Jinzou Ningen – Artificial Human project

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Exploring possibilities

There Is No Nuclear Waste Problem

An issue which has been raised so often that it has become synonymous with nuclear power is that of nuclear waste and the storage of it. Through decades of clamoring by anti-nuclear groups and individuals there is no doubt in the mind of the average person that the issue of many tons of highly dangerous, highly radioactive nuclear waste is both real and the primary reason to switch to so-called renewable technologies such as solar and wind power. Due to the strong anti-nuclear lobby and public mood also due to the nuclear threat of the Cold War precious little effort has been made to examine in how far this nuclear waste issue is real or imaginary.

The premise of the suggested nuclear waste issue is that nuclear reactors will always produce large amounts of highly-radioactive materials which will have to be stored for thousands of years, forming a lethal risk to current and future generations. Hereby we have a few items of importance: that nuclear reactors produce large amounts of highly-radioactive material, that this will have to be stored as waste, and that this forms a major risk to humanity.

Starting with the first item, less than a minute of research will show that current commercial reactors use only about 0.65% of the energy contained in the uranium as it is mined, and less than 5% of the enriched uranium fuel.[1] The major alternative reactor design, so-called breeder reactors [2] which due its neutron economy are capable of generating more fissile material (fuel) than it consumes. This includes the actinides, the transuranic elements which are highly radioactive due to their unstable nature. A breeder reactor in combination with a reprocessing step for removing neutron-absorbing fission products (low-radioactive elements) can use virtually all of the energy contained in the uranium fuel, reducing the fuel requirements by about two orders of magnitude (90+% versus <5% efficiency).

With a breeder reactor design such as the Integral Fast Reactor [3] (cancelled in 1994 by the US Congress despite working as expected) or its successors Sodium-Cooled Fast Reactor (SFR) [4] and S-PRISM [5], so-called Generation IV reactors, the only waste would be long-lived fission products (LLFP) [6], which have half-lives on the order of 200,000 to millions of years and sometimes have such low radioactivity that these elements can still be found in nature dating back to the formation of the universe. Only seven of these are relevant due to having relatively short half-lives:

  • Technetium-99
  • Tin-126
  • Selenium-79
  • Zirconium-93
  • Caesium-135
  • Palladium-107
  • Iodine-129

None of these seven isotopes form a risk to biological life. Technetium-99 [7] as the most short-lived of these is commonly injected into humans in the form of Tc-99m, an isomeric form of Tc-99, for medical testing where it transitions back into the Tc-99 form inside the human body and is deemed virtually harmless due to the half-life of 211,000 years.

If we start building Generation IV reactors such as the ones listed above now, we can use existing ‘waste’ from Gen-II and III reactors in them, while adding small amounts of fresh uranium fuel from time to time. In combination with uranium mining from seawater we would have virtually infinite amounts of energy, with no dangerous waste to store. This takes care of the second point, and the third point.

When talking about radiation hazards, one would be wise to consider natural sources of radiation, such as granite [8]. Many types of granite contain significant amounts of uranium and thorium, which decay into radioactive radon gas, which is the number two cause of lung cancer in the USA after smoking. A building with for example a basement on granite bedrock is likely to collect this gas, resulting in significant cancer risk for its inhabitants. While deemed harmless by most, granite and other types of rock apparently are a far great radiation risk than that imagined for the waste output of nuclear reactors.

Maya

[1] https://en.wikipedia.org/wiki/Integral_Fast_Reactor#Advantages
[2] https://en.wikipedia.org/wiki/Breeder_reactor
[3] https://en.wikipedia.org/wiki/Integral_Fast_Reactor
[4] https://en.wikipedia.org/wiki/Sodium-Cooled_Fast_Reactor
[5] https://en.wikipedia.org/wiki/S-PRISM
[6] https://en.wikipedia.org/wiki/Long-lived_fission_product
[7] https://en.wikipedia.org/wiki/Technetium-99
[8] https://en.wikipedia.org/wiki/Granite#Natural_radiation

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Filed under: Analysis, Nuclear Technology, , , , ,

Protein Synthesis; Design Of Synthesis Unit

In the previous article on protein synthesis [1] we addressed the way biological (eukaryotic) cells synthesize the proteins which make up said cells and other structures in the body in addition to performing various other tasks. The basic summary of this process is transcription of DNA into messenger RNA (mRNA) which is then fitted into ribosomes which use transfer RNA (tRNA) as an intermediate form to translate codons of three nucleotides on the mRNA into one of about twenty possible alpha-amino acids [2]. The resulting string of amino acids then folds due to molecular forces into a 3D form, its final shape determining its function due to the active surfaces on the outside of the protein.

In artificial synthesis of proteins there are a few possible ways to approach this issue, which will be the focus of this article. The most basic approach is essentially the use of an artificial ribosome, whereby the transfer of mRNA through it is simulated and tRNA units with alpha-amino acids are present. The faster, superior, but possibly more complex approach is to directly attach the relevant amino-acid onto the protein string. We’ll examine both option.

The artificial ribosome option (AR approach) is attractive in that it stays close to the existing eukaryote setup, something which we’re all familiar with. We can use existing tRNA, and just keep adding the proper amino-acids to the fluid. The artificial ribosome would need to receive information and adapt the template on its surface based on it to protrude the relevant codons for the anti-codon of the matching tRNA unit to attach to and thus proceed with the formation of the protein string. This means a fairly light-weight setup, within reach of existing nano-technology. The synthesis of an AR unit would be quite involved, but not impossible. The communication protocol would be interesting, and may result in something very much akin to mRNA. In the end this may end up being a fairly complex imitation of the biological system.

On the other hand there’s the ‘2D printer’ setup of the Direct Attachment (DA) approach, which at first does seem more complex, but reduces protein synthesis to the very basics. There’s no more mRNA, ribosome, tRNA and free-floating resources and data in fluid. Instead there’s a single unit which has reservoirs containing the alpha-amino acids which could be drawn into the reservoirs or otherwise refilled, which opens or closes the relevant reservoirs when a particular amino acid is needed. Either the protein string could be moved along the reservoirs, or the reservoirs could be moving in a kind of head, or a pick-and-place approach could be used to transport the amino acid. Or maybe a simple transport system, such as the endoplasmic reticulum uses.

Frankly, given the choice I would go with the DA approach for the simple reason that it allows for many adaptations and much more control. The communication protocol is still an issue, but by dropping the complex addressing of mRNA to tRNA to protein string and using a simple direct addressing in theory this shouldn’t be too much of an issue. As remote control may be desirable the use of something reliable such as the electric signaling of a nerve cell could be used. One wouldn’t be limited to purely biological structures either, and use semi-conductor techniques, akin to those of lab-on-a-chip configurations.

The next article on protein synthesis should further work out the design of the DA approach. Please look forward to it 🙂

Maya

[1] https://jinzouningen.wordpress.com/2012/03/02/protein-synthesis-polymer-design/
[2] http://en.wikipedia.org/wiki/Amino_acid

Filed under: Polymers, Synthesis, , , , , , ,

Author

Maya Posch: professional software engineer and game developer. Graphics artist and all-around science junky.

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