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1. The cited system does not include a light-harvesting component. It merely postulates that the required energy could be generated from photovoltaics. This would introduce additional cost and complexity along with an efficiency hit.
2. The cited system comprises a bacterium in conjuction with an electrode-supported catalyst, whereas the system under discussion is solely an engineered bacterium.
Finally, it is not correct to refer to cadmium and cysteine as feedstocks. They are components of the catalyst, and they are not consumed during catalysis. The only feedstocks for both systems are CO2 and water.
Not really. Using CO2 to generate a fuel which then liberates CO2 when it is consumed ends up being CO2-neutral, which is exactly the way to go.
Taking a step back, in 2016, this group did cover a bacterium with tiny semiconductor nanoparticles (specifically CdS) just as you say. That work is described here: http://www.pnas.org/content/113/42/11750.full In short, the semiconductors act as mini-solar cells, converting light into electrical current. The bacteria then use that electricity to convert CO2 into acetic acid. That already is pretty cool.
However, what they claim now is that they don't even need to make the semiconductor nanoparticles. They can simply grow the bacteria in an environment containing cadmium and sulfur sources and the bacterium will synthesize it's own cadmium sulfide coat, and use it for photosensitization.
This is really pretty wild. Bacteria will often incorporate various elements from their host medium, but the generally use them to make biomolecules, not semiconductors. Right now, this is just being presented at a conference, but it will be very interesting to see the details when the full paper comes out.
In 1973, the artist Richard Serra made a film called Television Delivers People which declares "You are the product of TV" [0]
Key to Noam Chomsky's _Manufacturing Consent_ (1988) is the idea that advertising-supported media caters to the desires of the advertiser, not the media consumer [1]
[0]: https://en.wikipedia.org/wiki/Television_Delivers_People [1]: https://en.wikipedia.org/wiki/Manufacturing_Consent
See also: http://www.chilton-computing.org.uk/ccd/graphics/p012.htm
1. The overall idea here is to take an intermittent energy source (e.g. solar power) and "store" it as chemical fuel, in this case hydrogen and oxygen. This is what plants do, and we can also view fossil fuels as resulting from the "storage" of millions of years of solar energy. Note also that you get the water back when you burn the hydrogen, so there is no net consumption of water, it's just a carrier.
2. While you can split water without a catalyst, most of the energy gets wasted as heat, so this is not a great way to go if you're trying to do energy storage.
3. Efficient catalysts exist for this reaction, but they are based on rare and expensive metals, typically Pd, Pt, and Ir. As a result, there has been a search for catalysts involving "first-row" metals such as Fe, Co, Ni, etc.
4. There are variety of metrics for an electrocatalyst (efficiency, stability, cost, etc), but it's a fair bet that if this were significantly better than state-of-the-art, it would be in Science or Nature rather than PNAS.
On the other hand, the key difficulty in synthetic chemistry, and the one that occupies the majority of a chemist's time is the identification of the correct reagent(s), the correct solvent, and the correct time, temperature, and concentration such that the desired reaction proceeds in a convenient amount of time and with the correct chemo- and regio-selectivity, that the reaction conditions are tolerated by the rest of the molecule, and that the product can be easily isolated from the reaction byproducts.
In my opinion, as long as these problems remain, then being able to turn retrosynthetic analysis over to a machine appears to me to provide little benefit.
The essay is long but well worth reading: https://www.its.caltech.edu/~dg/crunch_art.html
This is incorrect. In both track-and-field and cycling there are extensive out-of-competition tests, the purpose of which is exactly that. This is because performance-enhancing drugs are often more beneficial in training than in competition.
http://www.faqs.org/sports-science/Mo-Pl/Out-of-Competition-...
You mean like reading HN?
Remember that the British experience with tea dates back only to the 17th century, whereas the Chinese and Japanese have had much longer to refine the growing, processing, and drinking of tea.
0) There is a problem that needs to be fixed.
1) Boss recommends A
2) Engineer knows A won't work, but they try it anyway
3) A doesn't work, so they stay up late implementing B. (Of course, they wouldn't have had to stay up late had they just been allowed to implement B first...)
4) B works
5) Boss takes the credit
6) After years of making the boss look good, engineer gets promoted
[0] http://nomads.ncep.noaa.gov/cgi-bin/filter_hiresconus.pl