Jan 27, 2021 10:13 PM
(This post was last modified: Jan 28, 2021 08:09 PM by C C.)
Chemists settle battery debate, propel research forward
https://www.newswise.com/doescience/?art...GVzL2xpc3Q=
BLURB: Researchers used ultrabright x-rays to identify lithium hydride and a new form of lithium fluoride in the interphase of lithium metal anodes...
Topology 101: the hole truth
https://www.quantamagazine.org/topology-...-20210126/
EXCERPT: In everyday language, we use “hole” in a variety of nonequivalent ways. One is as a cavity, like a pit dug in the ground. Another is as an opening or aperture in an object, like a tunnel through a mountain or the punches in three-ring binder paper. Yet another is as a completely enclosed space, such as an air pocket in Swiss cheese. A topologist would say that all but the first example are holes. But to understand why – and why mathematicians even care about holes in the first place — we have to travel through the history of topology, starting with how it differs from its close kin, geometry.
In geometry, shapes like circles and polyhedra are rigid objects; the tools of the trade are lengths, angles and areas. But in topology, shapes are flexible things, as if made from rubber. A topologist is free to stretch and twist a shape. Even cutting and gluing are allowed, as long as the cut is precisely reglued. A sphere and a cube are distinct geometric objects, but to a topologist, they’re indistinguishable. If you want a mathematical justification that a T-shirt and a pair of pants are different, you should turn to a topologist, not a geometer. The explanation: They have different numbers of holes. Leonhard Euler kicked off the topological investigation of shapes in the 18th century... (MORE - details)
Recycling plastic doesn't reduce waste much. Chemists are trying to change that
https://www.sciencenews.org/article/chem...-materials
EXCERPTS: The difficulties of recycling plastic into anything manufacturers want to use is a big reason why the world is littered with so much plastic waste, says Eric Beckman, a chemical engineer at the University of Pittsburgh [...] The amount of plastic recycled in the United States has increased over the last few decades — but those levels still pale in comparison with the amount of plastic that goes into landfills.
[...] With plastic collecting everywhere from the top of Mount Everest to the bottom of the Mariana Trench, there’s an urgent need to reduce the amount of plastic that gets thrown away. Some people propose replacing plastics with biodegradable materials, but those replacements are generally not as strong or cheap to make as plastics. Since, realistically, plastic is not going away any time soon, chemists who understand the ins and outs of all this pesky plastic are working to make it easier to recycle and turn into higher-quality material that’s useful for more things.
[...] Good as new. Even if every piece of plastic trash could easily be recycled, that still wouldn’t solve the world’s plastic problem. There are a couple major issues with how recycling currently works that severely limit the usability of recycled materials.
For one thing, recycled plastics inherit all the dyes, flame retardants and other additives that gave each original plastic piece its distinctive look and feel. “The plastic that you actually recover at the end of all this is really a very complex mixture,” says chemist Susannah Scott of the University of California, Santa Barbara. Few manufacturers can use plastic with a random mishmash of properties to make something new.
Plus, recycling breaks some of the chemical bonds in plastic molecules, affecting the strength and consistency of the material. ... That limits the number of times plastic can be recycled before it has to be landfilled.
The solution to both problems could lie in a new kind of recycling process, called chemical recycling, which promises to make pure new plastic an infinite number of times. Chemical recycling involves taking plastics apart on the molecular level...
[...] Microbial help. An enzyme naturally produced by microbes broke down about 50 percent of polyethylene terephthalate, or PET (blue line). A tweaked version of the enzyme broke down more than 80 percent of the plastic (black dotted line). Increasing the amount of the enzyme from 1 milligram per gram of PET to 3 milligrams made it even more efficient — breaking down about 90 percent of PET...
[...] Milder conditions. But other plastics, like polyethylene and polypropylene, are much harder to break down via chemical recycling. ... Scott, the UC Santa Barbara chemist, proposes partially breaking down these sturdy plastics in a more controlled way, under milder conditions, to make other kinds of useful molecules...
[...] Built to last. The plastics produced today were never designed to be used more than once. That’s why recycling plastics — particularly into material that is as good as new — is so difficult. But researchers are going back to the drawing board to ask themselves, “What does the next generation of materials look like? How do you design a material specifically so that it never has to go into a landfill?” says Eric Beckman, a chemical engineer at the University of Pittsburgh. “Chemists are looking at whether you can design a polymer that falls apart on command...” (MORE - details)
https://www.newswise.com/doescience/?art...GVzL2xpc3Q=
BLURB: Researchers used ultrabright x-rays to identify lithium hydride and a new form of lithium fluoride in the interphase of lithium metal anodes...
