Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Growing metallic wood to new heights + Experimental African houses outsmart malaria

#1
C C Offline
(architecture) The experimental African houses that outsmart malaria
https://www.wired.com/story/the-experime...t-malaria/

EXCERPT: . . . The professor had figured out that the way to avoid getting bitten wasn’t just nets; it was architecture. He had filled in the holes in his home’s eaves. “We asked him: ‘Why do you do that?’” recalls Lindsay.

“So I get fewer mosquitoes coming in,” he replied.

[...] So starting in 2017, Lindsay’s team began building small experimental huts to test which designs would keep mosquitoes out and let people remain cool and comfortable. Their tweaks, which ranged from adding small screened windows to raising the homes on stilts, made a huge difference. Some configurations dropped mosquito visits by up to 95 percent. Lindsay’s team published the results in two reports of the Journal of the Royal Society Interface in May.

The results are encouraging to experts who say that improved housing can save children from malaria...

[...] What Lindsay’s team found is that mosquito-proofing doesn’t have to mean creating an impenetrable fortress, but can rather be about letting exhaled breath out. Ventilation foils the hungry mosquitoes, because it prevents CO2 from building up overnight. Physicists with the team modeled the fluid dynamics of carbon dioxide in these homes, confirming how airflow breaks up the stagnant clouds that attract mosquitoes. Adding more screened space dropped CO2 levels by up to 36 percent.

“It almost becomes what would be a stealth house,” Lindsay says. “You're hiding the house and the occupants from mosquitoes."

The windows also played another role: They made the houses about 1 degree cooler. “This is a real win-win,” Lindsay says. “Because it's not just about reducing malaria, it’s about getting a good night's sleep.” (MORE - details)


(engineering, design) Growing 'metallic wood' to new heights
https://blog.seas.upenn.edu/growing-meta...w-heights/

RELEASE: Natural wood remains a ubiquitous building material because of its high strength-to-density ratio; trees are strong enough to grow hundreds of feet tall but remain light enough to float down a river after being logged.

For the past three years, engineers at the University of Pennsylvania’s School of Engineering and Applied Science have been developing a type of material they’ve dubbed “metallic wood.” Their material gets its useful properties and name from a key structural feature of its natural counterpart: porosity. As a lattice of nanoscale nickel struts, metallic wood is full of regularly spaced cell-sized pores that radically decrease its density without sacrificing the material’s strength.

The precise spacing of these gaps not only gives metallic wood the strength of titanium at a fraction of the weight, but unique optical properties. Because the spaces between gaps are the same size as the wavelengths of visible light, the light reflecting off of metallic wood interferes to enhance specific colors. The enhanced color changes are based on the angle that light reflects off of the surface, giving it a dazzling appearance and the potential to be used as a sensor.

Penn Engineers have now solved a major problem preventing metallic wood from being manufactured at meaningful sizes: eliminating the inverted cracks that form as the material is grown from millions of nanoscale particles to metal films big enough to build with. Preventing these defects, which have plagued similar materials for decades, allows strips of metallic wood to be assembled in areas 20,000 times greater than they were before.

James Pikul, assistant professor in the Department of Mechanical Engineering and Applied Mechanics, and Zhimin Jiang, a graduate student in his lab, have published a study demonstrating this improvement in the journal Nature Materials.

When a crack forms within an everyday material, bonds between its atoms break, eventually cleaving the material apart. An inverted crack, by contrast, is an excess of atoms; in the case of metallic wood, inverted cracks consist of extra nickel that fills in the nanopores critical to its unique properties. “Inverted cracks have been a problem since the first synthesis of similar materials in the late 1990s,” says Jiang. “Figuring out a simple way of eliminating them has been a long-standing hurdle in the field.”

These inverted cracks stem from the way that metallic wood is made. It starts as a template of nanoscale spheres, stacked on top of one another. When nickel is deposited through the template, it forms metallic wood’s lattice structure around the spheres, which can then be dissolved away to leave its signature pores.

However, if there are any places where the spheres’ regular stacking pattern is disrupted, the nickel will fill those gaps, producing an inverted crack when the template is removed.

Nanoscale pores are the key to metallic wood’s properties, but if there is a crack in the template before nickel is added, it will become an “inverted crack” — a seam of solid nickel — when the template is removed. The researchers’ technique allows for crack-free regions that are 20,000 times larger than previously possible.

“The standard way to build these materials is to start with a nanoparticle solution and evaporate the water until the particles are dry and regularly stacked. The challenge is that the surface forces of water are so strong that they rip the particles apart and form cracks, just like cracks that form in drying sand,” Pikul says. “These cracks are very difficult to prevent in the structures we are trying to build, so we developed a new strategy that allows us to self-assemble the particles while keeping the template wet. This prevents the films from cracking, but because the particles are wet, we have to lock them in place using electrostatic forces so that we can fill them with metal.”

With larger, more consistent strips of metallic wood now possible, the researchers are particularly interested in using these materials to build better devices.

“Our new manufacturing approach allows us to make porous metals that are three times stronger than previous porous metals at similar relative density and 1,000 times larger than other nanolattices,” Pikul says. “We plan to use these materials to make a number of previously impossible devices, which we are already using as membranes to separate biomaterials in cancer diagnostics, protective coatings and flexible sensors.”

This work was partially funded by the pilot grant program from the Center for Innovation & Precision Dentistry at the University of Pennsylvania and by the National Science Foundation under CAREER Grant No. 1943243.


https://www.youtube-nocookie.com/embed/suQp350opGw
Reply


Possibly Related Threads…
Thread Author Replies Views Last Post
  Unique homes/cabins/cottages/tiny houses Magical Realist 68 1,698 Jul 22, 2023 11:46 PM
Last Post: Magical Realist
  Wood ash cement & fired brick hut (primitive architecture) + New aquaculture designs C C 0 89 May 7, 2022 05:57 PM
Last Post: C C
  Transparent wood could be architecture's windows of tomorrow C C 0 136 Oct 8, 2020 09:17 PM
Last Post: C C
  Can wood construction transform cities from carbon source to carbon vault? C C 0 152 Jan 30, 2020 08:58 PM
Last Post: C C
  Experimental device generates electricity from coldness of universe (new designs) C C 0 483 May 7, 2019 06:22 PM
Last Post: C C
  How a $10 Billion Experimental City Nearly Got Built in Rural Minnesota C C 4 515 Apr 6, 2018 04:44 PM
Last Post: Magical Realist
  The Case for Making Cities Out of Wood C C 0 318 Feb 19, 2018 04:04 AM
Last Post: C C
  Pop up houses Magical Realist 0 303 Jul 18, 2017 06:44 PM
Last Post: Magical Realist
  World's tallest wood building completed: 18 storeys C C 1 531 Oct 5, 2016 06:36 PM
Last Post: Yazata
  10 ingenious elevated designs + Bamboo replacing wood + Bergamo sofa: design find C C 0 442 Sep 16, 2016 06:56 PM
Last Post: C C



Users browsing this thread: 1 Guest(s)