculty member at Georgia Southern University's Department of Civil Engineering and Construction after earning a Ph.D. from UT in 2021. "Pottery is sacred there, and using their materials and their techniques could help them get more comfortable with embracing new solutions."
The materials and construction process for the pots cost less than $10, making for a potentially low-cost solution.
"This is just the beginning of trying to solve a local problem for a specific group of people," Saleh said. "But the technical breakthrough we've made can be used all over the world to help other communities."
via University of Texas at Austin Department of Civil, Architectural and Environmental Engineering: Lewis S. Rowles et al, Integrating Navajo Pottery Techniques To Improve Silver Nanoparticle-Enabled Ceramic Water Filters for Disinfection, Environmental Science & Technology (2023). DOI: 10.1021/acs.est.3c03462
