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Bacteria Used To Fix Cracked Concrete
An anonymous reader writes "Researchers at the UK's University of Newcastle have created a new type of bacteria that generates glue to hold together cracks in concrete structures — that means everything from concrete sidewalks to buildings that have been damaged by earthquakes. When the cells have been germinated, they burrow deep into the concrete until they reach the bottom. At this point, the concrete repair process is activated, and the cells split into three types that produce calcium carbonate crystals, act as reinforcing fibers, and produce glue which acts as a binding agent to fill concrete gaps."
Gigacrete looks like a better material for building in my opinion. I'll just have bacteria in my yogurt for now.
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He who knows best knows how little he knows. - Thomas Jefferson
RTFA, it's not very long and explains just that fact you need; it does know when to stop.
This is the NSA, we're gonna geet U h@x0r5! Also, what is a h@x0r5?
The spores germinate only in very alkaline environments — concrete has a quite high pH. The article is vague on details, but notes that "[the bacteria] have a built-in self-destruct gene that prevents them from proliferating away from the concrete target."
Now, What Could Possibly Go Wrong and all of that, but the bases are nominally covered.
An older article with considerably more detail. Not sure if it's the same bacteria.
http://www.newscientist.com/article/dn19386-for-selfhealing-concrete-just-ad
What's the acidity of your lungs? Oh, I see. You didn't read the article. Carry on, then.
The problem, with bullet wound is... they are not always clean, you can have some clothes debris, or other dirt. Closing the wound is easy (well, relatively speaking) but cleaning it well enough is another thing.
Several hundred years? Try several thousand.
The bacteria they made in the lab likes the acidity of concrete. What about the mutant bacteria that the bacteria in the crack makes?
It won't survive because it's still in the very alkaline concrete environment? Or as Morbo might put it: EVOLUTION DOES NOT WORK THAT WAY.
This engineered bacterium system was entered into the International Genetically Engineered Machine competition, so there's a lot more information about this project at the team's project page. In particular, there's a more thorough description of the kill switch the team engineered to prevent the spread of this bacterium beyond the target environment, the underlying mechanism being that sucrose must be available in the environment to prevent the bacterium from producing a toxin which kills itself.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
The main problem with a bullet wound is that it used to be a normal functioning part of the body and not a bullet wound...
Also, the concrete repair activity is produced by upregulation of genes natural to Bacillus subtilis, not by anything transgenic. The upregulation of these genes presents an energy cost to the engineered bacterium while providing no benefit- if these bacteria mutate, it is more likely to be towards the wild phenotype. In addition, the team responsible has added a kill switch which tells the bacteria to commit suicide if sucrose is not present.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
Right, and battery acid is really good at curing the common cold.
I dunno where you're getting this info, but no, bullets certainly do not "sterilize" anything. One of the leading causes of death historically has been infection. We're better at dealing with it today, but infections still occur on a regular basis:
"A gunshot is never sutured closed as the infection rate is very high. Bullets drag clothing into the wound and along the bullet track. Since clothing is of course not sterile, the wound is prone to infection if closed. Open wounds almost never get infected."
http://www.tacticalmedicalpacks.com/files/Combat_Tactics_Trauma_article.pdf
"We have presented a series of 120 consecutive operative cases of penetrating wounds of the abdomen-72 gunshot wounds and 48 stab wounds. The majority of patients were in the 18 to 40 age group. The infection rate was 22% for gunshot wounds and 4.8% for knife wounds."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2609419/pdf/jnma00480-0069.pdf
There are three principal parts to the filler produced by these bacteria. First, the bacterium naturally produces calcium carbonate as a byproduct of breaking down urea as a nitrogen source; this activity has been greatly increased in the engineered bacterium. The second part is a "glue" made from levan, a polysaccharide that the bacterium is able to produce from sucrose; this activity is also natural, but highly upregulated in the engineered bacterium. The final part is the bacterial cells themselves; the cells are made long and threadlike by expressing a protein that halts cell division, and these filamentous cells act as reinforcing fibers. In practical usage, a solution of nutrients (including sucrose in particular) would need to be sprayed along with the bacterial spores in order for them to display this concrete-filling activity. This information comes from here.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
If you've ever tried to pump glue into a crack in concrete, you'll quickly figure that out. It's somewhere between messy and inadequate as a repair method, and certainly doesn't get into the smaller cracks, let alone the microcracks. The idea here is to have the glue self-extend, filling the air pockets and microcracks that no glue with sufficient surface tension to stick could ever manage.
However I think where this will become a more useful technique is for fixing the kinds of surface cracks that ail structures exposed to repeated wet/freeze/thaw cycles -- the typical winter climate for the east slope of the Rocky Mountains. Mount Rushmore would seem to be a good candidate, since seasonal surface cracking is what's causing damage.
Concrete roads that suffer similar winter freeze/thaw damage could also benefit -- instead of trying to patch the road one crack at a time (usually an exercise in futility, culminating in yawning potholes), or having to dig up and replace the concrete (an extremely expensive job), just wash it with a slurry of this bacteria. That could even eliminate most of the seasonal damage, by filling the microcracks that are where freeze damage starts.
Imagine if your state and local highway departments could reduce their budgets by simply needing to do less repair on concrete-based roads. Even if you don't believe in reducing taxes when need is reduced, it would free up that budget to use elsewhere.
~REZ~ #43301. Who'd fake being me anyway?
The Romans invented concrete.
That's only 1600-2200 or so years ago.
The Romans started using concrete before 200 B.C., but Wikipedia says the Egyptian pyramids were built with concrete long before that. So that makes its invention 2200-4600 years ago.
IMO "several hundred" was correct.
From your link: "being more than two but fewer than many". Considering civilization has only been around for ~60 centuries, "several" is arguably less than twenty. Try "many hundreds" next time you go for your pedantic medal. Thanks for playing.
That depends. How many highly alkali environments are there in nature? (Answer: Very few)
Solids do not have pH. You can't have a pH without a solvent. The alkali environment present in concrete does not exist within humans...or any animal or plant I'm aware of.
Evolution doesn't work that way. There has to be selection pressure. Bacteria that live in concrete but thrive in a lower pH would be selected against - the "thrive in high pH" would outcompete them.
You can't make this assessment without knowing the pH of the pH range of the bacteria, the pH range of the concrete, and knowing how common that pH range is in nature.
The problem, with bullet wound is...[dirt].
Another problem with bullet wounds is emergency room doctors who believe the myth of "hydrostatic shock" damage and chop out a core of tissue around the bullet's path (as if it were a linear cancer), rather than treating it properly by cleaning and closing the wound (as if it were any other puncture-and-displacement trauma).
Yo, Docs! Even if the bullet somehow WAS traveling faster than the speed of sound in flesh (like about mach 4.4) shock waves aren't any big deal for soft tissue. Think Lithotripter.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way