Topology 101: the hole truth
https://www.quantamagazine.org/topology-...-20210126/
EXCERPT: In everyday language, we use “hole” in a variety of nonequivalent ways. One is as a cavity, like a pit dug in the ground. Another is as an opening or aperture in an object, like a tunnel through a mountain or the punches in three-ring binder paper. Yet another is as a completely enclosed space, such as an air pocket in Swiss cheese. A topologist would say that all but the first example are holes. But to understand why – and why mathematicians even care about holes in the first place — we have to travel through the history of topology, starting with how it differs from its close kin, geometry.
In geometry, shapes like circles and polyhedra are rigid objects; the tools of the trade are lengths, angles and areas. But in topology, shapes are flexible things, as if made from rubber. A topologist is free to stretch and twist a shape. Even cutting and gluing are allowed, as long as the cut is precisely reglued. A sphere and a cube are distinct geometric objects, but to a topologist, they’re indistinguishable. If you want a mathematical justification that a T-shirt and a pair of pants are different, you should turn to a topologist, not a geometer. The explanation: They have different numbers of holes. Leonhard Euler kicked off the topological investigation of shapes in the 18th century... (MORE - details)
Recycling plastic doesn't reduce waste much. Chemists are trying to change that
https://www.sciencenews.org/article/chem...-materials
EXCERPTS: The difficulties of recycling plastic into anything manufacturers want to use is a big reason why the world is littered with so much plastic waste, says Eric Beckman, a chemical engineer at the University of Pittsburgh [...] The amount of plastic recycled in the United States has increased over the last few decades — but those levels still pale in comparison with the amount of plastic that goes into landfills.
[...] With plastic collecting everywhere from the top of Mount Everest to the bottom of the Mariana Trench, there’s an urgent need to reduce the amount of plastic that gets thrown away. Some people propose replacing plastics with biodegradable materials, but those replacements are generally not as strong or cheap to make as plastics. Since, realistically, plastic is not going away any time soon, chemists who understand the ins and outs of all this pesky plastic are working to make it easier to recycle and turn into higher-quality material that’s useful for more things.
[...] Good as new. Even if every piece of plastic trash could easily be recycled, that still wouldn’t solve the world’s plastic problem. There are a couple major issues with how recycling currently works that severely limit the usability of recycled materials.
For one thing, recycled plastics inherit all the dyes, flame retardants and other additives that gave each original plastic piece its distinctive look and feel. “The plastic that you actually recover at the end of all this is really a very complex mixture,” says chemist Susannah Scott of the University of California, Santa Barbara. Few manufacturers can use plastic with a random mishmash of properties to make something new.
Plus, recycling breaks some of the chemical bonds in plastic molecules, affecting the strength and consistency of the material. ... That limits the number of times plastic can be recycled before it has to be landfilled.
The solution to both problems could lie in a new kind of recycling process, called chemical recycling, which promises to make pure new plastic an infinite number of times. Chemical recycling involves taking plastics apart on the molecular level...
[...] Microbial help. An enzyme naturally produced by microbes broke down about 50 percent of polyethylene terephthalate, or PET (blue line). A tweaked version of the enzyme broke down more than 80 percent of the plastic (black dotted line). Increasing the amount of the enzyme from 1 milligram per gram of PET to 3 milligrams made it even more efficient — breaking down about 90 percent of PET...
[...] Milder conditions. But other plastics, like polyethylene and polypropylene, are much harder to break down via chemical recycling. ... Scott, the UC Santa Barbara chemist, proposes partially breaking down these sturdy plastics in a more controlled way, under milder conditions, to make other kinds of useful molecules...
[...] Built to last. The plastics produced today were never designed to be used more than once. That’s why recycling plastics — particularly into material that is as good as new — is so difficult. But researchers are going back to the drawing board to ask themselves, “What does the next generation of materials look like? How do you design a material specifically so that it never has to go into a landfill?” says Eric Beckman, a chemical engineer at the University of Pittsburgh. “Chemists are looking at whether you can design a polymer that falls apart on command...” (MORE - details)